From 99fb785a5f85315b95288921a321a935ea29a51e Mon Sep 17 00:00:00 2001 From: Matt Caswell Date: Fri, 31 May 2024 11:14:33 +0100 Subject: [PATCH 01/10] Fix SSL_select_next_proto Ensure that the provided client list is non-NULL and starts with a valid entry. When called from the ALPN callback the client list should already have been validated by OpenSSL so this should not cause a problem. When called from the NPN callback the client list is locally configured and will not have already been validated. Therefore SSL_select_next_proto should not assume that it is correctly formatted. We implement stricter checking of the client protocol list. We also do the same for the server list while we are about it. CVE-2024-5535 Reviewed-by: Neil Horman Reviewed-by: Tomas Mraz (Merged from https://github.com/openssl/openssl/pull/24717) --- ssl/ssl_lib.c | 63 ++++++++++++++++++++++++++++++++------------------- 1 file changed, 40 insertions(+), 23 deletions(-) diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c index 016135fe18..cf52b317cf 100644 --- a/ssl/ssl_lib.c +++ b/ssl/ssl_lib.c @@ -3518,37 +3518,54 @@ int SSL_select_next_proto(unsigned char **out, unsigned char *outlen, unsigned int server_len, const unsigned char *client, unsigned int client_len) { - unsigned int i, j; - const unsigned char *result; - int status = OPENSSL_NPN_UNSUPPORTED; + PACKET cpkt, csubpkt, spkt, ssubpkt; + + if (!PACKET_buf_init(&cpkt, client, client_len) + || !PACKET_get_length_prefixed_1(&cpkt, &csubpkt) + || PACKET_remaining(&csubpkt) == 0) { + *out = NULL; + *outlen = 0; + return OPENSSL_NPN_NO_OVERLAP; + } + + /* + * Set the default opportunistic protocol. Will be overwritten if we find + * a match. + */ + *out = (unsigned char *)PACKET_data(&csubpkt); + *outlen = (unsigned char)PACKET_remaining(&csubpkt); /* * For each protocol in server preference order, see if we support it. */ - for (i = 0; i < server_len;) { - for (j = 0; j < client_len;) { - if (server[i] == client[j] && - memcmp(&server[i + 1], &client[j + 1], server[i]) == 0) { - /* We found a match */ - result = &server[i]; - status = OPENSSL_NPN_NEGOTIATED; - goto found; + if (PACKET_buf_init(&spkt, server, server_len)) { + while (PACKET_get_length_prefixed_1(&spkt, &ssubpkt)) { + if (PACKET_remaining(&ssubpkt) == 0) + continue; /* Invalid - ignore it */ + if (PACKET_buf_init(&cpkt, client, client_len)) { + while (PACKET_get_length_prefixed_1(&cpkt, &csubpkt)) { + if (PACKET_equal(&csubpkt, PACKET_data(&ssubpkt), + PACKET_remaining(&ssubpkt))) { + /* We found a match */ + *out = (unsigned char *)PACKET_data(&ssubpkt); + *outlen = (unsigned char)PACKET_remaining(&ssubpkt); + return OPENSSL_NPN_NEGOTIATED; + } + } + /* Ignore spurious trailing bytes in the client list */ + } else { + /* This should never happen */ + return OPENSSL_NPN_NO_OVERLAP; } - j += client[j]; - j++; } - i += server[i]; - i++; + /* Ignore spurious trailing bytes in the server list */ } - /* There's no overlap between our protocols and the server's list. */ - result = client; - status = OPENSSL_NPN_NO_OVERLAP; - - found: - *out = (unsigned char *)result + 1; - *outlen = result[0]; - return status; + /* + * There's no overlap between our protocols and the server's list. We use + * the default opportunistic protocol selected earlier + */ + return OPENSSL_NPN_NO_OVERLAP; } #ifndef OPENSSL_NO_NEXTPROTONEG -- 2.46.0