kernel/include/net/inet_connection_sock.h, branch linux-5.11.y

tcp: relookup sock for RST+ACK packets handled by obsolete req sock

2021-03-30T12:30:20Z

[ Upstream commit 7233da86697efef41288f8b713c10c2499cffe85 ] Currently tcp_check_req can be called with obsolete req socket for which big socket have been already created (because of CPU race or early demux assigning req socket to multiple packets in gro batch). Commit e0f9759f530bf789e984 ("tcp: try to keep packet if SYN_RCV race is lost") added retry in case when tcp_check_req is called for PSH|ACK packet. But if client sends RST+ACK immediatly after connection being established (it is performing healthcheck, for example) retry does not occur. In that case tcp_check_req tries to close req socket, leaving big socket active. Fixes: e0f9759f530 ("tcp: try to keep packet if SYN_RCV race is lost") Signed-off-by: Alexander Ovechkin Reported-by: Oleg Senin Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

tcp: fix TCP_USER_TIMEOUT with zero window

2021-01-19T03:59:17Z

The TCP session does not terminate with TCP_USER_TIMEOUT when data remain untransmitted due to zero window. The number of unanswered zero-window probes (tcp_probes_out) is reset to zero with incoming acks irrespective of the window size, as described in tcp_probe_timer(): RFC 1122 4.2.2.17 requires the sender to stay open indefinitely as long as the receiver continues to respond probes. We support this by default and reset icsk_probes_out with incoming ACKs. This counter, however, is the wrong one to be used in calculating the duration that the window remains closed and data remain untransmitted. Thanks to Jonathan Maxwell for diagnosing the actual issue. In this patch a new timestamp is introduced for the socket in order to track the elapsed time for the zero-window probes that have not been answered with any non-zero window ack. Fixes: 9721e709fa68 ("tcp: simplify window probe aborting on USER_TIMEOUT") Reported-by: William McCall Co-developed-by: Neal Cardwell Signed-off-by: Neal Cardwell Signed-off-by: Enke Chen Reviewed-by: Yuchung Cheng Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20210115223058.GA39267@localhost.localdomain Signed-off-by: Jakub Kicinski

tcp: add exponential backoff in __tcp_send_ack()

2020-09-30T21:21:30Z

Whenever host is under very high memory pressure, __tcp_send_ack() skb allocation fails, and we setup a 200 ms (TCP_DELACK_MAX) timer before retrying. On hosts with high number of TCP sockets, we can spend considerable amount of cpu cycles in these attempts, add high pressure on various spinlocks in mm-layer, ultimately blocking threads attempting to free space from making any progress. This patch adds standard exponential backoff to avoid adding fuel to the fire. Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller

inet: remove icsk_ack.blocked

2020-09-30T21:21:30Z

TCP has been using it to work around the possibility of tcp_delack_timer() finding the socket owned by user. After commit 6f458dfb4092 ("tcp: improve latencies of timer triggered events") we added TCP_DELACK_TIMER_DEFERRED atomic bit for more immediate recovery, so we can get rid of icsk_ack.blocked This frees space that following patch will reuse. Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller

tcp: Only init congestion control if not initialized already

2020-09-11T03:53:01Z

Change tcp_init_transfer() to only initialize congestion control if it has not been initialized already. With this new approach, we can arrange things so that if the EBPF code sets the congestion control by calling setsockopt(TCP_CONGESTION) then tcp_init_transfer() will not re-initialize the CC module. This is an approach that has the following beneficial properties: (1) This allows CC module customizations made by the EBPF called in tcp_init_transfer() to persist, and not be wiped out by a later call to tcp_init_congestion_control() in tcp_init_transfer(). (2) Does not flip the order of EBPF and CC init, to avoid causing bugs for existing code upstream that depends on the current order. (3) Does not cause 2 initializations for for CC in the case where the EBPF called in tcp_init_transfer() wants to set the CC to a new CC algorithm. (4) Allows follow-on simplifications to the code in net/core/filter.c and net/ipv4/tcp_cong.c, which currently both have some complexity to special-case CC initialization to avoid double CC initialization if EBPF sets the CC. Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: Alexei Starovoitov Acked-by: Yuchung Cheng Acked-by: Kevin Yang Cc: Lawrence Brakmo

tcp: bpf: Add TCP_BPF_RTO_MIN for bpf_setsockopt

2020-08-24T21:35:00Z

This patch adds bpf_setsockopt(TCP_BPF_RTO_MIN) to allow bpf prog to set the min rto of a connection. It could be used together with the earlier patch which has added bpf_setsockopt(TCP_BPF_DELACK_MAX). A later selftest patch will communicate the max delay ack in a bpf tcp header option and then the receiving side can use bpf_setsockopt(TCP_BPF_RTO_MIN) to set a shorter rto. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Reviewed-by: Eric Dumazet Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200820190027.2884170-1-kafai@fb.com

tcp: bpf: Add TCP_BPF_DELACK_MAX setsockopt

2020-08-24T21:34:59Z

This change is mostly from an internal patch and adapts it from sysctl config to the bpf_setsockopt setup. The bpf_prog can set the max delay ack by using bpf_setsockopt(TCP_BPF_DELACK_MAX). This max delay ack can be communicated to its peer through bpf header option. The receiving peer can then use this max delay ack and set a potentially lower rto by using bpf_setsockopt(TCP_BPF_RTO_MIN) which will be introduced in the next patch. Another later selftest patch will also use it like the above to show how to write and parse bpf tcp header option. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Reviewed-by: Eric Dumazet Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200820190021.2884000-1-kafai@fb.com

net: refactor bind_bucket fastreuse into helper

2020-08-11T22:49:08Z

Refactor the fastreuse update code in inet_csk_get_port into a small helper function that can be called from other places. Acked-by: Matthieu Baerts Signed-off-by: Tim Froidcoeur Signed-off-by: David S. Miller

net: pass a sockptr_t into ->setsockopt

2020-07-24T22:41:54Z

Rework the remaining setsockopt code to pass a sockptr_t instead of a plain user pointer. This removes the last remaining set_fs(KERNEL_DS) outside of architecture specific code. Signed-off-by: Christoph Hellwig Acked-by: Stefan Schmidt [ieee802154] Acked-by: Matthieu Baerts Signed-off-by: David S. Miller

net/ipv6: remove compat_ipv6_{get,set}sockopt

2020-07-20T01:16:41Z

Handle the few cases that need special treatment in-line using in_compat_syscall(). This also removes all the now unused compat_{get,set}sockopt methods. Signed-off-by: Christoph Hellwig Signed-off-by: David S. Miller