From patchwork Tue Feb 2 05:37:34 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhouyi Zhou X-Patchwork-Id: 576982 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id C29A3140557 for ; Tue, 2 Feb 2016 16:41:04 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752252AbcBBFkt (ORCPT ); Tue, 2 Feb 2016 00:40:49 -0500 Received: from smtp23.cstnet.cn ([159.226.251.23]:35373 "EHLO cstnet.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751120AbcBBFkr (ORCPT ); Tue, 2 Feb 2016 00:40:47 -0500 Received: from localhost.localdomain (unknown [159.226.43.96]) by app3 (Coremail) with SMTP id SQCowJDbX+XhQLBWhN9cBA--.4463S3; Tue, 02 Feb 2016 13:38:48 +0800 (CST) From: Zhouyi Zhou To: eric.dumazet@gmail.com, pablo@netfilter.org, kaber@trash.net, kadlec@blackhole.kfki.hu, davem@davemloft.net, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, fw@strlen.de, gnomes@lxorguk.ukuu.org.uk, sergei.shtylyov@cogentembedded.com Cc: Zhouyi Zhou , Zhouyi Zhou Subject: [PATCH V5] netfilter: h323: avoid potential attack Date: Tue, 2 Feb 2016 13:37:34 +0800 Message-Id: <1454391454-22359-1-git-send-email-zhouzhouyi@gmail.com> X-Mailer: git-send-email 1.9.1 X-CM-TRANSID: SQCowJDbX+XhQLBWhN9cBA--.4463S3 X-Coremail-Antispam: 1UD129KBjvJXoWxCF45tFy7uw4DJr4kKw48JFb_yoW5XF4rpF s3Ka45t3y2yr42vF4jyF48CF1Yvrn3KF1xW393A34Fy3WxAr4DWa1DKFy2qrWFqr93tr12 yr4Yqa1xGF4DJ3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUk214x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84ACjcxK6xIIjxv20xvE14 v26r1I6r4UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j6F4UM28EF7xvwVC2z280aVAF wI0_Cr1j6rxdM28EF7xvwVC2z280aVCY1x0267AKxVWxJr0_GcWle2I262IYc4CY6c8Ij2 8IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jrv_JF1l Yx0Ex4A2jsIE14v26r4j6F4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrw ACjcxG0xvY0x0EwIxGrVCF72vEw4AK0wACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIE c7CjxVA2Y2ka0xkIwI1lc2xSY4AK67AK6r4rMxAIw28IcxkI7VAKI48JMI8I3I0E5I8CrV AFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCI 42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42 IY6xAIw20EY4v20xvaj40_WFyUJVCq3wCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E 87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvj4RJUUUUUUUU X-CM-SenderInfo: p2kr365krx5x46jptx3oof0z/ Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org I think hackers chould build a malicious h323 packet to overflow the pointer p which will panic during the memcpy(addr, p, len) For example, he may fabricate a very large taddr->ipAddress.ip. In order to avoid this, I add a valid memory reference check in get_h2x5_addr functions. As suggested by Eric, this module is protected by a lock (nf_h323_lock) so adding a variable h323_buffer_valid_bytes that would contain the number of valid bytes would not require to change prototypes of get_h2x5_addr. Signed-off-by: Zhouyi Zhou --- net/netfilter/nf_conntrack_h323_main.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c index 9511af0..21665ec 100644 --- a/net/netfilter/nf_conntrack_h323_main.c +++ b/net/netfilter/nf_conntrack_h323_main.c @@ -110,6 +110,25 @@ int (*nat_q931_hook) (struct sk_buff *skb, static DEFINE_SPINLOCK(nf_h323_lock); static char *h323_buffer; +static int h323_buffer_valid_bytes; + +static bool h323_buffer_ref_valid(void *p, int len) +{ + + if ((unsigned long)len > h323_buffer_valid_bytes) { + return false; + } + + if (p + len > (void *)h323_buffer + h323_buffer_valid_bytes) { + return false; + } + + if (p < (void *)h323_buffer) { + return false; + } + + return true; +} static struct nf_conntrack_helper nf_conntrack_helper_h245; static struct nf_conntrack_helper nf_conntrack_helper_q931[]; @@ -145,6 +164,7 @@ static int get_tpkt_data(struct sk_buff *skb, unsigned int protoff, if (*data == NULL) { /* first TPKT */ /* Get first TPKT pointer */ + h323_buffer_valid_bytes = tcpdatalen; tpkt = skb_header_pointer(skb, tcpdataoff, tcpdatalen, h323_buffer); BUG_ON(tpkt == NULL); @@ -247,6 +267,9 @@ static int get_h245_addr(struct nf_conn *ct, const unsigned char *data, return 0; } + if (!h323_buffer_ref_valid((void *)p, len + sizeof(__be16))) + return 0; + memcpy(addr, p, len); memset((void *)addr + len, 0, sizeof(*addr) - len); memcpy(port, p + len, sizeof(__be16)); @@ -669,6 +692,9 @@ int get_h225_addr(struct nf_conn *ct, unsigned char *data, return 0; } + if (!h323_buffer_ref_valid((void *)p, len + sizeof(__be16))) + return 0; + memcpy(addr, p, len); memset((void *)addr + len, 0, sizeof(*addr) - len); memcpy(port, p + len, sizeof(__be16)); @@ -1248,6 +1274,7 @@ static unsigned char *get_udp_data(struct sk_buff *skb, unsigned int protoff, if (dataoff >= skb->len) return NULL; *datalen = skb->len - dataoff; + h323_buffer_valid_bytes = *datalen; return skb_header_pointer(skb, dataoff, *datalen, h323_buffer); }