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Correct legacy fallback for TLSv1.3 client.

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When falling back to the legacy TLS client, in the case where a server has
sent a TLS record that contains more than one handshake message, we also
need to stash the unprocessed record data for later processing. Otherwise
we end up with missing handshake data.

ok beck@ tb@
This commit is contained in:
jsing
2020-01-21 12:08:04 +00:00
parent d7a3f515e1
commit 05ea345ac2
3 changed files with 30 additions and 9 deletions
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28
lib/libssl/tls13_client.c
View File

@@ -1,4 +1,4 @@
/* $OpenBSD: tls13_client.c,v 1.21 2020/01/21 03:40:05 beck Exp $ */
/* $OpenBSD: tls13_client.c,v 1.22 2020/01/21 12:08:04 jsing Exp $ */
/*
* Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
*
@@ -115,14 +115,28 @@ tls13_use_legacy_client(struct tls13_ctx *ctx)
if (s->bbio != s->wbio)
s->wbio = BIO_push(s->bbio, s->wbio);
if (!tls13_handshake_msg_content(ctx->hs_msg, &cbs))
goto err;
/* Stash any unprocessed data from the last record. */
tls13_record_layer_rbuf(ctx->rl, &cbs);
if (CBS_len(&cbs) > 0) {
if (!CBS_write_bytes(&cbs,
S3I(s)->rbuf.buf + SSL3_RT_HEADER_LENGTH,
S3I(s)->rbuf.len - SSL3_RT_HEADER_LENGTH, NULL))
goto err;
if (!BUF_MEM_grow_clean(s->internal->init_buf, CBS_len(&cbs) + 4))
goto err;
S3I(s)->rbuf.offset = SSL3_RT_HEADER_LENGTH;
S3I(s)->rbuf.left = CBS_len(&cbs);
S3I(s)->rrec.type = SSL3_RT_HANDSHAKE;
S3I(s)->rrec.length = CBS_len(&cbs);
s->internal->rstate = SSL_ST_READ_BODY;
s->internal->packet = S3I(s)->rbuf.buf;
s->internal->packet_length = SSL3_RT_HEADER_LENGTH;
s->internal->mac_packet = 1;
}
if (!CBS_write_bytes(&cbs, s->internal->init_buf->data + 4,
s->internal->init_buf->length - 4, NULL))
/* Stash the current handshake message. */
tls13_handshake_msg_data(ctx->hs_msg, &cbs);
if (!CBS_write_bytes(&cbs, s->internal->init_buf->data,
s->internal->init_buf->length, NULL))
goto err;
S3I(s)->tmp.reuse_message = 1;

3
lib/libssl/tls13_internal.h
View File

@@ -1,4 +1,4 @@
/* $OpenBSD: tls13_internal.h,v 1.38 2020/01/21 03:40:05 beck Exp $ */
/* $OpenBSD: tls13_internal.h,v 1.39 2020/01/21 12:08:04 jsing Exp $ */
/*
* Copyright (c) 2018 Bob Beck <beck@openbsd.org>
* Copyright (c) 2018 Theo Buehler <tb@openbsd.org>
@@ -116,6 +116,7 @@ struct tls13_record_layer *tls13_record_layer_new(tls13_read_cb wire_read,
tls13_phh_recv_cb phh_recv_cb,
tls13_phh_sent_cb phh_sent_cb, void *cb_arg);
void tls13_record_layer_free(struct tls13_record_layer *rl);
void tls13_record_layer_rbuf(struct tls13_record_layer *rl, CBS *cbs);
void tls13_record_layer_set_aead(struct tls13_record_layer *rl,
const EVP_AEAD *aead);
void tls13_record_layer_set_hash(struct tls13_record_layer *rl,

8
lib/libssl/tls13_record_layer.c
View File

@@ -1,4 +1,4 @@
/* $OpenBSD: tls13_record_layer.c,v 1.17 2020/01/20 22:04:17 beck Exp $ */
/* $OpenBSD: tls13_record_layer.c,v 1.18 2020/01/21 12:08:04 jsing Exp $ */
/*
* Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
*
@@ -154,6 +154,12 @@ tls13_record_layer_free(struct tls13_record_layer *rl)
freezero(rl, sizeof(struct tls13_record_layer));
}
void
tls13_record_layer_rbuf(struct tls13_record_layer *rl, CBS *cbs)
{
CBS_dup(&rl->rbuf_cbs, cbs);
}
static int
tls13_record_layer_inc_seq_num(uint8_t *seq_num)
{