From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 AF8CA30FA7 for ; Wed, 20 Sep 2023 12:28:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3572FC433C7; Wed, 20 Sep 2023 12:28:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1695212934; bh=23TL1SrLYD9Me7SbWdXWOysmLjAEyNKynrCwOVGJPOI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Sv/zjVzTBTv1hbXUhsWo07Jzk92xTFf101Efxe+Sy5K1/iXiHlOaEtPYszVrN8OfA Vfei9HQvuAtZKTkMDgUKckZlZr5ocvP+/2hxsaIhyGgQSmVqBUqka1Z5CXKc9dH7x6 f1n/2mkHNjjwd+vs+pJaDfVFGIj3jQq1Qsg3OB80= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jordan Griege , Martin KaFai Lau , Stanislav Fomichev , Yan Zhai , Daniel Borkmann , Sasha Levin Subject: [PATCH 5.4 073/367] lwt: Fix return values of BPF xmit ops Date: Wed, 20 Sep 2023 13:27:30 +0200 Message-ID: <20230920112900.415317657@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230920112858.471730572@linuxfoundation.org> References: <20230920112858.471730572@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yan Zhai [ Upstream commit 29b22badb7a84b783e3a4fffca16f7768fb31205 ] BPF encap ops can return different types of positive values, such like NET_RX_DROP, NET_XMIT_CN, NETDEV_TX_BUSY, and so on, from function skb_do_redirect and bpf_lwt_xmit_reroute. At the xmit hook, such return values would be treated implicitly as LWTUNNEL_XMIT_CONTINUE in ip(6)_finish_output2. When this happens, skbs that have been freed would continue to the neighbor subsystem, causing use-after-free bug and kernel crashes. To fix the incorrect behavior, skb_do_redirect return values can be simply discarded, the same as tc-egress behavior. On the other hand, bpf_lwt_xmit_reroute returns useful errors to local senders, e.g. PMTU information. Thus convert its return values to avoid the conflict with LWTUNNEL_XMIT_CONTINUE. Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure") Reported-by: Jordan Griege Suggested-by: Martin KaFai Lau Suggested-by: Stanislav Fomichev Signed-off-by: Yan Zhai Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/0d2b878186cfe215fec6b45769c1cd0591d3628d.1692326837.git.yan@cloudflare.com Signed-off-by: Sasha Levin --- net/core/lwt_bpf.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index bf270b6a99b4f..017ed82611a8d 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -59,9 +59,8 @@ static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt, ret = BPF_OK; } else { skb_reset_mac_header(skb); - ret = skb_do_redirect(skb); - if (ret == 0) - ret = BPF_REDIRECT; + skb_do_redirect(skb); + ret = BPF_REDIRECT; } break; @@ -254,7 +253,7 @@ static int bpf_lwt_xmit_reroute(struct sk_buff *skb) err = dst_output(dev_net(skb_dst(skb)->dev), skb->sk, skb); if (unlikely(err)) - return err; + return net_xmit_errno(err); /* ip[6]_finish_output2 understand LWTUNNEL_XMIT_DONE */ return LWTUNNEL_XMIT_DONE; -- 2.40.1