tcp: make retransmitted SKB fit into the send window
[ Upstream commit 536a6c8e05f95e3d1118c40ae8b3022ee2d05d52 ]
current code of __tcp_retransmit_skb only check TCP_SKB_CB(skb)->seq
in send window, and TCP_SKB_CB(skb)->seq_end maybe out of send window.
If receiver has shrunk his window, and skb is out of new window, it
should retransmit a smaller portion of the payload.
test packetdrill script:
0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0 fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
+0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
+0 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)
+0 > S 0:0(0) win 65535 <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
+.05 < S. 0:0(0) ack 1 win 6000 <mss 1000,nop,nop,sackOK>
+0 > . 1:1(0) ack 1
+0 write(3, ..., 10000) = 10000
+0 > . 1:2001(2000) ack 1 win 65535
+0 > . 2001:4001(2000) ack 1 win 65535
+0 > . 4001:6001(2000) ack 1 win 65535
+.05 < . 1:1(0) ack 4001 win 1001
and tcpdump show:
192.168.226.67.55 > 192.0.2.1.8080: Flags [.], seq 1:2001, ack 1, win 65535, length 2000
192.168.226.67.55 > 192.0.2.1.8080: Flags [.], seq 2001:4001, ack 1, win 65535, length 2000
192.168.226.67.55 > 192.0.2.1.8080: Flags [P.], seq 4001:5001, ack 1, win 65535, length 1000
192.168.226.67.55 > 192.0.2.1.8080: Flags [.], seq 5001:6001, ack 1, win 65535, length 1000
192.0.2.1.8080 > 192.168.226.67.55: Flags [.], ack 4001, win 1001, length 0
192.168.226.67.55 > 192.0.2.1.8080: Flags [.], seq 5001:6001, ack 1, win 65535, length 1000
192.168.226.67.55 > 192.0.2.1.8080: Flags [P.], seq 4001:5001, ack 1, win 65535, length 1000
when cient retract window to 1001, send window is [4001,5002],
but TLP send 5001-6001 packet which is out of send window.
Fixes: 1da177e4c3
("Linux-2.6.12-rc2")
Signed-off-by: Yonglong Li <liyonglong@chinatelecom.cn>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/1657532838-20200-1-git-send-email-liyonglong@chinatelecom.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
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@ -2911,7 +2911,7 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
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struct tcp_sock *tp = tcp_sk(sk);
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struct tcp_sock *tp = tcp_sk(sk);
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unsigned int cur_mss;
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unsigned int cur_mss;
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int diff, len, err;
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int diff, len, err;
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int avail_wnd;
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/* Inconclusive MTU probe */
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/* Inconclusive MTU probe */
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if (icsk->icsk_mtup.probe_size)
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if (icsk->icsk_mtup.probe_size)
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@ -2941,17 +2941,25 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
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return -EHOSTUNREACH; /* Routing failure or similar. */
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return -EHOSTUNREACH; /* Routing failure or similar. */
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cur_mss = tcp_current_mss(sk);
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cur_mss = tcp_current_mss(sk);
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avail_wnd = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
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/* If receiver has shrunk his window, and skb is out of
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/* If receiver has shrunk his window, and skb is out of
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* new window, do not retransmit it. The exception is the
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* new window, do not retransmit it. The exception is the
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* case, when window is shrunk to zero. In this case
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* case, when window is shrunk to zero. In this case
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* our retransmit serves as a zero window probe.
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* our retransmit of one segment serves as a zero window probe.
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*/
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*/
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if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) &&
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if (avail_wnd <= 0) {
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TCP_SKB_CB(skb)->seq != tp->snd_una)
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if (TCP_SKB_CB(skb)->seq != tp->snd_una)
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return -EAGAIN;
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return -EAGAIN;
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avail_wnd = cur_mss;
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}
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len = cur_mss * segs;
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len = cur_mss * segs;
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if (len > avail_wnd) {
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len = rounddown(avail_wnd, cur_mss);
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if (!len)
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len = avail_wnd;
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}
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if (skb->len > len) {
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if (skb->len > len) {
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if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len,
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if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len,
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cur_mss, GFP_ATOMIC))
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cur_mss, GFP_ATOMIC))
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@ -2965,8 +2973,9 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
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diff -= tcp_skb_pcount(skb);
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diff -= tcp_skb_pcount(skb);
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if (diff)
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if (diff)
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tcp_adjust_pcount(sk, skb, diff);
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tcp_adjust_pcount(sk, skb, diff);
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if (skb->len < cur_mss)
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avail_wnd = min_t(int, avail_wnd, cur_mss);
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tcp_retrans_try_collapse(sk, skb, cur_mss);
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if (skb->len < avail_wnd)
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tcp_retrans_try_collapse(sk, skb, avail_wnd);
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}
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}
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/* RFC3168, section 6.1.1.1. ECN fallback */
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/* RFC3168, section 6.1.1.1. ECN fallback */
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