unsigned char *p;
unsigned char md[EVP_MAX_MD_SIZE];
short version;
- unsigned int mac_size;
- int clear=0;
+ unsigned mac_size, orig_len;
size_t extra;
- int decryption_failed_or_bad_record_mac = 0;
- unsigned char *mac = NULL;
rr= &(s->s3->rrec);
sess=s->session;
if (version != s->version)
{
SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_WRONG_VERSION_NUMBER);
- /* Send back error using their
- * version number :-) */
- s->version=version;
+ if ((s->version & 0xFF00) == (version & 0xFF00))
+ /* Send back error using their minor version number :-) */
+ s->version = (unsigned short)version;
al=SSL_AD_PROTOCOL_VERSION;
goto f_err;
}
rr->data=rr->input;
enc_err = s->method->ssl3_enc->enc(s,0);
- if (enc_err <= 0)
+ /* enc_err is:
+ * 0: (in non-constant time) if the record is publically invalid.
+ * 1: if the padding is valid
+ * -1: if the padding is invalid */
+ if (enc_err == 0)
{
- if (enc_err == 0)
- /* SSLerr() and ssl3_send_alert() have been called */
- goto err;
-
- /* Otherwise enc_err == -1, which indicates bad padding
- * (rec->length has not been changed in this case).
- * To minimize information leaked via timing, we will perform
- * the MAC computation anyway. */
- decryption_failed_or_bad_record_mac = 1;
+ al=SSL_AD_DECRYPTION_FAILED;
+ SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_BLOCK_CIPHER_PAD_IS_WRONG);
+ goto f_err;
}
#ifdef TLS_DEBUG
#endif
/* r->length is now the compressed data plus mac */
- if ( (sess == NULL) ||
- (s->enc_read_ctx == NULL) ||
- (s->read_hash == NULL))
- clear=1;
-
- if (!clear)
+ if ((sess != NULL) &&
+ (s->enc_read_ctx != NULL) &&
+ (s->read_hash != NULL))
{
+ /* s->read_hash != NULL => mac_size != -1 */
+ unsigned char *mac = NULL;
+ unsigned char mac_tmp[EVP_MAX_MD_SIZE];
mac_size=EVP_MD_size(s->read_hash);
+ OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);
- if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+extra+mac_size)
+ /* kludge: *_cbc_remove_padding passes padding length in rr->type */
+ orig_len = rr->length+((unsigned int)rr->type>>8);
+
+ /* orig_len is the length of the record before any padding was
+ * removed. This is public information, as is the MAC in use,
+ * therefore we can safely process the record in a different
+ * amount of time if it's too short to possibly contain a MAC.
+ */
+ if (orig_len < mac_size ||
+ /* CBC records must have a padding length byte too. */
+ (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
+ orig_len < mac_size+1))
{
-#if 0 /* OK only for stream ciphers (then rr->length is visible from ciphertext anyway) */
- al=SSL_AD_RECORD_OVERFLOW;
- SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_PRE_MAC_LENGTH_TOO_LONG);
+ al=SSL_AD_DECODE_ERROR;
+ SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
goto f_err;
-#else
- decryption_failed_or_bad_record_mac = 1;
-#endif
}
- /* check the MAC for rr->input (it's in mac_size bytes at the tail) */
- if (rr->length >= mac_size)
+
+ if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE)
{
+ /* We update the length so that the TLS header bytes
+ * can be constructed correctly but we need to extract
+ * the MAC in constant time from within the record,
+ * without leaking the contents of the padding bytes.
+ * */
+ mac = mac_tmp;
+ ssl3_cbc_copy_mac(mac_tmp, rr, mac_size, orig_len);
rr->length -= mac_size;
- mac = &rr->data[rr->length];
}
else
{
- /* record (minus padding) is too short to contain a MAC */
-#if 0 /* OK only for stream ciphers */
- al=SSL_AD_DECODE_ERROR;
- SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
- goto f_err;
-#else
- decryption_failed_or_bad_record_mac = 1;
- rr->length = 0;
-#endif
- }
- i=s->method->ssl3_enc->mac(s,md,0);
- if (mac == NULL || memcmp(md, mac, mac_size) != 0)
- {
- decryption_failed_or_bad_record_mac = 1;
+ /* In this case there's no padding, so |orig_len|
+ * equals |rec->length| and we checked that there's
+ * enough bytes for |mac_size| above. */
+ rr->length -= mac_size;
+ mac = &rr->data[rr->length];
}
+
+ i=s->method->ssl3_enc->mac(s,md,0 /* not send */);
+ if (i < 0 || mac == NULL || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
+ enc_err = -1;
+ if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+extra+mac_size)
+ enc_err = -1;
}
- if (decryption_failed_or_bad_record_mac)
+ if (enc_err < 0)
{
/* A separate 'decryption_failed' alert was introduced with TLS 1.0,
* SSL 3.0 only has 'bad_record_mac'. But unless a decryption
int ssl3_write_bytes(SSL *s, int type, const void *buf_, int len)
{
const unsigned char *buf=buf_;
- unsigned int tot,n,nw;
- int i;
+ unsigned int n,nw;
+ int i,tot;
s->rwstate=SSL_NOTHING;
+ OPENSSL_assert(s->s3->wnum < INT_MAX);
tot=s->s3->wnum;
s->s3->wnum=0;
}
}
+ /* ensure that if we end up with a smaller value of data to write
+ * out than the the original len from a write which didn't complete
+ * for non-blocking I/O and also somehow ended up avoiding
+ * the check for this in ssl3_write_pending/SSL_R_BAD_WRITE_RETRY as
+ * it must never be possible to end up with (len-tot) as a large
+ * number that will then promptly send beyond the end of the users
+ * buffer ... so we trap and report the error in a way the user
+ * will notice
+ */
+ if (len < tot)
+ {
+ SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_BAD_LENGTH);
+ return(-1);
+ }
+
+
n=(len-tot);
for (;;)
{
projects / oweals / openssl.git / blobdiff