Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753040AbdHRNYd (ORCPT ); Fri, 18 Aug 2017 09:24:33 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55682 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752908AbdHRNPx (ORCPT ); Fri, 18 Aug 2017 09:15:53 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Willem de Bruijn" , "Andrey Konovalov" , "David S. Miller" Date: Fri, 18 Aug 2017 14:13:20 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 134/134] udp: consistently apply ufo or fragmentation In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3323 Lines: 91 3.16.47-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Willem de Bruijn commit 85f1bd9a7b5a79d5baa8bf44af19658f7bf77bfa upstream. When iteratively building a UDP datagram with MSG_MORE and that datagram exceeds MTU, consistently choose UFO or fragmentation. Once skb_is_gso, always apply ufo. Conversely, once a datagram is split across multiple skbs, do not consider ufo. Sendpage already maintains the first invariant, only add the second. IPv6 does not have a sendpage implementation to modify. A gso skb must have a partial checksum, do not follow sk_no_check_tx in udp_send_skb. Found by syzkaller. Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach") Reported-by: Andrey Konovalov Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: - ip6_append_data() doesn't take a queue parameter; use &sk->sk_write_queue - Adjust context] Signed-off-by: Ben Hutchings --- net/ipv4/ip_output.c | 7 +++++-- net/ipv4/udp.c | 2 +- net/ipv6/ip6_output.c | 7 ++++--- 3 files changed, 10 insertions(+), 6 deletions(-) --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -885,10 +885,12 @@ static int __ip_append_data(struct sock csummode = CHECKSUM_PARTIAL; cork->length += length; - if (((length > mtu) || (skb && skb_is_gso(skb))) && + if ((skb && skb_is_gso(skb)) || + ((length > mtu) && + (skb_queue_len(queue) <= 1) && (sk->sk_protocol == IPPROTO_UDP) && (rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) && - (sk->sk_type == SOCK_DGRAM)) { + (sk->sk_type == SOCK_DGRAM))) { err = ip_ufo_append_data(sk, queue, getfrag, from, length, hh_len, fragheaderlen, transhdrlen, maxfraglen, flags); @@ -1203,6 +1205,7 @@ ssize_t ip_append_page(struct sock *sk, cork->length += size; if ((size + skb->len > mtu) && + (skb_queue_len(&sk->sk_write_queue) == 1) && (sk->sk_protocol == IPPROTO_UDP) && (rt->dst.dev->features & NETIF_F_UFO)) { skb_shinfo(skb)->gso_size = mtu - fragheaderlen; --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -824,7 +824,7 @@ static int udp_send_skb(struct sk_buff * if (is_udplite) /* UDP-Lite */ csum = udplite_csum(skb); - else if (sk->sk_no_check_tx) { /* UDP csum disabled */ + else if (sk->sk_no_check_tx && !skb_is_gso(skb)) { /* UDP csum off */ skb->ip_summed = CHECKSUM_NONE; goto send; --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1291,11 +1291,12 @@ emsgsize: skb = skb_peek_tail(&sk->sk_write_queue); cork->length += length; - if ((((length + fragheaderlen) > mtu) || - (skb && skb_is_gso(skb))) && + if ((skb && skb_is_gso(skb)) || + (((length + fragheaderlen) > mtu) && + (skb_queue_len(&sk->sk_write_queue) <= 1) && (sk->sk_protocol == IPPROTO_UDP) && (rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) && - (sk->sk_type == SOCK_DGRAM)) { + (sk->sk_type == SOCK_DGRAM))) { err = ip6_ufo_append_data(sk, getfrag, from, length, hh_len, fragheaderlen, exthdrlen, transhdrlen, mtu, flags, rt);