From patchwork Wed Aug 17 14:00:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Westphal X-Patchwork-Id: 12945928 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 1D0B4C28B2B for ; Wed, 17 Aug 2022 14:02:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236051AbiHQOCI (ORCPT ); Wed, 17 Aug 2022 10:02:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239974AbiHQOBa (ORCPT ); Wed, 17 Aug 2022 10:01:30 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF1E598D2E; Wed, 17 Aug 2022 07:01:16 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1oOJbf-0008Pi-29; Wed, 17 Aug 2022 16:01:15 +0200 From: Florian Westphal To: netdev@vger.kernel.org Cc: , Pablo Neira Ayuso , Paolo Abeni , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Florian Westphal Subject: [PATCH net 06/17] netfilter: nf_ct_ftp: prefer skb_linearize Date: Wed, 17 Aug 2022 16:00:04 +0200 Message-Id: <20220817140015.25843-7-fw@strlen.de> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220817140015.25843-1-fw@strlen.de> References: <20220817140015.25843-1-fw@strlen.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org This uses a pseudo-linearization scheme with a 64k global buffer, but BIG TCP arrival means IPv6 TCP stack can generate skbs that exceed this size. Use skb_linearize. It should be possible to rewrite this to properly deal with segmented skbs (i.e., only do small chunk-wise accesses), but this is going to be a lot more intrusive than this because every helper function needs to get the sk_buff instead of a pointer to a raw data buffer. In practice, provided we're really looking at FTP control channel packets, there should never be a case where we deal with huge packets. Fixes: 7c4e983c4f3c ("net: allow gso_max_size to exceed 65536") Fixes: 0fe79f28bfaf ("net: allow gro_max_size to exceed 65536") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_ftp.c | 24 ++++++------------------ 1 file changed, 6 insertions(+), 18 deletions(-) diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c index a414274338cf..0d9332e9cf71 100644 --- a/net/netfilter/nf_conntrack_ftp.c +++ b/net/netfilter/nf_conntrack_ftp.c @@ -34,11 +34,6 @@ MODULE_DESCRIPTION("ftp connection tracking helper"); MODULE_ALIAS("ip_conntrack_ftp"); MODULE_ALIAS_NFCT_HELPER(HELPER_NAME); -/* This is slow, but it's simple. --RR */ -static char *ftp_buffer; - -static DEFINE_SPINLOCK(nf_ftp_lock); - #define MAX_PORTS 8 static u_int16_t ports[MAX_PORTS]; static unsigned int ports_c; @@ -398,6 +393,9 @@ static int help(struct sk_buff *skb, return NF_ACCEPT; } + if (unlikely(skb_linearize(skb))) + return NF_DROP; + th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); if (th == NULL) return NF_ACCEPT; @@ -411,12 +409,8 @@ static int help(struct sk_buff *skb, } datalen = skb->len - dataoff; - spin_lock_bh(&nf_ftp_lock); - fb_ptr = skb_header_pointer(skb, dataoff, datalen, ftp_buffer); - if (!fb_ptr) { - spin_unlock_bh(&nf_ftp_lock); - return NF_ACCEPT; - } + spin_lock_bh(&ct->lock); + fb_ptr = skb->data + dataoff; ends_in_nl = (fb_ptr[datalen - 1] == '\n'); seq = ntohl(th->seq) + datalen; @@ -544,7 +538,7 @@ static int help(struct sk_buff *skb, if (ends_in_nl) update_nl_seq(ct, seq, ct_ftp_info, dir, skb); out: - spin_unlock_bh(&nf_ftp_lock); + spin_unlock_bh(&ct->lock); return ret; } @@ -571,7 +565,6 @@ static const struct nf_conntrack_expect_policy ftp_exp_policy = { static void __exit nf_conntrack_ftp_fini(void) { nf_conntrack_helpers_unregister(ftp, ports_c * 2); - kfree(ftp_buffer); } static int __init nf_conntrack_ftp_init(void) @@ -580,10 +573,6 @@ static int __init nf_conntrack_ftp_init(void) NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_ftp_master)); - ftp_buffer = kmalloc(65536, GFP_KERNEL); - if (!ftp_buffer) - return -ENOMEM; - if (ports_c == 0) ports[ports_c++] = FTP_PORT; @@ -603,7 +592,6 @@ static int __init nf_conntrack_ftp_init(void) ret = nf_conntrack_helpers_register(ftp, ports_c * 2); if (ret < 0) { pr_err("failed to register helpers\n"); - kfree(ftp_buffer); return ret; }