iptables/nftables support responding to tcp packets with tcp resets.
The generated tcp reset packet passes through both output and postrouting
netfilter hooks, but conntrack will never see them because the generated
skb has its ->nfct pointer copied over from the packet that triggered the
reset rule.
If the reset rule is used for established connections, this
may result in the conntrack entry to be around for a very long
time (default timeout is 5 days).
One way to avoid this would be to not copy the nf_conn pointer
so that the rest packet passes through conntrack too.
Problem is that output rules might not have the same conntrack
zone setup as the prerouting ones, so its possible that the
reset skb won't find the correct entry. Generating a template
entry for the skb seems error prone as well.
Add an explicit "closing" function that switches a confirmed
conntrack entry to closed state and wire this up for tcp.
If the entry isn't confirmed, no action is needed because
the conntrack entry will never be committed to the table.
Reported-by: Russel King <linux@armlinux.org.uk>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Those are all useless or dubious.
getorigdst() is called via setsockopt, so return value/errno will
already indicate an appropriate error.
For other pr_debug calls there are better replacements, such as
slab/slub debugging or 'conntrack -E' (ctnetlink events).
Signed-off-by: Florian Westphal <fw@strlen.de>
When a connection is re-used, following can happen:
[ connection starts to close, fin sent in either direction ]
> syn # initator quickly reuses connection
< ack # peer sends a challenge ack
> rst # rst, sequence number == ack_seq of previous challenge ack
> syn # this syn is expected to pass
Problem is that the rst will fail window validation, so it gets
tagged as invalid.
If ruleset drops such packets, we get repeated syn-retransmits until
initator gives up or peer starts responding with syn/ack.
Before the commit indicated in the "Fixes" tag below this used to work:
The challenge-ack made conntrack re-init state based on the challenge
ack itself, so the following rst would pass window validation.
Add challenge-ack support: If we get ack for syn, record the ack_seq,
and then check if the rst sequence number matches the last ack number
seen in reverse direction.
Fixes: c7aab4f170 ("netfilter: nf_conntrack_tcp: re-init for syn packets only")
Reported-by: Michal Tesar <mtesar@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
In case the endpoints and conntrack go out-of-sync, i.e. there is
disagreement wrt. validy of sequence/ack numbers between conntracks
internal state and those of the endpoints, connections can hang for a
long time (until ESTABLISHED timeout).
This adds a check to detect a fin/fin exchange even if those are
invalid. The timeout is then lowered to UNACKED (default 300s).
Signed-off-by: Florian Westphal <fw@strlen.de>
After previous patch, the conditional branch is obsolete, reformat it.
gcc generates same code as before this change.
Signed-off-by: Florian Westphal <fw@strlen.de>
If 'nf_conntrack_tcp_loose' is off (the default), tcp packets that are
outside of the current window are marked as INVALID.
nf/iptables rulesets often drop such packets via 'ct state invalid' or
similar checks.
For overly delayed acks, this can be a nuisance if such 'invalid' packets
are also logged.
Since they are not invalid in a strict sense, just ignore them, i.e.
conntrack won't extend timeout or change state so that they do not match
invalid state rules anymore.
This also avoids unwantend connection stalls in case conntrack considers
retransmission (of data that did not reach the peer) as too old.
The else branch of the conditional becomes obsolete.
Next patch will reformant the now always-true if condition.
The existing workaround for data that exceeds the calculated receive
window is adjusted to use the 'ignore' state so that these packets do
not refresh the timeout or change state other than updating ->td_end.
Signed-off-by: Florian Westphal <fw@strlen.de>
tcp_in_window returns true if the packet is in window and false if it is
not.
If its outside of window, packet will be treated as INVALID.
There are corner cases where the packet should still be tracked, because
rulesets may drop or log such packets, even though they can occur during
normal operation, such as overly delayed acks.
In extreme cases, connection may hang forever because conntrack state
differs from real state.
There is no retransmission for ACKs.
In case of ACK loss after conntrack processing, its possible that a
connection can be stuck because the actual retransmits are considered
stale ("SEQ is under the lower bound (already ACKed data
retransmitted)".
The problem is made worse by carrier-grade-nat which can also result
in stale packets from old connections to get treated as 'recent' packets
in conntrack (it doesn't support tcp timestamps at this time).
Prepare tcp_in_window() to return an enum that tells the desired
action (in-window/accept, bogus/drop).
A third action (accept the packet as in-window, but do not change
state) is added in a followup patch.
Signed-off-by: Florian Westphal <fw@strlen.de>
When a TCP sends more bytes than allowed by the receive window, all future
packets can be marked as invalid.
This can clog up the conntrack table because of 5-day default timeout.
Sequence of packets:
01 initiator > responder: [S], seq 171, win 5840, options [mss 1330,sackOK,TS val 63 ecr 0,nop,wscale 1]
02 responder > initiator: [S.], seq 33211, ack 172, win 65535, options [mss 1460,sackOK,TS val 010 ecr 63,nop,wscale 8]
03 initiator > responder: [.], ack 33212, win 2920, options [nop,nop,TS val 068 ecr 010], length 0
04 initiator > responder: [P.], seq 172:240, ack 33212, win 2920, options [nop,nop,TS val 279 ecr 010], length 68
Window is 5840 starting from 33212 -> 39052.
05 responder > initiator: [.], ack 240, win 256, options [nop,nop,TS val 872 ecr 279], length 0
06 responder > initiator: [.], seq 33212:34530, ack 240, win 256, options [nop,nop,TS val 892 ecr 279], length 1318
This is fine, conntrack will flag the connection as having outstanding
data (UNACKED), which lowers the conntrack timeout to 300s.
07 responder > initiator: [.], seq 34530:35848, ack 240, win 256, options [nop,nop,TS val 892 ecr 279], length 1318
08 responder > initiator: [.], seq 35848:37166, ack 240, win 256, options [nop,nop,TS val 892 ecr 279], length 1318
09 responder > initiator: [.], seq 37166:38484, ack 240, win 256, options [nop,nop,TS val 892 ecr 279], length 1318
10 responder > initiator: [.], seq 38484:39802, ack 240, win 256, options [nop,nop,TS val 892 ecr 279], length 1318
Packet 10 is already sending more than permitted, but conntrack doesn't
validate this (only seq is tested vs. maxend, not 'seq+len').
38484 is acceptable, but only up to 39052, so this packet should
not have been sent (or only 568 bytes, not 1318).
At this point, connection is still in '300s' mode.
Next packet however will get flagged:
11 responder > initiator: [P.], seq 39802:40128, ack 240, win 256, options [nop,nop,TS val 892 ecr 279], length 326
nf_ct_proto_6: SEQ is over the upper bound (over the window of the receiver) .. LEN=378 .. SEQ=39802 ACK=240 ACK PSH ..
Now, a couple of replies/acks comes in:
12 initiator > responder: [.], ack 34530, win 4368,
[.. irrelevant acks removed ]
16 initiator > responder: [.], ack 39802, win 8712, options [nop,nop,TS val 296201291 ecr 2982371892], length 0
This ack is significant -- this acks the last packet send by the
responder that conntrack considered valid.
This means that ack == td_end. This will withdraw the
'unacked data' flag, the connection moves back to the 5-day timeout
of established conntracks.
17 initiator > responder: ack 40128, win 10030, ...
This packet is also flagged as invalid.
Because conntrack only updates state based on packets that are
considered valid, packet 11 'did not exist' and that gets us:
nf_ct_proto_6: ACK is over upper bound 39803 (ACKed data not seen yet) .. SEQ=240 ACK=40128 WINDOW=10030 RES=0x00 ACK URG
Because this received and processed by the endpoints, the conntrack entry
remains in a bad state, no packets will ever be considered valid again:
30 responder > initiator: [F.], seq 40432, ack 2045, win 391, ..
31 initiator > responder: [.], ack 40433, win 11348, ..
32 initiator > responder: [F.], seq 2045, ack 40433, win 11348 ..
... all trigger 'ACK is over bound' test and we end up with
non-early-evictable 5-day default timeout.
NB: This patch triggers a bunch of checkpatch warnings because of silly
indent. I will resend the cleanup series linked below to reduce the
indent level once this change has propagated to net-next.
I could route the cleanup via nf but that causes extra backport work for
stable maintainers.
Link: https://lore.kernel.org/netfilter-devel/20220720175228.17880-1-fw@strlen.de/T/#mb1d7147d36294573cc4f81d00f9f8dadfdd06cd8
Signed-off-by: Florian Westphal <fw@strlen.de>
They are either obsolete or useless.
Those in the normal processing path cannot be enabled on a production
system; they generate too much noise.
One pr_debug call resides in an error path and does provide useful info,
merge it with the existing nf_log_invalid().
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Jaco Kroon reported tcp problems that Eric Dumazet and Neal Cardwell
pinpointed to nf_conntrack tcp_in_window() bug.
tcp trace shows following sequence:
I > R Flags [S], seq 3451342529, win 62580, options [.. tfo [|tcp]>
R > I Flags [S.], seq 2699962254, ack 3451342530, win 65535, options [..]
R > I Flags [P.], seq 1:89, ack 1, [..]
Note 3rd ACK is from responder to initiator so following branch is taken:
} else if (((state->state == TCP_CONNTRACK_SYN_SENT
&& dir == IP_CT_DIR_ORIGINAL)
|| (state->state == TCP_CONNTRACK_SYN_RECV
&& dir == IP_CT_DIR_REPLY))
&& after(end, sender->td_end)) {
... because state == TCP_CONNTRACK_SYN_RECV and dir is REPLY.
This causes the scaling factor to be reset to 0: window scale option
is only present in syn(ack) packets. This in turn makes nf_conntrack
mark valid packets as out-of-window.
This was always broken, it exists even in original commit where
window tracking was added to ip_conntrack (nf_conntrack predecessor)
in 2.6.9-rc1 kernel.
Restrict to 'tcph->syn', just like the 3rd condtional added in
commit 82b72cb946 ("netfilter: conntrack: re-init state for retransmitted syn-ack").
Upon closer look, those conditionals/branches can be merged:
Because earlier checks prevent syn-ack from showing up in
original direction, the 'dir' checks in the conditional quoted above are
redundant, remove them. Return early for pure syn retransmitted in reply
direction (simultaneous open).
Fixes: 9fb9cbb108 ("[NETFILTER]: Add nf_conntrack subsystem.")
Reported-by: Jaco Kroon <jaco@uls.co.za>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Do not reset IP_CT_TCP_FLAG_BE_LIBERAL flag in out-of-sync scenarios
coming before the TCP window tracking, otherwise such connections will
fail in the window check.
Update tcp_options() to leave this flag in place and add a new helper
function to reset the tcp window state.
Based on patch from Sven Auhagen.
Fixes: c4832c7bbc ("netfilter: nf_ct_tcp: improve out-of-sync situation in TCP tracking")
Tested-by: Sven Auhagen <sven.auhagen@voleatech.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
TCP conntrack assumes that a syn-ack retransmit is identical to the
previous syn-ack. This isn't correct and causes stuck 3whs in some more
esoteric scenarios. tcpdump to illustrate the problem:
client > server: Flags [S] seq 1365731894, win 29200, [mss 1460,sackOK,TS val 2083035583 ecr 0,wscale 7]
server > client: Flags [S.] seq 145824453, ack 643160523, win 65535, [mss 8952,wscale 5,TS val 3215367629 ecr 2082921663]
Note the invalid/outdated synack ack number.
Conntrack marks this syn-ack as out-of-window/invalid, but it did
initialize the reply direction parameters based on this packets content.
client > server: Flags [S] seq 1365731894, win 29200, [mss 1460,sackOK,TS val 2083036623 ecr 0,wscale 7]
... retransmit...
server > client: Flags [S.], seq 145824453, ack 643160523, win 65535, [mss 8952,wscale 5,TS val 3215368644 ecr 2082921663]
and another bogus synack. This repeats, then client re-uses for a new
attempt:
client > server: Flags [S], seq 2375731741, win 29200, [mss 1460,sackOK,TS val 2083100223 ecr 0,wscale 7]
server > client: Flags [S.], seq 145824453, ack 643160523, win 65535, [mss 8952,wscale 5,TS val 3215430754 ecr 2082921663]
... but still gets a invalid syn-ack.
This repeats until:
server > client: Flags [S.], seq 145824453, ack 643160523, win 65535, [mss 8952,wscale 5,TS val 3215437785 ecr 2082921663]
server > client: Flags [R.], seq 145824454, ack 643160523, win 65535, [mss 8952,wscale 5,TS val 3215443451 ecr 2082921663]
client > server: Flags [S], seq 2375731741, win 29200, [mss 1460,sackOK,TS val 2083115583 ecr 0,wscale 7]
server > client: Flags [S.], seq 162602410, ack 2375731742, win 65535, [mss 8952,wscale 5,TS val 3215445754 ecr 2083115583]
This syn-ack has the correct ack number, but conntrack flags it as
invalid: The internal state was created from the first syn-ack seen
so the sequence number of the syn-ack is treated as being outside of
the announced window.
Don't assume that retransmitted syn-ack is identical to previous one.
Treat it like the first syn-ack and reinit state.
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
It seems more readable to use a common helper in the followup fix rather
than copypaste or goto.
No functional change intended. The function is only called for syn-ack
or syn in repy direction in case of simultaneous open.
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
These two sysctls were added because the hardcoded defaults (2 minutes,
tcp, 30 seconds, udp) turned out to be too low for some setups.
They appeared in 5.14-rc1 so it should be fine to remove it again.
Marcelo convinced me that there should be no difference between a flow
that was offloaded vs. a flow that was not wrt. timeout handling.
Thus the default is changed to those for TCP established and UDP stream,
5 days and 120 seconds, respectively.
Marcelo also suggested to account for the timeout value used for the
offloading, this avoids increase beyond the value in the conntrack-sysctl
and will also instantly expire the conntrack entry with altered sysctls.
Example:
nf_conntrack_udp_timeout_stream=60
nf_flowtable_udp_timeout=60
This will remove offloaded udp flows after one minute, rather than two.
An earlier version of this patch also cleared the ASSURED bit to
allow nf_conntrack to evict the entry via early_drop (i.e., table full).
However, it looks like we can safely assume that connection timed out
via HW is still in established state, so this isn't needed.
Quoting Oz:
[..] the hardware sends all packets with a set FIN flags to sw.
[..] Connections that are aged in hardware are expected to be in the
established state.
In case it turns out that back-to-sw-path transition can occur for
'dodgy' connections too (e.g., one side disappeared while software-path
would have been in RETRANS timeout), we can adjust this later.
Cc: Oz Shlomo <ozsh@nvidia.com>
Cc: Paul Blakey <paulb@nvidia.com>
Suggested-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This patch adds a new sysctl tcp_ignore_invalid_rst to disable marking
out of segments RSTs as INVALID.
Signed-off-by: Ali Abdallah <aabdallah@suse.de>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
If we receive a SYN packet in original direction on an existing
connection tracking entry, we let this SYN through because conntrack
might be out-of-sync.
Conntrack gets back in sync when server responds with SYN/ACK and state
gets updated accordingly.
However, if server replies with RST, this packet might be marked as
INVALID because td_maxack value reflects the *old* conntrack state
and not the state of the originator of the RST.
Avoid td_maxack-based checks if previous packet was a SYN.
Unfortunately that is not be enough: an out of order ACK in original
direction updates last_index, so we still end up marking valid RST.
Thus disable the sequence check when we are not in established state and
the received RST has a sequence of 0.
Because marking RSTs as invalid usually leads to unwanted timeouts,
also skip RST sequence checks if a conntrack entry is already closing.
Such entries can already be evicted via GC in case the table is full.
Co-developed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Ali Abdallah <aabdallah@suse.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Consider:
client -----> conntrack ---> Host
client sends a SYN, but $Host is unreachable/silent.
Client eventually gives up and the conntrack entry will time out.
However, if the client is restarted with same addr/port pair, it
may prevent the conntrack entry from timing out.
This is noticeable when the existing conntrack entry has no NAT
transformation or an outdated one and port reuse happens either
on client or due to a NAT middlebox.
This change prevents refresh of the timeout for SYN retransmits,
so entry is going away after nf_conntrack_tcp_timeout_syn_sent
seconds (default: 60).
Entry will be re-created on next connection attempt, but then
nat rules will be evaluated again.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
The packet logger backend is unable to provide the incoming (or
outgoing) interface name because that information isn't available.
Pass the hook state, it contains the network namespace, the protocol
family, the network interfaces and other things.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
TCP connections may be offloaded from nf conntrack to nf flow table.
Offloaded connections are aged after 30 seconds of inactivity.
Once aged, ownership is returned to conntrack with a hard coded pickup
time of 120 seconds, after which the connection may be deleted.
eted. The current aging intervals may be too aggressive for some users.
Provide users with the ability to control the nf flow table offload
aging and pickup time intervals via sysctl parameter as a pre-step for
configuring the nf flow table GC timeout intervals.
Signed-off-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Paul Blakey <paulb@nvidia.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Several conntrack helpers and the TCP tracker assume that
skb_header_pointer() never fails based on upfront header validation.
Even if this should not ever happen, BUG_ON() is a too drastic measure,
remove them.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
log_invalid sysctl allows values of 0 to 255 inclusive so we no longer
need a range check: the min/max values can be removed.
This also removes all member variables that were moved to net_generic
data in previous patches.
This reduces size of netns_ct struct by one cache line.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
The packet is not flagged as invalid: conntrack will accept it and
its associated with the conntrack entry.
This happens e.g. when receiving a retransmitted SYN in SYN_RECV state.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
DESTROY events do not include the remaining timeout.
Add the timeout if the entry was removed explicitly. This can happen
when a conntrack gets deleted prematurely, e.g. due to a tcp reset,
module removal, netdev notifier (nat/masquerade device went down),
ctnetlink and so on.
Add the protocol state too for the destroy message to check for abnormal
state on connection termination.
Joint work with Pablo.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
There is no easy way to distinguish if a conntracked tcp packet is
marked invalid because of tcp_in_window() check error or because
it doesn't belong to an existing connection. With this patch,
openvswitch sets liberal tcp flag for the established sessions so
that out of window packets are not marked invalid.
A helper function - nf_ct_set_tcp_be_liberal(nf_conn) is added which
sets this flag for both the directions of the nf_conn.
Suggested-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Numan Siddique <nusiddiq@redhat.com>
Acked-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/20201116130126.3065077-1-nusiddiq@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
If the first packet conntrack sees after a re-register is an outgoing
keepalive packet with no data (SEG.SEQ = SND.NXT-1), td_end is set to
SND.NXT-1.
When the peer correctly acknowledges SND.NXT, tcp_in_window fails
check III (Upper bound for valid (s)ack: sack <= receiver.td_end) and
returns false, which cascades into nf_conntrack_in setting
skb->_nfct = 0 and in later conntrack iptables rules not matching.
In cases where iptables are dropping packets that do not match
conntrack rules this can result in idle tcp connections to time out.
v2: adjust td_end when getting the reply rather than when sending out
the keepalive packet.
Fixes: f94e63801a ("netfilter: conntrack: reset tcp maxwin on re-register")
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Drop duplicated words in net/netfilter/ and net/ipv4/netfilter/.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Jakub Jankowski reported following oddity:
After 3 way handshake completes, timeout of new connection is set to
max_retrans (300s) instead of established (5 days).
shortened excerpt from pcap provided:
25.070622 IP (flags [DF], proto TCP (6), length 52)
10.8.5.4.1025 > 10.8.1.2.80: Flags [S], seq 11, win 64240, [wscale 8]
26.070462 IP (flags [DF], proto TCP (6), length 48)
10.8.1.2.80 > 10.8.5.4.1025: Flags [S.], seq 82, ack 12, win 65535, [wscale 3]
27.070449 IP (flags [DF], proto TCP (6), length 40)
10.8.5.4.1025 > 10.8.1.2.80: Flags [.], ack 83, win 512, length 0
Turns out the last_win is of u16 type, but we store the scaled value:
512 << 8 (== 0x20000) becomes 0 window.
The Fixes tag is not correct, as the bug has existed forever, but
without that change all that this causes might cause is to mistake a
window update (to-nonzero-from-zero) for a retransmit.
Fixes: fbcd253d24 ("netfilter: conntrack: lower timeout to RETRANS seconds if window is 0")
Reported-by: Jakub Jankowski <shasta@toxcorp.com>
Tested-by: Jakub Jankowski <shasta@toxcorp.com>
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>
Resolve conflict between d2912cb15b ("treewide: Replace GPLv2
boilerplate/reference with SPDX - rule 500") removing the GPL disclaimer
and fe03d47456 ("Update my email address") which updates Jozsef
Kadlecsik's email.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It's better to use my kadlec@netfilter.org email address in
the source code. I might not be able to use
kadlec@blackhole.kfki.hu in the future.
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
We currently have two levels of strict validation:
1) liberal (default)
- undefined (type >= max) & NLA_UNSPEC attributes accepted
- attribute length >= expected accepted
- garbage at end of message accepted
2) strict (opt-in)
- NLA_UNSPEC attributes accepted
- attribute length >= expected accepted
Split out parsing strictness into four different options:
* TRAILING - check that there's no trailing data after parsing
attributes (in message or nested)
* MAXTYPE - reject attrs > max known type
* UNSPEC - reject attributes with NLA_UNSPEC policy entries
* STRICT_ATTRS - strictly validate attribute size
The default for future things should be *everything*.
The current *_strict() is a combination of TRAILING and MAXTYPE,
and is renamed to _deprecated_strict().
The current regular parsing has none of this, and is renamed to
*_parse_deprecated().
Additionally it allows us to selectively set one of the new flags
even on old policies. Notably, the UNSPEC flag could be useful in
this case, since it can be arranged (by filling in the policy) to
not be an incompatible userspace ABI change, but would then going
forward prevent forgetting attribute entries. Similar can apply
to the POLICY flag.
We end up with the following renames:
* nla_parse -> nla_parse_deprecated
* nla_parse_strict -> nla_parse_deprecated_strict
* nlmsg_parse -> nlmsg_parse_deprecated
* nlmsg_parse_strict -> nlmsg_parse_deprecated_strict
* nla_parse_nested -> nla_parse_nested_deprecated
* nla_validate_nested -> nla_validate_nested_deprecated
Using spatch, of course:
@@
expression TB, MAX, HEAD, LEN, POL, EXT;
@@
-nla_parse(TB, MAX, HEAD, LEN, POL, EXT)
+nla_parse_deprecated(TB, MAX, HEAD, LEN, POL, EXT)
@@
expression NLH, HDRLEN, TB, MAX, POL, EXT;
@@
-nlmsg_parse(NLH, HDRLEN, TB, MAX, POL, EXT)
+nlmsg_parse_deprecated(NLH, HDRLEN, TB, MAX, POL, EXT)
@@
expression NLH, HDRLEN, TB, MAX, POL, EXT;
@@
-nlmsg_parse_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
+nlmsg_parse_deprecated_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
@@
expression TB, MAX, NLA, POL, EXT;
@@
-nla_parse_nested(TB, MAX, NLA, POL, EXT)
+nla_parse_nested_deprecated(TB, MAX, NLA, POL, EXT)
@@
expression START, MAX, POL, EXT;
@@
-nla_validate_nested(START, MAX, POL, EXT)
+nla_validate_nested_deprecated(START, MAX, POL, EXT)
@@
expression NLH, HDRLEN, MAX, POL, EXT;
@@
-nlmsg_validate(NLH, HDRLEN, MAX, POL, EXT)
+nlmsg_validate_deprecated(NLH, HDRLEN, MAX, POL, EXT)
For this patch, don't actually add the strict, non-renamed versions
yet so that it breaks compile if I get it wrong.
Also, while at it, make nla_validate and nla_parse go down to a
common __nla_validate_parse() function to avoid code duplication.
Ultimately, this allows us to have very strict validation for every
new caller of nla_parse()/nlmsg_parse() etc as re-introduced in the
next patch, while existing things will continue to work as is.
In effect then, this adds fully strict validation for any new command.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Even if the NLA_F_NESTED flag was introduced more than 11 years ago, most
netlink based interfaces (including recently added ones) are still not
setting it in kernel generated messages. Without the flag, message parsers
not aware of attribute semantics (e.g. wireshark dissector or libmnl's
mnl_nlmsg_fprintf()) cannot recognize nested attributes and won't display
the structure of their contents.
Unfortunately we cannot just add the flag everywhere as there may be
userspace applications which check nlattr::nla_type directly rather than
through a helper masking out the flags. Therefore the patch renames
nla_nest_start() to nla_nest_start_noflag() and introduces nla_nest_start()
as a wrapper adding NLA_F_NESTED. The calls which add NLA_F_NESTED manually
are rewritten to use nla_nest_start().
Except for changes in include/net/netlink.h, the patch was generated using
this semantic patch:
@@ expression E1, E2; @@
-nla_nest_start(E1, E2)
+nla_nest_start_noflag(E1, E2)
@@ expression E1, E2; @@
-nla_nest_start_noflag(E1, E2 | NLA_F_NESTED)
+nla_nest_start(E1, E2)
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
TCP resets cause instant transition from established to closed state
provided the reset is in-window. Endpoints that implement RFC 5961
require resets to match the next expected sequence number.
RST segments that are in-window (but that do not match RCV.NXT) are
ignored, and a "challenge ACK" is sent back.
Main problem for conntrack is that its a middlebox, i.e. whereas an end
host might have ACK'd SEQ (and would thus accept an RST with this
sequence number), conntrack might not have seen this ACK (yet).
Therefore we can't simply flag RSTs with non-exact match as invalid.
This updates RST processing as follows:
1. If the connection is in a state other than ESTABLISHED, nothing is
changed, RST is subject to normal in-window check.
2. If the RSTs sequence number either matches exactly RCV.NXT,
connection state moves to CLOSE.
3. The same applies if the RST sequence number aligns with a previous
packet in the same direction.
In all other cases, the connection remains in ESTABLISHED state.
If the normal-in-window check passes, the timeout will be lowered
to that of CLOSE.
If the peer sends a challenge ack, connection timeout will be reset.
If the challenge ACK triggers another RST (RST was valid after all),
this 2nd RST will match expected sequence and conntrack state changes to
CLOSE.
If no challenge ACK is received, the connection will time out after
CLOSE seconds (10 seconds by default), just like without this patch.
Packetdrill test case:
0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
0.000 bind(3, ..., ...) = 0
0.000 listen(3, 1) = 0
0.100 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7>
0.100 > S. 0:0(0) ack 1 win 64240 <mss 1460,nop,nop,sackOK,nop,wscale 7>
0.200 < . 1:1(0) ack 1 win 257
0.200 accept(3, ..., ...) = 4
// Receive a segment.
0.210 < P. 1:1001(1000) ack 1 win 46
0.210 > . 1:1(0) ack 1001
// Application writes 1000 bytes.
0.250 write(4, ..., 1000) = 1000
0.250 > P. 1:1001(1000) ack 1001
// First reset, old sequence. Conntrack (correctly) considers this
// invalid due to failed window validation (regardless of this patch).
0.260 < R 2:2(0) ack 1001 win 260
// 2nd reset, but too far ahead sequence. Same: correctly handled
// as invalid.
0.270 < R 99990001:99990001(0) ack 1001 win 260
// in-window, but not exact sequence.
// Current Linux kernels might reply with a challenge ack, and do not
// remove connection.
// Without this patch, conntrack state moves to CLOSE.
// With patch, timeout is lowered like CLOSE, but connection stays
// in ESTABLISHED state.
0.280 < R 1010:1010(0) ack 1001 win 260
// Expect challenge ACK
0.281 > . 1001:1001(0) ack 1001 win 501
// With or without this patch, RST will cause connection
// to move to CLOSE (sequence number matches)
// 0.282 < R 1001:1001(0) ack 1001 win 260
// ACK
0.300 < . 1001:1001(0) ack 1001 win 257
// more data could be exchanged here, connection
// is still established
// Client closes the connection.
0.610 < F. 1001:1001(0) ack 1001 win 260
0.650 > . 1001:1001(0) ack 1002
// Close the connection without reading outstanding data
0.700 close(4) = 0
// so one more reset. Will be deemed acceptable with patch as well:
// connection is already closing.
0.701 > R. 1001:1001(0) ack 1002 win 501
// End packetdrill test case.
With patch, this generates following conntrack events:
[NEW] 120 SYN_SENT src=10.0.2.1 dst=10.0.0.1 sport=5437 dport=80 [UNREPLIED]
[UPDATE] 60 SYN_RECV src=10.0.2.1 dst=10.0.0.1 sport=5437 dport=80
[UPDATE] 432000 ESTABLISHED src=10.0.2.1 dst=10.0.0.1 sport=5437 dport=80 [ASSURED]
[UPDATE] 120 FIN_WAIT src=10.0.2.1 dst=10.0.0.1 sport=5437 dport=80 [ASSURED]
[UPDATE] 60 CLOSE_WAIT src=10.0.2.1 dst=10.0.0.1 sport=5437 dport=80 [ASSURED]
[UPDATE] 10 CLOSE src=10.0.2.1 dst=10.0.0.1 sport=5437 dport=80 [ASSURED]
Without patch, first RST moves connection to close, whereas socket state
does not change until FIN is received.
[NEW] 120 SYN_SENT src=10.0.2.1 dst=10.0.0.1 sport=5141 dport=80 [UNREPLIED]
[UPDATE] 60 SYN_RECV src=10.0.2.1 dst=10.0.0.1 sport=5141 dport=80
[UPDATE] 432000 ESTABLISHED src=10.0.2.1 dst=10.0.0.1 sport=5141 dport=80 [ASSURED]
[UPDATE] 10 CLOSE src=10.0.2.1 dst=10.0.0.1 sport=5141 dport=80 [ASSURED]
Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Those were needed we still had modular trackers.
As we don't have those anymore, prefer direct calls and remove all
the (un)register infrastructure associated with this.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Due to historical reasons, all l4 trackers register their own
sysctls.
This leads to copy&pasted boilerplate code, that does exactly same
thing, just with different data structure.
Place all of this in a single file.
This allows to remove the various ctl_table pointers from the ct_netns
structure and reduces overall code size.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
The l4 protocol trackers are invoked via indirect call: l4proto->packet().
With one exception (gre), all l4trackers are builtin, so we can make
.packet optional and use a direct call for most protocols.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Pablo Neira Ayuso says:
====================
Netfilter updates for net-next
The following patchset contains Netfilter updates for your net-next tree:
1) Support for matching on ipsec policy already set in the route, from
Florian Westphal.
2) Split set destruction into deactivate and destroy phase to make it
fit better into the transaction infrastructure, also from Florian.
This includes a patch to warn on imbalance when setting the new
activate and deactivate interfaces.
3) Release transaction list from the workqueue to remove expensive
synchronize_rcu() from configuration plane path. This speeds up
configuration plane quite a bit. From Florian Westphal.
4) Add new xfrm/ipsec extension, this new extension allows you to match
for ipsec tunnel keys such as source and destination address, spi and
reqid. From Máté Eckl and Florian Westphal.
5) Add secmark support, this includes connsecmark too, patches
from Christian Gottsche.
6) Allow to specify remaining bytes in xt_quota, from Chenbo Feng.
One follow up patch to calm a clang warning for this one, from
Nathan Chancellor.
7) Flush conntrack entries based on layer 3 family, from Kristian Evensen.
8) New revision for cgroups2 to shrink the path field.
9) Get rid of obsolete need_conntrack(), as a result from recent
demodularization works.
10) Use WARN_ON instead of BUG_ON, from Florian Westphal.
11) Unused exported symbol in nf_nat_ipv4_fn(), from Florian.
12) Remove superfluous check for timeout netlink parser and dump
functions in layer 4 conntrack helpers.
13) Unnecessary redundant rcu read side locks in NAT redirect,
from Taehee Yoo.
14) Pass nf_hook_state structure to error handlers, patch from
Florian Westphal.
15) Remove ->new() interface from layer 4 protocol trackers. Place
them in the ->packet() interface. From Florian.
16) Place conntrack ->error() handling in the ->packet() interface.
Patches from Florian Westphal.
17) Remove unused parameter in the pernet initialization path,
also from Florian.
18) Remove additional parameter to specify layer 3 protocol when
looking up for protocol tracker. From Florian.
19) Shrink array of layer 4 protocol trackers, from Florian.
20) Check for linear skb only once from the ALG NAT mangling
codebase, from Taehee Yoo.
21) Use rhashtable_walk_enter() instead of deprecated
rhashtable_walk_init(), also from Taehee.
22) No need to flush all conntracks when only one single address
is gone, from Tan Hu.
23) Remove redundant check for NAT flags in flowtable code, from
Taehee Yoo.
24) Use rhashtable_lookup() instead of rhashtable_lookup_fast()
from netfilter codebase, since rcu read lock side is already
assumed in this path.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
sizeof(sizeof()) is quite strange and does not seem to be what
is wanted here.
The issue is detected with the help of Coccinelle.
Fixes: 3921584674 ("netfilter: conntrack: remove nlattr_size pointer from l4proto trackers")
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
l4 protocols are demuxed by l3num, l4num pair.
However, almost all l4 trackers are l3 agnostic.
Only exceptions are:
- gre, icmp (ipv4 only)
- icmpv6 (ipv6 only)
This commit gets rid of the l3 mapping, l4 trackers can now be looked up
by their IPPROTO_XXX value alone, which gets rid of the additional l3
indirection.
For icmp, ipcmp6 and gre, add a check on state->pf and
return -NF_ACCEPT in case we're asked to track e.g. icmpv6-in-ipv4,
this seems more fitting than using the generic tracker.
Additionally we can kill the 2nd l4proto definitions that were needed
for v4/v6 split -- they are now the same so we can use single l4proto
struct for each protocol, rather than two.
The EXPORT_SYMBOLs can be removed as all these object files are
part of nf_conntrack with no external references.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Its unused, next patch will remove l4proto->l3proto number to simplify
l4 protocol demuxer lookup.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
The error() handler gets called before allocating or looking up a
connection tracking entry.
We can instead use direct calls from the ->packet() handlers which get
invoked for every packet anyway.
Only exceptions are icmp and icmpv6, these two special cases will be
handled in the next patch.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Only two protocols need the ->error() function: icmp and icmpv6.
This is because icmp error mssages might be RELATED to an existing
connection (e.g. PMTUD, port unreachable and the like), and their
->error() handlers do this.
The error callback is already optional, so remove it for
udp and call them from ->packet() instead.
As the error() callback can call checksum functions that write to
skb->csum*, the const qualifier has to be removed as well.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
->new() gets invoked after ->error() and before ->packet() if
a conntrack lookup has found no result for the tuple.
We can fold it into ->packet() -- the packet() implementations
can check if the conntrack is confirmed (new) or not
(already in hash).
If its unconfirmed, the conntrack isn't in the hash yet so current
skb created a new conntrack entry.
Only relevant side effect -- if packet() doesn't return NF_ACCEPT
but -NF_ACCEPT (or drop), while the conntrack was just created,
then the newly allocated conntrack is freed right away, rather than not
created in the first place.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
nf_hook_state contains all the hook meta-information: netns, protocol family,
hook location, and so on.
Instead of only passing selected information, pass a pointer to entire
structure.
This will allow to merge the error and the packet handlers and remove
the ->new() function in followup patches.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Now that cttimeout support for nft_ct is in place, these should depend
on CONFIG_NF_CONNTRACK_TIMEOUT otherwise we can crash when dumping the
policy if this option is not enabled.
[ 71.600121] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[...]
[ 71.600141] CPU: 3 PID: 7612 Comm: nft Not tainted 4.18.0+ #246
[...]
[ 71.600188] Call Trace:
[ 71.600201] ? nft_ct_timeout_obj_dump+0xc6/0xf0 [nft_ct]
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
tcp, sctp and dccp trackers re-use the userspace ctnetlink states
to index their timeout arrays, which means timeout[0] is never
used. Copy the 'new' state (syn-sent, dccp-request, ..) to 0 as well
so external users can simply read it off timeouts[0] without need to
differentiate dccp/sctp/tcp and udp/icmp/gre/generic.
The alternative is to map all array accesses to 'i - 1', but that
is a much more intrusive change.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Florian Westphal