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  1. 03 6月, 2017 2 次提交
  3. 01 6月, 2017 1 次提交
  5. 30 5月, 2017 4 次提交
  7. 27 5月, 2017 7 次提交
  9. 26 5月, 2017 3 次提交
    • I
      arp: fixed -Wuninitialized compiler warning · 5990baaa
      由 Ihar Hrachyshka 提交于 
      Commit 7d472a59 ("arp: always override
existing neigh entries with gratuitous ARP") introduced a compiler
warning:

net/ipv4/arp.c:880:35: warning: 'addr_type' may be used uninitialized in
this function [-Wmaybe-uninitialized]

While the code logic seems to be correct and doesn't allow the variable
to be used uninitialized, and the warning is not consistently
reproducible, it's still worth fixing it for other people not to waste
time looking at the warning in case it pops up in the build environment.
Yes, compiler is probably at fault, but we will need to accommodate.

Fixes: 7d472a59 ("arp: always override existing neigh entries with gratuitous ARP")
Signed-off-by: NIhar Hrachyshka <ihrachys@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5990baaa
    • W
      tcp: avoid fastopen API to be used on AF_UNSPEC · ba615f67
      由 Wei Wang 提交于 
      Fastopen API should be used to perform fastopen operations on the TCP
socket. It does not make sense to use fastopen API to perform disconnect
by calling it with AF_UNSPEC. The fastopen data path is also prone to
race conditions and bugs when using with AF_UNSPEC.

One issue reported and analyzed by Vegard Nossum is as follows:
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Thread A:                            Thread B:
------------------------------------------------------------------------
sendto()
 - tcp_sendmsg()
     - sk_stream_memory_free() = 0
         - goto wait_for_sndbuf
	     - sk_stream_wait_memory()
	        - sk_wait_event() // sleep
          |                          sendto(flags=MSG_FASTOPEN, dest_addr=AF_UNSPEC)
	  |                           - tcp_sendmsg()
	  |                              - tcp_sendmsg_fastopen()
	  |                                 - __inet_stream_connect()
	  |                                    - tcp_disconnect() //because of AF_UNSPEC
	  |                                       - tcp_transmit_skb()// send RST
	  |                                    - return 0; // no reconnect!
	  |                           - sk_stream_wait_connect()
	  |                                 - sock_error()
	  |                                    - xchg(&sk->sk_err, 0)
	  |                                    - return -ECONNRESET
	- ... // wake up, see sk->sk_err == 0
    - skb_entail() on TCP_CLOSE socket

If the connection is reopened then we will send a brand new SYN packet
after thread A has already queued a buffer. At this point I think the
socket internal state (sequence numbers etc.) becomes messed up.

When the new connection is closed, the FIN-ACK is rejected because the
sequence number is outside the window. The other side tries to
retransmit,
but __tcp_retransmit_skb() calls tcp_trim_head() on an empty skb which
corrupts the skb data length and hits a BUG() in copy_and_csum_bits().
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Hence, this patch adds a check for AF_UNSPEC in the fastopen data path
and return EOPNOTSUPP to user if such case happens.

Fixes: cf60af03 ("tcp: Fast Open client - sendmsg(MSG_FASTOPEN)")
Reported-by: NVegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: NWei Wang <weiwan@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ba615f67
    • E
      tcp: better validation of received ack sequences · d0e1a1b5
      由 Eric Dumazet 提交于 
      Paul Fiterau Brostean reported :

<quote>
Linux TCP stack we analyze exhibits behavior that seems odd to me.
The scenario is as follows (all packets have empty payloads, no window
scaling, rcv/snd window size should not be a factor):

       TEST HARNESS (CLIENT)                        LINUX SERVER

   1.  -                                          LISTEN (server listen,
then accepts)

   2.  - --> <SEQ=100><CTL=SYN>               --> SYN-RECEIVED

   3.  - <-- <SEQ=300><ACK=101><CTL=SYN,ACK>  <-- SYN-RECEIVED

   4.  - --> <SEQ=101><ACK=301><CTL=ACK>      --> ESTABLISHED

   5.  - <-- <SEQ=301><ACK=101><CTL=FIN,ACK>  <-- FIN WAIT-1 (server
opts to close the data connection calling "close" on the connection
socket)

   6.  - --> <SEQ=101><ACK=99999><CTL=FIN,ACK> --> CLOSING (client sends
FIN,ACK with not yet sent acknowledgement number)

   7.  - <-- <SEQ=302><ACK=102><CTL=ACK>      <-- CLOSING (ACK is 102
instead of 101, why?)

... (silence from CLIENT)

   8.  - <-- <SEQ=301><ACK=102><CTL=FIN,ACK>  <-- CLOSING
(retransmission, again ACK is 102)

Now, note that packet 6 while having the expected sequence number,
acknowledges something that wasn't sent by the server. So I would
expect
the packet to maybe prompt an ACK response from the server, and then be
ignored. Yet it is not ignored and actually leads to an increase of the
acknowledgement number in the server's retransmission of the FIN,ACK
packet. The explanation I found is that the FIN  in packet 6 was
processed, despite the acknowledgement number being unacceptable.
Further experiments indeed show that the server processes this FIN,
transitioning to CLOSING, then on receiving an ACK for the FIN it had
send in packet 5, the server (or better said connection) transitions
from CLOSING to TIME_WAIT (as signaled by netstat).

</quote>

Indeed, tcp_rcv_state_process() calls tcp_ack() but
does not exploit the @acceptable status but for TCP_SYN_RECV
state.

What we want here is to send a challenge ACK, if not in TCP_SYN_RECV
state. TCP_FIN_WAIT1 state is not the only state we should fix.

Add a FLAG_NO_CHALLENGE_ACK so that tcp_rcv_state_process()
can choose to send a challenge ACK and discard the packet instead
of wrongly change socket state.

With help from Neal Cardwell.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NPaul Fiterau Brostean <p.fiterau-brostean@science.ru.nl>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d0e1a1b5
  11. 25 5月, 2017 1 次提交
    • E
      tcp: fix TCP_SYNCNT flakes · ce682ef6
      由 Eric Dumazet 提交于 
      After the mentioned commit, some of our packetdrill tests became flaky.

TCP_SYNCNT socket option can limit the number of SYN retransmits.

retransmits_timed_out() has to compare times computations based on
local_clock() while timers are based on jiffies. With NTP adjustments
and roundings we can observe 999 ms delay for 1000 ms timers.
We end up sending one extra SYN packet.

Gimmick added in commit 6fa12c85 ("Revert Backoff [v3]: Calculate
TCP's connection close threshold as a time value") makes no
real sense for TCP_SYN_SENT sockets where no RTO backoff can happen at
all.

Lets use a simpler logic for TCP_SYN_SENT sockets and remove @syn_set
parameter from retransmits_timed_out()

Fixes: 9a568de4 ("tcp: switch TCP TS option (RFC 7323) to 1ms clock")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ce682ef6
  13. 23 5月, 2017 3 次提交
  15. 22 5月, 2017 9 次提交
  17. 20 5月, 2017 2 次提交
  19. 19 5月, 2017 1 次提交
  21. 18 5月, 2017 7 次提交