This patch modifies __nf_ct_try_assign_helper in a way that invalidates support
for the following scenario:
1) attach the helper A for first time when the conntrack is created
2) attach new (different) helper B due to changes the reply tuple caused by NAT
eg. port redirection from TCP/21 to TCP/5060 with both FTP and SIP helpers
loaded, which seems to be a quite unorthodox scenario.
I can provide a more elaborated patch to support this scenario but explicit
helper attachment provides a better solution for this since now the use can
attach the helpers consistently, without relying on the automatic helper
lookup magic.
This patch fixes a possible out of bound zeroing of the conntrack helper
extension if the helper B uses more memory for its private data than
helper A.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
There are good reasons to supports helpers in user-space instead:
* Rapid connection tracking helper development, as developing code
in user-space is usually faster.
* Reliability: A buggy helper does not crash the kernel. Moreover,
we can monitor the helper process and restart it in case of problems.
* Security: Avoid complex string matching and mangling in kernel-space
running in privileged mode. Going further, we can even think about
running user-space helpers as a non-root process.
* Extensibility: It allows the development of very specific helpers (most
likely non-standard proprietary protocols) that are very likely not to be
accepted for mainline inclusion in the form of kernel-space connection
tracking helpers.
This patch adds the infrastructure to allow the implementation of
user-space conntrack helpers by means of the new nfnetlink subsystem
`nfnetlink_cthelper' and the existing queueing infrastructure
(nfnetlink_queue).
I had to add the new hook NF_IP6_PRI_CONNTRACK_HELPER to register
ipv[4|6]_helper which results from splitting ipv[4|6]_confirm into
two pieces. This change is required not to break NAT sequence
adjustment and conntrack confirmation for traffic that is enqueued
to our user-space conntrack helpers.
Basic operation, in a few steps:
1) Register user-space helper by means of `nfct':
nfct helper add ftp inet tcp
[ It must be a valid existing helper supported by conntrack-tools ]
2) Add rules to enable the FTP user-space helper which is
used to track traffic going to TCP port 21.
For locally generated packets:
iptables -I OUTPUT -t raw -p tcp --dport 21 -j CT --helper ftp
For non-locally generated packets:
iptables -I PREROUTING -t raw -p tcp --dport 21 -j CT --helper ftp
3) Run the test conntrackd in helper mode (see example files under
doc/helper/conntrackd.conf
conntrackd
4) Generate FTP traffic going, if everything is OK, then conntrackd
should create expectations (you can check that with `conntrack':
conntrack -E expect
[NEW] 301 proto=6 src=192.168.1.136 dst=130.89.148.12 sport=0 dport=54037 mask-src=255.255.255.255 mask-dst=255.255.255.255 sport=0 dport=65535 master-src=192.168.1.136 master-dst=130.89.148.12 sport=57127 dport=21 class=0 helper=ftp
[DESTROY] 301 proto=6 src=192.168.1.136 dst=130.89.148.12 sport=0 dport=54037 mask-src=255.255.255.255 mask-dst=255.255.255.255 sport=0 dport=65535 master-src=192.168.1.136 master-dst=130.89.148.12 sport=57127 dport=21 class=0 helper=ftp
This confirms that our test helper is receiving packets including the
conntrack information, and adding expectations in kernel-space.
The user-space helper can also store its private tracking information
in the conntrack structure in the kernel via the CTA_HELP_INFO. The
kernel will consider this a binary blob whose layout is unknown. This
information will be included in the information that is transfered
to user-space via glue code that integrates nfnetlink_queue and
ctnetlink.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch uses the new variable length conntrack extensions.
Instead of using union nf_conntrack_help that contain all the
helper private data information, we allocate variable length
area to store the private helper data.
This patch includes the modification of all existing helpers.
It also includes a couple of include header to avoid compilation
warnings.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Explicit helper attachment via the CT target is broken with NAT
if non-standard ports are used. This problem was hidden behind
the automatic helper assignment routine. Thus, it becomes more
noticeable now that we can disable the automatic helper assignment
with Eric Leblond's:
9e8ac5a netfilter: nf_ct_helper: allow to disable automatic helper assignment
Basically, nf_conntrack_alter_reply asks for looking up the helper
up if NAT is enabled. Unfortunately, we don't have the conntrack
template at that point anymore.
Since we don't want to rely on the automatic helper assignment,
we can skip the second look-up and stick to the helper that was
attached by iptables. With the CT target, the user is in full
control of helper attachment, thus, the policy is to trust what
the user explicitly configures via iptables (no automatic magic
anymore).
Interestingly, this bug was hidden by the automatic helper look-up
code. But it can be easily trigger if you attach the helper in
a non-standard port, eg.
iptables -I PREROUTING -t raw -p tcp --dport 8888 \
-j CT --helper ftp
And you disabled the automatic helper assignment.
I added the IPS_HELPER_BIT that allows us to differenciate between
a helper that has been explicitly attached and those that have been
automatically assigned. I didn't come up with a better solution
(having backward compatibility in mind).
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch allows you to disable automatic conntrack helper
lookup based on TCP/UDP ports, eg.
echo 0 > /proc/sys/net/netfilter/nf_conntrack_helper
[ Note: flows that already got a helper will keep using it even
if automatic helper assignment has been disabled ]
Once this behaviour has been disabled, you have to explicitly
use the iptables CT target to attach helper to flows.
There are good reasons to stop supporting automatic helper
assignment, for further information, please read:
http://www.netfilter.org/news.html#2012-04-03
This patch also adds one message to inform that automatic helper
assignment is deprecated and it will be removed soon (this is
spotted only once, with the first flow that gets a helper attached
to make it as less annoying as possible).
Signed-off-by: Eric Leblond <eric@regit.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch allows you to set expectfn which is specifically used
by the NAT side of most of the existing conntrack helpers.
I have added a symbol map that uses a string as key to look up for
the function that is attached to the expectation object. This is
the best solution I came out with to solve this issue.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch partially reverts:
3d058d7 netfilter: rework user-space expectation helper support
that was applied during the 3.2 development cycle.
After this patch, the tree remains just like before patch bc01bef,
that initially added the preliminary infrastructure.
I decided to partially revert this patch because the approach
that I proposed to resolve this problem is broken in NAT setups.
Moreover, a new infrastructure will be submitted for the 3.3.x
development cycle that resolve the existing issues while
providing a neat solution.
Since nobody has been seriously using this infrastructure in
user-space, the removal of this feature should affect any know
FOSS project (to my knowledge).
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
commit a9b3cd7f32 (rcu: convert uses of rcu_assign_pointer(x, NULL) to
RCU_INIT_POINTER) did a lot of incorrect changes, since it did a
complete conversion of rcu_assign_pointer(x, y) to RCU_INIT_POINTER(x,
y).
We miss needed barriers, even on x86, when y is not NULL.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This partially reworks bc01befdcf
which added userspace expectation support.
This patch removes the nf_ct_userspace_expect_list since now we
force to use the new iptables CT target feature to add the helper
extension for conntracks that have attached expectations from
userspace.
A new version of the proof-of-concept code to implement userspace
helpers from userspace is available at:
http://people.netfilter.org/pablo/userspace-conntrack-helpers/nf-ftp-helper-POC.tar.bz2
This patch also modifies the CT target to allow to set the
conntrack's userspace helper status flags. This flag is used
to tell the conntrack system to explicitly allocate the helper
extension.
This helper extension is useful to link the userspace expectations
with the master conntrack that is being tracked from one userspace
helper.
This feature fixes a problem in the current approach of the
userspace helper support. Basically, if the master conntrack that
has got a userspace expectation vanishes, the expectations point to
one invalid memory address. Thus, triggering an oops in the
expectation deletion event path.
I decided not to add a new revision of the CT target because
I only needed to add a new flag for it. I'll document in this
issue in the iptables manpage. I have also changed the return
value from EINVAL to EOPNOTSUPP if one flag not supported is
specified. Thus, in the future adding new features that only
require a new flag can be added without a new revision.
There is no official code using this in userspace (apart from
the proof-of-concept) that uses this infrastructure but there
will be some by beginning 2012.
Reported-by: Sam Roberts <vieuxtech@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
When assigning a NULL value to an RCU protected pointer, no barrier
is needed. The rcu_assign_pointer, used to handle that but will soon
change to not handle the special case.
Convert all rcu_assign_pointer of NULL value.
//smpl
@@ expression P; @@
- rcu_assign_pointer(P, NULL)
+ RCU_INIT_POINTER(P, NULL)
// </smpl>
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use is_vmalloc_addr() in nf_ct_free_hashtable() and get rid of
the vmalloc flags to indicate that a hash table has been allocated
using vmalloc().
Signed-off-by: Patrick McHardy <kaber@trash.net>
Use RCU helpers to reduce number of sparse warnings
(CONFIG_SPARSE_RCU_POINTER=y), and adds lockdep checks.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
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: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
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: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a new target for the raw table, which can be used to specify conntrack
parameters for specific connections, f.i. the conntrack helper.
The target attaches a "template" connection tracking entry to the skb, which
is used by the conntrack core when initializing a new conntrack.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Support initializing selected parameters of new conntrack entries from a
"conntrack template", which is a specially marked conntrack entry attached
to the skb.
Currently the helper and the event delivery masks can be initialized this
way.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Make sure not to assign a helper for a different network or transport
layer protocol to a connection.
Additionally change expectation deletion by helper to compare the name
directly - there might be multiple helper registrations using the same
name, currently one of them is chosen in an unpredictable manner and
only those expectations are removed.
Signed-off-by: Patrick 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: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Commit ea781f197d (netfilter: nf_conntrack: use SLAB_DESTROY_BY_RCU and)
get rid of call_rcu() was missing one conversion to the hlist_nulls
functions, causing a crash when unloading conntrack helper modules.
Reported-and-tested-by: Mariusz Kozlowski <m.kozlowski@tuxland.pl>
Signed-off-by: Patrick 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: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This is necessary in order to have an upper bound for Netlink
message calculation, which is not a problem at all, as there
are no helpers with a longer name.
Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>
Signed-off-by: Patrick 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: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
What is confirmed connection in one netns can very well be unconfirmed
in another one.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Make per-netns a) expectation hash and b) expectations count.
Expectations always belongs to netns to which it's master conntrack belong.
This is natural and doesn't bloat expectation.
Proc files and leaf users are stubbed to init_net, this is temporary.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
* make per-netns conntrack hash
Other solution is to add ->ct_net pointer to tuplehashes and still has one
hash, I tried that it's ugly and requires more code deep down in protocol
modules et al.
* propagate netns pointer to where needed, e. g. to conntrack iterators.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Introduce expectation classes and policies. An expectation class
is used to distinguish different types of expectations by the
same helper (for example audio/video/t.120). The expectation
policy is used to hold the maximum number of expectations and
the initial timeout for each class.
The individual classes are isolated from each other, which means
that for example an audio expectation will only evict other audio
expectations.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
With the RCU conversion only write_lock usages of nf_conntrack_lock are
left (except one read_lock that should actually use write_lock in the
H.323 helper). Switch to a spinlock.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
no real bugs, just misannotations cropping up
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Eliminate the last global list searched for every new connection.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch brings back the per-conntrack expectation list that was
removed around 2.6.10 to avoid walking all expectations on expectation
eviction and conntrack destruction.
As these were the last users of the global expectation list, this patch
also kills that.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Convert from the global expectation list to the hash table.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since conntrack currently allows to use masks for every bit of both
helper and expectation tuples, we can't hash them and have to keep
them on two global lists that are searched for every new connection.
This patch removes the never used ability to use masks for the
destination part of the expectation tuple and completely removes
masks from helpers since the only reasonable choice is a full
match on l3num, protonum and src.u.all.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently there is a wild mix of nf_conntrack_expect_, nf_ct_exp_,
expect_, exp_, ...
Consistently use nf_ct_ as prefix for exported functions.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Convert conntrack hash to hlists to reduce its size and cache
footprint. Since the default hashsize to max. entries ratio
sucks (1:16), this patch doesn't reduce the amount of memory
used for the hash by default, but instead uses a better ratio
of 1:8, which results in the same max. entries value.
One thing worth noting is early_drop. It really should use LRU,
so it now has to iterate over the entire chain to find the last
unconfirmed entry. Since chains shouldn't be very long and the
entire operation is very rare this shouldn't be a problem.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
When a helper module is unloaded all conntracks refering to it have their
helper pointer NULLed out, leading to lots of races. In most places this
can be fixed by proper use of RCU (they do already check for != NULL,
but in a racy way), additionally nf_conntrack_expect_related needs to
bail out when no helper is present.
Also remove two paranoid BUG_ONs in nf_conntrack_proto_gre that are racy
and not worth fixing.
Signed-off-by: Patrick McHarrdy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
- move EXPORT_SYMBOL next to exported symbol
- use EXPORT_SYMBOL_GPL since this is what the original code used
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some helpers (namely H.323) manually assign further helpers to expected
connections. This is not possible with nf_conntrack anymore since we
need to know whether a helper is used at allocation time.
Handle the helper assignment centrally, which allows to perform the
correct allocation and as a nice side effect eliminates the need
for the H.323 helper to fiddle with nf_conntrack_lock.
Mid term the allocation scheme really needs to be redesigned since
we do both the helper and expectation lookup _twice_ for every new
connection.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Adding the alignment to the size doesn't make any sense, what it
should do is align the size of the conntrack structure to the
alignment requirements of the helper structure and return an
aligned pointer in nfct_help().
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rename 'struct nf_conntrack_protocol' to 'struct nf_conntrack_l4proto' in
order to help distinguish it from 'struct nf_conntrack_l3proto'. It gets
rather confusing with 'nf_conntrack_protocol'.
Signed-off-by: Martin Josefsson <gandalf@wlug.westbo.se>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Pablo Neira Ayuso
Patrick McHardy