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 9279BE95A98 for ; Mon, 9 Oct 2023 13:39:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377311AbjJINjh (ORCPT ); Mon, 9 Oct 2023 09:39:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377382AbjJINi4 (ORCPT ); Mon, 9 Oct 2023 09:38:56 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51AE110E for ; Mon, 9 Oct 2023 06:38:49 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F02AC433CB; Mon, 9 Oct 2023 13:38:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1696858728; bh=wE19Sfbl1wx0rX9mxUIWeAViSR6UjrFrMB7cpehj59A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KeOzvZBExXSsy6ayxqLSDZEMPmRXRNFBMpDpw+yn942NEK5uk4WXYXRjCJL5pm3Z+ aclO+tZkdjjUA/zR3C2O6BBlEPIUtLsATuRHY2p2qPy6dRUzbVtfcRilhJwfqFvhPA QHc21FkbSAH797n8jMaWlVGROBpPGJcbbNQ8mWYg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Florian Westphal , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 5.10 081/226] netfilter: exthdr: add support for tcp option removal Date: Mon, 9 Oct 2023 15:00:42 +0200 Message-ID: <20231009130128.905135223@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231009130126.697995596@linuxfoundation.org> References: <20231009130126.697995596@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Florian Westphal [ Upstream commit 7890cbea66e78a3a6037b2a12827118d7243270b ] This allows to replace a tcp option with nop padding to selectively disable a particular tcp option. Optstrip mode is chosen when userspace passes the exthdr expression with neither a source nor a destination register attribute. This is identical to xtables TCPOPTSTRIP extension. The only difference is that TCPOPTSTRIP allows to pass in a bitmap of options to remove rather than a single number. Unlike TCPOPTSTRIP this expression can be used multiple times in the same rule to get the same effect. We could add a new nested attribute later on in case there is a use case for single-expression-multi-remove. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Stable-dep-of: 28427f368f0e ("netfilter: nft_exthdr: Fix non-linear header modification") Signed-off-by: Sasha Levin --- net/netfilter/nft_exthdr.c | 96 +++++++++++++++++++++++++++++++++++++- 1 file changed, 95 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c index 10a510fef75c5..7a00867aa64ba 100644 --- a/net/netfilter/nft_exthdr.c +++ b/net/netfilter/nft_exthdr.c @@ -308,6 +308,63 @@ static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr, regs->verdict.code = NFT_BREAK; } +static void nft_exthdr_tcp_strip_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE]; + struct nft_exthdr *priv = nft_expr_priv(expr); + unsigned int i, tcphdr_len, optl; + struct tcphdr *tcph; + u8 *opt; + + tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len); + if (!tcph) + goto err; + + if (skb_ensure_writable(pkt->skb, nft_thoff(pkt) + tcphdr_len)) + goto drop; + + opt = (u8 *)nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len); + if (!opt) + goto err; + for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) { + unsigned int j; + + optl = optlen(opt, i); + if (priv->type != opt[i]) + continue; + + if (i + optl > tcphdr_len) + goto drop; + + for (j = 0; j < optl; ++j) { + u16 n = TCPOPT_NOP; + u16 o = opt[i+j]; + + if ((i + j) % 2 == 0) { + o <<= 8; + n <<= 8; + } + inet_proto_csum_replace2(&tcph->check, pkt->skb, htons(o), + htons(n), false); + } + memset(opt + i, TCPOPT_NOP, optl); + return; + } + + /* option not found, continue. This allows to do multiple + * option removals per rule. + */ + return; +err: + regs->verdict.code = NFT_BREAK; + return; +drop: + /* can't remove, no choice but to drop */ + regs->verdict.code = NF_DROP; +} + static void nft_exthdr_sctp_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) @@ -452,6 +509,28 @@ static int nft_exthdr_tcp_set_init(const struct nft_ctx *ctx, priv->len); } +static int nft_exthdr_tcp_strip_init(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_exthdr *priv = nft_expr_priv(expr); + + if (tb[NFTA_EXTHDR_SREG] || + tb[NFTA_EXTHDR_DREG] || + tb[NFTA_EXTHDR_FLAGS] || + tb[NFTA_EXTHDR_OFFSET] || + tb[NFTA_EXTHDR_LEN]) + return -EINVAL; + + if (!tb[NFTA_EXTHDR_TYPE]) + return -EINVAL; + + priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]); + priv->op = NFT_EXTHDR_OP_TCPOPT; + + return 0; +} + static int nft_exthdr_ipv4_init(const struct nft_ctx *ctx, const struct nft_expr *expr, const struct nlattr * const tb[]) @@ -512,6 +591,13 @@ static int nft_exthdr_dump_set(struct sk_buff *skb, const struct nft_expr *expr) return nft_exthdr_dump_common(skb, priv); } +static int nft_exthdr_dump_strip(struct sk_buff *skb, const struct nft_expr *expr) +{ + const struct nft_exthdr *priv = nft_expr_priv(expr); + + return nft_exthdr_dump_common(skb, priv); +} + static const struct nft_expr_ops nft_exthdr_ipv6_ops = { .type = &nft_exthdr_type, .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), @@ -544,6 +630,14 @@ static const struct nft_expr_ops nft_exthdr_tcp_set_ops = { .dump = nft_exthdr_dump_set, }; +static const struct nft_expr_ops nft_exthdr_tcp_strip_ops = { + .type = &nft_exthdr_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), + .eval = nft_exthdr_tcp_strip_eval, + .init = nft_exthdr_tcp_strip_init, + .dump = nft_exthdr_dump_strip, +}; + static const struct nft_expr_ops nft_exthdr_sctp_ops = { .type = &nft_exthdr_type, .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), @@ -571,7 +665,7 @@ nft_exthdr_select_ops(const struct nft_ctx *ctx, return &nft_exthdr_tcp_set_ops; if (tb[NFTA_EXTHDR_DREG]) return &nft_exthdr_tcp_ops; - break; + return &nft_exthdr_tcp_strip_ops; case NFT_EXTHDR_OP_IPV6: if (tb[NFTA_EXTHDR_DREG]) return &nft_exthdr_ipv6_ops; -- 2.40.1