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 14F65E743FA for ; Fri, 29 Sep 2023 08:42:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232875AbjI2ImZ (ORCPT ); Fri, 29 Sep 2023 04:42:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232841AbjI2ImW (ORCPT ); Fri, 29 Sep 2023 04:42:22 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 719B71BC for ; Fri, 29 Sep 2023 01:42:19 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1qm94j-0004jn-NO; Fri, 29 Sep 2023 10:42:17 +0200 From: Florian Westphal To: Cc: Florian Westphal , David Ward Subject: [PATCH nf] netfilter: nft_payload: rebuild vlan header on h_proto access Date: Fri, 29 Sep 2023 10:42:10 +0200 Message-ID: <20230929084213.19401-1-fw@strlen.de> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org nft can perform merging of adjacent payload requests. This means that: ether saddr 00:11 ... ether type 8021ad ... is a single payload expression, for 8 bytes, starting at the ethernet source offset. Check that offset+length is fully within the source/destination mac addersses. This bug prevents 'ether type' from matching the correct h_proto in case vlan tag got stripped. Fixes: de6843be3082 ("netfilter: nft_payload: rebuild vlan header when needed") Reported-by: David Ward Signed-off-by: Florian Westphal --- net/netfilter/nft_payload.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c index 8cb800989947..120f6d395b98 100644 --- a/net/netfilter/nft_payload.c +++ b/net/netfilter/nft_payload.c @@ -154,6 +154,17 @@ int nft_payload_inner_offset(const struct nft_pktinfo *pkt) return pkt->inneroff; } +static bool nft_payload_need_vlan_copy(const struct nft_payload *priv) +{ + unsigned int len = priv->offset + priv->len; + + /* data past ether src/dst requested, copy needed */ + if (len > offsetof(struct ethhdr, h_proto)) + return true; + + return false; +} + void nft_payload_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) @@ -172,7 +183,7 @@ void nft_payload_eval(const struct nft_expr *expr, goto err; if (skb_vlan_tag_present(skb) && - priv->offset >= offsetof(struct ethhdr, h_proto)) { + nft_payload_need_vlan_copy(priv)) { if (!nft_payload_copy_vlan(dest, skb, priv->offset, priv->len)) goto err; -- 2.41.0