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Limit padded record to max plaintext 

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3374)
This commit is contained in:
Todd Short 2017-05-03 11:24:21 -04:00 committed by Matt Caswell
parent 47f7cf051b
commit 96c9aee2a8
1 changed files with 30 additions and 27 deletions
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57
ssl/record/rec_layer_s3.c
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@ -860,7 +860,7 @@ int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
} }
if (SSL_TREAT_AS_TLS13(s) && s->enc_write_ctx != NULL) { if (SSL_TREAT_AS_TLS13(s) && s->enc_write_ctx != NULL) {
size_t padding = 0; size_t rlen;
if (!WPACKET_put_bytes_u8(thispkt, type)) { if (!WPACKET_put_bytes_u8(thispkt, type)) {
SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR); SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);
@ -869,34 +869,37 @@ int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
SSL3_RECORD_add_length(thiswr, 1); SSL3_RECORD_add_length(thiswr, 1);
/* Add TLS1.3 padding */ /* Add TLS1.3 padding */
if (s->record_padding_cb != NULL) { rlen = SSL3_RECORD_get_length(thiswr);
size_t rlen = SSL3_RECORD_get_length(thiswr); if (rlen < SSL3_RT_MAX_PLAIN_LENGTH) {
size_t padding = 0;
size_t max_padding = SSL3_RT_MAX_PLAIN_LENGTH - rlen;
if (s->record_padding_cb != NULL) {
padding = s->record_padding_cb(s, type, rlen, s->record_padding_arg);
} else if (s->block_padding > 0) {
size_t mask = s->block_padding - 1;
size_t remainder;
padding = s->record_padding_cb(s, type, rlen, s->record_padding_arg); /* optimize for power of 2 */
/* do not allow the record to exceed max plaintext length */ if ((s->block_padding & mask) == 0)
if (padding > (SSL3_RT_MAX_PLAIN_LENGTH - rlen)) remainder = rlen & mask;
padding = SSL3_RT_MAX_PLAIN_LENGTH - rlen; else
} else if (s->block_padding > 0) { remainder = rlen % s->block_padding;
size_t mask = s->block_padding - 1; /* don't want to add a block of padding if we don't have to */
size_t remainder; if (remainder == 0)
padding = 0;
/* optimize for power of 2 */ else
if ((s->block_padding & mask) == 0) padding = s->block_padding - remainder;
remainder = SSL3_RECORD_get_length(thiswr) & mask; }
else if (padding > 0) {
remainder = SSL3_RECORD_get_length(thiswr) % s->block_padding; /* do not allow the record to exceed max plaintext length */
/* don't want to add a block of padding if we don't have to */ if (padding > max_padding)
if (remainder == 0) padding = max_padding;
padding = 0; if (!WPACKET_memset(thispkt, 0, padding)) {
else SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);
padding = s->block_padding - remainder; goto err;
} }
if (padding > 0) { SSL3_RECORD_add_length(thiswr, padding);
if (!WPACKET_memset(thispkt, 0, padding)) {
SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);
goto err;
} }
SSL3_RECORD_add_length(thiswr, padding);
} }
} }