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tcp: Add mark for TIMEWAIT sockets

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This version has some suggestions by Eric Dumazet:

- Use a local variable for the mark in IPv6 instead of ctl_sk to avoid SMP
races.
- Use the more elegant "IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark"
statement.
- Factorize code as sk_fullsock() check is not necessary.

Aidan McGurn from Openwave Mobility systems reported the following bug:

"Marked routing is broken on customer deployment. Its effects are large
increase in Uplink retransmissions caused by the client never receiving
the final ACK to their FINACK - this ACK misses the mark and routes out
of the incorrect route."

Currently marks are added to sk_buffs for replies when the "fwmark_reflect"
sysctl is enabled. But not for TW sockets that had sk->sk_mark set via
setsockopt(SO_MARK..).

Fix this in IPv4/v6 by adding tw->tw_mark for TIME_WAIT sockets. Copy the the
original sk->sk_mark in __inet_twsk_hashdance() to the new tw->tw_mark location.
Then progate this so that the skb gets sent with the correct mark. Do the same
for resets. Give the "fwmark_reflect" sysctl precedence over sk->sk_mark so that
netfilter rules are still honored.

Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jon Maxwell 2018-05-10 16:53:51 +10:00 • committed by David S. Miller
parent 03bdfc001c
commit 0048369055
5 changed files with 22 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

16
net/ipv4/tcp_ipv4.c
View file

@ -621,6 +621,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
struct sock *sk1 = NULL;
#endif
struct net *net;
struct sock *ctl_sk;
/* Never send a reset in response to a reset. */
if (th->rst)
@ -723,11 +724,16 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
arg.tos = ip_hdr(skb)->tos;
arg.uid = sock_net_uid(net, sk && sk_fullsock(sk) ? sk : NULL);
local_bh_disable();
ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
ctl_sk = *this_cpu_ptr(net->ipv4.tcp_sk);
if (sk)
ctl_sk->sk_mark = (sk->sk_state == TCP_TIME_WAIT) ?
inet_twsk(sk)->tw_mark : sk->sk_mark;
ip_send_unicast_reply(ctl_sk,
skb, &TCP_SKB_CB(skb)->header.h4.opt,
ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
&arg, arg.iov[0].iov_len);
ctl_sk->sk_mark = 0;
__TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
__TCP_INC_STATS(net, TCP_MIB_OUTRSTS);
local_bh_enable();
@ -759,6 +765,7 @@ static void tcp_v4_send_ack(const struct sock *sk,
} rep;
struct net *net = sock_net(sk);
struct ip_reply_arg arg;
struct sock *ctl_sk;
memset(&rep.th, 0, sizeof(struct tcphdr));
memset(&arg, 0, sizeof(arg));
@ -809,11 +816,16 @@ static void tcp_v4_send_ack(const struct sock *sk,
arg.tos = tos;
arg.uid = sock_net_uid(net, sk_fullsock(sk) ? sk : NULL);
local_bh_disable();
ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
ctl_sk = *this_cpu_ptr(net->ipv4.tcp_sk);
if (sk)
ctl_sk->sk_mark = (sk->sk_state == TCP_TIME_WAIT) ?
inet_twsk(sk)->tw_mark : sk->sk_mark;
ip_send_unicast_reply(ctl_sk,
skb, &TCP_SKB_CB(skb)->header.h4.opt,
ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
&arg, arg.iov[0].iov_len);
ctl_sk->sk_mark = 0;
__TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
local_bh_enable();
}