Commit Graph

412 Commits

Author SHA1 Message Date
Patrick McHardy
59eecdfb16 [NETFILTER]: nf_conntrack: UDPLITE support
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-14 20:48:44 -07:00
Patrick McHardy
61075af51f [NETFILTER]: nf_conntrack: mark protocols __read_mostly
Also remove two unnecessary EXPORT_SYMBOLs and move the
nf_conntrack_l3proto_ipv4 declaration to the correct file.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-14 20:48:19 -07:00
Jan Engelhardt
370786f9cf [NETFILTER]: x_tables: add connlimit match
ipt_connlimit has been sitting in POM-NG for a long time.
Here is a new shiny xt_connlimit with:

 * xtables'ified
 * will request the layer3 module
   (previously it hotdropped every packet when it was not loaded)
 * fixed: there was a deadlock in case of an OOM condition
 * support for any layer4 protocol (e.g. UDP/SCTP)
 * using jhash, as suggested by Eric Dumazet
 * ipv6 support

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-14 20:47:26 -07:00
Yasuyuki Kozakai
e2a3123fbe [NETFILTER]: nf_conntrack: Introduces nf_ct_get_tuplepr and uses it
nf_ct_get_tuple() requires the offset to transport header and that bothers
callers such as icmp[v6] l4proto modules. This introduces new function
to simplify them.

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>
2007-07-14 20:45:14 -07:00
Yasuyuki Kozakai
ffc3069048 [NETFILTER]: nf_conntrack: make l3proto->prepare() generic and renames it
The icmp[v6] l4proto modules parse headers in ICMP[v6] error to get tuple.
But they have to find the offset to transport protocol header before that.
Their processings are almost same as prepare() of l3proto modules.
This makes prepare() more generic to simplify icmp[v6] l4proto module
later.

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>
2007-07-14 20:44:50 -07:00
Yasuyuki Kozakai
d87d8469e2 [NETFILTER]: nf_conntrack: Increment error count on parsing IPv4 header
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>
2007-07-14 20:44:23 -07:00
Patrick McHardy
99d24edeb6 [NETFILTER]: {ip, nf}_conntrack_sctp: fix remotely triggerable NULL ptr dereference (CVE-2007-2876)
When creating a new connection by sending an unknown chunk type, we
don't transition to a valid state, causing a NULL pointer dereference
in sctp_packet when accessing sctp_timeouts[SCTP_CONNTRACK_NONE].

Fix by don't creating new conntrack entry if initial state is invalid.

Noticed by Vilmos Nebehaj <vilmos.nebehaj@ramsys.hu>

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 23:24:52 -07:00
Philippe De Muyter
56b3d975bb [NET]: Make all initialized struct seq_operations const.
Make all initialized struct seq_operations in net/ const

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 23:07:31 -07:00
Balazs Scheidler
5faf415352 [NETFILTER]: x_tables: add more detail to error message about match/target mask mismatch
Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:18:29 -07:00
Yasuyuki Kozakai
585426fdc5 [NETFILTER]: nf_queue: Use RCU and mutex for queue handlers
Queue handlers are registered/unregistered in only process context.

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>
2007-07-10 22:18:28 -07:00
Yasuyuki Kozakai
ce7663d84a [NETFILTER]: nfnetlink_queue: don't unregister handler of other subsystem
The queue handlers registered by ip[6]_queue.ko at initialization should
not be unregistered according to requests from userland program
using nfnetlink_queue. If we allow that, there is no way to register
the handlers of built-in ip[6]_queue again.

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>
2007-07-10 22:18:21 -07:00
Patrick McHardy
0d53778e81 [NETFILTER]: Convert DEBUGP to pr_debug
Convert DEBUGP to pr_debug and fix lots of non-compiling debug statements.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:18:20 -07:00
Patrick McHardy
342b7e3c8a [NETFILTER]: xt_helper: use RCU
The ->helper pointer is protected by RCU, no need to take
nf_conntrack_lock. Also remove excessive debugging.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:18:19 -07:00
Patrick McHardy
91e8db8006 [NETFILTER]: nf_conntrack_h323: turn some printks into DEBUGPs
Don't spam the ringbuffer with decoding errors. The only printks remaining
are for dropped packets when we're certain they are H.323.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:18:18 -07:00
Patrick McHardy
7ae7730fd6 [NETFILTER]: nf_conntrack: early_drop improvement
When the maximum number of conntrack entries is reached and a new
one needs to be allocated, conntrack tries to drop an unassured
connection from the same hash bucket the new conntrack would hash
to. Since with a properly sized hash the average number of entries
per bucket is 1, the chances of actually finding one are not very
good. This patch makes it walk the hash until a minimum number of
8 entries are checked.

Based on patch by Vasily Averin <vvs@sw.ru>.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:18:15 -07:00
Patrick McHardy
ec59a1110a [NETFILTER]: nf_conntrack: mark helpers __read_mostly
Most are __read_mostly already, this changes the remaining ones.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:18:14 -07:00
Patrick McHardy
b8a7fe6c10 [NETFILTER]: nf_conntrack_helper: use hashtable for conntrack helpers
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>
2007-07-10 22:18:13 -07:00
Patrick McHardy
f264a7df08 [NETFILTER]: nf_conntrack_expect: introduce nf_conntrack_expect_max sysct
As a last step of preventing DoS by creating lots of expectations, this
patch introduces a global maximum and a sysctl to control it. The default
is initialized to 4 * the expectation hash table size, which results in
1/64 of the default maxmimum of conntracks.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:18:12 -07:00
Patrick McHardy
b560580a13 [NETFILTER]: nf_conntrack_expect: maintain per conntrack expectation list
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>
2007-07-10 22:18:02 -07:00
Patrick McHardy
31f15875c5 [NETFILTER]: nf_conntrack_helper/nf_conntrack_netlink: convert to expectation hash
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>
2007-07-10 22:18:01 -07:00
Patrick McHardy
5d08ad440f [NETFILTER]: nf_conntrack_expect: convert proc functions to hash
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>
2007-07-10 22:18:00 -07:00
Patrick McHardy
a71c085562 [NETFILTER]: nf_conntrack: use hashtable for expectations
Currently all expectations are kept on a global list that

- needs to be searched for every new conncetion
- needs to be walked for evicting expectations when a master connection
  has reached its limit
- needs to be walked on connection destruction for connections that
  have open expectations

This is obviously not good, especially when considering helpers like
H.323 that register *lots* of expectations and can set up permanent
expectations, but it also allows for an easy DoS against firewalls
using connection tracking helpers.

Use a hashtable for expectations to avoid incurring the search overhead
for every new connection. The default hash size is 1/256 of the conntrack
hash table size, this can be overriden using a module parameter.

This patch only introduces the hash table for expectation lookups and
keeps other users to reduce the noise, the following patches will get
rid of it completely.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:59 -07:00
Patrick McHardy
e9c1b084e1 [NETFILTER]: nf_conntrack: move expectaton related init code to nf_conntrack_expect.c
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:58 -07:00
Patrick McHardy
cf6994c2b9 [NETFILTER]: nf_conntrack_netlink: sync expectation dumping with conntrack table dumping
Resync expectation table dumping code with conntrack dumping: don't
rely on the unique ID anymore since that requires to walk the list
backwards, which doesn't work with the upcoming conversion to hlists.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:57 -07:00
Patrick McHardy
4e1d4e6c5a [NETFILTER]: nf_conntrack_expect: avoid useless list walking
Don't walk the list when unexpecting an expectation, we already
have a reference and the timer check is enough to guarantee
that it still is on the list.

This comment suggests that it was copied there by mistake from
expectation eviction:

/* choose the oldest expectation to evict */

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:56 -07:00
Patrick McHardy
d4156e8cd9 [NETFILTER]: nf_conntrack: reduce masks to a subset of tuples
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>
2007-07-10 22:17:55 -07:00
Patrick McHardy
df43b4e7ca [NETFILTER]: nf_conntrack_ftp: use nf_ct_expect_init
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:54 -07:00
Patrick McHardy
6823645d60 [NETFILTER]: nf_conntrack_expect: function naming unification
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>
2007-07-10 22:17:53 -07:00
Patrick McHardy
ac565e5fc1 [NETFILTER]: nf_conntrack: export hash allocation/destruction functions
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:42 -07:00
Patrick McHardy
330f7db5e5 [NETFILTER]: nf_conntrack: remove 'ignore_conntrack' argument from nf_conntrack_find_get
All callers pass NULL, this also doesn't seem very useful for modules.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:41 -07:00
Patrick McHardy
f205c5e0c2 [NETFILTER]: nf_conntrack: use hlists for conntrack hash
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>
2007-07-10 22:17:40 -07:00
Patrick McHardy
8e5105a0c3 [NETFILTER]: nf_conntrack: round up hashsize to next multiple of PAGE_SIZE
Don't let the rest of the page go to waste.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:39 -07:00
Patrick McHardy
61eb3107cd [NETFILTER]: nf_conntrack_extend: use __read_mostly for struct nf_ct_ext_type
Also make them static.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:38 -07:00
Yasuyuki Kozakai
d8a0509a69 [NETFILTER]: nf_nat: kill global 'destroy' operation
This kills the global 'destroy' operation which was used by NAT.
Instead it uses the extension infrastructure so that multiple
extensions can register own operations.

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>
2007-07-10 22:17:36 -07:00
Yasuyuki Kozakai
dacd2a1a5c [NETFILTER]: nf_conntrack: remove old memory allocator of conntrack
Now memory space for help and NAT are allocated by extension
infrastructure.

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>
2007-07-10 22:17:35 -07:00
Yasuyuki Kozakai
ceceae1b15 [NETFILTER]: nf_conntrack: use extension infrastructure for helper
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>
2007-07-10 22:17:18 -07:00
Yasuyuki Kozakai
ecfab2c9fe [NETFILTER]: nf_conntrack: introduce extension infrastructure
Old space allocator of conntrack had problems about extensibility.
- It required slab cache per combination of extensions.
- It expected what extensions would be assigned, but it was impossible
  to expect that completely, then we allocated bigger memory object than
  really required.
- It needed to search helper twice due to lock issue.

Now basic informations of a connection are stored in 'struct nf_conn'.
And a storage for extension (helper, NAT) is allocated by kmalloc.

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>
2007-07-10 22:17:17 -07:00
Patrick McHardy
9f15c5302d [NETFILTER]: x_tables: mark matches and targets __read_mostly
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:15 -07:00
Jozsef Kadlecsik
ba9dda3ab5 [NETFILTER]: x_tables: add TRACE target
The TRACE target can be used to follow IP and IPv6 packets through
the ruleset.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick NcHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:14 -07:00
Jan Engelhardt
1b50b8a371 [NETFILTER]: Add u32 match
Along comes... xt_u32, a revamped ipt_u32 from POM-NG,
Plus:

    *	2007-06-02: added ipv6 support

    *	2007-06-05: uses kmalloc for the big buffer

    *   2007-06-05: added inversion

    *   2007-06-20: use skb_copy_bits() and get rid of the big buffer
        and lock (suggested by Pablo Neira Ayuso)

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:13 -07:00
Jan Engelhardt
7c4e36bc17 [NETFILTER]: Remove redundant parentheses/braces
Removes redundant parentheses and braces (And add one pair in a
xt_tcpudp.c macro).

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:11 -07:00
Jan Engelhardt
a47362a226 [NETFILTER]: add some consts, remove some casts
Make a number of variables const and/or remove unneeded casts.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:17:01 -07:00
Jan Engelhardt
e1931b784a [NETFILTER]: x_tables: switch xt_target->checkentry to bool
Switch the return type of target checkentry functions to boolean.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:16:59 -07:00
Jan Engelhardt
ccb79bdce7 [NETFILTER]: x_tables: switch xt_match->checkentry to bool
Switch the return type of match functions to boolean

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:16:58 -07:00
Jan Engelhardt
1d93a9cbad [NETFILTER]: x_tables: switch xt_match->match to bool
Switch the return type of match functions to boolean

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:16:57 -07:00
Jan Engelhardt
cff533ac12 [NETFILTER]: x_tables: switch hotdrop to bool
Switch the "hotdrop" variables to boolean

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:16:56 -07:00
Jing Min Zhao
558585aad0 [NETFILTER]: nf_conntrack_h323: check range first in sequence extension
Check range before checking STOP flag. This optimization may save a
nanosecond or less :)

Signed-off-by: Jing Min Zhao <zhaojingmin@vivecode.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:16:54 -07:00
Patrick McHardy
334a8132d9 [SKBUFF]: Keep track of writable header len of headerless clones
Currently NAT (and others) that want to modify cloned skbs copy them,
even if in the vast majority of cases its not necessary because the
skb is a clone made by TCP and the portion NAT wants to modify is
actually writable because TCP release the header reference before
cloning.

The problem is that there is no clean way for NAT to find out how
long the writable header area is, so this patch introduces skb->hdr_len
to hold this length. When a headerless skb is cloned skb->hdr_len
is set to the current headroom, for regular clones it is copied from
the original. A new function skb_clone_writable(skb, len) returns
whether the skb is writable up to len bytes from skb->data. To avoid
enlarging the skb the mac_len field is reduced to 16 bit and the
new hdr_len field is put in the remaining 16 bit.

I've done a few rough benchmarks of NAT (not with this exact patch,
but a very similar one). As expected it saves huge amounts of system
time in case of sendfile, bringing it down to basically the same
amount as without NAT, with sendmsg it only helps on loopback,
probably because of the large MTU.

Transmit a 1GB file using sendfile/sendmsg over eth0/lo with and
without NAT:

- sendfile eth0, no NAT:	sys     0m0.388s
- sendfile eth0, NAT:		sys     0m1.835s
- sendfile eth0: NAT + path:	sys     0m0.370s	(~ -80%)

- sendfile lo, no NAT:		sys     0m0.258s
- sendfile lo, NAT:		sys     0m2.609s
- sendfile lo, NAT + patch:	sys     0m0.260s	(~ -90%)

- sendmsg eth0, no NAT:		sys     0m2.508s
- sendmsg eth0, NAT:		sys     0m2.539s
- sendmsg eth0, NAT + patch:	sys     0m2.445s	(no change)

- sendmsg lo, no NAT:		sys	0m2.151s
- sendmsg lo, NAT:		sys     0m3.557s
- sendmsg lo, NAT + patch:	sys     0m2.159s	(~ -40%)

I expect other users can see a similar performance improvement,
packet mangling iptables targets, ipip and ip_gre come to mind ..

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:15:37 -07:00
Jing Min Zhao
25845b5155 [NETFILTER]: nf_conntrack_h323: add checking of out-of-range on choices' index values
Choices' index values may be out of range while still encoded in the fixed
length bit-field. This bug may cause access to undefined types (NULL
pointers) and thus crashes (Reported by Zhongling Wen).

This patch also adds checking of decode flag when decoding SEQUENCEs.

Signed-off-by: Jing Min Zhao <zhaojingmin@vivecode.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-05 17:40:23 -07:00
Yasuyuki Kozakai
e2d8e314ad [NETFILTER]: nfctnetlink: Don't allow to change helper
There is no realistic situation to change helper (Who wants IRC helper to
track FTP traffic ?). Moreover, if we want to do that, we need to fix race
issue by nfctnetlink and running helper. That will add overhead to packet
processing. It wouldn't pay. So this rejects the request to change
helper. The requests to add or remove helper are accepted as ever.

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>
2007-06-22 14:10:22 -07:00