ssl/*: revert "remove SSL_RECORD->orig_len" and merge "fix IV".

Revert is appropriate because binary compatibility is not an issue
in 1.1.

ssl/d1_pkt.c

@@ -379,7 +379,7 @@ dtls1_process_record(SSL *s)
 	int enc_err;
 	SSL_SESSION *sess;
 	SSL3_RECORD *rr;
-	unsigned int mac_size, orig_len;
+	unsigned int mac_size;
 	unsigned char md[EVP_MAX_MD_SIZE];
 
 	rr= &(s->s3->rrec);
@@ -410,7 +410,7 @@ dtls1_process_record(SSL *s)
 
 	/* decrypt in place in 'rr->input' */
 	rr->data=rr->input;
-	orig_len=rr->length;
+	rr->orig_len=rr->length;
 
 	enc_err = s->method->ssl3_enc->enc(s,0);
 	/* enc_err is:
@@ -447,10 +447,10 @@ printf("\n");
 		 * 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 ||
+		if (rr->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))
+		     rr->orig_len < mac_size+1))
 			{
 			al=SSL_AD_DECODE_ERROR;
 			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
@@ -465,12 +465,12 @@ printf("\n");
 			 * without leaking the contents of the padding bytes.
 			 * */
 			mac = mac_tmp;
-			ssl3_cbc_copy_mac(mac_tmp, rr, mac_size, orig_len);
+			ssl3_cbc_copy_mac(mac_tmp, rr, mac_size);
 			rr->length -= mac_size;
 			}
 		else
 			{
-			/* In this case there's no padding, so |orig_len|
+			/* In this case there's no padding, so |rec->orig_len|
 			 * equals |rec->length| and we checked that there's
 			 * enough bytes for |mac_size| above. */
 			rr->length -= mac_size;

ssl/s3_cbc.c

@@ -116,9 +116,7 @@ int ssl3_cbc_remove_padding(const SSL* s,
 	good = constant_time_ge(rec->length, padding_length+overhead);
 	/* SSLv3 requires that the padding is minimal. */
 	good &= constant_time_ge(block_size, padding_length+1);
-	padding_length = good & (padding_length+1);
-	rec->length -= padding_length;
-	rec->type |= padding_length<<8;	/* kludge: pass padding length */
+	rec->length -= good & (padding_length+1);
 	return (int)((good & 1) | (~good & -1));
 }
 
@@ -139,31 +137,23 @@ int tls1_cbc_remove_padding(const SSL* s,
 			    unsigned mac_size)
 	{
 	unsigned padding_length, good, to_check, i;
-	const char has_explicit_iv =
-		s->version >= TLS1_1_VERSION || s->version == DTLS1_VERSION;
-	const unsigned overhead = 1 /* padding length byte */ +
-				  mac_size +
-				  (has_explicit_iv ? block_size : 0);
-
-	/* These lengths are all public so we can test them in non-constant
-	 * time. */
-	if (overhead > rec->length)
-		return 0;
-
-	/* We can always safely skip the explicit IV. We check at the beginning
-	 * of this function that the record has at least enough space for the
-	 * IV, MAC and padding length byte. (These can be checked in
-	 * non-constant time because it's all public information.) So, if the
-	 * padding was invalid, then we didn't change |rec->length| and this is
-	 * safe. If the padding was valid then we know that we have at least
-	 * overhead+padding_length bytes of space and so this is still safe
-	 * because overhead accounts for the explicit IV. */
-	if (has_explicit_iv)
+	const unsigned overhead = 1 /* padding length byte */ + mac_size;
+	/* Check if version requires explicit IV */
+	if (s->version >= TLS1_1_VERSION || s->version == DTLS1_VERSION)
 		{
+		/* These lengths are all public so we can test them in
+		 * non-constant time.
+		 */
+		if (overhead + block_size > rec->length)
+			return 0;
+		/* We can now safely skip explicit IV */
 		rec->data += block_size;
 		rec->input += block_size;
 		rec->length -= block_size;
+		rec->orig_len -= block_size;
 		}
+	else if (overhead > rec->length)
+		return 0;
 
 	padding_length = rec->data[rec->length-1];
 
@@ -190,7 +180,7 @@ int tls1_cbc_remove_padding(const SSL* s,
 	if (EVP_CIPHER_flags(s->enc_read_ctx->cipher)&EVP_CIPH_FLAG_AEAD_CIPHER)
 		{
 		/* padding is already verified */
-		rec->length -= padding_length;
+		rec->length -= padding_length + 1;
 		return 1;
 		}
 
@@ -227,9 +217,7 @@ int tls1_cbc_remove_padding(const SSL* s,
 	good <<= sizeof(good)*8-1;
 	good = DUPLICATE_MSB_TO_ALL(good);
 
-	padding_length = good & (padding_length+1);
-	rec->length -= padding_length;
-	rec->type |= padding_length<<8;	/* kludge: pass padding length */
+	rec->length -= good & (padding_length+1);
 
 	return (int)((good & 1) | (~good & -1));
 	}
@@ -256,7 +244,7 @@ int tls1_cbc_remove_padding(const SSL* s,
  */
 void ssl3_cbc_copy_mac(unsigned char* out,
 		       const SSL3_RECORD *rec,
-		       unsigned md_size,unsigned orig_len)
+		       unsigned md_size)
 	{
 #if defined(CBC_MAC_ROTATE_IN_PLACE)
 	unsigned char rotated_mac_buf[EVP_MAX_MD_SIZE*2];
@@ -275,7 +263,7 @@ void ssl3_cbc_copy_mac(unsigned char* out,
 	unsigned div_spoiler;
 	unsigned rotate_offset;
 
-	OPENSSL_assert(orig_len >= md_size);
+	OPENSSL_assert(rec->orig_len >= md_size);
 	OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
 
 #if defined(CBC_MAC_ROTATE_IN_PLACE)
@@ -283,8 +271,8 @@ void ssl3_cbc_copy_mac(unsigned char* out,
 #endif
 
 	/* This information is public so it's safe to branch based on it. */
-	if (orig_len > md_size + 255 + 1)
-		scan_start = orig_len - (md_size + 255 + 1);
+	if (rec->orig_len > md_size + 255 + 1)
+		scan_start = rec->orig_len - (md_size + 255 + 1);
 	/* div_spoiler contains a multiple of md_size that is used to cause the
 	 * modulo operation to be constant time. Without this, the time varies
 	 * based on the amount of padding when running on Intel chips at least.
@@ -297,9 +285,9 @@ void ssl3_cbc_copy_mac(unsigned char* out,
 	rotate_offset = (div_spoiler + mac_start - scan_start) % md_size;
 
 	memset(rotated_mac, 0, md_size);
-	for (i = scan_start; i < orig_len;)
+	for (i = scan_start; i < rec->orig_len;)
 		{
-		for (j = 0; j < md_size && i < orig_len; i++, j++)
+		for (j = 0; j < md_size && i < rec->orig_len; i++, j++)
 			{
 			unsigned char mac_started = constant_time_ge(i, mac_start);
 			unsigned char mac_ended = constant_time_ge(i, mac_end);

ssl/s3_enc.c

@@ -730,7 +730,7 @@ int n_ssl3_mac(SSL *ssl, unsigned char *md, int send)
 	EVP_MD_CTX md_ctx;
 	const EVP_MD_CTX *hash;
 	unsigned char *p,rec_char;
-	size_t md_size, orig_len;
+	size_t md_size;
 	int npad;
 	int t;
 
@@ -755,10 +755,6 @@ int n_ssl3_mac(SSL *ssl, unsigned char *md, int send)
 	md_size=t;
 	npad=(48/md_size)*md_size;
 
-	/* kludge: ssl3_cbc_remove_padding passes padding length in rec->type */
-	orig_len = rec->length+md_size+((unsigned int)rec->type>>8);
-	rec->type &= 0xff;
-
 	if (!send &&
 	    EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
 	    ssl3_cbc_record_digest_supported(hash))
@@ -790,7 +786,7 @@ int n_ssl3_mac(SSL *ssl, unsigned char *md, int send)
 			hash,
 			md, &md_size,
 			header, rec->input,
-			rec->length + md_size, orig_len,
+			rec->length + md_size, rec->orig_len,
 			mac_sec, md_size,
 			1 /* is SSLv3 */);
 		}

ssl/s3_pkt.c

@@ -290,7 +290,7 @@ static int ssl3_get_record(SSL *s)
 	unsigned char *p;
 	unsigned char md[EVP_MAX_MD_SIZE];
 	short version;
-	unsigned mac_size, orig_len;
+	unsigned mac_size;
 	size_t extra;
 
 	rr= &(s->s3->rrec);
@@ -400,7 +400,7 @@ fprintf(stderr, "Record type=%d, Length=%d\n", rr->type, rr->length);
 
 	/* decrypt in place in 'rr->input' */
 	rr->data=rr->input;
-	orig_len=rr->length;
+	rr->orig_len=rr->length;
 
 	enc_err = s->method->ssl3_enc->enc(s,0);
 	/* enc_err is:
@@ -436,10 +436,10 @@ printf("\n");
 		 * 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 ||
+		if (rr->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))
+		     rr->orig_len < mac_size+1))
 			{
 			al=SSL_AD_DECODE_ERROR;
 			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
@@ -454,12 +454,12 @@ printf("\n");
 			 * without leaking the contents of the padding bytes.
 			 * */
 			mac = mac_tmp;
-			ssl3_cbc_copy_mac(mac_tmp, rr, mac_size, orig_len);
+			ssl3_cbc_copy_mac(mac_tmp, rr, mac_size);
 			rr->length -= mac_size;
 			}
 		else
 			{
-			/* In this case there's no padding, so |orig_len|
+			/* In this case there's no padding, so |rec->orig_len|
 			 * equals |rec->length| and we checked that there's
 			 * enough bytes for |mac_size| above. */
 			rr->length -= mac_size;

ssl/ssl3.h

@@ -366,6 +366,10 @@ typedef struct ssl3_record_st
 	{
 /*r */	int type;               /* type of record */
 /*rw*/	unsigned int length;    /* How many bytes available */
+/*rw*/	unsigned int orig_len;  /* How many bytes were available before padding
+				   was removed? This is used to implement the
+				   MAC check in constant time for CBC records.
+				 */
 /*r */	unsigned int off;       /* read/write offset into 'buf' */
 /*rw*/	unsigned char *data;    /* pointer to the record data */
 /*rw*/	unsigned char *input;   /* where the decode bytes are */

ssl/ssl_locl.h

@@ -1275,7 +1275,7 @@ int ssl_parse_serverhello_use_srtp_ext(SSL *s, unsigned char *d, int len,int *al
 /* s3_cbc.c */
 void ssl3_cbc_copy_mac(unsigned char* out,
 		       const SSL3_RECORD *rec,
-		       unsigned md_size,unsigned orig_len);
+		       unsigned md_size);
 int ssl3_cbc_remove_padding(const SSL* s,
 			    SSL3_RECORD *rec,
 			    unsigned block_size,

ssl/t1_enc.c

@@ -973,7 +973,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
 	SSL3_RECORD *rec;
 	unsigned char *seq;
 	EVP_MD_CTX *hash;
-	size_t md_size, orig_len;
+	size_t md_size;
 	int i;
 	EVP_MD_CTX hmac, *mac_ctx;
 	unsigned char header[13];
@@ -1020,10 +1020,6 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
 	else
 		memcpy(header, seq, 8);
 
-	/* kludge: tls1_cbc_remove_padding passes padding length in rec->type */
-	orig_len = rec->length+md_size+((unsigned int)rec->type>>8);
-	rec->type &= 0xff;
-
 	header[8]=rec->type;
 	header[9]=(unsigned char)(ssl->version>>8);
 	header[10]=(unsigned char)(ssl->version);
@@ -1042,7 +1038,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
 			mac_ctx,
 			md, &md_size,
 			header, rec->input,
-			rec->length + md_size, orig_len,
+			rec->length + md_size, rec->orig_len,
 			ssl->s3->read_mac_secret,
 			ssl->s3->read_mac_secret_size,
 			0 /* not SSLv3 */);
@@ -1058,7 +1054,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
 			tls_fips_digest_extra(
 	    				ssl->enc_read_ctx,
 					mac_ctx, rec->input,
-					rec->length, orig_len);
+					rec->length, rec->orig_len);
 #endif
 		}