Merge branch 'iotssl-629-der-trailing-bytes'

Fixes bug in mbedtls_x509_crt_parse that caused trailing extra data in the
buffer following DER certificates to be included in the raw representation.

ChangeLog

@@ -14,6 +14,8 @@ Bugfix
    * Fix an issue that caused valid certificates to be rejected whenever an
      expired or not yet valid certificate was parsed before a valid certificate
      in the trusted certificate list.
+   * Fix bug in mbedtls_x509_crt_parse that caused trailing extra data in the 
+     buffer after DER certificates to be included in the raw representation.
 
 Changes
    * On ARM platforms, when compiling with -O0 with GCC, Clang or armcc5,

library/x509_crt.c

@@ -677,14 +677,9 @@ static int x509_crt_parse_der_core( mbedtls_x509_crt *crt, const unsigned char *
     if( crt == NULL || buf == NULL )
         return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
 
-    p = mbedtls_calloc( 1, len = buflen );
-    if( p == NULL )
-        return( MBEDTLS_ERR_X509_ALLOC_FAILED );
-
-    memcpy( p, buf, buflen );
-
-    crt->raw.p = p;
-    crt->raw.len = len;
+    // Use the original buffer until we figure out actual length
+    p = (unsigned char*) buf;
+    len = buflen;
     end = p + len;
 
     /*
@@ -708,6 +703,18 @@ static int x509_crt_parse_der_core( mbedtls_x509_crt *crt, const unsigned char *
     }
     crt_end = p + len;
 
+    // Create and populate a new buffer for the raw field
+    crt->raw.len = crt_end - buf;
+    crt->raw.p = p = mbedtls_calloc( 1, crt->raw.len );
+    if( p == NULL )
+        return( MBEDTLS_ERR_X509_ALLOC_FAILED );
+
+    memcpy( p, buf, crt->raw.len );
+
+    // Direct pointers to the new buffer 
+    p += crt->raw.len - len;
+    end = crt_end = p + len;
+
     /*
      * TBSCertificate  ::=  SEQUENCE  {
      */

tests/ssl-opt.sh

@@ -1559,6 +1559,64 @@ run_test    "Renego ext: gnutls client unsafe, server break legacy" \
             -S "received TLS_EMPTY_RENEGOTIATION_INFO\|found renegotiation extension" \
             -S "server hello, secure renegotiation extension"
 
+# Tests for silently dropping trailing extra bytes in .der certificates
+
+requires_gnutls
+run_test    "DER format: no trailing bytes" \
+            "$P_SRV crt_file=data_files/server5-der0.crt \
+             key_file=data_files/server5.key" \
+            "$G_CLI " \
+            0 \
+            -c "Handshake was completed" \
+
+requires_gnutls
+run_test    "DER format: with a trailing zero byte" \
+            "$P_SRV crt_file=data_files/server5-der1a.crt \
+             key_file=data_files/server5.key" \
+            "$G_CLI " \
+            0 \
+            -c "Handshake was completed" \
+
+requires_gnutls
+run_test    "DER format: with a trailing random byte" \
+            "$P_SRV crt_file=data_files/server5-der1b.crt \
+             key_file=data_files/server5.key" \
+            "$G_CLI " \
+            0 \
+            -c "Handshake was completed" \
+
+requires_gnutls
+run_test    "DER format: with 2 trailing random bytes" \
+            "$P_SRV crt_file=data_files/server5-der2.crt \
+             key_file=data_files/server5.key" \
+            "$G_CLI " \
+            0 \
+            -c "Handshake was completed" \
+
+requires_gnutls
+run_test    "DER format: with 4 trailing random bytes" \
+            "$P_SRV crt_file=data_files/server5-der4.crt \
+             key_file=data_files/server5.key" \
+            "$G_CLI " \
+            0 \
+            -c "Handshake was completed" \
+
+requires_gnutls
+run_test    "DER format: with 8 trailing random bytes" \
+            "$P_SRV crt_file=data_files/server5-der8.crt \
+             key_file=data_files/server5.key" \
+            "$G_CLI " \
+            0 \
+            -c "Handshake was completed" \
+
+requires_gnutls
+run_test    "DER format: with 9 trailing random bytes" \
+            "$P_SRV crt_file=data_files/server5-der9.crt \
+             key_file=data_files/server5.key" \
+            "$G_CLI " \
+            0 \
+            -c "Handshake was completed" \
+
 # Tests for auth_mode
 
 run_test    "Authentication: server badcert, client required" \

tests/suites/test_suite_x509parse.data

@@ -771,7 +771,7 @@ X509 Certificate ASN1 (Incorrect first tag)
 x509parse_crt:"":"":MBEDTLS_ERR_X509_INVALID_FORMAT
 
 X509 Certificate ASN1 (Correct first tag, data length does not match)
-x509parse_crt:"300000":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG
+x509parse_crt:"300000":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_OUT_OF_DATA
 
 X509 Certificate ASN1 (Correct first tag, no more data)
 x509parse_crt:"3000":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_OUT_OF_DATA