From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 11/12] ebtables: arpreply: Add the standard target sanity check Date: Fri, 19 May 2017 10:33:52 +0200 Message-ID: <1495182833-2272-12-git-send-email-pablo@netfilter.org> References: <1495182833-2272-1-git-send-email-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: Received: from mail.us.es ([193.147.175.20]:44022 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754617AbdESIeZ (ORCPT ); Fri, 19 May 2017 04:34:25 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 4BE301DA091 for ; Fri, 19 May 2017 10:34:18 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 3CB8FFF2F8 for ; Fri, 19 May 2017 10:34:18 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 5A326100A7C for ; Fri, 19 May 2017 10:34:15 +0200 (CEST) In-Reply-To: <1495182833-2272-1-git-send-email-pablo@netfilter.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Gao Feng The info->target comes from userspace and it would be used directly. So we need to add the sanity check to make sure it is a valid standard target, although the ebtables tool has already checked it. Kernel needs to validate anything coming from userspace. If the target is set as an evil value, it would break the ebtables and cause a panic. Because the non-standard target is treated as one offset. Now add one helper function ebt_invalid_target, and we would replace the macro INVALID_TARGET later. Signed-off-by: Gao Feng Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter_bridge/ebtables.h | 5 +++++ net/bridge/netfilter/ebt_arpreply.c | 3 +++ 2 files changed, 8 insertions(+) diff --git a/include/linux/netfilter_bridge/ebtables.h b/include/linux/netfilter_bridge/ebtables.h index a30efb437e6d..e0cbf17af780 100644 --- a/include/linux/netfilter_bridge/ebtables.h +++ b/include/linux/netfilter_bridge/ebtables.h @@ -125,4 +125,9 @@ extern unsigned int ebt_do_table(struct sk_buff *skb, /* True if the target is not a standard target */ #define INVALID_TARGET (info->target < -NUM_STANDARD_TARGETS || info->target >= 0) +static inline bool ebt_invalid_target(int target) +{ + return (target < -NUM_STANDARD_TARGETS || target >= 0); +} + #endif diff --git a/net/bridge/netfilter/ebt_arpreply.c b/net/bridge/netfilter/ebt_arpreply.c index 5929309beaa1..db85230e49c3 100644 --- a/net/bridge/netfilter/ebt_arpreply.c +++ b/net/bridge/netfilter/ebt_arpreply.c @@ -68,6 +68,9 @@ static int ebt_arpreply_tg_check(const struct xt_tgchk_param *par) if (e->ethproto != htons(ETH_P_ARP) || e->invflags & EBT_IPROTO) return -EINVAL; + if (ebt_invalid_target(info->target)) + return -EINVAL; + return 0; } -- 2.1.4