Sanity check EVP_CTRL_AEAD_TLS_AAD

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>

apps/speed.c

@@ -2456,7 +2456,7 @@ static void multiblock_speed(const EVP_CIPHER *evp_cipher)
         print_message(alg_name, 0, mblengths[j]);
         Time_F(START);
         for (count = 0, run = 1; run && count < 0x7fffffff; count++) {
-            unsigned char aad[13];
+            unsigned char aad[EVP_AEAD_TLS1_AAD_LEN];
             EVP_CTRL_TLS1_1_MULTIBLOCK_PARAM mb_param;
             size_t len = mblengths[j];
             int packlen;
@@ -2491,7 +2491,8 @@ static void multiblock_speed(const EVP_CIPHER *evp_cipher)
                 aad[11] = len >> 8;
                 aad[12] = len;
                 pad = EVP_CIPHER_CTX_ctrl(&ctx,
-                                          EVP_CTRL_AEAD_TLS1_AAD, 13, aad);
+                                          EVP_CTRL_AEAD_TLS1_AAD,
+                                          EVP_AEAD_TLS1_AAD_LEN, aad);
                 EVP_Cipher(&ctx, out, inp, len + pad);
             }
         }

crypto/evp/e_aes.c

@@ -1327,7 +1327,7 @@ 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;

crypto/evp/e_aes_cbc_hmac_sha1.c

@@ -845,7 +845,12 @@ 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;
@@ -862,8 +867,6 @@ 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;
 

crypto/evp/e_aes_cbc_hmac_sha256.c

@@ -817,6 +817,11 @@ static int aesni_cbc_hmac_sha256_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg,
             unsigned char *p = ptr;
             unsigned int len = p[arg - 2] << 8 | p[arg - 1];
 
+            if (arg != EVP_AEAD_TLS1_AAD_LEN)
+                return -1;
+
+            len = p[arg - 2] << 8 | p[arg - 1];
+
             if (ctx->encrypt) {
                 key->payload_length = len;
                 if ((key->aux.tls_ver =
@@ -832,8 +837,6 @@ static int aesni_cbc_hmac_sha256_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;
 

crypto/evp/e_rc4_hmac_md5.c

@@ -257,7 +257,12 @@ 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;

include/openssl/evp.h

@@ -426,6 +426,9 @@ struct evp_cipher_st {
 # define         EVP_CTRL_TLS1_1_MULTIBLOCK_DECRYPT      0x1b
 # define         EVP_CTRL_TLS1_1_MULTIBLOCK_MAX_BUFSIZE  0x1c
 
+/* RFC 5246 defines additional data to be 13 bytes in length */
+# define         EVP_AEAD_TLS1_AAD_LEN           13
+
 typedef struct {
     unsigned char *out;
     const unsigned char *inp;

ssl/record/ssl3_record.c

@@ -658,7 +658,7 @@ 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 ? RECORD_LAYER_get_write_sequence(&s->rlayer)
                 : RECORD_LAYER_get_read_sequence(&s->rlayer);
@@ -684,7 +684,10 @@ 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;