As noticed by Jon Masters <jonathan@jonmasters.org>, the conntrack hash
size is global and not per namespace, but modifiable at runtime through
/sys/module/nf_conntrack/hashsize. Changing the hash size will only
resize the hash in the current namespace however, so other namespaces
will use an invalid hash size. This can cause crashes when enlarging
the hashsize, or false negative lookups when shrinking it.

Move the hash size into the per-namespace data and only use the global
hash size to initialize the per-namespace value when instanciating a
new namespace. Additionally restrict hash resizing to init_net for
now as other namespaces are not handled currently.

Cc: stable@kernel.org
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

nf_conntrack_cachep is currently shared by all netns instances, but
because of SLAB_DESTROY_BY_RCU special semantics, this is wrong.

If we use a shared slab cache, one object can instantly flight between
one hash table (netns ONE) to another one (netns TWO), and concurrent
reader (doing a lookup in netns ONE, 'finding' an object of netns TWO)
can be fooled without notice, because no RCU grace period has to be
observed between object freeing and its reuse.

We dont have this problem with UDP/TCP slab caches because TCP/UDP
hashtables are global to the machine (and each object has a pointer to
its netns).

If we use per netns conntrack hash tables, we also *must* use per netns
conntrack slab caches, to guarantee an object can not escape from one
namespace to another one.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
[Patrick: added unique slab name allocation]
Cc: stable@kernel.org
Signed-off-by: NPatrick McHardy <kaber@trash.net>

As discovered by Jon Masters <jonathan@jonmasters.org>, the "untracked"
conntrack, which is located in the data section, might be accidentally
freed when a new namespace is instantiated while the untracked conntrack
is attached to a skb because the reference count it re-initialized.

The best fix would be to use a seperate untracked conntrack per
namespace since it includes a namespace pointer. Unfortunately this is
not possible without larger changes since the namespace is not easily
available everywhere we need it. For now move the untracked conntrack
initialization to the init_net setup function to make sure the reference
count is not re-initialized and handle cleanup in the init_net cleanup
function to make sure namespaces can exit properly while the untracked
conntrack is in use in other namespaces.

Cc: stable@kernel.org
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Vitezslav Samel discovered that since 2.6.30.4+ active FTP can not work
over NAT. The "cause" of the problem was a fix of unacknowledged data
detection with NAT (commit a3a9f79e).
However, actually, that fix uncovered a long standing bug in TCP conntrack:
when NAT was enabled, we simply updated the max of the right edge of
the segments we have seen (td_end), by the offset NAT produced with
changing IP/port in the data. However, we did not update the other parameter
(td_maxend) which is affected by the NAT offset. Thus that could drift
away from the correct value and thus resulted breaking active FTP.

The patch below fixes the issue by *not* updating the conntrack parameters
from NAT, but instead taking into account the NAT offsets in conntrack in a
consistent way. (Updating from NAT would be more harder and expensive because
it'd need to re-calculate parameters we already calculated in conntrack.)
Signed-off-by: NJozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

After m68k's task_thread_info() doesn't refer to current,
it's possible to remove sched.h from interrupt.h and not break m68k!
Many thanks to Heiko Carstens for allowing this.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>

Sizing of memory allocations shouldn't depend on the number of physical
pages found in a system, as that generally includes (perhaps a huge amount
of) non-RAM pages.  The amount of what actually is usable as storage
should instead be used as a basis here.

Some of the calculations (i.e.  those not intending to use high memory)
should likely even use (totalram_pages - totalhigh_pages).
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Conntracks in netns other than init_net dying list were never killed.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Signed-off-by: NPatrick McHardy <kaber@trash.net>

When a slab cache uses SLAB_DESTROY_BY_RCU, we must be careful when allocating
objects, since slab allocator could give a freed object still used by lockless
readers.

In particular, nf_conntrack RCU lookups rely on ct->tuplehash[xxx].hnnode.next
being always valid (ie containing a valid 'nulls' value, or a valid pointer to next
object in hash chain.)

kmem_cache_zalloc() setups object with NULL values, but a NULL value is not valid
for ct->tuplehash[xxx].hnnode.next.

Fix is to call kmem_cache_alloc() and do the zeroing ourself.

As spotted by Patrick, we also need to make sure lookup keys are committed to
memory before setting refcount to 1, or a lockless reader could get a reference
on the old version of the object. Its key re-check could then pass the barrier.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

The RCU protected conntrack hash lookup only checks whether the entry
has a refcount of zero to decide whether it is stale. This is not
sufficient, entries are explicitly removed while there is at least
one reference left, possibly more. Explicitly check whether the entry
has been marked as dying to fix this.
Signed-off-by: NPatrick McHardy <kaber@trash.net>

New connection tracking entries are inserted into the hash before they
are fully set up, namely the CONFIRMED bit is not set and the timer not
started yet. This can theoretically lead to a race with timer, which
would set the timeout value to a relative value, most likely already in
the past.

Perform hash insertion as the final step to fix this.
Signed-off-by: NPatrick McHardy <kaber@trash.net>

death_by_timeout() might delete a conntrack from hash list
and insert it in dying list.

 nf_ct_delete_from_lists(ct);
 nf_ct_insert_dying_list(ct);

I believe a (lockless) reader could *catch* ct while doing a lookup
and miss the end of its chain.
(nulls lookup algo must check the null value at the end of lookup and
should restart if the null value is not the expected one.
cf Documentation/RCU/rculist_nulls.txt for details)

We need to change nf_conntrack_init_net() and use a different "null" value,
guaranteed not being used in regular lists. Choose very large values, since
hash table uses [0..size-1] null values.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

This patch improves ctnetlink event reliability if one broadcast
listener has set the NETLINK_BROADCAST_ERROR socket option.

The logic is the following: if an event delivery fails, we keep
the undelivered events in the missed event cache. Once the next
packet arrives, we add the new events (if any) to the missed
events in the cache and we try a new delivery, and so on. Thus,
if ctnetlink fails to deliver an event, we try to deliver them
once we see a new packet. Therefore, we may lose state
transitions but the userspace process gets in sync at some point.

At worst case, if no events were delivered to userspace, we make
sure that destroy events are successfully delivered. Basically,
if ctnetlink fails to deliver the destroy event, we remove the
conntrack entry from the hashes and we insert them in the dying
list, which contains inactive entries. Then, the conntrack timer
is added with an extra grace timeout of random32() % 15 seconds
to trigger the event again (this grace timeout is tunable via
/proc). The use of a limited random timeout value allows
distributing the "destroy" resends, thus, avoiding accumulating
lots "destroy" events at the same time. Event delivery may
re-order but we can identify them by means of the tuple plus
the conntrack ID.

The maximum number of conntrack entries (active or inactive) is
still handled by nf_conntrack_max. Thus, we may start dropping
packets at some point if we accumulate a lot of inactive conntrack
entries that did not successfully report the destroy event to
userspace.

During my stress tests consisting of setting a very small buffer
of 2048 bytes for conntrackd and the NETLINK_BROADCAST_ERROR socket
flag, and generating lots of very small connections, I noticed
very few destroy entries on the fly waiting to be resend.

A simple way to test this patch consist of creating a lot of
entries, set a very small Netlink buffer in conntrackd (+ a patch
which is not in the git tree to set the BROADCAST_ERROR flag)
and invoke `conntrack -F'.

For expectations, no changes are introduced in this patch.
Currently, event delivery is only done for new expectations (no
events from expectation expiration, removal and confirmation).
In that case, they need a per-expectation event cache to implement
the same idea that is exposed in this patch.

This patch can be useful to provide reliable flow-accouting. We
still have to add a new conntrack extension to store the creation
and destroy time.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

This patch moves the helper destruction to a function that lives
in nf_conntrack_helper.c. This new function is used in the patch
to add ctnetlink reliable event delivery.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

This patch reworks the per-cpu event caching to use the conntrack
extension infrastructure.

The main drawback is that we consume more memory per conntrack
if event delivery is enabled. This patch is required by the
reliable event delivery that follows to this patch.

BTW, this patch allows you to enable/disable event delivery via
/proc/sys/net/netfilter/nf_conntrack_events in runtime, although
you can still disable event caching as compilation option.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Use mod_timer_pending() instead of atomic sequence of del_timer()/
add_timer(). mod_timer_pending() does not rearm an inactive timer,
so we don't need the conntrack lock anymore to make sure we don't
accidentally rearm a timer of a conntrack which is in the process
of being destroyed.

With this change, we don't need to take the global lock anymore at all,
counter updates can be performed under the per-conntrack lock.
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Introduce per-conntrack locks and use them instead of the global protocol
locks to avoid contention. Especially tcp_lock shows up very high in
profiles on larger machines.

This will also allow to simplify the upcoming reliable event delivery patches.
Signed-off-by: NPatrick McHardy <kaber@trash.net>

This patch simplifies the conntrack event caching system by removing
several events:

 * IPCT_[*]_VOLATILE, IPCT_HELPINFO and IPCT_NATINFO has been deleted
   since the have no clients.
 * IPCT_COUNTER_FILLING which is a leftover of the 32-bits counter
   days.
 * IPCT_REFRESH which is not of any use since we always include the
   timeout in the messages.

After this patch, the existing events are:

 * IPCT_NEW, IPCT_RELATED and IPCT_DESTROY, that are used to identify
 addition and deletion of entries.
 * IPCT_STATUS, that notes that the status bits have changes,
 eg. IPS_SEEN_REPLY and IPS_ASSURED.
 * IPCT_PROTOINFO, that reports that internal protocol information has
 changed, eg. the TCP, DCCP and SCTP protocol state.
 * IPCT_HELPER, that a helper has been assigned or unassigned to this
 entry.
 * IPCT_MARK and IPCT_SECMARK, that reports that the mark has changed, this
 covers the case when a mark is set to zero.
 * IPCT_NATSEQADJ, to report that there's updates in the NAT sequence
 adjustment.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

During the module removal there are no possible event listeners
since ctnetlink must be removed before to allow removing
nf_conntrack. This patch removes the event reporting for the
module removal case which is not of any use in the existing code.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Usefull for all protocols which do not add additional data, such
as GRE or UDPlite.
Signed-off-by: NHolger Eitzenberger <holger@eitzenberger.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Use "hlist_nulls" infrastructure we added in 2.6.29 for RCUification of UDP & TCP.

This permits an easy conversion from call_rcu() based hash lists to a
SLAB_DESTROY_BY_RCU one.

Avoiding call_rcu() delay at nf_conn freeing time has numerous gains.

First, it doesnt fill RCU queues (up to 10000 elements per cpu).
This reduces OOM possibility, if queued elements are not taken into account
This reduces latency problems when RCU queue size hits hilimit and triggers
emergency mode.

- It allows fast reuse of just freed elements, permitting better use of
CPU cache.

- We delete rcu_head from "struct nf_conn", shrinking size of this structure
by 8 or 16 bytes.

This patch only takes care of "struct nf_conn".
call_rcu() is still used for less critical conntrack parts, that may
be converted later if necessary.
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Using hlist_add_head() in nf_conntrack_set_hashsize() is quite dangerous.
Without any barrier, one CPU could see a loop while doing its lookup.
Its true new table cannot be seen by another cpu, but previous table is still
readable.
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

We use RCU to defer freeing of conntrack structures. In DOS situation, RCU might
accumulate about 10.000 elements per CPU in its internal queues. To get accurate
conntrack counts (at the expense of slightly more RAM used), we might consider
conntrack counter not taking into account "about to be freed elements, waiting
in RCU queues". We thus decrement it in nf_conntrack_free(), not in the RCU
callback.
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Tested-by: NJoakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

We currently use the negative value in the conntrack code to encode
the packet verdict in the error. As NF_DROP is equal to 0, inverting
NF_DROP makes no sense and, as a result, no packets are ever dropped.
Signed-off-by: NChristoph Paasch <christoph.paasch@gmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Since tcp_packet() may return -NF_DROP in two situations, the
packet-drop stats must be increased.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

get_random_bytes() is sometimes called with a hard coded size assumption
of an integer. This could not be true for next centuries. This patch
replace it with a compile time statement.
Signed-off-by: NHagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Table size is defined as unsigned, wheres the table maximum size is
defined as a signed integer. The calculation of max is 8 or 4,
multiplied the table size. Therefore the max value is aligned to
unsigned.
Signed-off-by: NHagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

nf_conntrack_alloc cannot return NULL, so there is no need to check for
NULL before using the value.  I have also removed the initialization of ct
to NULL in nf_conntrack_alloc, since the value is never used, and since
perhaps it might lead one to think that return ct at the end might return
NULL.

The semantic patch that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@match exists@
expression x, E;
position p1,p2;
statement S1, S2;
@@

x@p1 = nf_conntrack_alloc(...)
... when != x = E
(
  if (x@p2 == NULL || ...) S1 else S2
|
  if (x@p2 == NULL && ...) S1 else S2
)

@other_match exists@
expression match.x, E1, E2;
position p1!=match.p1,match.p2;
@@

x@p1 = E1
... when != x = E2
x@p2

@ script:python depends on !other_match@
p1 << match.p1;
p2 << match.p2;
@@

print "%s: call to nf_conntrack_alloc %s bad test %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Conntrack creation through ctnetlink has two races:

- the timer may expire and free the conntrack concurrently, causing an
  invalid memory access when attempting to put it in the hash tables

- an identical conntrack entry may be created in the packet processing
  path in the time between the lookup and hash insertion

Hold the conntrack lock between the lookup and insertion to avoid this.
Reported-by: NZoltan Borbely <bozo@andrews.hu>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netfilter/nf_conntrack_core.c:46:1: warning: symbol 'nfnetlink_parse_nat_setup_hook' was not declared. Should it be static?

Including the proper header also revealed an incorrect prototype.
Signed-off-by: NPatrick McHardy <kaber@trash.net>

As for now, the creation and update of conntracks via ctnetlink do not
propagate an event to userspace. This can result in inconsistent situations
if several userspace processes modify the connection tracking table by means
of ctnetlink at the same time. Specifically, using the conntrack command
line tool and conntrackd at the same time can trigger unconsistencies.

This patch also modifies the event cache infrastructure to pass the
process PID and the ECHO flag to nfnetlink_send() to report back
to userspace if the process that triggered the change needs so.
Based on a suggestion from Patrick McHardy.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

This patch adds module loading for helpers via ctnetlink.

* Creation path: We support explicit and implicit helper assignation. For
  the explicit case, we try to load the module. If the module is correctly
  loaded and the helper is present, we return EAGAIN to re-start the
  creation. Otherwise, we return EOPNOTSUPP.
* Update path: release the spin lock, load the module and check. If it is
  present, then return EAGAIN to re-start the update.

This patch provides a refactorized function to lookup-and-set the
connection tracking helper. The function removes the exported symbol
__nf_ct_helper_find as it has not clients anymore.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

This patch removes the module dependency between ctnetlink and
nf_nat by means of an indirect call that is initialized when
nf_nat is loaded. Now, nf_conntrack_netlink only requires
nf_conntrack and nfnetlink.

This patch puts nfnetlink_parse_nat_setup_hook into the
nf_conntrack_core to avoid dependencies between ctnetlink,
nf_conntrack_ipv4 and nf_conntrack_ipv6.

This patch also introduces the function ctnetlink_change_nat
that is only invoked from the creation path. Actually, the
nat handling cannot be invoked from the update path since
this is not allowed. By introducing this function, we remove
the useless nat handling in the update path and we avoid
deadlock-prone code.

This patch also adds the required EAGAIN logic for nfnetlink.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add init_net checks to not remove kmem_caches twice and so on.

Refactor functions to split code which should be executed only for
init_net into one place.

ip_ct_attach and ip_ct_destroy assignments remain separate, because
they're separate stages in setup and teardown.

NOTE: NOTRACK code is in for-every-net part. It will be made per-netns
after we decidce how to do it correctly.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

Heh, last minute proof-reading of this patch made me think,
that this is actually unneeded, simply because "ct" pointers will be
different for different conntracks in different netns, just like they
are different in one netns.

Not so sure anymore.

[Patrick: pointers will be different, flushing can only be done while
 inactive though and thus it needs to be per netns]
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

This is cleaner, we already know conntrack to which event is relevant.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>