tcp: fix syncookie regression
commit ea4fc0d619
(ipv4: Don't use rt->rt_{src,dst} in ip_queue_xmit())
added a serious regression on synflood handling.
Simon Kirby discovered a successful connection was delayed by 20 seconds
before being responsive.
In my tests, I discovered that xmit frames were lost, and needed ~4
retransmits and a socket dst rebuild before being really sent.
In case of syncookie initiated connection, we use a different path to
initialize the socket dst, and inet->cork.fl.u.ip4 is left cleared.
As ip_queue_xmit() now depends on inet flow being setup, fix this by
copying the temp flowi4 we use in cookie_v4_check().
Reported-by: Simon Kirby <sim@netnation.com>
Bisected-by: Simon Kirby <sim@netnation.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
4e50391968
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dfd25ffffc
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@ -278,6 +278,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
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struct rtable *rt;
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__u8 rcv_wscale;
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bool ecn_ok = false;
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struct flowi4 fl4;
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if (!sysctl_tcp_syncookies || !th->ack || th->rst)
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goto out;
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@ -346,20 +347,16 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
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* hasn't changed since we received the original syn, but I see
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* no easy way to do this.
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*/
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{
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struct flowi4 fl4;
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flowi4_init_output(&fl4, 0, sk->sk_mark, RT_CONN_FLAGS(sk),
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RT_SCOPE_UNIVERSE, IPPROTO_TCP,
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inet_sk_flowi_flags(sk),
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(opt && opt->srr) ? opt->faddr : ireq->rmt_addr,
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ireq->loc_addr, th->source, th->dest);
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security_req_classify_flow(req, flowi4_to_flowi(&fl4));
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rt = ip_route_output_key(sock_net(sk), &fl4);
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if (IS_ERR(rt)) {
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reqsk_free(req);
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goto out;
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}
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flowi4_init_output(&fl4, 0, sk->sk_mark, RT_CONN_FLAGS(sk),
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RT_SCOPE_UNIVERSE, IPPROTO_TCP,
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inet_sk_flowi_flags(sk),
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(opt && opt->srr) ? opt->faddr : ireq->rmt_addr,
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ireq->loc_addr, th->source, th->dest);
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security_req_classify_flow(req, flowi4_to_flowi(&fl4));
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rt = ip_route_output_key(sock_net(sk), &fl4);
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if (IS_ERR(rt)) {
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reqsk_free(req);
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goto out;
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}
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/* Try to redo what tcp_v4_send_synack did. */
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@ -373,5 +370,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
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ireq->rcv_wscale = rcv_wscale;
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ret = get_cookie_sock(sk, skb, req, &rt->dst);
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/* ip_queue_xmit() depends on our flow being setup
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* Normal sockets get it right from inet_csk_route_child_sock()
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*/
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if (ret)
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inet_sk(ret)->cork.fl.u.ip4 = fl4;
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out: return ret;
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}
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@ -1466,9 +1466,13 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
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inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
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newinet->inet_id = newtp->write_seq ^ jiffies;
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if (!dst && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
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goto put_and_exit;
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if (!dst) {
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dst = inet_csk_route_child_sock(sk, newsk, req);
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if (!dst)
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goto put_and_exit;
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} else {
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/* syncookie case : see end of cookie_v4_check() */
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}
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sk_setup_caps(newsk, dst);
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tcp_mtup_init(newsk);
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