linux-stable.git/net/ipv4, branch v3.16.52

tcp: fix tcp_mtu_probe() vs highest_sack

2018-01-01T20:52:02+00:00

commit 2b7cda9c35d3b940eb9ce74b30bbd5eb30db493d upstream.

Based on SNMP values provided by Roman, Yuchung made the observation
that some crashes in tcp_sacktag_walk() might be caused by MTU probing.

Looking at tcp_mtu_probe(), I found that when a new skb was placed
in front of the write queue, we were not updating tcp highest sack.

If one skb is freed because all its content was copied to the new skb
(for MTU probing), then tp->highest_sack could point to a now freed skb.

Bad things would then happen, including infinite loops.

This patch renames tcp_highest_sack_combine() and uses it
from tcp_mtu_probe() to fix the bug.

Note that I also removed one test against tp->sacked_out,
since we want to replace tp->highest_sack regardless of whatever
condition, since keeping a stale pointer to freed skb is a recipe
for disaster.

Fixes: a47e5a988a57 ("[TCP]: Convert highest_sack to sk_buff to allow direct access")
Signed-off-by: Eric Dumazet 
Reported-by: Alexei Starovoitov 
Reported-by: Roman Gushchin 
Reported-by: Oleksandr Natalenko 
Acked-by: Alexei Starovoitov 
Acked-by: Neal Cardwell 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

udp: fix bcast packet reception

2018-01-01T20:51:49+00:00

commit 996b44fcef8f216ea0b6b6e74468c5a77b5e341f upstream.

The commit bc044e8db796 ("udp: perform source validation for
mcast early demux") does not take into account that broadcast packets
lands in the same code path and they need different checks for the
source address - notably, zero source address are valid for bcast
and invalid for mcast.

As a result, 2nd and later broadcast packets with 0 source address
landing to the same socket are dropped. This breaks dhcp servers.

Since we don't have stringent performance requirements for ingress
broadcast traffic, fix it by disabling UDP early demux such traffic.

Reported-by: Hannes Frederic Sowa 
Fixes: bc044e8db796 ("udp: perform source validation for mcast early demux")
Signed-off-by: Paolo Abeni 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

udp: perform source validation for mcast early demux

2018-01-01T20:51:45+00:00

commit bc044e8db7962e727a75b591b9851ff2ac5cf846 upstream.

The UDP early demux can leverate the rx dst cache even for
multicast unconnected sockets.

In such scenario the ipv4 source address is validated only on
the first packet in the given flow. After that, when we fetch
the dst entry  from the socket rx cache, we stop enforcing
the rp_filter and we even start accepting any kind of martian
addresses.

Disabling the dst cache for unconnected multicast socket will
cause large performace regression, nearly reducing by half the
max ingress tput.

Instead we factor out a route helper to completely validate an
skb source address for multicast packets and we call it from
the UDP early demux for mcast packets landing on unconnected
sockets, after successful fetching the related cached dst entry.

This still gives a measurable, but limited performance
regression:

		rp_filter = 0		rp_filter = 1
edmux disabled:	1182 Kpps		1127 Kpps
edmux before:	2238 Kpps		2238 Kpps
edmux after:	2037 Kpps		2019 Kpps

The above figures are on top of current net tree.
Applying the net-next commit 6e617de84e87 ("net: avoid a full
fib lookup when rp_filter is disabled.") the delta with
rp_filter == 0 will decrease even more.

Fixes: 421b3885bf6d ("udp: ipv4: Add udp early demux")
Signed-off-by: Paolo Abeni 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

IPv4: early demux can return an error code

2018-01-01T20:51:45+00:00

commit 7487449c86c65202b3b725c4524cb48dd65e4e6f upstream.

Currently no error is emitted, but this infrastructure will
used by the next patch to allow source address validation
for mcast sockets.
Since early demux can do a route lookup and an ipv4 route
lookup can return an error code this is consistent with the
current ipv4 route infrastructure.

Signed-off-by: Paolo Abeni 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16:
 - Drop change to net_protocol::early_demux_handler
 - Keep using NET_INC_STATS_BH() in ip_rcv_finish()
 - Fix up additional return statement in udp_v4_early_demux()
 - Adjust context]
Signed-off-by: Ben Hutchings

ipv4: fix broadcast packets reception

2018-01-01T20:51:45+00:00

commit ad0ea1989cc4d5905941d0a9e62c63ad6d859cef upstream.

Currently, ingress ipv4 broadcast datagrams are dropped since,
in udp_v4_early_demux(), ip_check_mc_rcu() is invoked even on
bcast packets.

This patch addresses the issue, invoking ip_check_mc_rcu()
only for mcast packets.

Fixes: 6e5403093261 ("ipv4/udp: Verify multicast group is ours in upd_v4_early_demux()")
Signed-off-by: Paolo Abeni 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

vti: fix use after free in vti_tunnel_xmit/vti6_tnl_xmit

2018-01-01T20:51:42+00:00

commit 36f6ee22d2d66046e369757ec6bbe1c482957ba6 upstream.

When running LTP IPsec tests, KASan might report:

BUG: KASAN: use-after-free in vti_tunnel_xmit+0xeee/0xff0 [ip_vti]
Read of size 4 at addr ffff880dc6ad1980 by task swapper/0/0
...
Call Trace:
  
  dump_stack+0x63/0x89
  print_address_description+0x7c/0x290
  kasan_report+0x28d/0x370
  ? vti_tunnel_xmit+0xeee/0xff0 [ip_vti]
  __asan_report_load4_noabort+0x19/0x20
  vti_tunnel_xmit+0xeee/0xff0 [ip_vti]
  ? vti_init_net+0x190/0x190 [ip_vti]
  ? save_stack_trace+0x1b/0x20
  ? save_stack+0x46/0xd0
  dev_hard_start_xmit+0x147/0x510
  ? icmp_echo.part.24+0x1f0/0x210
  __dev_queue_xmit+0x1394/0x1c60
...
Freed by task 0:
  save_stack_trace+0x1b/0x20
  save_stack+0x46/0xd0
  kasan_slab_free+0x70/0xc0
  kmem_cache_free+0x81/0x1e0
  kfree_skbmem+0xb1/0xe0
  kfree_skb+0x75/0x170
  kfree_skb_list+0x3e/0x60
  __dev_queue_xmit+0x1298/0x1c60
  dev_queue_xmit+0x10/0x20
  neigh_resolve_output+0x3a8/0x740
  ip_finish_output2+0x5c0/0xe70
  ip_finish_output+0x4ba/0x680
  ip_output+0x1c1/0x3a0
  xfrm_output_resume+0xc65/0x13d0
  xfrm_output+0x1e4/0x380
  xfrm4_output_finish+0x5c/0x70

Can be fixed if we get skb->len before dst_output().

Fixes: b9959fd3b0fa ("vti: switch to new ip tunnel code")
Fixes: 22e1b23dafa8 ("vti6: Support inter address family tunneling.")
Signed-off-by: Alexey Kodanev 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

tcp: fastopen: fix on syn-data transmit failure

2018-01-01T20:51:33+00:00

commit b5b7db8d680464b1d631fd016f5e093419f0bfd9 upstream.

Our recent change exposed a bug in TCP Fastopen Client that syzkaller
found right away [1]

When we prepare skb with SYN+DATA, we attempt to transmit it,
and we update socket state as if the transmit was a success.

In socket RTX queue we have two skbs, one with the SYN alone,
and a second one containing the DATA.

When (malicious) ACK comes in, we now complain that second one had no
skb_mstamp.

The proper fix is to make sure that if the transmit failed, we do not
pretend we sent the DATA skb, and make it our send_head.

When 3WHS completes, we can now send the DATA right away, without having
to wait for a timeout.

[1]
WARNING: CPU: 0 PID: 100189 at net/ipv4/tcp_input.c:3117 tcp_clean_rtx_queue+0x2057/0x2ab0 net/ipv4/tcp_input.c:3117()

 WARN_ON_ONCE(last_ackt == 0);

Modules linked in:
CPU: 0 PID: 100189 Comm: syz-executor1 Not tainted
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 ffff8800b35cb1d8 ffffffff81cad00d 0000000000000000
 ffffffff828a4347 ffff88009f86c080 ffffffff8316eb20 0000000000000d7f
 ffff8800b35cb220 ffffffff812c33c2 ffff8800baad2440 00000009d46575c0
Call Trace:
 [] __dump_stack
 [] dump_stack+0xc1/0x124
 [] warn_slowpath_common+0xe2/0x150
 [] warn_slowpath_null+0x2e/0x40
 [] tcp_clean_rtx_queue+0x2057/0x2ab0 n
 [] tcp_ack+0x151d/0x3930
 [] tcp_rcv_state_process+0x1c69/0x4fd0
 [] tcp_v4_do_rcv+0x54f/0x7c0
 [] sk_backlog_rcv
 [] __release_sock+0x12b/0x3a0
 [] release_sock+0x5e/0x1c0
 [] inet_wait_for_connect
 [] __inet_stream_connect+0x545/0xc50
 [] tcp_sendmsg_fastopen
 [] tcp_sendmsg+0x2298/0x35a0
 [] inet_sendmsg+0xe5/0x520
 [] sock_sendmsg_nosec
 [] sock_sendmsg+0xcf/0x110

Fixes: 8c72c65b426b ("tcp: update skb->skb_mstamp more carefully")
Fixes: 783237e8daf1 ("net-tcp: Fast Open client - sending SYN-data")
Signed-off-by: Eric Dumazet 
Reported-by: Dmitry Vyukov 
Cc: Neal Cardwell 
Cc: Yuchung Cheng 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

Revert "net: use lib/percpu_counter API for fragmentation mem accounting"

2017-11-26T13:50:30+00:00

commit fb452a1aa3fd4034d7999e309c5466ff2d7005aa upstream.

This reverts commit 6d7b857d541ecd1d9bd997c97242d4ef94b19de2.

There is a bug in fragmentation codes use of the percpu_counter API,
that can cause issues on systems with many CPUs.

The frag_mem_limit() just reads the global counter (fbc->count),
without considering other CPUs can have upto batch size (130K) that
haven't been subtracted yet.  Due to the 3MBytes lower thresh limit,
this become dangerous at >=24 CPUs (3*1024*1024/130000=24).

The correct API usage would be to use __percpu_counter_compare() which
does the right thing, and takes into account the number of (online)
CPUs and batch size, to account for this and call __percpu_counter_sum()
when needed.

We choose to revert the use of the lib/percpu_counter API for frag
memory accounting for several reasons:

1) On systems with CPUs > 24, the heavier fully locked
   __percpu_counter_sum() is always invoked, which will be more
   expensive than the atomic_t that is reverted to.

Given systems with more than 24 CPUs are becoming common this doesn't
seem like a good option.  To mitigate this, the batch size could be
decreased and thresh be increased.

2) The add_frag_mem_limit+sub_frag_mem_limit pairs happen on the RX
   CPU, before SKBs are pushed into sockets on remote CPUs.  Given
   NICs can only hash on L2 part of the IP-header, the NIC-RXq's will
   likely be limited.  Thus, a fair chance that atomic add+dec happen
   on the same CPU.

Revert note that commit 1d6119baf061 ("net: fix percpu memory leaks")
removed init_frag_mem_limit() and instead use inet_frags_init_net().
After this revert, inet_frags_uninit_net() becomes empty.

Fixes: 6d7b857d541e ("net: use lib/percpu_counter API for fragmentation mem accounting")
Fixes: 1d6119baf061 ("net: fix percpu memory leaks")
Signed-off-by: Jesper Dangaard Brouer 
Acked-by: Florian Westphal 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

netfilter: Fix switch statement warnings with recent gcc.

2017-11-11T13:33:54+00:00

commit c1f866767777d1c6abae0ec57effffcb72017c00 upstream.

More recent GCC warns about two kinds of switch statement uses:

1) Switching on an enumeration, but not having an explicit case
   statement for all members of the enumeration.  To show the
   compiler this is intentional, we simply add a default case
   with nothing more than a break statement.

2) Switching on a boolean value.  I think this warning is dumb
   but nevertheless you get it wholesale with -Wswitch.

This patch cures all such warnings in netfilter.

Signed-off-by: David S. Miller 
Acked-by: Pablo Neira Ayuso 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Ben Hutchings

ipv4: fix NULL dereference in free_fib_info_rcu()

2017-11-11T13:33:21+00:00

commit 187e5b3ac84d3421d2de3aca949b2791fbcad554 upstream.

If fi->fib_metrics could not be allocated in fib_create_info()
we attempt to dereference a NULL pointer in free_fib_info_rcu() :

    m = fi->fib_metrics;
    if (m != &dst_default_metrics && atomic_dec_and_test(&m->refcnt))
            kfree(m);

Before my recent patch, we used to call kfree(NULL) and nothing wrong
happened.

Instead of using RCU to defer freeing while we are under memory stress,
it seems better to take immediate action.

This was reported by syzkaller team.

Fixes: 3fb07daff8e9 ("ipv4: add reference counting to metrics")
Signed-off-by: Eric Dumazet 
Reported-by: Dmitry Vyukov 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings