From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 5/8] netfilter: nft_compat: do not dump private area Date: Mon, 22 Oct 2018 22:07:21 +0200 Message-ID: <20181022200724.25806-6-pablo@netfilter.org> References: <20181022200724.25806-1-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]:45114 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728061AbeJWE1i (ORCPT ); Tue, 23 Oct 2018 00:27:38 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 54A1A1E8F9B for ; Mon, 22 Oct 2018 22:07:38 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 1AEBCDA846 for ; Mon, 22 Oct 2018 22:07:38 +0200 (CEST) In-Reply-To: <20181022200724.25806-1-pablo@netfilter.org> Sender: netdev-owner@vger.kernel.org List-ID: Zero pad private area, otherwise we expose private kernel pointer to userspace. This patch also zeroes the tail area after the ->matchsize and ->targetsize that results from XT_ALIGN(). Fixes: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables") Reported-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_compat.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c index 32535eea51b2..768292eac2a4 100644 --- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -290,6 +290,24 @@ nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr) module_put(target->me); } +static int nft_extension_dump_info(struct sk_buff *skb, int attr, + const void *info, + unsigned int size, unsigned int user_size) +{ + unsigned int info_size, aligned_size = XT_ALIGN(size); + struct nlattr *nla; + + nla = nla_reserve(skb, attr, aligned_size); + if (!nla) + return -1; + + info_size = user_size ? : size; + memcpy(nla_data(nla), info, info_size); + memset(nla_data(nla) + info_size, 0, aligned_size - info_size); + + return 0; +} + static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr) { const struct xt_target *target = expr->ops->data; @@ -297,7 +315,8 @@ static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr) if (nla_put_string(skb, NFTA_TARGET_NAME, target->name) || nla_put_be32(skb, NFTA_TARGET_REV, htonl(target->revision)) || - nla_put(skb, NFTA_TARGET_INFO, XT_ALIGN(target->targetsize), info)) + nft_extension_dump_info(skb, NFTA_TARGET_INFO, info, + target->targetsize, target->usersize)) goto nla_put_failure; return 0; @@ -532,7 +551,8 @@ static int __nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr, if (nla_put_string(skb, NFTA_MATCH_NAME, match->name) || nla_put_be32(skb, NFTA_MATCH_REV, htonl(match->revision)) || - nla_put(skb, NFTA_MATCH_INFO, XT_ALIGN(match->matchsize), info)) + nft_extension_dump_info(skb, NFTA_MATCH_INFO, info, + match->matchsize, match->usersize)) goto nla_put_failure; return 0; -- 2.11.0