linux.git/net/ipv4/tcp_input.c, branch v5.12

tcp: tcp_data_ready() must look at SOCK_DONE

2021-02-15T21:20:36+00:00

My prior cleanup missed that tcp_data_ready() has to look at SOCK_DONE.
Otherwise, an application using SO_RCVLOWAT will not get EPOLLIN event
if a FIN is received in the middle of expected payload.

The reason SOCK_DONE is not examined in tcp_epollin_ready()
is that tcp_poll() catches the FIN because tcp_fin()
is also setting RCV_SHUTDOWN into sk->sk_shutdown

Fixes: 05dc72aba364 ("tcp: factorize logic into tcp_epollin_ready()")
Signed-off-by: Eric Dumazet 
Reported-by: Wei Wang 
Cc: Arjun Roy 
Reviewed-by: Wei Wang 
Signed-off-by: David S. Miller

tcp: factorize logic into tcp_epollin_ready()

2021-02-13T01:28:26+00:00

Both tcp_data_ready() and tcp_stream_is_readable() share the same logic.

Add tcp_epollin_ready() helper to avoid duplication.

Signed-off-by: Eric Dumazet 
Cc: Arjun Roy 
Cc: Wei Wang 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2021-01-29T01:09:31+00:00

drivers/net/can/dev.c
  b552766c872f ("can: dev: prevent potential information leak in can_fill_info()")
  3e77f70e7345 ("can: dev: move driver related infrastructure into separate subdir")
  0a042c6ec991 ("can: dev: move netlink related code into seperate file")

  Code move.

drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
  57ac4a31c483 ("net/mlx5e: Correctly handle changing the number of queues when the interface is down")
  214baf22870c ("net/mlx5e: Support HTB offload")

  Adjacent code changes

net/switchdev/switchdev.c
  20776b465c0c ("net: switchdev: don't set port_obj_info->handled true when -EOPNOTSUPP")
  ffb68fc58e96 ("net: switchdev: remove the transaction structure from port object notifiers")
  bae33f2b5afe ("net: switchdev: remove the transaction structure from port attributes")

  Transaction parameter gets dropped otherwise keep the fix.

Signed-off-by: Jakub Kicinski

tcp: fix TLP timer not set when CA_STATE changes from DISORDER to OPEN

2021-01-24T05:33:01+00:00

Upon receiving a cumulative ACK that changes the congestion state from
Disorder to Open, the TLP timer is not set. If the sender is app-limited,
it can only wait for the RTO timer to expire and retransmit.

The reason for this is that the TLP timer is set before the congestion
state changes in tcp_ack(), so we delay the time point of calling
tcp_set_xmit_timer() until after tcp_fastretrans_alert() returns and
remove the FLAG_SET_XMIT_TIMER from ack_flag when the RACK reorder timer
is set.

This commit has two additional benefits:
1) Make sure to reset RTO according to RFC6298 when receiving ACK, to
avoid spurious RTO caused by RTO timer early expires.
2) Reduce the xmit timer reschedule once per ACK when the RACK reorder
timer is set.

Fixes: df92c8394e6e ("tcp: fix xmit timer to only be reset if data ACKed/SACKed")
Link: https://lore.kernel.org/netdev/1611311242-6675-1-git-send-email-yangpc@wangsu.com
Signed-off-by: Pengcheng Yang 
Acked-by: Neal Cardwell 
Acked-by: Yuchung Cheng 
Cc: Eric Dumazet 
Link: https://lore.kernel.org/r/1611464834-23030-1-git-send-email-yangpc@wangsu.com
Signed-off-by: Jakub Kicinski

tcp: make TCP_USER_TIMEOUT accurate for zero window probes

2021-01-24T03:32:51+00:00

The TCP_USER_TIMEOUT is checked by the 0-window probe timer. As the
timer has backoff with a max interval of about two minutes, the
actual timeout for TCP_USER_TIMEOUT can be off by up to two minutes.

In this patch the TCP_USER_TIMEOUT is made more accurate by taking it
into account when computing the timer value for the 0-window probes.

This patch is similar to and builds on top of the one that made
TCP_USER_TIMEOUT accurate for RTOs in commit b701a99e431d ("tcp: Add
tcp_clamp_rto_to_user_timeout() helper to improve accuracy").

Fixes: 9721e709fa68 ("tcp: simplify window probe aborting on USER_TIMEOUT")
Signed-off-by: Enke Chen 
Reviewed-by: Neal Cardwell 
Signed-off-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20210122191306.GA99540@localhost.localdomain
Signed-off-by: Jakub Kicinski

tcp: add TTL to SCM_TIMESTAMPING_OPT_STATS

2021-01-23T02:20:52+00:00

This patch adds TCP_NLA_TTL to SCM_TIMESTAMPING_OPT_STATS that exports
the time-to-live or hop limit of the latest incoming packet with
SCM_TSTAMP_ACK. The value exported may not be from the packet that acks
the sequence when incoming packets are aggregated. Exporting the
time-to-live or hop limit value of incoming packets helps to estimate
the hop count of the path of the flow that may change over time.

Signed-off-by: Yousuk Seung 
Signed-off-by: Eric Dumazet 
Signed-off-by: Neal Cardwell 
Link: https://lore.kernel.org/r/20210120204155.552275-1-ysseung@google.com
Signed-off-by: Jakub Kicinski

tcp: fix TCP socket rehash stats mis-accounting

2021-01-20T03:47:20+00:00

The previous commit 32efcc06d2a1 ("tcp: export count for rehash attempts")
would mis-account rehashing SNMP and socket stats:

  a. During handshake of an active open, only counts the first
     SYN timeout

  b. After handshake of passive and active open, stop updating
     after (roughly) TCP_RETRIES1 recurring RTOs

  c. After the socket aborts, over count timeout_rehash by 1

This patch fixes this by checking the rehash result from sk_rethink_txhash.

Fixes: 32efcc06d2a1 ("tcp: export count for rehash attempts")
Signed-off-by: Yuchung Cheng 
Signed-off-by: Eric Dumazet 
Signed-off-by: Neal Cardwell 
Link: https://lore.kernel.org/r/20210119192619.1848270-1-ycheng@google.com
Signed-off-by: Jakub Kicinski

tcp: fix TCP_USER_TIMEOUT with zero window

2021-01-19T03:59:17+00:00

The TCP session does not terminate with TCP_USER_TIMEOUT when data
remain untransmitted due to zero window.

The number of unanswered zero-window probes (tcp_probes_out) is
reset to zero with incoming acks irrespective of the window size,
as described in tcp_probe_timer():

    RFC 1122 4.2.2.17 requires the sender to stay open indefinitely
    as long as the receiver continues to respond probes. We support
    this by default and reset icsk_probes_out with incoming ACKs.

This counter, however, is the wrong one to be used in calculating the
duration that the window remains closed and data remain untransmitted.
Thanks to Jonathan Maxwell  for diagnosing the
actual issue.

In this patch a new timestamp is introduced for the socket in order to
track the elapsed time for the zero-window probes that have not been
answered with any non-zero window ack.

Fixes: 9721e709fa68 ("tcp: simplify window probe aborting on USER_TIMEOUT")
Reported-by: William McCall 
Co-developed-by: Neal Cardwell 
Signed-off-by: Neal Cardwell 
Signed-off-by: Enke Chen 
Reviewed-by: Yuchung Cheng 
Reviewed-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20210115223058.GA39267@localhost.localdomain
Signed-off-by: Jakub Kicinski

tcp: Add logic to check for SYN w/ data in tcp_simple_retransmit

2020-12-15T03:29:55+00:00

There are cases where a fastopen SYN may trigger either a ICMP_TOOBIG
message in the case of IPv6 or a fragmentation request in the case of
IPv4. This results in the socket stalling for a second or more as it does
not respond to the message by retransmitting the SYN frame.

Normally a SYN frame should not be able to trigger a ICMP_TOOBIG or
ICMP_FRAG_NEEDED however in the case of fastopen we can have a frame that
makes use of the entire MSS. In the case of fastopen it does, and an
additional complication is that the retransmit queue doesn't contain the
original frames. As a result when tcp_simple_retransmit is called and
walks the list of frames in the queue it may not mark the frames as lost
because both the SYN and the data packet each individually are smaller than
the MSS size after the adjustment. This results in the socket being stalled
until the retransmit timer kicks in and forces the SYN frame out again
without the data attached.

In order to resolve this we can reduce the MSS the packets are compared
to in tcp_simple_retransmit to -1 for cases where we are still in the
TCP_SYN_SENT state for a fastopen socket. Doing this we will mark all of
the packets related to the fastopen SYN as lost.

Signed-off-by: Alexander Duyck 
Signed-off-by: Eric Dumazet 
Signed-off-by: Yuchung Cheng 
Link: https://lore.kernel.org/r/160780498125.3272.15437756269539236825.stgit@localhost.localdomain
Signed-off-by: Jakub Kicinski

tcp: parse mptcp options contained in reset packets

2020-12-15T01:30:06+00:00

Because TCP-level resets only affect the subflow, there is a MPTCP
option to indicate that the MPTCP-level connection should be closed
immediately without a mptcp-level fin exchange.

This is the 'MPTCP fast close option'.  It can be carried on ack
segments or TCP resets.  In the latter case, its needed to parse mptcp
options also for reset packets so that MPTCP can act accordingly.

Next patch will add receive side fastclose support in MPTCP.

Acked-by: Matthieu Baerts 
Signed-off-by: Florian Westphal 
Signed-off-by: Mat Martineau 
Signed-off-by: Jakub Kicinski