Merge remote-tracking branch 'restricted/pr/684' into mbedtls-2.22.0r0

ftheile · Apr 14, 2020 · ac15f84 · ac15f84
2 parents 105c996 + e62bdef
commit ac15f84
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Showing 11 changed files with 620 additions and 112 deletions.
diff --git a/ChangeLog b/ChangeLog
@@ -5,6 +5,10 @@ mbed TLS ChangeLog (Sorted per branch, date)
 New deprecations
    * Deprecate MBEDTLS_SSL_HW_RECORD_ACCEL that enables function hooks in the
      SSL module for hardware acceleration of individual records.
+   * Deprecate mbedtls_ssl_get_max_frag_len() in favour of
+     mbedtls_ssl_get_output_max_frag_len() and
+     mbedtls_ssl_get_input_max_frag_len() to be more precise about which max
+     fragment length is desired.
 
 Security
    * Fix issue in DTLS handling of new associations with the same parameters
@@ -37,6 +41,11 @@ Bugfix
 Changes
    * Mbed Crypto is no longer a Git submodule. The crypto part of the library
      is back directly in the present repository.
+   * Split mbedtls_ssl_get_max_frag_len() into
+     mbedtls_ssl_get_output_max_frag_len() and
+     mbedtls_ssl_get_input_max_frag_len() to ensure that a sufficient input
+     buffer is allocated by the server (if MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH
+     is defined), regardless of what MFL was configured for it.
 
 = mbed TLS 2.21.0 branch released 2020-02-20
 

diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
@@ -3523,18 +3523,61 @@ int mbedtls_ssl_get_record_expansion( const mbedtls_ssl_context *ssl );
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
 /**
- * \brief          Return the maximum fragment length (payload, in bytes).
- *                 This is the value negotiated with peer if any,
- *                 or the locally configured value.
+ * \brief          Return the maximum fragment length (payload, in bytes) for
+ *                 the output buffer. For the client, this is the configured
+ *                 value. For the server, it is the minimum of two - the
+ *                 configured value and the negotiated one.
  *
  * \sa             mbedtls_ssl_conf_max_frag_len()
  * \sa             mbedtls_ssl_get_max_record_payload()
  *
  * \param ssl      SSL context
  *
- * \return         Current maximum fragment length.
+ * \return         Current maximum fragment length for the output buffer.
  */
-size_t mbedtls_ssl_get_max_frag_len( const mbedtls_ssl_context *ssl );
+size_t mbedtls_ssl_get_output_max_frag_len( const mbedtls_ssl_context *ssl );
+
+/**
+ * \brief          Return the maximum fragment length (payload, in bytes) for
+ *                 the input buffer. This is the negotiated maximum fragment
+ *                 length, or, if there is none, MBEDTLS_SSL_MAX_CONTENT_LEN.
+ *                 If it is not defined either, the value is 2^14. This function
+ *                 works as its predecessor, \c mbedtls_ssl_get_max_frag_len().
+ *
+ * \sa             mbedtls_ssl_conf_max_frag_len()
+ * \sa             mbedtls_ssl_get_max_record_payload()
+ *
+ * \param ssl      SSL context
+ *
+ * \return         Current maximum fragment length for the output buffer.
+ */
+size_t mbedtls_ssl_get_input_max_frag_len( const mbedtls_ssl_context *ssl );
+
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+
+#if defined(MBEDTLS_DEPRECATED_WARNING)
+#define MBEDTLS_DEPRECATED    __attribute__((deprecated))
+#else
+#define MBEDTLS_DEPRECATED
+#endif
+
+/**
+ * \brief          This function is a deprecated approach to getting the max
+ *                 fragment length. Its an alias for
+ *                 \c mbedtls_ssl_get_output_max_frag_len(), as the behaviour
+ *                 is the same. See \c mbedtls_ssl_get_output_max_frag_len() for
+ *                 more detail.
+ *
+ * \sa             mbedtls_ssl_get_input_max_frag_len()
+ * \sa             mbedtls_ssl_get_output_max_frag_len()
+ *
+ * \param ssl      SSL context
+ *
+ * \return         Current maximum fragment length for the output buffer.
+ */
+MBEDTLS_DEPRECATED size_t mbedtls_ssl_get_max_frag_len(
+                                        const mbedtls_ssl_context *ssl );
+#endif /* MBEDTLS_DEPRECATED_REMOVED */
 #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
 
 /**
@@ -3555,7 +3598,8 @@ size_t mbedtls_ssl_get_max_frag_len( const mbedtls_ssl_context *ssl );
  *                 when record compression is enabled.
  *
  * \sa             mbedtls_ssl_set_mtu()
- * \sa             mbedtls_ssl_get_max_frag_len()
+ * \sa             mbedtls_ssl_get_output_max_frag_len()
+ * \sa             mbedtls_ssl_get_input_max_frag_len()
  * \sa             mbedtls_ssl_get_record_expansion()
  *
  * \param ssl      SSL context
@@ -3863,8 +3907,8 @@ int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
  *                 or negotiated with the peer), then:
  *                 - with TLS, less bytes than requested are written.
  *                 - with DTLS, MBEDTLS_ERR_SSL_BAD_INPUT_DATA is returned.
- *                 \c mbedtls_ssl_get_max_frag_len() may be used to query the
- *                 active maximum fragment length.
+ *                 \c mbedtls_ssl_get_output_max_frag_len() may be used to
+ *                 query the active maximum fragment length.
  *
  * \note           Attempting to write 0 bytes will result in an empty TLS
  *                 application record being sent.

diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
@@ -260,23 +260,23 @@
 static inline uint32_t mbedtls_ssl_get_output_buflen( const mbedtls_ssl_context *ctx )
 {
 #if defined (MBEDTLS_SSL_DTLS_CONNECTION_ID)
-    return (uint32_t) mbedtls_ssl_get_max_frag_len( ctx )
+    return (uint32_t) mbedtls_ssl_get_output_max_frag_len( ctx )
                + MBEDTLS_SSL_HEADER_LEN + MBEDTLS_SSL_PAYLOAD_OVERHEAD
                + MBEDTLS_SSL_CID_OUT_LEN_MAX;
 #else
-    return (uint32_t) mbedtls_ssl_get_max_frag_len( ctx )
+    return (uint32_t) mbedtls_ssl_get_output_max_frag_len( ctx )
                + MBEDTLS_SSL_HEADER_LEN + MBEDTLS_SSL_PAYLOAD_OVERHEAD;
 #endif
 }
 
 static inline uint32_t mbedtls_ssl_get_input_buflen( const mbedtls_ssl_context *ctx )
 {
 #if defined (MBEDTLS_SSL_DTLS_CONNECTION_ID)
-    return (uint32_t) mbedtls_ssl_get_max_frag_len( ctx )
+    return (uint32_t) mbedtls_ssl_get_input_max_frag_len( ctx )
                + MBEDTLS_SSL_HEADER_LEN + MBEDTLS_SSL_PAYLOAD_OVERHEAD
                + MBEDTLS_SSL_CID_IN_LEN_MAX;
 #else
-    return (uint32_t) mbedtls_ssl_get_max_frag_len( ctx )
+    return (uint32_t) mbedtls_ssl_get_input_max_frag_len( ctx )
                + MBEDTLS_SSL_HEADER_LEN + MBEDTLS_SSL_PAYLOAD_OVERHEAD;
 #endif
 }

diff --git a/library/ssl_msg.c b/library/ssl_msg.c
@@ -214,7 +214,7 @@ static int ssl_get_remaining_payload_in_datagram( mbedtls_ssl_context const *ssl
     size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
-    const size_t mfl = mbedtls_ssl_get_max_frag_len( ssl );
+    const size_t mfl = mbedtls_ssl_get_output_max_frag_len( ssl );
 
     if( max_len > mfl )
         max_len = mfl;

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
@@ -3673,36 +3673,51 @@ static int ssl_handshake_init( mbedtls_ssl_context *ssl )
     /* If the buffers are too small - reallocate */
     {
         int modified = 0;
-        if( ssl->in_buf_len < MBEDTLS_SSL_IN_BUFFER_LEN )
+        size_t written_in = 0;
+        size_t written_out = 0;
+        if( ssl->in_buf != NULL )
         {
-            if( resize_buffer( &ssl->in_buf, MBEDTLS_SSL_IN_BUFFER_LEN,
-                               &ssl->in_buf_len ) != 0 )
-            {
-                MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
-            }
-            else
+            written_in = ssl->in_msg - ssl->in_buf;
+            if( ssl->in_buf_len < MBEDTLS_SSL_IN_BUFFER_LEN )
             {
-                MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", MBEDTLS_SSL_IN_BUFFER_LEN ) );
-                modified = 1;
+                if( resize_buffer( &ssl->in_buf, MBEDTLS_SSL_IN_BUFFER_LEN,
+                                   &ssl->in_buf_len ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
+                }
+                else
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", MBEDTLS_SSL_IN_BUFFER_LEN ) );
+                    modified = 1;
+                }
             }
         }
-        if( ssl->out_buf_len < MBEDTLS_SSL_OUT_BUFFER_LEN )
+
+        if( ssl->out_buf != NULL )
         {
-            if( resize_buffer( &ssl->out_buf, MBEDTLS_SSL_OUT_BUFFER_LEN,
-                               &ssl->out_buf_len ) != 0 )
-            {
-                MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
-            }
-            else
+            written_out = ssl->out_msg - ssl->out_buf;
+            if( ssl->out_buf_len < MBEDTLS_SSL_OUT_BUFFER_LEN )
             {
-                MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", MBEDTLS_SSL_OUT_BUFFER_LEN ) );
-                modified = 1;
+                if( resize_buffer( &ssl->out_buf, MBEDTLS_SSL_OUT_BUFFER_LEN,
+                                   &ssl->out_buf_len ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
+                }
+                else
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", MBEDTLS_SSL_OUT_BUFFER_LEN ) );
+                    modified = 1;
+                }
             }
         }
         if( modified )
         {
             /* Update pointers here to avoid doing it twice. */
             mbedtls_ssl_reset_in_out_pointers( ssl );
+            /* Fields below might not be properly updated with record
+            * splitting, so they are manually updated here. */
+            ssl->out_msg = ssl->out_buf + written_out;
+            ssl->in_msg = ssl->in_buf + written_in;
         }
     }
 #endif
@@ -4889,7 +4904,42 @@ const char *mbedtls_ssl_get_version( const mbedtls_ssl_context *ssl )
 }
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
-size_t mbedtls_ssl_get_max_frag_len( const mbedtls_ssl_context *ssl )
+size_t mbedtls_ssl_get_input_max_frag_len( const mbedtls_ssl_context *ssl )
+{
+    size_t max_len = MBEDTLS_SSL_MAX_CONTENT_LEN;
+    size_t read_mfl;
+
+    /* Use the configured MFL for the client if we're past SERVER_HELLO_DONE */
+    if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
+        ssl->state >= MBEDTLS_SSL_SERVER_HELLO_DONE )
+    {
+        return ssl_mfl_code_to_length( ssl->conf->mfl_code );
+    }
+
+    /* Check if a smaller max length was negotiated */
+    if( ssl->session_out != NULL )
+    {
+        read_mfl = ssl_mfl_code_to_length( ssl->session_out->mfl_code );
+        if( read_mfl < max_len )
+        {
+            max_len = read_mfl;
+        }
+    }
+
+    // During a handshake, use the value being negotiated
+    if( ssl->session_negotiate != NULL )
+    {
+        read_mfl = ssl_mfl_code_to_length( ssl->session_negotiate->mfl_code );
+        if( read_mfl < max_len )
+        {
+            max_len = read_mfl;
+        }
+    }
+
+    return( max_len );
+}
+
+size_t mbedtls_ssl_get_output_max_frag_len( const mbedtls_ssl_context *ssl )
 {
     size_t max_len;
 
@@ -4914,6 +4964,13 @@ size_t mbedtls_ssl_get_max_frag_len( const mbedtls_ssl_context *ssl )
 
     return( max_len );
 }
+
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+size_t mbedtls_ssl_get_max_frag_len( const mbedtls_ssl_context *ssl )
+{
+    return mbedtls_ssl_get_output_max_frag_len( ssl );
+}
+#endif /* !MBEDTLS_DEPRECATED_REMOVED */
 #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
 
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
@@ -4946,7 +5003,7 @@ int mbedtls_ssl_get_max_out_record_payload( const mbedtls_ssl_context *ssl )
 #endif
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
-    const size_t mfl = mbedtls_ssl_get_max_frag_len( ssl );
+    const size_t mfl = mbedtls_ssl_get_output_max_frag_len( ssl );
 
     if( max_len > mfl )
         max_len = mfl;
@@ -5892,36 +5949,41 @@ void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
         uint32_t buf_len = mbedtls_ssl_get_input_buflen( ssl );
         size_t written_in = 0;
         size_t written_out = 0;
-        if( ssl->in_buf != NULL &&
-            ssl->in_buf_len > buf_len &&
-            ssl->in_left < buf_len )
+        if( ssl->in_buf != NULL )
         {
             written_in = ssl->in_msg - ssl->in_buf;
-            if( resize_buffer( &ssl->in_buf, buf_len, &ssl->in_buf_len ) != 0 )
-            {
-                MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
-            }
-            else
+            if( ssl->in_buf_len > buf_len && ssl->in_left < buf_len )
             {
-                MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", buf_len ) );
-                modified = 1;
+                written_in = ssl->in_msg - ssl->in_buf;
+                if( resize_buffer( &ssl->in_buf, buf_len, &ssl->in_buf_len ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
+                }
+                else
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", buf_len ) );
+                    modified = 1;
+                }
             }
         }
 
+
         buf_len = mbedtls_ssl_get_output_buflen( ssl );
-        if( ssl->out_buf != NULL &&
-            ssl->out_buf_len > mbedtls_ssl_get_output_buflen( ssl ) &&
-            ssl->out_left < buf_len )
+        if(ssl->out_buf != NULL )
         {
             written_out = ssl->out_msg - ssl->out_buf;
-            if( resize_buffer( &ssl->out_buf, buf_len, &ssl->out_buf_len ) != 0 )
-            {
-                MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
-            }
-            else
+            if( ssl->out_buf_len > mbedtls_ssl_get_output_buflen( ssl ) &&
+                ssl->out_left < buf_len )
             {
-                MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", buf_len ) );
-                modified = 1;
+                if( resize_buffer( &ssl->out_buf, buf_len, &ssl->out_buf_len ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
+                }
+                else
+                {
+                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", buf_len ) );
+                    modified = 1;
+                }
             }
         }
         if( modified )

diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
@@ -2553,8 +2553,10 @@ int main( int argc, char *argv[] )
         mbedtls_printf( "    [ Record expansion is unknown (compression) ]\n" );
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
-    mbedtls_printf( "    [ Maximum fragment length is %u ]\n",
-                    (unsigned int) mbedtls_ssl_get_max_frag_len( &ssl ) );
+    mbedtls_printf( "    [ Maximum input fragment length is %u ]\n",
+                    (unsigned int) mbedtls_ssl_get_input_max_frag_len( &ssl ) );
+    mbedtls_printf( "    [ Maximum output fragment length is %u ]\n",
+                    (unsigned int) mbedtls_ssl_get_output_max_frag_len( &ssl ) );
 #endif
 
 #if defined(MBEDTLS_SSL_ALPN)

diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
@@ -3633,8 +3633,10 @@ int main( int argc, char *argv[] )
         mbedtls_printf( "    [ Record expansion is unknown (compression) ]\n" );
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
-    mbedtls_printf( "    [ Maximum fragment length is %u ]\n",
-                    (unsigned int) mbedtls_ssl_get_max_frag_len( &ssl ) );
+    mbedtls_printf( "    [ Maximum input fragment length is %u ]\n",
+                    (unsigned int) mbedtls_ssl_get_input_max_frag_len( &ssl ) );
+    mbedtls_printf( "    [ Maximum output fragment length is %u ]\n",
+                    (unsigned int) mbedtls_ssl_get_output_max_frag_len( &ssl ) );
 #endif
 
 #if defined(MBEDTLS_SSL_ALPN)