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  1. 09 10月, 2013 2 次提交
    • E
      ipv6: make lookups simpler and faster · efe4208f
      由 Eric Dumazet 提交于 
      TCP listener refactoring, part 4 :

To speed up inet lookups, we moved IPv4 addresses from inet to struct
sock_common

Now is time to do the same for IPv6, because it permits us to have fast
lookups for all kind of sockets, including upcoming SYN_RECV.

Getting IPv6 addresses in TCP lookups currently requires two extra cache
lines, plus a dereference (and memory stall).

inet6_sk(sk) does the dereference of inet_sk(__sk)->pinet6

This patch is way bigger than its IPv4 counter part, because for IPv4,
we could add aliases (inet_daddr, inet_rcv_saddr), while on IPv6,
it's not doable easily.

inet6_sk(sk)->daddr becomes sk->sk_v6_daddr
inet6_sk(sk)->rcv_saddr becomes sk->sk_v6_rcv_saddr

And timewait socket also have tw->tw_v6_daddr & tw->tw_v6_rcv_saddr
at the same offset.

We get rid of INET6_TW_MATCH() as INET6_MATCH() is now the generic
macro.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      efe4208f
    • E
      tcp/dccp: remove twchain · 05dbc7b5
      由 Eric Dumazet 提交于 
      TCP listener refactoring, part 3 :

Our goal is to hash SYN_RECV sockets into main ehash for fast lookup,
and parallel SYN processing.

Current inet_ehash_bucket contains two chains, one for ESTABLISH (and
friend states) sockets, another for TIME_WAIT sockets only.

As the hash table is sized to get at most one socket per bucket, it
makes little sense to have separate twchain, as it makes the lookup
slightly more complicated, and doubles hash table memory usage.

If we make sure all socket types have the lookup keys at the same
offsets, we can use a generic and faster lookup. It turns out TIME_WAIT
and ESTABLISHED sockets already have common lookup fields for IPv4.

[ INET_TW_MATCH() is no longer needed ]

I'll provide a follow-up to factorize IPv6 lookup as well, to remove
INET6_TW_MATCH()

This way, SYN_RECV pseudo sockets will be supported the same.

A new sock_gen_put() helper is added, doing either a sock_put() or
inet_twsk_put() [ and will support SYN_RECV later ].

Note this helper should only be called in real slow path, when rcu
lookup found a socket that was moved to another identity (freed/reused
immediately), but could eventually be used in other contexts, like
sock_edemux()

Before patch :

dmesg | grep "TCP established"

TCP established hash table entries: 524288 (order: 11, 8388608 bytes)

After patch :

TCP established hash table entries: 524288 (order: 10, 4194304 bytes)
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      05dbc7b5
  3. 04 10月, 2013 1 次提交
    • E
      tcp: shrink tcp6_timewait_sock by one cache line · 96f817fe
      由 Eric Dumazet 提交于 
      While working on tcp listener refactoring, I found that it
would really make things easier if sock_common could include
the IPv6 addresses needed in the lookups, instead of doing
very complex games to get their values (depending on sock
being SYN_RECV, ESTABLISHED, TIME_WAIT)

For this to happen, I need to be sure that tcp6_timewait_sock
and tcp_timewait_sock consume same number of cache lines.

This is possible if we only use 32bits for tw_ttd, as we remove
one 32bit hole in inet_timewait_sock

inet_tw_time_stamp() is defined and used, even if its current
implementation looks like tcp_time_stamp : We might need finer
resolution for tcp_time_stamp in the future.

Before patch : sizeof(struct tcp6_timewait_sock) = 0xc8

After patch : sizeof(struct tcp6_timewait_sock) = 0xc0
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      96f817fe
  5. 20 4月, 2013 1 次提交
  7. 12 3月, 2013 1 次提交
    • N
      tcp: Tail loss probe (TLP) · 6ba8a3b1
      由 Nandita Dukkipati 提交于 
      This patch series implement the Tail loss probe (TLP) algorithm described
in http://tools.ietf.org/html/draft-dukkipati-tcpm-tcp-loss-probe-01. The
first patch implements the basic algorithm.

TLP's goal is to reduce tail latency of short transactions. It achieves
this by converting retransmission timeouts (RTOs) occuring due
to tail losses (losses at end of transactions) into fast recovery.
TLP transmits one packet in two round-trips when a connection is in
Open state and isn't receiving any ACKs. The transmitted packet, aka
loss probe, can be either new or a retransmission. When there is tail
loss, the ACK from a loss probe triggers FACK/early-retransmit based
fast recovery, thus avoiding a costly RTO. In the absence of loss,
there is no change in the connection state.

PTO stands for probe timeout. It is a timer event indicating
that an ACK is overdue and triggers a loss probe packet. The PTO value
is set to max(2*SRTT, 10ms) and is adjusted to account for delayed
ACK timer when there is only one oustanding packet.

TLP Algorithm

On transmission of new data in Open state:
  -> packets_out > 1: schedule PTO in max(2*SRTT, 10ms).
  -> packets_out == 1: schedule PTO in max(2*RTT, 1.5*RTT + 200ms)
  -> PTO = min(PTO, RTO)

Conditions for scheduling PTO:
  -> Connection is in Open state.
  -> Connection is either cwnd limited or no new data to send.
  -> Number of probes per tail loss episode is limited to one.
  -> Connection is SACK enabled.

When PTO fires:
  new_segment_exists:
    -> transmit new segment.
    -> packets_out++. cwnd remains same.

  no_new_packet:
    -> retransmit the last segment.
       Its ACK triggers FACK or early retransmit based recovery.

ACK path:
  -> rearm RTO at start of ACK processing.
  -> reschedule PTO if need be.

In addition, the patch includes a small variation to the Early Retransmit
(ER) algorithm, such that ER and TLP together can in principle recover any
N-degree of tail loss through fast recovery. TLP is controlled by the same
sysctl as ER, tcp_early_retrans sysctl.
tcp_early_retrans==0; disables TLP and ER.
		 ==1; enables RFC5827 ER.
		 ==2; delayed ER.
		 ==3; TLP and delayed ER. [DEFAULT]
		 ==4; TLP only.

The TLP patch series have been extensively tested on Google Web servers.
It is most effective for short Web trasactions, where it reduced RTOs by 15%
and improved HTTP response time (average by 6%, 99th percentile by 10%).
The transmitted probes account for <0.5% of the overall transmissions.
Signed-off-by: NNandita Dukkipati <nanditad@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Acked-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      6ba8a3b1
  9. 10 12月, 2012 4 次提交
    • N
      inet_diag: validate port comparison byte code to prevent unsafe reads · 5e1f5420
      由 Neal Cardwell 提交于 
      Add logic to verify that a port comparison byte code operation
actually has the second inet_diag_bc_op from which we read the port
for such operations.

Previously the code blindly referenced op[1] without first checking
whether a second inet_diag_bc_op struct could fit there. So a
malicious user could make the kernel read 4 bytes beyond the end of
the bytecode array by claiming to have a whole port comparison byte
code (2 inet_diag_bc_op structs) when in fact the bytecode was not
long enough to hold both.
Signed-off-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5e1f5420
    • N
      inet_diag: avoid unsafe and nonsensical prefix matches in inet_diag_bc_run() · f67caec9
      由 Neal Cardwell 提交于 
      Add logic to check the address family of the user-supplied conditional
and the address family of the connection entry. We now do not do
prefix matching of addresses from different address families (AF_INET
vs AF_INET6), except for the previously existing support for having an
IPv4 prefix match an IPv4-mapped IPv6 address (which this commit
maintains as-is).

This change is needed for two reasons:

(1) The addresses are different lengths, so comparing a 128-bit IPv6
prefix match condition to a 32-bit IPv4 connection address can cause
us to unwittingly walk off the end of the IPv4 address and read
garbage or oops.

(2) The IPv4 and IPv6 address spaces are semantically distinct, so a
simple bit-wise comparison of the prefixes is not meaningful, and
would lead to bogus results (except for the IPv4-mapped IPv6 case,
which this commit maintains).
Signed-off-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f67caec9
    • N
      inet_diag: validate byte code to prevent oops in inet_diag_bc_run() · 405c0059
      由 Neal Cardwell 提交于 
      Add logic to validate INET_DIAG_BC_S_COND and INET_DIAG_BC_D_COND
operations.

Previously we did not validate the inet_diag_hostcond, address family,
address length, and prefix length. So a malicious user could make the
kernel read beyond the end of the bytecode array by claiming to have a
whole inet_diag_hostcond when the bytecode was not long enough to
contain a whole inet_diag_hostcond of the given address family. Or
they could make the kernel read up to about 27 bytes beyond the end of
a connection address by passing a prefix length that exceeded the
length of addresses of the given family.
Signed-off-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      405c0059
    • N
      inet_diag: fix oops for IPv4 AF_INET6 TCP SYN-RECV state · 1c95df85
      由 Neal Cardwell 提交于 
      Fix inet_diag to be aware of the fact that AF_INET6 TCP connections
instantiated for IPv4 traffic and in the SYN-RECV state were actually
created with inet_reqsk_alloc(), instead of inet6_reqsk_alloc(). This
means that for such connections inet6_rsk(req) returns a pointer to a
random spot in memory up to roughly 64KB beyond the end of the
request_sock.

With this bug, for a server using AF_INET6 TCP sockets and serving
IPv4 traffic, an inet_diag user like `ss state SYN-RECV` would lead to
inet_diag_fill_req() causing an oops or the export to user space of 16
bytes of kernel memory as a garbage IPv6 address, depending on where
the garbage inet6_rsk(req) pointed.
Signed-off-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1c95df85
  11. 04 11月, 2012 2 次提交
    • C
      net: inet_diag -- Return error code if protocol handler is missed · cacb6ba0
      由 Cyrill Gorcunov 提交于 
      We've observed that in case if UDP diag module is not
supported in kernel the netlink returns NLMSG_DONE without
notifying a caller that handler is missed.

This patch makes __inet_diag_dump to return error code instead.

So as example it become possible to detect such situation
and handle it gracefully on userspace level.
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
CC: David Miller <davem@davemloft.net>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Pavel Emelyanov <xemul@parallels.com>
Acked-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      cacb6ba0
    • E
      tcp: better retrans tracking for defer-accept · e6c022a4
      由 Eric Dumazet 提交于 
      For passive TCP connections using TCP_DEFER_ACCEPT facility,
we incorrectly increment req->retrans each time timeout triggers
while no SYNACK is sent.

SYNACK are not sent for TCP_DEFER_ACCEPT that were established (for
which we received the ACK from client). Only the last SYNACK is sent
so that we can receive again an ACK from client, to move the req into
accept queue. We plan to change this later to avoid the useless
retransmit (and potential problem as this SYNACK could be lost)

TCP_INFO later gives wrong information to user, claiming imaginary
retransmits.

Decouple req->retrans field into two independent fields :

num_retrans : number of retransmit
num_timeout : number of timeouts

num_timeout is the counter that is incremented at each timeout,
regardless of actual SYNACK being sent or not, and used to
compute the exponential timeout.

Introduce inet_rtx_syn_ack() helper to increment num_retrans
only if ->rtx_syn_ack() succeeded.

Use inet_rtx_syn_ack() from tcp_check_req() to increment num_retrans
when we re-send a SYNACK in answer to a (retransmitted) SYN.
Prior to this patch, we were not counting these retransmits.

Change tcp_v[46]_rtx_synack() to increment TCP_MIB_RETRANSSEGS
only if a synack packet was successfully queued.
Reported-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Julian Anastasov <ja@ssi.bg>
Cc: Vijay Subramanian <subramanian.vijay@gmail.com>
Cc: Elliott Hughes <enh@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      e6c022a4
  13. 24 10月, 2012 1 次提交
  15. 11 9月, 2012 1 次提交
  17. 15 8月, 2012 1 次提交
  19. 17 7月, 2012 1 次提交
    • A
      net: make sock diag per-namespace · 51d7cccf
      由 Andrey Vagin 提交于 
      Before this patch sock_diag works for init_net only and dumps
information about sockets from all namespaces.

This patch expands sock_diag for all name-spaces.
It creates a netlink kernel socket for each netns and filters
data during dumping.

v2: filter accoding with netns in all places
    remove an unused variable.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Pavel Emelyanov <xemul@parallels.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: NAndrew Vagin <avagin@openvz.org>
Acked-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      51d7cccf
  21. 28 6月, 2012 1 次提交
  23. 27 6月, 2012 1 次提交
  25. 26 4月, 2012 2 次提交
  27. 27 2月, 2012 1 次提交
  29. 12 1月, 2012 2 次提交
  31. 31 12月, 2011 1 次提交
  33. 17 12月, 2011 2 次提交
  35. 12 12月, 2011 1 次提交
  37. 10 12月, 2011 8 次提交
  39. 07 12月, 2011 6 次提交