commit acadb0a8c99e2ad6faad8db6318440232034b927
author Hanno Becker <hanno.becker@arm.com> Wed May 08 18:15:21 2019 +0100
committer Hanno Becker <hanno.becker@arm.com> Mon May 20 14:55:59 2019 +0100
tree fd81867f879102dcdbdf4554acd3f16b4d6b2e63
parent 99abf51056d34515f91c8f27a63f234a6c9ed128

Add length of CID to additional data used for record protection

Quoting the CID draft 04:

   -  Block Ciphers:

       MAC(MAC_write_key, seq_num +
           tls12_cid +                     // New input
           DTLSPlaintext.version +
           cid +                           // New input
           cid_length +                    // New input
           length_of_DTLSInnerPlaintext +  // New input
           DTLSInnerPlaintext.content +    // New input
           DTLSInnerPlaintext.real_type +  // New input
           DTLSInnerPlaintext.zeros        // New input
       )

And similar for AEAD and Encrypt-then-MAC.

library/ssl_tls.c

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 24cd580..6ad6f08 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1628,7 +1628,7 @@
 #endif /* MBEDTLS_SSL_CID */
 
 /* `add_data` must have size 13 Bytes if the CID extension is disabled,
- * and 13 + CID-length Bytes if the CID extension is enabled. */
+ * and 13 + 1 + CID-length Bytes if the CID extension is enabled. */
 static void ssl_extract_add_data_from_record( unsigned char* add_data,
                                               size_t *add_data_len,
                                               mbedtls_record *rec )
@@ -1655,9 +1655,10 @@
 
 #if defined(MBEDTLS_SSL_CID)
     memcpy( add_data + 11, rec->cid, rec->cid_len );
-    add_data[11 + rec->cid_len + 0] = ( rec->data_len >> 8 ) & 0xFF;
-    add_data[11 + rec->cid_len + 1] = ( rec->data_len >> 0 ) & 0xFF;
-    *add_data_len = 13 + rec->cid_len;
+    add_data[11 + rec->cid_len + 0] = rec->cid_len;
+    add_data[11 + rec->cid_len + 1] = ( rec->data_len >> 8 ) & 0xFF;
+    add_data[11 + rec->cid_len + 2] = ( rec->data_len >> 0 ) & 0xFF;
+    *add_data_len = 13 + 1 + rec->cid_len;
 #else /* MBEDTLS_SSL_CID */
     add_data[11 + 0] = ( rec->data_len >> 8 ) & 0xFF;
     add_data[11 + 1] = ( rec->data_len >> 0 ) & 0xFF;
@@ -1674,7 +1675,7 @@
     mbedtls_cipher_mode_t mode;
     int auth_done = 0;
     unsigned char * data;
-    unsigned char add_data[13 + MBEDTLS_SSL_CID_LEN_MAX ];
+    unsigned char add_data[13 + 1 + MBEDTLS_SSL_CID_LEN_MAX ];
     size_t add_data_len;
     size_t post_avail;
 
@@ -2114,7 +2115,7 @@
     size_t padlen = 0, correct = 1;
 #endif
     unsigned char* data;
-    unsigned char add_data[13 + MBEDTLS_SSL_CID_LEN_MAX ];
+    unsigned char add_data[13 + 1 + MBEDTLS_SSL_CID_LEN_MAX ];
     size_t add_data_len;
 
 #if !defined(MBEDTLS_DEBUG_C)