Commit 96c9aee2 authored by Todd Short's avatar Todd Short Committed by Matt Caswell
Browse files

Limit padded record to max plaintext 



Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
Reviewed-by: default avatarMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3374)
parent 47f7cf05

ssl/record/rec_layer_s3.c

+31 −28
Original line number Original line Diff line number Diff line
@@ -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);
@@ -869,22 +869,21 @@ 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 */

            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) {

                if (s->record_padding_cb != NULL) {

                size_t rlen = SSL3_RECORD_get_length(thiswr);



                    padding = s->record_padding_cb(s, type, rlen, s->record_padding_arg);

                    padding = s->record_padding_cb(s, type, rlen, s->record_padding_arg);

                /* do not allow the record to exceed max plaintext length */

                if (padding > (SSL3_RT_MAX_PLAIN_LENGTH - rlen))

                    padding = SSL3_RT_MAX_PLAIN_LENGTH - rlen;

                } else if (s->block_padding > 0) {

                } else if (s->block_padding > 0) {

                    size_t mask = s->block_padding - 1;

                    size_t mask = s->block_padding - 1;

                    size_t remainder;

                    size_t remainder;





                    /* optimize for power of 2 */

                    /* optimize for power of 2 */

                    if ((s->block_padding & mask) == 0)

                    if ((s->block_padding & mask) == 0)

                    remainder = SSL3_RECORD_get_length(thiswr) & mask;

                        remainder = rlen & mask;

                    else

                    else

                    remainder = SSL3_RECORD_get_length(thiswr) % s->block_padding;

                        remainder = rlen % s->block_padding;

                    /* don't want to add a block of padding if we don't have to */

                    /* don't want to add a block of padding if we don't have to */

                    if (remainder == 0)

                    if (remainder == 0)

                        padding = 0;

                        padding = 0;
@@ -892,6 +891,9 @@ int do_ssl3_write(SSL *s, int type, const unsigned char *buf, 
                        padding = s->block_padding - remainder;

                        padding = s->block_padding - remainder;

                }

                }

                if (padding > 0) {

                if (padding > 0) {

                    /* do not allow the record to exceed max plaintext length */

                    if (padding > max_padding)

                        padding = max_padding;

                    if (!WPACKET_memset(thispkt, 0, padding)) {

                    if (!WPACKET_memset(thispkt, 0, padding)) {

                        SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);

                        SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);

                        goto err;

                        goto err;
@@ -899,6 +901,7 @@ int do_ssl3_write(SSL *s, int type, const unsigned char *buf, 
                    SSL3_RECORD_add_length(thiswr, padding);

                    SSL3_RECORD_add_length(thiswr, padding);

                }

                }

            }

            }

        }





        /*

        /*

         * we should still have the output to thiswr->data and the input from

         * we should still have the output to thiswr->data and the input from