From patchwork Fri Feb 5 00:17:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 376715 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1914CC433E0 for ; Fri, 5 Feb 2021 00:18:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC78364F3C for ; Fri, 5 Feb 2021 00:18:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231740AbhBEASU (ORCPT ); Thu, 4 Feb 2021 19:18:20 -0500 Received: from correo.us.es ([193.147.175.20]:40600 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231773AbhBEASQ (ORCPT ); Thu, 4 Feb 2021 19:18:16 -0500 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 955692A3272 for ; Fri, 5 Feb 2021 01:17:34 +0100 (CET) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 84FFBDA78C for ; Fri, 5 Feb 2021 01:17:34 +0100 (CET) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 7A436DA78A; Fri, 5 Feb 2021 01:17:34 +0100 (CET) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 39AE9DA722; Fri, 5 Feb 2021 01:17:32 +0100 (CET) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Fri, 05 Feb 2021 01:17:32 +0100 (CET) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from localhost.localdomain (unknown [90.77.255.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: pneira@us.es) by entrada.int (Postfix) with ESMTPSA id 0BB3842EF9E1; Fri, 5 Feb 2021 01:17:32 +0100 (CET) X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org Subject: [PATCH net 3/4] netfilter: nftables: fix possible UAF over chains from packet path in netns Date: Fri, 5 Feb 2021 01:17:26 +0100 Message-Id: <20210205001727.2125-4-pablo@netfilter.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210205001727.2125-1-pablo@netfilter.org> References: <20210205001727.2125-1-pablo@netfilter.org> MIME-Version: 1.0 X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Although hooks are released via call_rcu(), chain and rule objects are immediately released while packets are still walking over these bits. This patch adds the .pre_exit callback which is invoked before synchronize_rcu() in the netns framework to stay safe. Remove a comment which is not valid anymore since the core does not use synchronize_net() anymore since 8c873e219970 ("netfilter: core: free hooks with call_rcu"). Suggested-by: Florian Westphal Fixes: df05ef874b28 ("netfilter: nf_tables: release objects on netns destruction") Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 8d3aa97b52e7..43fe80f10313 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -8949,6 +8949,17 @@ int __nft_release_basechain(struct nft_ctx *ctx) } EXPORT_SYMBOL_GPL(__nft_release_basechain); +static void __nft_release_hooks(struct net *net) +{ + struct nft_table *table; + struct nft_chain *chain; + + list_for_each_entry(table, &net->nft.tables, list) { + list_for_each_entry(chain, &table->chains, list) + nf_tables_unregister_hook(net, table, chain); + } +} + static void __nft_release_tables(struct net *net) { struct nft_flowtable *flowtable, *nf; @@ -8964,10 +8975,6 @@ static void __nft_release_tables(struct net *net) list_for_each_entry_safe(table, nt, &net->nft.tables, list) { ctx.family = table->family; - - list_for_each_entry(chain, &table->chains, list) - nf_tables_unregister_hook(net, table, chain); - /* No packets are walking on these chains anymore. */ ctx.table = table; list_for_each_entry(chain, &table->chains, list) { ctx.chain = chain; @@ -9016,6 +9023,11 @@ static int __net_init nf_tables_init_net(struct net *net) return 0; } +static void __net_exit nf_tables_pre_exit_net(struct net *net) +{ + __nft_release_hooks(net); +} + static void __net_exit nf_tables_exit_net(struct net *net) { mutex_lock(&net->nft.commit_mutex); @@ -9029,8 +9041,9 @@ static void __net_exit nf_tables_exit_net(struct net *net) } static struct pernet_operations nf_tables_net_ops = { - .init = nf_tables_init_net, - .exit = nf_tables_exit_net, + .init = nf_tables_init_net, + .pre_exit = nf_tables_pre_exit_net, + .exit = nf_tables_exit_net, }; static int __init nf_tables_module_init(void)