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  1. 30 1月, 2013 1 次提交
  3. 18 1月, 2013 1 次提交
    • J
      net: increase fragment memory usage limits · c2a93660
      由 Jesper Dangaard Brouer 提交于 
      Increase the amount of memory usage limits for incomplete
IP fragments.

Arguing for new thresh high/low values:

 High threshold = 4 MBytes
 Low  threshold = 3 MBytes

The fragmentation memory accounting code, tries to account for the
real memory usage, by measuring both the size of frag queue struct
(inet_frag_queue (ipv4:ipq/ipv6:frag_queue)) and the SKB's truesize.

We want to be able to handle/hold-on-to enough fragments, to ensure
good performance, without causing incomplete fragments to hurt
scalability, by causing the number of inet_frag_queue to grow too much
(resulting longer searches for frag queues).

For IPv4, how much memory does the largest frag consume.

Maximum size fragment is 64K, which is approx 44 fragments with
MTU(1500) sized packets. Sizeof(struct ipq) is 200.  A 1500 byte
packet results in a truesize of 2944 (not 2048 as I first assumed)

  (44*2944)+200 = 129736 bytes

The current default high thresh of 262144 bytes, is obviously
problematic, as only two 64K fragments can fit in the queue at the
same time.

How many 64K fragment can we fit into 4 MBytes:

  4*2^20/((44*2944)+200) = 32.34 fragment in queues

An attacker could send a separate/distinct fake fragment packets per
queue, causing us to allocate one inet_frag_queue per packet, and thus
attacking the hash table and its lists.

How many frag queue do we need to store, and given a current hash size
of 64, what is the average list length.

Using one MTU sized fragment per inet_frag_queue, each consuming
(2944+200) 3144 bytes.

  4*2^20/(2944+200) = 1334 frag queues -> 21 avg list length

An attack could send small fragments, the smallest packet I could send
resulted in a truesize of 896 bytes (I'm a little surprised by this).

  4*2^20/(896+200)  = 3827 frag queues -> 59 avg list length

When increasing these number, we also need to followup with
improvements, that is going to help scalability.  Simply increasing
the hash size, is not enough as the current implementation does not
have a per hash bucket locking.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c2a93660
  5. 11 12月, 2012 1 次提交
  7. 19 11月, 2012 1 次提交
  9. 20 9月, 2012 1 次提交
  11. 27 8月, 2012 1 次提交
  13. 27 7月, 2012 1 次提交
  15. 21 7月, 2012 1 次提交
  17. 28 6月, 2012 2 次提交
    • D
      Revert "ipv4: tcp: dont cache unconfirmed intput dst" · c10237e0
      由 David S. Miller 提交于 
      This reverts commit c074da28.

This change has several unwanted side effects:

1) Sockets will cache the DST_NOCACHE route in sk->sk_rx_dst and we'll
   thus never create a real cached route.

2) All TCP traffic will use DST_NOCACHE and never use the routing
   cache at all.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c10237e0
    • E
      ipv4: tcp: dont cache unconfirmed intput dst · c074da28
      由 Eric Dumazet 提交于 
      DDOS synflood attacks hit badly IP route cache.

On typical machines, this cache is allowed to hold up to 8 Millions dst
entries, 256 bytes for each, for a total of 2GB of memory.

rt_garbage_collect() triggers and tries to cleanup things.

Eventually route cache is disabled but machine is under fire and might
OOM and crash.

This patch exploits the new TCP early demux, to set a nocache
boolean in case incoming TCP frame is for a not yet ESTABLISHED or
TIMEWAIT socket.

This 'nocache' boolean is then used in case dst entry is not found in
route cache, to create an unhashed dst entry (DST_NOCACHE)

SYN-cookie-ACK sent use a similar mechanism (ipv4: tcp: dont cache
output dst for syncookies), so after this patch, a machine is able to
absorb a DDOS synflood attack without polluting its IP route cache.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Hans Schillstrom <hans.schillstrom@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c074da28
  19. 10 6月, 2012 1 次提交
  21. 09 6月, 2012 1 次提交
  23. 20 5月, 2012 1 次提交
  25. 18 5月, 2012 1 次提交
  27. 16 5月, 2012 1 次提交
  29. 21 4月, 2012 2 次提交
  31. 20 4月, 2012 1 次提交
  33. 13 3月, 2012 1 次提交
  35. 12 3月, 2012 1 次提交
    • J
      net: Convert printks to pr_<level> · 058bd4d2
      由 Joe Perches 提交于 
      Use a more current kernel messaging style.

Convert a printk block to print_hex_dump.
Coalesce formats, align arguments.
Use %s, __func__ instead of embedding function names.

Some messages that were prefixed with <foo>_close are
now prefixed with <foo>_fini.  Some ah4 and esp messages
are now not prefixed with "ip ".

The intent of this patch is to later add something like
  #define pr_fmt(fmt) "IPv4: " fmt.
to standardize the output messages.

Text size is trivially reduced. (x86-32 allyesconfig)

$ size net/ipv4/built-in.o*
   text	   data	    bss	    dec	    hex	filename
 887888	  31558	 249696	1169142	 11d6f6	net/ipv4/built-in.o.new
 887934	  31558	 249800	1169292	 11d78c	net/ipv4/built-in.o.old
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      058bd4d2
  37. 02 12月, 2011 1 次提交
  39. 19 10月, 2011 2 次提交
  41. 06 7月, 2011 1 次提交
  43. 18 5月, 2011 1 次提交
  45. 17 5月, 2011 1 次提交
  47. 05 5月, 2011 1 次提交
    • E
      net: ip_expire() must revalidate route · 64f3b9e2
      由 Eric Dumazet 提交于 
      Commit 4a94445c (net: Use ip_route_input_noref() in input path)
added a bug in IP defragmentation handling, in case timeout is fired.

When a frame is defragmented, we use last skb dst field when building
final skb. Its dst is valid, since we are in rcu read section.

But if a timeout occurs, we take first queued fragment to build one ICMP
TIME EXCEEDED message. Problem is all queued skb have weak dst pointers,
since we escaped RCU critical section after their queueing. icmp_send()
might dereference a now freed (and possibly reused) part of memory.

Calling skb_dst_drop() and ip_route_input_noref() to revalidate route is
the only possible choice.
Reported-by: NDenys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      64f3b9e2
  49. 07 1月, 2011 1 次提交
    • E
      ipv4: IP defragmentation must be ECN aware · 6623e3b2
      由 Eric Dumazet 提交于 
      RFC3168 (The Addition of Explicit Congestion Notification to IP)
states :

5.3.  Fragmentation

   ECN-capable packets MAY have the DF (Don't Fragment) bit set.
   Reassembly of a fragmented packet MUST NOT lose indications of
   congestion.  In other words, if any fragment of an IP packet to be
   reassembled has the CE codepoint set, then one of two actions MUST be
   taken:

      * Set the CE codepoint on the reassembled packet.  However, this
        MUST NOT occur if any of the other fragments contributing to
        this reassembly carries the Not-ECT codepoint.

      * The packet is dropped, instead of being reassembled, for any
        other reason.

This patch implements this requirement for IPv4, choosing the first
action :

If one fragment had NO-ECT codepoint
        reassembled frame has NO-ECT
ElIf one fragment had CE codepoint
        reassembled frame has CE
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      6623e3b2
  51. 01 12月, 2010 1 次提交
  53. 24 9月, 2010 1 次提交
  55. 23 8月, 2010 1 次提交
  57. 13 7月, 2010 1 次提交
  59. 01 7月, 2010 1 次提交
    • C
      fragment: add fast path for in-order fragments · d6bebca9
      由 Changli Gao 提交于 
      add fast path for in-order fragments

As the fragments are sent in order in most of OSes, such as Windows, Darwin and
FreeBSD, it is likely the new fragments are at the end of the inet_frag_queue.
In the fast path, we check if the skb at the end of the inet_frag_queue is the
prev we expect.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
----
 include/net/inet_frag.h |    1 +
 net/ipv4/ip_fragment.c  |   12 ++++++++++++
 net/ipv6/reassembly.c   |   11 +++++++++++
 3 files changed, 24 insertions(+)
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d6bebca9
  61. 16 6月, 2010 2 次提交
  63. 30 3月, 2010 1 次提交
    • T
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      由 Tejun Heo 提交于 
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  65. 03 2月, 2010 1 次提交
  67. 23 1月, 2010 1 次提交
    • S
      IP: Send an ICMP "Fragment Reassembly Timeout" message when enabling connection track · e9017b55
      由 Shan Wei 提交于 
      No matter whether connection track is enabled, an end host should send 
an ICMPv4 "Fragment Reassembly Timeout" message when defrag timeout. 
The reasons are following two points:  

1. RFC 792 says:
   >>>> >> > >   If a host reassembling a fragmented datagram cannot complete the
   >>>> >> > >   reassembly due to missing fragments within its time limit it
   >>>> >> > >   discards the datagram, and it may send a time exceeded message.
   >>>> >> > > 
   >>>> >> > >   If fragment zero is not available then no time exceeded need be
   >>>> >> > >   sent at all.
   >>>> >> > > 
   >>>> >> > > Read more: http://www.faqs.org/rfcs/rfc792.html#ixzz0aOXRD7Wp

2. Patrick McHardy also agrees with this opinion.   :-)   
   About the discussion of this opinion, refer to http://patchwork.ozlabs.org/patch/41649

The patch fixed the problem like this:
When enabling connection track, fragments are received at PRE_ROUTING HOOK.
If they are failed to reassemble, ip_expire() will be called. 
Before sending an ICMP "Fragment Reassembly Timeout" message, 
the patch searches router table to get the destination entry only for host type.

The patch has been tested on both host type and route type.
Signed-off-by: NShan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      e9017b55
  69. 18 1月, 2010 1 次提交
  71. 30 11月, 2009 1 次提交