Merge branch 'mbedtls-2.4-restricted'

ChangeLog

@@ -2,6 +2,11 @@ mbed TLS ChangeLog (Sorted per branch, date)
 
 = mbed TLS 2.x.x branch released xxxx-xx-xx
 
+Security
+   * Removed MD5 from the allowed hash algorithms for CertificateRequest and
+     CertificateVerify messages, to prevent SLOTH attacks against TLS 1.2.
+     Introduced by interoperability fix for #513.
+
 Bugfix
    * Fix the redefinition of macro ssl_set_bio to an undefined symbol
      mbedtls_ssl_set_bio_timeout in compat-1.3.h, by removing it.
@@ -22,6 +27,9 @@ Bugfix
      cause buffer bound checks to be bypassed. Found by Eyal Itkin.
    * Fixed potential arithmetic overflow in mbedtls_base64_decode() that could
      cause buffer bound checks to be bypassed. Found by Eyal Itkin.
+   * Fixed multiple buffer overreads in mbedtls_pem_read_buffer() when parsing
+     the input string in PEM format to extract the different components. Found
+     by Eyal Itkin.
 
 = mbed TLS 2.4.1 branch released 2016-12-13
 

library/pem.c

@@ -249,7 +249,7 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
 
     enc = 0;
 
-    if( memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
+    if( s2 - s1 >= 22 && memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
     {
 #if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
     ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
@@ -262,22 +262,22 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
 
 
 #if defined(MBEDTLS_DES_C)
-        if( memcmp( s1, "DEK-Info: DES-EDE3-CBC,", 23 ) == 0 )
+        if( s2 - s1 >= 23 && memcmp( s1, "DEK-Info: DES-EDE3-CBC,", 23 ) == 0 )
         {
             enc_alg = MBEDTLS_CIPHER_DES_EDE3_CBC;
 
             s1 += 23;
-            if( pem_get_iv( s1, pem_iv, 8 ) != 0 )
+            if( s2 - s1 < 16 || pem_get_iv( s1, pem_iv, 8 ) != 0 )
                 return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );
 
             s1 += 16;
         }
-        else if( memcmp( s1, "DEK-Info: DES-CBC,", 18 ) == 0 )
+        else if( s2 - s1 >= 18 && memcmp( s1, "DEK-Info: DES-CBC,", 18 ) == 0 )
         {
             enc_alg = MBEDTLS_CIPHER_DES_CBC;
 
             s1 += 18;
-            if( pem_get_iv( s1, pem_iv, 8) != 0 )
+            if( s2 - s1 < 16 || pem_get_iv( s1, pem_iv, 8) != 0 )
                 return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );
 
             s1 += 16;
@@ -285,9 +285,11 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
 #endif /* MBEDTLS_DES_C */
 
 #if defined(MBEDTLS_AES_C)
-        if( memcmp( s1, "DEK-Info: AES-", 14 ) == 0 )
+        if( s2 - s1 >= 14 && memcmp( s1, "DEK-Info: AES-", 14 ) == 0 )
         {
-            if( memcmp( s1, "DEK-Info: AES-128-CBC,", 22 ) == 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;
@@ -297,7 +299,7 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
                 return( MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG );
 
             s1 += 22;
-            if( pem_get_iv( s1, pem_iv, 16 ) != 0 )
+            if( s2 - s1 < 32 || pem_get_iv( s1, pem_iv, 16 ) != 0 )
                 return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );
 
             s1 += 32;
@@ -316,7 +318,7 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
           ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
     }
 
-    if( s1 == s2 )
+    if( s1 >= s2 )
         return( MBEDTLS_ERR_PEM_INVALID_DATA );
 
     ret = mbedtls_base64_decode( NULL, 0, &len, s1, s2 - s1 );

library/ssl_tls.c

@@ -7653,8 +7653,7 @@ int mbedtls_ssl_set_calc_verify_md( mbedtls_ssl_context *ssl, int md )
 #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
 #if defined(MBEDTLS_MD5_C)
         case MBEDTLS_SSL_HASH_MD5:
-            ssl->handshake->calc_verify = ssl_calc_verify_tls;
+            return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
-            break;
 #endif
 #if defined(MBEDTLS_SHA1_C)
         case MBEDTLS_SSL_HASH_SHA1:

tests/suites/test_suite_pem.data

@@ -15,3 +15,12 @@ mbedtls_pem_write_buffer:"-----START TEST-----\n":"-----END TEST-----\n":"000102
 
 PEM write (exactly two lines + 1)
 mbedtls_pem_write_buffer:"-----START TEST-----\n":"-----END TEST-----\n":"000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F00":"-----START TEST-----\nAAECAwQFBgcICQoLDA0ODwABAgMEBQYHCAkKCwwNDg8AAQIDBAUGBwgJCgsMDQ4P\nAAECAwQFBgcICQoLDA0ODwABAgMEBQYHCAkKCwwNDg8AAQIDBAUGBwgJCgsMDQ4P\nAA==\n-----END TEST-----\n"
+
+PEM read (DES-EDE3-CBC + invalid iv)
+mbedtls_pem_read_buffer:"^":"$":"^\nProc-Type\: 4,ENCRYPTED\nDEK-Info\: DES-EDE3-CBC,00$":-4608
+
+PEM read (DES-CBC + invalid iv)
+mbedtls_pem_read_buffer:"^":"$":"^\nProc-Type\: 4,ENCRYPTED\nDEK-Info\: DES-CBC,00$":-4608
+
+PEM read (unknown encryption algorithm)
+mbedtls_pem_read_buffer:"^":"$":"^\nProc-Type\: 4,ENCRYPTED\nDEK-Info\: AES-,00$":-4736

tests/suites/test_suite_pem.function

@@ -3,12 +3,7 @@
 #include "mbedtls/pem.h"
 /* END_HEADER */
 
-/* BEGIN_DEPENDENCIES
+/* BEGIN_CASE depends_on:MBEDTLS_PEM_WRITE_C */
- * depends_on:MBEDTLS_PEM_WRITE_C
- * END_DEPENDENCIES
- */
-
-/* BEGIN_CASE */
 void mbedtls_pem_write_buffer( char *start, char *end, char *buf_str, char *result_str )
 {
     unsigned char buf[5000];
@@ -38,3 +33,20 @@ exit:
     mbedtls_free( check_buf );
 }
 /* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_AES_C:MBEDTLS_DES_C:MBEDTLS_MD5_C:MBEDTLS_CIPHER_MODE_CBC */
+void mbedtls_pem_read_buffer( char *header, char *footer, char *data, int ret )
+{
+    mbedtls_pem_context ctx;
+    size_t use_len = 0;
+
+    mbedtls_pem_init( &ctx );
+
+    TEST_ASSERT( mbedtls_pem_read_buffer( &ctx, header, footer,
+                                          (const unsigned char *)data, NULL, 0,
+                                          &use_len ) == ret );
+
+exit:
+    mbedtls_pem_free( &ctx );
+}
+/* END_CASE */