In compliance with RFC5961, the network stack send challenge ACK in
response to spurious SYN packets, since commit 0c228e833c ("tcp:
Restore RFC5961-compliant behavior for SYN packets").
This pose a problem for netfilter conntrack in state LAST_ACK, because
this challenge ACK is (falsely) seen as ACKing last FIN, causing a
false state transition (into TIME_WAIT).
The challenge ACK is hard to distinguish from real last ACK. Thus,
solution introduce a flag that tracks the potential for seeing a
challenge ACK, in case a SYN packet is let through and current state
is LAST_ACK.
When conntrack transition LAST_ACK to TIME_WAIT happens, this flag is
used for determining if we are expecting a challenge ACK.
Scapy based reproducer script avail here:
https://github.com/netoptimizer/network-testing/blob/master/scapy/tcp_hacks_3WHS_LAST_ACK.py
Fixes: 0c228e833c ("tcp: Restore RFC5961-compliant behavior for SYN packets")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Since adding a new function to seq_file (seq_has_overflowed())
there isn't any value for functions called from seq_show to
return anything. Remove the int returns of the various
print_tuple/<foo>_print_tuple functions.
Link: http://lkml.kernel.org/p/f2e8cf8df433a197daa62cbaf124c900c708edc7.1412031505.git.joe@perches.com
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Cc: netfilter-devel@vger.kernel.org
Cc: coreteam@netfilter.org
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The seq_printf() and friends are having their return values removed.
The print_conntrack() returns the result of seq_printf(), which is
meaningless when seq_printf() returns void. Might as well remove the
return values of print_conntrack() as well.
Link: http://lkml.kernel.org/r/20141029220107.465008329@goodmis.org
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Cc: netfilter-devel@vger.kernel.org
Cc: coreteam@netfilter.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When a port that was used to listen for inbound connections gets closed
and reused for outgoing connections (like rsh ends up doing for stderr
flow), current we may reject the SYN/ACK packet for the new connection
because tcp_conntracks states forbirds a port to become a client while
there is still a TIME_WAIT entry in there for it.
As TCP may expire the TIME_WAIT socket in 60s and conntrack's timeout
for it is 120s, there is a ~60s window that the application can end up
opening a port that conntrack will end up blocking.
This patch fixes this by simply allowing such state transition: if we
see a SYN, in TIME_WAIT state, on REPLY direction, move it to sSS. Note
that the rest of the code already handles this situation, more
specificly in tcp_packet(), first switch clause.
Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add a SYNPROXY for netfilter. The code is split into two parts, the synproxy
core with common functions and an address family specific target.
The SYNPROXY receives the connection request from the client, responds with
a SYN/ACK containing a SYN cookie and announcing a zero window and checks
whether the final ACK from the client contains a valid cookie.
It then establishes a connection to the original destination and, if
successful, sends a window update to the client with the window size
announced by the server.
Support for timestamps, SACK, window scaling and MSS options can be
statically configured as target parameters if the features of the server
are known. If timestamps are used, the timestamp value sent back to
the client in the SYN/ACK will be different from the real timestamp of
the server. In order to now break PAWS, the timestamps are translated in
the direction server->client.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Tested-by: Martin Topholm <mph@one.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Split out sequence number adjustments from NAT and move them to the conntrack
core to make them usable for SYN proxying. The sequence number adjustment
information is moved to a seperate extend. The extend is added to new
conntracks when a NAT mapping is set up for a connection using a helper.
As a side effect, this saves 24 bytes per connection with NAT in the common
case that a connection does not have a helper assigned.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Tested-by: Martin Topholm <mph@one.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Conflicts:
net/netfilter/nf_conntrack_proto_tcp.c
The conflict had to do with overlapping changes dealing with
fixing the use of an "s32" to hold the value returned by
NAT_OFFSET().
Pablo Neira Ayuso says:
====================
The following batch contains Netfilter/IPVS updates for your net-next tree.
More specifically, they are:
* Trivial typo fix in xt_addrtype, from Phil Oester.
* Remove net_ratelimit in the conntrack logging for consistency with other
logging subsystem, from Patrick McHardy.
* Remove unneeded includes from the recently added xt_connlabel support, from
Florian Westphal.
* Allow to update conntracks via nfqueue, don't need NFQA_CFG_F_CONNTRACK for
this, from Florian Westphal.
* Remove tproxy core, now that we have socket early demux, from Florian
Westphal.
* A couple of patches to refactor conntrack event reporting to save a good
bunch of lines, from Florian Westphal.
* Fix missing locking in NAT sequence adjustment, it did not manifested in
any known bug so far, from Patrick McHardy.
* Change sequence number adjustment variable to 32 bits, to delay the
possible early overflow in long standing connections, also from Patrick.
* Comestic cleanups for IPVS, from Dragos Foianu.
* Fix possible null dereference in IPVS in the SH scheduler, from Daniel
Borkmann.
* Allow to attach conntrack expectations via nfqueue. Before this patch, you
had to use ctnetlink instead, thus, we save the conntrack lookup.
* Export xt_rpfilter and xt_HMARK header files, from Nicolas Dichtel.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently the conntrack checks if the ending sequence of a packet
falls within the observed receive window. However it does so even
if it has not observe any packet from the remote yet and uses an
uninitialized receive window (td_maxwin).
If a connection uses Fast Open to send a SYN-data packet which is
dropped afterward in the network. The subsequent SYNs retransmits
will all fail this check and be discarded, leading to a connection
timeout. This is because the SYN retransmit does not contain data
payload so
end == initial sequence number (isn) + 1
sender->td_end == isn + syn_data_len
receiver->td_maxwin == 0
The fix is to only apply this check after td_maxwin is initialized.
Reported-by: Michael Chan <mcfchan@stanford.edu>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Using 16 bits is too small, when many adjustments happen the offsets might
overflow and break the connection.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
When loose tracking is enabled (default), non-syn packets cause
creation of new conntracks in established state with default timeout for
established state (5 days). This causes the table to fill up with UNREPLIED
when the 'new ack' packet happened to be the last-ack of a previous,
already timed-out connection.
Consider:
A 192.168.x.52792 > 10.184.y.80: F, 426:426(0) ack 9237 win 255
B 10.184.y.80 > 192.168.x.52792: ., ack 427 win 123
<61 second pause>
C 10.184.y.80 > 192.168.x.52792: F, 9237:9237(0) ack 427 win 123
D 192.168.x.52792 > 10.184.y.80: ., ack 9238 win 255
B moves conntrack to CLOSE_WAIT and will kill it after 60 second timeout,
C is ignored (FIN set), but last packet (D) causes new ct with 5-days timeout.
Use UNACK timeout (5 minutes) instead to get rid of these entries sooner
when in ESTABLISHED state without having seen traffic in both directions.
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add copyright statements to all netfilter files which have had significant
changes done by myself in the past.
Some notes:
- nf_conntrack_ecache.c was incorrectly attributed to Rusty and Netfilter
Core Team when it got split out of nf_conntrack_core.c. The copyrights
even state a date which lies six years before it was written. It was
written in 2005 by Harald and myself.
- net/ipv{4,6}/netfilter.c, net/netfitler/nf_queue.c were missing copyright
statements. I've added the copyright statement from net/netfilter/core.c,
where this code originated
- for nf_conntrack_proto_tcp.c I've also added Jozsef, since I didn't want
it to give the wrong impression
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch adds netns support to nf_log and it prepares netns
support for existing loggers. It is composed of four major
changes.
1) nf_log_register has been split to two functions: nf_log_register
and nf_log_set. The new nf_log_register is used to globally
register the nf_logger and nf_log_set is used for enabling
pernet support from nf_loggers.
Per netns is not yet complete after this patch, it comes in
separate follow up patches.
2) Add net as a parameter of nf_log_bind_pf. Per netns is not
yet complete after this patch, it only allows to bind the
nf_logger to the protocol family from init_net and it skips
other cases.
3) Adapt all nf_log_packet callers to pass netns as parameter.
After this patch, this function only works for init_net.
4) Make the sysctl net/netfilter/nf_log pernet.
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add stricter checking for a few attributes.
Note that these changes don't fix any bug in the current code base.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Conflicts:
net/netfilter/nfnetlink_log.c
net/netfilter/xt_LOG.c
Rather easy conflict resolution, the 'net' tree had bug fixes to make
sure we checked if a socket is a time-wait one or not and elide the
logging code if so.
Whereas on the 'net-next' side we are calculating the UID and GID from
the creds using different interfaces due to the user namespace changes
from Eric Biederman.
Signed-off-by: David S. Miller <davem@davemloft.net>
We spare nothing by not validating the sequence number of dataless
ACK packets and enabling it makes harder off-path attacks.
See: "Reflection scan: an Off-Path Attack on TCP" by Jan Wrobel,
http://arxiv.org/abs/1201.2074
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Clients should not send such packets. By accepting them, we open
up a hole by wich ephemeral ports can be discovered in an off-path
attack.
See: "Reflection scan: an Off-Path Attack on TCP" by Jan Wrobel,
http://arxiv.org/abs/1201.2074
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Convert the IPv4 NAT implementation to a protocol independent core and
address family specific modules.
Signed-off-by: Patrick McHardy <kaber@trash.net>
This patch adds missing per-net support for the cttimeout
infrastructure to TCP.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Gao feng <gaofeng@cn.fujitsu.com>
This patch generalizes nf_ct_l4proto_net by splitting it into chunks and
moving the corresponding protocol part to where it really belongs to.
To clarify, note that we follow two different approaches to support per-net
depending if it's built-in or run-time loadable protocol tracker.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Gao feng <gaofeng@cn.fujitsu.com>
Merge tcpv4_net_init and tcpv6_net_init into tcp_net_init to
remove redundant code now that we have the u_int16_t proto
parameter.
And use nf_proto_net.users to identify if it's the first time
we use the nf_proto_net, in that case, we initialize it.
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
l4proto->init contain quite redundant code. We can simplify this
by adding a new parameter l3proto.
This patch prepares that code simplification.
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch fixes the compilation of the TCP and UDP trackers with sysctl
compilation disabled:
net/netfilter/nf_conntrack_proto_udp.c: In function ‘udp_init_net_data’:
net/netfilter/nf_conntrack_proto_udp.c:279:13: error: ‘struct nf_proto_net’ has no member named
‘user’
net/netfilter/nf_conntrack_proto_tcp.c:1606:9: error: ‘struct nf_proto_net’ has no member named
‘user’
net/netfilter/nf_conntrack_proto_tcp.c:1643:9: error: ‘struct nf_proto_net’ has no member named
‘user’
Reported-by: Fengguang Wu <wfg@linux.intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds namespace support for cttimeout.
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Since the sysctl data for l[3|4]proto now resides in pernet nf_proto_net.
We can now remove this unused fields from struct nf_contrack_l[3,4]proto.
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch adds namespace support for TCP protocol tracker.
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Extend log message if packets are ignored to include the TCP state, ie.
replace:
[ 3968.070196] nf_ct_tcp: invalid packet ignored IN= OUT= SRC=...
by:
[ 3968.070196] nf_ct_tcp: invalid packet ignored in state ESTABLISHED IN= OUT= SRC=...
This information is useful to know in what state we were while ignoring the
packet.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
For a picked up connection, the window win is scaled twice: one is by the
initialization code, and the other is by the sender updating code.
I use the temporary variable swin instead of modifying the variable win.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
These macros contain a hidden goto, and are thus extremely error
prone and make code hard to audit.
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the infrastructure to add fine timeout tuning
over nfnetlink. Now you can use the NFNL_SUBSYS_CTNETLINK_TIMEOUT
subsystem to create/delete/dump timeout objects that contain some
specific timeout policy for one flow.
The follow up patches will allow you attach timeout policy object
to conntrack via the CT target and the conntrack extension
infrastructure.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch defines a new interface for l4 protocol trackers:
unsigned int *(*get_timeouts)(struct net *net);
that is used to return the array of unsigned int that contains
the timeouts that will be applied for this flow. This is passed
to the l4proto->new(...) and l4proto->packet(...) functions to
specify the timeout policy.
This interface allows per-net global timeout configuration
(although only DCCP supports this by now) and it will allow
custom custom timeout configuration by means of follow-up
patches.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch moves the retransmission and unacknowledged timeouts
to the tcp_timeouts array. This change is required by follow-up
patches.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Use IS_ENABLED(CONFIG_FOO)
instead of defined(CONFIG_FOO) || defined (CONFIG_FOO_MODULE)
Signed-off-by: Igor Maravić <igorm@etf.rs>
Signed-off-by: David S. Miller <davem@davemloft.net>
The wrong multiplication of TCPOLEN_TSTAMP_ALIGNED by 4 skips the fast path
for the timestamp-only option. Bug reported by Michael M. Builov (netfilter
bugzilla #738).
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Michael M. Builov reported that in the tcp_options and tcp_sack functions
of netfilter TCP conntrack the incorrect handling of invalid TCP option
with too big opsize may lead to read access beyond tcp-packet or buffer
allocated on stack (netfilter bugzilla #738). The fix is to stop parsing
the options at detecting the broken option.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This patch fixes the out of sync scenarios while in SYN_RECV state.
Quoting Jozsef, what it happens if we are out of sync if the
following:
> > b. conntrack entry is outdated, new SYN received
> > - (b1) we ignore it but save the initialization data from it
> > - (b2) when the reply SYN/ACK receives and it matches the saved data,
> > we pick up the new connection
This is what it should happen if we are in SYN_RECV state. Initially,
the SYN packet hits b1, thus we save data from it. But the SYN/ACK
packet is considered a retransmission given that we're in SYN_RECV
state. Therefore, we never hit b2 and we don't get in sync. To fix
this, we ignore SYN/ACK if we are in SYN_RECV. If the previous packet
was a SYN, then we enter the ignore case that get us in sync.
This patch helps a lot to conntrackd in stress scenarios (assumming a
client that generates lots of small TCP connections). During the failover,
consider that the new primary has injected one outdated flow in SYN_RECV
state (this is likely to happen if the conntrack event rate is high
because the backup will be a bit delayed from the primary). With the
current code, if the client starts a new fresh connection that matches
the tuple, the SYN packet will be ignored without updating the state
tracking, and the SYN+ACK in reply will blocked as it will not pass
checkings III or IV (since all state tracking in the original direction
is not initialized because of the SYN packet was ignored and the ignore
case that get us in sync is not applied).
I posted a couple of patches before this one. Changli Gao spotted
a simpler way to fix this problem. This patch implements his idea.
Cc: Changli Gao <xiaosuo@gmail.com>
Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
ct->proto is big(60 bytes) due to structure ip_ct_tcp, and we don't need
to initialize the whole for all the other protocols. This patch moves
proto to the end of structure nf_conn, and pushes the initialization down
to the individual protocols.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
The patch below updates broken web addresses in the kernel
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Finn Thain <fthain@telegraphics.com.au>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Dimitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Mike Frysinger <vapier.adi@gmail.com>
Acked-by: Ben Pfaff <blp@cs.stanford.edu>
Acked-by: Hans J. Koch <hjk@linutronix.de>
Reviewed-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This patch adds the missing bits to support the recovery of TCP flows
without disabling window tracking (aka be_liberal). To ensure a
successful recovery, we have to inject the window scale factor via
ctnetlink.
This patch has been tested with a development snapshot of conntrackd
and the new clause `TCPWindowTracking' that allows to perform strict
TCP window tracking recovery across fail-overs.
With this patch, we don't update the receiver's window until it's not
initiated. We require this to perform a successful recovery. Jozsef
confirmed in a private email that this spotted a real issue since that
should not happen.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
The error handlers might need the template to get the conntrack zone
introduced in the next patches to perform a conntrack lookup.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Split up the IPCT_STATUS event into an IPCT_REPLY event, which is generated
when the IPS_SEEN_REPLY bit is set, and an IPCT_ASSURED event, which is
generated when the IPS_ASSURED bit is set.
In combination with a following patch to support selective event delivery,
this can be used for "sparse" conntrack replication: start replicating the
conntrack entry after it reached the ASSURED state and that way it's SYN-flood
resistant.
Signed-off-by: Patrick McHardy <kaber@trash.net>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1815 commits)
mac80211: fix reorder buffer release
iwmc3200wifi: Enable wimax core through module parameter
iwmc3200wifi: Add wifi-wimax coexistence mode as a module parameter
iwmc3200wifi: Coex table command does not expect a response
iwmc3200wifi: Update wiwi priority table
iwlwifi: driver version track kernel version
iwlwifi: indicate uCode type when fail dump error/event log
iwl3945: remove duplicated event logging code
b43: fix two warnings
ipw2100: fix rebooting hang with driver loaded
cfg80211: indent regulatory messages with spaces
iwmc3200wifi: fix NULL pointer dereference in pmkid update
mac80211: Fix TX status reporting for injected data frames
ath9k: enable 2GHz band only if the device supports it
airo: Fix integer overflow warning
rt2x00: Fix padding bug on L2PAD devices.
WE: Fix set events not propagated
b43legacy: avoid PPC fault during resume
b43: avoid PPC fault during resume
tcp: fix a timewait refcnt race
...
Fix up conflicts due to sysctl cleanups (dead sysctl_check code and
CTL_UNNUMBERED removed) in
kernel/sysctl_check.c
net/ipv4/sysctl_net_ipv4.c
net/ipv6/addrconf.c
net/sctp/sysctl.c
Without this patch, if we receive a SYN packet from the client while
the firewall is out-of-sync, we let it go through. Then, if we see
the SYN/ACK reply coming from the server, we destroy the conntrack
entry and drop the packet to trigger a new retransmission. Then,
the retransmision from the client is used to start a new clean
session.
This patch improves the current handling. Basically, if we see an
unexpected SYN packet, we annotate the TCP options. Then, if we
see the reply SYN/ACK, this means that the firewall was indeed
out-of-sync. Therefore, we set a clean new session from the existing
entry based on the annotated values.
This patch adds two new 8-bits fields that fit in a 16-bits gap of
the ip_ct_tcp structure.
This patch is particularly useful for conntrackd since the
asynchronous nature of the state-synchronization allows to have
backup nodes that are not perfect copies of the master. This helps
to improve the recovery under some worst-case scenarios.
I have tested this by creating lots of conntrack entries in wrong
state:
for ((i=1024;i<65535;i++)); do conntrack -I -p tcp -s 192.168.2.101 -d 192.168.2.2 --sport $i --dport 80 -t 800 --state ESTABLISHED -u ASSURED,SEEN_REPLY; done
Then, I make some TCP connections:
$ echo GET / | nc 192.168.2.2 80
The events show the result:
[UPDATE] tcp 6 60 SYN_RECV src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
[UPDATE] tcp 6 432000 ESTABLISHED src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
[UPDATE] tcp 6 120 FIN_WAIT src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
[UPDATE] tcp 6 30 LAST_ACK src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
[UPDATE] tcp 6 120 TIME_WAIT src=192.168.2.101 dst=192.168.2.2 sport=33220 dport=80 src=192.168.2.2 dst=192.168.2.101 sport=80 dport=33220 [ASSURED]
and tcpdump shows no retransmissions:
20:47:57.271951 IP 192.168.2.101.33221 > 192.168.2.2.www: S 435402517:435402517(0) win 5840 <mss 1460,sackOK,timestamp 4294961827 0,nop,wscale 6>
20:47:57.273538 IP 192.168.2.2.www > 192.168.2.101.33221: S 3509927945:3509927945(0) ack 435402518 win 5792 <mss 1460,sackOK,timestamp 235681024 4294961827,nop,wscale 4>
20:47:57.273608 IP 192.168.2.101.33221 > 192.168.2.2.www: . ack 3509927946 win 92 <nop,nop,timestamp 4294961827 235681024>
20:47:57.273693 IP 192.168.2.101.33221 > 192.168.2.2.www: P 435402518:435402524(6) ack 3509927946 win 92 <nop,nop,timestamp 4294961827 235681024>
20:47:57.275492 IP 192.168.2.2.www > 192.168.2.101.33221: . ack 435402524 win 362 <nop,nop,timestamp 235681024 4294961827>
20:47:57.276492 IP 192.168.2.2.www > 192.168.2.101.33221: P 3509927946:3509928082(136) ack 435402524 win 362 <nop,nop,timestamp 235681025 4294961827>
20:47:57.276515 IP 192.168.2.101.33221 > 192.168.2.2.www: . ack 3509928082 win 108 <nop,nop,timestamp 4294961828 235681025>
20:47:57.276521 IP 192.168.2.2.www > 192.168.2.101.33221: F 3509928082:3509928082(0) ack 435402524 win 362 <nop,nop,timestamp 235681025 4294961827>
20:47:57.277369 IP 192.168.2.101.33221 > 192.168.2.2.www: F 435402524:435402524(0) ack 3509928083 win 108 <nop,nop,timestamp 4294961828 235681025>
20:47:57.279491 IP 192.168.2.2.www > 192.168.2.101.33221: . ack 435402525 win 362 <nop,nop,timestamp 235681025 4294961828>
I also added a rule to log invalid packets, with no occurrences :-) .
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Resolve the conflict between v2.6.32-rc7 where dn_def_dev_handler
gets a small bug fix and the sysctl tree where I am removing all
sysctl strategy routines.
Now that sys_sysctl is a compatiblity wrapper around /proc/sys
all sysctl strategy routines, and all ctl_name and strategy
entries in the sysctl tables are unused, and can be
revmoed.
In addition neigh_sysctl_register has been modified to no longer
take a strategy argument and it's callers have been modified not
to pass one.
Cc: "David Miller" <davem@davemloft.net>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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 a3a9f79e36).
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: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
When NAT helpers change the TCP packet size, the highest seen sequence
number needs to be corrected. This is currently only done upwards, when
the packet size is reduced the sequence number is unchanged. This causes
TCP conntrack to falsely detect unacknowledged data and decrease the
timeout.
Fix by updating the highest seen sequence number in both directions after
packet mangling.
Tested-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: Patrick 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: Patrick 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: Pablo Neira Ayuso <pablo@netfilter.org>
The patch below adds supporting TCP simultaneous open to conntrack. The
unused LISTEN state is replaced by a new state (SYN_SENT2) denoting the
second SYN sent from the reply direction in the new case. The state table
is updated and the function tcp_in_window is modified to handle
simultaneous open.
The functionality can fairly easily be tested by socat. A sample tcpdump
recording
23:21:34.244733 IP (tos 0x0, ttl 64, id 49224, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.254.2020 > 192.168.0.1.2020: S, cksum 0xe75f (correct), 3383710133:3383710133(0) win 5840 <mss 1460,sackOK,timestamp 173445629 0,nop,wscale 7>
23:21:34.244783 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.0.1.2020 > 192.168.0.254.2020: R, cksum 0x0253 (correct), 0:0(0) ack 3383710134 win 0
23:21:36.038680 IP (tos 0x0, ttl 64, id 28092, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.1.2020 > 192.168.0.254.2020: S, cksum 0x704b (correct), 2634546729:2634546729(0) win 5840 <mss 1460,sackOK,timestamp 824213 0,nop,wscale 1>
23:21:36.038777 IP (tos 0x0, ttl 64, id 49225, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.254.2020 > 192.168.0.1.2020: S, cksum 0xb179 (correct), 3383710133:3383710133(0) ack 2634546730 win 5840 <mss 1460,sackOK,timestamp 173447423 824213,nop,wscale 7>
23:21:36.038847 IP (tos 0x0, ttl 64, id 28093, offset 0, flags [DF], proto TCP (6), length 52) 192.168.0.1.2020 > 192.168.0.254.2020: ., cksum 0xebad (correct), ack 3383710134 win 2920 <nop,nop,timestamp 824213 173447423>
and the corresponding netlink events:
[NEW] tcp 6 120 SYN_SENT src=192.168.0.254 dst=192.168.0.1 sport=2020 dport=2020 [UNREPLIED] src=192.168.0.1 dst=192.168.0.254 sport=2020 dport=2020
[UPDATE] tcp 6 120 LISTEN src=192.168.0.254 dst=192.168.0.1 sport=2020 dport=2020 src=192.168.0.1 dst=192.168.0.254 sport=2020 dport=2020
[UPDATE] tcp 6 60 SYN_RECV src=192.168.0.254 dst=192.168.0.1 sport=2020 dport=2020 src=192.168.0.1 dst=192.168.0.254 sport=2020 dport=2020
[UPDATE] tcp 6 432000 ESTABLISHED src=192.168.0.254 dst=192.168.0.1 sport=2020 dport=2020 src=192.168.0.1 dst=192.168.0.254 sport=2020 dport=2020 [ASSURED]
The RST packet was dropped in the raw table, thus it did not reach
conntrack. nfnetlink_conntrack is unpatched so it shows the new SYN_SENT2
state as the old unused LISTEN.
With TCP simultaneous open support we satisfy REQ-2 in RFC 5382 ;-) .
Additional minor correction in this patch is that in order to catch
uninitialized reply directions, "td_maxwin == 0" is used instead of
"td_end == 0" because the former can't be true except in uninitialized
state while td_end may accidentally be equal to zero in the mid of a
connection.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Robert L Mathews discovered that some clients send evil TCP RST segments,
which are accepted by netfilter conntrack but discarded by the
destination. Thus the conntrack entry is destroyed but the destination
retransmits data until timeout.
The same technique, i.e. sending properly crafted RST segments, can easily
be used to bypass connlimit/connbytes based restrictions (the sample
script written by Robert can be found in the netfilter mailing list
archives).
The patch below adds a new flag and new field to struct ip_ct_tcp_state so
that checking RST segments can be made more strict and thus TCP conntrack
can catch the invalid ones: the RST segment is accepted only if its
sequence number higher than or equal to the highest ack we seen from the
other direction. (The last_ack field cannot be reused because it is used
to catch resent packets.)
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This patch fixes an unaligned memory access in tcp_sack while reading
sequence numbers from TCP selective acknowledgement options. Prior to
applying this patch, upstream linux-2.6.27.20 was occasionally
generating messages like this on my sparc64 system:
[54678.532071] Kernel unaligned access at TPC[6b17d4] tcp_packet+0xcd4/0xd00
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Patrick 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: Christoph Paasch <christoph.paasch@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
I want to compile out proc_* and sysctl_* handlers totally and
stub them to NULL depending on config options, however usage of &
will prevent this, since taking adress of NULL pointer will break
compilation.
So, drop & in front of every ->proc_handler and every ->strategy
handler, it was never needed in fact.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is cleaner, we already know conntrack to which event is relevant.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Again, it's deducible from skb, but we're going to use it for
nf_conntrack_checksum and statistics, so just pass it from upper layer.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
and (try to) consistently use u_int8_t for the L3 family.
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
In order to time out dead connections quicker, keep track of outstanding data
and cap the timeout.
Suggested by Herbert Xu.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
When a conntrack entry is destroyed in process context and destruction
is interrupted by packet processing and the packet is an attempt to
reopen a closed connection, TCP conntrack tries to kill the old entry
itself and returns NF_REPEAT to pass the packet through the hook
again. This may lead to an endless loop: TCP conntrack repeatedly
finds the old entry, but can not kill it itself since destruction
is already in progress, but destruction in process context can not
complete since TCP conntrack is keeping the CPU busy.
Drop the packet in TCP conntrack if we can't kill the connection
ourselves to avoid this.
Reported by: hemao77@gmail.com [ Kernel bugzilla #11058 ]
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Lost connections was reported by Thomas Bätzler (running 2.6.25 kernel) on
the netfilter mailing list (see the thread "Weird nat/conntrack Problem
with PASV FTP upload"). He provided tcpdump recordings which helped to
find a long lingering bug in conntrack.
In TCP connection tracking, checking the lower bound of valid ACK could
lead to mark valid packets as INVALID because:
- We have got a "higher or equal" inequality, but the test checked
the "higher" condition only; fixed.
- If the packet contains a SACK option, it could occur that the ACK
value was before the left edge of our (S)ACK "window": if a previous
packet from the other party intersected the right edge of the window
of the receiver, we could move forward the window parameters beyond
accepting a valid ack. Therefore in this patch we check the rightmost
SACK edge instead of the ACK value in the lower bound of valid (S)ACK
test.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently the last packet of a connection isn't accounted when its causing
abnormal termination.
Introduces nf_ct_kill_acct() which increments the accounting counters on
conntrack kill. The new function was necessary, because there are calls
to nf_ct_kill() which don't need accounting:
nf_conntrack_proto_tcp.c line ~847:
Kills ct and returns NF_REPEAT. We don't want to count twice.
nf_conntrack_proto_tcp.c line ~880:
Kills ct and returns NF_DROP. I think we don't want to count dropped
packets.
nf_conntrack_netlink.c line ~824:
As far as I can see ctnetlink_del_conntrack() is used to destroy a
conntrack on behalf of the user. There is an sk_buff, but I don't think
this is an actual packet. Incrementing counters here is therefore not
desired.
Signed-off-by: Fabian Hugelshofer <hugelshofer2006@gmx.ch>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Encapsulate the common
if (del_timer(&ct->timeout))
ct->timeout.function((unsigned long)ct)
sequence in a new function.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Directly call IPv4 and IPv6 variants where the address family is
easily known.
Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Invalid states can cause out-of-bound memory accesses of the state table.
Also don't insist on having a new state contained in the netlink message.
Signed-off-by: Patrick McHardy <kaber@trash.net>
TCP connection tracking in netfilter did not handle TCP reopening
properly: active close was taken into account for one side only and
not for any side, which is fixed now. The patch includes more comments
to explain the logic how the different cases are handled.
The bug was discovered by Jeff Chua.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Constify a few data tables use const qualifiers on variables where
possible in the nf_*_proto_tcp sources.
Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rename all "conntrack" variables to "ct" for more consistency and
avoiding some overly long lines.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Teach sparse about locking here, and fix signed/unsigned warnings.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Instead of keeping pointers to the timeout values in a table, simply
put the timeout values in the table directly.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The TCP and SCTP conntrack state transition tables only holds
small numbers, but gcc uses 4 byte per entry for the enum. Switching
to an u8 reduces the size from 480 to 120 bytes for TCP and from
576 to 144 bytes for SCTP.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The IPv4 and IPv6 hook values are identical, yet some code tries to figure
out the "correct" value by looking at the address family. Introduce NF_INET_*
values for both IPv4 and IPv6. The old values are kept in a #ifndef __KERNEL__
section for userspace compatibility.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
* 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6: (51 commits)
[IPV6]: Fix again the fl6_sock_lookup() fixed locking
[NETFILTER]: nf_conntrack_tcp: fix connection reopening fix
[IPV6]: Fix race in ipv6_flowlabel_opt() when inserting two labels
[IPV6]: Lost locking in fl6_sock_lookup
[IPV6]: Lost locking when inserting a flowlabel in ipv6_fl_list
[NETFILTER]: xt_sctp: fix mistake to pass a pointer where array is required
[NET]: Fix OOPS due to missing check in dev_parse_header().
[TCP]: Remove lost_retrans zero seqno special cases
[NET]: fix carrier-on bug?
[NET]: Fix uninitialised variable in ip_frag_reasm()
[IPSEC]: Rename mode to outer_mode and add inner_mode
[IPSEC]: Disallow combinations of RO and AH/ESP/IPCOMP
[IPSEC]: Use the top IPv4 route's peer instead of the bottom
[IPSEC]: Store afinfo pointer in xfrm_mode
[IPSEC]: Add missing BEET checks
[IPSEC]: Move type and mode map into xfrm_state.c
[IPSEC]: Fix length check in xfrm_parse_spi
[IPSEC]: Move ip_summed zapping out of xfrm6_rcv_spi
[IPSEC]: Get nexthdr from caller in xfrm6_rcv_spi
[IPSEC]: Move tunnel parsing for IPv4 out of xfrm4_input
...
No one has bothered to set strategy routine for the the netfilter sysctls that
return jiffies to be sysctl_jiffies.
So it appears the sys_sysctl path is unused and untested, so this patch
removes the binary sysctl numbers.
Which fixes the netfilter oops in 2.6.23-rc2-mm2 for me.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If one side aborts an established connection, the entry still lingers
for 10s in conntrack for the late packets. Allow to open up the
connection again for the party which sent the RST packet.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Tested-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
With your description I could reproduce the bug and actually you were
completely right: the code above is incorrect. Somehow I was able to
misread RFC1122 and mixed the roles :-(:
When a connection is >>closed actively<<, it MUST linger in
TIME-WAIT state for a time 2xMSL (Maximum Segment Lifetime).
However, it MAY >>accept<< a new SYN from the remote TCP to
reopen the connection directly from TIME-WAIT state, if it:
[...]
The fix is as follows: if the receiver initiated an active close, then the
sender may reopen the connection - otherwise try to figure out if we hold
a dead connection.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Tested-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
There is no struct nfattr anymore, rename functions to 'nlattr'.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Get rid of the duplicated rtnetlink macros and use the generic netlink
attribute functions. The old duplicated stuff is moved to a new header
file that exists just for userspace.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch cleans up duplicate includes in
net/netfilter/
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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>
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>
Jesper Dangaard Brouer