Sanity check EVP_CTRL_AEAD_TLS_AAD
authorMatt Caswell <matt@openssl.org>
Mon, 27 Apr 2015 10:07:06 +0000 (11:07 +0100)
committerMatt Caswell <matt@openssl.org>
Thu, 30 Apr 2015 22:26:06 +0000 (23:26 +0100)
The various implementations of EVP_CTRL_AEAD_TLS_AAD expect a buffer of at
least 13 bytes long. Add sanity checks to ensure that the length is at
least that. Also add a new constant (EVP_AEAD_TLS1_AAD_LEN) to evp.h to
represent this length. Thanks to Kevin Wojtysiak (Int3 Solutions) and
Paramjot Oberoi (Int3 Solutions) for reporting this issue.

Reviewed-by: Andy Polyakov <appro@openssl.org>
(cherry picked from commit c8269881093324b881b81472be037055571f73f3)

Conflicts:
ssl/record/ssl3_record.c

Conflicts:
apps/speed.c
crypto/evp/e_aes_cbc_hmac_sha256.c
crypto/evp/evp.h

crypto/evp/e_aes.c
crypto/evp/e_aes_cbc_hmac_sha1.c
crypto/evp/e_rc4_hmac_md5.c
crypto/evp/evp.h
ssl/t1_enc.c

index 245c18a..bde4804 100644 (file)
@@ -753,7 +753,7 @@ static int aes_gcm_ctrl(EVP_CIPHER_CTX *c, int type, int arg, void *ptr)
 
     case EVP_CTRL_AEAD_TLS1_AAD:
         /* Save the AAD for later use */
-        if (arg != 13)
+        if (arg != EVP_AEAD_TLS1_AAD_LEN)
             return 0;
         memcpy(c->buf, ptr, arg);
         gctx->tls_aad_len = arg;
index 3f8a5ae..d1f5928 100644 (file)
@@ -503,7 +503,12 @@ static int aesni_cbc_hmac_sha1_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg,
     case EVP_CTRL_AEAD_TLS1_AAD:
         {
             unsigned char *p = ptr;
-            unsigned int len = p[arg - 2] << 8 | p[arg - 1];
+            unsigned int len;
+
+            if (arg != EVP_AEAD_TLS1_AAD_LEN)
+                return -1;
+            len = p[arg - 2] << 8 | p[arg - 1];
 
             if (ctx->encrypt) {
                 key->payload_length = len;
@@ -520,8 +525,6 @@ static int aesni_cbc_hmac_sha1_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg,
                                AES_BLOCK_SIZE) & -AES_BLOCK_SIZE)
                              - len);
             } else {
-                if (arg > 13)
-                    arg = 13;
                 memcpy(key->aux.tls_aad, ptr, arg);
                 key->payload_length = arg;
 
index 80735d3..e6b0cdf 100644 (file)
@@ -258,7 +258,12 @@ static int rc4_hmac_md5_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg,
     case EVP_CTRL_AEAD_TLS1_AAD:
         {
             unsigned char *p = ptr;
-            unsigned int len = p[arg - 2] << 8 | p[arg - 1];
+            unsigned int len;
+
+            if (arg != EVP_AEAD_TLS1_AAD_LEN)
+                return -1;
+
+            len = p[arg - 2] << 8 | p[arg - 1];
 
             if (!ctx->encrypt) {
                 len -= MD5_DIGEST_LENGTH;
index b00997b..01bdeeb 100644 (file)
@@ -409,6 +409,9 @@ struct evp_cipher_st {
 /* Set the GCM invocation field, decrypt only */
 # define         EVP_CTRL_GCM_SET_IV_INV         0x18
 
+/* RFC 5246 defines additional data to be 13 bytes in length */
+# define         EVP_AEAD_TLS1_AAD_LEN           13
+
 /* GCM TLS constants */
 /* Length of fixed part of IV derived from PRF */
 # define EVP_GCM_TLS_FIXED_IV_LEN                        4
index 2736238..8f45294 100644 (file)
@@ -785,7 +785,7 @@ int tls1_enc(SSL *s, int send)
         bs = EVP_CIPHER_block_size(ds->cipher);
 
         if (EVP_CIPHER_flags(ds->cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) {
-            unsigned char buf[13], *seq;
+            unsigned char buf[EVP_AEAD_TLS1_AAD_LEN], *seq;
 
             seq = send ? s->s3->write_sequence : s->s3->read_sequence;
 
@@ -809,7 +809,10 @@ int tls1_enc(SSL *s, int send)
             buf[10] = (unsigned char)(s->version);
             buf[11] = rec->length >> 8;
             buf[12] = rec->length & 0xff;
-            pad = EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_AEAD_TLS1_AAD, 13, buf);
+            pad = EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_AEAD_TLS1_AAD,
+                                      EVP_AEAD_TLS1_AAD_LEN, buf);
+            if (pad <= 0)
+                return -1;
             if (send) {
                 l += pad;
                 rec->length += pad;