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mbedtls/library/pem.c
Valerio Setti 4bb5740a7d Revert "pem: auto add newlines to header/footer in mbedtls_pem_write_buffer()" 
This reverts commit 180915018d.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
2023-12-19 07:48:38 +01:00

520 lines
14 KiB
C
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/*
* Privacy Enhanced Mail (PEM) decoding
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#include "common.h"
#if defined(MBEDTLS_PEM_PARSE_C) || defined(MBEDTLS_PEM_WRITE_C)
#include "mbedtls/pem.h"
#include "mbedtls/base64.h"
#include "mbedtls/des.h"
#include "mbedtls/aes.h"
#include "mbedtls/md.h"
#include "mbedtls/cipher.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include <string.h>
#include "mbedtls/platform.h"
#if defined(MBEDTLS_USE_PSA_CRYPTO)
#include "psa/crypto.h"
#endif
#if defined(MBEDTLS_MD_CAN_MD5) && \
defined(MBEDTLS_CIPHER_MODE_CBC) && \
(defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C))
#define PEM_RFC1421
#endif /* MBEDTLS_MD_CAN_MD5 &&
MBEDTLS_CIPHER_MODE_CBC &&
( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
#if defined(MBEDTLS_PEM_PARSE_C)
void mbedtls_pem_init(mbedtls_pem_context *ctx)
{
memset(ctx, 0, sizeof(mbedtls_pem_context));
}
#if defined(PEM_RFC1421)
/*
* Read a 16-byte hex string and convert it to binary
*/
static int pem_get_iv(const unsigned char *s, unsigned char *iv,
size_t iv_len)
{
size_t i, j, k;
memset(iv, 0, iv_len);
for (i = 0; i < iv_len * 2; i++, s++) {
if (*s >= '0' && *s <= '9') {
j = *s - '0';
} else
if (*s >= 'A' && *s <= 'F') {
j = *s - '7';
} else
if (*s >= 'a' && *s <= 'f') {
j = *s - 'W';
} else {
return MBEDTLS_ERR_PEM_INVALID_ENC_IV;
}
k = ((i & 1) != 0) ? j : j << 4;
iv[i >> 1] = (unsigned char) (iv[i >> 1] | k);
}
return 0;
}
static int pem_pbkdf1(unsigned char *key, size_t keylen,
unsigned char *iv,
const unsigned char *pwd, size_t pwdlen)
{
mbedtls_md_context_t md5_ctx;
const mbedtls_md_info_t *md5_info;
unsigned char md5sum[16];
size_t use_len;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_md_init(&md5_ctx);
/* Prepare the context. (setup() errors gracefully on NULL info.) */
md5_info = mbedtls_md_info_from_type(MBEDTLS_MD_MD5);
if ((ret = mbedtls_md_setup(&md5_ctx, md5_info, 0)) != 0) {
goto exit;
}
/*
* key[ 0..15] = MD5(pwd || IV)
*/
if ((ret = mbedtls_md_starts(&md5_ctx)) != 0) {
goto exit;
}
if ((ret = mbedtls_md_update(&md5_ctx, pwd, pwdlen)) != 0) {
goto exit;
}
if ((ret = mbedtls_md_update(&md5_ctx, iv, 8)) != 0) {
goto exit;
}
if ((ret = mbedtls_md_finish(&md5_ctx, md5sum)) != 0) {
goto exit;
}
if (keylen <= 16) {
memcpy(key, md5sum, keylen);
goto exit;
}
memcpy(key, md5sum, 16);
/*
* key[16..23] = MD5(key[ 0..15] || pwd || IV])
*/
if ((ret = mbedtls_md_starts(&md5_ctx)) != 0) {
goto exit;
}
if ((ret = mbedtls_md_update(&md5_ctx, md5sum, 16)) != 0) {
goto exit;
}
if ((ret = mbedtls_md_update(&md5_ctx, pwd, pwdlen)) != 0) {
goto exit;
}
if ((ret = mbedtls_md_update(&md5_ctx, iv, 8)) != 0) {
goto exit;
}
if ((ret = mbedtls_md_finish(&md5_ctx, md5sum)) != 0) {
goto exit;
}
use_len = 16;
if (keylen < 32) {
use_len = keylen - 16;
}
memcpy(key + 16, md5sum, use_len);
exit:
mbedtls_md_free(&md5_ctx);
mbedtls_platform_zeroize(md5sum, 16);
return ret;
}
#if defined(MBEDTLS_DES_C)
/*
* Decrypt with DES-CBC, using PBKDF1 for key derivation
*/
static int pem_des_decrypt(unsigned char des_iv[8],
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen)
{
mbedtls_des_context des_ctx;
unsigned char des_key[8];
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_des_init(&des_ctx);
if ((ret = pem_pbkdf1(des_key, 8, des_iv, pwd, pwdlen)) != 0) {
goto exit;
}
if ((ret = mbedtls_des_setkey_dec(&des_ctx, des_key)) != 0) {
goto exit;
}
ret = mbedtls_des_crypt_cbc(&des_ctx, MBEDTLS_DES_DECRYPT, buflen,
des_iv, buf, buf);
exit:
mbedtls_des_free(&des_ctx);
mbedtls_platform_zeroize(des_key, 8);
return ret;
}
/*
* Decrypt with 3DES-CBC, using PBKDF1 for key derivation
*/
static int pem_des3_decrypt(unsigned char des3_iv[8],
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen)
{
mbedtls_des3_context des3_ctx;
unsigned char des3_key[24];
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_des3_init(&des3_ctx);
if ((ret = pem_pbkdf1(des3_key, 24, des3_iv, pwd, pwdlen)) != 0) {
goto exit;
}
if ((ret = mbedtls_des3_set3key_dec(&des3_ctx, des3_key)) != 0) {
goto exit;
}
ret = mbedtls_des3_crypt_cbc(&des3_ctx, MBEDTLS_DES_DECRYPT, buflen,
des3_iv, buf, buf);
exit:
mbedtls_des3_free(&des3_ctx);
mbedtls_platform_zeroize(des3_key, 24);
return ret;
}
#endif /* MBEDTLS_DES_C */
#if defined(MBEDTLS_AES_C)
/*
* Decrypt with AES-XXX-CBC, using PBKDF1 for key derivation
*/
static int pem_aes_decrypt(unsigned char aes_iv[16], unsigned int keylen,
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen)
{
mbedtls_aes_context aes_ctx;
unsigned char aes_key[32];
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_aes_init(&aes_ctx);
if ((ret = pem_pbkdf1(aes_key, keylen, aes_iv, pwd, pwdlen)) != 0) {
goto exit;
}
if ((ret = mbedtls_aes_setkey_dec(&aes_ctx, aes_key, keylen * 8)) != 0) {
goto exit;
}
ret = mbedtls_aes_crypt_cbc(&aes_ctx, MBEDTLS_AES_DECRYPT, buflen,
aes_iv, buf, buf);
exit:
mbedtls_aes_free(&aes_ctx);
mbedtls_platform_zeroize(aes_key, keylen);
return ret;
}
#endif /* MBEDTLS_AES_C */
#endif /* PEM_RFC1421 */
int mbedtls_pem_read_buffer(mbedtls_pem_context *ctx, const char *header, const char *footer,
const unsigned char *data, const unsigned char *pwd,
size_t pwdlen, size_t *use_len)
{
int ret, enc;
size_t len;
unsigned char *buf;
const unsigned char *s1, *s2, *end;
#if defined(PEM_RFC1421)
unsigned char pem_iv[16];
mbedtls_cipher_type_t enc_alg = MBEDTLS_CIPHER_NONE;
#else
((void) pwd);
((void) pwdlen);
#endif /* PEM_RFC1421 */
if (ctx == NULL) {
return MBEDTLS_ERR_PEM_BAD_INPUT_DATA;
}
s1 = (unsigned char *) strstr((const char *) data, header);
if (s1 == NULL) {
return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
}
s2 = (unsigned char *) strstr((const char *) data, footer);
if (s2 == NULL || s2 <= s1) {
return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
}
s1 += strlen(header);
if (*s1 == ' ') {
s1++;
}
if (*s1 == '\r') {
s1++;
}
if (*s1 == '\n') {
s1++;
} else {
return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
}
end = s2;
end += strlen(footer);
if (*end == ' ') {
end++;
}
if (*end == '\r') {
end++;
}
if (*end == '\n') {
end++;
}
*use_len = end - data;
enc = 0;
if (s2 - s1 >= 22 && memcmp(s1, "Proc-Type: 4,ENCRYPTED", 22) == 0) {
#if defined(PEM_RFC1421)
enc++;
s1 += 22;
if (*s1 == '\r') {
s1++;
}
if (*s1 == '\n') {
s1++;
} else {
return MBEDTLS_ERR_PEM_INVALID_DATA;
}
#if defined(MBEDTLS_DES_C)
if (s2 - s1 >= 23 && memcmp(s1, "DEK-Info: DES-EDE3-CBC,", 23) == 0) {
enc_alg = MBEDTLS_CIPHER_DES_EDE3_CBC;
s1 += 23;
if (s2 - s1 < 16 || pem_get_iv(s1, pem_iv, 8) != 0) {
return MBEDTLS_ERR_PEM_INVALID_ENC_IV;
}
s1 += 16;
} else if (s2 - s1 >= 18 && memcmp(s1, "DEK-Info: DES-CBC,", 18) == 0) {
enc_alg = MBEDTLS_CIPHER_DES_CBC;
s1 += 18;
if (s2 - s1 < 16 || pem_get_iv(s1, pem_iv, 8) != 0) {
return MBEDTLS_ERR_PEM_INVALID_ENC_IV;
}
s1 += 16;
}
#endif /* MBEDTLS_DES_C */
#if defined(MBEDTLS_AES_C)
if (s2 - s1 >= 14 && memcmp(s1, "DEK-Info: AES-", 14) == 0) {
if (s2 - s1 < 22) {
return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG;
} else if (memcmp(s1, "DEK-Info: AES-128-CBC,", 22) == 0) {
enc_alg = MBEDTLS_CIPHER_AES_128_CBC;
} else if (memcmp(s1, "DEK-Info: AES-192-CBC,", 22) == 0) {
enc_alg = MBEDTLS_CIPHER_AES_192_CBC;
} else if (memcmp(s1, "DEK-Info: AES-256-CBC,", 22) == 0) {
enc_alg = MBEDTLS_CIPHER_AES_256_CBC;
} else {
return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG;
}
s1 += 22;
if (s2 - s1 < 32 || pem_get_iv(s1, pem_iv, 16) != 0) {
return MBEDTLS_ERR_PEM_INVALID_ENC_IV;
}
s1 += 32;
}
#endif /* MBEDTLS_AES_C */
if (enc_alg == MBEDTLS_CIPHER_NONE) {
return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG;
}
if (*s1 == '\r') {
s1++;
}
if (*s1 == '\n') {
s1++;
} else {
return MBEDTLS_ERR_PEM_INVALID_DATA;
}
#else
return MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE;
#endif /* PEM_RFC1421 */
}
if (s1 >= s2) {
return MBEDTLS_ERR_PEM_INVALID_DATA;
}
ret = mbedtls_base64_decode(NULL, 0, &len, s1, s2 - s1);
if (ret == MBEDTLS_ERR_BASE64_INVALID_CHARACTER) {
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PEM_INVALID_DATA, ret);
}
if ((buf = mbedtls_calloc(1, len)) == NULL) {
return MBEDTLS_ERR_PEM_ALLOC_FAILED;
}
if ((ret = mbedtls_base64_decode(buf, len, &len, s1, s2 - s1)) != 0) {
mbedtls_zeroize_and_free(buf, len);
return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PEM_INVALID_DATA, ret);
}
if (enc != 0) {
#if defined(PEM_RFC1421)
if (pwd == NULL) {
mbedtls_zeroize_and_free(buf, len);
return MBEDTLS_ERR_PEM_PASSWORD_REQUIRED;
}
ret = 0;
#if defined(MBEDTLS_DES_C)
if (enc_alg == MBEDTLS_CIPHER_DES_EDE3_CBC) {
ret = pem_des3_decrypt(pem_iv, buf, len, pwd, pwdlen);
} else if (enc_alg == MBEDTLS_CIPHER_DES_CBC) {
ret = pem_des_decrypt(pem_iv, buf, len, pwd, pwdlen);
}
#endif /* MBEDTLS_DES_C */
#if defined(MBEDTLS_AES_C)
if (enc_alg == MBEDTLS_CIPHER_AES_128_CBC) {
ret = pem_aes_decrypt(pem_iv, 16, buf, len, pwd, pwdlen);
} else if (enc_alg == MBEDTLS_CIPHER_AES_192_CBC) {
ret = pem_aes_decrypt(pem_iv, 24, buf, len, pwd, pwdlen);
} else if (enc_alg == MBEDTLS_CIPHER_AES_256_CBC) {
ret = pem_aes_decrypt(pem_iv, 32, buf, len, pwd, pwdlen);
}
#endif /* MBEDTLS_AES_C */
if (ret != 0) {
mbedtls_free(buf);
return ret;
}
/*
* The result will be ASN.1 starting with a SEQUENCE tag, with 1 to 3
* length bytes (allow 4 to be sure) in all known use cases.
*
* Use that as a heuristic to try to detect password mismatches.
*/
if (len <= 2 || buf[0] != 0x30 || buf[1] > 0x83) {
mbedtls_zeroize_and_free(buf, len);
return MBEDTLS_ERR_PEM_PASSWORD_MISMATCH;
}
#else
mbedtls_zeroize_and_free(buf, len);
return MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE;
#endif /* PEM_RFC1421 */
}
ctx->buf = buf;
ctx->buflen = len;
return 0;
}
void mbedtls_pem_free(mbedtls_pem_context *ctx)
{
if (ctx->buf != NULL) {
mbedtls_zeroize_and_free(ctx->buf, ctx->buflen);
}
mbedtls_free(ctx->info);
mbedtls_platform_zeroize(ctx, sizeof(mbedtls_pem_context));
}
#endif /* MBEDTLS_PEM_PARSE_C */
#if defined(MBEDTLS_PEM_WRITE_C)
int mbedtls_pem_write_buffer(const char *header, const char *footer,
const unsigned char *der_data, size_t der_len,
unsigned char *buf, size_t buf_len, size_t *olen)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *encode_buf = NULL, *c, *p = buf;
size_t len = 0, use_len, add_len = 0;
mbedtls_base64_encode(NULL, 0, &use_len, der_data, der_len);
add_len = strlen(header) + strlen(footer) + (((use_len > 2) ? (use_len - 2) : 0) / 64) + 1;
if (use_len + add_len > buf_len) {
*olen = use_len + add_len;
return MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL;
}
if (use_len != 0 &&
((encode_buf = mbedtls_calloc(1, use_len)) == NULL)) {
return MBEDTLS_ERR_PEM_ALLOC_FAILED;
}
if ((ret = mbedtls_base64_encode(encode_buf, use_len, &use_len, der_data,
der_len)) != 0) {
mbedtls_free(encode_buf);
return ret;
}
memcpy(p, header, strlen(header));
p += strlen(header);
c = encode_buf;
while (use_len) {
len = (use_len > 64) ? 64 : use_len;
memcpy(p, c, len);
use_len -= len;
p += len;
c += len;
*p++ = '\n';
}
memcpy(p, footer, strlen(footer));
p += strlen(footer);
*p++ = '\0';
*olen = p - buf;
/* Clean any remaining data previously written to the buffer */
memset(buf + *olen, 0, buf_len - *olen);
mbedtls_free(encode_buf);
return 0;
}
#endif /* MBEDTLS_PEM_WRITE_C */
#endif /* MBEDTLS_PEM_PARSE_C || MBEDTLS_PEM_WRITE_C */
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