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3 daystcp: fix mptcp DSS corruption due to large pmtu xmitPaolo Abeni1-3/+1
commit 4dabcdf581217e60690467a37c956a5b8dbc6bd9 upstream. Syzkaller was able to trigger a DSS corruption: TCP: request_sock_subflow_v4: Possible SYN flooding on port [::]:20002. Sending cookies. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 5227 at net/mptcp/protocol.c:695 __mptcp_move_skbs_from_subflow+0x20a9/0x21f0 net/mptcp/protocol.c:695 Modules linked in: CPU: 0 UID: 0 PID: 5227 Comm: syz-executor350 Not tainted 6.11.0-syzkaller-08829-gaf9c191ac2a0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 RIP: 0010:__mptcp_move_skbs_from_subflow+0x20a9/0x21f0 net/mptcp/protocol.c:695 Code: 0f b6 dc 31 ff 89 de e8 b5 dd ea f5 89 d8 48 81 c4 50 01 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 98 da ea f5 90 <0f> 0b 90 e9 47 ff ff ff e8 8a da ea f5 90 0f 0b 90 e9 99 e0 ff ff RSP: 0018:ffffc90000006db8 EFLAGS: 00010246 RAX: ffffffff8ba9df18 RBX: 00000000000055f0 RCX: ffff888030023c00 RDX: 0000000000000100 RSI: 00000000000081e5 RDI: 00000000000055f0 RBP: 1ffff110062bf1ae R08: ffffffff8ba9cf12 R09: 1ffff110062bf1b8 R10: dffffc0000000000 R11: ffffed10062bf1b9 R12: 0000000000000000 R13: dffffc0000000000 R14: 00000000700cec61 R15: 00000000000081e5 FS: 000055556679c380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020287000 CR3: 0000000077892000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> move_skbs_to_msk net/mptcp/protocol.c:811 [inline] mptcp_data_ready+0x29c/0xa90 net/mptcp/protocol.c:854 subflow_data_ready+0x34a/0x920 net/mptcp/subflow.c:1490 tcp_data_queue+0x20fd/0x76c0 net/ipv4/tcp_input.c:5283 tcp_rcv_established+0xfba/0x2020 net/ipv4/tcp_input.c:6237 tcp_v4_do_rcv+0x96d/0xc70 net/ipv4/tcp_ipv4.c:1915 tcp_v4_rcv+0x2dc0/0x37f0 net/ipv4/tcp_ipv4.c:2350 ip_protocol_deliver_rcu+0x22e/0x440 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x341/0x5f0 net/ipv4/ip_input.c:233 NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314 NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314 __netif_receive_skb_one_core net/core/dev.c:5662 [inline] __netif_receive_skb+0x2bf/0x650 net/core/dev.c:5775 process_backlog+0x662/0x15b0 net/core/dev.c:6107 __napi_poll+0xcb/0x490 net/core/dev.c:6771 napi_poll net/core/dev.c:6840 [inline] net_rx_action+0x89b/0x1240 net/core/dev.c:6962 handle_softirqs+0x2c5/0x980 kernel/softirq.c:554 do_softirq+0x11b/0x1e0 kernel/softirq.c:455 </IRQ> <TASK> __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline] __dev_queue_xmit+0x1764/0x3e80 net/core/dev.c:4451 dev_queue_xmit include/linux/netdevice.h:3094 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0xd41/0x1390 net/ipv4/ip_output.c:236 ip_local_out net/ipv4/ip_output.c:130 [inline] __ip_queue_xmit+0x118c/0x1b80 net/ipv4/ip_output.c:536 __tcp_transmit_skb+0x2544/0x3b30 net/ipv4/tcp_output.c:1466 tcp_transmit_skb net/ipv4/tcp_output.c:1484 [inline] tcp_mtu_probe net/ipv4/tcp_output.c:2547 [inline] tcp_write_xmit+0x641d/0x6bf0 net/ipv4/tcp_output.c:2752 __tcp_push_pending_frames+0x9b/0x360 net/ipv4/tcp_output.c:3015 tcp_push_pending_frames include/net/tcp.h:2107 [inline] tcp_data_snd_check net/ipv4/tcp_input.c:5714 [inline] tcp_rcv_established+0x1026/0x2020 net/ipv4/tcp_input.c:6239 tcp_v4_do_rcv+0x96d/0xc70 net/ipv4/tcp_ipv4.c:1915 sk_backlog_rcv include/net/sock.h:1113 [inline] __release_sock+0x214/0x350 net/core/sock.c:3072 release_sock+0x61/0x1f0 net/core/sock.c:3626 mptcp_push_release net/mptcp/protocol.c:1486 [inline] __mptcp_push_pending+0x6b5/0x9f0 net/mptcp/protocol.c:1625 mptcp_sendmsg+0x10bb/0x1b10 net/mptcp/protocol.c:1903 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x1a6/0x270 net/socket.c:745 ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2603 ___sys_sendmsg net/socket.c:2657 [inline] __sys_sendmsg+0x2aa/0x390 net/socket.c:2686 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb06e9317f9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe2cfd4f98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fb06e97f468 RCX: 00007fb06e9317f9 RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000005 RBP: 00007fb06e97f446 R08: 0000555500000000 R09: 0000555500000000 R10: 0000555500000000 R11: 0000000000000246 R12: 00007fb06e97f406 R13: 0000000000000001 R14: 00007ffe2cfd4fe0 R15: 0000000000000003 </TASK> Additionally syzkaller provided a nice reproducer. The repro enables pmtu on the loopback device, leading to tcp_mtu_probe() generating very large probe packets. tcp_can_coalesce_send_queue_head() currently does not check for mptcp-level invariants, and allowed the creation of cross-DSS probes, leading to the mentioned corruption. Address the issue teaching tcp_can_coalesce_send_queue_head() about mptcp using the tcp_skb_can_collapse(), also reducing the code duplication. Fixes: 85712484110d ("tcp: coalesce/collapse must respect MPTCP extensions") Cc: stable@vger.kernel.org Reported-by: syzbot+d1bff73460e33101f0e7@syzkaller.appspotmail.com Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/513 Signed-off-by: Paolo Abeni <pabeni@redhat.com> Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-2-c6fb8e93e551@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> [ Conflict in tcp_output.c, because the commit 65249feb6b3d ("net: add support for skbs with unreadable frags") is not in this version. This commit is linked to a new feature (Devmem TCP) and introduces a new condition which causes the conflicts. Resolving this is easy: we can ignore the missing new condition, and use tcp_skb_can_collapse() like in the original patch. ] Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-08-11tcp: annotate data-races around tp->window_clampEric Dumazet1-8/+10
[ Upstream commit f410cbea9f3d2675b4c8e52af1d1985b11b387d1 ] tp->window_clamp can be read locklessly, add READ_ONCE() and WRITE_ONCE() annotations. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> Link: https://lore.kernel.org/r/20240404114231.2195171-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Stable-dep-of: 05f76b2d634e ("tcp: Adjust clamping window for applications specifying SO_RCVBUF") Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-05-17tcp: defer shutdown(SEND_SHUTDOWN) for TCP_SYN_RECV socketsEric Dumazet1-1/+3
[ Upstream commit 94062790aedb505bdda209b10bea47b294d6394f ] TCP_SYN_RECV state is really special, it is only used by cross-syn connections, mostly used by fuzzers. In the following crash [1], syzbot managed to trigger a divide by zero in tcp_rcv_space_adjust() A socket makes the following state transitions, without ever calling tcp_init_transfer(), meaning tcp_init_buffer_space() is also not called. TCP_CLOSE connect() TCP_SYN_SENT TCP_SYN_RECV shutdown() -> tcp_shutdown(sk, SEND_SHUTDOWN) TCP_FIN_WAIT1 To fix this issue, change tcp_shutdown() to not perform a TCP_SYN_RECV -> TCP_FIN_WAIT1 transition, which makes no sense anyway. When tcp_rcv_state_process() later changes socket state from TCP_SYN_RECV to TCP_ESTABLISH, then look at sk->sk_shutdown to finally enter TCP_FIN_WAIT1 state, and send a FIN packet from a sane socket state. This means tcp_send_fin() can now be called from BH context, and must use GFP_ATOMIC allocations. [1] divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 1 PID: 5084 Comm: syz-executor358 Not tainted 6.9.0-rc6-syzkaller-00022-g98369dccd2f8 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 RIP: 0010:tcp_rcv_space_adjust+0x2df/0x890 net/ipv4/tcp_input.c:767 Code: e3 04 4c 01 eb 48 8b 44 24 38 0f b6 04 10 84 c0 49 89 d5 0f 85 a5 03 00 00 41 8b 8e c8 09 00 00 89 e8 29 c8 48 0f af c3 31 d2 <48> f7 f1 48 8d 1c 43 49 8d 96 76 08 00 00 48 89 d0 48 c1 e8 03 48 RSP: 0018:ffffc900031ef3f0 EFLAGS: 00010246 RAX: 0c677a10441f8f42 RBX: 000000004fb95e7e RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000027d4b11f R08: ffffffff89e535a4 R09: 1ffffffff25e6ab7 R10: dffffc0000000000 R11: ffffffff8135e920 R12: ffff88802a9f8d30 R13: dffffc0000000000 R14: ffff88802a9f8d00 R15: 1ffff1100553f2da FS: 00005555775c0380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1155bf2304 CR3: 000000002b9f2000 CR4: 0000000000350ef0 Call Trace: <TASK> tcp_recvmsg_locked+0x106d/0x25a0 net/ipv4/tcp.c:2513 tcp_recvmsg+0x25d/0x920 net/ipv4/tcp.c:2578 inet6_recvmsg+0x16a/0x730 net/ipv6/af_inet6.c:680 sock_recvmsg_nosec net/socket.c:1046 [inline] sock_recvmsg+0x109/0x280 net/socket.c:1068 ____sys_recvmsg+0x1db/0x470 net/socket.c:2803 ___sys_recvmsg net/socket.c:2845 [inline] do_recvmmsg+0x474/0xae0 net/socket.c:2939 __sys_recvmmsg net/socket.c:3018 [inline] __do_sys_recvmmsg net/socket.c:3041 [inline] __se_sys_recvmmsg net/socket.c:3034 [inline] __x64_sys_recvmmsg+0x199/0x250 net/socket.c:3034 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7faeb6363db9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffcc1997168 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007faeb6363db9 RDX: 0000000000000001 RSI: 0000000020000bc0 RDI: 0000000000000005 RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000001c R10: 0000000000000122 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Link: https://lore.kernel.org/r/20240501125448.896529-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-01-10tcp: derive delack_max from rto_minEric Dumazet1-1/+15
[ Upstream commit bbf80d713fe75cfbecda26e7c03a9a8d22af2f4f ] While BPF allows to set icsk->->icsk_delack_max and/or icsk->icsk_rto_min, we have an ip route attribute (RTAX_RTO_MIN) to be able to tune rto_min, but nothing to consequently adjust max delayed ack, which vary from 40ms to 200 ms (TCP_DELACK_{MIN|MAX}). This makes RTAX_RTO_MIN of almost no practical use, unless customers are in big trouble. Modern days datacenter communications want to set rto_min to ~5 ms, and the max delayed ack one jiffie smaller to avoid spurious retransmits. After this patch, an "rto_min 5" route attribute will effectively lower max delayed ack timers to 4 ms. Note in the following ss output, "rto:6 ... ato:4" $ ss -temoi dst XXXXXX State Recv-Q Send-Q Local Address:Port Peer Address:Port Process ESTAB 0 0 [2002:a05:6608:295::]:52950 [2002:a05:6608:297::]:41597 ino:255134 sk:1001 <-> skmem:(r0,rb1707063,t872,tb262144,f0,w0,o0,bl0,d0) ts sack cubic wscale:8,8 rto:6 rtt:0.02/0.002 ato:4 mss:4096 pmtu:4500 rcvmss:536 advmss:4096 cwnd:10 bytes_sent:54823160 bytes_acked:54823121 bytes_received:54823120 segs_out:1370582 segs_in:1370580 data_segs_out:1370579 data_segs_in:1370578 send 16.4Gbps pacing_rate 32.6Gbps delivery_rate 1.72Gbps delivered:1370579 busy:26920ms unacked:1 rcv_rtt:34.615 rcv_space:65920 rcv_ssthresh:65535 minrtt:0.015 snd_wnd:65536 While we could argue this patch fixes a bug with RTAX_RTO_MIN, I do not add a Fixes: tag, so that we can soak it a bit before asking backports to stable branches. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-12-20net: Remove acked SYN flag from packet in the transmit queue correctlyDong Chenchen1-0/+6
[ Upstream commit f99cd56230f56c8b6b33713c5be4da5d6766be1f ] syzkaller report: kernel BUG at net/core/skbuff.c:3452! invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.7.0-rc4-00009-gbee0e7762ad2-dirty #135 RIP: 0010:skb_copy_and_csum_bits (net/core/skbuff.c:3452) Call Trace: icmp_glue_bits (net/ipv4/icmp.c:357) __ip_append_data.isra.0 (net/ipv4/ip_output.c:1165) ip_append_data (net/ipv4/ip_output.c:1362 net/ipv4/ip_output.c:1341) icmp_push_reply (net/ipv4/icmp.c:370) __icmp_send (./include/net/route.h:252 net/ipv4/icmp.c:772) ip_fragment.constprop.0 (./include/linux/skbuff.h:1234 net/ipv4/ip_output.c:592 net/ipv4/ip_output.c:577) __ip_finish_output (net/ipv4/ip_output.c:311 net/ipv4/ip_output.c:295) ip_output (net/ipv4/ip_output.c:427) __ip_queue_xmit (net/ipv4/ip_output.c:535) __tcp_transmit_skb (net/ipv4/tcp_output.c:1462) __tcp_retransmit_skb (net/ipv4/tcp_output.c:3387) tcp_retransmit_skb (net/ipv4/tcp_output.c:3404) tcp_retransmit_timer (net/ipv4/tcp_timer.c:604) tcp_write_timer (./include/linux/spinlock.h:391 net/ipv4/tcp_timer.c:716) The panic issue was trigered by tcp simultaneous initiation. The initiation process is as follows: TCP A TCP B 1. CLOSED CLOSED 2. SYN-SENT --> <SEQ=100><CTL=SYN> ... 3. SYN-RECEIVED <-- <SEQ=300><CTL=SYN> <-- SYN-SENT 4. ... <SEQ=100><CTL=SYN> --> SYN-RECEIVED 5. SYN-RECEIVED --> <SEQ=100><ACK=301><CTL=SYN,ACK> ... // TCP B: not send challenge ack for ack limit or packet loss // TCP A: close tcp_close tcp_send_fin if (!tskb && tcp_under_memory_pressure(sk)) tskb = skb_rb_last(&sk->tcp_rtx_queue); //pick SYN_ACK packet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; // set FIN flag 6. FIN_WAIT_1 --> <SEQ=100><ACK=301><END_SEQ=102><CTL=SYN,FIN,ACK> ... // TCP B: send challenge ack to SYN_FIN_ACK 7. ... <SEQ=301><ACK=101><CTL=ACK> <-- SYN-RECEIVED //challenge ack // TCP A: <SND.UNA=101> 8. FIN_WAIT_1 --> <SEQ=101><ACK=301><END_SEQ=102><CTL=SYN,FIN,ACK> ... // retransmit panic __tcp_retransmit_skb //skb->len=0 tcp_trim_head len = tp->snd_una - TCP_SKB_CB(skb)->seq // len=101-100 __pskb_trim_head skb->data_len -= len // skb->len=-1, wrap around ... ... ip_fragment icmp_glue_bits //BUG_ON If we use tcp_trim_head() to remove acked SYN from packet that contains data or other flags, skb->len will be incorrectly decremented. We can remove SYN flag that has been acked from rtx_queue earlier than tcp_trim_head(), which can fix the problem mentioned above. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Co-developed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> Link: https://lore.kernel.org/r/20231210020200.1539875-1-dongchenchen2@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-11-28net: annotate data-races around sk->sk_dst_pending_confirmEric Dumazet1-1/+1
[ Upstream commit eb44ad4e635132754bfbcb18103f1dcb7058aedd ] This field can be read or written without socket lock being held. Add annotations to avoid load-store tearing. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-10-19tcp: tsq: relax tcp_small_queue_check() when rtx queue contains a single skbEric Dumazet1-2/+14
In commit 75eefc6c59fd ("tcp: tsq: add a shortcut in tcp_small_queue_check()") we allowed to send an skb regardless of TSQ limits being hit if rtx queue was empty or had a single skb, in order to better fill the pipe when/if TX completions were slow. Then later, commit 75c119afe14f ("tcp: implement rb-tree based retransmit queue") accidentally removed the special case for one skb in rtx queue. Stefan Wahren reported a regression in single TCP flow throughput using a 100Mbit fec link, starting from commit 65466904b015 ("tcp: adjust TSO packet sizes based on min_rtt"). This last commit only made the regression more visible, because it locked the TCP flow on a particular behavior where TSQ prevented two skbs being pushed downstream, adding silences on the wire between each TSO packet. Many thanks to Stefan for his invaluable help ! Fixes: 75c119afe14f ("tcp: implement rb-tree based retransmit queue") Link: https://lore.kernel.org/netdev/7f31ddc8-9971-495e-a1f6-819df542e0af@gmx.net/ Reported-by: Stefan Wahren <wahrenst@gmx.net> Tested-by: Stefan Wahren <wahrenst@gmx.net> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Link: https://lore.kernel.org/r/20231017124526.4060202-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-10-18tcp: fix excessive TLP and RACK timeouts from HZ roundingNeal Cardwell1-4/+5
We discovered from packet traces of slow loss recovery on kernels with the default HZ=250 setting (and min_rtt < 1ms) that after reordering, when receiving a SACKed sequence range, the RACK reordering timer was firing after about 16ms rather than the desired value of roughly min_rtt/4 + 2ms. The problem is largely due to the RACK reorder timer calculation adding in TCP_TIMEOUT_MIN, which is 2 jiffies. On kernels with HZ=250, this is 2*4ms = 8ms. The TLP timer calculation has the exact same issue. This commit fixes the TLP transmit timer and RACK reordering timer floor calculation to more closely match the intended 2ms floor even on kernels with HZ=250. It does this by adding in a new TCP_TIMEOUT_MIN_US floor of 2000 us and then converting to jiffies, instead of the current approach of converting to jiffies and then adding th TCP_TIMEOUT_MIN value of 2 jiffies. Our testing has verified that on kernels with HZ=1000, as expected, this does not produce significant changes in behavior, but on kernels with the default HZ=250 the latency improvement can be large. For example, our tests show that for HZ=250 kernels at low RTTs this fix roughly halves the latency for the RACK reorder timer: instead of mostly firing at 16ms it mostly fires at 8ms. Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Fixes: bb4d991a28cc ("tcp: adjust tail loss probe timeout") Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20231015174700.2206872-1-ncardwell.sw@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-10-12net: tcp: fix crashes trying to free half-baked MTU probesJakub Kicinski1-0/+1
tcp_stream_alloc_skb() initializes the skb to use tcp_tsorted_anchor which is a union with the destructor. We need to clean that TCP-iness up before freeing. Fixes: 736013292e3c ("tcp: let tcp_mtu_probe() build headless packets") Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20231010173651.3990234-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-10-05tcp: fix quick-ack counting to count actual ACKs of new dataNeal Cardwell1-4/+3
This commit fixes quick-ack counting so that it only considers that a quick-ack has been provided if we are sending an ACK that newly acknowledges data. The code was erroneously using the number of data segments in outgoing skbs when deciding how many quick-ack credits to remove. This logic does not make sense, and could cause poor performance in request-response workloads, like RPC traffic, where requests or responses can be multi-segment skbs. When a TCP connection decides to send N quick-acks, that is to accelerate the cwnd growth of the congestion control module controlling the remote endpoint of the TCP connection. That quick-ack decision is purely about the incoming data and outgoing ACKs. It has nothing to do with the outgoing data or the size of outgoing data. And in particular, an ACK only serves the intended purpose of allowing the remote congestion control to grow the congestion window quickly if the ACK is ACKing or SACKing new data. The fix is simple: only count packets as serving the goal of the quickack mechanism if they are ACKing/SACKing new data. We can tell whether this is the case by checking inet_csk_ack_scheduled(), since we schedule an ACK exactly when we are ACKing/SACKing new data. Fixes: fc6415bcb0f5 ("[TCP]: Fix quick-ack decrementing with TSO.") Signed-off-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20231001151239.1866845-1-ncardwell.sw@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-09-01net: annotate data-races around sk->sk_forward_allocEric Dumazet1-1/+1
Every time sk->sk_forward_alloc is read locklessly, add a READ_ONCE(). Add sk_forward_alloc_add() helper to centralize updates, to reduce number of WRITE_ONCE(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-08-19tcp: refine skb->ooo_okay settingEric Dumazet1-7/+14
Enabling BIG TCP on a low end platform apparently increased chances of getting flows locked on one busy TX queue. A similar problem was handled in commit 9b462d02d6dd ("tcp: TCP Small Queues and strange attractors"), but the strategy worked for either bulk flows, or 'large enough' RPC. BIG TCP changed how large RPC needed to be to enable the work around: If RPC fits in a single skb, TSQ never triggers. Root cause for the problem is a busy TX queue, with delayed TX completions. This patch changes how we set skb->ooo_okay to detect the case TX completion was not done, but incoming ACK already was processed and emptied rtx queue. Update the comment to explain the tricky details. Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20230817182353.2523746-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-08-13net: tcp: send zero-window ACK when no memoryMenglong Dong1-3/+11
For now, skb will be dropped when no memory, which makes client keep retrans util timeout and it's not friendly to the users. In this patch, we reply an ACK with zero-window in this case to update the snd_wnd of the sender to 0. Therefore, the sender won't timeout the connection and will probe the zero-window with the retransmits. Signed-off-by: Menglong Dong <imagedong@tencent.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-08-05tcp: Disable header prediction for MD5 flow.Kuniyuki Iwashima1-5/+0
TCP socket saves the minimum required header length in tcp_header_len of struct tcp_sock, and later the value is used in __tcp_fast_path_on() to generate a part of TCP header in tcp_sock(sk)->pred_flags. In tcp_rcv_established(), if the incoming packet has the same pattern with pred_flags, we enter the fast path and skip full option parsing. The MD5 option is parsed in tcp_v[46]_rcv(), so we need not parse it again later in tcp_rcv_established() unless other options exist. We add TCPOLEN_MD5SIG_ALIGNED to tcp_header_len in two paths to avoid the slow path. For passive open connections with MD5, we add TCPOLEN_MD5SIG_ALIGNED to tcp_header_len in tcp_create_openreq_child() after 3WHS. On the other hand, we do it in tcp_connect_init() for active open connections. However, the value is overwritten while processing SYN+ACK or crossed SYN in tcp_rcv_synsent_state_process(). These two cases will have the wrong value in pred_flags and never go into the fast path. We could update tcp_header_len in tcp_rcv_synsent_state_process(), but a test with slightly modified netperf which uses MD5 for each flow shows that the slow path is actually a bit faster than the fast path. On c5.4xlarge EC2 instance (16 vCPU, 32 GiB mem) $ for i in {1..10}; do ./super_netperf $(nproc) -H localhost -l 10 -- -m 256 -M 256; done Avg of 10 * 36e68eadd303 : 10.376 Gbps * all fast path : 10.374 Gbps (patch v2, See Link) * all slow path : 10.394 Gbps The header prediction is not worth adding complexity for MD5, so let's disable it for MD5. Link: https://lore.kernel.org/netdev/20230803042214.38309-1-kuniyu@amazon.com/ Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20230803224552.69398-2-kuniyu@amazon.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-07-19tcp: annotate data-races around tcp_rsk(req)->ts_recentEric Dumazet1-1/+1
TCP request sockets are lockless, tcp_rsk(req)->ts_recent can change while being read by another cpu as syzbot noticed. This is harmless, but we should annotate the known races. Note that tcp_check_req() changes req->ts_recent a bit early, we might change this in the future. BUG: KCSAN: data-race in tcp_check_req / tcp_check_req write to 0xffff88813c8afb84 of 4 bytes by interrupt on cpu 1: tcp_check_req+0x694/0xc70 net/ipv4/tcp_minisocks.c:762 tcp_v4_rcv+0x12db/0x1b70 net/ipv4/tcp_ipv4.c:2071 ip_protocol_deliver_rcu+0x356/0x6d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x13c/0x1a0 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:303 [inline] ip_local_deliver+0xec/0x1c0 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:468 [inline] ip_rcv_finish net/ipv4/ip_input.c:449 [inline] NF_HOOK include/linux/netfilter.h:303 [inline] ip_rcv+0x197/0x270 net/ipv4/ip_input.c:569 __netif_receive_skb_one_core net/core/dev.c:5493 [inline] __netif_receive_skb+0x90/0x1b0 net/core/dev.c:5607 process_backlog+0x21f/0x380 net/core/dev.c:5935 __napi_poll+0x60/0x3b0 net/core/dev.c:6498 napi_poll net/core/dev.c:6565 [inline] net_rx_action+0x32b/0x750 net/core/dev.c:6698 __do_softirq+0xc1/0x265 kernel/softirq.c:571 do_softirq+0x7e/0xb0 kernel/softirq.c:472 __local_bh_enable_ip+0x64/0x70 kernel/softirq.c:396 local_bh_enable+0x1f/0x20 include/linux/bottom_half.h:33 rcu_read_unlock_bh include/linux/rcupdate.h:843 [inline] __dev_queue_xmit+0xabb/0x1d10 net/core/dev.c:4271 dev_queue_xmit include/linux/netdevice.h:3088 [inline] neigh_hh_output include/net/neighbour.h:528 [inline] neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0x700/0x840 net/ipv4/ip_output.c:229 ip_finish_output+0xf4/0x240 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:292 [inline] ip_output+0xe5/0x1b0 net/ipv4/ip_output.c:431 dst_output include/net/dst.h:458 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] __ip_queue_xmit+0xa4d/0xa70 net/ipv4/ip_output.c:533 ip_queue_xmit+0x38/0x40 net/ipv4/ip_output.c:547 __tcp_transmit_skb+0x1194/0x16e0 net/ipv4/tcp_output.c:1399 tcp_transmit_skb net/ipv4/tcp_output.c:1417 [inline] tcp_write_xmit+0x13ff/0x2fd0 net/ipv4/tcp_output.c:2693 __tcp_push_pending_frames+0x6a/0x1a0 net/ipv4/tcp_output.c:2877 tcp_push_pending_frames include/net/tcp.h:1952 [inline] __tcp_sock_set_cork net/ipv4/tcp.c:3336 [inline] tcp_sock_set_cork+0xe8/0x100 net/ipv4/tcp.c:3343 rds_tcp_xmit_path_complete+0x3b/0x40 net/rds/tcp_send.c:52 rds_send_xmit+0xf8d/0x1420 net/rds/send.c:422 rds_send_worker+0x42/0x1d0 net/rds/threads.c:200 process_one_work+0x3e6/0x750 kernel/workqueue.c:2408 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2555 kthread+0x1d7/0x210 kernel/kthread.c:379 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 read to 0xffff88813c8afb84 of 4 bytes by interrupt on cpu 0: tcp_check_req+0x32a/0xc70 net/ipv4/tcp_minisocks.c:622 tcp_v4_rcv+0x12db/0x1b70 net/ipv4/tcp_ipv4.c:2071 ip_protocol_deliver_rcu+0x356/0x6d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x13c/0x1a0 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:303 [inline] ip_local_deliver+0xec/0x1c0 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:468 [inline] ip_rcv_finish net/ipv4/ip_input.c:449 [inline] NF_HOOK include/linux/netfilter.h:303 [inline] ip_rcv+0x197/0x270 net/ipv4/ip_input.c:569 __netif_receive_skb_one_core net/core/dev.c:5493 [inline] __netif_receive_skb+0x90/0x1b0 net/core/dev.c:5607 process_backlog+0x21f/0x380 net/core/dev.c:5935 __napi_poll+0x60/0x3b0 net/core/dev.c:6498 napi_poll net/core/dev.c:6565 [inline] net_rx_action+0x32b/0x750 net/core/dev.c:6698 __do_softirq+0xc1/0x265 kernel/softirq.c:571 run_ksoftirqd+0x17/0x20 kernel/softirq.c:939 smpboot_thread_fn+0x30a/0x4a0 kernel/smpboot.c:164 kthread+0x1d7/0x210 kernel/kthread.c:379 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 value changed: 0x1cd237f1 -> 0x1cd237f2 Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://lore.kernel.org/r/20230717144445.653164-3-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-07-19tcp: annotate data-races around tcp_rsk(req)->txhashEric Dumazet1-2/+2
TCP request sockets are lockless, some of their fields can change while being read by another cpu as syzbot noticed. This is usually harmless, but we should annotate the known races. This patch takes care of tcp_rsk(req)->txhash, a separate one is needed for tcp_rsk(req)->ts_recent. BUG: KCSAN: data-race in tcp_make_synack / tcp_rtx_synack write to 0xffff8881362304bc of 4 bytes by task 32083 on cpu 1: tcp_rtx_synack+0x9d/0x2a0 net/ipv4/tcp_output.c:4213 inet_rtx_syn_ack+0x38/0x80 net/ipv4/inet_connection_sock.c:880 tcp_check_req+0x379/0xc70 net/ipv4/tcp_minisocks.c:665 tcp_v6_rcv+0x125b/0x1b20 net/ipv6/tcp_ipv6.c:1673 ip6_protocol_deliver_rcu+0x92f/0xf30 net/ipv6/ip6_input.c:437 ip6_input_finish net/ipv6/ip6_input.c:482 [inline] NF_HOOK include/linux/netfilter.h:303 [inline] ip6_input+0xbd/0x1b0 net/ipv6/ip6_input.c:491 dst_input include/net/dst.h:468 [inline] ip6_rcv_finish+0x1e2/0x2e0 net/ipv6/ip6_input.c:79 NF_HOOK include/linux/netfilter.h:303 [inline] ipv6_rcv+0x74/0x150 net/ipv6/ip6_input.c:309 __netif_receive_skb_one_core net/core/dev.c:5452 [inline] __netif_receive_skb+0x90/0x1b0 net/core/dev.c:5566 netif_receive_skb_internal net/core/dev.c:5652 [inline] netif_receive_skb+0x4a/0x310 net/core/dev.c:5711 tun_rx_batched+0x3bf/0x400 tun_get_user+0x1d24/0x22b0 drivers/net/tun.c:1997 tun_chr_write_iter+0x18e/0x240 drivers/net/tun.c:2043 call_write_iter include/linux/fs.h:1871 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x4ab/0x7d0 fs/read_write.c:584 ksys_write+0xeb/0x1a0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x42/0x50 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd read to 0xffff8881362304bc of 4 bytes by task 32078 on cpu 0: tcp_make_synack+0x367/0xb40 net/ipv4/tcp_output.c:3663 tcp_v6_send_synack+0x72/0x420 net/ipv6/tcp_ipv6.c:544 tcp_conn_request+0x11a8/0x1560 net/ipv4/tcp_input.c:7059 tcp_v6_conn_request+0x13f/0x180 net/ipv6/tcp_ipv6.c:1175 tcp_rcv_state_process+0x156/0x1de0 net/ipv4/tcp_input.c:6494 tcp_v6_do_rcv+0x98a/0xb70 net/ipv6/tcp_ipv6.c:1509 tcp_v6_rcv+0x17b8/0x1b20 net/ipv6/tcp_ipv6.c:1735 ip6_protocol_deliver_rcu+0x92f/0xf30 net/ipv6/ip6_input.c:437 ip6_input_finish net/ipv6/ip6_input.c:482 [inline] NF_HOOK include/linux/netfilter.h:303 [inline] ip6_input+0xbd/0x1b0 net/ipv6/ip6_input.c:491 dst_input include/net/dst.h:468 [inline] ip6_rcv_finish+0x1e2/0x2e0 net/ipv6/ip6_input.c:79 NF_HOOK include/linux/netfilter.h:303 [inline] ipv6_rcv+0x74/0x150 net/ipv6/ip6_input.c:309 __netif_receive_skb_one_core net/core/dev.c:5452 [inline] __netif_receive_skb+0x90/0x1b0 net/core/dev.c:5566 netif_receive_skb_internal net/core/dev.c:5652 [inline] netif_receive_skb+0x4a/0x310 net/core/dev.c:5711 tun_rx_batched+0x3bf/0x400 tun_get_user+0x1d24/0x22b0 drivers/net/tun.c:1997 tun_chr_write_iter+0x18e/0x240 drivers/net/tun.c:2043 call_write_iter include/linux/fs.h:1871 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x4ab/0x7d0 fs/read_write.c:584 ksys_write+0xeb/0x1a0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x42/0x50 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0x91d25731 -> 0xe79325cd Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 32078 Comm: syz-executor.4 Not tainted 6.5.0-rc1-syzkaller-00033-geb26cbb1a754 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023 Fixes: 58d607d3e52f ("tcp: provide skb->hash to synack packets") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://lore.kernel.org/r/20230717144445.653164-2-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-06-17tcp: enforce receive buffer memory limits by allowing the tcp window to shrinkmfreemon@cloudflare.com1-9/+51
Under certain circumstances, the tcp receive buffer memory limit set by autotuning (sk_rcvbuf) is increased due to incoming data packets as a result of the window not closing when it should be. This can result in the receive buffer growing all the way up to tcp_rmem[2], even for tcp sessions with a low BDP. To reproduce: Connect a TCP session with the receiver doing nothing and the sender sending small packets (an infinite loop of socket send() with 4 bytes of payload with a sleep of 1 ms in between each send()). This will cause the tcp receive buffer to grow all the way up to tcp_rmem[2]. As a result, a host can have individual tcp sessions with receive buffers of size tcp_rmem[2], and the host itself can reach tcp_mem limits, causing the host to go into tcp memory pressure mode. The fundamental issue is the relationship between the granularity of the window scaling factor and the number of byte ACKed back to the sender. This problem has previously been identified in RFC 7323, appendix F [1]. The Linux kernel currently adheres to never shrinking the window. In addition to the overallocation of memory mentioned above, the current behavior is functionally incorrect, because once tcp_rmem[2] is reached when no remediations remain (i.e. tcp collapse fails to free up any more memory and there are no packets to prune from the out-of-order queue), the receiver will drop in-window packets resulting in retransmissions and an eventual timeout of the tcp session. A receive buffer full condition should instead result in a zero window and an indefinite wait. In practice, this problem is largely hidden for most flows. It is not applicable to mice flows. Elephant flows can send data fast enough to "overrun" the sk_rcvbuf limit (in a single ACK), triggering a zero window. But this problem does show up for other types of flows. Examples are websockets and other type of flows that send small amounts of data spaced apart slightly in time. In these cases, we directly encounter the problem described in [1]. RFC 7323, section 2.4 [2], says there are instances when a retracted window can be offered, and that TCP implementations MUST ensure that they handle a shrinking window, as specified in RFC 1122, section 4.2.2.16 [3]. All prior RFCs on the topic of tcp window management have made clear that sender must accept a shrunk window from the receiver, including RFC 793 [4] and RFC 1323 [5]. This patch implements the functionality to shrink the tcp window when necessary to keep the right edge within the memory limit by autotuning (sk_rcvbuf). This new functionality is enabled with the new sysctl: net.ipv4.tcp_shrink_window Additional information can be found at: https://blog.cloudflare.com/unbounded-memory-usage-by-tcp-for-receive-buffers-and-how-we-fixed-it/ [1] https://www.rfc-editor.org/rfc/rfc7323#appendix-F [2] https://www.rfc-editor.org/rfc/rfc7323#section-2.4 [3] https://www.rfc-editor.org/rfc/rfc1122#page-91 [4] https://www.rfc-editor.org/rfc/rfc793 [5] https://www.rfc-editor.org/rfc/rfc1323 Signed-off-by: Mike Freemon <mfreemon@cloudflare.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-06-12tcp: remove size parameter from tcp_stream_alloc_skb()Eric Dumazet1-5/+5
Now all tcp_stream_alloc_skb() callers pass @size == 0, we can remove this parameter. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-06-12tcp: remove some dead codeEric Dumazet1-28/+12
Now all skbs in write queue do not contain any payload in skb->head, we can remove some dead code. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-06-12tcp: let tcp_send_syn_data() build headless packetsEric Dumazet1-12/+19
tcp_send_syn_data() is the last component in TCP transmit path to put payload in skb->head. Switch it to use page frags, so that we can remove dead code later. This allows to put more payload than previous implementation. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-06-09tcp: let tcp_mtu_probe() build headless packetsEric Dumazet1-2/+58
tcp_mtu_probe() is still copying payload from skbs in the write queue, using skb_copy_bits(), ignoring potential errors. Modern TCP stack wants to only deal with payload found in page frags, as this is a prereq for TCPDirect (host stack might not have access to the payload) Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20230607214113.1992947-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-03-18tcp: preserve const qualifier in tcp_sk()Eric Dumazet1-2/+7
We can change tcp_sk() to propagate its argument const qualifier, thanks to container_of_const(). We have two places where a const sock pointer has to be upgraded to a write one. We have been using const qualifier for lockless listeners to clearly identify points where writes could happen. Add tcp_sk_rw() helper to better document these. tcp_inbound_md5_hash(), __tcp_grow_window(), tcp_reset_check() and tcp_rack_reo_wnd() get an additional const qualififer for their @tp local variables. smc_check_reset_syn_req() also needs a similar change. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Simon Horman <simon.horman@corigine.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-03-18Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski1-1/+1
net/wireless/nl80211.c b27f07c50a73 ("wifi: nl80211: fix puncturing bitmap policy") cbbaf2bb829b ("wifi: nl80211: add a command to enable/disable HW timestamping") https://lore.kernel.org/all/20230314105421.3608efae@canb.auug.org.au tools/testing/selftests/net/Makefile 62199e3f1658 ("selftests: net: Add VXLAN MDB test") 13715acf8ab5 ("selftest: Add test for bind() conflicts.") Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-03-17tcp: annotate lockless access to sk->sk_errEric Dumazet1-1/+1
tcp_poll() reads sk->sk_err without socket lock held/owned. We should used READ_ONCE() here, and update writers to use WRITE_ONCE(). Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-03-10tcp: tcp_make_synack() can be called from process contextBreno Leitao1-1/+1
tcp_rtx_synack() now could be called in process context as explained in 0a375c822497 ("tcp: tcp_rtx_synack() can be called from process context"). tcp_rtx_synack() might call tcp_make_synack(), which will touch per-CPU variables with preemption enabled. This causes the following BUG: BUG: using __this_cpu_add() in preemptible [00000000] code: ThriftIO1/5464 caller is tcp_make_synack+0x841/0xac0 Call Trace: <TASK> dump_stack_lvl+0x10d/0x1a0 check_preemption_disabled+0x104/0x110 tcp_make_synack+0x841/0xac0 tcp_v6_send_synack+0x5c/0x450 tcp_rtx_synack+0xeb/0x1f0 inet_rtx_syn_ack+0x34/0x60 tcp_check_req+0x3af/0x9e0 tcp_rcv_state_process+0x59b/0x2030 tcp_v6_do_rcv+0x5f5/0x700 release_sock+0x3a/0xf0 tcp_sendmsg+0x33/0x40 ____sys_sendmsg+0x2f2/0x490 __sys_sendmsg+0x184/0x230 do_syscall_64+0x3d/0x90 Avoid calling __TCP_INC_STATS() with will touch per-cpu variables. Use TCP_INC_STATS() which is safe to be called from context switch. Fixes: 8336886f786f ("tcp: TCP Fast Open Server - support TFO listeners") Signed-off-by: Breno Leitao <leitao@debian.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20230308190745.780221-1-leitao@debian.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-12-02net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destructionDmitry Safonov1-2/+2
To do that, separate two scenarios: - where it's the first MD5 key on the system, which means that enabling of the static key may need to sleep; - copying of an existing key from a listening socket to the request socket upon receiving a signed TCP segment, where static key was already enabled (when the key was added to the listening socket). Now the life-time of the static branch for TCP-MD5 is until: - last tcp_md5sig_info is destroyed - last socket in time-wait state with MD5 key is closed. Which means that after all sockets with TCP-MD5 keys are gone, the system gets back the performance of disabled md5-key static branch. While at here, provide static_key_fast_inc() helper that does ref counter increment in atomic fashion (without grabbing cpus_read_lock() on CONFIG_JUMP_LABEL=y). This is needed to add a new user for a static_key when the caller controls the lifetime of another user. Signed-off-by: Dmitry Safonov <dima@arista.com> Acked-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-11-12tcp: tcp_wfree() refactoringEric Dumazet1-17/+14
Use try_cmpxchg() (instead of cmpxchg()) in a more readable way. oval = smp_load_acquire(&sk->sk_tsq_flags); do { ... } while (!try_cmpxchg(&sk->sk_tsq_flags, &oval, nval)); Reduce indentation level. Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20221110190239.3531280-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-11-12tcp: adopt try_cmpxchg() in tcp_release_cb()Eric Dumazet1-3/+3
try_cmpxchg() is slighly more efficient (at least on x86), and smp_load_acquire(&sk->sk_tsq_flags) could avoid a KCSAN report. Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20221110174829.3403442-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-30tcp: fix tcp_cwnd_validate() to not forget is_cwnd_limitedNeal Cardwell1-7/+12
This commit fixes a bug in the tracking of max_packets_out and is_cwnd_limited. This bug can cause the connection to fail to remember that is_cwnd_limited is true, causing the connection to fail to grow cwnd when it should, causing throughput to be lower than it should be. The following event sequence is an example that triggers the bug: (a) The connection is cwnd_limited, but packets_out is not at its peak due to TSO deferral deciding not to send another skb yet. In such cases the connection can advance max_packets_seq and set tp->is_cwnd_limited to true and max_packets_out to a small number. (b) Then later in the round trip the connection is pacing-limited (not cwnd-limited), and packets_out is larger. In such cases the connection would raise max_packets_out to a bigger number but (unexpectedly) flip tp->is_cwnd_limited from true to false. This commit fixes that bug. One straightforward fix would be to separately track (a) the next window after max_packets_out reaches a maximum, and (b) the next window after tp->is_cwnd_limited is set to true. But this would require consuming an extra u32 sequence number. Instead, to save space we track only the most important information. Specifically, we track the strongest available signal of the degree to which the cwnd is fully utilized: (1) If the connection is cwnd-limited then we remember that fact for the current window. (2) If the connection not cwnd-limited then we track the maximum number of outstanding packets in the current window. In particular, note that the new logic cannot trigger the buggy (a)/(b) sequence above because with the new logic a condition where tp->packets_out > tp->max_packets_out can only trigger an update of tp->is_cwnd_limited if tp->is_cwnd_limited is false. This first showed up in a testing of a BBRv2 dev branch, but this buggy behavior highlighted a general issue with the tcp_cwnd_validate() logic that can cause cwnd to fail to increase at the proper rate for any TCP congestion control, including Reno or CUBIC. Fixes: ca8a22634381 ("tcp: make cwnd-limited checks measurement-based, and gentler") Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Kevin(Yudong) Yang <yyd@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-08-24net: Fix data-races around sysctl_[rw]mem_(max|default).Kuniyuki Iwashima1-1/+1
While reading sysctl_[rw]mem_(max|default), they can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-29Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski1-15/+12
No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-25net: Fix data-races around sysctl_[rw]mem(_offset)?.Kuniyuki Iwashima1-1/+1
While reading these sysctl variables, they can be changed concurrently. Thus, we need to add READ_ONCE() to their readers. - .sysctl_rmem - .sysctl_rwmem - .sysctl_rmem_offset - .sysctl_wmem_offset - sysctl_tcp_rmem[1, 2] - sysctl_tcp_wmem[1, 2] - sysctl_decnet_rmem[1] - sysctl_decnet_wmem[1] - sysctl_tipc_rmem[1] Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-23Revert "tcp: change pingpong threshold to 3"Wei Wang1-9/+6
This reverts commit 4a41f453bedfd5e9cd040bad509d9da49feb3e2c. This to-be-reverted commit was meant to apply a stricter rule for the stack to enter pingpong mode. However, the condition used to check for interactive session "before(tp->lsndtime, icsk->icsk_ack.lrcvtime)" is jiffy based and might be too coarse, which delays the stack entering pingpong mode. We revert this patch so that we no longer use the above condition to determine interactive session, and also reduce pingpong threshold to 1. Fixes: 4a41f453bedf ("tcp: change pingpong threshold to 3") Reported-by: LemmyHuang <hlm3280@163.com> Suggested-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20220721204404.388396-1-weiwan@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-22tcp: Fix a data-race around sysctl_tcp_tso_rtt_log.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_tso_rtt_log, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 65466904b015 ("tcp: adjust TSO packet sizes based on min_rtt") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-22tcp: Fix a data-race around sysctl_tcp_min_tso_segs.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_min_tso_segs, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 95bd09eb2750 ("tcp: TSO packets automatic sizing") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-22tcp: Fix a data-race around sysctl_tcp_limit_output_bytes.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_limit_output_bytes, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 46d3ceabd8d9 ("tcp: TCP Small Queues") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-22tcp: Fix data-races around sysctl_tcp_workaround_signed_windows.Kuniyuki Iwashima1-2/+2
While reading sysctl_tcp_workaround_signed_windows, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 15d99e02baba ("[TCP]: sysctl to allow TCP window > 32767 sans wscale") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-21Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski1-14/+15
No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-20tcp: Fix a data-race around sysctl_tcp_retrans_collapse.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_retrans_collapse, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-20tcp: Fix data-races around sysctl_tcp_slow_start_after_idle.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_slow_start_after_idle, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 35089bb203f4 ("[TCP]: Add tcp_slow_start_after_idle sysctl.") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-20tcp: Fix a data-race around sysctl_tcp_early_retrans.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_early_retrans, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: eed530b6c676 ("tcp: early retransmit") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-20tcp: Fix data-races around sysctl knobs related to SYN option.Kuniyuki Iwashima1-5/+5
While reading these knobs, they can be changed concurrently. Thus, we need to add READ_ONCE() to their readers. - tcp_sack - tcp_window_scaling - tcp_timestamps Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-18tcp: Fix data-races around some timeout sysctl knobs.Kuniyuki Iwashima1-1/+1
While reading these sysctl knobs, they can be changed concurrently. Thus, we need to add READ_ONCE() to their readers. - tcp_retries1 - tcp_retries2 - tcp_orphan_retries - tcp_fin_timeout Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-15tcp: Fix a data-race around sysctl_tcp_probe_interval.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_probe_interval, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 05cbc0db03e8 ("ipv4: Create probe timer for tcp PMTU as per RFC4821") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-15tcp: Fix a data-race around sysctl_tcp_probe_threshold.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_probe_threshold, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 6b58e0a5f32d ("ipv4: Use binary search to choose tcp PMTU probe_size") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-15tcp: Fix data-races around sysctl_tcp_min_snd_mss.Kuniyuki Iwashima1-1/+2
While reading sysctl_tcp_min_snd_mss, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 5f3e2bf008c2 ("tcp: add tcp_min_snd_mss sysctl") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-15tcp: Fix data-races around sysctl_tcp_base_mss.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_base_mss, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 5d424d5a674f ("[TCP]: MTU probing") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-15tcp: Fix data-races around sysctl_tcp_mtu_probing.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_mtu_probing, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 5d424d5a674f ("[TCP]: MTU probing") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-15Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski1-2/+2
include/net/sock.h 310731e2f161 ("net: Fix data-races around sysctl_mem.") e70f3c701276 ("Revert "net: set SK_MEM_QUANTUM to 4096"") https://lore.kernel.org/all/20220711120211.7c8b7cba@canb.auug.org.au/ net/ipv4/fib_semantics.c 747c14307214 ("ip: fix dflt addr selection for connected nexthop") d62607c3fe45 ("net: rename reference+tracking helpers") net/tls/tls.h include/net/tls.h 3d8c51b25a23 ("net/tls: Check for errors in tls_device_init") 587903142308 ("tls: create an internal header") Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-13tcp: Fix a data-race around sysctl_tcp_ecn_fallback.Kuniyuki Iwashima1-1/+1
While reading sysctl_tcp_ecn_fallback, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 492135557dc0 ("tcp: add rfc3168, section 6.1.1.1. fallback") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
generated by cgit v1.2.3 (git 2.39.0) at 2024-10-25 14:33:28 +0300