From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CBEDEC433EF for ; Tue, 1 Mar 2022 21:53:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238292AbiCAVya (ORCPT ); Tue, 1 Mar 2022 16:54:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238609AbiCAVy2 (ORCPT ); Tue, 1 Mar 2022 16:54:28 -0500 Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D8D898B6CF; Tue, 1 Mar 2022 13:53:46 -0800 (PST) Received: from localhost.localdomain (unknown [78.30.32.163]) by mail.netfilter.org (Postfix) with ESMTPSA id B8B80625FB; Tue, 1 Mar 2022 22:52:18 +0100 (CET) From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org Subject: [PATCH net 7/8] netfilter: nf_queue: handle socket prefetch Date: Tue, 1 Mar 2022 22:53:36 +0100 Message-Id: <20220301215337.378405-8-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220301215337.378405-1-pablo@netfilter.org> References: <20220301215337.378405-1-pablo@netfilter.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org From: Florian Westphal In case someone combines bpf socket assign and nf_queue, then we will queue an skb who references a struct sock that did not have its reference count incremented. As we leave rcu protection, there is no guarantee that skb->sk is still valid. For refcount-less skb->sk case, try to increment the reference count and then override the destructor. In case of failure we have two choices: orphan the skb and 'delete' preselect or let nf_queue() drop the packet. Do the latter, it should not happen during normal operation. Fixes: cf7fbe660f2d ("bpf: Add socket assign support") Acked-by: Joe Stringer Signed-off-by: Florian Westphal --- net/netfilter/nf_queue.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c index e39549c55945..63d1516816b1 100644 --- a/net/netfilter/nf_queue.c +++ b/net/netfilter/nf_queue.c @@ -180,6 +180,18 @@ static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state, break; } + if (skb_sk_is_prefetched(skb)) { + struct sock *sk = skb->sk; + + if (!sk_is_refcounted(sk)) { + if (!refcount_inc_not_zero(&sk->sk_refcnt)) + return -ENOTCONN; + + /* drop refcount on skb_orphan */ + skb->destructor = sock_edemux; + } + } + entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC); if (!entry) return -ENOMEM; -- 2.30.2