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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
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/net/inet_timewait_sock.h
View file

@ -62,6 +62,7 @@ struct inet_timewait_sock {
#define tw_dr __tw_common.skc_tw_dr
int tw_timeout;
__u32 tw_mark;
volatile unsigned char tw_substate;
unsigned char tw_rcv_wscale;

2
net/ipv4/ip_output.c
View file

@ -1561,7 +1561,7 @@ void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
oif = skb->skb_iif;
flowi4_init_output(&fl4, oif,
IP4_REPLY_MARK(net, skb->mark),
IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
RT_TOS(arg->tos),
RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
ip_reply_arg_flowi_flags(arg),

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();
}

1
net/ipv4/tcp_minisocks.c
View file

@ -263,6 +263,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
struct inet_sock *inet = inet_sk(sk);
tw->tw_transparent = inet->transparent;
tw->tw_mark = sk->sk_mark;
tw->tw_rcv_wscale = tp->rx_opt.rcv_wscale;
tcptw->tw_rcv_nxt = tp->rcv_nxt;
tcptw->tw_snd_nxt = tp->snd_nxt;

6
net/ipv6/tcp_ipv6.c
View file

@ -803,6 +803,7 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
unsigned int tot_len = sizeof(struct tcphdr);
struct dst_entry *dst;
__be32 *topt;
__u32 mark = 0;
if (tsecr)
tot_len += TCPOLEN_TSTAMP_ALIGNED;
@ -871,7 +872,10 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
fl6.flowi6_oif = oif;
}
fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark);
if (sk)
mark = (sk->sk_state == TCP_TIME_WAIT) ?
inet_twsk(sk)->tw_mark : sk->sk_mark;
fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark) ?: mark;
fl6.fl6_dport = t1->dest;
fl6.fl6_sport = t1->source;
fl6.flowi6_uid = sock_net_uid(net, sk && sk_fullsock(sk) ? sk : NULL);