linux.git/net/netfilter, branch v5.1

netfilter: fix nf_l4proto_log_invalid to log invalid packets

2019-04-22T08:38:50+00:00

It doesn't log a packet if sysctl_log_invalid isn't equal to protonum
OR sysctl_log_invalid isn't equal to IPPROTO_RAW. This sentence is
always true. I believe we need to replace OR to AND.

Cc: Florian Westphal 
Fixes: c4f3db1595827 ("netfilter: conntrack: add and use nf_l4proto_log_invalid")
Signed-off-by: Andrei Vagin 
Acked-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: never get/set skb->tstamp

2019-04-22T08:34:30+00:00

setting net.netfilter.nf_conntrack_timestamp=1 breaks xmit with fq
scheduler.  skb->tstamp might be "refreshed" using ktime_get_real(),
but fq expects CLOCK_MONOTONIC.

This patch removes all places in netfilter that check/set skb->tstamp:

1. To fix the bogus "start" time seen with conntrack timestamping for
   outgoing packets, never use skb->tstamp and always use current time.
2. In nfqueue and nflog, only use skb->tstamp for incoming packets,
   as determined by current hook (prerouting, input, forward).
3. xt_time has to use system clock as well rather than skb->tstamp.
   We could still use skb->tstamp for prerouting/input/foward, but
   I see no advantage to make this conditional.

Fixes: fb420d5d91c1 ("tcp/fq: move back to CLOCK_MONOTONIC")
Cc: Eric Dumazet 
Reported-by: Michal Soltys 
Signed-off-by: Florian Westphal 
Acked-by: Eric Dumazet 
Signed-off-by: Pablo Neira Ayuso

netfilter: nat: fix icmp id randomization

2019-04-15T05:31:50+00:00

Sven Auhagen reported that a 2nd ping request will fail if 'fully-random'
mode is used.

Reason is that if no proto information is given, min/max are both 0,
so we set the icmp id to 0 instead of chosing a random value between
0 and 65535.

Update test case as well to catch this, without fix this yields:
[..]
ERROR: cannot ping ns1 from ns2 with ip masquerade fully-random (attempt 2)
ERROR: cannot ping ns1 from ns2 with ipv6 masquerade fully-random (attempt 2)

... becaus 2nd ping clashes with existing 'id 0' icmp conntrack and gets
dropped.

Fixes: 203f2e78200c27e ("netfilter: nat: remove l4proto->unique_tuple")
Reported-by: Sven Auhagen 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: prevent shift wrap in nft_chain_parse_hook()

2019-04-15T05:31:50+00:00

I believe that "hook->num" can be up to UINT_MAX.  Shifting more than
31 bits would is undefined in C but in practice it would lead to shift
wrapping.  That would lead to an array overflow in nf_tables_addchain():

	ops->hook       = hook.type->hooks[ops->hooknum];

Fixes: fe19c04ca137 ("netfilter: nf_tables: remove nhooks field from struct nft_af_info")
Signed-off-by: Dan Carpenter 
Signed-off-by: Pablo Neira Ayuso

netfilter: ctnetlink: don't use conntrack/expect object addresses as id

2019-04-15T05:31:44+00:00

else, we leak the addresses to userspace via ctnetlink events
and dumps.

Compute an ID on demand based on the immutable parts of nf_conn struct.

Another advantage compared to using an address is that there is no
immediate re-use of the same ID in case the conntrack entry is freed and
reallocated again immediately.

Fixes: 3583240249ef ("[NETFILTER]: nf_conntrack_expect: kill unique ID")
Fixes: 7f85f914721f ("[NETFILTER]: nf_conntrack: kill unique ID")
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

ipvs: do not schedule icmp errors from tunnels

2019-04-13T12:52:57+00:00

We can receive ICMP errors from client or from
tunneling real server. While the former can be
scheduled to real server, the latter should
not be scheduled, they are decapsulated only when
existing connection is found.

Fixes: 6044eeffafbe ("ipvs: attempt to schedule icmp packets")
Signed-off-by: Julian Anastasov 
Signed-off-by: Simon Horman 
Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: initialize ct->timeout

2019-04-13T12:52:57+00:00

KMSAN started reporting an error when accessing ct->timeout for the
first time without initialization:

 BUG: KMSAN: uninit-value in __nf_ct_refresh_acct+0x1ae/0x470 net/netfilter/nf_conntrack_core.c:1765
 ...
 dump_stack+0x173/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:624
 __msan_warning+0x7a/0xf0 mm/kmsan/kmsan_instr.c:310
 __nf_ct_refresh_acct+0x1ae/0x470 net/netfilter/nf_conntrack_core.c:1765
 nf_ct_refresh_acct ./include/net/netfilter/nf_conntrack.h:201
 nf_conntrack_udp_packet+0xb44/0x1040 net/netfilter/nf_conntrack_proto_udp.c:122
 nf_conntrack_handle_packet net/netfilter/nf_conntrack_core.c:1605
 nf_conntrack_in+0x1250/0x26c9 net/netfilter/nf_conntrack_core.c:1696
 ...
 Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205
 kmsan_internal_poison_shadow+0x92/0x150 mm/kmsan/kmsan.c:159
 kmsan_kmalloc+0xa9/0x130 mm/kmsan/kmsan_hooks.c:173
 kmem_cache_alloc+0x554/0xb10 mm/slub.c:2789
 __nf_conntrack_alloc+0x16f/0x690 net/netfilter/nf_conntrack_core.c:1342
 init_conntrack+0x6cb/0x2490 net/netfilter/nf_conntrack_core.c:1421

Signed-off-by: Alexander Potapenko 
Fixes: cc16921351d8ba1 ("netfilter: conntrack: avoid same-timeout update")
Cc: Florian Westphal 
Acked-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: don't set related state for different outer address

2019-04-13T12:52:57+00:00

Luca Moro says:
 ------
The issue lies in the filtering of ICMP and ICMPv6 errors that include an
inner IP datagram.
For these packets, icmp_error_message() extract the ICMP error and inner
layer to search of a known state.
If a state is found the packet is tagged as related (IP_CT_RELATED).

The problem is that there is no correlation check between the inner and
outer layer of the packet.
So one can encapsulate an error with an inner layer matching a known state,
while its outer layer is directed to a filtered host.
In this case the whole packet will be tagged as related.
This has various implications from a rule bypass (if a rule to related
trafic is allow), to a known state oracle.

Unfortunately, we could not find a real statement in a RFC on how this case
should be filtered.
The closest we found is RFC5927 (Section 4.3) but it is not very clear.

A possible fix would be to check that the inner IP source is the same than
the outer destination.

We believed this kind of attack was not documented yet, so we started to
write a blog post about it.
You can find it attached to this mail (sorry for the extract quality).
It contains more technical details, PoC and discussion about the identified
behavior.
We discovered later that
https://www.gont.com.ar/papers/filtering-of-icmp-error-messages.pdf
described a similar attack concept in 2004 but without the stateful
filtering in mind.
 -----

This implements above suggested fix:
In icmp(v6) error handler, take outer destination address, then pass
that into the common function that does the "related" association.

After obtaining the nf_conn of the matching inner-headers connection,
check that the destination address of the opposite direction tuple
is the same as the outer address and only set RELATED if thats the case.

Reported-by: Luca Moro 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: add missing ->release_ops() in error path of newrule()

2019-03-20T07:32:58+00:00

->release_ops() callback releases resources and this is used in error path.
If nf_tables_newrule() fails after ->select_ops(), it should release
resources. but it can not call ->destroy() because that should be called
after ->init().
At this point, ->release_ops() should be used for releasing resources.

Test commands:
   modprobe -rv xt_tcpudp
   iptables-nft -I INPUT -m tcp   <-- error command
   lsmod

Result:
   Module                  Size  Used by
   xt_tcpudp              20480  2      <-- it should be 0

Fixes: b8e204006340 ("netfilter: nft_compat: use .release_ops and remove list of extension")
Signed-off-by: Taehee Yoo 
Signed-off-by: Pablo Neira Ayuso

netfilter: nft_redir: fix module autoload with ip4

2019-03-18T15:22:49+00:00

AF_INET4 does not exist.

Fixes: c78efc99c750 ("netfilter: nf_tables: nat: merge nft_redir protocol specific modules)"
Signed-off-by: Pablo Neira Ayuso