From patchwork Tue Jun 21 08:56:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 12888869 X-Patchwork-Delegate: kuba@kernel.org 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 96E7FC43334 for ; Tue, 21 Jun 2022 08:56:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347800AbiFUI4p (ORCPT ); Tue, 21 Jun 2022 04:56:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41500 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346241AbiFUI4k (ORCPT ); Tue, 21 Jun 2022 04:56:40 -0400 Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DA8EA26ACB; Tue, 21 Jun 2022 01:56:29 -0700 (PDT) From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com Subject: [PATCH net 4/5] netfilter: nf_dup_netdev: do not push mac header a second time Date: Tue, 21 Jun 2022 10:56:17 +0200 Message-Id: <20220621085618.3975-5-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220621085618.3975-1-pablo@netfilter.org> References: <20220621085618.3975-1-pablo@netfilter.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Florian Westphal Eric reports skb_under_panic when using dup/fwd via bond+egress hook. Before pushing mac header, we should make sure that we're called from ingress to put back what was pulled earlier. In egress case, the MAC header is already there; we should leave skb alone. While at it be more careful here: skb might have been altered and headroom reduced, so add a skb_cow() before so that headroom is increased if necessary. nf_do_netdev_egress() assumes skb ownership (it normally ends with a call to dev_queue_xmit), so we must free the packet on error. Fixes: f87b9464d152 ("netfilter: nft_fwd_netdev: Support egress hook") Reported-by: Eric Garver Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_dup_netdev.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/net/netfilter/nf_dup_netdev.c b/net/netfilter/nf_dup_netdev.c index 7873bd1389c3..13b7f6a66086 100644 --- a/net/netfilter/nf_dup_netdev.c +++ b/net/netfilter/nf_dup_netdev.c @@ -13,10 +13,16 @@ #include #include -static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev) +static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev, + enum nf_dev_hooks hook) { - if (skb_mac_header_was_set(skb)) + if (hook == NF_NETDEV_INGRESS && skb_mac_header_was_set(skb)) { + if (skb_cow_head(skb, skb->mac_len)) { + kfree_skb(skb); + return; + } skb_push(skb, skb->mac_len); + } skb->dev = dev; skb_clear_tstamp(skb); @@ -33,7 +39,7 @@ void nf_fwd_netdev_egress(const struct nft_pktinfo *pkt, int oif) return; } - nf_do_netdev_egress(pkt->skb, dev); + nf_do_netdev_egress(pkt->skb, dev, nft_hook(pkt)); } EXPORT_SYMBOL_GPL(nf_fwd_netdev_egress); @@ -48,7 +54,7 @@ void nf_dup_netdev_egress(const struct nft_pktinfo *pkt, int oif) skb = skb_clone(pkt->skb, GFP_ATOMIC); if (skb) - nf_do_netdev_egress(skb, dev); + nf_do_netdev_egress(skb, dev, nft_hook(pkt)); } EXPORT_SYMBOL_GPL(nf_dup_netdev_egress);