95 lines
3.6 KiB
Diff
95 lines
3.6 KiB
Diff
From: Willem de Bruijn <willemb@google.com>
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Date: Thu, 10 Aug 2017 12:29:19 -0400
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Subject: udp: consistently apply ufo or fragmentation
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Origin: https://git.kernel.org/linus/85f1bd9a7b5a79d5baa8bf44af19658f7bf77bfa
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-1000112
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When iteratively building a UDP datagram with MSG_MORE and that
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datagram exceeds MTU, consistently choose UFO or fragmentation.
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Once skb_is_gso, always apply ufo. Conversely, once a datagram is
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split across multiple skbs, do not consider ufo.
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Sendpage already maintains the first invariant, only add the second.
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IPv6 does not have a sendpage implementation to modify.
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A gso skb must have a partial checksum, do not follow sk_no_check_tx
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in udp_send_skb.
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Found by syzkaller.
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Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach")
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Reported-by: Andrey Konovalov <andreyknvl@google.com>
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Signed-off-by: Willem de Bruijn <willemb@google.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/ipv4/ip_output.c | 8 +++++---
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net/ipv4/udp.c | 2 +-
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net/ipv6/ip6_output.c | 7 ++++---
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3 files changed, 10 insertions(+), 7 deletions(-)
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diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
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index 50c74cd890bc..e153c40c2436 100644
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--- a/net/ipv4/ip_output.c
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+++ b/net/ipv4/ip_output.c
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@@ -965,11 +965,12 @@ static int __ip_append_data(struct sock *sk,
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csummode = CHECKSUM_PARTIAL;
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cork->length += length;
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- if ((((length + (skb ? skb->len : fragheaderlen)) > mtu) ||
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- (skb && skb_is_gso(skb))) &&
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+ if ((skb && skb_is_gso(skb)) ||
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+ (((length + (skb ? skb->len : fragheaderlen)) > mtu) &&
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+ (skb_queue_len(queue) <= 1) &&
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(sk->sk_protocol == IPPROTO_UDP) &&
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(rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) &&
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- (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx) {
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+ (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx)) {
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err = ip_ufo_append_data(sk, queue, getfrag, from, length,
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hh_len, fragheaderlen, transhdrlen,
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maxfraglen, flags);
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@@ -1288,6 +1289,7 @@ ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
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return -EINVAL;
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if ((size + skb->len > mtu) &&
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+ (skb_queue_len(&sk->sk_write_queue) == 1) &&
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(sk->sk_protocol == IPPROTO_UDP) &&
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(rt->dst.dev->features & NETIF_F_UFO)) {
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if (skb->ip_summed != CHECKSUM_PARTIAL)
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diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
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index e6276fa3750b..a7c804f73990 100644
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--- a/net/ipv4/udp.c
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+++ b/net/ipv4/udp.c
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@@ -802,7 +802,7 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4)
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if (is_udplite) /* UDP-Lite */
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csum = udplite_csum(skb);
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- else if (sk->sk_no_check_tx) { /* UDP csum disabled */
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+ else if (sk->sk_no_check_tx && !skb_is_gso(skb)) { /* UDP csum off */
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skb->ip_summed = CHECKSUM_NONE;
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goto send;
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diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
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index 162efba0d0cd..2dfe50d8d609 100644
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--- a/net/ipv6/ip6_output.c
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+++ b/net/ipv6/ip6_output.c
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@@ -1381,11 +1381,12 @@ static int __ip6_append_data(struct sock *sk,
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*/
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cork->length += length;
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- if ((((length + (skb ? skb->len : headersize)) > mtu) ||
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- (skb && skb_is_gso(skb))) &&
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+ if ((skb && skb_is_gso(skb)) ||
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+ (((length + (skb ? skb->len : headersize)) > mtu) &&
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+ (skb_queue_len(queue) <= 1) &&
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(sk->sk_protocol == IPPROTO_UDP) &&
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(rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) &&
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- (sk->sk_type == SOCK_DGRAM) && !udp_get_no_check6_tx(sk)) {
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+ (sk->sk_type == SOCK_DGRAM) && !udp_get_no_check6_tx(sk))) {
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err = ip6_ufo_append_data(sk, queue, getfrag, from, length,
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hh_len, fragheaderlen, exthdrlen,
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transhdrlen, mtu, flags, fl6);
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--
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2.11.0
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