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Groups > linux.kernel > #1710047

[PATCH 4.12 14/17] udp: consistently apply ufo or fragmentation

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.12 14/17] udp: consistently apply ufo or fragmentation
Date 2017-08-12 00:20 +0200
Message-ID <udqrF-Hs-27@gated-at.bofh.it> (permalink)
References <udqhX-E7-7@gated-at.bofh.it>
Organization linux.* mail to news gateway

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4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Willem de Bruijn <willemb@google.com>


[ Upstream commit 85f1bd9a7b5a79d5baa8bf44af19658f7bf77bfa ]

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 <andreyknvl@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/ip_output.c  |    8 +++++---
 net/ipv4/udp.c        |    2 +-
 net/ipv6/ip6_output.c |    7 ++++---
 3 files changed, 10 insertions(+), 7 deletions(-)

--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -964,11 +964,12 @@ static int __ip_append_data(struct sock
 		csummode = CHECKSUM_PARTIAL;
 
 	cork->length += length;
-	if ((((length + (skb ? skb->len : fragheaderlen)) > mtu) ||
-	     (skb && skb_is_gso(skb))) &&
+	if ((skb && skb_is_gso(skb)) ||
+	    (((length + (skb ? skb->len : fragheaderlen)) > 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_no_check_tx) {
+	    (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx)) {
 		err = ip_ufo_append_data(sk, queue, getfrag, from, length,
 					 hh_len, fragheaderlen, transhdrlen,
 					 maxfraglen, flags);
@@ -1287,6 +1288,7 @@ ssize_t	ip_append_page(struct sock *sk,
 		return -EINVAL;
 
 	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)) {
 		if (skb->ip_summed != CHECKSUM_PARTIAL)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -802,7 +802,7 @@ 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
@@ -1386,11 +1386,12 @@ emsgsize:
 	 */
 
 	cork->length += length;
-	if ((((length + (skb ? skb->len : headersize)) > mtu) ||
-	     (skb && skb_is_gso(skb))) &&
+	if ((skb && skb_is_gso(skb)) ||
+	    (((length + (skb ? skb->len : headersize)) > 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) && !udp_get_no_check6_tx(sk)) {
+	    (sk->sk_type == SOCK_DGRAM) && !udp_get_no_check6_tx(sk))) {
 		err = ip6_ufo_append_data(sk, queue, getfrag, from, length,
 					  hh_len, fragheaderlen, exthdrlen,
 					  transhdrlen, mtu, flags, fl6);

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Thread

[PATCH 4.12 00/17] 4.12.7-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:10 +0200
  [PATCH 4.12 12/17] net: avoid skb_warn_bad_offload false positives on UFO Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 06/17] bpf, s390: fix jit branch offset related to ldimm64 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 15/17] packet: fix tp_reserve race in packet_set_ring Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 08/17] net: sched: set xt_tgchk_param par.net properly in ipt_init_target Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 14/17] udp: consistently apply ufo or fragmentation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 09/17] net: sched: set xt_tgchk_param par.nft_compat as 0 in ipt_init_target Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 16/17] scsi: sg: only check for dxfer_len greater than 256M Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 05/17] ipv6: set rt6i_protocol properly in the route when it is installed Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 10/17] tcp: fastopen: tcp_connect() must refresh the route Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 04/17] net: fix keepalive code vs TCP_FASTOPEN_CONNECT Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 07/17] net/mlx4_en: dont set CHECKSUM_COMPLETE on SCTP packets Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 02/17] ppp: fix xmit recursion detection on ppp channels Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  [PATCH 4.12 03/17] tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 00:20 +0200
  Re: [PATCH 4.12 00/17] 4.12.7-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-08-12 04:00 +0200
    Re: [PATCH 4.12 00/17] 4.12.7-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 16:40 +0200
  Re: [PATCH 4.12 00/17] 4.12.7-stable review Guenter Roeck <linux@roeck-us.net> - 2017-08-12 14:30 +0200
    Re: [PATCH 4.12 00/17] 4.12.7-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-12 18:10 +0200

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