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[mbedTLS] Integrate TLS handshake defragmentation PR

Upstream PR GH-9981
This commit is contained in:
Fabio Alessandrelli
2025-02-24 13:40:17 +01:00
parent 0e3dbba6a5
commit af0bc17c4f
7 changed files with 509 additions and 49 deletions

View File

@@ -25,6 +25,7 @@
#include "constant_time_internal.h"
#include "mbedtls/constant_time.h"
#include <limits.h>
#include <string.h>
#if defined(MBEDTLS_USE_PSA_CRYPTO)
@@ -3220,13 +3221,17 @@ static uint32_t ssl_get_hs_total_len(mbedtls_ssl_context const *ssl)
int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
{
if (ssl->in_msglen < mbedtls_ssl_hs_hdr_len(ssl)) {
/* First handshake fragment must at least include the header. */
if (ssl->in_msglen < mbedtls_ssl_hs_hdr_len(ssl) && ssl->in_hslen == 0) {
MBEDTLS_SSL_DEBUG_MSG(1, ("handshake message too short: %" MBEDTLS_PRINTF_SIZET,
ssl->in_msglen));
return MBEDTLS_ERR_SSL_INVALID_RECORD;
}
ssl->in_hslen = mbedtls_ssl_hs_hdr_len(ssl) + ssl_get_hs_total_len(ssl);
if (ssl->in_hslen == 0) {
ssl->in_hslen = mbedtls_ssl_hs_hdr_len(ssl) + ssl_get_hs_total_len(ssl);
ssl->badmac_seen_or_in_hsfraglen = 0;
}
MBEDTLS_SSL_DEBUG_MSG(3, ("handshake message: msglen ="
" %" MBEDTLS_PRINTF_SIZET ", type = %u, hslen = %"
@@ -3292,10 +3297,67 @@ int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
}
} else
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/* With TLS we don't handle fragmentation (for now) */
if (ssl->in_msglen < ssl->in_hslen) {
MBEDTLS_SSL_DEBUG_MSG(1, ("TLS handshake fragmentation not supported"));
return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
if (ssl->badmac_seen_or_in_hsfraglen <= ssl->in_hslen) {
int ret;
const size_t hs_remain = ssl->in_hslen - ssl->badmac_seen_or_in_hsfraglen;
MBEDTLS_SSL_DEBUG_MSG(3,
("handshake fragment: %u .. %"
MBEDTLS_PRINTF_SIZET " of %"
MBEDTLS_PRINTF_SIZET " msglen %" MBEDTLS_PRINTF_SIZET,
ssl->badmac_seen_or_in_hsfraglen,
(size_t) ssl->badmac_seen_or_in_hsfraglen +
(hs_remain <= ssl->in_msglen ? hs_remain : ssl->in_msglen),
ssl->in_hslen, ssl->in_msglen));
if (ssl->in_msglen < hs_remain) {
/* ssl->in_msglen is a 25-bit value since it is the sum of the
* header length plus the payload length, the header length is 4
* and the payload length was received on the wire encoded as
* 3 octets. We don't support 16-bit platforms; more specifically,
* we assume that both unsigned and size_t are at least 32 bits.
* Therefore there is no possible integer overflow here.
*/
ssl->badmac_seen_or_in_hsfraglen += (unsigned) ssl->in_msglen;
ssl->in_hdr = ssl->in_msg + ssl->in_msglen;
ssl->in_msglen = 0;
mbedtls_ssl_update_in_pointers(ssl);
return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
}
if (ssl->badmac_seen_or_in_hsfraglen > 0) {
/*
* At in_first_hdr we have a sequence of records that cover the next handshake
* record, each with its own record header that we need to remove.
* Note that the reassembled record size may not equal the size of the message,
* there may be more messages after it, complete or partial.
*/
unsigned char *in_first_hdr = ssl->in_buf + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
unsigned char *p = in_first_hdr, *q = NULL;
size_t merged_rec_len = 0;
do {
mbedtls_record rec;
ret = ssl_parse_record_header(ssl, p, mbedtls_ssl_in_hdr_len(ssl), &rec);
if (ret != 0) {
return ret;
}
merged_rec_len += rec.data_len;
p = rec.buf + rec.buf_len;
if (q != NULL) {
memmove(q, rec.buf + rec.data_offset, rec.data_len);
q += rec.data_len;
} else {
q = p;
}
} while (merged_rec_len < ssl->in_hslen);
ssl->in_hdr = in_first_hdr;
mbedtls_ssl_update_in_pointers(ssl);
ssl->in_msglen = merged_rec_len;
/* Adjust message length. */
MBEDTLS_PUT_UINT16_BE(merged_rec_len, ssl->in_len, 0);
ssl->badmac_seen_or_in_hsfraglen = 0;
MBEDTLS_SSL_DEBUG_BUF(4, "reassembled record",
ssl->in_hdr, mbedtls_ssl_in_hdr_len(ssl) + merged_rec_len);
}
} else {
return MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
}
return 0;
@@ -4640,6 +4702,16 @@ static int ssl_consume_current_message(mbedtls_ssl_context *ssl)
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
if (ssl->badmac_seen_or_in_hsfraglen != 0) {
/* Not all handshake fragments have arrived, do not consume. */
MBEDTLS_SSL_DEBUG_MSG(3,
("waiting for more fragments (%u of %"
MBEDTLS_PRINTF_SIZET ", %" MBEDTLS_PRINTF_SIZET " left)",
ssl->badmac_seen_or_in_hsfraglen, ssl->in_hslen,
ssl->in_hslen - ssl->badmac_seen_or_in_hsfraglen));
return 0;
}
/*
* Get next Handshake message in the current record
*/
@@ -4665,6 +4737,7 @@ static int ssl_consume_current_message(mbedtls_ssl_context *ssl)
ssl->in_msglen -= ssl->in_hslen;
memmove(ssl->in_msg, ssl->in_msg + ssl->in_hslen,
ssl->in_msglen);
MBEDTLS_PUT_UINT16_BE(ssl->in_msglen, ssl->in_len, 0);
MBEDTLS_SSL_DEBUG_BUF(4, "remaining content in record",
ssl->in_msg, ssl->in_msglen);
@@ -4967,10 +5040,12 @@ static int ssl_get_next_record(mbedtls_ssl_context *ssl)
return ret;
}
if (ssl->conf->badmac_limit != 0 &&
++ssl->badmac_seen >= ssl->conf->badmac_limit) {
MBEDTLS_SSL_DEBUG_MSG(1, ("too many records with bad MAC"));
return MBEDTLS_ERR_SSL_INVALID_MAC;
if (ssl->conf->badmac_limit != 0) {
++ssl->badmac_seen_or_in_hsfraglen;
if (ssl->badmac_seen_or_in_hsfraglen >= ssl->conf->badmac_limit) {
MBEDTLS_SSL_DEBUG_MSG(1, ("too many records with bad MAC"));
return MBEDTLS_ERR_SSL_INVALID_MAC;
}
}
/* As above, invalid records cause
@@ -5345,7 +5420,7 @@ void mbedtls_ssl_update_in_pointers(mbedtls_ssl_context *ssl)
} else
#endif
{
ssl->in_ctr = ssl->in_hdr - MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
ssl->in_ctr = ssl->in_buf;
ssl->in_len = ssl->in_hdr + 3;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
ssl->in_cid = ssl->in_len;
@@ -5361,24 +5436,35 @@ void mbedtls_ssl_update_in_pointers(mbedtls_ssl_context *ssl)
* Setup an SSL context
*/
void mbedtls_ssl_reset_in_out_pointers(mbedtls_ssl_context *ssl)
void mbedtls_ssl_reset_in_pointers(mbedtls_ssl_context *ssl)
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
ssl->in_hdr = ssl->in_buf;
} else
#endif /* MBEDTLS_SSL_PROTO_DTLS */
{
ssl->in_hdr = ssl->in_buf + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
}
/* Derive other internal pointers. */
mbedtls_ssl_update_in_pointers(ssl);
}
void mbedtls_ssl_reset_out_pointers(mbedtls_ssl_context *ssl)
{
/* Set the incoming and outgoing record pointers. */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
ssl->out_hdr = ssl->out_buf;
ssl->in_hdr = ssl->in_buf;
} else
#endif /* MBEDTLS_SSL_PROTO_DTLS */
{
ssl->out_ctr = ssl->out_buf;
ssl->out_hdr = ssl->out_buf + 8;
ssl->in_hdr = ssl->in_buf + 8;
ssl->out_hdr = ssl->out_buf + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
}
/* Derive other internal pointers. */
mbedtls_ssl_update_out_pointers(ssl, NULL /* no transform enabled */);
mbedtls_ssl_update_in_pointers(ssl);
}
/*