From patchwork Tue Aug 15 22:29:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Westphal X-Patchwork-Id: 13354372 X-Patchwork-Delegate: kuba@kernel.org Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7187A1ADD3 for ; Tue, 15 Aug 2023 22:30:52 +0000 (UTC) Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 742AC1BFF; Tue, 15 Aug 2023 15:30:51 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1qW2Yp-0004cY-Hu; Wed, 16 Aug 2023 00:30:47 +0200 From: Florian Westphal To: Cc: Paolo Abeni , "David S. Miller" , Eric Dumazet , Jakub Kicinski , , Pablo Neira Ayuso Subject: [PATCH net 7/9] netfilter: nf_tables: fix GC transaction races with netns and netlink event exit path Date: Wed, 16 Aug 2023 00:29:57 +0200 Message-ID: <20230815223011.7019-8-fw@strlen.de> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230815223011.7019-1-fw@strlen.de> References: <20230815223011.7019-1-fw@strlen.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_BLOCKED,SPF_HELO_PASS, SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@kernel.org From: Pablo Neira Ayuso Netlink event path is missing a synchronization point with GC transactions. Add GC sequence number update to netns release path and netlink event path, any GC transaction losing race will be discarded. Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane") Signed-off-by: Pablo Neira Ayuso Signed-off-by: Florian Westphal --- net/netfilter/nf_tables_api.c | 36 +++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 6f31022cacc6..8ac4dd8be1a2 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -9739,6 +9739,22 @@ static void nft_set_commit_update(struct list_head *set_update_list) } } +static unsigned int nft_gc_seq_begin(struct nftables_pernet *nft_net) +{ + unsigned int gc_seq; + + /* Bump gc counter, it becomes odd, this is the busy mark. */ + gc_seq = READ_ONCE(nft_net->gc_seq); + WRITE_ONCE(nft_net->gc_seq, ++gc_seq); + + return gc_seq; +} + +static void nft_gc_seq_end(struct nftables_pernet *nft_net, unsigned int gc_seq) +{ + WRITE_ONCE(nft_net->gc_seq, ++gc_seq); +} + static int nf_tables_commit(struct net *net, struct sk_buff *skb) { struct nftables_pernet *nft_net = nft_pernet(net); @@ -9824,9 +9840,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb) WRITE_ONCE(nft_net->base_seq, base_seq); - /* Bump gc counter, it becomes odd, this is the busy mark. */ - gc_seq = READ_ONCE(nft_net->gc_seq); - WRITE_ONCE(nft_net->gc_seq, ++gc_seq); + gc_seq = nft_gc_seq_begin(nft_net); /* step 3. Start new generation, rules_gen_X now in use. */ net->nft.gencursor = nft_gencursor_next(net); @@ -10039,7 +10053,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb) nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN); nf_tables_commit_audit_log(&adl, nft_net->base_seq); - WRITE_ONCE(nft_net->gc_seq, ++gc_seq); + nft_gc_seq_end(nft_net, gc_seq); nf_tables_commit_release(net); return 0; @@ -11040,6 +11054,7 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event, struct net *net = n->net; unsigned int deleted; bool restart = false; + unsigned int gc_seq; if (event != NETLINK_URELEASE || n->protocol != NETLINK_NETFILTER) return NOTIFY_DONE; @@ -11047,6 +11062,9 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event, nft_net = nft_pernet(net); deleted = 0; mutex_lock(&nft_net->commit_mutex); + + gc_seq = nft_gc_seq_begin(nft_net); + if (!list_empty(&nf_tables_destroy_list)) rcu_barrier(); again: @@ -11069,6 +11087,8 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event, if (restart) goto again; } + nft_gc_seq_end(nft_net, gc_seq); + mutex_unlock(&nft_net->commit_mutex); return NOTIFY_DONE; @@ -11106,12 +11126,20 @@ static void __net_exit nf_tables_pre_exit_net(struct net *net) static void __net_exit nf_tables_exit_net(struct net *net) { struct nftables_pernet *nft_net = nft_pernet(net); + unsigned int gc_seq; mutex_lock(&nft_net->commit_mutex); + + gc_seq = nft_gc_seq_begin(nft_net); + if (!list_empty(&nft_net->commit_list) || !list_empty(&nft_net->module_list)) __nf_tables_abort(net, NFNL_ABORT_NONE); + __nft_release_tables(net); + + nft_gc_seq_end(nft_net, gc_seq); + mutex_unlock(&nft_net->commit_mutex); WARN_ON_ONCE(!list_empty(&nft_net->tables)); WARN_ON_ONCE(!list_empty(&nft_net->module_list));