Fix CVE-2024-5535

CHANGES

@@ -4,6 +4,8 @@
 
  Changes between 8.4.0 and 8.5.0 [xx XXX xxxx]
 
+  *) 修复CVE-2024-5535
+
   *) 修复CVE-2024-4741
 
   *) 修复CVE-2024-4603

ssl/ssl_lib.c

@@ -3010,37 +3010,54 @@ 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

ssl/statem/extensions_clnt.c

@@ -1650,7 +1650,8 @@ int tls_parse_stoc_npn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
                                   PACKET_data(pkt),
                                   PACKET_remaining(pkt),
                                   s->ctx->ext.npn_select_cb_arg) !=
-             SSL_TLSEXT_ERR_OK) {
+                                  SSL_TLSEXT_ERR_OK
+            || selected_len == 0) {
         SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, SSL_R_BAD_EXTENSION);
         return 0;
     }
@@ -1679,6 +1680,8 @@ int tls_parse_stoc_alpn(SSL *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) {
@@ -1697,6 +1700,28 @@ int tls_parse_stoc_alpn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
         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) {

ssl/statem/extensions_srvr.c

@@ -1566,9 +1566,10 @@ EXT_RETURN tls_construct_stoc_next_proto_neg(SSL *s, WPACKET *pkt,
             return EXT_RETURN_FAIL;
         }
         s->s3.npn_seen = 1;
+        return EXT_RETURN_SENT;
     }
 
-    return EXT_RETURN_SENT;
+    return EXT_RETURN_NOT_SENT;
 }
 #endif
 

ssl/statem_ntls/ntls_extensions_clnt.c

@@ -644,7 +644,8 @@ int tls_parse_stoc_npn_ntls(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
                                   PACKET_data(pkt),
                                   PACKET_remaining(pkt),
                                   s->ctx->ext.npn_select_cb_arg) !=
-             SSL_TLSEXT_ERR_OK) {
+                                  SSL_TLSEXT_ERR_OK
+            || selected_len == 0) {
         SSLfatal_ntls(s, SSL_AD_HANDSHAKE_FAILURE, SSL_R_BAD_EXTENSION);
         return 0;
     }
@@ -673,6 +674,8 @@ int tls_parse_stoc_alpn_ntls(SSL *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) {
@@ -691,6 +694,28 @@ int tls_parse_stoc_alpn_ntls(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
         SSLfatal_ntls(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_ntls(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_ntls(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) {

ssl/statem_ntls/ntls_extensions_srvr.c

@@ -587,9 +587,10 @@ EXT_RETURN tls_construct_stoc_next_proto_neg_ntls(SSL *s, WPACKET *pkt,
             return EXT_RETURN_FAIL;
         }
         s->s3.npn_seen = 1;
+        return EXT_RETURN_SENT;
     }
 
-    return EXT_RETURN_SENT;
+    return EXT_RETURN_NOT_SENT;
 }
 #endif
 

test/helpers/handshake.c

@@ -349,6 +349,12 @@ static int parse_protos(const char *protos, unsigned char **out, size_t *outlen)
 
     len = strlen(protos);
 
+    if (len == 0) {
+        *out = NULL;
+        *outlen = 0;
+        return 1;
+    }
+
     /* Should never have reuse. */
     if (!TEST_ptr_null(*out)
             /* Test values are small, so we omit length limit checks. */

test/recipes/70-test_npn.t

@@ -0,0 +1,73 @@
+#! /usr/bin/env perl
+# Copyright 2024 The OpenSSL Project Authors. All Rights Reserved.
+#
+# Licensed under the Apache License 2.0 (the "License").  You may not use
+# this file except in compliance with the License.  You can obtain a copy
+# in the file LICENSE in the source distribution or at
+# https://www.openssl.org/source/license.html
+
+use strict;
+use OpenSSL::Test qw/:DEFAULT cmdstr srctop_file/;
+use OpenSSL::Test::Utils;
+
+use TLSProxy::Proxy;
+
+my $test_name = "test_npn";
+setup($test_name);
+
+plan skip_all => "TLSProxy isn't usable on $^O"
+    if $^O =~ /^(VMS)$/;
+
+plan skip_all => "$test_name needs the dynamic engine feature enabled"
+    if disabled("engine") || disabled("dynamic-engine");
+
+plan skip_all => "$test_name needs the sock feature enabled"
+    if disabled("sock");
+
+plan skip_all => "$test_name needs NPN enabled"
+    if disabled("nextprotoneg");
+
+plan skip_all => "$test_name needs TLSv1.2 enabled"
+    if disabled("tls1_2");
+
+my $proxy = TLSProxy::Proxy->new(
+    undef,
+    cmdstr(app(["openssl"]), display => 1),
+    srctop_file("apps", "server.pem"),
+    (!$ENV{HARNESS_ACTIVE} || $ENV{HARNESS_VERBOSE})
+);
+
+$proxy->start() or plan skip_all => "Unable to start up Proxy for tests";
+plan tests => 1;
+
+my $npnseen = 0;
+
+# Test 1: Check sending an empty NextProto message from the client works. This is
+#         valid as per the spec, but OpenSSL does not allow you to send it.
+#         Therefore we must be prepared to receive such a message but we cannot
+#         generate it except via TLSProxy
+$proxy->clear();
+$proxy->filter(\&npn_filter);
+$proxy->clientflags("-nextprotoneg foo -no_tls1_3");
+$proxy->serverflags("-nextprotoneg foo");
+$proxy->start();
+ok($npnseen && TLSProxy::Message->success(), "Empty NPN message");
+
+sub npn_filter
+{
+    my $proxy = shift;
+    my $message;
+
+    # The NextProto message always appears in flight 2
+    return if $proxy->flight != 2;
+
+    foreach my $message (@{$proxy->message_list}) {
+        if ($message->mt == TLSProxy::Message::MT_NEXT_PROTO) {
+            # Our TLSproxy NextProto message support doesn't support parsing of
+            # the message. If we repack it just creates an empty NextProto
+            # message - which is exactly the scenario we want to test here.
+            $message->repack();
+            $npnseen = 1;
+        }
+    }
+}