/* * Generic SSL/TLS messaging layer functions * (record layer + retransmission state machine) * * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* * http://www.ietf.org/rfc/rfc2246.txt * http://www.ietf.org/rfc/rfc4346.txt */ #include "common.h" #if defined(MBEDTLS_SSL_TLS_C) #include "mbedtls/platform.h" #include "mbedtls/ssl.h" #include "ssl_misc.h" #include "mbedtls/debug.h" #include "mbedtls/error.h" #include "mbedtls/platform_util.h" #include "mbedtls/version.h" #include "constant_time_internal.h" #include "mbedtls/constant_time.h" #include #if defined(MBEDTLS_USE_PSA_CRYPTO) #include "psa_util_internal.h" #include "psa/crypto.h" #endif #if defined(MBEDTLS_X509_CRT_PARSE_C) #include "mbedtls/oid.h" #endif #if defined(MBEDTLS_USE_PSA_CRYPTO) /* Define a local translating function to save code size by not using too many * arguments in each translating place. */ static int local_err_translation(psa_status_t status) { return psa_status_to_mbedtls(status, psa_to_ssl_errors, ARRAY_LENGTH(psa_to_ssl_errors), psa_generic_status_to_mbedtls); } #define PSA_TO_MBEDTLS_ERR(status) local_err_translation(status) #endif #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) #if defined(MBEDTLS_USE_PSA_CRYPTO) #if defined(PSA_WANT_ALG_SHA_384) #define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_384) #elif defined(PSA_WANT_ALG_SHA_256) #define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_256) #else /* See check_config.h */ #define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_1) #endif MBEDTLS_STATIC_TESTABLE int mbedtls_ct_hmac(mbedtls_svc_key_id_t key, psa_algorithm_t mac_alg, const unsigned char *add_data, size_t add_data_len, const unsigned char *data, size_t data_len_secret, size_t min_data_len, size_t max_data_len, unsigned char *output) { /* * This function breaks the HMAC abstraction and uses psa_hash_clone() * extension in order to get constant-flow behaviour. * * HMAC(msg) is defined as HASH(okey + HASH(ikey + msg)) where + means * concatenation, and okey/ikey are the XOR of the key with some fixed bit * patterns (see RFC 2104, sec. 2). * * We'll first compute ikey/okey, then inner_hash = HASH(ikey + msg) by * hashing up to minlen, then cloning the context, and for each byte up * to maxlen finishing up the hash computation, keeping only the * correct result. * * Then we only need to compute HASH(okey + inner_hash) and we're done. */ psa_algorithm_t hash_alg = PSA_ALG_HMAC_GET_HASH(mac_alg); const size_t block_size = PSA_HASH_BLOCK_LENGTH(hash_alg); unsigned char key_buf[MAX_HASH_BLOCK_LENGTH]; const size_t hash_size = PSA_HASH_LENGTH(hash_alg); psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT; size_t hash_length; unsigned char aux_out[PSA_HASH_MAX_SIZE]; psa_hash_operation_t aux_operation = PSA_HASH_OPERATION_INIT; size_t offset; psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; size_t mac_key_length; size_t i; #define PSA_CHK(func_call) \ do { \ status = (func_call); \ if (status != PSA_SUCCESS) \ goto cleanup; \ } while (0) /* Export MAC key * We assume key length is always exactly the output size * which is never more than the block size, thus we use block_size * as the key buffer size. */ PSA_CHK(psa_export_key(key, key_buf, block_size, &mac_key_length)); /* Calculate ikey */ for (i = 0; i < mac_key_length; i++) { key_buf[i] = (unsigned char) (key_buf[i] ^ 0x36); } for (; i < block_size; ++i) { key_buf[i] = 0x36; } PSA_CHK(psa_hash_setup(&operation, hash_alg)); /* Now compute inner_hash = HASH(ikey + msg) */ PSA_CHK(psa_hash_update(&operation, key_buf, block_size)); PSA_CHK(psa_hash_update(&operation, add_data, add_data_len)); PSA_CHK(psa_hash_update(&operation, data, min_data_len)); /* Fill the hash buffer in advance with something that is * not a valid hash (barring an attack on the hash and * deliberately-crafted input), in case the caller doesn't * check the return status properly. */ memset(output, '!', hash_size); /* For each possible length, compute the hash up to that point */ for (offset = min_data_len; offset <= max_data_len; offset++) { PSA_CHK(psa_hash_clone(&operation, &aux_operation)); PSA_CHK(psa_hash_finish(&aux_operation, aux_out, PSA_HASH_MAX_SIZE, &hash_length)); /* Keep only the correct inner_hash in the output buffer */ mbedtls_ct_memcpy_if(mbedtls_ct_uint_eq(offset, data_len_secret), output, aux_out, NULL, hash_size); if (offset < max_data_len) { PSA_CHK(psa_hash_update(&operation, data + offset, 1)); } } /* Abort current operation to prepare for final operation */ PSA_CHK(psa_hash_abort(&operation)); /* Calculate okey */ for (i = 0; i < mac_key_length; i++) { key_buf[i] = (unsigned char) ((key_buf[i] ^ 0x36) ^ 0x5C); } for (; i < block_size; ++i) { key_buf[i] = 0x5C; } /* Now compute HASH(okey + inner_hash) */ PSA_CHK(psa_hash_setup(&operation, hash_alg)); PSA_CHK(psa_hash_update(&operation, key_buf, block_size)); PSA_CHK(psa_hash_update(&operation, output, hash_size)); PSA_CHK(psa_hash_finish(&operation, output, hash_size, &hash_length)); #undef PSA_CHK cleanup: mbedtls_platform_zeroize(key_buf, MAX_HASH_BLOCK_LENGTH); mbedtls_platform_zeroize(aux_out, PSA_HASH_MAX_SIZE); psa_hash_abort(&operation); psa_hash_abort(&aux_operation); return PSA_TO_MBEDTLS_ERR(status); } #undef MAX_HASH_BLOCK_LENGTH #else MBEDTLS_STATIC_TESTABLE int mbedtls_ct_hmac(mbedtls_md_context_t *ctx, const unsigned char *add_data, size_t add_data_len, const unsigned char *data, size_t data_len_secret, size_t min_data_len, size_t max_data_len, unsigned char *output) { /* * This function breaks the HMAC abstraction and uses the md_clone() * extension to the MD API in order to get constant-flow behaviour. * * HMAC(msg) is defined as HASH(okey + HASH(ikey + msg)) where + means * concatenation, and okey/ikey are the XOR of the key with some fixed bit * patterns (see RFC 2104, sec. 2), which are stored in ctx->hmac_ctx. * * We'll first compute inner_hash = HASH(ikey + msg) by hashing up to * minlen, then cloning the context, and for each byte up to maxlen * finishing up the hash computation, keeping only the correct result. * * Then we only need to compute HASH(okey + inner_hash) and we're done. */ const mbedtls_md_type_t md_alg = mbedtls_md_get_type(ctx->md_info); /* TLS 1.2 only supports SHA-384, SHA-256, SHA-1, MD-5, * all of which have the same block size except SHA-384. */ const size_t block_size = md_alg == MBEDTLS_MD_SHA384 ? 128 : 64; const unsigned char * const ikey = ctx->hmac_ctx; const unsigned char * const okey = ikey + block_size; const size_t hash_size = mbedtls_md_get_size(ctx->md_info); unsigned char aux_out[MBEDTLS_MD_MAX_SIZE]; mbedtls_md_context_t aux; size_t offset; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_md_init(&aux); #define MD_CHK(func_call) \ do { \ ret = (func_call); \ if (ret != 0) \ goto cleanup; \ } while (0) MD_CHK(mbedtls_md_setup(&aux, ctx->md_info, 0)); /* After hmac_start() of hmac_reset(), ikey has already been hashed, * so we can start directly with the message */ MD_CHK(mbedtls_md_update(ctx, add_data, add_data_len)); MD_CHK(mbedtls_md_update(ctx, data, min_data_len)); /* Fill the hash buffer in advance with something that is * not a valid hash (barring an attack on the hash and * deliberately-crafted input), in case the caller doesn't * check the return status properly. */ memset(output, '!', hash_size); /* For each possible length, compute the hash up to that point */ for (offset = min_data_len; offset <= max_data_len; offset++) { MD_CHK(mbedtls_md_clone(&aux, ctx)); MD_CHK(mbedtls_md_finish(&aux, aux_out)); /* Keep only the correct inner_hash in the output buffer */ mbedtls_ct_memcpy_if(mbedtls_ct_uint_eq(offset, data_len_secret), output, aux_out, NULL, hash_size); if (offset < max_data_len) { MD_CHK(mbedtls_md_update(ctx, data + offset, 1)); } } /* The context needs to finish() before it starts() again */ MD_CHK(mbedtls_md_finish(ctx, aux_out)); /* Now compute HASH(okey + inner_hash) */ MD_CHK(mbedtls_md_starts(ctx)); MD_CHK(mbedtls_md_update(ctx, okey, block_size)); MD_CHK(mbedtls_md_update(ctx, output, hash_size)); MD_CHK(mbedtls_md_finish(ctx, output)); /* Done, get ready for next time */ MD_CHK(mbedtls_md_hmac_reset(ctx)); #undef MD_CHK cleanup: mbedtls_md_free(&aux); return ret; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */ static uint32_t ssl_get_hs_total_len(mbedtls_ssl_context const *ssl); /* * Start a timer. * Passing millisecs = 0 cancels a running timer. */ void mbedtls_ssl_set_timer(mbedtls_ssl_context *ssl, uint32_t millisecs) { if (ssl->f_set_timer == NULL) { return; } MBEDTLS_SSL_DEBUG_MSG(3, ("set_timer to %d ms", (int) millisecs)); ssl->f_set_timer(ssl->p_timer, millisecs / 4, millisecs); } /* * Return -1 is timer is expired, 0 if it isn't. */ int mbedtls_ssl_check_timer(mbedtls_ssl_context *ssl) { if (ssl->f_get_timer == NULL) { return 0; } if (ssl->f_get_timer(ssl->p_timer) == 2) { MBEDTLS_SSL_DEBUG_MSG(3, ("timer expired")); return -1; } return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_parse_record_header(mbedtls_ssl_context const *ssl, unsigned char *buf, size_t len, mbedtls_record *rec); int mbedtls_ssl_check_record(mbedtls_ssl_context const *ssl, unsigned char *buf, size_t buflen) { int ret = 0; MBEDTLS_SSL_DEBUG_MSG(1, ("=> mbedtls_ssl_check_record")); MBEDTLS_SSL_DEBUG_BUF(3, "record buffer", buf, buflen); /* We don't support record checking in TLS because * there doesn't seem to be a usecase for it. */ if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_STREAM) { ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; goto exit; } #if defined(MBEDTLS_SSL_PROTO_DTLS) else { mbedtls_record rec; ret = ssl_parse_record_header(ssl, buf, buflen, &rec); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(3, "ssl_parse_record_header", ret); goto exit; } if (ssl->transform_in != NULL) { ret = mbedtls_ssl_decrypt_buf(ssl, ssl->transform_in, &rec); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(3, "mbedtls_ssl_decrypt_buf", ret); goto exit; } } } #endif /* MBEDTLS_SSL_PROTO_DTLS */ exit: /* On success, we have decrypted the buffer in-place, so make * sure we don't leak any plaintext data. */ mbedtls_platform_zeroize(buf, buflen); /* For the purpose of this API, treat messages with unexpected CID * as well as such from future epochs as unexpected. */ if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID || ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) { ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; } MBEDTLS_SSL_DEBUG_MSG(1, ("<= mbedtls_ssl_check_record")); return ret; } #define SSL_DONT_FORCE_FLUSH 0 #define SSL_FORCE_FLUSH 1 #if defined(MBEDTLS_SSL_PROTO_DTLS) /* Forward declarations for functions related to message buffering. */ static void ssl_buffering_free_slot(mbedtls_ssl_context *ssl, uint8_t slot); static void ssl_free_buffered_record(mbedtls_ssl_context *ssl); MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_load_buffered_message(mbedtls_ssl_context *ssl); MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_load_buffered_record(mbedtls_ssl_context *ssl); MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_buffer_message(mbedtls_ssl_context *ssl); MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_buffer_future_record(mbedtls_ssl_context *ssl, mbedtls_record const *rec); MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_next_record_is_in_datagram(mbedtls_ssl_context *ssl); static size_t ssl_get_maximum_datagram_size(mbedtls_ssl_context const *ssl) { size_t mtu = mbedtls_ssl_get_current_mtu(ssl); #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) size_t out_buf_len = ssl->out_buf_len; #else size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN; #endif if (mtu != 0 && mtu < out_buf_len) { return mtu; } return out_buf_len; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_get_remaining_space_in_datagram(mbedtls_ssl_context const *ssl) { size_t const bytes_written = ssl->out_left; size_t const mtu = ssl_get_maximum_datagram_size(ssl); /* Double-check that the write-index hasn't gone * past what we can transmit in a single datagram. */ if (bytes_written > mtu) { /* Should never happen... */ return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } return (int) (mtu - bytes_written); } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_get_remaining_payload_in_datagram(mbedtls_ssl_context const *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t remaining, expansion; size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN; #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) const size_t mfl = mbedtls_ssl_get_output_max_frag_len(ssl); if (max_len > mfl) { max_len = mfl; } /* By the standard (RFC 6066 Sect. 4), the MFL extension * only limits the maximum record payload size, so in theory * we would be allowed to pack multiple records of payload size * MFL into a single datagram. However, this would mean that there's * no way to explicitly communicate MTU restrictions to the peer. * * The following reduction of max_len makes sure that we never * write datagrams larger than MFL + Record Expansion Overhead. */ if (max_len <= ssl->out_left) { return 0; } max_len -= ssl->out_left; #endif ret = ssl_get_remaining_space_in_datagram(ssl); if (ret < 0) { return ret; } remaining = (size_t) ret; ret = mbedtls_ssl_get_record_expansion(ssl); if (ret < 0) { return ret; } expansion = (size_t) ret; if (remaining <= expansion) { return 0; } remaining -= expansion; if (remaining >= max_len) { remaining = max_len; } return (int) remaining; } /* * Double the retransmit timeout value, within the allowed range, * returning -1 if the maximum value has already been reached. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_double_retransmit_timeout(mbedtls_ssl_context *ssl) { uint32_t new_timeout; if (ssl->handshake->retransmit_timeout >= ssl->conf->hs_timeout_max) { return -1; } /* Implement the final paragraph of RFC 6347 section 4.1.1.1 * in the following way: after the initial transmission and a first * retransmission, back off to a temporary estimated MTU of 508 bytes. * This value is guaranteed to be deliverable (if not guaranteed to be * delivered) of any compliant IPv4 (and IPv6) network, and should work * on most non-IP stacks too. */ if (ssl->handshake->retransmit_timeout != ssl->conf->hs_timeout_min) { ssl->handshake->mtu = 508; MBEDTLS_SSL_DEBUG_MSG(2, ("mtu autoreduction to %d bytes", ssl->handshake->mtu)); } new_timeout = 2 * ssl->handshake->retransmit_timeout; /* Avoid arithmetic overflow and range overflow */ if (new_timeout < ssl->handshake->retransmit_timeout || new_timeout > ssl->conf->hs_timeout_max) { new_timeout = ssl->conf->hs_timeout_max; } ssl->handshake->retransmit_timeout = new_timeout; MBEDTLS_SSL_DEBUG_MSG(3, ("update timeout value to %lu millisecs", (unsigned long) ssl->handshake->retransmit_timeout)); return 0; } static void ssl_reset_retransmit_timeout(mbedtls_ssl_context *ssl) { ssl->handshake->retransmit_timeout = ssl->conf->hs_timeout_min; MBEDTLS_SSL_DEBUG_MSG(3, ("update timeout value to %lu millisecs", (unsigned long) ssl->handshake->retransmit_timeout)); } #endif /* MBEDTLS_SSL_PROTO_DTLS */ /* * Encryption/decryption functions */ #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) || defined(MBEDTLS_SSL_PROTO_TLS1_3) static size_t ssl_compute_padding_length(size_t len, size_t granularity) { return (granularity - (len + 1) % granularity) % granularity; } /* This functions transforms a (D)TLS plaintext fragment and a record content * type into an instance of the (D)TLSInnerPlaintext structure. This is used * in DTLS 1.2 + CID and within TLS 1.3 to allow flexible padding and to protect * a record's content type. * * struct { * opaque content[DTLSPlaintext.length]; * ContentType real_type; * uint8 zeros[length_of_padding]; * } (D)TLSInnerPlaintext; * * Input: * - `content`: The beginning of the buffer holding the * plaintext to be wrapped. * - `*content_size`: The length of the plaintext in Bytes. * - `max_len`: The number of Bytes available starting from * `content`. This must be `>= *content_size`. * - `rec_type`: The desired record content type. * * Output: * - `content`: The beginning of the resulting (D)TLSInnerPlaintext structure. * - `*content_size`: The length of the resulting (D)TLSInnerPlaintext structure. * * Returns: * - `0` on success. * - A negative error code if `max_len` didn't offer enough space * for the expansion. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_build_inner_plaintext(unsigned char *content, size_t *content_size, size_t remaining, uint8_t rec_type, size_t pad) { size_t len = *content_size; /* Write real content type */ if (remaining == 0) { return -1; } content[len] = rec_type; len++; remaining--; if (remaining < pad) { return -1; } memset(content + len, 0, pad); len += pad; remaining -= pad; *content_size = len; return 0; } /* This function parses a (D)TLSInnerPlaintext structure. * See ssl_build_inner_plaintext() for details. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_parse_inner_plaintext(unsigned char const *content, size_t *content_size, uint8_t *rec_type) { size_t remaining = *content_size; /* Determine length of padding by skipping zeroes from the back. */ do { if (remaining == 0) { return -1; } remaining--; } while (content[remaining] == 0); *content_size = remaining; *rec_type = content[remaining]; return 0; } #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID || MBEDTLS_SSL_PROTO_TLS1_3 */ /* The size of the `add_data` structure depends on various * factors, namely * * 1) CID functionality disabled * * additional_data = * 8: seq_num + * 1: type + * 2: version + * 2: length of inner plaintext + * * size = 13 bytes * * 2) CID functionality based on RFC 9146 enabled * * size = 8 + 1 + 1 + 1 + 2 + 2 + 6 + 2 + CID-length * = 23 + CID-length * * 3) CID functionality based on legacy CID version according to draft-ietf-tls-dtls-connection-id-05 * https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05 * * size = 13 + 1 + CID-length * * More information about the CID usage: * * Per Section 5.3 of draft-ietf-tls-dtls-connection-id-05 the * size of the additional data structure is calculated as: * * additional_data = * 8: seq_num + * 1: tls12_cid + * 2: DTLSCipherText.version + * n: cid + * 1: cid_length + * 2: length_of_DTLSInnerPlaintext * * Per RFC 9146 the size of the add_data structure is calculated as: * * additional_data = * 8: seq_num_placeholder + * 1: tls12_cid + * 1: cid_length + * 1: tls12_cid + * 2: DTLSCiphertext.version + * 2: epoch + * 6: sequence_number + * n: cid + * 2: length_of_DTLSInnerPlaintext * */ static void ssl_extract_add_data_from_record(unsigned char *add_data, size_t *add_data_len, mbedtls_record *rec, mbedtls_ssl_protocol_version tls_version, size_t taglen) { /* Several types of ciphers have been defined for use with TLS and DTLS, * and the MAC calculations for those ciphers differ slightly. Further * variants were added when the CID functionality was added with RFC 9146. * This implementations also considers the use of a legacy version of the * CID specification published in draft-ietf-tls-dtls-connection-id-05, * which is used in deployments. * * We will distinguish between the non-CID and the CID cases below. * * --- Non-CID cases --- * * Quoting RFC 5246 (TLS 1.2): * * additional_data = seq_num + TLSCompressed.type + * TLSCompressed.version + TLSCompressed.length; * * For TLS 1.3, the record sequence number is dropped from the AAD * and encoded within the nonce of the AEAD operation instead. * Moreover, the additional data involves the length of the TLS * ciphertext, not the TLS plaintext as in earlier versions. * Quoting RFC 8446 (TLS 1.3): * * additional_data = TLSCiphertext.opaque_type || * TLSCiphertext.legacy_record_version || * TLSCiphertext.length * * We pass the tag length to this function in order to compute the * ciphertext length from the inner plaintext length rec->data_len via * * TLSCiphertext.length = TLSInnerPlaintext.length + taglen. * * --- CID cases --- * * RFC 9146 uses a common pattern when constructing the data * passed into a MAC / AEAD cipher. * * Data concatenation for MACs used with block ciphers with * Encrypt-then-MAC Processing (with CID): * * data = seq_num_placeholder + * tls12_cid + * cid_length + * tls12_cid + * DTLSCiphertext.version + * epoch + * sequence_number + * cid + * DTLSCiphertext.length + * IV + * ENC(content + padding + padding_length) * * Data concatenation for MACs used with block ciphers (with CID): * * data = seq_num_placeholder + * tls12_cid + * cid_length + * tls12_cid + * DTLSCiphertext.version + * epoch + * sequence_number + * cid + * length_of_DTLSInnerPlaintext + * DTLSInnerPlaintext.content + * DTLSInnerPlaintext.real_type + * DTLSInnerPlaintext.zeros * * AEAD ciphers use the following additional data calculation (with CIDs): * * additional_data = seq_num_placeholder + * tls12_cid + * cid_length + * tls12_cid + * DTLSCiphertext.version + * epoch + * sequence_number + * cid + * length_of_DTLSInnerPlaintext * * Section 5.3 of draft-ietf-tls-dtls-connection-id-05 (for legacy CID use) * defines the additional data calculation as follows: * * additional_data = seq_num + * tls12_cid + * DTLSCipherText.version + * cid + * cid_length + * length_of_DTLSInnerPlaintext */ unsigned char *cur = add_data; size_t ad_len_field = rec->data_len; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \ MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0 const unsigned char seq_num_placeholder[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; #endif #if defined(MBEDTLS_SSL_PROTO_TLS1_3) if (tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { /* In TLS 1.3, the AAD contains the length of the TLSCiphertext, * which differs from the length of the TLSInnerPlaintext * by the length of the authentication tag. */ ad_len_field += taglen; } else #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ { ((void) tls_version); ((void) taglen); #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \ MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0 if (rec->cid_len != 0) { // seq_num_placeholder memcpy(cur, seq_num_placeholder, sizeof(seq_num_placeholder)); cur += sizeof(seq_num_placeholder); // tls12_cid type *cur = rec->type; cur++; // cid_length *cur = rec->cid_len; cur++; } else #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ { // epoch + sequence number memcpy(cur, rec->ctr, sizeof(rec->ctr)); cur += sizeof(rec->ctr); } } // type *cur = rec->type; cur++; // version memcpy(cur, rec->ver, sizeof(rec->ver)); cur += sizeof(rec->ver); #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \ MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 1 if (rec->cid_len != 0) { // CID memcpy(cur, rec->cid, rec->cid_len); cur += rec->cid_len; // cid_length *cur = rec->cid_len; cur++; // length of inner plaintext MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0); cur += 2; } else #elif defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \ MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0 if (rec->cid_len != 0) { // epoch + sequence number memcpy(cur, rec->ctr, sizeof(rec->ctr)); cur += sizeof(rec->ctr); // CID memcpy(cur, rec->cid, rec->cid_len); cur += rec->cid_len; // length of inner plaintext MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0); cur += 2; } else #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ { MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0); cur += 2; } *add_data_len = cur - add_data; } #if defined(MBEDTLS_SSL_HAVE_AEAD) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_transform_aead_dynamic_iv_is_explicit( mbedtls_ssl_transform const *transform) { return transform->ivlen != transform->fixed_ivlen; } /* Compute IV := ( fixed_iv || 0 ) XOR ( 0 || dynamic_IV ) * * Concretely, this occurs in two variants: * * a) Fixed and dynamic IV lengths add up to total IV length, giving * IV = fixed_iv || dynamic_iv * * This variant is used in TLS 1.2 when used with GCM or CCM. * * b) Fixed IV lengths matches total IV length, giving * IV = fixed_iv XOR ( 0 || dynamic_iv ) * * This variant occurs in TLS 1.3 and for TLS 1.2 when using ChaChaPoly. * * See also the documentation of mbedtls_ssl_transform. * * This function has the precondition that * * dst_iv_len >= max( fixed_iv_len, dynamic_iv_len ) * * which has to be ensured by the caller. If this precondition * violated, the behavior of this function is undefined. */ static void ssl_build_record_nonce(unsigned char *dst_iv, size_t dst_iv_len, unsigned char const *fixed_iv, size_t fixed_iv_len, unsigned char const *dynamic_iv, size_t dynamic_iv_len) { /* Start with Fixed IV || 0 */ memset(dst_iv, 0, dst_iv_len); memcpy(dst_iv, fixed_iv, fixed_iv_len); dst_iv += dst_iv_len - dynamic_iv_len; mbedtls_xor(dst_iv, dst_iv, dynamic_iv, dynamic_iv_len); } #endif /* MBEDTLS_SSL_HAVE_AEAD */ int mbedtls_ssl_encrypt_buf(mbedtls_ssl_context *ssl, mbedtls_ssl_transform *transform, mbedtls_record *rec, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng) { mbedtls_ssl_mode_t ssl_mode; int auth_done = 0; unsigned char *data; /* For an explanation of the additional data length see * the description of ssl_extract_add_data_from_record(). */ #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) unsigned char add_data[23 + MBEDTLS_SSL_CID_OUT_LEN_MAX]; #else unsigned char add_data[13]; #endif size_t add_data_len; size_t post_avail; /* The SSL context is only used for debugging purposes! */ #if !defined(MBEDTLS_DEBUG_C) ssl = NULL; /* make sure we don't use it except for debug */ ((void) ssl); #endif /* The PRNG is used for dynamic IV generation that's used * for CBC transformations in TLS 1.2. */ #if !(defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \ defined(MBEDTLS_SSL_PROTO_TLS1_2)) ((void) f_rng); ((void) p_rng); #endif MBEDTLS_SSL_DEBUG_MSG(2, ("=> encrypt buf")); if (transform == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("no transform provided to encrypt_buf")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } if (rec == NULL || rec->buf == NULL || rec->buf_len < rec->data_offset || rec->buf_len - rec->data_offset < rec->data_len #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) || rec->cid_len != 0 #endif ) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad record structure provided to encrypt_buf")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } ssl_mode = mbedtls_ssl_get_mode_from_transform(transform); data = rec->buf + rec->data_offset; post_avail = rec->buf_len - (rec->data_len + rec->data_offset); MBEDTLS_SSL_DEBUG_BUF(4, "before encrypt: output payload", data, rec->data_len); if (rec->data_len > MBEDTLS_SSL_OUT_CONTENT_LEN) { MBEDTLS_SSL_DEBUG_MSG(1, ("Record content %" MBEDTLS_PRINTF_SIZET " too large, maximum %" MBEDTLS_PRINTF_SIZET, rec->data_len, (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN)); return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } /* The following two code paths implement the (D)TLSInnerPlaintext * structure present in TLS 1.3 and DTLS 1.2 + CID. * * See ssl_build_inner_plaintext() for more information. * * Note that this changes `rec->data_len`, and hence * `post_avail` needs to be recalculated afterwards. * * Note also that the two code paths cannot occur simultaneously * since they apply to different versions of the protocol. There * is hence no risk of double-addition of the inner plaintext. */ #if defined(MBEDTLS_SSL_PROTO_TLS1_3) if (transform->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { size_t padding = ssl_compute_padding_length(rec->data_len, MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY); if (ssl_build_inner_plaintext(data, &rec->data_len, post_avail, rec->type, padding) != 0) { return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } rec->type = MBEDTLS_SSL_MSG_APPLICATION_DATA; } #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) /* * Add CID information */ rec->cid_len = transform->out_cid_len; memcpy(rec->cid, transform->out_cid, transform->out_cid_len); MBEDTLS_SSL_DEBUG_BUF(3, "CID", rec->cid, rec->cid_len); if (rec->cid_len != 0) { size_t padding = ssl_compute_padding_length(rec->data_len, MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY); /* * Wrap plaintext into DTLSInnerPlaintext structure. * See ssl_build_inner_plaintext() for more information. * * Note that this changes `rec->data_len`, and hence * `post_avail` needs to be recalculated afterwards. */ if (ssl_build_inner_plaintext(data, &rec->data_len, post_avail, rec->type, padding) != 0) { return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } rec->type = MBEDTLS_SSL_MSG_CID; } #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ post_avail = rec->buf_len - (rec->data_len + rec->data_offset); /* * Add MAC before if needed */ #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) if (ssl_mode == MBEDTLS_SSL_MODE_STREAM || ssl_mode == MBEDTLS_SSL_MODE_CBC) { if (post_avail < transform->maclen) { MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } #if defined(MBEDTLS_SSL_PROTO_TLS1_2) unsigned char mac[MBEDTLS_SSL_MAC_ADD]; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT; psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; size_t sign_mac_length = 0; #endif /* MBEDTLS_USE_PSA_CRYPTO */ ssl_extract_add_data_from_record(add_data, &add_data_len, rec, transform->tls_version, transform->taglen); #if defined(MBEDTLS_USE_PSA_CRYPTO) status = psa_mac_sign_setup(&operation, transform->psa_mac_enc, transform->psa_mac_alg); if (status != PSA_SUCCESS) { goto hmac_failed_etm_disabled; } status = psa_mac_update(&operation, add_data, add_data_len); if (status != PSA_SUCCESS) { goto hmac_failed_etm_disabled; } status = psa_mac_update(&operation, data, rec->data_len); if (status != PSA_SUCCESS) { goto hmac_failed_etm_disabled; } status = psa_mac_sign_finish(&operation, mac, MBEDTLS_SSL_MAC_ADD, &sign_mac_length); if (status != PSA_SUCCESS) { goto hmac_failed_etm_disabled; } #else ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, add_data, add_data_len); if (ret != 0) { goto hmac_failed_etm_disabled; } ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, data, rec->data_len); if (ret != 0) { goto hmac_failed_etm_disabled; } ret = mbedtls_md_hmac_finish(&transform->md_ctx_enc, mac); if (ret != 0) { goto hmac_failed_etm_disabled; } ret = mbedtls_md_hmac_reset(&transform->md_ctx_enc); if (ret != 0) { goto hmac_failed_etm_disabled; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ memcpy(data + rec->data_len, mac, transform->maclen); #endif MBEDTLS_SSL_DEBUG_BUF(4, "computed mac", data + rec->data_len, transform->maclen); rec->data_len += transform->maclen; post_avail -= transform->maclen; auth_done++; hmac_failed_etm_disabled: mbedtls_platform_zeroize(mac, transform->maclen); #if defined(MBEDTLS_USE_PSA_CRYPTO) ret = PSA_TO_MBEDTLS_ERR(status); status = psa_mac_abort(&operation); if (ret == 0 && status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); } #endif /* MBEDTLS_USE_PSA_CRYPTO */ if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_md_hmac_xxx", ret); return ret; } } #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */ /* * Encrypt */ #if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM) if (ssl_mode == MBEDTLS_SSL_MODE_STREAM) { MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", " "including %d bytes of padding", rec->data_len, 0)); /* The only supported stream cipher is "NULL", * so there's nothing to do here.*/ } else #endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */ #if defined(MBEDTLS_SSL_HAVE_AEAD) if (ssl_mode == MBEDTLS_SSL_MODE_AEAD) { unsigned char iv[12]; unsigned char *dynamic_iv; size_t dynamic_iv_len; int dynamic_iv_is_explicit = ssl_transform_aead_dynamic_iv_is_explicit(transform); #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; #endif /* MBEDTLS_USE_PSA_CRYPTO */ int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; /* Check that there's space for the authentication tag. */ if (post_avail < transform->taglen) { MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } /* * Build nonce for AEAD encryption. * * Note: In the case of CCM and GCM in TLS 1.2, the dynamic * part of the IV is prepended to the ciphertext and * can be chosen freely - in particular, it need not * agree with the record sequence number. * However, since ChaChaPoly as well as all AEAD modes * in TLS 1.3 use the record sequence number as the * dynamic part of the nonce, we uniformly use the * record sequence number here in all cases. */ dynamic_iv = rec->ctr; dynamic_iv_len = sizeof(rec->ctr); ssl_build_record_nonce(iv, sizeof(iv), transform->iv_enc, transform->fixed_ivlen, dynamic_iv, dynamic_iv_len); /* * Build additional data for AEAD encryption. * This depends on the TLS version. */ ssl_extract_add_data_from_record(add_data, &add_data_len, rec, transform->tls_version, transform->taglen); MBEDTLS_SSL_DEBUG_BUF(4, "IV used (internal)", iv, transform->ivlen); MBEDTLS_SSL_DEBUG_BUF(4, "IV used (transmitted)", dynamic_iv, dynamic_iv_is_explicit ? dynamic_iv_len : 0); MBEDTLS_SSL_DEBUG_BUF(4, "additional data used for AEAD", add_data, add_data_len); MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", " "including 0 bytes of padding", rec->data_len)); /* * Encrypt and authenticate */ #if defined(MBEDTLS_USE_PSA_CRYPTO) status = psa_aead_encrypt(transform->psa_key_enc, transform->psa_alg, iv, transform->ivlen, add_data, add_data_len, data, rec->data_len, data, rec->buf_len - (data - rec->buf), &rec->data_len); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_encrypt_buf", ret); return ret; } #else if ((ret = mbedtls_cipher_auth_encrypt_ext(&transform->cipher_ctx_enc, iv, transform->ivlen, add_data, add_data_len, data, rec->data_len, /* src */ data, rec->buf_len - (data - rec->buf), /* dst */ &rec->data_len, transform->taglen)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_auth_encrypt_ext", ret); return ret; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ MBEDTLS_SSL_DEBUG_BUF(4, "after encrypt: tag", data + rec->data_len - transform->taglen, transform->taglen); /* Account for authentication tag. */ post_avail -= transform->taglen; /* * Prefix record content with dynamic IV in case it is explicit. */ if (dynamic_iv_is_explicit != 0) { if (rec->data_offset < dynamic_iv_len) { MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } memcpy(data - dynamic_iv_len, dynamic_iv, dynamic_iv_len); rec->data_offset -= dynamic_iv_len; rec->data_len += dynamic_iv_len; } auth_done++; } else #endif /* MBEDTLS_SSL_HAVE_AEAD */ #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) if (ssl_mode == MBEDTLS_SSL_MODE_CBC || ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t padlen, i; size_t olen; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; size_t part_len; psa_cipher_operation_t cipher_op = PSA_CIPHER_OPERATION_INIT; #endif /* MBEDTLS_USE_PSA_CRYPTO */ /* Currently we're always using minimal padding * (up to 255 bytes would be allowed). */ padlen = transform->ivlen - (rec->data_len + 1) % transform->ivlen; if (padlen == transform->ivlen) { padlen = 0; } /* Check there's enough space in the buffer for the padding. */ if (post_avail < padlen + 1) { MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } for (i = 0; i <= padlen; i++) { data[rec->data_len + i] = (unsigned char) padlen; } rec->data_len += padlen + 1; post_avail -= padlen + 1; #if defined(MBEDTLS_SSL_PROTO_TLS1_2) /* * Prepend per-record IV for block cipher in TLS v1.2 as per * Method 1 (6.2.3.2. in RFC4346 and RFC5246) */ if (f_rng == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("No PRNG provided to encrypt_record routine")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } if (rec->data_offset < transform->ivlen) { MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } /* * Generate IV */ ret = f_rng(p_rng, transform->iv_enc, transform->ivlen); if (ret != 0) { return ret; } memcpy(data - transform->ivlen, transform->iv_enc, transform->ivlen); #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ MBEDTLS_SSL_DEBUG_MSG(3, ("before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", " "including %" MBEDTLS_PRINTF_SIZET " bytes of IV and %" MBEDTLS_PRINTF_SIZET " bytes of padding", rec->data_len, transform->ivlen, padlen + 1)); #if defined(MBEDTLS_USE_PSA_CRYPTO) status = psa_cipher_encrypt_setup(&cipher_op, transform->psa_key_enc, transform->psa_alg); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_encrypt_setup", ret); return ret; } status = psa_cipher_set_iv(&cipher_op, transform->iv_enc, transform->ivlen); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_set_iv", ret); return ret; } status = psa_cipher_update(&cipher_op, data, rec->data_len, data, rec->data_len, &olen); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_update", ret); return ret; } status = psa_cipher_finish(&cipher_op, data + olen, rec->data_len - olen, &part_len); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_finish", ret); return ret; } olen += part_len; #else if ((ret = mbedtls_cipher_crypt(&transform->cipher_ctx_enc, transform->iv_enc, transform->ivlen, data, rec->data_len, data, &olen)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_crypt", ret); return ret; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ if (rec->data_len != olen) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } data -= transform->ivlen; rec->data_offset -= transform->ivlen; rec->data_len += transform->ivlen; #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC) if (auth_done == 0) { unsigned char mac[MBEDTLS_SSL_MAC_ADD]; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT; size_t sign_mac_length = 0; #endif /* MBEDTLS_USE_PSA_CRYPTO */ /* MAC(MAC_write_key, add_data, IV, ENC(content + padding + padding_length)) */ if (post_avail < transform->maclen) { MBEDTLS_SSL_DEBUG_MSG(1, ("Buffer provided for encrypted record not large enough")); return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } ssl_extract_add_data_from_record(add_data, &add_data_len, rec, transform->tls_version, transform->taglen); MBEDTLS_SSL_DEBUG_MSG(3, ("using encrypt then mac")); MBEDTLS_SSL_DEBUG_BUF(4, "MAC'd meta-data", add_data, add_data_len); #if defined(MBEDTLS_USE_PSA_CRYPTO) status = psa_mac_sign_setup(&operation, transform->psa_mac_enc, transform->psa_mac_alg); if (status != PSA_SUCCESS) { goto hmac_failed_etm_enabled; } status = psa_mac_update(&operation, add_data, add_data_len); if (status != PSA_SUCCESS) { goto hmac_failed_etm_enabled; } status = psa_mac_update(&operation, data, rec->data_len); if (status != PSA_SUCCESS) { goto hmac_failed_etm_enabled; } status = psa_mac_sign_finish(&operation, mac, MBEDTLS_SSL_MAC_ADD, &sign_mac_length); if (status != PSA_SUCCESS) { goto hmac_failed_etm_enabled; } #else ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, add_data, add_data_len); if (ret != 0) { goto hmac_failed_etm_enabled; } ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, data, rec->data_len); if (ret != 0) { goto hmac_failed_etm_enabled; } ret = mbedtls_md_hmac_finish(&transform->md_ctx_enc, mac); if (ret != 0) { goto hmac_failed_etm_enabled; } ret = mbedtls_md_hmac_reset(&transform->md_ctx_enc); if (ret != 0) { goto hmac_failed_etm_enabled; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ memcpy(data + rec->data_len, mac, transform->maclen); rec->data_len += transform->maclen; post_avail -= transform->maclen; auth_done++; hmac_failed_etm_enabled: mbedtls_platform_zeroize(mac, transform->maclen); #if defined(MBEDTLS_USE_PSA_CRYPTO) ret = PSA_TO_MBEDTLS_ERR(status); status = psa_mac_abort(&operation); if (ret == 0 && status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); } #endif /* MBEDTLS_USE_PSA_CRYPTO */ if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "HMAC calculation failed", ret); return ret; } } #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */ } else #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC) */ { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* Make extra sure authentication was performed, exactly once */ if (auth_done != 1) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } MBEDTLS_SSL_DEBUG_MSG(2, ("<= encrypt buf")); return 0; } int mbedtls_ssl_decrypt_buf(mbedtls_ssl_context const *ssl, mbedtls_ssl_transform *transform, mbedtls_record *rec) { #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) || defined(MBEDTLS_SSL_HAVE_AEAD) size_t olen; #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC || MBEDTLS_SSL_HAVE_AEAD */ mbedtls_ssl_mode_t ssl_mode; int ret; int auth_done = 0; #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) size_t padlen = 0; mbedtls_ct_condition_t correct = MBEDTLS_CT_TRUE; #endif unsigned char *data; /* For an explanation of the additional data length see * the description of ssl_extract_add_data_from_record(). */ #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) unsigned char add_data[23 + MBEDTLS_SSL_CID_IN_LEN_MAX]; #else unsigned char add_data[13]; #endif size_t add_data_len; #if !defined(MBEDTLS_DEBUG_C) ssl = NULL; /* make sure we don't use it except for debug */ ((void) ssl); #endif MBEDTLS_SSL_DEBUG_MSG(2, ("=> decrypt buf")); if (rec == NULL || rec->buf == NULL || rec->buf_len < rec->data_offset || rec->buf_len - rec->data_offset < rec->data_len) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad record structure provided to decrypt_buf")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } data = rec->buf + rec->data_offset; ssl_mode = mbedtls_ssl_get_mode_from_transform(transform); #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) /* * Match record's CID with incoming CID. */ if (rec->cid_len != transform->in_cid_len || memcmp(rec->cid, transform->in_cid, rec->cid_len) != 0) { return MBEDTLS_ERR_SSL_UNEXPECTED_CID; } #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ #if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM) if (ssl_mode == MBEDTLS_SSL_MODE_STREAM) { if (rec->data_len < transform->maclen) { MBEDTLS_SSL_DEBUG_MSG(1, ("Record too short for MAC:" " %" MBEDTLS_PRINTF_SIZET " < %" MBEDTLS_PRINTF_SIZET, rec->data_len, transform->maclen)); return MBEDTLS_ERR_SSL_INVALID_MAC; } /* The only supported stream cipher is "NULL", * so there's no encryption to do here.*/ } else #endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */ #if defined(MBEDTLS_SSL_HAVE_AEAD) if (ssl_mode == MBEDTLS_SSL_MODE_AEAD) { unsigned char iv[12]; unsigned char *dynamic_iv; size_t dynamic_iv_len; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; #endif /* MBEDTLS_USE_PSA_CRYPTO */ /* * Extract dynamic part of nonce for AEAD decryption. * * Note: In the case of CCM and GCM in TLS 1.2, the dynamic * part of the IV is prepended to the ciphertext and * can be chosen freely - in particular, it need not * agree with the record sequence number. */ dynamic_iv_len = sizeof(rec->ctr); if (ssl_transform_aead_dynamic_iv_is_explicit(transform) == 1) { if (rec->data_len < dynamic_iv_len) { MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET " ) < explicit_iv_len (%" MBEDTLS_PRINTF_SIZET ") ", rec->data_len, dynamic_iv_len)); return MBEDTLS_ERR_SSL_INVALID_MAC; } dynamic_iv = data; data += dynamic_iv_len; rec->data_offset += dynamic_iv_len; rec->data_len -= dynamic_iv_len; } else { dynamic_iv = rec->ctr; } /* Check that there's space for the authentication tag. */ if (rec->data_len < transform->taglen) { MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET ") < taglen (%" MBEDTLS_PRINTF_SIZET ") ", rec->data_len, transform->taglen)); return MBEDTLS_ERR_SSL_INVALID_MAC; } rec->data_len -= transform->taglen; /* * Prepare nonce from dynamic and static parts. */ ssl_build_record_nonce(iv, sizeof(iv), transform->iv_dec, transform->fixed_ivlen, dynamic_iv, dynamic_iv_len); /* * Build additional data for AEAD encryption. * This depends on the TLS version. */ ssl_extract_add_data_from_record(add_data, &add_data_len, rec, transform->tls_version, transform->taglen); MBEDTLS_SSL_DEBUG_BUF(4, "additional data used for AEAD", add_data, add_data_len); /* Because of the check above, we know that there are * explicit_iv_len Bytes preceding data, and taglen * bytes following data + data_len. This justifies * the debug message and the invocation of * mbedtls_cipher_auth_decrypt_ext() below. */ MBEDTLS_SSL_DEBUG_BUF(4, "IV used", iv, transform->ivlen); MBEDTLS_SSL_DEBUG_BUF(4, "TAG used", data + rec->data_len, transform->taglen); /* * Decrypt and authenticate */ #if defined(MBEDTLS_USE_PSA_CRYPTO) status = psa_aead_decrypt(transform->psa_key_dec, transform->psa_alg, iv, transform->ivlen, add_data, add_data_len, data, rec->data_len + transform->taglen, data, rec->buf_len - (data - rec->buf), &olen); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_aead_decrypt", ret); return ret; } #else if ((ret = mbedtls_cipher_auth_decrypt_ext(&transform->cipher_ctx_dec, iv, transform->ivlen, add_data, add_data_len, data, rec->data_len + transform->taglen, /* src */ data, rec->buf_len - (data - rec->buf), &olen, /* dst */ transform->taglen)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_auth_decrypt_ext", ret); if (ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED) { return MBEDTLS_ERR_SSL_INVALID_MAC; } return ret; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ auth_done++; /* Double-check that AEAD decryption doesn't change content length. */ if (olen != rec->data_len) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } } else #endif /* MBEDTLS_SSL_HAVE_AEAD */ #if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) if (ssl_mode == MBEDTLS_SSL_MODE_CBC || ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) { size_t minlen = 0; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; size_t part_len; psa_cipher_operation_t cipher_op = PSA_CIPHER_OPERATION_INIT; #endif /* MBEDTLS_USE_PSA_CRYPTO */ /* * Check immediate ciphertext sanity */ #if defined(MBEDTLS_SSL_PROTO_TLS1_2) /* The ciphertext is prefixed with the CBC IV. */ minlen += transform->ivlen; #endif /* Size considerations: * * - The CBC cipher text must not be empty and hence * at least of size transform->ivlen. * * Together with the potential IV-prefix, this explains * the first of the two checks below. * * - The record must contain a MAC, either in plain or * encrypted, depending on whether Encrypt-then-MAC * is used or not. * - If it is, the message contains the IV-prefix, * the CBC ciphertext, and the MAC. * - If it is not, the padded plaintext, and hence * the CBC ciphertext, has at least length maclen + 1 * because there is at least the padding length byte. * * As the CBC ciphertext is not empty, both cases give the * lower bound minlen + maclen + 1 on the record size, which * we test for in the second check below. */ if (rec->data_len < minlen + transform->ivlen || rec->data_len < minlen + transform->maclen + 1) { MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET ") < max( ivlen(%" MBEDTLS_PRINTF_SIZET "), maclen (%" MBEDTLS_PRINTF_SIZET ") " "+ 1 ) ( + expl IV )", rec->data_len, transform->ivlen, transform->maclen)); return MBEDTLS_ERR_SSL_INVALID_MAC; } /* * Authenticate before decrypt if enabled */ #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC) if (ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) { #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT; #else unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD]; #endif /* MBEDTLS_USE_PSA_CRYPTO */ MBEDTLS_SSL_DEBUG_MSG(3, ("using encrypt then mac")); /* Update data_len in tandem with add_data. * * The subtraction is safe because of the previous check * data_len >= minlen + maclen + 1. * * Afterwards, we know that data + data_len is followed by at * least maclen Bytes, which justifies the call to * mbedtls_ct_memcmp() below. * * Further, we still know that data_len > minlen */ rec->data_len -= transform->maclen; ssl_extract_add_data_from_record(add_data, &add_data_len, rec, transform->tls_version, transform->taglen); /* Calculate expected MAC. */ MBEDTLS_SSL_DEBUG_BUF(4, "MAC'd meta-data", add_data, add_data_len); #if defined(MBEDTLS_USE_PSA_CRYPTO) status = psa_mac_verify_setup(&operation, transform->psa_mac_dec, transform->psa_mac_alg); if (status != PSA_SUCCESS) { goto hmac_failed_etm_enabled; } status = psa_mac_update(&operation, add_data, add_data_len); if (status != PSA_SUCCESS) { goto hmac_failed_etm_enabled; } status = psa_mac_update(&operation, data, rec->data_len); if (status != PSA_SUCCESS) { goto hmac_failed_etm_enabled; } /* Compare expected MAC with MAC at the end of the record. */ status = psa_mac_verify_finish(&operation, data + rec->data_len, transform->maclen); if (status != PSA_SUCCESS) { goto hmac_failed_etm_enabled; } #else ret = mbedtls_md_hmac_update(&transform->md_ctx_dec, add_data, add_data_len); if (ret != 0) { goto hmac_failed_etm_enabled; } ret = mbedtls_md_hmac_update(&transform->md_ctx_dec, data, rec->data_len); if (ret != 0) { goto hmac_failed_etm_enabled; } ret = mbedtls_md_hmac_finish(&transform->md_ctx_dec, mac_expect); if (ret != 0) { goto hmac_failed_etm_enabled; } ret = mbedtls_md_hmac_reset(&transform->md_ctx_dec); if (ret != 0) { goto hmac_failed_etm_enabled; } MBEDTLS_SSL_DEBUG_BUF(4, "message mac", data + rec->data_len, transform->maclen); MBEDTLS_SSL_DEBUG_BUF(4, "expected mac", mac_expect, transform->maclen); /* Compare expected MAC with MAC at the end of the record. */ if (mbedtls_ct_memcmp(data + rec->data_len, mac_expect, transform->maclen) != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("message mac does not match")); ret = MBEDTLS_ERR_SSL_INVALID_MAC; goto hmac_failed_etm_enabled; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ auth_done++; hmac_failed_etm_enabled: #if defined(MBEDTLS_USE_PSA_CRYPTO) ret = PSA_TO_MBEDTLS_ERR(status); status = psa_mac_abort(&operation); if (ret == 0 && status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); } #else mbedtls_platform_zeroize(mac_expect, transform->maclen); #endif /* MBEDTLS_USE_PSA_CRYPTO */ if (ret != 0) { if (ret != MBEDTLS_ERR_SSL_INVALID_MAC) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_hmac_xxx", ret); } return ret; } } #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */ /* * Check length sanity */ /* We know from above that data_len > minlen >= 0, * so the following check in particular implies that * data_len >= minlen + ivlen ( = minlen or 2 * minlen ). */ if (rec->data_len % transform->ivlen != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET ") %% ivlen (%" MBEDTLS_PRINTF_SIZET ") != 0", rec->data_len, transform->ivlen)); return MBEDTLS_ERR_SSL_INVALID_MAC; } #if defined(MBEDTLS_SSL_PROTO_TLS1_2) /* * Initialize for prepended IV for block cipher in TLS v1.2 */ /* Safe because data_len >= minlen + ivlen = 2 * ivlen. */ memcpy(transform->iv_dec, data, transform->ivlen); data += transform->ivlen; rec->data_offset += transform->ivlen; rec->data_len -= transform->ivlen; #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ /* We still have data_len % ivlen == 0 and data_len >= ivlen here. */ #if defined(MBEDTLS_USE_PSA_CRYPTO) status = psa_cipher_decrypt_setup(&cipher_op, transform->psa_key_dec, transform->psa_alg); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_decrypt_setup", ret); return ret; } status = psa_cipher_set_iv(&cipher_op, transform->iv_dec, transform->ivlen); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_set_iv", ret); return ret; } status = psa_cipher_update(&cipher_op, data, rec->data_len, data, rec->data_len, &olen); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_update", ret); return ret; } status = psa_cipher_finish(&cipher_op, data + olen, rec->data_len - olen, &part_len); if (status != PSA_SUCCESS) { ret = PSA_TO_MBEDTLS_ERR(status); MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_finish", ret); return ret; } olen += part_len; #else if ((ret = mbedtls_cipher_crypt(&transform->cipher_ctx_dec, transform->iv_dec, transform->ivlen, data, rec->data_len, data, &olen)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_crypt", ret); return ret; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ /* Double-check that length hasn't changed during decryption. */ if (rec->data_len != olen) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* Safe since data_len >= minlen + maclen + 1, so after having * subtracted at most minlen and maclen up to this point, * data_len > 0 (because of data_len % ivlen == 0, it's actually * >= ivlen ). */ padlen = data[rec->data_len - 1]; if (auth_done == 1) { const mbedtls_ct_condition_t ge = mbedtls_ct_uint_ge( rec->data_len, padlen + 1); correct = mbedtls_ct_bool_and(ge, correct); padlen = mbedtls_ct_size_if_else_0(ge, padlen); } else { #if defined(MBEDTLS_SSL_DEBUG_ALL) if (rec->data_len < transform->maclen + padlen + 1) { MBEDTLS_SSL_DEBUG_MSG(1, ("msglen (%" MBEDTLS_PRINTF_SIZET ") < maclen (%" MBEDTLS_PRINTF_SIZET ") + padlen (%" MBEDTLS_PRINTF_SIZET ")", rec->data_len, transform->maclen, padlen + 1)); } #endif const mbedtls_ct_condition_t ge = mbedtls_ct_uint_ge( rec->data_len, transform->maclen + padlen + 1); correct = mbedtls_ct_bool_and(ge, correct); padlen = mbedtls_ct_size_if_else_0(ge, padlen); } padlen++; /* Regardless of the validity of the padding, * we have data_len >= padlen here. */ #if defined(MBEDTLS_SSL_PROTO_TLS1_2) /* The padding check involves a series of up to 256 * consecutive memory reads at the end of the record * plaintext buffer. In order to hide the length and * validity of the padding, always perform exactly * `min(256,plaintext_len)` reads (but take into account * only the last `padlen` bytes for the padding check). */ size_t pad_count = 0; volatile unsigned char * const check = data; /* Index of first padding byte; it has been ensured above * that the subtraction is safe. */ size_t const padding_idx = rec->data_len - padlen; size_t const num_checks = rec->data_len <= 256 ? rec->data_len : 256; size_t const start_idx = rec->data_len - num_checks; size_t idx; for (idx = start_idx; idx < rec->data_len; idx++) { /* pad_count += (idx >= padding_idx) && * (check[idx] == padlen - 1); */ const mbedtls_ct_condition_t a = mbedtls_ct_uint_ge(idx, padding_idx); size_t increment = mbedtls_ct_size_if_else_0(a, 1); const mbedtls_ct_condition_t b = mbedtls_ct_uint_eq(check[idx], padlen - 1); increment = mbedtls_ct_size_if_else_0(b, increment); pad_count += increment; } correct = mbedtls_ct_bool_and(mbedtls_ct_uint_eq(pad_count, padlen), correct); #if defined(MBEDTLS_SSL_DEBUG_ALL) if (padlen > 0 && correct == MBEDTLS_CT_FALSE) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad padding byte detected")); } #endif padlen = mbedtls_ct_size_if_else_0(correct, padlen); #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ /* If the padding was found to be invalid, padlen == 0 * and the subtraction is safe. If the padding was found valid, * padlen hasn't been changed and the previous assertion * data_len >= padlen still holds. */ rec->data_len -= padlen; } else #endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC */ { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } #if defined(MBEDTLS_SSL_DEBUG_ALL) MBEDTLS_SSL_DEBUG_BUF(4, "raw buffer after decryption", data, rec->data_len); #endif /* * Authenticate if not done yet. * Compute the MAC regardless of the padding result (RFC4346, CBCTIME). */ #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) if (auth_done == 0) { unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD] = { 0 }; unsigned char mac_peer[MBEDTLS_SSL_MAC_ADD] = { 0 }; /* For CBC+MAC, If the initial value of padlen was such that * data_len < maclen + padlen + 1, then padlen * got reset to 1, and the initial check * data_len >= minlen + maclen + 1 * guarantees that at this point we still * have at least data_len >= maclen. * * If the initial value of padlen was such that * data_len >= maclen + padlen + 1, then we have * subtracted either padlen + 1 (if the padding was correct) * or 0 (if the padding was incorrect) since then, * hence data_len >= maclen in any case. * * For stream ciphers, we checked above that * data_len >= maclen. */ rec->data_len -= transform->maclen; ssl_extract_add_data_from_record(add_data, &add_data_len, rec, transform->tls_version, transform->taglen); #if defined(MBEDTLS_SSL_PROTO_TLS1_2) /* * The next two sizes are the minimum and maximum values of * data_len over all padlen values. * * They're independent of padlen, since we previously did * data_len -= padlen. * * Note that max_len + maclen is never more than the buffer * length, as we previously did in_msglen -= maclen too. */ const size_t max_len = rec->data_len + padlen; const size_t min_len = (max_len > 256) ? max_len - 256 : 0; #if defined(MBEDTLS_USE_PSA_CRYPTO) ret = mbedtls_ct_hmac(transform->psa_mac_dec, transform->psa_mac_alg, add_data, add_data_len, data, rec->data_len, min_len, max_len, mac_expect); #else ret = mbedtls_ct_hmac(&transform->md_ctx_dec, add_data, add_data_len, data, rec->data_len, min_len, max_len, mac_expect); #endif /* MBEDTLS_USE_PSA_CRYPTO */ if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ct_hmac", ret); goto hmac_failed_etm_disabled; } mbedtls_ct_memcpy_offset(mac_peer, data, rec->data_len, min_len, max_len, transform->maclen); #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ #if defined(MBEDTLS_SSL_DEBUG_ALL) MBEDTLS_SSL_DEBUG_BUF(4, "expected mac", mac_expect, transform->maclen); MBEDTLS_SSL_DEBUG_BUF(4, "message mac", mac_peer, transform->maclen); #endif if (mbedtls_ct_memcmp(mac_peer, mac_expect, transform->maclen) != 0) { #if defined(MBEDTLS_SSL_DEBUG_ALL) MBEDTLS_SSL_DEBUG_MSG(1, ("message mac does not match")); #endif correct = MBEDTLS_CT_FALSE; } auth_done++; hmac_failed_etm_disabled: mbedtls_platform_zeroize(mac_peer, transform->maclen); mbedtls_platform_zeroize(mac_expect, transform->maclen); if (ret != 0) { return ret; } } /* * Finally check the correct flag */ if (correct == MBEDTLS_CT_FALSE) { return MBEDTLS_ERR_SSL_INVALID_MAC; } #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */ /* Make extra sure authentication was performed, exactly once */ if (auth_done != 1) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } #if defined(MBEDTLS_SSL_PROTO_TLS1_3) if (transform->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { /* Remove inner padding and infer true content type. */ ret = ssl_parse_inner_plaintext(data, &rec->data_len, &rec->type); if (ret != 0) { return MBEDTLS_ERR_SSL_INVALID_RECORD; } } #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) if (rec->cid_len != 0) { ret = ssl_parse_inner_plaintext(data, &rec->data_len, &rec->type); if (ret != 0) { return MBEDTLS_ERR_SSL_INVALID_RECORD; } } #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ MBEDTLS_SSL_DEBUG_MSG(2, ("<= decrypt buf")); return 0; } #undef MAC_NONE #undef MAC_PLAINTEXT #undef MAC_CIPHERTEXT /* * Fill the input message buffer by appending data to it. * The amount of data already fetched is in ssl->in_left. * * If we return 0, is it guaranteed that (at least) nb_want bytes are * available (from this read and/or a previous one). Otherwise, an error code * is returned (possibly EOF or WANT_READ). * * With stream transport (TLS) on success ssl->in_left == nb_want, but * with datagram transport (DTLS) on success ssl->in_left >= nb_want, * since we always read a whole datagram at once. * * For DTLS, it is up to the caller to set ssl->next_record_offset when * they're done reading a record. */ int mbedtls_ssl_fetch_input(mbedtls_ssl_context *ssl, size_t nb_want) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t len; #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) size_t in_buf_len = ssl->in_buf_len; #else size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN; #endif MBEDTLS_SSL_DEBUG_MSG(2, ("=> fetch input")); if (ssl->f_recv == NULL && ssl->f_recv_timeout == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("Bad usage of mbedtls_ssl_set_bio() ")); return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } if (nb_want > in_buf_len - (size_t) (ssl->in_hdr - ssl->in_buf)) { MBEDTLS_SSL_DEBUG_MSG(1, ("requesting more data than fits")); return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { uint32_t timeout; /* * The point is, we need to always read a full datagram at once, so we * sometimes read more then requested, and handle the additional data. * It could be the rest of the current record (while fetching the * header) and/or some other records in the same datagram. */ /* * Move to the next record in the already read datagram if applicable */ if (ssl->next_record_offset != 0) { if (ssl->in_left < ssl->next_record_offset) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } ssl->in_left -= ssl->next_record_offset; if (ssl->in_left != 0) { MBEDTLS_SSL_DEBUG_MSG(2, ("next record in same datagram, offset: %" MBEDTLS_PRINTF_SIZET, ssl->next_record_offset)); memmove(ssl->in_hdr, ssl->in_hdr + ssl->next_record_offset, ssl->in_left); } ssl->next_record_offset = 0; } MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET ", nb_want: %" MBEDTLS_PRINTF_SIZET, ssl->in_left, nb_want)); /* * Done if we already have enough data. */ if (nb_want <= ssl->in_left) { MBEDTLS_SSL_DEBUG_MSG(2, ("<= fetch input")); return 0; } /* * A record can't be split across datagrams. If we need to read but * are not at the beginning of a new record, the caller did something * wrong. */ if (ssl->in_left != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* * Don't even try to read if time's out already. * This avoids by-passing the timer when repeatedly receiving messages * that will end up being dropped. */ if (mbedtls_ssl_check_timer(ssl) != 0) { MBEDTLS_SSL_DEBUG_MSG(2, ("timer has expired")); ret = MBEDTLS_ERR_SSL_TIMEOUT; } else { len = in_buf_len - (ssl->in_hdr - ssl->in_buf); if (mbedtls_ssl_is_handshake_over(ssl) == 0) { timeout = ssl->handshake->retransmit_timeout; } else { timeout = ssl->conf->read_timeout; } MBEDTLS_SSL_DEBUG_MSG(3, ("f_recv_timeout: %lu ms", (unsigned long) timeout)); if (ssl->f_recv_timeout != NULL) { ret = ssl->f_recv_timeout(ssl->p_bio, ssl->in_hdr, len, timeout); } else { ret = ssl->f_recv(ssl->p_bio, ssl->in_hdr, len); } MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_recv(_timeout)", ret); if (ret == 0) { return MBEDTLS_ERR_SSL_CONN_EOF; } } if (ret == MBEDTLS_ERR_SSL_TIMEOUT) { MBEDTLS_SSL_DEBUG_MSG(2, ("timeout")); mbedtls_ssl_set_timer(ssl, 0); if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) { if (ssl_double_retransmit_timeout(ssl) != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("handshake timeout")); return MBEDTLS_ERR_SSL_TIMEOUT; } if ((ret = mbedtls_ssl_resend(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend", ret); return ret; } return MBEDTLS_ERR_SSL_WANT_READ; } #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION) else if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER && ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) { if ((ret = mbedtls_ssl_resend_hello_request(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend_hello_request", ret); return ret; } return MBEDTLS_ERR_SSL_WANT_READ; } #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */ } if (ret < 0) { return ret; } ssl->in_left = ret; } else #endif { MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET ", nb_want: %" MBEDTLS_PRINTF_SIZET, ssl->in_left, nb_want)); while (ssl->in_left < nb_want) { len = nb_want - ssl->in_left; if (mbedtls_ssl_check_timer(ssl) != 0) { ret = MBEDTLS_ERR_SSL_TIMEOUT; } else { if (ssl->f_recv_timeout != NULL) { ret = ssl->f_recv_timeout(ssl->p_bio, ssl->in_hdr + ssl->in_left, len, ssl->conf->read_timeout); } else { ret = ssl->f_recv(ssl->p_bio, ssl->in_hdr + ssl->in_left, len); } } MBEDTLS_SSL_DEBUG_MSG(2, ("in_left: %" MBEDTLS_PRINTF_SIZET ", nb_want: %" MBEDTLS_PRINTF_SIZET, ssl->in_left, nb_want)); MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_recv(_timeout)", ret); if (ret == 0) { return MBEDTLS_ERR_SSL_CONN_EOF; } if (ret < 0) { return ret; } if ((size_t) ret > len) { MBEDTLS_SSL_DEBUG_MSG(1, ("f_recv returned %d bytes but only %" MBEDTLS_PRINTF_SIZET " were requested", ret, len)); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } ssl->in_left += ret; } } MBEDTLS_SSL_DEBUG_MSG(2, ("<= fetch input")); return 0; } /* * Flush any data not yet written */ int mbedtls_ssl_flush_output(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *buf; MBEDTLS_SSL_DEBUG_MSG(2, ("=> flush output")); if (ssl->f_send == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("Bad usage of mbedtls_ssl_set_bio() ")); return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } /* Avoid incrementing counter if data is flushed */ if (ssl->out_left == 0) { MBEDTLS_SSL_DEBUG_MSG(2, ("<= flush output")); return 0; } while (ssl->out_left > 0) { MBEDTLS_SSL_DEBUG_MSG(2, ("message length: %" MBEDTLS_PRINTF_SIZET ", out_left: %" MBEDTLS_PRINTF_SIZET, mbedtls_ssl_out_hdr_len(ssl) + ssl->out_msglen, ssl->out_left)); buf = ssl->out_hdr - ssl->out_left; ret = ssl->f_send(ssl->p_bio, buf, ssl->out_left); MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_send", ret); if (ret <= 0) { return ret; } if ((size_t) ret > ssl->out_left) { MBEDTLS_SSL_DEBUG_MSG(1, ("f_send returned %d bytes but only %" MBEDTLS_PRINTF_SIZET " bytes were sent", ret, ssl->out_left)); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } ssl->out_left -= ret; } #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { ssl->out_hdr = ssl->out_buf; } else #endif { ssl->out_hdr = ssl->out_buf + 8; } mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out); MBEDTLS_SSL_DEBUG_MSG(2, ("<= flush output")); return 0; } /* * Functions to handle the DTLS retransmission state machine */ #if defined(MBEDTLS_SSL_PROTO_DTLS) /* * Append current handshake message to current outgoing flight */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_flight_append(mbedtls_ssl_context *ssl) { mbedtls_ssl_flight_item *msg; MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_flight_append")); MBEDTLS_SSL_DEBUG_BUF(4, "message appended to flight", ssl->out_msg, ssl->out_msglen); /* Allocate space for current message */ if ((msg = mbedtls_calloc(1, sizeof(mbedtls_ssl_flight_item))) == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("alloc %" MBEDTLS_PRINTF_SIZET " bytes failed", sizeof(mbedtls_ssl_flight_item))); return MBEDTLS_ERR_SSL_ALLOC_FAILED; } if ((msg->p = mbedtls_calloc(1, ssl->out_msglen)) == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("alloc %" MBEDTLS_PRINTF_SIZET " bytes failed", ssl->out_msglen)); mbedtls_free(msg); return MBEDTLS_ERR_SSL_ALLOC_FAILED; } /* Copy current handshake message with headers */ memcpy(msg->p, ssl->out_msg, ssl->out_msglen); msg->len = ssl->out_msglen; msg->type = ssl->out_msgtype; msg->next = NULL; /* Append to the current flight */ if (ssl->handshake->flight == NULL) { ssl->handshake->flight = msg; } else { mbedtls_ssl_flight_item *cur = ssl->handshake->flight; while (cur->next != NULL) { cur = cur->next; } cur->next = msg; } MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_flight_append")); return 0; } /* * Free the current flight of handshake messages */ void mbedtls_ssl_flight_free(mbedtls_ssl_flight_item *flight) { mbedtls_ssl_flight_item *cur = flight; mbedtls_ssl_flight_item *next; while (cur != NULL) { next = cur->next; mbedtls_free(cur->p); mbedtls_free(cur); cur = next; } } /* * Swap transform_out and out_ctr with the alternative ones */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_swap_epochs(mbedtls_ssl_context *ssl) { mbedtls_ssl_transform *tmp_transform; unsigned char tmp_out_ctr[MBEDTLS_SSL_SEQUENCE_NUMBER_LEN]; if (ssl->transform_out == ssl->handshake->alt_transform_out) { MBEDTLS_SSL_DEBUG_MSG(3, ("skip swap epochs")); return 0; } MBEDTLS_SSL_DEBUG_MSG(3, ("swap epochs")); /* Swap transforms */ tmp_transform = ssl->transform_out; ssl->transform_out = ssl->handshake->alt_transform_out; ssl->handshake->alt_transform_out = tmp_transform; /* Swap epoch + sequence_number */ memcpy(tmp_out_ctr, ssl->cur_out_ctr, sizeof(tmp_out_ctr)); memcpy(ssl->cur_out_ctr, ssl->handshake->alt_out_ctr, sizeof(ssl->cur_out_ctr)); memcpy(ssl->handshake->alt_out_ctr, tmp_out_ctr, sizeof(ssl->handshake->alt_out_ctr)); /* Adjust to the newly activated transform */ mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out); return 0; } /* * Retransmit the current flight of messages. */ int mbedtls_ssl_resend(mbedtls_ssl_context *ssl) { int ret = 0; MBEDTLS_SSL_DEBUG_MSG(2, ("=> mbedtls_ssl_resend")); ret = mbedtls_ssl_flight_transmit(ssl); MBEDTLS_SSL_DEBUG_MSG(2, ("<= mbedtls_ssl_resend")); return ret; } /* * Transmit or retransmit the current flight of messages. * * Need to remember the current message in case flush_output returns * WANT_WRITE, causing us to exit this function and come back later. * This function must be called until state is no longer SENDING. */ int mbedtls_ssl_flight_transmit(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG(2, ("=> mbedtls_ssl_flight_transmit")); if (ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING) { MBEDTLS_SSL_DEBUG_MSG(2, ("initialise flight transmission")); ssl->handshake->cur_msg = ssl->handshake->flight; ssl->handshake->cur_msg_p = ssl->handshake->flight->p + 12; ret = ssl_swap_epochs(ssl); if (ret != 0) { return ret; } ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_SENDING; } while (ssl->handshake->cur_msg != NULL) { size_t max_frag_len; const mbedtls_ssl_flight_item * const cur = ssl->handshake->cur_msg; int const is_finished = (cur->type == MBEDTLS_SSL_MSG_HANDSHAKE && cur->p[0] == MBEDTLS_SSL_HS_FINISHED); int const force_flush = ssl->disable_datagram_packing == 1 ? SSL_FORCE_FLUSH : SSL_DONT_FORCE_FLUSH; /* Swap epochs before sending Finished: we can't do it after * sending ChangeCipherSpec, in case write returns WANT_READ. * Must be done before copying, may change out_msg pointer */ if (is_finished && ssl->handshake->cur_msg_p == (cur->p + 12)) { MBEDTLS_SSL_DEBUG_MSG(2, ("swap epochs to send finished message")); ret = ssl_swap_epochs(ssl); if (ret != 0) { return ret; } } ret = ssl_get_remaining_payload_in_datagram(ssl); if (ret < 0) { return ret; } max_frag_len = (size_t) ret; /* CCS is copied as is, while HS messages may need fragmentation */ if (cur->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { if (max_frag_len == 0) { if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { return ret; } continue; } memcpy(ssl->out_msg, cur->p, cur->len); ssl->out_msglen = cur->len; ssl->out_msgtype = cur->type; /* Update position inside current message */ ssl->handshake->cur_msg_p += cur->len; } else { const unsigned char * const p = ssl->handshake->cur_msg_p; const size_t hs_len = cur->len - 12; const size_t frag_off = p - (cur->p + 12); const size_t rem_len = hs_len - frag_off; size_t cur_hs_frag_len, max_hs_frag_len; if ((max_frag_len < 12) || (max_frag_len == 12 && hs_len != 0)) { if (is_finished) { ret = ssl_swap_epochs(ssl); if (ret != 0) { return ret; } } if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { return ret; } continue; } max_hs_frag_len = max_frag_len - 12; cur_hs_frag_len = rem_len > max_hs_frag_len ? max_hs_frag_len : rem_len; if (frag_off == 0 && cur_hs_frag_len != hs_len) { MBEDTLS_SSL_DEBUG_MSG(2, ("fragmenting handshake message (%u > %u)", (unsigned) cur_hs_frag_len, (unsigned) max_hs_frag_len)); } /* Messages are stored with handshake headers as if not fragmented, * copy beginning of headers then fill fragmentation fields. * Handshake headers: type(1) len(3) seq(2) f_off(3) f_len(3) */ memcpy(ssl->out_msg, cur->p, 6); ssl->out_msg[6] = MBEDTLS_BYTE_2(frag_off); ssl->out_msg[7] = MBEDTLS_BYTE_1(frag_off); ssl->out_msg[8] = MBEDTLS_BYTE_0(frag_off); ssl->out_msg[9] = MBEDTLS_BYTE_2(cur_hs_frag_len); ssl->out_msg[10] = MBEDTLS_BYTE_1(cur_hs_frag_len); ssl->out_msg[11] = MBEDTLS_BYTE_0(cur_hs_frag_len); MBEDTLS_SSL_DEBUG_BUF(3, "handshake header", ssl->out_msg, 12); /* Copy the handshake message content and set records fields */ memcpy(ssl->out_msg + 12, p, cur_hs_frag_len); ssl->out_msglen = cur_hs_frag_len + 12; ssl->out_msgtype = cur->type; /* Update position inside current message */ ssl->handshake->cur_msg_p += cur_hs_frag_len; } /* If done with the current message move to the next one if any */ if (ssl->handshake->cur_msg_p >= cur->p + cur->len) { if (cur->next != NULL) { ssl->handshake->cur_msg = cur->next; ssl->handshake->cur_msg_p = cur->next->p + 12; } else { ssl->handshake->cur_msg = NULL; ssl->handshake->cur_msg_p = NULL; } } /* Actually send the message out */ if ((ret = mbedtls_ssl_write_record(ssl, force_flush)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret); return ret; } } if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { return ret; } /* Update state and set timer */ if (mbedtls_ssl_is_handshake_over(ssl) == 1) { ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED; } else { ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING; mbedtls_ssl_set_timer(ssl, ssl->handshake->retransmit_timeout); } MBEDTLS_SSL_DEBUG_MSG(2, ("<= mbedtls_ssl_flight_transmit")); return 0; } /* * To be called when the last message of an incoming flight is received. */ void mbedtls_ssl_recv_flight_completed(mbedtls_ssl_context *ssl) { /* We won't need to resend that one any more */ mbedtls_ssl_flight_free(ssl->handshake->flight); ssl->handshake->flight = NULL; ssl->handshake->cur_msg = NULL; /* The next incoming flight will start with this msg_seq */ ssl->handshake->in_flight_start_seq = ssl->handshake->in_msg_seq; /* We don't want to remember CCS's across flight boundaries. */ ssl->handshake->buffering.seen_ccs = 0; /* Clear future message buffering structure. */ mbedtls_ssl_buffering_free(ssl); /* Cancel timer */ mbedtls_ssl_set_timer(ssl, 0); if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED) { ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED; } else { ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING; } } /* * To be called when the last message of an outgoing flight is send. */ void mbedtls_ssl_send_flight_completed(mbedtls_ssl_context *ssl) { ssl_reset_retransmit_timeout(ssl); mbedtls_ssl_set_timer(ssl, ssl->handshake->retransmit_timeout); if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED) { ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED; } else { ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING; } } #endif /* MBEDTLS_SSL_PROTO_DTLS */ /* * Handshake layer functions */ int mbedtls_ssl_start_handshake_msg(mbedtls_ssl_context *ssl, unsigned hs_type, unsigned char **buf, size_t *buf_len) { /* * Reserve 4 bytes for handshake header. ( Section 4,RFC 8446 ) * ... * HandshakeType msg_type; * uint24 length; * ... */ *buf = ssl->out_msg + 4; *buf_len = MBEDTLS_SSL_OUT_CONTENT_LEN - 4; ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE; ssl->out_msg[0] = hs_type; return 0; } /* * Write (DTLS: or queue) current handshake (including CCS) message. * * - fill in handshake headers * - update handshake checksum * - DTLS: save message for resending * - then pass to the record layer * * DTLS: except for HelloRequest, messages are only queued, and will only be * actually sent when calling flight_transmit() or resend(). * * Inputs: * - ssl->out_msglen: 4 + actual handshake message len * (4 is the size of handshake headers for TLS) * - ssl->out_msg[0]: the handshake type (ClientHello, ServerHello, etc) * - ssl->out_msg + 4: the handshake message body * * Outputs, ie state before passing to flight_append() or write_record(): * - ssl->out_msglen: the length of the record contents * (including handshake headers but excluding record headers) * - ssl->out_msg: the record contents (handshake headers + content) */ int mbedtls_ssl_write_handshake_msg_ext(mbedtls_ssl_context *ssl, int update_checksum, int force_flush) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; const size_t hs_len = ssl->out_msglen - 4; const unsigned char hs_type = ssl->out_msg[0]; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write handshake message")); /* * Sanity checks */ if (ssl->out_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE && ssl->out_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* Whenever we send anything different from a * HelloRequest we should be in a handshake - double check. */ if (!(ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST) && ssl->handshake == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && ssl->handshake != NULL && ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } #endif /* Double-check that we did not exceed the bounds * of the outgoing record buffer. * This should never fail as the various message * writing functions must obey the bounds of the * outgoing record buffer, but better be safe. * * Note: We deliberately do not check for the MTU or MFL here. */ if (ssl->out_msglen > MBEDTLS_SSL_OUT_CONTENT_LEN) { MBEDTLS_SSL_DEBUG_MSG(1, ("Record too large: " "size %" MBEDTLS_PRINTF_SIZET ", maximum %" MBEDTLS_PRINTF_SIZET, ssl->out_msglen, (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN)); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* * Fill handshake headers */ if (ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) { ssl->out_msg[1] = MBEDTLS_BYTE_2(hs_len); ssl->out_msg[2] = MBEDTLS_BYTE_1(hs_len); ssl->out_msg[3] = MBEDTLS_BYTE_0(hs_len); /* * DTLS has additional fields in the Handshake layer, * between the length field and the actual payload: * uint16 message_seq; * uint24 fragment_offset; * uint24 fragment_length; */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { /* Make room for the additional DTLS fields */ if (MBEDTLS_SSL_OUT_CONTENT_LEN - ssl->out_msglen < 8) { MBEDTLS_SSL_DEBUG_MSG(1, ("DTLS handshake message too large: " "size %" MBEDTLS_PRINTF_SIZET ", maximum %" MBEDTLS_PRINTF_SIZET, hs_len, (size_t) (MBEDTLS_SSL_OUT_CONTENT_LEN - 12))); return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } memmove(ssl->out_msg + 12, ssl->out_msg + 4, hs_len); ssl->out_msglen += 8; /* Write message_seq and update it, except for HelloRequest */ if (hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST) { MBEDTLS_PUT_UINT16_BE(ssl->handshake->out_msg_seq, ssl->out_msg, 4); ++(ssl->handshake->out_msg_seq); } else { ssl->out_msg[4] = 0; ssl->out_msg[5] = 0; } /* Handshake hashes are computed without fragmentation, * so set frag_offset = 0 and frag_len = hs_len for now */ memset(ssl->out_msg + 6, 0x00, 3); memcpy(ssl->out_msg + 9, ssl->out_msg + 1, 3); } #endif /* MBEDTLS_SSL_PROTO_DTLS */ /* Update running hashes of handshake messages seen */ if (hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST && update_checksum != 0) { ret = ssl->handshake->update_checksum(ssl, ssl->out_msg, ssl->out_msglen); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret); return ret; } } } /* Either send now, or just save to be sent (and resent) later */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && !(ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST)) { if ((ret = ssl_flight_append(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_flight_append", ret); return ret; } } else #endif { if ((ret = mbedtls_ssl_write_record(ssl, force_flush)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_write_record", ret); return ret; } } MBEDTLS_SSL_DEBUG_MSG(2, ("<= write handshake message")); return 0; } int mbedtls_ssl_finish_handshake_msg(mbedtls_ssl_context *ssl, size_t buf_len, size_t msg_len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t msg_with_header_len; ((void) buf_len); /* Add reserved 4 bytes for handshake header */ msg_with_header_len = msg_len + 4; ssl->out_msglen = msg_with_header_len; MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_write_handshake_msg_ext(ssl, 0, 0)); cleanup: return ret; } /* * Record layer functions */ /* * Write current record. * * Uses: * - ssl->out_msgtype: type of the message (AppData, Handshake, Alert, CCS) * - ssl->out_msglen: length of the record content (excl headers) * - ssl->out_msg: record content */ int mbedtls_ssl_write_record(mbedtls_ssl_context *ssl, int force_flush) { int ret, done = 0; size_t len = ssl->out_msglen; int flush = force_flush; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write record")); if (!done) { unsigned i; size_t protected_record_size; #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) size_t out_buf_len = ssl->out_buf_len; #else size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN; #endif /* Skip writing the record content type to after the encryption, * as it may change when using the CID extension. */ mbedtls_ssl_protocol_version tls_ver = ssl->tls_version; #if defined(MBEDTLS_SSL_PROTO_TLS1_3) /* TLS 1.3 still uses the TLS 1.2 version identifier * for backwards compatibility. */ if (tls_ver == MBEDTLS_SSL_VERSION_TLS1_3) { tls_ver = MBEDTLS_SSL_VERSION_TLS1_2; } #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ mbedtls_ssl_write_version(ssl->out_hdr + 1, ssl->conf->transport, tls_ver); memcpy(ssl->out_ctr, ssl->cur_out_ctr, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN); MBEDTLS_PUT_UINT16_BE(len, ssl->out_len, 0); if (ssl->transform_out != NULL) { mbedtls_record rec; rec.buf = ssl->out_iv; rec.buf_len = out_buf_len - (ssl->out_iv - ssl->out_buf); rec.data_len = ssl->out_msglen; rec.data_offset = ssl->out_msg - rec.buf; memcpy(&rec.ctr[0], ssl->out_ctr, sizeof(rec.ctr)); mbedtls_ssl_write_version(rec.ver, ssl->conf->transport, tls_ver); rec.type = ssl->out_msgtype; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) /* The CID is set by mbedtls_ssl_encrypt_buf(). */ rec.cid_len = 0; #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ if ((ret = mbedtls_ssl_encrypt_buf(ssl, ssl->transform_out, &rec, ssl->conf->f_rng, ssl->conf->p_rng)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_encrypt_buf", ret); return ret; } if (rec.data_offset != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* Update the record content type and CID. */ ssl->out_msgtype = rec.type; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) memcpy(ssl->out_cid, rec.cid, rec.cid_len); #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ ssl->out_msglen = len = rec.data_len; MBEDTLS_PUT_UINT16_BE(rec.data_len, ssl->out_len, 0); } protected_record_size = len + mbedtls_ssl_out_hdr_len(ssl); #if defined(MBEDTLS_SSL_PROTO_DTLS) /* In case of DTLS, double-check that we don't exceed * the remaining space in the datagram. */ if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { ret = ssl_get_remaining_space_in_datagram(ssl); if (ret < 0) { return ret; } if (protected_record_size > (size_t) ret) { /* Should never happen */ return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } } #endif /* MBEDTLS_SSL_PROTO_DTLS */ /* Now write the potentially updated record content type. */ ssl->out_hdr[0] = (unsigned char) ssl->out_msgtype; MBEDTLS_SSL_DEBUG_MSG(3, ("output record: msgtype = %u, " "version = [%u:%u], msglen = %" MBEDTLS_PRINTF_SIZET, ssl->out_hdr[0], ssl->out_hdr[1], ssl->out_hdr[2], len)); MBEDTLS_SSL_DEBUG_BUF(4, "output record sent to network", ssl->out_hdr, protected_record_size); ssl->out_left += protected_record_size; ssl->out_hdr += protected_record_size; mbedtls_ssl_update_out_pointers(ssl, ssl->transform_out); for (i = 8; i > mbedtls_ssl_ep_len(ssl); i--) { if (++ssl->cur_out_ctr[i - 1] != 0) { break; } } /* The loop goes to its end if the counter is wrapping */ if (i == mbedtls_ssl_ep_len(ssl)) { MBEDTLS_SSL_DEBUG_MSG(1, ("outgoing message counter would wrap")); return MBEDTLS_ERR_SSL_COUNTER_WRAPPING; } } #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && flush == SSL_DONT_FORCE_FLUSH) { size_t remaining; ret = ssl_get_remaining_payload_in_datagram(ssl); if (ret < 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_get_remaining_payload_in_datagram", ret); return ret; } remaining = (size_t) ret; if (remaining == 0) { flush = SSL_FORCE_FLUSH; } else { MBEDTLS_SSL_DEBUG_MSG(2, ("Still %u bytes available in current datagram", (unsigned) remaining)); } } #endif /* MBEDTLS_SSL_PROTO_DTLS */ if ((flush == SSL_FORCE_FLUSH) && (ret = mbedtls_ssl_flush_output(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flush_output", ret); return ret; } MBEDTLS_SSL_DEBUG_MSG(2, ("<= write record")); return 0; } #if defined(MBEDTLS_SSL_PROTO_DTLS) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_hs_is_proper_fragment(mbedtls_ssl_context *ssl) { if (ssl->in_msglen < ssl->in_hslen || memcmp(ssl->in_msg + 6, "\0\0\0", 3) != 0 || memcmp(ssl->in_msg + 9, ssl->in_msg + 1, 3) != 0) { return 1; } return 0; } static uint32_t ssl_get_hs_frag_len(mbedtls_ssl_context const *ssl) { return (ssl->in_msg[9] << 16) | (ssl->in_msg[10] << 8) | ssl->in_msg[11]; } static uint32_t ssl_get_hs_frag_off(mbedtls_ssl_context const *ssl) { return (ssl->in_msg[6] << 16) | (ssl->in_msg[7] << 8) | ssl->in_msg[8]; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_check_hs_header(mbedtls_ssl_context const *ssl) { uint32_t msg_len, frag_off, frag_len; msg_len = ssl_get_hs_total_len(ssl); frag_off = ssl_get_hs_frag_off(ssl); frag_len = ssl_get_hs_frag_len(ssl); if (frag_off > msg_len) { return -1; } if (frag_len > msg_len - frag_off) { return -1; } if (frag_len + 12 > ssl->in_msglen) { return -1; } return 0; } /* * Mark bits in bitmask (used for DTLS HS reassembly) */ static void ssl_bitmask_set(unsigned char *mask, size_t offset, size_t len) { unsigned int start_bits, end_bits; start_bits = 8 - (offset % 8); if (start_bits != 8) { size_t first_byte_idx = offset / 8; /* Special case */ if (len <= start_bits) { for (; len != 0; len--) { mask[first_byte_idx] |= 1 << (start_bits - len); } /* Avoid potential issues with offset or len becoming invalid */ return; } offset += start_bits; /* Now offset % 8 == 0 */ len -= start_bits; for (; start_bits != 0; start_bits--) { mask[first_byte_idx] |= 1 << (start_bits - 1); } } end_bits = len % 8; if (end_bits != 0) { size_t last_byte_idx = (offset + len) / 8; len -= end_bits; /* Now len % 8 == 0 */ for (; end_bits != 0; end_bits--) { mask[last_byte_idx] |= 1 << (8 - end_bits); } } memset(mask + offset / 8, 0xFF, len / 8); } /* * Check that bitmask is full */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_bitmask_check(unsigned char *mask, size_t len) { size_t i; for (i = 0; i < len / 8; i++) { if (mask[i] != 0xFF) { return -1; } } for (i = 0; i < len % 8; i++) { if ((mask[len / 8] & (1 << (7 - i))) == 0) { return -1; } } return 0; } /* msg_len does not include the handshake header */ static size_t ssl_get_reassembly_buffer_size(size_t msg_len, unsigned add_bitmap) { size_t alloc_len; alloc_len = 12; /* Handshake header */ alloc_len += msg_len; /* Content buffer */ if (add_bitmap) { alloc_len += msg_len / 8 + (msg_len % 8 != 0); /* Bitmap */ } return alloc_len; } #endif /* MBEDTLS_SSL_PROTO_DTLS */ static uint32_t ssl_get_hs_total_len(mbedtls_ssl_context const *ssl) { return (ssl->in_msg[1] << 16) | (ssl->in_msg[2] << 8) | ssl->in_msg[3]; } int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl) { if (ssl->in_msglen < mbedtls_ssl_hs_hdr_len(ssl)) { MBEDTLS_SSL_DEBUG_MSG(1, ("handshake message too short: %" MBEDTLS_PRINTF_SIZET, ssl->in_msglen)); return MBEDTLS_ERR_SSL_INVALID_RECORD; } ssl->in_hslen = mbedtls_ssl_hs_hdr_len(ssl) + ssl_get_hs_total_len(ssl); MBEDTLS_SSL_DEBUG_MSG(3, ("handshake message: msglen =" " %" MBEDTLS_PRINTF_SIZET ", type = %u, hslen = %" MBEDTLS_PRINTF_SIZET, ssl->in_msglen, ssl->in_msg[0], ssl->in_hslen)); #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned int recv_msg_seq = (ssl->in_msg[4] << 8) | ssl->in_msg[5]; if (ssl_check_hs_header(ssl) != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("invalid handshake header")); return MBEDTLS_ERR_SSL_INVALID_RECORD; } if (ssl->handshake != NULL && ((mbedtls_ssl_is_handshake_over(ssl) == 0 && recv_msg_seq != ssl->handshake->in_msg_seq) || (mbedtls_ssl_is_handshake_over(ssl) == 1 && ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO))) { if (recv_msg_seq > ssl->handshake->in_msg_seq) { MBEDTLS_SSL_DEBUG_MSG(2, ( "received future handshake message of sequence number %u (next %u)", recv_msg_seq, ssl->handshake->in_msg_seq)); return MBEDTLS_ERR_SSL_EARLY_MESSAGE; } /* Retransmit only on last message from previous flight, to avoid * too many retransmissions. * Besides, No sane server ever retransmits HelloVerifyRequest */ if (recv_msg_seq == ssl->handshake->in_flight_start_seq - 1 && ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST) { MBEDTLS_SSL_DEBUG_MSG(2, ("received message from last flight, " "message_seq = %u, start_of_flight = %u", recv_msg_seq, ssl->handshake->in_flight_start_seq)); if ((ret = mbedtls_ssl_resend(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend", ret); return ret; } } else { MBEDTLS_SSL_DEBUG_MSG(2, ("dropping out-of-sequence message: " "message_seq = %u, expected = %u", recv_msg_seq, ssl->handshake->in_msg_seq)); } return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; } /* Wait until message completion to increment in_msg_seq */ /* Message reassembly is handled alongside buffering of future * messages; the commonality is that both handshake fragments and * future messages cannot be forwarded immediately to the * handshake logic layer. */ if (ssl_hs_is_proper_fragment(ssl) == 1) { MBEDTLS_SSL_DEBUG_MSG(2, ("found fragmented DTLS handshake message")); return MBEDTLS_ERR_SSL_EARLY_MESSAGE; } } else #endif /* MBEDTLS_SSL_PROTO_DTLS */ /* With TLS we don't handle fragmentation (for now) */ if (ssl->in_msglen < ssl->in_hslen) { MBEDTLS_SSL_DEBUG_MSG(1, ("TLS handshake fragmentation not supported")); return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE; } return 0; } int mbedtls_ssl_update_handshake_status(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_handshake_params * const hs = ssl->handshake; if (mbedtls_ssl_is_handshake_over(ssl) == 0 && hs != NULL) { ret = ssl->handshake->update_checksum(ssl, ssl->in_msg, ssl->in_hslen); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret); return ret; } } /* Handshake message is complete, increment counter */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && ssl->handshake != NULL) { unsigned offset; mbedtls_ssl_hs_buffer *hs_buf; /* Increment handshake sequence number */ hs->in_msg_seq++; /* * Clear up handshake buffering and reassembly structure. */ /* Free first entry */ ssl_buffering_free_slot(ssl, 0); /* Shift all other entries */ for (offset = 0, hs_buf = &hs->buffering.hs[0]; offset + 1 < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++, hs_buf++) { *hs_buf = *(hs_buf + 1); } /* Create a fresh last entry */ memset(hs_buf, 0, sizeof(mbedtls_ssl_hs_buffer)); } #endif return 0; } /* * DTLS anti-replay: RFC 6347 4.1.2.6 * * in_window is a field of bits numbered from 0 (lsb) to 63 (msb). * Bit n is set iff record number in_window_top - n has been seen. * * Usually, in_window_top is the last record number seen and the lsb of * in_window is set. The only exception is the initial state (record number 0 * not seen yet). */ #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) void mbedtls_ssl_dtls_replay_reset(mbedtls_ssl_context *ssl) { ssl->in_window_top = 0; ssl->in_window = 0; } static inline uint64_t ssl_load_six_bytes(unsigned char *buf) { return ((uint64_t) buf[0] << 40) | ((uint64_t) buf[1] << 32) | ((uint64_t) buf[2] << 24) | ((uint64_t) buf[3] << 16) | ((uint64_t) buf[4] << 8) | ((uint64_t) buf[5]); } MBEDTLS_CHECK_RETURN_CRITICAL static int mbedtls_ssl_dtls_record_replay_check(mbedtls_ssl_context *ssl, uint8_t *record_in_ctr) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char *original_in_ctr; // save original in_ctr original_in_ctr = ssl->in_ctr; // use counter from record ssl->in_ctr = record_in_ctr; ret = mbedtls_ssl_dtls_replay_check((mbedtls_ssl_context const *) ssl); // restore the counter ssl->in_ctr = original_in_ctr; return ret; } /* * Return 0 if sequence number is acceptable, -1 otherwise */ int mbedtls_ssl_dtls_replay_check(mbedtls_ssl_context const *ssl) { uint64_t rec_seqnum = ssl_load_six_bytes(ssl->in_ctr + 2); uint64_t bit; if (ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED) { return 0; } if (rec_seqnum > ssl->in_window_top) { return 0; } bit = ssl->in_window_top - rec_seqnum; if (bit >= 64) { return -1; } if ((ssl->in_window & ((uint64_t) 1 << bit)) != 0) { return -1; } return 0; } /* * Update replay window on new validated record */ void mbedtls_ssl_dtls_replay_update(mbedtls_ssl_context *ssl) { uint64_t rec_seqnum = ssl_load_six_bytes(ssl->in_ctr + 2); if (ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED) { return; } if (rec_seqnum > ssl->in_window_top) { /* Update window_top and the contents of the window */ uint64_t shift = rec_seqnum - ssl->in_window_top; if (shift >= 64) { ssl->in_window = 1; } else { ssl->in_window <<= shift; ssl->in_window |= 1; } ssl->in_window_top = rec_seqnum; } else { /* Mark that number as seen in the current window */ uint64_t bit = ssl->in_window_top - rec_seqnum; if (bit < 64) { /* Always true, but be extra sure */ ssl->in_window |= (uint64_t) 1 << bit; } } } #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */ #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C) /* * Check if a datagram looks like a ClientHello with a valid cookie, * and if it doesn't, generate a HelloVerifyRequest message. * Both input and output include full DTLS headers. * * - if cookie is valid, return 0 * - if ClientHello looks superficially valid but cookie is not, * fill obuf and set olen, then * return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED * - otherwise return a specific error code */ MBEDTLS_CHECK_RETURN_CRITICAL MBEDTLS_STATIC_TESTABLE int mbedtls_ssl_check_dtls_clihlo_cookie( mbedtls_ssl_context *ssl, const unsigned char *cli_id, size_t cli_id_len, const unsigned char *in, size_t in_len, unsigned char *obuf, size_t buf_len, size_t *olen) { size_t sid_len, cookie_len, epoch, fragment_offset; unsigned char *p; /* * Structure of ClientHello with record and handshake headers, * and expected values. We don't need to check a lot, more checks will be * done when actually parsing the ClientHello - skipping those checks * avoids code duplication and does not make cookie forging any easier. * * 0-0 ContentType type; copied, must be handshake * 1-2 ProtocolVersion version; copied * 3-4 uint16 epoch; copied, must be 0 * 5-10 uint48 sequence_number; copied * 11-12 uint16 length; (ignored) * * 13-13 HandshakeType msg_type; (ignored) * 14-16 uint24 length; (ignored) * 17-18 uint16 message_seq; copied * 19-21 uint24 fragment_offset; copied, must be 0 * 22-24 uint24 fragment_length; (ignored) * * 25-26 ProtocolVersion client_version; (ignored) * 27-58 Random random; (ignored) * 59-xx SessionID session_id; 1 byte len + sid_len content * 60+ opaque cookie<0..2^8-1>; 1 byte len + content * ... * * Minimum length is 61 bytes. */ MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: in_len=%u", (unsigned) in_len)); MBEDTLS_SSL_DEBUG_BUF(4, "cli_id", cli_id, cli_id_len); if (in_len < 61) { MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: record too short")); return MBEDTLS_ERR_SSL_DECODE_ERROR; } epoch = MBEDTLS_GET_UINT16_BE(in, 3); fragment_offset = MBEDTLS_GET_UINT24_BE(in, 19); if (in[0] != MBEDTLS_SSL_MSG_HANDSHAKE || epoch != 0 || fragment_offset != 0) { MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: not a good ClientHello")); MBEDTLS_SSL_DEBUG_MSG(4, (" type=%u epoch=%u fragment_offset=%u", in[0], (unsigned) epoch, (unsigned) fragment_offset)); return MBEDTLS_ERR_SSL_DECODE_ERROR; } sid_len = in[59]; if (59 + 1 + sid_len + 1 > in_len) { MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: sid_len=%u > %u", (unsigned) sid_len, (unsigned) in_len - 61)); return MBEDTLS_ERR_SSL_DECODE_ERROR; } MBEDTLS_SSL_DEBUG_BUF(4, "sid received from network", in + 60, sid_len); cookie_len = in[60 + sid_len]; if (59 + 1 + sid_len + 1 + cookie_len > in_len) { MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: cookie_len=%u > %u", (unsigned) cookie_len, (unsigned) (in_len - sid_len - 61))); return MBEDTLS_ERR_SSL_DECODE_ERROR; } MBEDTLS_SSL_DEBUG_BUF(4, "cookie received from network", in + sid_len + 61, cookie_len); if (ssl->conf->f_cookie_check(ssl->conf->p_cookie, in + sid_len + 61, cookie_len, cli_id, cli_id_len) == 0) { MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: valid")); return 0; } /* * If we get here, we've got an invalid cookie, let's prepare HVR. * * 0-0 ContentType type; copied * 1-2 ProtocolVersion version; copied * 3-4 uint16 epoch; copied * 5-10 uint48 sequence_number; copied * 11-12 uint16 length; olen - 13 * * 13-13 HandshakeType msg_type; hello_verify_request * 14-16 uint24 length; olen - 25 * 17-18 uint16 message_seq; copied * 19-21 uint24 fragment_offset; copied * 22-24 uint24 fragment_length; olen - 25 * * 25-26 ProtocolVersion server_version; 0xfe 0xff * 27-27 opaque cookie<0..2^8-1>; cookie_len = olen - 27, cookie * * Minimum length is 28. */ if (buf_len < 28) { return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; } /* Copy most fields and adapt others */ memcpy(obuf, in, 25); obuf[13] = MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST; obuf[25] = 0xfe; obuf[26] = 0xff; /* Generate and write actual cookie */ p = obuf + 28; if (ssl->conf->f_cookie_write(ssl->conf->p_cookie, &p, obuf + buf_len, cli_id, cli_id_len) != 0) { return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } *olen = p - obuf; /* Go back and fill length fields */ obuf[27] = (unsigned char) (*olen - 28); obuf[14] = obuf[22] = MBEDTLS_BYTE_2(*olen - 25); obuf[15] = obuf[23] = MBEDTLS_BYTE_1(*olen - 25); obuf[16] = obuf[24] = MBEDTLS_BYTE_0(*olen - 25); MBEDTLS_PUT_UINT16_BE(*olen - 13, obuf, 11); return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED; } /* * Handle possible client reconnect with the same UDP quadruplet * (RFC 6347 Section 4.2.8). * * Called by ssl_parse_record_header() in case we receive an epoch 0 record * that looks like a ClientHello. * * - if the input looks like a ClientHello without cookies, * send back HelloVerifyRequest, then return 0 * - if the input looks like a ClientHello with a valid cookie, * reset the session of the current context, and * return MBEDTLS_ERR_SSL_CLIENT_RECONNECT * - if anything goes wrong, return a specific error code * * This function is called (through ssl_check_client_reconnect()) when an * unexpected record is found in ssl_get_next_record(), which will discard the * record if we return 0, and bubble up the return value otherwise (this * includes the case of MBEDTLS_ERR_SSL_CLIENT_RECONNECT and of unexpected * errors, and is the right thing to do in both cases). */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_handle_possible_reconnect(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t len; if (ssl->conf->f_cookie_write == NULL || ssl->conf->f_cookie_check == NULL) { /* If we can't use cookies to verify reachability of the peer, * drop the record. */ MBEDTLS_SSL_DEBUG_MSG(1, ("no cookie callbacks, " "can't check reconnect validity")); return 0; } ret = mbedtls_ssl_check_dtls_clihlo_cookie( ssl, ssl->cli_id, ssl->cli_id_len, ssl->in_buf, ssl->in_left, ssl->out_buf, MBEDTLS_SSL_OUT_CONTENT_LEN, &len); MBEDTLS_SSL_DEBUG_RET(2, "mbedtls_ssl_check_dtls_clihlo_cookie", ret); if (ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED) { int send_ret; MBEDTLS_SSL_DEBUG_MSG(1, ("sending HelloVerifyRequest")); MBEDTLS_SSL_DEBUG_BUF(4, "output record sent to network", ssl->out_buf, len); /* Don't check write errors as we can't do anything here. * If the error is permanent we'll catch it later, * if it's not, then hopefully it'll work next time. */ send_ret = ssl->f_send(ssl->p_bio, ssl->out_buf, len); MBEDTLS_SSL_DEBUG_RET(2, "ssl->f_send", send_ret); (void) send_ret; return 0; } if (ret == 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("cookie is valid, resetting context")); if ((ret = mbedtls_ssl_session_reset_int(ssl, 1)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "reset", ret); return ret; } return MBEDTLS_ERR_SSL_CLIENT_RECONNECT; } return ret; } #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_check_record_type(uint8_t record_type) { if (record_type != MBEDTLS_SSL_MSG_HANDSHAKE && record_type != MBEDTLS_SSL_MSG_ALERT && record_type != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC && record_type != MBEDTLS_SSL_MSG_APPLICATION_DATA) { return MBEDTLS_ERR_SSL_INVALID_RECORD; } return 0; } /* * ContentType type; * ProtocolVersion version; * uint16 epoch; // DTLS only * uint48 sequence_number; // DTLS only * uint16 length; * * Return 0 if header looks sane (and, for DTLS, the record is expected) * MBEDTLS_ERR_SSL_INVALID_RECORD if the header looks bad, * MBEDTLS_ERR_SSL_UNEXPECTED_RECORD (DTLS only) if sane but unexpected. * * With DTLS, mbedtls_ssl_read_record() will: * 1. proceed with the record if this function returns 0 * 2. drop only the current record if this function returns UNEXPECTED_RECORD * 3. return CLIENT_RECONNECT if this function return that value * 4. drop the whole datagram if this function returns anything else. * Point 2 is needed when the peer is resending, and we have already received * the first record from a datagram but are still waiting for the others. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_parse_record_header(mbedtls_ssl_context const *ssl, unsigned char *buf, size_t len, mbedtls_record *rec) { mbedtls_ssl_protocol_version tls_version; size_t const rec_hdr_type_offset = 0; size_t const rec_hdr_type_len = 1; size_t const rec_hdr_version_offset = rec_hdr_type_offset + rec_hdr_type_len; size_t const rec_hdr_version_len = 2; size_t const rec_hdr_ctr_len = 8; #if defined(MBEDTLS_SSL_PROTO_DTLS) uint32_t rec_epoch; size_t const rec_hdr_ctr_offset = rec_hdr_version_offset + rec_hdr_version_len; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) size_t const rec_hdr_cid_offset = rec_hdr_ctr_offset + rec_hdr_ctr_len; size_t rec_hdr_cid_len = 0; #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ #endif /* MBEDTLS_SSL_PROTO_DTLS */ size_t rec_hdr_len_offset; /* To be determined */ size_t const rec_hdr_len_len = 2; /* * Check minimum lengths for record header. */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { rec_hdr_len_offset = rec_hdr_ctr_offset + rec_hdr_ctr_len; } else #endif /* MBEDTLS_SSL_PROTO_DTLS */ { rec_hdr_len_offset = rec_hdr_version_offset + rec_hdr_version_len; } if (len < rec_hdr_len_offset + rec_hdr_len_len) { MBEDTLS_SSL_DEBUG_MSG(1, ( "datagram of length %u too small to hold DTLS record header of length %u", (unsigned) len, (unsigned) (rec_hdr_len_len + rec_hdr_len_len))); return MBEDTLS_ERR_SSL_INVALID_RECORD; } /* * Parse and validate record content type */ rec->type = buf[rec_hdr_type_offset]; /* Check record content type */ #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) rec->cid_len = 0; if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && ssl->conf->cid_len != 0 && rec->type == MBEDTLS_SSL_MSG_CID) { /* Shift pointers to account for record header including CID * struct { * ContentType outer_type = tls12_cid; * ProtocolVersion version; * uint16 epoch; * uint48 sequence_number; * opaque cid[cid_length]; // Additional field compared to * // default DTLS record format * uint16 length; * opaque enc_content[DTLSCiphertext.length]; * } DTLSCiphertext; */ /* So far, we only support static CID lengths * fixed in the configuration. */ rec_hdr_cid_len = ssl->conf->cid_len; rec_hdr_len_offset += rec_hdr_cid_len; if (len < rec_hdr_len_offset + rec_hdr_len_len) { MBEDTLS_SSL_DEBUG_MSG(1, ( "datagram of length %u too small to hold DTLS record header including CID, length %u", (unsigned) len, (unsigned) (rec_hdr_len_offset + rec_hdr_len_len))); return MBEDTLS_ERR_SSL_INVALID_RECORD; } /* configured CID len is guaranteed at most 255, see * MBEDTLS_SSL_CID_OUT_LEN_MAX in check_config.h */ rec->cid_len = (uint8_t) rec_hdr_cid_len; memcpy(rec->cid, buf + rec_hdr_cid_offset, rec_hdr_cid_len); } else #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ { if (ssl_check_record_type(rec->type)) { MBEDTLS_SSL_DEBUG_MSG(1, ("unknown record type %u", (unsigned) rec->type)); return MBEDTLS_ERR_SSL_INVALID_RECORD; } } /* * Parse and validate record version */ rec->ver[0] = buf[rec_hdr_version_offset + 0]; rec->ver[1] = buf[rec_hdr_version_offset + 1]; tls_version = (mbedtls_ssl_protocol_version) mbedtls_ssl_read_version( buf + rec_hdr_version_offset, ssl->conf->transport); if (tls_version > ssl->conf->max_tls_version) { MBEDTLS_SSL_DEBUG_MSG(1, ("TLS version mismatch: got %u, expected max %u", (unsigned) tls_version, (unsigned) ssl->conf->max_tls_version)); return MBEDTLS_ERR_SSL_INVALID_RECORD; } /* * Parse/Copy record sequence number. */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { /* Copy explicit record sequence number from input buffer. */ memcpy(&rec->ctr[0], buf + rec_hdr_ctr_offset, rec_hdr_ctr_len); } else #endif /* MBEDTLS_SSL_PROTO_DTLS */ { /* Copy implicit record sequence number from SSL context structure. */ memcpy(&rec->ctr[0], ssl->in_ctr, rec_hdr_ctr_len); } /* * Parse record length. */ rec->data_offset = rec_hdr_len_offset + rec_hdr_len_len; rec->data_len = ((size_t) buf[rec_hdr_len_offset + 0] << 8) | ((size_t) buf[rec_hdr_len_offset + 1] << 0); MBEDTLS_SSL_DEBUG_BUF(4, "input record header", buf, rec->data_offset); MBEDTLS_SSL_DEBUG_MSG(3, ("input record: msgtype = %u, " "version = [0x%x], msglen = %" MBEDTLS_PRINTF_SIZET, rec->type, (unsigned) tls_version, rec->data_len)); rec->buf = buf; rec->buf_len = rec->data_offset + rec->data_len; if (rec->data_len == 0) { return MBEDTLS_ERR_SSL_INVALID_RECORD; } /* * DTLS-related tests. * Check epoch before checking length constraint because * the latter varies with the epoch. E.g., if a ChangeCipherSpec * message gets duplicated before the corresponding Finished message, * the second ChangeCipherSpec should be discarded because it belongs * to an old epoch, but not because its length is shorter than * the minimum record length for packets using the new record transform. * Note that these two kinds of failures are handled differently, * as an unexpected record is silently skipped but an invalid * record leads to the entire datagram being dropped. */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { rec_epoch = (rec->ctr[0] << 8) | rec->ctr[1]; /* Check that the datagram is large enough to contain a record * of the advertised length. */ if (len < rec->data_offset + rec->data_len) { MBEDTLS_SSL_DEBUG_MSG(1, ( "Datagram of length %u too small to contain record of advertised length %u.", (unsigned) len, (unsigned) (rec->data_offset + rec->data_len))); return MBEDTLS_ERR_SSL_INVALID_RECORD; } /* Records from other, non-matching epochs are silently discarded. * (The case of same-port Client reconnects must be considered in * the caller). */ if (rec_epoch != ssl->in_epoch) { MBEDTLS_SSL_DEBUG_MSG(1, ("record from another epoch: " "expected %u, received %lu", ssl->in_epoch, (unsigned long) rec_epoch)); /* Records from the next epoch are considered for buffering * (concretely: early Finished messages). */ if (rec_epoch == (unsigned) ssl->in_epoch + 1) { MBEDTLS_SSL_DEBUG_MSG(2, ("Consider record for buffering")); return MBEDTLS_ERR_SSL_EARLY_MESSAGE; } return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; } #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) /* For records from the correct epoch, check whether their * sequence number has been seen before. */ else if (mbedtls_ssl_dtls_record_replay_check((mbedtls_ssl_context *) ssl, &rec->ctr[0]) != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("replayed record")); return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; } #endif } #endif /* MBEDTLS_SSL_PROTO_DTLS */ return 0; } #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_check_client_reconnect(mbedtls_ssl_context *ssl) { unsigned int rec_epoch = (ssl->in_ctr[0] << 8) | ssl->in_ctr[1]; /* * Check for an epoch 0 ClientHello. We can't use in_msg here to * access the first byte of record content (handshake type), as we * have an active transform (possibly iv_len != 0), so use the * fact that the record header len is 13 instead. */ if (rec_epoch == 0 && ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER && mbedtls_ssl_is_handshake_over(ssl) == 1 && ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && ssl->in_left > 13 && ssl->in_buf[13] == MBEDTLS_SSL_HS_CLIENT_HELLO) { MBEDTLS_SSL_DEBUG_MSG(1, ("possible client reconnect " "from the same port")); return ssl_handle_possible_reconnect(ssl); } return 0; } #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */ /* * If applicable, decrypt record content */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_prepare_record_content(mbedtls_ssl_context *ssl, mbedtls_record *rec) { int ret, done = 0; MBEDTLS_SSL_DEBUG_BUF(4, "input record from network", rec->buf, rec->buf_len); /* * In TLS 1.3, always treat ChangeCipherSpec records * as unencrypted. The only thing we do with them is * check the length and content and ignore them. */ #if defined(MBEDTLS_SSL_PROTO_TLS1_3) if (ssl->transform_in != NULL && ssl->transform_in->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { if (rec->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { done = 1; } } #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ if (!done && ssl->transform_in != NULL) { unsigned char const old_msg_type = rec->type; if ((ret = mbedtls_ssl_decrypt_buf(ssl, ssl->transform_in, rec)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_decrypt_buf", ret); #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID && ssl->conf->ignore_unexpected_cid == MBEDTLS_SSL_UNEXPECTED_CID_IGNORE) { MBEDTLS_SSL_DEBUG_MSG(3, ("ignoring unexpected CID")); ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; } #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ return ret; } if (old_msg_type != rec->type) { MBEDTLS_SSL_DEBUG_MSG(4, ("record type after decrypt (before %d): %d", old_msg_type, rec->type)); } MBEDTLS_SSL_DEBUG_BUF(4, "input payload after decrypt", rec->buf + rec->data_offset, rec->data_len); #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) /* We have already checked the record content type * in ssl_parse_record_header(), failing or silently * dropping the record in the case of an unknown type. * * Since with the use of CIDs, the record content type * might change during decryption, re-check the record * content type, but treat a failure as fatal this time. */ if (ssl_check_record_type(rec->type)) { MBEDTLS_SSL_DEBUG_MSG(1, ("unknown record type")); return MBEDTLS_ERR_SSL_INVALID_RECORD; } #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ if (rec->data_len == 0) { #if defined(MBEDTLS_SSL_PROTO_TLS1_2) if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_2 && rec->type != MBEDTLS_SSL_MSG_APPLICATION_DATA) { /* TLS v1.2 explicitly disallows zero-length messages which are not application data */ MBEDTLS_SSL_DEBUG_MSG(1, ("invalid zero-length message type: %d", ssl->in_msgtype)); return MBEDTLS_ERR_SSL_INVALID_RECORD; } #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ ssl->nb_zero++; /* * Three or more empty messages may be a DoS attack * (excessive CPU consumption). */ if (ssl->nb_zero > 3) { MBEDTLS_SSL_DEBUG_MSG(1, ("received four consecutive empty " "messages, possible DoS attack")); /* Treat the records as if they were not properly authenticated, * thereby failing the connection if we see more than allowed * by the configured bad MAC threshold. */ return MBEDTLS_ERR_SSL_INVALID_MAC; } } else { ssl->nb_zero = 0; } #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { ; /* in_ctr read from peer, not maintained internally */ } else #endif { unsigned i; for (i = MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; i > mbedtls_ssl_ep_len(ssl); i--) { if (++ssl->in_ctr[i - 1] != 0) { break; } } /* The loop goes to its end iff the counter is wrapping */ if (i == mbedtls_ssl_ep_len(ssl)) { MBEDTLS_SSL_DEBUG_MSG(1, ("incoming message counter would wrap")); return MBEDTLS_ERR_SSL_COUNTER_WRAPPING; } } } #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { mbedtls_ssl_dtls_replay_update(ssl); } #endif /* Check actual (decrypted) record content length against * configured maximum. */ if (rec->data_len > MBEDTLS_SSL_IN_CONTENT_LEN) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad message length")); return MBEDTLS_ERR_SSL_INVALID_RECORD; } return 0; } /* * Read a record. * * Silently ignore non-fatal alert (and for DTLS, invalid records as well, * RFC 6347 4.1.2.7) and continue reading until a valid record is found. * */ /* Helper functions for mbedtls_ssl_read_record(). */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_consume_current_message(mbedtls_ssl_context *ssl); MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_get_next_record(mbedtls_ssl_context *ssl); MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_record_is_in_progress(mbedtls_ssl_context *ssl); int mbedtls_ssl_read_record(mbedtls_ssl_context *ssl, unsigned update_hs_digest) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG(2, ("=> read record")); if (ssl->keep_current_message == 0) { do { ret = ssl_consume_current_message(ssl); if (ret != 0) { return ret; } if (ssl_record_is_in_progress(ssl) == 0) { int dtls_have_buffered = 0; #if defined(MBEDTLS_SSL_PROTO_DTLS) /* We only check for buffered messages if the * current datagram is fully consumed. */ if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && ssl_next_record_is_in_datagram(ssl) == 0) { if (ssl_load_buffered_message(ssl) == 0) { dtls_have_buffered = 1; } } #endif /* MBEDTLS_SSL_PROTO_DTLS */ if (dtls_have_buffered == 0) { ret = ssl_get_next_record(ssl); if (ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING) { continue; } if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, ("ssl_get_next_record"), ret); return ret; } } } ret = mbedtls_ssl_handle_message_type(ssl); #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) { /* Buffer future message */ ret = ssl_buffer_message(ssl); if (ret != 0) { return ret; } ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; } #endif /* MBEDTLS_SSL_PROTO_DTLS */ } while (MBEDTLS_ERR_SSL_NON_FATAL == ret || MBEDTLS_ERR_SSL_CONTINUE_PROCESSING == ret); if (0 != ret) { MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_handle_message_type"), ret); return ret; } if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE && update_hs_digest == 1) { ret = mbedtls_ssl_update_handshake_status(ssl); if (0 != ret) { MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_update_handshake_status"), ret); return ret; } } } else { MBEDTLS_SSL_DEBUG_MSG(2, ("reuse previously read message")); ssl->keep_current_message = 0; } MBEDTLS_SSL_DEBUG_MSG(2, ("<= read record")); return 0; } #if defined(MBEDTLS_SSL_PROTO_DTLS) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_next_record_is_in_datagram(mbedtls_ssl_context *ssl) { if (ssl->in_left > ssl->next_record_offset) { return 1; } return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_load_buffered_message(mbedtls_ssl_context *ssl) { mbedtls_ssl_handshake_params * const hs = ssl->handshake; mbedtls_ssl_hs_buffer *hs_buf; int ret = 0; if (hs == NULL) { return -1; } MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_load_buffered_message")); if (ssl->state == MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC || ssl->state == MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC) { /* Check if we have seen a ChangeCipherSpec before. * If yes, synthesize a CCS record. */ if (!hs->buffering.seen_ccs) { MBEDTLS_SSL_DEBUG_MSG(2, ("CCS not seen in the current flight")); ret = -1; goto exit; } MBEDTLS_SSL_DEBUG_MSG(2, ("Injecting buffered CCS message")); ssl->in_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC; ssl->in_msglen = 1; ssl->in_msg[0] = 1; /* As long as they are equal, the exact value doesn't matter. */ ssl->in_left = 0; ssl->next_record_offset = 0; hs->buffering.seen_ccs = 0; goto exit; } #if defined(MBEDTLS_DEBUG_C) /* Debug only */ { unsigned offset; for (offset = 1; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++) { hs_buf = &hs->buffering.hs[offset]; if (hs_buf->is_valid == 1) { MBEDTLS_SSL_DEBUG_MSG(2, ("Future message with sequence number %u %s buffered.", hs->in_msg_seq + offset, hs_buf->is_complete ? "fully" : "partially")); } } } #endif /* MBEDTLS_DEBUG_C */ /* Check if we have buffered and/or fully reassembled the * next handshake message. */ hs_buf = &hs->buffering.hs[0]; if ((hs_buf->is_valid == 1) && (hs_buf->is_complete == 1)) { /* Synthesize a record containing the buffered HS message. */ size_t msg_len = (hs_buf->data[1] << 16) | (hs_buf->data[2] << 8) | hs_buf->data[3]; /* Double-check that we haven't accidentally buffered * a message that doesn't fit into the input buffer. */ if (msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } MBEDTLS_SSL_DEBUG_MSG(2, ("Next handshake message has been buffered - load")); MBEDTLS_SSL_DEBUG_BUF(3, "Buffered handshake message (incl. header)", hs_buf->data, msg_len + 12); ssl->in_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE; ssl->in_hslen = msg_len + 12; ssl->in_msglen = msg_len + 12; memcpy(ssl->in_msg, hs_buf->data, ssl->in_hslen); ret = 0; goto exit; } else { MBEDTLS_SSL_DEBUG_MSG(2, ("Next handshake message %u not or only partially bufffered", hs->in_msg_seq)); } ret = -1; exit: MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_load_buffered_message")); return ret; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_buffer_make_space(mbedtls_ssl_context *ssl, size_t desired) { int offset; mbedtls_ssl_handshake_params * const hs = ssl->handshake; MBEDTLS_SSL_DEBUG_MSG(2, ("Attempt to free buffered messages to have %u bytes available", (unsigned) desired)); /* Get rid of future records epoch first, if such exist. */ ssl_free_buffered_record(ssl); /* Check if we have enough space available now. */ if (desired <= (MBEDTLS_SSL_DTLS_MAX_BUFFERING - hs->buffering.total_bytes_buffered)) { MBEDTLS_SSL_DEBUG_MSG(2, ("Enough space available after freeing future epoch record")); return 0; } /* We don't have enough space to buffer the next expected handshake * message. Remove buffers used for future messages to gain space, * starting with the most distant one. */ for (offset = MBEDTLS_SSL_MAX_BUFFERED_HS - 1; offset >= 0; offset--) { MBEDTLS_SSL_DEBUG_MSG(2, ( "Free buffering slot %d to make space for reassembly of next handshake message", offset)); ssl_buffering_free_slot(ssl, (uint8_t) offset); /* Check if we have enough space available now. */ if (desired <= (MBEDTLS_SSL_DTLS_MAX_BUFFERING - hs->buffering.total_bytes_buffered)) { MBEDTLS_SSL_DEBUG_MSG(2, ("Enough space available after freeing buffered HS messages")); return 0; } } return -1; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_buffer_message(mbedtls_ssl_context *ssl) { int ret = 0; mbedtls_ssl_handshake_params * const hs = ssl->handshake; if (hs == NULL) { return 0; } MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_buffer_message")); switch (ssl->in_msgtype) { case MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC: MBEDTLS_SSL_DEBUG_MSG(2, ("Remember CCS message")); hs->buffering.seen_ccs = 1; break; case MBEDTLS_SSL_MSG_HANDSHAKE: { unsigned recv_msg_seq_offset; unsigned recv_msg_seq = (ssl->in_msg[4] << 8) | ssl->in_msg[5]; mbedtls_ssl_hs_buffer *hs_buf; size_t msg_len = ssl->in_hslen - 12; /* We should never receive an old handshake * message - double-check nonetheless. */ if (recv_msg_seq < ssl->handshake->in_msg_seq) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } recv_msg_seq_offset = recv_msg_seq - ssl->handshake->in_msg_seq; if (recv_msg_seq_offset >= MBEDTLS_SSL_MAX_BUFFERED_HS) { /* Silently ignore -- message too far in the future */ MBEDTLS_SSL_DEBUG_MSG(2, ("Ignore future HS message with sequence number %u, " "buffering window %u - %u", recv_msg_seq, ssl->handshake->in_msg_seq, ssl->handshake->in_msg_seq + MBEDTLS_SSL_MAX_BUFFERED_HS - 1)); goto exit; } MBEDTLS_SSL_DEBUG_MSG(2, ("Buffering HS message with sequence number %u, offset %u ", recv_msg_seq, recv_msg_seq_offset)); hs_buf = &hs->buffering.hs[recv_msg_seq_offset]; /* Check if the buffering for this seq nr has already commenced. */ if (!hs_buf->is_valid) { size_t reassembly_buf_sz; hs_buf->is_fragmented = (ssl_hs_is_proper_fragment(ssl) == 1); /* We copy the message back into the input buffer * after reassembly, so check that it's not too large. * This is an implementation-specific limitation * and not one from the standard, hence it is not * checked in ssl_check_hs_header(). */ if (msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN) { /* Ignore message */ goto exit; } /* Check if we have enough space to buffer the message. */ if (hs->buffering.total_bytes_buffered > MBEDTLS_SSL_DTLS_MAX_BUFFERING) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } reassembly_buf_sz = ssl_get_reassembly_buffer_size(msg_len, hs_buf->is_fragmented); if (reassembly_buf_sz > (MBEDTLS_SSL_DTLS_MAX_BUFFERING - hs->buffering.total_bytes_buffered)) { if (recv_msg_seq_offset > 0) { /* If we can't buffer a future message because * of space limitations -- ignore. */ MBEDTLS_SSL_DEBUG_MSG(2, ("Buffering of future message of size %" MBEDTLS_PRINTF_SIZET " would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET " (already %" MBEDTLS_PRINTF_SIZET " bytes buffered) -- ignore\n", msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING, hs->buffering.total_bytes_buffered)); goto exit; } else { MBEDTLS_SSL_DEBUG_MSG(2, ("Buffering of future message of size %" MBEDTLS_PRINTF_SIZET " would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET " (already %" MBEDTLS_PRINTF_SIZET " bytes buffered) -- attempt to make space by freeing buffered future messages\n", msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING, hs->buffering.total_bytes_buffered)); } if (ssl_buffer_make_space(ssl, reassembly_buf_sz) != 0) { MBEDTLS_SSL_DEBUG_MSG(2, ("Reassembly of next message of size %" MBEDTLS_PRINTF_SIZET " (%" MBEDTLS_PRINTF_SIZET " with bitmap) would exceed" " the compile-time limit %" MBEDTLS_PRINTF_SIZET " (already %" MBEDTLS_PRINTF_SIZET " bytes buffered) -- fail\n", msg_len, reassembly_buf_sz, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING, hs->buffering.total_bytes_buffered)); ret = MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL; goto exit; } } MBEDTLS_SSL_DEBUG_MSG(2, ("initialize reassembly, total length = %" MBEDTLS_PRINTF_SIZET, msg_len)); hs_buf->data = mbedtls_calloc(1, reassembly_buf_sz); if (hs_buf->data == NULL) { ret = MBEDTLS_ERR_SSL_ALLOC_FAILED; goto exit; } hs_buf->data_len = reassembly_buf_sz; /* Prepare final header: copy msg_type, length and message_seq, * then add standardised fragment_offset and fragment_length */ memcpy(hs_buf->data, ssl->in_msg, 6); memset(hs_buf->data + 6, 0, 3); memcpy(hs_buf->data + 9, hs_buf->data + 1, 3); hs_buf->is_valid = 1; hs->buffering.total_bytes_buffered += reassembly_buf_sz; } else { /* Make sure msg_type and length are consistent */ if (memcmp(hs_buf->data, ssl->in_msg, 4) != 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("Fragment header mismatch - ignore")); /* Ignore */ goto exit; } } if (!hs_buf->is_complete) { size_t frag_len, frag_off; unsigned char * const msg = hs_buf->data + 12; /* * Check and copy current fragment */ /* Validation of header fields already done in * mbedtls_ssl_prepare_handshake_record(). */ frag_off = ssl_get_hs_frag_off(ssl); frag_len = ssl_get_hs_frag_len(ssl); MBEDTLS_SSL_DEBUG_MSG(2, ("adding fragment, offset = %" MBEDTLS_PRINTF_SIZET ", length = %" MBEDTLS_PRINTF_SIZET, frag_off, frag_len)); memcpy(msg + frag_off, ssl->in_msg + 12, frag_len); if (hs_buf->is_fragmented) { unsigned char * const bitmask = msg + msg_len; ssl_bitmask_set(bitmask, frag_off, frag_len); hs_buf->is_complete = (ssl_bitmask_check(bitmask, msg_len) == 0); } else { hs_buf->is_complete = 1; } MBEDTLS_SSL_DEBUG_MSG(2, ("message %scomplete", hs_buf->is_complete ? "" : "not yet ")); } break; } default: /* We don't buffer other types of messages. */ break; } exit: MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_buffer_message")); return ret; } #endif /* MBEDTLS_SSL_PROTO_DTLS */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_consume_current_message(mbedtls_ssl_context *ssl) { /* * Consume last content-layer message and potentially * update in_msglen which keeps track of the contents' * consumption state. * * (1) Handshake messages: * Remove last handshake message, move content * and adapt in_msglen. * * (2) Alert messages: * Consume whole record content, in_msglen = 0. * * (3) Change cipher spec: * Consume whole record content, in_msglen = 0. * * (4) Application data: * Don't do anything - the record layer provides * the application data as a stream transport * and consumes through mbedtls_ssl_read only. * */ /* Case (1): Handshake messages */ if (ssl->in_hslen != 0) { /* Hard assertion to be sure that no application data * is in flight, as corrupting ssl->in_msglen during * ssl->in_offt != NULL is fatal. */ if (ssl->in_offt != NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* * Get next Handshake message in the current record */ /* Notes: * (1) in_hslen is not necessarily the size of the * current handshake content: If DTLS handshake * fragmentation is used, that's the fragment * size instead. Using the total handshake message * size here is faulty and should be changed at * some point. * (2) While it doesn't seem to cause problems, one * has to be very careful not to assume that in_hslen * is always <= in_msglen in a sensible communication. * Again, it's wrong for DTLS handshake fragmentation. * The following check is therefore mandatory, and * should not be treated as a silently corrected assertion. * Additionally, ssl->in_hslen might be arbitrarily out of * bounds after handling a DTLS message with an unexpected * sequence number, see mbedtls_ssl_prepare_handshake_record. */ if (ssl->in_hslen < ssl->in_msglen) { ssl->in_msglen -= ssl->in_hslen; memmove(ssl->in_msg, ssl->in_msg + ssl->in_hslen, ssl->in_msglen); MBEDTLS_SSL_DEBUG_BUF(4, "remaining content in record", ssl->in_msg, ssl->in_msglen); } else { ssl->in_msglen = 0; } ssl->in_hslen = 0; } /* Case (4): Application data */ else if (ssl->in_offt != NULL) { return 0; } /* Everything else (CCS & Alerts) */ else { ssl->in_msglen = 0; } return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_record_is_in_progress(mbedtls_ssl_context *ssl) { if (ssl->in_msglen > 0) { return 1; } return 0; } #if defined(MBEDTLS_SSL_PROTO_DTLS) static void ssl_free_buffered_record(mbedtls_ssl_context *ssl) { mbedtls_ssl_handshake_params * const hs = ssl->handshake; if (hs == NULL) { return; } if (hs->buffering.future_record.data != NULL) { hs->buffering.total_bytes_buffered -= hs->buffering.future_record.len; mbedtls_free(hs->buffering.future_record.data); hs->buffering.future_record.data = NULL; } } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_load_buffered_record(mbedtls_ssl_context *ssl) { mbedtls_ssl_handshake_params * const hs = ssl->handshake; unsigned char *rec; size_t rec_len; unsigned rec_epoch; #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) size_t in_buf_len = ssl->in_buf_len; #else size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN; #endif if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) { return 0; } if (hs == NULL) { return 0; } rec = hs->buffering.future_record.data; rec_len = hs->buffering.future_record.len; rec_epoch = hs->buffering.future_record.epoch; if (rec == NULL) { return 0; } /* Only consider loading future records if the * input buffer is empty. */ if (ssl_next_record_is_in_datagram(ssl) == 1) { return 0; } MBEDTLS_SSL_DEBUG_MSG(2, ("=> ssl_load_buffered_record")); if (rec_epoch != ssl->in_epoch) { MBEDTLS_SSL_DEBUG_MSG(2, ("Buffered record not from current epoch.")); goto exit; } MBEDTLS_SSL_DEBUG_MSG(2, ("Found buffered record from current epoch - load")); /* Double-check that the record is not too large */ if (rec_len > in_buf_len - (size_t) (ssl->in_hdr - ssl->in_buf)) { MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } memcpy(ssl->in_hdr, rec, rec_len); ssl->in_left = rec_len; ssl->next_record_offset = 0; ssl_free_buffered_record(ssl); exit: MBEDTLS_SSL_DEBUG_MSG(2, ("<= ssl_load_buffered_record")); return 0; } MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_buffer_future_record(mbedtls_ssl_context *ssl, mbedtls_record const *rec) { mbedtls_ssl_handshake_params * const hs = ssl->handshake; /* Don't buffer future records outside handshakes. */ if (hs == NULL) { return 0; } /* Only buffer handshake records (we are only interested * in Finished messages). */ if (rec->type != MBEDTLS_SSL_MSG_HANDSHAKE) { return 0; } /* Don't buffer more than one future epoch record. */ if (hs->buffering.future_record.data != NULL) { return 0; } /* Don't buffer record if there's not enough buffering space remaining. */ if (rec->buf_len > (MBEDTLS_SSL_DTLS_MAX_BUFFERING - hs->buffering.total_bytes_buffered)) { MBEDTLS_SSL_DEBUG_MSG(2, ("Buffering of future epoch record of size %" MBEDTLS_PRINTF_SIZET " would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET " (already %" MBEDTLS_PRINTF_SIZET " bytes buffered) -- ignore\n", rec->buf_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING, hs->buffering.total_bytes_buffered)); return 0; } /* Buffer record */ MBEDTLS_SSL_DEBUG_MSG(2, ("Buffer record from epoch %u", ssl->in_epoch + 1U)); MBEDTLS_SSL_DEBUG_BUF(3, "Buffered record", rec->buf, rec->buf_len); /* ssl_parse_record_header() only considers records * of the next epoch as candidates for buffering. */ hs->buffering.future_record.epoch = ssl->in_epoch + 1; hs->buffering.future_record.len = rec->buf_len; hs->buffering.future_record.data = mbedtls_calloc(1, hs->buffering.future_record.len); if (hs->buffering.future_record.data == NULL) { /* If we run out of RAM trying to buffer a * record from the next epoch, just ignore. */ return 0; } memcpy(hs->buffering.future_record.data, rec->buf, rec->buf_len); hs->buffering.total_bytes_buffered += rec->buf_len; return 0; } #endif /* MBEDTLS_SSL_PROTO_DTLS */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_get_next_record(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_record rec; #if defined(MBEDTLS_SSL_PROTO_DTLS) /* We might have buffered a future record; if so, * and if the epoch matches now, load it. * On success, this call will set ssl->in_left to * the length of the buffered record, so that * the calls to ssl_fetch_input() below will * essentially be no-ops. */ ret = ssl_load_buffered_record(ssl); if (ret != 0) { return ret; } #endif /* MBEDTLS_SSL_PROTO_DTLS */ /* Ensure that we have enough space available for the default form * of TLS / DTLS record headers (5 Bytes for TLS, 13 Bytes for DTLS, * with no space for CIDs counted in). */ ret = mbedtls_ssl_fetch_input(ssl, mbedtls_ssl_in_hdr_len(ssl)); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_fetch_input", ret); return ret; } ret = ssl_parse_record_header(ssl, ssl->in_hdr, ssl->in_left, &rec); if (ret != 0) { #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { if (ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE) { ret = ssl_buffer_future_record(ssl, &rec); if (ret != 0) { return ret; } /* Fall through to handling of unexpected records */ ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; } if (ret == MBEDTLS_ERR_SSL_UNEXPECTED_RECORD) { #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C) /* Reset in pointers to default state for TLS/DTLS records, * assuming no CID and no offset between record content and * record plaintext. */ mbedtls_ssl_update_in_pointers(ssl); /* Setup internal message pointers from record structure. */ ssl->in_msgtype = rec.type; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) ssl->in_len = ssl->in_cid + rec.cid_len; #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ ssl->in_iv = ssl->in_msg = ssl->in_len + 2; ssl->in_msglen = rec.data_len; ret = ssl_check_client_reconnect(ssl); MBEDTLS_SSL_DEBUG_RET(2, "ssl_check_client_reconnect", ret); if (ret != 0) { return ret; } #endif /* Skip unexpected record (but not whole datagram) */ ssl->next_record_offset = rec.buf_len; MBEDTLS_SSL_DEBUG_MSG(1, ("discarding unexpected record " "(header)")); } else { /* Skip invalid record and the rest of the datagram */ ssl->next_record_offset = 0; ssl->in_left = 0; MBEDTLS_SSL_DEBUG_MSG(1, ("discarding invalid record " "(header)")); } /* Get next record */ return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; } else #endif { return ret; } } #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { /* Remember offset of next record within datagram. */ ssl->next_record_offset = rec.buf_len; if (ssl->next_record_offset < ssl->in_left) { MBEDTLS_SSL_DEBUG_MSG(3, ("more than one record within datagram")); } } else #endif { /* * Fetch record contents from underlying transport. */ ret = mbedtls_ssl_fetch_input(ssl, rec.buf_len); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_fetch_input", ret); return ret; } ssl->in_left = 0; } /* * Decrypt record contents. */ if ((ret = ssl_prepare_record_content(ssl, &rec)) != 0) { #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { /* Silently discard invalid records */ if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) { /* Except when waiting for Finished as a bad mac here * probably means something went wrong in the handshake * (eg wrong psk used, mitm downgrade attempt, etc.) */ if (ssl->state == MBEDTLS_SSL_CLIENT_FINISHED || ssl->state == MBEDTLS_SSL_SERVER_FINISHED) { #if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES) if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) { mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC); } #endif return ret; } if (ssl->conf->badmac_limit != 0 && ++ssl->badmac_seen >= ssl->conf->badmac_limit) { MBEDTLS_SSL_DEBUG_MSG(1, ("too many records with bad MAC")); return MBEDTLS_ERR_SSL_INVALID_MAC; } /* As above, invalid records cause * dismissal of the whole datagram. */ ssl->next_record_offset = 0; ssl->in_left = 0; MBEDTLS_SSL_DEBUG_MSG(1, ("discarding invalid record (mac)")); return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; } return ret; } else #endif { /* Error out (and send alert) on invalid records */ #if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES) if (ret == MBEDTLS_ERR_SSL_INVALID_MAC) { mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC); } #endif return ret; } } /* Reset in pointers to default state for TLS/DTLS records, * assuming no CID and no offset between record content and * record plaintext. */ mbedtls_ssl_update_in_pointers(ssl); #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) ssl->in_len = ssl->in_cid + rec.cid_len; #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ ssl->in_iv = ssl->in_len + 2; /* The record content type may change during decryption, * so re-read it. */ ssl->in_msgtype = rec.type; /* Also update the input buffer, because unfortunately * the server-side ssl_parse_client_hello() reparses the * record header when receiving a ClientHello initiating * a renegotiation. */ ssl->in_hdr[0] = rec.type; ssl->in_msg = rec.buf + rec.data_offset; ssl->in_msglen = rec.data_len; MBEDTLS_PUT_UINT16_BE(rec.data_len, ssl->in_len, 0); return 0; } int mbedtls_ssl_handle_message_type(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; /* * Handle particular types of records */ if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) { if ((ret = mbedtls_ssl_prepare_handshake_record(ssl)) != 0) { return ret; } } if (ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { if (ssl->in_msglen != 1) { MBEDTLS_SSL_DEBUG_MSG(1, ("invalid CCS message, len: %" MBEDTLS_PRINTF_SIZET, ssl->in_msglen)); return MBEDTLS_ERR_SSL_INVALID_RECORD; } if (ssl->in_msg[0] != 1) { MBEDTLS_SSL_DEBUG_MSG(1, ("invalid CCS message, content: %02x", ssl->in_msg[0])); return MBEDTLS_ERR_SSL_INVALID_RECORD; } #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC && ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC) { if (ssl->handshake == NULL) { MBEDTLS_SSL_DEBUG_MSG(1, ("dropping ChangeCipherSpec outside handshake")); return MBEDTLS_ERR_SSL_UNEXPECTED_RECORD; } MBEDTLS_SSL_DEBUG_MSG(1, ("received out-of-order ChangeCipherSpec - remember")); return MBEDTLS_ERR_SSL_EARLY_MESSAGE; } #endif #if defined(MBEDTLS_SSL_PROTO_TLS1_3) if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { #if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE) MBEDTLS_SSL_DEBUG_MSG(1, ("Ignore ChangeCipherSpec in TLS 1.3 compatibility mode")); return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING; #else MBEDTLS_SSL_DEBUG_MSG(1, ("ChangeCipherSpec invalid in TLS 1.3 without compatibility mode")); return MBEDTLS_ERR_SSL_INVALID_RECORD; #endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */ } #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ } if (ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT) { if (ssl->in_msglen != 2) { /* Note: Standard allows for more than one 2 byte alert to be packed in a single message, but Mbed TLS doesn't currently support this. */ MBEDTLS_SSL_DEBUG_MSG(1, ("invalid alert message, len: %" MBEDTLS_PRINTF_SIZET, ssl->in_msglen)); return MBEDTLS_ERR_SSL_INVALID_RECORD; } MBEDTLS_SSL_DEBUG_MSG(2, ("got an alert message, type: [%u:%u]", ssl->in_msg[0], ssl->in_msg[1])); /* * Ignore non-fatal alerts, except close_notify and no_renegotiation */ if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL) { MBEDTLS_SSL_DEBUG_MSG(1, ("is a fatal alert message (msg %d)", ssl->in_msg[1])); return MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE; } if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING && ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY) { MBEDTLS_SSL_DEBUG_MSG(2, ("is a close notify message")); return MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY; } #if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED) if (ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING && ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION) { MBEDTLS_SSL_DEBUG_MSG(2, ("is a no renegotiation alert")); /* Will be handled when trying to parse ServerHello */ return 0; } #endif /* Silently ignore: fetch new message */ return MBEDTLS_ERR_SSL_NON_FATAL; } #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { /* Drop unexpected ApplicationData records, * except at the beginning of renegotiations */ if (ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA && mbedtls_ssl_is_handshake_over(ssl) == 0 #if defined(MBEDTLS_SSL_RENEGOTIATION) && !(ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS && ssl->state == MBEDTLS_SSL_SERVER_HELLO) #endif ) { MBEDTLS_SSL_DEBUG_MSG(1, ("dropping unexpected ApplicationData")); return MBEDTLS_ERR_SSL_NON_FATAL; } if (ssl->handshake != NULL && mbedtls_ssl_is_handshake_over(ssl) == 1) { mbedtls_ssl_handshake_wrapup_free_hs_transform(ssl); } } #endif /* MBEDTLS_SSL_PROTO_DTLS */ return 0; } int mbedtls_ssl_send_fatal_handshake_failure(mbedtls_ssl_context *ssl) { return mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE); } int mbedtls_ssl_send_alert_message(mbedtls_ssl_context *ssl, unsigned char level, unsigned char message) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; if (ssl == NULL || ssl->conf == NULL) { return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } if (ssl->out_left != 0) { return mbedtls_ssl_flush_output(ssl); } MBEDTLS_SSL_DEBUG_MSG(2, ("=> send alert message")); MBEDTLS_SSL_DEBUG_MSG(3, ("send alert level=%u message=%u", level, message)); ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT; ssl->out_msglen = 2; ssl->out_msg[0] = level; ssl->out_msg[1] = message; if ((ret = mbedtls_ssl_write_record(ssl, SSL_FORCE_FLUSH)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret); return ret; } MBEDTLS_SSL_DEBUG_MSG(2, ("<= send alert message")); return 0; } int mbedtls_ssl_write_change_cipher_spec(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write change cipher spec")); ssl->out_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC; ssl->out_msglen = 1; ssl->out_msg[0] = 1; ssl->state++; if ((ret = mbedtls_ssl_write_handshake_msg(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_handshake_msg", ret); return ret; } MBEDTLS_SSL_DEBUG_MSG(2, ("<= write change cipher spec")); return 0; } int mbedtls_ssl_parse_change_cipher_spec(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse change cipher spec")); if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); return ret; } if (ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad change cipher spec message")); mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE); return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; } /* CCS records are only accepted if they have length 1 and content '1', * so we don't need to check this here. */ /* * Switch to our negotiated transform and session parameters for inbound * data. */ MBEDTLS_SSL_DEBUG_MSG(3, ("switching to new transform spec for inbound data")); #if defined(MBEDTLS_SSL_PROTO_TLS1_2) ssl->transform_in = ssl->transform_negotiate; #endif ssl->session_in = ssl->session_negotiate; #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) mbedtls_ssl_dtls_replay_reset(ssl); #endif /* Increment epoch */ if (++ssl->in_epoch == 0) { MBEDTLS_SSL_DEBUG_MSG(1, ("DTLS epoch would wrap")); /* This is highly unlikely to happen for legitimate reasons, so treat it as an attack and don't send an alert. */ return MBEDTLS_ERR_SSL_COUNTER_WRAPPING; } } else #endif /* MBEDTLS_SSL_PROTO_DTLS */ memset(ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN); mbedtls_ssl_update_in_pointers(ssl); ssl->state++; MBEDTLS_SSL_DEBUG_MSG(2, ("<= parse change cipher spec")); return 0; } /* Once ssl->out_hdr as the address of the beginning of the * next outgoing record is set, deduce the other pointers. * * Note: For TLS, we save the implicit record sequence number * (entering MAC computation) in the 8 bytes before ssl->out_hdr, * and the caller has to make sure there's space for this. */ static size_t ssl_transform_get_explicit_iv_len( mbedtls_ssl_transform const *transform) { return transform->ivlen - transform->fixed_ivlen; } void mbedtls_ssl_update_out_pointers(mbedtls_ssl_context *ssl, mbedtls_ssl_transform *transform) { #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { ssl->out_ctr = ssl->out_hdr + 3; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) ssl->out_cid = ssl->out_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; ssl->out_len = ssl->out_cid; if (transform != NULL) { ssl->out_len += transform->out_cid_len; } #else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ ssl->out_len = ssl->out_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ ssl->out_iv = ssl->out_len + 2; } else #endif { ssl->out_len = ssl->out_hdr + 3; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) ssl->out_cid = ssl->out_len; #endif ssl->out_iv = ssl->out_hdr + 5; } ssl->out_msg = ssl->out_iv; /* Adjust out_msg to make space for explicit IV, if used. */ if (transform != NULL) { ssl->out_msg += ssl_transform_get_explicit_iv_len(transform); } } /* Once ssl->in_hdr as the address of the beginning of the * next incoming record is set, deduce the other pointers. * * Note: For TLS, we save the implicit record sequence number * (entering MAC computation) in the 8 bytes before ssl->in_hdr, * and the caller has to make sure there's space for this. */ void mbedtls_ssl_update_in_pointers(mbedtls_ssl_context *ssl) { /* This function sets the pointers to match the case * of unprotected TLS/DTLS records, with both ssl->in_iv * and ssl->in_msg pointing to the beginning of the record * content. * * When decrypting a protected record, ssl->in_msg * will be shifted to point to the beginning of the * record plaintext. */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { /* This sets the header pointers to match records * without CID. When we receive a record containing * a CID, the fields are shifted accordingly in * ssl_parse_record_header(). */ ssl->in_ctr = ssl->in_hdr + 3; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) ssl->in_cid = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; ssl->in_len = ssl->in_cid; /* Default: no CID */ #else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ ssl->in_len = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ ssl->in_iv = ssl->in_len + 2; } else #endif { ssl->in_ctr = ssl->in_hdr - MBEDTLS_SSL_SEQUENCE_NUMBER_LEN; ssl->in_len = ssl->in_hdr + 3; #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) ssl->in_cid = ssl->in_len; #endif ssl->in_iv = ssl->in_hdr + 5; } /* This will be adjusted at record decryption time. */ ssl->in_msg = ssl->in_iv; } /* * Setup an SSL context */ void mbedtls_ssl_reset_in_out_pointers(mbedtls_ssl_context *ssl) { /* Set the incoming and outgoing record pointers. */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { ssl->out_hdr = ssl->out_buf; ssl->in_hdr = ssl->in_buf; } else #endif /* MBEDTLS_SSL_PROTO_DTLS */ { ssl->out_ctr = ssl->out_buf; ssl->out_hdr = ssl->out_buf + 8; ssl->in_hdr = ssl->in_buf + 8; } /* Derive other internal pointers. */ mbedtls_ssl_update_out_pointers(ssl, NULL /* no transform enabled */); mbedtls_ssl_update_in_pointers(ssl); } /* * SSL get accessors */ size_t mbedtls_ssl_get_bytes_avail(const mbedtls_ssl_context *ssl) { return ssl->in_offt == NULL ? 0 : ssl->in_msglen; } int mbedtls_ssl_check_pending(const mbedtls_ssl_context *ssl) { /* * Case A: We're currently holding back * a message for further processing. */ if (ssl->keep_current_message == 1) { MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: record held back for processing")); return 1; } /* * Case B: Further records are pending in the current datagram. */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && ssl->in_left > ssl->next_record_offset) { MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: more records within current datagram")); return 1; } #endif /* MBEDTLS_SSL_PROTO_DTLS */ /* * Case C: A handshake message is being processed. */ if (ssl->in_hslen > 0 && ssl->in_hslen < ssl->in_msglen) { MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: more handshake messages within current record")); return 1; } /* * Case D: An application data message is being processed */ if (ssl->in_offt != NULL) { MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: application data record is being processed")); return 1; } /* * In all other cases, the rest of the message can be dropped. * As in ssl_get_next_record, this needs to be adapted if * we implement support for multiple alerts in single records. */ MBEDTLS_SSL_DEBUG_MSG(3, ("ssl_check_pending: nothing pending")); return 0; } int mbedtls_ssl_get_record_expansion(const mbedtls_ssl_context *ssl) { size_t transform_expansion = 0; const mbedtls_ssl_transform *transform = ssl->transform_out; unsigned block_size; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_key_attributes_t attr = PSA_KEY_ATTRIBUTES_INIT; psa_key_type_t key_type; #endif /* MBEDTLS_USE_PSA_CRYPTO */ size_t out_hdr_len = mbedtls_ssl_out_hdr_len(ssl); if (transform == NULL) { return (int) out_hdr_len; } #if defined(MBEDTLS_USE_PSA_CRYPTO) if (transform->psa_alg == PSA_ALG_GCM || transform->psa_alg == PSA_ALG_CCM || transform->psa_alg == PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 8) || transform->psa_alg == PSA_ALG_CHACHA20_POLY1305 || transform->psa_alg == MBEDTLS_SSL_NULL_CIPHER) { transform_expansion = transform->minlen; } else if (transform->psa_alg == PSA_ALG_CBC_NO_PADDING) { (void) psa_get_key_attributes(transform->psa_key_enc, &attr); key_type = psa_get_key_type(&attr); block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type); /* Expansion due to the addition of the MAC. */ transform_expansion += transform->maclen; /* Expansion due to the addition of CBC padding; * Theoretically up to 256 bytes, but we never use * more than the block size of the underlying cipher. */ transform_expansion += block_size; /* For TLS 1.2 or higher, an explicit IV is added * after the record header. */ #if defined(MBEDTLS_SSL_PROTO_TLS1_2) transform_expansion += block_size; #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ } else { MBEDTLS_SSL_DEBUG_MSG(1, ("Unsupported psa_alg spotted in mbedtls_ssl_get_record_expansion()")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } #else switch (mbedtls_cipher_get_cipher_mode(&transform->cipher_ctx_enc)) { case MBEDTLS_MODE_GCM: case MBEDTLS_MODE_CCM: case MBEDTLS_MODE_CHACHAPOLY: case MBEDTLS_MODE_STREAM: transform_expansion = transform->minlen; break; case MBEDTLS_MODE_CBC: block_size = mbedtls_cipher_get_block_size( &transform->cipher_ctx_enc); /* Expansion due to the addition of the MAC. */ transform_expansion += transform->maclen; /* Expansion due to the addition of CBC padding; * Theoretically up to 256 bytes, but we never use * more than the block size of the underlying cipher. */ transform_expansion += block_size; /* For TLS 1.2 or higher, an explicit IV is added * after the record header. */ #if defined(MBEDTLS_SSL_PROTO_TLS1_2) transform_expansion += block_size; #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ break; default: MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen")); return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) if (transform->out_cid_len != 0) { transform_expansion += MBEDTLS_SSL_MAX_CID_EXPANSION; } #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */ return (int) (out_hdr_len + transform_expansion); } #if defined(MBEDTLS_SSL_RENEGOTIATION) /* * Check record counters and renegotiate if they're above the limit. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_check_ctr_renegotiate(mbedtls_ssl_context *ssl) { size_t ep_len = mbedtls_ssl_ep_len(ssl); int in_ctr_cmp; int out_ctr_cmp; if (mbedtls_ssl_is_handshake_over(ssl) == 0 || ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING || ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED) { return 0; } in_ctr_cmp = memcmp(ssl->in_ctr + ep_len, &ssl->conf->renego_period[ep_len], MBEDTLS_SSL_SEQUENCE_NUMBER_LEN - ep_len); out_ctr_cmp = memcmp(&ssl->cur_out_ctr[ep_len], &ssl->conf->renego_period[ep_len], sizeof(ssl->cur_out_ctr) - ep_len); if (in_ctr_cmp <= 0 && out_ctr_cmp <= 0) { return 0; } MBEDTLS_SSL_DEBUG_MSG(1, ("record counter limit reached: renegotiate")); return mbedtls_ssl_renegotiate(ssl); } #endif /* MBEDTLS_SSL_RENEGOTIATION */ #if defined(MBEDTLS_SSL_PROTO_TLS1_3) #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C) MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_check_new_session_ticket(mbedtls_ssl_context *ssl) { if ((ssl->in_hslen == mbedtls_ssl_hs_hdr_len(ssl)) || (ssl->in_msg[0] != MBEDTLS_SSL_HS_NEW_SESSION_TICKET)) { return 0; } ssl->keep_current_message = 1; MBEDTLS_SSL_DEBUG_MSG(3, ("NewSessionTicket received")); mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET); return MBEDTLS_ERR_SSL_WANT_READ; } #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls13_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl) { MBEDTLS_SSL_DEBUG_MSG(3, ("received post-handshake message")); #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C) if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT) { int ret = ssl_tls13_check_new_session_ticket(ssl); if (ret != 0) { return ret; } } #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */ /* Fail in all other cases. */ return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; } #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ #if defined(MBEDTLS_SSL_PROTO_TLS1_2) /* This function is called from mbedtls_ssl_read() when a handshake message is * received after the initial handshake. In this context, handshake messages * may only be sent for the purpose of initiating renegotiations. * * This function is introduced as a separate helper since the handling * of post-handshake handshake messages changes significantly in TLS 1.3, * and having a helper function allows to distinguish between TLS <= 1.2 and * TLS 1.3 in the future without bloating the logic of mbedtls_ssl_read(). */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_tls12_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; /* * - For client-side, expect SERVER_HELLO_REQUEST. * - For server-side, expect CLIENT_HELLO. * - Fail (TLS) or silently drop record (DTLS) in other cases. */ #if defined(MBEDTLS_SSL_CLI_C) if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT && (ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_REQUEST || ssl->in_hslen != mbedtls_ssl_hs_hdr_len(ssl))) { MBEDTLS_SSL_DEBUG_MSG(1, ("handshake received (not HelloRequest)")); /* With DTLS, drop the packet (probably from last handshake) */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { return 0; } #endif return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; } #endif /* MBEDTLS_SSL_CLI_C */ #if defined(MBEDTLS_SSL_SRV_C) if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER && ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO) { MBEDTLS_SSL_DEBUG_MSG(1, ("handshake received (not ClientHello)")); /* With DTLS, drop the packet (probably from last handshake) */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { return 0; } #endif return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; } #endif /* MBEDTLS_SSL_SRV_C */ #if defined(MBEDTLS_SSL_RENEGOTIATION) /* Determine whether renegotiation attempt should be accepted */ if (!(ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED || (ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION && ssl->conf->allow_legacy_renegotiation == MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION))) { /* * Accept renegotiation request */ /* DTLS clients need to know renego is server-initiated */ #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM && ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT) { ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING; } #endif ret = mbedtls_ssl_start_renegotiation(ssl); if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO && ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_start_renegotiation", ret); return ret; } } else #endif /* MBEDTLS_SSL_RENEGOTIATION */ { /* * Refuse renegotiation */ MBEDTLS_SSL_DEBUG_MSG(3, ("refusing renegotiation, sending alert")); if ((ret = mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_WARNING, MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION)) != 0) { return ret; } } return 0; } #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl) { /* Check protocol version and dispatch accordingly. */ #if defined(MBEDTLS_SSL_PROTO_TLS1_3) if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) { return ssl_tls13_handle_hs_message_post_handshake(ssl); } #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */ #if defined(MBEDTLS_SSL_PROTO_TLS1_2) if (ssl->tls_version <= MBEDTLS_SSL_VERSION_TLS1_2) { return ssl_tls12_handle_hs_message_post_handshake(ssl); } #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ /* Should never happen */ return MBEDTLS_ERR_SSL_INTERNAL_ERROR; } /* * Receive application data decrypted from the SSL layer */ int mbedtls_ssl_read(mbedtls_ssl_context *ssl, unsigned char *buf, size_t len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t n; if (ssl == NULL || ssl->conf == NULL) { return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } MBEDTLS_SSL_DEBUG_MSG(2, ("=> read")); #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { return ret; } if (ssl->handshake != NULL && ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING) { if ((ret = mbedtls_ssl_flight_transmit(ssl)) != 0) { return ret; } } } #endif /* * Check if renegotiation is necessary and/or handshake is * in process. If yes, perform/continue, and fall through * if an unexpected packet is received while the client * is waiting for the ServerHello. * * (There is no equivalent to the last condition on * the server-side as it is not treated as within * a handshake while waiting for the ClientHello * after a renegotiation request.) */ #if defined(MBEDTLS_SSL_RENEGOTIATION) ret = ssl_check_ctr_renegotiate(ssl); if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO && ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_check_ctr_renegotiate", ret); return ret; } #endif if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) { ret = mbedtls_ssl_handshake(ssl); if (ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO && ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret); return ret; } } /* Loop as long as no application data record is available */ while (ssl->in_offt == NULL) { /* Start timer if not already running */ if (ssl->f_get_timer != NULL && ssl->f_get_timer(ssl->p_timer) == -1) { mbedtls_ssl_set_timer(ssl, ssl->conf->read_timeout); } if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) { if (ret == MBEDTLS_ERR_SSL_CONN_EOF) { return 0; } MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); return ret; } if (ssl->in_msglen == 0 && ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA) { /* * OpenSSL sends empty messages to randomize the IV */ if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) { if (ret == MBEDTLS_ERR_SSL_CONN_EOF) { return 0; } MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_read_record", ret); return ret; } } if (ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE) { ret = ssl_handle_hs_message_post_handshake(ssl); if (ret != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_handle_hs_message_post_handshake", ret); return ret; } /* At this point, we don't know whether the renegotiation triggered * by the post-handshake message has been completed or not. The cases * to consider are the following: * 1) The renegotiation is complete. In this case, no new record * has been read yet. * 2) The renegotiation is incomplete because the client received * an application data record while awaiting the ServerHello. * 3) The renegotiation is incomplete because the client received * a non-handshake, non-application data message while awaiting * the ServerHello. * * In each of these cases, looping will be the proper action: * - For 1), the next iteration will read a new record and check * if it's application data. * - For 2), the loop condition isn't satisfied as application data * is present, hence continue is the same as break * - For 3), the loop condition is satisfied and read_record * will re-deliver the message that was held back by the client * when expecting the ServerHello. */ continue; } #if defined(MBEDTLS_SSL_RENEGOTIATION) else if (ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) { if (ssl->conf->renego_max_records >= 0) { if (++ssl->renego_records_seen > ssl->conf->renego_max_records) { MBEDTLS_SSL_DEBUG_MSG(1, ("renegotiation requested, " "but not honored by client")); return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; } } } #endif /* MBEDTLS_SSL_RENEGOTIATION */ /* Fatal and closure alerts handled by mbedtls_ssl_read_record() */ if (ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT) { MBEDTLS_SSL_DEBUG_MSG(2, ("ignoring non-fatal non-closure alert")); return MBEDTLS_ERR_SSL_WANT_READ; } if (ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA) { MBEDTLS_SSL_DEBUG_MSG(1, ("bad application data message")); return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE; } ssl->in_offt = ssl->in_msg; /* We're going to return something now, cancel timer, * except if handshake (renegotiation) is in progress */ if (mbedtls_ssl_is_handshake_over(ssl) == 1) { mbedtls_ssl_set_timer(ssl, 0); } #if defined(MBEDTLS_SSL_PROTO_DTLS) /* If we requested renego but received AppData, resend HelloRequest. * Do it now, after setting in_offt, to avoid taking this branch * again if ssl_write_hello_request() returns WANT_WRITE */ #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION) if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER && ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING) { if ((ret = mbedtls_ssl_resend_hello_request(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_resend_hello_request", ret); return ret; } } #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */ #endif /* MBEDTLS_SSL_PROTO_DTLS */ } n = (len < ssl->in_msglen) ? len : ssl->in_msglen; if (len != 0) { memcpy(buf, ssl->in_offt, n); ssl->in_msglen -= n; } /* Zeroising the plaintext buffer to erase unused application data from the memory. */ mbedtls_platform_zeroize(ssl->in_offt, n); if (ssl->in_msglen == 0) { /* all bytes consumed */ ssl->in_offt = NULL; ssl->keep_current_message = 0; } else { /* more data available */ ssl->in_offt += n; } MBEDTLS_SSL_DEBUG_MSG(2, ("<= read")); return (int) n; } /* * Send application data to be encrypted by the SSL layer, taking care of max * fragment length and buffer size. * * According to RFC 5246 Section 6.2.1: * * Zero-length fragments of Application data MAY be sent as they are * potentially useful as a traffic analysis countermeasure. * * Therefore, it is possible that the input message length is 0 and the * corresponding return code is 0 on success. */ MBEDTLS_CHECK_RETURN_CRITICAL static int ssl_write_real(mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len) { int ret = mbedtls_ssl_get_max_out_record_payload(ssl); const size_t max_len = (size_t) ret; if (ret < 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_get_max_out_record_payload", ret); return ret; } if (len > max_len) { #if defined(MBEDTLS_SSL_PROTO_DTLS) if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { MBEDTLS_SSL_DEBUG_MSG(1, ("fragment larger than the (negotiated) " "maximum fragment length: %" MBEDTLS_PRINTF_SIZET " > %" MBEDTLS_PRINTF_SIZET, len, max_len)); return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } else #endif len = max_len; } if (ssl->out_left != 0) { /* * The user has previously tried to send the data and * MBEDTLS_ERR_SSL_WANT_WRITE or the message was only partially * written. In this case, we expect the high-level write function * (e.g. mbedtls_ssl_write()) to be called with the same parameters */ if ((ret = mbedtls_ssl_flush_output(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flush_output", ret); return ret; } } else { /* * The user is trying to send a message the first time, so we need to * copy the data into the internal buffers and setup the data structure * to keep track of partial writes */ ssl->out_msglen = len; ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA; if (len > 0) { memcpy(ssl->out_msg, buf, len); } if ((ret = mbedtls_ssl_write_record(ssl, SSL_FORCE_FLUSH)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret); return ret; } } return (int) len; } /* * Write application data (public-facing wrapper) */ int mbedtls_ssl_write(mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; MBEDTLS_SSL_DEBUG_MSG(2, ("=> write")); if (ssl == NULL || ssl->conf == NULL) { return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } #if defined(MBEDTLS_SSL_RENEGOTIATION) if ((ret = ssl_check_ctr_renegotiate(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "ssl_check_ctr_renegotiate", ret); return ret; } #endif if (ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER) { if ((ret = mbedtls_ssl_handshake(ssl)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret); return ret; } } ret = ssl_write_real(ssl, buf, len); MBEDTLS_SSL_DEBUG_MSG(2, ("<= write")); return ret; } /* * Notify the peer that the connection is being closed */ int mbedtls_ssl_close_notify(mbedtls_ssl_context *ssl) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; if (ssl == NULL || ssl->conf == NULL) { return MBEDTLS_ERR_SSL_BAD_INPUT_DATA; } MBEDTLS_SSL_DEBUG_MSG(2, ("=> write close notify")); if (mbedtls_ssl_is_handshake_over(ssl) == 1) { if ((ret = mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_WARNING, MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY)) != 0) { MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_send_alert_message", ret); return ret; } } MBEDTLS_SSL_DEBUG_MSG(2, ("<= write close notify")); return 0; } void mbedtls_ssl_transform_free(mbedtls_ssl_transform *transform) { if (transform == NULL) { return; } #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_destroy_key(transform->psa_key_enc); psa_destroy_key(transform->psa_key_dec); #else mbedtls_cipher_free(&transform->cipher_ctx_enc); mbedtls_cipher_free(&transform->cipher_ctx_dec); #endif /* MBEDTLS_USE_PSA_CRYPTO */ #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_destroy_key(transform->psa_mac_enc); psa_destroy_key(transform->psa_mac_dec); #else mbedtls_md_free(&transform->md_ctx_enc); mbedtls_md_free(&transform->md_ctx_dec); #endif /* MBEDTLS_USE_PSA_CRYPTO */ #endif mbedtls_platform_zeroize(transform, sizeof(mbedtls_ssl_transform)); } void mbedtls_ssl_set_inbound_transform(mbedtls_ssl_context *ssl, mbedtls_ssl_transform *transform) { ssl->transform_in = transform; memset(ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN); } void mbedtls_ssl_set_outbound_transform(mbedtls_ssl_context *ssl, mbedtls_ssl_transform *transform) { ssl->transform_out = transform; memset(ssl->cur_out_ctr, 0, sizeof(ssl->cur_out_ctr)); } #if defined(MBEDTLS_SSL_PROTO_DTLS) void mbedtls_ssl_buffering_free(mbedtls_ssl_context *ssl) { unsigned offset; mbedtls_ssl_handshake_params * const hs = ssl->handshake; if (hs == NULL) { return; } ssl_free_buffered_record(ssl); for (offset = 0; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++) { ssl_buffering_free_slot(ssl, offset); } } static void ssl_buffering_free_slot(mbedtls_ssl_context *ssl, uint8_t slot) { mbedtls_ssl_handshake_params * const hs = ssl->handshake; mbedtls_ssl_hs_buffer * const hs_buf = &hs->buffering.hs[slot]; if (slot >= MBEDTLS_SSL_MAX_BUFFERED_HS) { return; } if (hs_buf->is_valid == 1) { hs->buffering.total_bytes_buffered -= hs_buf->data_len; mbedtls_zeroize_and_free(hs_buf->data, hs_buf->data_len); memset(hs_buf, 0, sizeof(mbedtls_ssl_hs_buffer)); } } #endif /* MBEDTLS_SSL_PROTO_DTLS */ /* * Convert version numbers to/from wire format * and, for DTLS, to/from TLS equivalent. * * For TLS this is the identity. * For DTLS, map as follows, then use 1's complement (v -> ~v): * 1.x <-> 3.x+1 for x != 0 (DTLS 1.2 based on TLS 1.2) * DTLS 1.0 is stored as TLS 1.1 internally */ void mbedtls_ssl_write_version(unsigned char version[2], int transport, mbedtls_ssl_protocol_version tls_version) { uint16_t tls_version_formatted; #if defined(MBEDTLS_SSL_PROTO_DTLS) if (transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { tls_version_formatted = ~(tls_version - (tls_version == 0x0302 ? 0x0202 : 0x0201)); } else #else ((void) transport); #endif { tls_version_formatted = (uint16_t) tls_version; } MBEDTLS_PUT_UINT16_BE(tls_version_formatted, version, 0); } uint16_t mbedtls_ssl_read_version(const unsigned char version[2], int transport) { uint16_t tls_version = MBEDTLS_GET_UINT16_BE(version, 0); #if defined(MBEDTLS_SSL_PROTO_DTLS) if (transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) { tls_version = ~(tls_version - (tls_version == 0xfeff ? 0x0202 : 0x0201)); } #else ((void) transport); #endif return tls_version; } /* * Send pending fatal alert. * 0, No alert message. * !0, if mbedtls_ssl_send_alert_message() returned in error, the error code it * returned, ssl->alert_reason otherwise. */ int mbedtls_ssl_handle_pending_alert(mbedtls_ssl_context *ssl) { int ret; /* No pending alert, return success*/ if (ssl->send_alert == 0) { return 0; } ret = mbedtls_ssl_send_alert_message(ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, ssl->alert_type); /* If mbedtls_ssl_send_alert_message() returned with MBEDTLS_ERR_SSL_WANT_WRITE, * do not clear the alert to be able to send it later. */ if (ret != MBEDTLS_ERR_SSL_WANT_WRITE) { ssl->send_alert = 0; } if (ret != 0) { return ret; } return ssl->alert_reason; } /* * Set pending fatal alert flag. */ void mbedtls_ssl_pend_fatal_alert(mbedtls_ssl_context *ssl, unsigned char alert_type, int alert_reason) { ssl->send_alert = 1; ssl->alert_type = alert_type; ssl->alert_reason = alert_reason; } #endif /* MBEDTLS_SSL_TLS_C */