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2019-04-16tcp: tcp_grow_window() needs to respect tcp_space()Eric Dumazet1-5/+5
For some reason, tcp_grow_window() correctly tests if enough room is present before attempting to increase tp->rcv_ssthresh, but does not prevent it to grow past tcp_space() This is causing hard to debug issues, like failing the (__tcp_select_window(sk) >= tp->rcv_wnd) test in __tcp_ack_snd_check(), causing ACK delays and possibly slow flows. Depending on tcp_rmem[2], MTU, skb->len/skb->truesize ratio, we can see the problem happening on "netperf -t TCP_RR -- -r 2000,2000" after about 60 round trips, when the active side no longer sends immediate acks. This bug predates git history. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Wei Wang <weiwan@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-08tcp: handle inet_csk_reqsk_queue_add() failuresGuillaume Nault1-1/+7
Commit 7716682cc58e ("tcp/dccp: fix another race at listener dismantle") let inet_csk_reqsk_queue_add() fail, and adjusted {tcp,dccp}_check_req() accordingly. However, TFO and syncookies weren't modified, thus leaking allocated resources on error. Contrary to tcp_check_req(), in both syncookies and TFO cases, we need to drop the request socket. Also, since the child socket is created with inet_csk_clone_lock(), we have to unlock it and drop an extra reference (->sk_refcount is initially set to 2 and inet_csk_reqsk_queue_add() drops only one ref). For TFO, we also need to revert the work done by tcp_try_fastopen() (with reqsk_fastopen_remove()). Fixes: 7716682cc58e ("tcp/dccp: fix another race at listener dismantle") Signed-off-by: Guillaume Nault <gnault@redhat.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2019-02-25tcp: clean up SOCK_DEBUG()Yafang Shao1-18/+1
Per discussion with Daniel[1] and Eric[2], these SOCK_DEBUG() calles in TCP are not needed now. We'd better clean up it. [1] https://patchwork.ozlabs.org/patch/1035573/ [2] https://patchwork.ozlabs.org/patch/1040533/ Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2019-02-25tcp: remove unused parameter of tcp_sacktag_bsearch()Taehee Yoo1-10/+6
parameter state in the tcp_sacktag_bsearch() is not used. So, it can be removed. Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2019-01-27tcp: Refactor pingpong codeWei Wang1-4/+4
Instead of using pingpong as a single bit information, we refactor the code to treat it as a counter. When interactive session is detected, we set pingpong count to TCP_PINGPONG_THRESH. And when pingpong count is >= TCP_PINGPONG_THRESH, we consider the session in pingpong mode. This patch is a pure refactor and sets foundation for the next patch. This patch itself does not change any pingpong logic. Signed-off-by: Wei Wang <weiwan@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>
2018-11-30tcp: take care of compressed acks in tcp_add_reno_sack()Eric Dumazet1-25/+33
Neal pointed out that non sack flows might suffer from ACK compression added in the following patch ("tcp: implement coalescing on backlog queue") Instead of tweaking tcp_add_backlog() we can take into account how many ACK were coalesced, this information will be available in skb_shinfo(skb)->gso_segs Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-28Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-6/+10
Trivial conflict in net/core/filter.c, a locally computed 'sdif' is now an argument to the function. Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-27tcp: remove hdrlen argument from tcp_queue_rcv()Eric Dumazet1-7/+6
Only one caller needs to pull TCP headers, so lets move __skb_pull() to the caller side. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-24tcp: address problems caused by EDT misshapsEric Dumazet1-6/+10
When a qdisc setup including pacing FQ is dismantled and recreated, some TCP packets are sent earlier than instructed by TCP stack. TCP can be fooled when ACK comes back, because the following operation can return a negative value. tcp_time_stamp(tp) - tp->rx_opt.rcv_tsecr; Some paths in TCP stack were not dealing properly with this, this patch addresses four of them. Fixes: ab408b6dc744 ("tcp: switch tcp and sch_fq to new earliest departure time model") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-24Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-2/+13
2018-11-21tcp: defer SACK compression after DupThreshEric Dumazet1-2/+12
Jean-Louis reported a TCP regression and bisected to recent SACK compression. After a loss episode (receiver not able to keep up and dropping packets because its backlog is full), linux TCP stack is sending a single SACK (DUPACK). Sender waits a full RTO timer before recovering losses. While RFC 6675 says in section 5, "Algorithm Details", (2) If DupAcks < DupThresh but IsLost (HighACK + 1) returns true -- indicating at least three segments have arrived above the current cumulative acknowledgment point, which is taken to indicate loss -- go to step (4). ... (4) Invoke fast retransmit and enter loss recovery as follows: there are old TCP stacks not implementing this strategy, and still counting the dupacks before starting fast retransmit. While these stacks probably perform poorly when receivers implement LRO/GRO, we should be a little more gentle to them. This patch makes sure we do not enable SACK compression unless 3 dupacks have been sent since last rcv_nxt update. Ideally we should even rearm the timer to send one or two more DUPACK if no more packets are coming, but that will be work aiming for linux-4.21. Many thanks to Jean-Louis for bisecting the issue, providing packet captures and testing this patch. Fixes: 5d9f4262b7ea ("tcp: add SACK compression") Reported-by: Jean-Louis Dupond <jean-louis@dupond.be> Tested-by: Jean-Louis Dupond <jean-louis@dupond.be> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-20tcp: Fix SOF_TIMESTAMPING_RX_HARDWARE to use the latest timestamp during TCP ↵Stephen Mallon1-0/+1
coalescing During tcp coalescing ensure that the skb hardware timestamp refers to the highest sequence number data. Previously only the software timestamp was updated during coalescing. Signed-off-by: Stephen Mallon <stephen.mallon@sydney.edu.au> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-11tcp: minor optimization in tcp ack fast path processingYafang Shao1-3/+4
Bitwise operation is a little faster. So I replace after() with using the flag FLAG_SND_UNA_ADVANCED as it is already set before. In addtion, there's another similar improvement in tcp_cwnd_reduction(). Cc: Joe Perches <joe@perches.com> Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-10-23tcp: add tcp_reset_xmit_timer() helperEric Dumazet1-4/+4
With EDT model, SRTT no longer is inflated by pacing delays. This means that RTO and some other xmit timers might be setup incorrectly. This is particularly visible with either : - Very small enforced pacing rates (SO_MAX_PACING_RATE) - Reduced rto (from the default 200 ms) This can lead to TCP flows aborts in the worst case, or spurious retransmits in other cases. For example, this session gets far more throughput than the requested 80kbit : $ netperf -H 127.0.0.2 -l 100 -- -q 10000 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 127.0.0.2 () port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 540000 262144 262144 104.00 2.66 With the fix : $ netperf -H 127.0.0.2 -l 100 -- -q 10000 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 127.0.0.2 () port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 540000 262144 262144 104.00 0.12 EDT allows for better control of rtx timers, since TCP has a better idea of the earliest departure time of each skb in the rtx queue. We only have to eventually add to the timer the difference of the EDT time with current time. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-10-03Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-1/+3
Minor conflict in net/core/rtnetlink.c, David Ahern's bug fix in 'net' overlapped the renaming of a netlink attribute in net-next. Signed-off-by: David S. Miller <davem@davemloft.net>
2018-10-01tcp: start receiver buffer autotuning soonerYuchung Cheng1-1/+1
Previously receiver buffer auto-tuning starts after receiving one advertised window amount of data. After the initial receiver buffer was raised by patch a337531b942b ("tcp: up initial rmem to 128KB and SYN rwin to around 64KB"), the reciver buffer may take too long to start raising. To address this issue, this patch lowers the initial bytes expected to receive roughly the expected sender's initial window. Fixes: a337531b942b ("tcp: up initial rmem to 128KB and SYN rwin to around 64KB") Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-10-01tcp/dccp: fix lockdep issue when SYN is backloggedEric Dumazet1-1/+3
In normal SYN processing, packets are handled without listener lock and in RCU protected ingress path. But syzkaller is known to be able to trick us and SYN packets might be processed in process context, after being queued into socket backlog. In commit 06f877d613be ("tcp/dccp: fix other lockdep splats accessing ireq_opt") I made a very stupid fix, that happened to work mostly because of the regular path being RCU protected. Really the thing protecting ireq->ireq_opt is RCU read lock, and the pseudo request refcnt is not relevant. This patch extends what I did in commit 449809a66c1d ("tcp/dccp: block BH for SYN processing") by adding an extra rcu_read_{lock|unlock} pair in the paths that might be taken when processing SYN from socket backlog (thus possibly in process context) Fixes: 06f877d613be ("tcp/dccp: fix other lockdep splats accessing ireq_opt") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-09-29tcp: up initial rmem to 128KB and SYN rwin to around 64KBYuchung Cheng1-23/+2
Previously TCP initial receive buffer is ~87KB by default and the initial receive window is ~29KB (20 MSS). This patch changes the two numbers to 128KB and ~64KB (rounding down to the multiples of MSS) respectively. The patch also simplifies the calculations s.t. the two numbers are directly controlled by sysctl tcp_rmem[1]: 1) Initial receiver buffer budget (sk_rcvbuf): while this should be configured via sysctl tcp_rmem[1], previously tcp_fixup_rcvbuf() always override and set a larger size when a new connection establishes. 2) Initial receive window in SYN: previously it is set to 20 packets if MSS <= 1460. The number 20 was based on the initial congestion window of 10: the receiver needs twice amount to avoid being limited by the receive window upon out-of-order delivery in the first window burst. But since this only applies if the receiving MSS <= 1460, connection using large MTU (e.g. to utilize receiver zero-copy) may be limited by the receive window. With this patch TCP memory configuration is more straight-forward and more properly sized to modern high-speed networks by default. Several popular stacks have been announcing 64KB rwin in SYNs as well. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-09-21tcp: introduce tcp_skb_timestamp_us() helperEric Dumazet1-5/+6
There are few places where TCP reads skb->skb_mstamp expecting a value in usec unit. skb->tstamp (aka skb->skb_mstamp) will soon store CLOCK_TAI nsec value. Add tcp_skb_timestamp_us() to provide proper conversion when needed. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-09-12Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-2/+2
2018-09-11tcp: rate limit synflood warnings furtherWillem de Bruijn1-2/+2
Convert pr_info to net_info_ratelimited to limit the total number of synflood warnings. Commit 946cedccbd73 ("tcp: Change possible SYN flooding messages") rate limits synflood warnings to one per listener. Workloads that open many listener sockets can still see a high rate of log messages. Syzkaller is one frequent example. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-31tcp: change IPv6 flow-label upon receiving spurious retransmissionYuchung Cheng1-0/+13
Currently a Linux IPv6 TCP sender will change the flow label upon timeouts to potentially steer away from a data path that has gone bad. However this does not help if the problem is on the ACK path and the data path is healthy. In this case the receiver is likely to receive repeated spurious retransmission because the sender couldn't get the ACKs in time and has recurring timeouts. This patch adds another feature to mitigate this problem. It leverages the DSACK states in the receiver to change the flow label of the ACKs to speculatively re-route the ACK packets. In order to allow triggering on the second consecutive spurious RTO, the receiver changes the flow label upon sending a second consecutive DSACK for a sequence number below RCV.NXT. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-11tcp: avoid resetting ACK timer upon receiving packet with ECN CWR flagYuchung Cheng1-4/+4
Previously commit 9aee40006190 ("tcp: ack immediately when a cwr packet arrives") calls tcp_enter_quickack_mode to force sending two immediate ACKs upon receiving a packet w/ CWR flag. The side effect is it'll also reset the delayed ACK timer and interactive session tracking. This patch removes that side effect by using the new ACK_NOW flag to force an immmediate ACK. Packetdrill to demonstrate: 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 setsockopt(3, SOL_TCP, TCP_CONGESTION, "dctcp", 5) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 +0 < [ect0] SEW 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7> +0 > SE. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8> +.1 < [ect0] . 1:1(0) ack 1 win 257 +0 accept(3, ..., ...) = 4 +0 < [ect0] . 1:1001(1000) ack 1 win 257 +0 > [ect01] . 1:1(0) ack 1001 +0 write(4, ..., 1) = 1 +0 > [ect01] P. 1:2(1) ack 1001 +0 < [ect0] . 1001:2001(1000) ack 2 win 257 +0 write(4, ..., 1) = 1 +0 > [ect01] P. 2:3(1) ack 2001 +0 < [ect0] . 2001:3001(1000) ack 3 win 257 +0 < [ect0] . 3001:4001(1000) ack 3 win 257 // Ack delayed ... +.01 < [ce] P. 4001:4501(500) ack 3 win 257 +0 > [ect01] . 3:3(0) ack 4001 +0 > [ect01] E. 3:3(0) ack 4501 +.001 read(4, ..., 4500) = 4500 +0 write(4, ..., 1) = 1 +0 > [ect01] PE. 3:4(1) ack 4501 win 100 +.01 < [ect0] W. 4501:5501(1000) ack 4 win 257 // No delayed ACK on CWR flag +0 > [ect01] . 4:4(0) ack 5501 +.31 < [ect0] . 5501:6501(1000) ack 4 win 257 +0 > [ect01] . 4:4(0) ack 6501 Fixes: 9aee40006190 ("tcp: ack immediately when a cwr packet arrives") Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-11tcp: always ACK immediately on hole repairsYuchung Cheng1-2/+2
RFC 5681 sec 4.2: To provide feedback to senders recovering from losses, the receiver SHOULD send an immediate ACK when it receives a data segment that fills in all or part of a gap in the sequence space. When a gap is partially filled, __tcp_ack_snd_check already checks the out-of-order queue and correctly send an immediate ACK. However when a gap is fully filled, the previous implementation only resets pingpong mode which does not guarantee an immediate ACK because the quick ACK counter may be zero. This patch addresses this issue by marking the one-time immediate ACK flag instead. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-11tcp: mandate a one-time immediate ACKYuchung Cheng1-1/+3
Add a new flag to indicate a one-time immediate ACK. This flag is occasionaly set under specific TCP protocol states in addition to the more common quickack mechanism for interactive application. In several cases in the TCP code we want to force an immediate ACK but do not want to call tcp_enter_quickack_mode() because we do not want to forget the icsk_ack.pingpong or icsk_ack.ato state. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-02Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-1/+8
The BTF conflicts were simple overlapping changes. The virtio_net conflict was an overlap of a fix of statistics counter, happening alongisde a move over to a bonafide statistics structure rather than counting value on the stack. Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-01tcp: add stat of data packet reordering eventsWei Wang1-1/+2
Introduce a new TCP stats to record the number of reordering events seen and expose it in both tcp_info (TCP_INFO) and opt_stats (SOF_TIMESTAMPING_OPT_STATS). Application can use this stats to track the frequency of the reordering events in addition to the existing reordering stats which tracks the magnitude of the latest reordering event. Note: this new stats tracks reordering events triggered by ACKs, which could often be fewer than the actual number of packets being delivered out-of-order. Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-01tcp: add dsack blocks received statsWei Wang1-0/+1
Introduce a new TCP stat to record the number of DSACK blocks received (RFC4989 tcpEStatsStackDSACKDups) and expose it in both tcp_info (TCP_INFO) and opt_stats (SOF_TIMESTAMPING_OPT_STATS). Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-25tcp: ack immediately when a cwr packet arrivesLawrence Brakmo1-1/+8
We observed high 99 and 99.9% latencies when doing RPCs with DCTCP. The problem is triggered when the last packet of a request arrives CE marked. The reply will carry the ECE mark causing TCP to shrink its cwnd to 1 (because there are no packets in flight). When the 1st packet of the next request arrives, the ACK was sometimes delayed even though it is CWR marked, adding up to 40ms to the RPC latency. This patch insures that CWR marked data packets arriving will be acked immediately. Packetdrill script to reproduce the problem: 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 0.000 setsockopt(3, SOL_TCP, TCP_CONGESTION, "dctcp", 5) = 0 0.000 bind(3, ..., ...) = 0 0.000 listen(3, 1) = 0 0.100 < [ect0] SEW 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7> 0.100 > SE. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8> 0.110 < [ect0] . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 0.200 < [ect0] . 1:1001(1000) ack 1 win 257 0.200 > [ect01] . 1:1(0) ack 1001 0.200 write(4, ..., 1) = 1 0.200 > [ect01] P. 1:2(1) ack 1001 0.200 < [ect0] . 1001:2001(1000) ack 2 win 257 0.200 write(4, ..., 1) = 1 0.200 > [ect01] P. 2:3(1) ack 2001 0.200 < [ect0] . 2001:3001(1000) ack 3 win 257 0.200 < [ect0] . 3001:4001(1000) ack 3 win 257 0.200 > [ect01] . 3:3(0) ack 4001 0.210 < [ce] P. 4001:4501(500) ack 3 win 257 +0.001 read(4, ..., 4500) = 4500 +0 write(4, ..., 1) = 1 +0 > [ect01] PE. 3:4(1) ack 4501 +0.010 < [ect0] W. 4501:5501(1000) ack 4 win 257 // Previously the ACK sequence below would be 4501, causing a long RTO +0.040~+0.045 > [ect01] . 4:4(0) ack 5501 // delayed ack +0.311 < [ect0] . 5501:6501(1000) ack 4 win 257 // More data +0 > [ect01] . 4:4(0) ack 6501 // now acks everything +0.500 < F. 9501:9501(0) ack 4 win 257 Modified based on comments by Neal Cardwell <ncardwell@google.com> Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-24Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-13/+52
2018-07-23tcp: add tcp_ooo_try_coalesce() helperEric Dumazet1-4/+21
In case skb in out_or_order_queue is the result of multiple skbs coalescing, we would like to get a proper gso_segs counter tracking, so that future tcp_drop() can report an accurate number. I chose to not implement this tracking for skbs in receive queue, since they are not dropped, unless socket is disconnected. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-23tcp: call tcp_drop() from tcp_data_queue_ofo()Eric Dumazet1-2/+2
In order to be able to give better diagnostics and detect malicious traffic, we need to have better sk->sk_drops tracking. Fixes: 9f5afeae5152 ("tcp: use an RB tree for ooo receive queue") Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-23tcp: detect malicious patterns in tcp_collapse_ofo_queue()Eric Dumazet1-2/+13
In case an attacker feeds tiny packets completely out of order, tcp_collapse_ofo_queue() might scan the whole rb-tree, performing expensive copies, but not changing socket memory usage at all. 1) Do not attempt to collapse tiny skbs. 2) Add logic to exit early when too many tiny skbs are detected. We prefer not doing aggressive collapsing (which copies packets) for pathological flows, and revert to tcp_prune_ofo_queue() which will be less expensive. In the future, we might add the possibility of terminating flows that are proven to be malicious. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-23tcp: avoid collapses in tcp_prune_queue() if possibleEric Dumazet1-0/+3
Right after a TCP flow is created, receiving tiny out of order packets allways hit the condition : if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf) tcp_clamp_window(sk); tcp_clamp_window() increases sk_rcvbuf to match sk_rmem_alloc (guarded by tcp_rmem[2]) Calling tcp_collapse_ofo_queue() in this case is not useful, and offers a O(N^2) surface attack to malicious peers. Better not attempt anything before full queue capacity is reached, forcing attacker to spend lots of resource and allow us to more easily detect the abuse. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-23tcp: free batches of packets in tcp_prune_ofo_queue()Eric Dumazet1-4/+11
Juha-Matti Tilli reported that malicious peers could inject tiny packets in out_of_order_queue, forcing very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet. out_of_order_queue rb-tree can contain thousands of nodes, iterating over all of them is not nice. Before linux-4.9, we would have pruned all packets in ofo_queue in one go, every XXXX packets. XXXX depends on sk_rcvbuf and skbs truesize, but is about 7000 packets with tcp_rmem[2] default of 6 MB. Since we plan to increase tcp_rmem[2] in the future to cope with modern BDP, can not revert to the old behavior, without great pain. Strategy taken in this patch is to purge ~12.5 % of the queue capacity. Fixes: 36a6503fedda ("tcp: refine tcp_prune_ofo_queue() to not drop all packets") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Juha-Matti Tilli <juha-matti.tilli@iki.fi> Acked-by: Yuchung Cheng <ycheng@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-20tcp: do not delay ACK in DCTCP upon CE status changeYuchung Cheng1-1/+2
Per DCTCP RFC8257 (Section 3.2) the ACK reflecting the CE status change has to be sent immediately so the sender can respond quickly: """ When receiving packets, the CE codepoint MUST be processed as follows: 1. If the CE codepoint is set and DCTCP.CE is false, set DCTCP.CE to true and send an immediate ACK. 2. If the CE codepoint is not set and DCTCP.CE is true, set DCTCP.CE to false and send an immediate ACK. """ Previously DCTCP implementation may continue to delay the ACK. This patch fixes that to implement the RFC by forcing an immediate ACK. Tested with this packetdrill script provided by Larry Brakmo 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 0.000 setsockopt(3, SOL_TCP, TCP_CONGESTION, "dctcp", 5) = 0 0.000 bind(3, ..., ...) = 0 0.000 listen(3, 1) = 0 0.100 < [ect0] SEW 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7> 0.100 > SE. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8> 0.110 < [ect0] . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_SOCKET, SO_DEBUG, [1], 4) = 0 0.200 < [ect0] . 1:1001(1000) ack 1 win 257 0.200 > [ect01] . 1:1(0) ack 1001 0.200 write(4, ..., 1) = 1 0.200 > [ect01] P. 1:2(1) ack 1001 0.200 < [ect0] . 1001:2001(1000) ack 2 win 257 +0.005 < [ce] . 2001:3001(1000) ack 2 win 257 +0.000 > [ect01] . 2:2(0) ack 2001 // Previously the ACK below would be delayed by 40ms +0.000 > [ect01] E. 2:2(0) ack 3001 +0.500 < F. 9501:9501(0) ack 4 win 257 Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-16tcp: Don't coalesce decrypted and encrypted SKBsBoris Pismenny1-0/+12
Prevent coalescing of decrypted and encrypted SKBs in GRO and TCP layer. Signed-off-by: Boris Pismenny <borisp@mellanox.com> Signed-off-by: Ilya Lesokhin <ilyal@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-14tcp: remove redundant rcv_nxt updateYafang Shao1-1/+0
tcp_rcv_nxt_update() is already executed in tcp_data_queue(). This line is redundant. See bellow, tcp_queue_rcv tcp_rcv_nxt_update(tcp_sk(sk), TCP_SKB_CB(skb)->end_seq); tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq); <<<< redundant Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-12tcp: use monotonic timestamps for PAWSArnd Bergmann1-1/+1
Using get_seconds() for timestamps is deprecated since it can lead to overflows on 32-bit systems. While the interface generally doesn't overflow until year 2106, the specific implementation of the TCP PAWS algorithm breaks in 2038 when the intermediate signed 32-bit timestamps overflow. A related problem is that the local timestamps in CLOCK_REALTIME form lead to unexpected behavior when settimeofday is called to set the system clock backwards or forwards by more than 24 days. While the first problem could be solved by using an overflow-safe method of comparing the timestamps, a nicer solution is to use a monotonic clocksource with ktime_get_seconds() that simply doesn't overflow (at least not until 136 years after boot) and that doesn't change during settimeofday(). To make 32-bit and 64-bit architectures behave the same way here, and also save a few bytes in the tcp_options_received structure, I'm changing the type to a 32-bit integer, which is now safe on all architectures. Finally, the ts_recent_stamp field also (confusingly) gets used to store a jiffies value in tcp_synq_overflow()/tcp_synq_no_recent_overflow(). This is currently safe, but changing the type to 32-bit requires some small changes there to keep it working. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-03Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-2/+11
Simple overlapping changes in stmmac driver. Adjust skb_gro_flush_final_remcsum function signature to make GRO list changes in net-next, as per Stephen Rothwell's example merge resolution. Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-02net: Record receive queue number for a connectionAmritha Nambiar1-0/+3
This patch adds a new field to sock_common 'skc_rx_queue_mapping' which holds the receive queue number for the connection. The Rx queue is marked in tcp_finish_connect() to allow a client app to do SO_INCOMING_NAPI_ID after a connect() call to get the right queue association for a socket. Rx queue is also marked in tcp_conn_request() to allow syn-ack to go on the right tx-queue associated with the queue on which syn is received. Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com> Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-01tcp: prevent bogus FRTO undos with non-SACK flowsIlpo Järvinen1-0/+9
If SACK is not enabled and the first cumulative ACK after the RTO retransmission covers more than the retransmitted skb, a spurious FRTO undo will trigger (assuming FRTO is enabled for that RTO). The reason is that any non-retransmitted segment acknowledged will set FLAG_ORIG_SACK_ACKED in tcp_clean_rtx_queue even if there is no indication that it would have been delivered for real (the scoreboard is not kept with TCPCB_SACKED_ACKED bits in the non-SACK case so the check for that bit won't help like it does with SACK). Having FLAG_ORIG_SACK_ACKED set results in the spurious FRTO undo in tcp_process_loss. We need to use more strict condition for non-SACK case and check that none of the cumulatively ACKed segments were retransmitted to prove that progress is due to original transmissions. Only then keep FLAG_ORIG_SACK_ACKED set, allowing FRTO undo to proceed in non-SACK case. (FLAG_ORIG_SACK_ACKED is planned to be renamed to FLAG_ORIG_PROGRESS to better indicate its purpose but to keep this change minimal, it will be done in another patch). Besides burstiness and congestion control violations, this problem can result in RTO loop: When the loss recovery is prematurely undoed, only new data will be transmitted (if available) and the next retransmission can occur only after a new RTO which in case of multiple losses (that are not for consecutive packets) requires one RTO per loss to recover. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Tested-by: Neal Cardwell <ncardwell@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-30tcp: add new SNMP counter for drops when try to queue in rcv queueYafang Shao1-2/+6
When sk_rmem_alloc is larger than the receive buffer and we can't schedule more memory for it, the skb will be dropped. In above situation, if this skb is put into the ofo queue, LINUX_MIB_TCPOFODROP is incremented to track it. While if this skb is put into the receive queue, there's no record. So a new SNMP counter is introduced to track this behavior. LINUX_MIB_TCPRCVQDROP: Number of packets meant to be queued in rcv queue but dropped because socket rcvbuf limit hit. Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-28tcp: add one more quick ack after after ECN eventsEric Dumazet1-2/+2
Larry Brakmo proposal ( https://patchwork.ozlabs.org/patch/935233/ tcp: force cwnd at least 2 in tcp_cwnd_reduction) made us rethink about our recent patch removing ~16 quick acks after ECN events. tcp_enter_quickack_mode(sk, 1) makes sure one immediate ack is sent, but in the case the sender cwnd was lowered to 1, we do not want to have a delayed ack for the next packet we will receive. Fixes: 522040ea5fdd ("tcp: do not aggressively quick ack after ECN events") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Neal Cardwell <ncardwell@google.com> Cc: Lawrence Brakmo <brakmo@fb.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-26tcp: add SNMP counter for zero-window dropsYafang Shao1-2/+6
It will be helpful if we could display the drops due to zero window or no enough window space. So a new SNMP MIB entry is added to track this behavior. This entry is named LINUX_MIB_TCPZEROWINDOWDROP and published in /proc/net/netstat in TcpExt line as TCPZeroWindowDrop. Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-22tcp: ignore rcv_rtt sample with old ts ecr valueWei Wang1-3/+11
When receiving multiple packets with the same ts ecr value, only try to compute rcv_rtt sample with the earliest received packet. This is because the rcv_rtt calculated by later received packets could possibly include long idle time or other types of delay. For example: (1) server sends last packet of reply with TS val V1 (2) client ACKs last packet of reply with TS ecr V1 (3) long idle time passes (4) client sends next request data packet with TS ecr V1 (again!) At this time, the rcv_rtt computed on server with TS ecr V1 will be inflated with the idle time and should get ignored. Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-05tcp: refactor tcp_ecn_check_ce to remove sk type castYousuk Seung1-12/+14
Refactor tcp_ecn_check_ce and __tcp_ecn_check_ce to accept struct sock* instead of tcp_sock* to clean up type casts. This is a pure refactor patch. Signed-off-by: Yousuk Seung <ysseung@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-31tcp: minor optimization around tcp_hdr() usage in receive pathYafang Shao1-3/+3
This is additional to the commit ea1627c20c34 ("tcp: minor optimizations around tcp_hdr() usage"). At this point, skb->data is same with tcp_hdr() as tcp header has not been pulled yet. So use the less expensive one to get the tcp header. Remove the third parameter of tcp_rcv_established() and put it into the function body. Furthermore, the local variables are listed as a reverse christmas tree :) Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-22tcp: do not aggressively quick ack after ECN eventsEric Dumazet1-2/+2
ECN signals currently forces TCP to enter quickack mode for up to 16 (TCP_MAX_QUICKACKS) following incoming packets. We believe this is not needed, and only sending one immediate ack for the current packet should be enough. This should reduce the extra load noticed in DCTCP environments, after congestion events. This is part 2 of our effort to reduce pure ACK packets. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-22tcp: add max_quickacks param to tcp_incr_quickack and tcp_enter_quickack_modeEric Dumazet1-11/+13
We want to add finer control of the number of ACK packets sent after ECN events. This patch is not changing current behavior, it only enables following change. 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>
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