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openssl/SOURCES/0131-Add-ALPN-validation-in...

63 lines
2.1 KiB

From 195e15421df113d7283aab2ccff8b8fb06df5465 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 21 Jun 2024 11:51:54 +0100
Subject: [PATCH 08/10] Add ALPN validation in the client
The ALPN protocol selected by the server must be one that we originally
advertised. We should verify that it is.
Follow on from CVE-2024-5535
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24717)
---
ssl/statem/extensions_clnt.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/ssl/statem/extensions_clnt.c b/ssl/statem/extensions_clnt.c
index 1ab3c13d57..ff9c009ee5 100644
--- a/ssl/statem/extensions_clnt.c
+++ b/ssl/statem/extensions_clnt.c
@@ -1590,6 +1590,8 @@ int tls_parse_stoc_alpn(SSL_CONNECTION *s, PACKET *pkt, unsigned int context,
X509 *x, size_t chainidx)
{
size_t len;
+ PACKET confpkt, protpkt;
+ int valid = 0;
/* We must have requested it. */
if (!s->s3.alpn_sent) {
@@ -1608,6 +1610,28 @@ int tls_parse_stoc_alpn(SSL_CONNECTION *s, PACKET *pkt, unsigned int context,
SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_R_BAD_EXTENSION);
return 0;
}
+
+ /* It must be a protocol that we sent */
+ if (!PACKET_buf_init(&confpkt, s->ext.alpn, s->ext.alpn_len)) {
+ SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
+ return 0;
+ }
+ while (PACKET_get_length_prefixed_1(&confpkt, &protpkt)) {
+ if (PACKET_remaining(&protpkt) != len)
+ continue;
+ if (memcmp(PACKET_data(pkt), PACKET_data(&protpkt), len) == 0) {
+ /* Valid protocol found */
+ valid = 1;
+ break;
+ }
+ }
+
+ if (!valid) {
+ /* The protocol sent from the server does not match one we advertised */
+ SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_R_BAD_EXTENSION);
+ return 0;
+ }
+
OPENSSL_free(s->s3.alpn_selected);
s->s3.alpn_selected = OPENSSL_malloc(len);
if (s->s3.alpn_selected == NULL) {
--
2.46.0