MSVSphere Packaging Team
3 months ago
parent
008b0e4a76
commit
cf321024d1
GPG Key ID:
B2B0B9F29E528FE8
@ -0,0 +1,255 @@
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From d1d4b56fe0c9a4200276d630f62108e1165e0990 Mon Sep 17 00:00:00 2001
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From: Maurizio Barbaro <mbarbaro@redhat.com>
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Date: Mon, 16 Sep 2024 10:53:53 +0200
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Subject: [PATCH] Backport openssl: SSL_select_next_proto buffer overread from 3.2
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Ensure that the provided client list is non-NULL and starts with a valid
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entry. When called from the ALPN callback the client list should already
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have been validated by OpenSSL so this should not cause a problem. When
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called from the NPN callback the client list is locally configured and
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will not have already been validated. Therefore SSL_select_next_proto
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should not assume that it is correctly formatted.
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We implement stricter checking of the client protocol list. We also do the
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same for the server list while we are about it.
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CVE-2024-5535
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From: Matt Caswell <matt@openssl.org>
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Date: Fri, 31 May 2024 11:14:33 +0100
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Merged from: https://github.com/openssl/openssl/pull/24717.
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Backported-by: Maurizio Barbaro <mbarbaro@redhat.com>
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we did't ported test changes because rely on internal testing framework.
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---
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doc/man3/SSL_CTX_set_alpn_select_cb.pod | 28 +++++++----
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ssl/ssl_lib.c | 64 +++++++++++++++----------
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ssl/statem/extensions_clnt.c | 30 +++++++++++-
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ssl/statem/extensions_srvr.c | 3 +-
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4 files changed, 89 insertions(+), 36 deletions(-)
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diff --git a/doc/man3/SSL_CTX_set_alpn_select_cb.pod b/doc/man3/SSL_CTX_set_alpn_select_cb.pod
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index e90caec..a3f8dfd 100644
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--- a/doc/man3/SSL_CTX_set_alpn_select_cb.pod
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+++ b/doc/man3/SSL_CTX_set_alpn_select_cb.pod
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@@ -43,7 +43,7 @@ SSL_select_next_proto, SSL_get0_alpn_selected, SSL_get0_next_proto_negotiated
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const unsigned char *server,
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unsigned int server_len,
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const unsigned char *client,
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- unsigned int client_len)
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+ unsigned int client_len);
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void SSL_get0_next_proto_negotiated(const SSL *s, const unsigned char **data,
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unsigned *len);
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@@ -52,7 +52,8 @@ SSL_select_next_proto, SSL_get0_alpn_selected, SSL_get0_next_proto_negotiated
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SSL_CTX_set_alpn_protos() and SSL_set_alpn_protos() are used by the client to
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set the list of protocols available to be negotiated. The B<protos> must be in
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protocol-list format, described below. The length of B<protos> is specified in
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-B<protos_len>.
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+B<protos_len>. Setting B<protos_len> to 0 clears any existing list of ALPN
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+protocols and no ALPN extension will be sent to the server.
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SSL_CTX_set_alpn_select_cb() sets the application callback B<cb> used by a
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server to select which protocol to use for the incoming connection. When B<cb>
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@@ -73,9 +74,16 @@ B<server_len> and B<client>, B<client_len> must be in the protocol-list format
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described below. The first item in the B<server>, B<server_len> list that
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matches an item in the B<client>, B<client_len> list is selected, and returned
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in B<out>, B<outlen>. The B<out> value will point into either B<server> or
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-B<client>, so it should be copied immediately. If no match is found, the first
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-item in B<client>, B<client_len> is returned in B<out>, B<outlen>. This
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-function can also be used in the NPN callback.
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+B<client>, so it should be copied immediately. The client list must include at
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+least one valid (nonempty) protocol entry in the list.
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+
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+The SSL_select_next_proto() helper function can be useful from either the ALPN
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+callback or the NPN callback (described below). If no match is found, the first
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+item in B<client>, B<client_len> is returned in B<out>, B<outlen> and
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+B<OPENSSL_NPN_NO_OVERLAP> is returned. This can be useful when implementating
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+the NPN callback. In the ALPN case, the value returned in B<out> and B<outlen>
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+must be ignored if B<OPENSSL_NPN_NO_OVERLAP> has been returned from
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+SSL_select_next_proto().
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SSL_CTX_set_next_proto_select_cb() sets a callback B<cb> that is called when a
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client needs to select a protocol from the server's provided list, and a
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@@ -85,9 +93,10 @@ must be set to point to the selected protocol (which may be within B<in>).
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The length of the protocol name must be written into B<outlen>. The
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server's advertised protocols are provided in B<in> and B<inlen>. The
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callback can assume that B<in> is syntactically valid. The client must
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-select a protocol. It is fatal to the connection if this callback returns
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-a value other than B<SSL_TLSEXT_ERR_OK>. The B<arg> parameter is the pointer
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-set via SSL_CTX_set_next_proto_select_cb().
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+select a protocol (although it may be an empty, zero length protocol). It is
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+fatal to the connection if this callback returns a value other than
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+B<SSL_TLSEXT_ERR_OK> or if the zero length protocol is selected. The B<arg>
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+parameter is the pointer set via SSL_CTX_set_next_proto_select_cb().
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SSL_CTX_set_next_protos_advertised_cb() sets a callback B<cb> that is called
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when a TLS server needs a list of supported protocols for Next Protocol
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@@ -149,7 +158,8 @@ A match was found and is returned in B<out>, B<outlen>.
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=item OPENSSL_NPN_NO_OVERLAP
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No match was found. The first item in B<client>, B<client_len> is returned in
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-B<out>, B<outlen>.
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+B<out>, B<outlen> (or B<NULL> and 0 in the case where the first entry in
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+B<client> is invalid).
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=back
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diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
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index c71c686..21e6c45 100644
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--- a/ssl/ssl_lib.c
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+++ b/ssl/ssl_lib.c
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@@ -2739,38 +2739,54 @@ int SSL_select_next_proto(unsigned char **out, unsigned char *outlen,
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unsigned int server_len,
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const unsigned char *client, unsigned int client_len)
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{
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- unsigned int i, j;
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- const unsigned char *result;
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- int status = OPENSSL_NPN_UNSUPPORTED;
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+ PACKET cpkt, csubpkt, spkt, ssubpkt;
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+ if (!PACKET_buf_init(&cpkt, client, client_len)
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+ || !PACKET_get_length_prefixed_1(&cpkt, &csubpkt)
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+ || PACKET_remaining(&csubpkt) == 0) {
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+ *out = NULL;
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+ *outlen = 0;
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+ return OPENSSL_NPN_NO_OVERLAP;
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+ }
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+
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+ /*
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+ * Set the default opportunistic protocol. Will be overwritten if we find
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+ * a match.
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+ */
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+ *out = (unsigned char *)PACKET_data(&csubpkt);
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+ *outlen = (unsigned char)PACKET_remaining(&csubpkt);
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/*
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* For each protocol in server preference order, see if we support it.
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*/
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- for (i = 0; i < server_len;) {
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- for (j = 0; j < client_len;) {
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- if (server[i] == client[j] &&
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- memcmp(&server[i + 1], &client[j + 1], server[i]) == 0) {
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- /* We found a match */
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- result = &server[i];
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- status = OPENSSL_NPN_NEGOTIATED;
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- goto found;
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+ if (PACKET_buf_init(&spkt, server, server_len)) {
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+ while (PACKET_get_length_prefixed_1(&spkt, &ssubpkt)) {
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+ if (PACKET_remaining(&ssubpkt) == 0)
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+ continue; /* Invalid - ignore it */
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+ if (PACKET_buf_init(&cpkt, client, client_len)) {
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+ while (PACKET_get_length_prefixed_1(&cpkt, &csubpkt)) {
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+ if (PACKET_equal(&csubpkt, PACKET_data(&ssubpkt),
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+ PACKET_remaining(&ssubpkt))) {
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+ /* We found a match */
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+ *out = (unsigned char *)PACKET_data(&ssubpkt);
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+ *outlen = (unsigned char)PACKET_remaining(&ssubpkt);
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+ return OPENSSL_NPN_NEGOTIATED;
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+ }
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+ }
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+ /* Ignore spurious trailing bytes in the client list */
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+ } else {
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+ /* This should never happen */
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+ return OPENSSL_NPN_NO_OVERLAP;
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}
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- j += client[j];
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- j++;
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}
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- i += server[i];
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- i++;
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+ /* Ignore spurious trailing bytes in the server list */
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}
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- /* There's no overlap between our protocols and the server's list. */
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- result = client;
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- status = OPENSSL_NPN_NO_OVERLAP;
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-
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- found:
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- *out = (unsigned char *)result + 1;
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- *outlen = result[0];
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- return status;
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-}
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+ /*
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+ * There's no overlap between our protocols and the server's list. We use
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+ * the default opportunistic protocol selected earlier
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+ */
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+ return OPENSSL_NPN_NO_OVERLAP;
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+ }
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#ifndef OPENSSL_NO_NEXTPROTONEG
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/*
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diff --git a/ssl/statem/extensions_clnt.c b/ssl/statem/extensions_clnt.c
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index ce8a757..cfde733 100644
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--- a/ssl/statem/extensions_clnt.c
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+++ b/ssl/statem/extensions_clnt.c
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@@ -1585,8 +1585,8 @@ int tls_parse_stoc_npn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
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if (s->ctx->ext.npn_select_cb(s, &selected, &selected_len,
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PACKET_data(pkt),
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PACKET_remaining(pkt),
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- s->ctx->ext.npn_select_cb_arg) !=
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- SSL_TLSEXT_ERR_OK) {
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+ s->ctx->ext.npn_select_cb_arg) != SSL_TLSEXT_ERR_OK
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+ || selected_len == 0) {
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SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, SSL_F_TLS_PARSE_STOC_NPN,
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SSL_R_BAD_EXTENSION);
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return 0;
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@@ -1617,6 +1617,8 @@ int tls_parse_stoc_alpn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
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size_t chainidx)
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{
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size_t len;
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+ PACKET confpkt, protpkt;
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+ int valid = 0;
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/* We must have requested it. */
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if (!s->s3->alpn_sent) {
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@@ -1637,6 +1639,30 @@ int tls_parse_stoc_alpn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
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SSL_R_BAD_EXTENSION);
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return 0;
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}
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+
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+ /* It must be a protocol that we sent */
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+ if (!PACKET_buf_init(&confpkt, s->ext.alpn, s->ext.alpn_len)) {
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+ SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_ALPN,
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+ ERR_R_INTERNAL_ERROR);
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+ return 0;
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+ }
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+ while (PACKET_get_length_prefixed_1(&confpkt, &protpkt)) {
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+ if (PACKET_remaining(&protpkt) != len)
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+ continue;
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+ if (memcmp(PACKET_data(pkt), PACKET_data(&protpkt), len) == 0) {
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+ /* Valid protocol found */
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+ valid = 1;
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+ break;
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+ }
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+ }
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+
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+ if (!valid) {
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+ /* The protocol sent from the server does not match one we advertised */
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+ SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_ALPN,
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+ SSL_R_BAD_EXTENSION);
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+ return 0;
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+ }
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+
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OPENSSL_free(s->s3->alpn_selected);
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s->s3->alpn_selected = OPENSSL_malloc(len);
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if (s->s3->alpn_selected == NULL) {
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diff --git a/ssl/statem/extensions_srvr.c b/ssl/statem/extensions_srvr.c
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index 3c7395c..4e3cbf8 100644
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--- a/ssl/statem/extensions_srvr.c
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+++ b/ssl/statem/extensions_srvr.c
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@@ -1559,9 +1559,10 @@ EXT_RETURN tls_construct_stoc_next_proto_neg(SSL *s, WPACKET *pkt,
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return EXT_RETURN_FAIL;
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}
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s->s3->npn_seen = 1;
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+ return EXT_RETURN_SENT;
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}
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- return EXT_RETURN_SENT;
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+ return EXT_RETURN_NOT_SENT;
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}
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#endif
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--
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2.46.0
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