109 lines
4.1 KiB
Diff
109 lines
4.1 KiB
Diff
From e86ac436f0bd54d4517745483e2315650fae7b2c Mon Sep 17 00:00:00 2001
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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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Subject: [PATCH] Fix SSL_select_next_proto
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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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Reviewed-by: Tomas Mraz <tomas@openssl.org>
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Reviewed-by: Neil Horman <nhorman@openssl.org>
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(Merged from https://github.com/openssl/openssl/pull/24716)
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(cherry picked from commit 2ebbe2d7ca8551c4cb5fbb391ab9af411708090e)
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---
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ssl/ssl_lib.c | 63 ++++++++++++++++++++++++++++++++-------------------
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1 file changed, 40 insertions(+), 23 deletions(-)
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diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
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index 5ec6ac4b63dc5..4c20ac4bf1fe7 100644
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--- a/ssl/ssl_lib.c
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+++ b/ssl/ssl_lib.c
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@@ -3530,37 +3530,54 @@ 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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+
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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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+ * 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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