linux-stable.git/net/dccp/ipv4.c, branch linux-3.10.y

dccp/tcp: fix routing redirect race

2017-06-07T22:47:04+00:00

commit 45caeaa5ac0b4b11784ac6f932c0ad4c6b67cda0 upstream.

As Eric Dumazet pointed out this also needs to be fixed in IPv6.
v2: Contains the IPv6 tcp/Ipv6 dccp patches as well.

We have seen a few incidents lately where a dst_enty has been freed
with a dangling TCP socket reference (sk->sk_dst_cache) pointing to that
dst_entry. If the conditions/timings are right a crash then ensues when the
freed dst_entry is referenced later on. A Common crashing back trace is:

 #8 [] page_fault at ffffffff8163e648
    [exception RIP: __tcp_ack_snd_check+74]
.
.
 #9 [] tcp_rcv_established at ffffffff81580b64
#10 [] tcp_v4_do_rcv at ffffffff8158b54a
#11 [] tcp_v4_rcv at ffffffff8158cd02
#12 [] ip_local_deliver_finish at ffffffff815668f4
#13 [] ip_local_deliver at ffffffff81566bd9
#14 [] ip_rcv_finish at ffffffff8156656d
#15 [] ip_rcv at ffffffff81566f06
#16 [] __netif_receive_skb_core at ffffffff8152b3a2
#17 [] __netif_receive_skb at ffffffff8152b608
#18 [] netif_receive_skb at ffffffff8152b690
#19 [] vmxnet3_rq_rx_complete at ffffffffa015eeaf [vmxnet3]
#20 [] vmxnet3_poll_rx_only at ffffffffa015f32a [vmxnet3]
#21 [] net_rx_action at ffffffff8152bac2
#22 [] __do_softirq at ffffffff81084b4f
#23 [] call_softirq at ffffffff8164845c
#24 [] do_softirq at ffffffff81016fc5
#25 [] irq_exit at ffffffff81084ee5
#26 [] do_IRQ at ffffffff81648ff8

Of course it may happen with other NIC drivers as well.

It's found the freed dst_entry here:

 224 static bool tcp_in_quickack_mode(struct sock *sk)â©
 225 {â©
 226 â¹       const struct inet_connection_sock *icsk = inet_csk(sk);â©
 227 â¹       const struct dst_entry *dst = __sk_dst_get(sk);â©
 228 â©
 229 â¹       return (dst && dst_metric(dst, RTAX_QUICKACK)) ||â©
 230 â¹       â¹       (icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong);â©
 231 }â©

But there are other backtraces attributed to the same freed dst_entry in
netfilter code as well.

All the vmcores showed 2 significant clues:

- Remote hosts behind the default gateway had always been redirected to a
different gateway. A rtable/dst_entry will be added for that host. Making
more dst_entrys with lower reference counts. Making this more probable.

- All vmcores showed a postitive LockDroppedIcmps value, e.g:

LockDroppedIcmps                  267

A closer look at the tcp_v4_err() handler revealed that do_redirect() will run
regardless of whether user space has the socket locked. This can result in a
race condition where the same dst_entry cached in sk->sk_dst_entry can be
decremented twice for the same socket via:

do_redirect()->__sk_dst_check()-> dst_release().

Which leads to the dst_entry being prematurely freed with another socket
pointing to it via sk->sk_dst_cache and a subsequent crash.

To fix this skip do_redirect() if usespace has the socket locked. Instead let
the redirect take place later when user space does not have the socket
locked.

The dccp/IPv6 code is very similar in this respect, so fixing it there too.

As Eric Garver pointed out the following commit now invalidates routes. Which
can set the dst->obsolete flag so that ipv4_dst_check() returns null and
triggers the dst_release().

Fixes: ceb3320610d6 ("ipv4: Kill routes during PMTU/redirect updates.")
Cc: Eric Garver 
Cc: Hannes Sowa 
Signed-off-by: Jon Maxwell 
Signed-off-by: David S. Miller 
Signed-off-by: Willy Tarreau

dccp: fix out of bound access in dccp_v4_err()

2017-02-10T10:03:54+00:00

commit 6706a97fec963d6cb3f7fc2978ec1427b4651214 upstream.

dccp_v4_err() does not use pskb_may_pull() and might access garbage.

We only need 4 bytes at the beginning of the DCCP header, like TCP,
so the 8 bytes pulled in icmp_socket_deliver() are more than enough.

This patch might allow to process more ICMP messages, as some routers
are still limiting the size of reflected bytes to 28 (RFC 792), instead
of extended lengths (RFC 1812 4.3.2.3)

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Willy Tarreau

tcp: Remove TCPCT

2013-03-17T18:35:13+00:00

TCPCT uses option-number 253, reserved for experimental use and should
not be used in production environments.
Further, TCPCT does not fully implement RFC 6013.

As a nice side-effect, removing TCPCT increases TCP's performance for
very short flows:

Doing an apache-benchmark with -c 100 -n 100000, sending HTTP-requests
for files of 1KB size.

before this patch:
	average (among 7 runs) of 20845.5 Requests/Second
after:
	average (among 7 runs) of 21403.6 Requests/Second

Signed-off-by: Christoph Paasch 
Signed-off-by: David S. Miller

inet: Fix kmemleak in tcp_v4/6_syn_recv_sock and dccp_v4/6_request_recv_sock

2012-12-14T18:14:07+00:00

If in either of the above functions inet_csk_route_child_sock() or
__inet_inherit_port() fails, the newsk will not be freed:

unreferenced object 0xffff88022e8a92c0 (size 1592):
  comm "softirq", pid 0, jiffies 4294946244 (age 726.160s)
  hex dump (first 32 bytes):
    0a 01 01 01 0a 01 01 02 00 00 00 00 a7 cc 16 00  ................
    02 00 03 01 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [] kmemleak_alloc+0x21/0x3e
    [] kmem_cache_alloc+0xb5/0xc5
    [] sk_prot_alloc.isra.53+0x2b/0xcd
    [] sk_clone_lock+0x16/0x21e
    [] inet_csk_clone_lock+0x10/0x7b
    [] tcp_create_openreq_child+0x21/0x481
    [] tcp_v4_syn_recv_sock+0x3a/0x23b
    [] tcp_check_req+0x29f/0x416
    [] tcp_v4_do_rcv+0x161/0x2bc
    [] tcp_v4_rcv+0x6c9/0x701
    [] ip_local_deliver_finish+0x70/0xc4
    [] ip_local_deliver+0x4e/0x7f
    [] ip_rcv_finish+0x1fc/0x233
    [] ip_rcv+0x217/0x267
    [] __netif_receive_skb+0x49e/0x553
    [] netif_receive_skb+0x50/0x82

This happens, because sk_clone_lock initializes sk_refcnt to 2, and thus
a single sock_put() is not enough to free the memory. Additionally, things
like xfrm, memcg, cookie_values,... may have been initialized.
We have to free them properly.

This is fixed by forcing a call to tcp_done(), ending up in
inet_csk_destroy_sock, doing the final sock_put(). tcp_done() is necessary,
because it ends up doing all the cleanup on xfrm, memcg, cookie_values,
xfrm,...

Before calling tcp_done, we have to set the socket to SOCK_DEAD, to
force it entering inet_csk_destroy_sock. To avoid the warning in
inet_csk_destroy_sock, inet_num has to be set to 0.
As inet_csk_destroy_sock does a dec on orphan_count, we first have to
increase it.

Calling tcp_done() allows us to remove the calls to
tcp_clear_xmit_timer() and tcp_cleanup_congestion_control().

A similar approach is taken for dccp by calling dccp_done().

This is in the kernel since 093d282321 (tproxy: fix hash locking issue
when using port redirection in __inet_inherit_port()), thus since
version >= 2.6.37.

Signed-off-by: Christoph Paasch 
Signed-off-by: David S. Miller

ipv4: Prepare for change of rt->rt_iif encoding.

2012-07-23T23:36:26+00:00

Use inet_iif() consistently, and for TCP record the input interface of
cached RX dst in inet sock.

rt->rt_iif is going to be encoded differently, so that we can
legitimately cache input routes in the FIB info more aggressively.

When the input interface is "use SKB device index" the rt->rt_iif will
be set to zero.

This forces us to move the TCP RX dst cache installation into the ipv4
specific code, and as well it should since doing the route caching for
ipv6 is pointless at the moment since it is not inspected in the ipv6
input paths yet.

Also, remove the unlikely on dst->obsolete, all ipv4 dsts have
obsolete set to a non-zero value to force invocation of the check
callback.

Signed-off-by: David S. Miller

ipv4: Kill FLOWI_FLAG_RT_NOCACHE and associated code.

2012-07-20T20:36:54+00:00

Signed-off-by: David S. Miller

net: Pass optional SKB and SK arguments to dst_ops->{update_pmtu,redirect}()

2012-07-17T10:29:28+00:00

This will be used so that we can compose a full flow key.

Even though we have a route in this context, we need more.  In the
future the routes will be without destination address, source address,
etc. keying.  One ipv4 route will cover entire subnets, etc.

In this environment we have to have a way to possess persistent storage
for redirects and PMTU information.  This persistent storage will exist
in the FIB tables, and that's why we'll need to be able to rebuild a
full lookup flow key here.  Using that flow key will do a fib_lookup()
and create/update the persistent entry.

Signed-off-by: David S. Miller

ipv4: Add helper inet_csk_update_pmtu().

2012-07-16T10:28:06+00:00

This abstracts away the call to dst_ops->update_pmtu() so that we can
transparently handle the fact that, in the future, the dst itself can
be invalidated by the PMTU update (when we have non-host routes cached
in sockets).

So we try to rebuild the socket cached route after the method
invocation if necessary.

This isn't used by SCTP because it needs to cache dsts per-transport,
and thus will need it's own local version of this helper.

Signed-off-by: David S. Miller

net: Remove checks for dst_ops->redirect being NULL.

2012-07-12T07:41:25+00:00

No longer necessary.

Signed-off-by: David S. Miller

ipv4: Add redirect support to all protocol icmp error handlers.

2012-07-12T04:27:49+00:00

Signed-off-by: David S. Miller