linux-stable.git/net/ipv4, branch v4.12.2

tcp: reset sk_rx_dst in tcp_disconnect()

2017-06-25T16:23:07+00:00

We have to reset the sk->sk_rx_dst when we disconnect a TCP
connection, because otherwise when we re-connect it this
dst reference is simply overridden in tcp_finish_connect().

This fixes a dst leak which leads to a loopback dev refcnt
leak. It is a long-standing bug, Kevin reported a very similar
(if not same) bug before. Thanks to Andrei for providing such
a reliable reproducer which greatly narrows down the problem.

Fixes: 41063e9dd119 ("ipv4: Early TCP socket demux.")
Reported-by: Andrei Vagin 
Reported-by: Kevin Xu 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

net: account for current skb length when deciding about UFO

2017-06-23T17:29:38+00:00

Our customer encountered stuck NFS writes for blocks starting at specific
offsets w.r.t. page boundary caused by networking stack sending packets via
UFO enabled device with wrong checksum. The problem can be reproduced by
composing a long UDP datagram from multiple parts using MSG_MORE flag:

  sendto(sd, buff, 1000, MSG_MORE, ...);
  sendto(sd, buff, 1000, MSG_MORE, ...);
  sendto(sd, buff, 3000, 0, ...);

Assume this packet is to be routed via a device with MTU 1500 and
NETIF_F_UFO enabled. When second sendto() gets into __ip_append_data(),
this condition is tested (among others) to decide whether to call
ip_ufo_append_data():

  ((length + fragheaderlen) > mtu) || (skb && skb_is_gso(skb))

At the moment, we already have skb with 1028 bytes of data which is not
marked for GSO so that the test is false (fragheaderlen is usually 20).
Thus we append second 1000 bytes to this skb without invoking UFO. Third
sendto(), however, has sufficient length to trigger the UFO path so that we
end up with non-UFO skb followed by a UFO one. Later on, udp_send_skb()
uses udp_csum() to calculate the checksum but that assumes all fragments
have correct checksum in skb->csum which is not true for UFO fragments.

When checking against MTU, we need to add skb->len to length of new segment
if we already have a partially filled skb and fragheaderlen only if there
isn't one.

In the IPv6 case, skb can only be null if this is the first segment so that
we have to use headersize (length of the first IPv6 header) rather than
fragheaderlen (length of IPv6 header of further fragments) for skb == NULL.

Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach")
Fixes: e4c5e13aa45c ("ipv6: Should use consistent conditional judgement for
	ip6 fragment between __ip6_append_data and ip6_finish_output")
Signed-off-by: Michal Kubecek 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller

igmp: add a missing spin_lock_init()

2017-06-20T19:51:57+00:00

Andrey reported a lockdep warning on non-initialized
spinlock:

 INFO: trying to register non-static key.
 the code is fine but needs lockdep annotation.
 turning off the locking correctness validator.
 CPU: 1 PID: 4099 Comm: a.out Not tainted 4.12.0-rc6+ #9
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 Call Trace:
  __dump_stack lib/dump_stack.c:16
  dump_stack+0x292/0x395 lib/dump_stack.c:52
  register_lock_class+0x717/0x1aa0 kernel/locking/lockdep.c:755
  ? 0xffffffffa0000000
  __lock_acquire+0x269/0x3690 kernel/locking/lockdep.c:3255
  lock_acquire+0x22d/0x560 kernel/locking/lockdep.c:3855
  __raw_spin_lock_bh ./include/linux/spinlock_api_smp.h:135
  _raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:175
  spin_lock_bh ./include/linux/spinlock.h:304
  ip_mc_clear_src+0x27/0x1e0 net/ipv4/igmp.c:2076
  igmpv3_clear_delrec+0xee/0x4f0 net/ipv4/igmp.c:1194
  ip_mc_destroy_dev+0x4e/0x190 net/ipv4/igmp.c:1736

We miss a spin_lock_init() in igmpv3_add_delrec(), probably
because previously we never use it on this code path. Since
we already unlink it from the global mc_tomb list, it is
probably safe not to acquire this spinlock here. It does not
harm to have it although, to avoid conditional locking.

Fixes: c38b7d327aaf ("igmp: acquire pmc lock for ip_mc_clear_src()")
Reported-by: Andrey Konovalov 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

ip_tunnel: fix potential issue in ip_tunnel_rcv

2017-06-16T16:01:29+00:00

When ip_tunnel_rcv fails, the tun_dst won't be freed, so call
dst_release to free it in error code path.

Fixes: 2e15ea390e6f ("ip_gre: Add support to collect tunnel metadata.")
Acked-by: Eric Dumazet 
Acked-by: Pravin B Shelar 
Tested-by: Zhang Shengju 
Signed-off-by: Haishuang Yan 
Signed-off-by: David S. Miller

net: don't global ICMP rate limit packets originating from loopback

2017-06-14T19:33:58+00:00

Florian Weimer seems to have a glibc test-case which requires that
loopback interfaces does not get ICMP ratelimited.  This was broken by
commit c0303efeab73 ("net: reduce cycles spend on ICMP replies that
gets rate limited").

An ICMP response will usually be routed back-out the same incoming
interface.  Thus, take advantage of this and skip global ICMP
ratelimit when the incoming device is loopback.  In the unlikely event
that the outgoing it not loopback, due to strange routing policy
rules, ICMP rate limiting still works via peer ratelimiting via
icmpv4_xrlim_allow().  Thus, we should still comply with RFC1812
(section 4.3.2.8 "Rate Limiting").

This seems to fix the reproducer given by Florian.  While still
avoiding to perform expensive and unneeded outgoing route lookup for
rate limited packets (in the non-loopback case).

Fixes: c0303efeab73 ("net: reduce cycles spend on ICMP replies that gets rate limited")
Reported-by: Florian Weimer 
Reported-by: "H.J. Lu" 
Signed-off-by: Jesper Dangaard Brouer 
Signed-off-by: David S. Miller

igmp: acquire pmc lock for ip_mc_clear_src()

2017-06-13T16:51:37+00:00

Andrey reported a use-after-free in add_grec():

        for (psf = *psf_list; psf; psf = psf_next) {
		...
                psf_next = psf->sf_next;

where the struct ip_sf_list's were already freed by:

 kfree+0xe8/0x2b0 mm/slub.c:3882
 ip_mc_clear_src+0x69/0x1c0 net/ipv4/igmp.c:2078
 ip_mc_dec_group+0x19a/0x470 net/ipv4/igmp.c:1618
 ip_mc_drop_socket+0x145/0x230 net/ipv4/igmp.c:2609
 inet_release+0x4e/0x1c0 net/ipv4/af_inet.c:411
 sock_release+0x8d/0x1e0 net/socket.c:597
 sock_close+0x16/0x20 net/socket.c:1072

This happens because we don't hold pmc->lock in ip_mc_clear_src()
and a parallel mr_ifc_timer timer could jump in and access them.

The RCU lock is there but it is merely for pmc itself, this
spinlock could actually ensure we don't access them in parallel.

Thanks to Eric and Long for discussion on this bug.

Reported-by: Andrey Konovalov 
Cc: Eric Dumazet 
Cc: Xin Long 
Signed-off-by: Cong Wang 
Reviewed-by: Xin Long 
Signed-off-by: David S. Miller

net: ipmr: Fix some mroute forwarding issues in vrf's

2017-06-11T22:15:06+00:00

This patch fixes two issues:

1) When forwarding on *,G mroutes that are in a vrf, the
kernel was dropping information about the actual incoming
interface when calling ip_mr_forward from ip_mr_input.
This caused ip_mr_forward to send the multicast packet
back out the incoming interface.  Fix this by
modifying ip_mr_forward to be handed the correctly
resolved dev.

2) When a unresolved cache entry is created we store
the incoming skb on the unresolved cache entry and
upon mroute resolution from the user space daemon,
we attempt to forward the packet.  Again we were
not resolving to the correct incoming device for
a vrf scenario, before calling ip_mr_forward.
Fix this by resolving to the correct interface
and calling ip_mr_forward with the result.

Fixes: e58e41596811 ("net: Enable support for VRF with ipv4 multicast")
Signed-off-by: Donald Sharp 
Acked-by: David Ahern 
Acked-by: Nikolay Aleksandrov 
Reviewed-by: Yotam Gigi 
Signed-off-by: David S. Miller

net: Fix inconsistent teardown and release of private netdev state.

2017-06-07T19:53:24+00:00

Network devices can allocate reasources and private memory using
netdev_ops->ndo_init().  However, the release of these resources
can occur in one of two different places.

Either netdev_ops->ndo_uninit() or netdev->destructor().

The decision of which operation frees the resources depends upon
whether it is necessary for all netdev refs to be released before it
is safe to perform the freeing.

netdev_ops->ndo_uninit() presumably can occur right after the
NETDEV_UNREGISTER notifier completes and the unicast and multicast
address lists are flushed.

netdev->destructor(), on the other hand, does not run until the
netdev references all go away.

Further complicating the situation is that netdev->destructor()
almost universally does also a free_netdev().

This creates a problem for the logic in register_netdevice().
Because all callers of register_netdevice() manage the freeing
of the netdev, and invoke free_netdev(dev) if register_netdevice()
fails.

If netdev_ops->ndo_init() succeeds, but something else fails inside
of register_netdevice(), it does call ndo_ops->ndo_uninit().  But
it is not able to invoke netdev->destructor().

This is because netdev->destructor() will do a free_netdev() and
then the caller of register_netdevice() will do the same.

However, this means that the resources that would normally be released
by netdev->destructor() will not be.

Over the years drivers have added local hacks to deal with this, by
invoking their destructor parts by hand when register_netdevice()
fails.

Many drivers do not try to deal with this, and instead we have leaks.

Let's close this hole by formalizing the distinction between what
private things need to be freed up by netdev->destructor() and whether
the driver needs unregister_netdevice() to perform the free_netdev().

netdev->priv_destructor() performs all actions to free up the private
resources that used to be freed by netdev->destructor(), except for
free_netdev().

netdev->needs_free_netdev is a boolean that indicates whether
free_netdev() should be done at the end of unregister_netdevice().

Now, register_netdevice() can sanely release all resources after
ndo_ops->ndo_init() succeeds, by invoking both ndo_ops->ndo_uninit()
and netdev->priv_destructor().

And at the end of unregister_netdevice(), we invoke
netdev->priv_destructor() and optionally call free_netdev().

Signed-off-by: David S. Miller

net: ping: do not abuse udp_poll()

2017-06-05T02:56:55+00:00

Alexander reported various KASAN messages triggered in recent kernels

The problem is that ping sockets should not use udp_poll() in the first
place, and recent changes in UDP stack finally exposed this old bug.

Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind")
Fixes: 6d0bfe226116 ("net: ipv6: Add IPv6 support to the ping socket.")
Signed-off-by: Eric Dumazet 
Reported-by: Sasha Levin 
Cc: Solar Designer 
Cc: Vasiliy Kulikov 
Cc: Lorenzo Colitti 
Acked-By: Lorenzo Colitti 
Tested-By: Lorenzo Colitti 
Signed-off-by: David S. Miller

tcp: disallow cwnd undo when switching congestion control

2017-06-02T18:18:13+00:00

When the sender switches its congestion control during loss
recovery, if the recovery is spurious then it may incorrectly
revert cwnd and ssthresh to the older values set by a previous
congestion control. Consider a congestion control (like BBR)
that does not use ssthresh and keeps it infinite: the connection
may incorrectly revert cwnd to an infinite value when switching
from BBR to another congestion control.

This patch fixes it by disallowing such cwnd undo operation
upon switching congestion control.  Note that undo_marker
is not reset s.t. the packets that were incorrectly marked
lost would be corrected. We only avoid undoing the cwnd in
tcp_undo_cwnd_reduction().

Signed-off-by: Yuchung Cheng 
Signed-off-by: Soheil Hassas Yeganeh 
Signed-off-by: Neal Cardwell 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller