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Defragment incoming TLS handshake messages

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Signed-off-by: Deomid rojer Ryabkov <rojer@rojer.me>
This commit is contained in:
Deomid rojer Ryabkov 2024-03-10 02:11:03 +00:00
parent e457bf1c62
commit ac2cf1f26c
5 changed files with 113 additions and 15 deletions
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2
ChangeLog.d/tls-hs-defrag-in.txt Normal file
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@ -0,0 +1,2 @@
Change
* Defragment incoming TLS handshake messages.

2
include/mbedtls/ssl.h
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@ -1808,6 +1808,8 @@ struct mbedtls_ssl_context {
size_t MBEDTLS_PRIVATE(in_hslen); /*!< current handshake message length,
including the handshake header */
unsigned char *MBEDTLS_PRIVATE(in_hshdr); /*!< original handshake header start */
size_t MBEDTLS_PRIVATE(in_hsfraglen); /*!< accumulated hs fragments length */
int MBEDTLS_PRIVATE(nb_zero); /*!< # of 0-length encrypted messages */
int MBEDTLS_PRIVATE(keep_current_message); /*!< drop or reuse current message

8
library/ssl_misc.h
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@ -1829,7 +1829,13 @@ void mbedtls_ssl_set_timer(mbedtls_ssl_context *ssl, uint32_t millisecs);
MBEDTLS_CHECK_RETURN_CRITICAL
int mbedtls_ssl_check_timer(mbedtls_ssl_context *ssl);
void mbedtls_ssl_reset_in_out_pointers(mbedtls_ssl_context *ssl);
void mbedtls_ssl_reset_in_pointers(mbedtls_ssl_context *ssl);
void mbedtls_ssl_reset_out_pointers(mbedtls_ssl_context *ssl);
static inline void mbedtls_ssl_reset_in_out_pointers(mbedtls_ssl_context *ssl)
{
mbedtls_ssl_reset_in_pointers(ssl);
mbedtls_ssl_reset_out_pointers(ssl);
}
void mbedtls_ssl_update_out_pointers(mbedtls_ssl_context *ssl,
mbedtls_ssl_transform *transform);
void mbedtls_ssl_update_in_pointers(mbedtls_ssl_context *ssl);

99
library/ssl_msg.c
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@ -3225,7 +3225,11 @@ int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
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->in_hsfraglen = 0;
ssl->in_hshdr = ssl->in_hdr;
}
MBEDTLS_SSL_DEBUG_MSG(3, ("handshake message: msglen ="
" %" MBEDTLS_PRINTF_SIZET ", type = %u, hslen = %"
@ -3291,10 +3295,59 @@ 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;
{
int ret;
const size_t hs_remain = ssl->in_hslen - ssl->in_hsfraglen;
const size_t msg_hslen = (hs_remain <= ssl->in_msglen ? hs_remain : ssl->in_msglen);
MBEDTLS_SSL_DEBUG_MSG(3,
("handshake fragment: %" MBEDTLS_PRINTF_SIZET " .. %"
MBEDTLS_PRINTF_SIZET " of %"
MBEDTLS_PRINTF_SIZET " msglen %" MBEDTLS_PRINTF_SIZET,
ssl->in_hsfraglen, ssl->in_hsfraglen + msg_hslen,
ssl->in_hslen, ssl->in_msglen));
(void) msg_hslen;
if (ssl->in_msglen < hs_remain) {
ssl->in_hsfraglen += 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->in_hshdr != ssl->in_hdr) {
/*
* At ssl->in_hshdr 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 maybe bytes from the next message following it.
*/
size_t merged_rec_len = 0;
unsigned char *p = ssl->in_hshdr, *q = NULL;
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 = ssl->in_hshdr;
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->in_hsfraglen = 0;
ssl->in_hshdr = NULL;
MBEDTLS_SSL_DEBUG_BUF(4, "reassembled record",
ssl->in_hdr, mbedtls_ssl_in_hdr_len(ssl) + merged_rec_len);
}
}
return 0;
@ -4639,6 +4692,16 @@ static int ssl_consume_current_message(mbedtls_ssl_context *ssl)
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
if (ssl->in_hsfraglen != 0) {
/* Not all handshake fragments have arrived, do not consume. */
MBEDTLS_SSL_DEBUG_MSG(3,
("waiting for more fragments (%" MBEDTLS_PRINTF_SIZET " of %"
MBEDTLS_PRINTF_SIZET ", %" MBEDTLS_PRINTF_SIZET " left)",
ssl->in_hsfraglen, ssl->in_hslen,
ssl->in_hslen - ssl->in_hsfraglen));
return 0;
}
/*
* Get next Handshake message in the current record
*/
@ -4664,6 +4727,7 @@ 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);
@ -5338,7 +5402,7 @@ 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;
@ -5354,24 +5418,35 @@ 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
{
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);
}
/*

17
library/ssl_tls.c
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@ -343,12 +343,17 @@ static void handle_buffer_resizing(mbedtls_ssl_context *ssl, int downsizing,
size_t out_buf_new_len)
{
int modified = 0;
size_t written_in = 0, iv_offset_in = 0, len_offset_in = 0;
size_t written_in = 0, iv_offset_in = 0, len_offset_in = 0, hdr_in = 0;
size_t written_out = 0, iv_offset_out = 0, len_offset_out = 0;
size_t hshdr_in = 0;
if (ssl->in_buf != NULL) {
written_in = ssl->in_msg - ssl->in_buf;
iv_offset_in = ssl->in_iv - ssl->in_buf;
len_offset_in = ssl->in_len - ssl->in_buf;
hdr_in = ssl->in_hdr - ssl->in_buf;
if (ssl->in_hshdr != NULL) {
hshdr_in = ssl->in_hshdr - ssl->in_buf;
}
if (downsizing ?
ssl->in_buf_len > in_buf_new_len && ssl->in_left < in_buf_new_len :
ssl->in_buf_len < in_buf_new_len) {
@ -380,7 +385,10 @@ static void handle_buffer_resizing(mbedtls_ssl_context *ssl, int downsizing,
}
if (modified) {
/* Update pointers here to avoid doing it twice. */
mbedtls_ssl_reset_in_out_pointers(ssl);
ssl->in_hdr = ssl->in_buf + hdr_in;
mbedtls_ssl_update_in_pointers(ssl);
mbedtls_ssl_reset_out_pointers(ssl);
/* Fields below might not be properly updated with record
* splitting or with CID, so they are manually updated here. */
ssl->out_msg = ssl->out_buf + written_out;
@ -390,6 +398,9 @@ static void handle_buffer_resizing(mbedtls_ssl_context *ssl, int downsizing,
ssl->in_msg = ssl->in_buf + written_in;
ssl->in_len = ssl->in_buf + len_offset_in;
ssl->in_iv = ssl->in_buf + iv_offset_in;
if (ssl->in_hshdr != NULL) {
ssl->in_hshdr = ssl->in_buf + hshdr_in;
}
}
}
#endif /* MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH */
@ -1483,6 +1494,8 @@ void mbedtls_ssl_session_reset_msg_layer(mbedtls_ssl_context *ssl,
ssl->in_hslen = 0;
ssl->keep_current_message = 0;
ssl->transform_in = NULL;
ssl->in_hshdr = NULL;
ssl->in_hsfraglen = 0;
#if defined(MBEDTLS_SSL_PROTO_DTLS)
ssl->next_record_offset = 0;