linux-stable.git/net/netfilter, branch v4.9.45

netfilter: nf_ct_ext: fix possible panic after nf_ct_extend_unregister

2017-08-25T00:12:18+00:00

commit 9c3f3794926a997b1cab6c42480ff300efa2d162 upstream.

If one cpu is doing nf_ct_extend_unregister while another cpu is doing
__nf_ct_ext_add_length, then we may hit BUG_ON(t == NULL). Moreover,
there's no synchronize_rcu invocation after set nf_ct_ext_types[id] to
NULL, so it's possible that we may access invalid pointer.

But actually, most of the ct extends are built-in, so the problem listed
above will not happen. However, there are two exceptions: NF_CT_EXT_NAT
and NF_CT_EXT_SYNPROXY.

For _EXT_NAT, the panic will not happen, since adding the nat extend and
unregistering the nat extend are located in the same file(nf_nat_core.c),
this means that after the nat module is removed, we cannot add the nat
extend too.

For _EXT_SYNPROXY, synproxy extend may be added by init_conntrack, while
synproxy extend unregister will be done by synproxy_core_exit. So after
nf_synproxy_core.ko is removed, we may still try to add the synproxy
extend, then kernel panic may happen.

I know it's very hard to reproduce this issue, but I can play a tricky
game to make it happen very easily :)

Step 1. Enable SYNPROXY for tcp dport 1234 at FORWARD hook:
  # iptables -I FORWARD -p tcp --dport 1234 -j SYNPROXY
Step 2. Queue the syn packet to the userspace at raw table OUTPUT hook.
        Also note, in the userspace we only add a 20s' delay, then
        reinject the syn packet to the kernel:
  # iptables -t raw -I OUTPUT -p tcp --syn -j NFQUEUE --queue-num 1
Step 3. Using "nc 2.2.2.2 1234" to connect the server.
Step 4. Now remove the nf_synproxy_core.ko quickly:
  # iptables -F FORWARD
  # rmmod ipt_SYNPROXY
  # rmmod nf_synproxy_core
Step 5. After 20s' delay, the syn packet is reinjected to the kernel.

Now you will see the panic like this:
  kernel BUG at net/netfilter/nf_conntrack_extend.c:91!
  Call Trace:
   ? __nf_ct_ext_add_length+0x53/0x3c0 [nf_conntrack]
   init_conntrack+0x12b/0x600 [nf_conntrack]
   nf_conntrack_in+0x4cc/0x580 [nf_conntrack]
   ipv4_conntrack_local+0x48/0x50 [nf_conntrack_ipv4]
   nf_reinject+0x104/0x270
   nfqnl_recv_verdict+0x3e1/0x5f9 [nfnetlink_queue]
   ? nfqnl_recv_verdict+0x5/0x5f9 [nfnetlink_queue]
   ? nla_parse+0xa0/0x100
   nfnetlink_rcv_msg+0x175/0x6a9 [nfnetlink]
   [...]

One possible solution is to make NF_CT_EXT_SYNPROXY extend built-in, i.e.
introduce nf_conntrack_synproxy.c and only do ct extend register and
unregister in it, similar to nf_conntrack_timeout.c.

But having such a obscure restriction of nf_ct_extend_unregister is not a
good idea, so we should invoke synchronize_rcu after set nf_ct_ext_types
to NULL, and check the NULL pointer when do __nf_ct_ext_add_length. Then
it will be easier if we add new ct extend in the future.

Last, we use kfree_rcu to free nf_ct_ext, so rcu_barrier() is unnecessary
anymore, remove it too.

Signed-off-by: Liping Zhang 
Acked-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Cc: Stefan Bader 
Signed-off-by: Greg Kroah-Hartman

ipvs: SNAT packet replies only for NATed connections

2017-07-27T22:08:00+00:00

commit 3c5ab3f395d66a9e4e937fcfdf6ebc63894f028b upstream.

We do not check if packet from real server is for NAT
connection before performing SNAT. This causes problems
for setups that use DR/TUN and allow local clients to
access the real server directly, for example:

- local client in director creates IPVS-DR/TUN connection
CIP->VIP and the request packets are routed to RIP.
Talks are finished but IPVS connection is not expired yet.

- second local client creates non-IPVS connection CIP->RIP
with same reply tuple RIP->CIP and when replies are received
on LOCAL_IN we wrongly assign them for the first client
connection because RIP->CIP matches the reply direction.
As result, IPVS SNATs replies for non-IPVS connections.

The problem is more visible to local UDP clients but in rare
cases it can happen also for TCP or remote clients when the
real server sends the reply traffic via the director.

So, better to be more precise for the reply traffic.
As replies are not expected for DR/TUN connections, better
to not touch them.

Reported-by: Nick Moriarty 
Tested-by: Nick Moriarty 
Signed-off-by: Julian Anastasov 
Signed-off-by: Simon Horman 
Signed-off-by: Greg Kroah-Hartman

netfilter: synproxy: fix conntrackd interaction

2017-07-05T12:40:16+00:00

commit 87e94dbc210a720a34be5c1174faee5c84be963e upstream.

This patch fixes the creation of connection tracking entry from
netlink when synproxy is used. It was missing the addition of
the synproxy extension.

This was causing kernel crashes when a conntrack entry created by
conntrackd was used after the switch of traffic from active node
to the passive node.

Signed-off-by: Eric Leblond 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: xt_TCPMSS: add more sanity tests on tcph->doff

2017-07-05T12:40:16+00:00

commit 2638fd0f92d4397884fd991d8f4925cb3f081901 upstream.

Denys provided an awesome KASAN report pointing to an use
after free in xt_TCPMSS

I have provided three patches to fix this issue, either in xt_TCPMSS or
in xt_tcpudp.c. It seems xt_TCPMSS patch has the smallest possible
impact.

Signed-off-by: Eric Dumazet 
Reported-by: Denys Fedoryshchenko 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: nft_log: restrict the log prefix length to 127

2017-06-17T04:41:58+00:00

[ Upstream commit 5ce6b04ce96896e8a79e6f60740ced911eaac7a4 ]

First, log prefix will be truncated to NF_LOG_PREFIXLEN-1, i.e. 127,
at nf_log_packet(), so the extra part is useless.

Second, after adding a log rule with a very very long prefix, we will
fail to dump the nft rules after this _special_ one, but acctually,
they do exist. For example:
  # name_65000=$(printf "%0.sQ" {1..65000})
  # nft add rule filter output log prefix "$name_65000"
  # nft add rule filter output counter
  # nft add rule filter output counter
  # nft list chain filter output
  table ip filter {
      chain output {
          type filter hook output priority 0; policy accept;
      }
  }

So now, restrict the log prefix length to NF_LOG_PREFIXLEN-1.

Fixes: 96518518cc41 ("netfilter: add nftables")
Signed-off-by: Liping Zhang 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_tables: fix set->nelems counting with no NLM_F_EXCL

2017-06-17T04:41:57+00:00

[ Upstream commit 35d0ac9070ef619e3bf44324375878a1c540387b ]

If the element exists and no NLM_F_EXCL is specified, do not bump
set->nelems, otherwise we leak one set element slot. This problem
amplifies if the set is full since the abort path always decrements the
counter for the -ENFILE case too, giving one spare extra slot.

Fix this by moving set->nelems update to nft_add_set_elem() after
successful element insertion. Moreover, remove the element if the set is
full so there is no need to rely on the abort path to undo things
anymore.

Fixes: c016c7e45ddf ("netfilter: nf_tables: honor NLM_F_EXCL flag in set element insertion")
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_conntrack_sip: fix wrong memory initialisation

2017-06-17T04:41:49+00:00

commit da2f27e9e615d1c799c9582b15262458da61fddc upstream.

In commit 82de0be6862cd ("netfilter: Add helper array
register/unregister functions"),
struct nf_conntrack_helper sip[MAX_PORTS][4] was changed to
sip[MAX_PORTS * 4], so the memory init should have been changed to
memset(&sip[4 * i], 0, 4 * sizeof(sip[i]));

But as the sip[] table is allocated in the BSS, it is already set to 0

Fixes: 82de0be6862cd ("netfilter: Add helper array register/unregister functions")
Signed-off-by: Christophe Leroy 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: nft_set_rbtree: handle element re-addition after deletion

2017-06-14T13:06:06+00:00

commit d2df92e98a34a5619dadd29c6291113c009181e7 upstream.

The existing code selects no next branch to be inspected when
re-inserting an inactive element into the rb-tree, looping endlessly.
This patch restricts the check for active elements to the EEXIST case
only.

Fixes: e701001e7cbe ("netfilter: nft_rbtree: allow adjacent intervals with dynamic updates")
Reported-by: Wolfgang Bumiller 
Tested-by: Wolfgang Bumiller 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: conntrack: refine gc worker heuristics, redux

2017-03-12T05:41:53+00:00

commit e5072053b09642b8ff417d47da05b84720aea3ee upstream.

This further refines the changes made to conntrack gc_worker in
commit e0df8cae6c16 ("netfilter: conntrack: refine gc worker heuristics").

The main idea of that change was to reduce the scan interval when evictions
take place.

However, on the reporters' setup, there are 1-2 million conntrack entries
in total and roughly 8k new (and closing) connections per second.

In this case we'll always evict at least one entry per gc cycle and scan
interval is always at 1 jiffy because of this test:

 } else if (expired_count) {
     gc_work->next_gc_run /= 2U;
     next_run = msecs_to_jiffies(1);

being true almost all the time.

Given we scan ~10k entries per run its clearly wrong to reduce interval
based on nonzero eviction count, it will only waste cpu cycles since a vast
majorities of conntracks are not timed out.

Thus only look at the ratio (scanned entries vs. evicted entries) to make
a decision on whether to reduce or not.

Because evictor is supposed to only kick in when system turns idle after
a busy period, pick a high ratio -- this makes it 50%.  We thus keep
the idea of increasing scan rate when its likely that table contains many
expired entries.

In order to not let timed-out entries hang around for too long
(important when using event logging, in which case we want to timely
destroy events), we now scan the full table within at most
GC_MAX_SCAN_JIFFIES (16 seconds) even in worst-case scenario where all
timed-out entries sit in same slot.

I tested this with a vm under synflood (with
sysctl net.netfilter.nf_conntrack_tcp_timeout_syn_recv=3).

While flood is ongoing, interval now stays at its max rate
(GC_MAX_SCAN_JIFFIES / GC_MAX_BUCKETS_DIV -> 125ms).

With feedback from Nicolas Dichtel.

Reported-by: Denys Fedoryshchenko 
Cc: Nicolas Dichtel 
Fixes: b87a2f9199ea82eaadc ("netfilter: conntrack: add gc worker to remove timed-out entries")
Signed-off-by: Florian Westphal 
Tested-by: Nicolas Dichtel 
Acked-by: Nicolas Dichtel 
Tested-by: Denys Fedoryshchenko 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: conntrack: remove GC_MAX_EVICTS break

2017-03-12T05:41:53+00:00

commit 524b698db06b9b6da7192e749f637904e2f62d7b upstream.

Instead of breaking loop and instant resched, don't bother checking
this in first place (the loop calls cond_resched for every bucket anyway).

Suggested-by: Nicolas Dichtel 
Signed-off-by: Florian Westphal 
Acked-by: Nicolas Dichtel 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman