linux.git/include/net, branch v3.14.41

ipv6: protect skb->sk accesses from recursive dereference inside the stack

2015-04-29T08:31:46+00:00

[ Upstream commit f60e5990d9c1424af9dbca60a23ba2a1c7c1ce90 ]

We should not consult skb->sk for output decisions in xmit recursion
levels > 0 in the stack. Otherwise local socket settings could influence
the result of e.g. tunnel encapsulation process.

ipv6 does not conform with this in three places:

1) ip6_fragment: we do consult ipv6_npinfo for frag_size

2) sk_mc_loop in ipv6 uses skb->sk and checks if we should
   loop the packet back to the local socket

3) ip6_skb_dst_mtu could query the settings from the user socket and
   force a wrong MTU

Furthermore:
In sk_mc_loop we could potentially land in WARN_ON(1) if we use a
PF_PACKET socket ontop of an IPv6-backed vxlan device.

Reuse xmit_recursion as we are currently only interested in protecting
tunnel devices.

Cc: Jiri Pirko 
Signed-off-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: tcp: get rid of ugly unicast_sock

2015-02-27T01:50:12+00:00

[ Upstream commit bdbbb8527b6f6a358dbcb70dac247034d665b8e4 ]

In commit be9f4a44e7d41 ("ipv4: tcp: remove per net tcp_sock")
I tried to address contention on a socket lock, but the solution
I chose was horrible :

commit 3a7c384ffd57e ("ipv4: tcp: unicast_sock should not land outside
of TCP stack") addressed a selinux regression.

commit 0980e56e506b ("ipv4: tcp: set unicast_sock uc_ttl to -1")
took care of another regression.

commit b5ec8eeac46 ("ipv4: fix ip_send_skb()") fixed another regression.

commit 811230cd85 ("tcp: ipv4: initialize unicast_sock sk_pacing_rate")
was another shot in the dark.

Really, just use a proper socket per cpu, and remove the skb_orphan()
call, to re-enable flow control.

This solves a serious problem with FQ packet scheduler when used in
hostile environments, as we do not want to allocate a flow structure
for every RST packet sent in response to a spoofed packet.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: try to cache dst_entries which would cause a redirect

2015-02-27T01:50:10+00:00

[ Upstream commit df4d92549f23e1c037e83323aff58a21b3de7fe0 ]

Not caching dst_entries which cause redirects could be exploited by hosts
on the same subnet, causing a severe DoS attack. This effect aggravated
since commit f88649721268999 ("ipv4: fix dst race in sk_dst_get()").

Lookups causing redirects will be allocated with DST_NOCACHE set which
will force dst_release to free them via RCU.  Unfortunately waiting for
RCU grace period just takes too long, we can end up with >1M dst_entries
waiting to be released and the system will run OOM. rcuos threads cannot
catch up under high softirq load.

Attaching the flag to emit a redirect later on to the specific skb allows
us to cache those dst_entries thus reducing the pressure on allocation
and deallocation.

This issue was discovered by Marcelo Leitner.

Cc: Julian Anastasov 
Signed-off-by: Marcelo Leitner 
Signed-off-by: Florian Westphal 
Signed-off-by: Hannes Frederic Sowa 
Signed-off-by: Julian Anastasov 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: sctp: fix skb_over_panic when receiving malformed ASCONF chunks

2014-11-21T17:23:06+00:00

commit 9de7922bc709eee2f609cd01d98aaedc4cf5ea74 upstream.

Commit 6f4c618ddb0 ("SCTP : Add paramters validity check for
ASCONF chunk") added basic verification of ASCONF chunks, however,
it is still possible to remotely crash a server by sending a
special crafted ASCONF chunk, even up to pre 2.6.12 kernels:

skb_over_panic: text:ffffffffa01ea1c3 len:31056 put:30768
 head:ffff88011bd81800 data:ffff88011bd81800 tail:0x7950
 end:0x440 dev:
 ------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:129!
[...]
Call Trace:
 
 [] skb_put+0x5c/0x70
 [] sctp_addto_chunk+0x63/0xd0 [sctp]
 [] sctp_process_asconf+0x1af/0x540 [sctp]
 [] ? _read_unlock_bh+0x15/0x20
 [] sctp_sf_do_asconf+0x168/0x240 [sctp]
 [] sctp_do_sm+0x71/0x1210 [sctp]
 [] ? fib_rules_lookup+0xad/0xf0
 [] ? sctp_cmp_addr_exact+0x32/0x40 [sctp]
 [] sctp_assoc_bh_rcv+0xd3/0x180 [sctp]
 [] sctp_inq_push+0x56/0x80 [sctp]
 [] sctp_rcv+0x982/0xa10 [sctp]
 [] ? ipt_local_in_hook+0x23/0x28 [iptable_filter]
 [] ? nf_iterate+0x69/0xb0
 [] ? ip_local_deliver_finish+0x0/0x2d0
 [] ? nf_hook_slow+0x76/0x120
 [] ? ip_local_deliver_finish+0x0/0x2d0
 [] ip_local_deliver_finish+0xdd/0x2d0
 [] ip_local_deliver+0x98/0xa0
 [] ip_rcv_finish+0x12d/0x440
 [] ip_rcv+0x275/0x350
 [] __netif_receive_skb+0x4ab/0x750
 [] netif_receive_skb+0x58/0x60

This can be triggered e.g., through a simple scripted nmap
connection scan injecting the chunk after the handshake, for
example, ...

  -------------- INIT[ASCONF; ASCONF_ACK] ------------->
  <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
  -------------------- COOKIE-ECHO -------------------->
  <-------------------- COOKIE-ACK ---------------------
  ------------------ ASCONF; UNKNOWN ------------------>

... where ASCONF chunk of length 280 contains 2 parameters ...

  1) Add IP address parameter (param length: 16)
  2) Add/del IP address parameter (param length: 255)

... followed by an UNKNOWN chunk of e.g. 4 bytes. Here, the
Address Parameter in the ASCONF chunk is even missing, too.
This is just an example and similarly-crafted ASCONF chunks
could be used just as well.

The ASCONF chunk passes through sctp_verify_asconf() as all
parameters passed sanity checks, and after walking, we ended
up successfully at the chunk end boundary, and thus may invoke
sctp_process_asconf(). Parameter walking is done with
WORD_ROUND() to take padding into account.

In sctp_process_asconf()'s TLV processing, we may fail in
sctp_process_asconf_param() e.g., due to removal of the IP
address that is also the source address of the packet containing
the ASCONF chunk, and thus we need to add all TLVs after the
failure to our ASCONF response to remote via helper function
sctp_add_asconf_response(), which basically invokes a
sctp_addto_chunk() adding the error parameters to the given
skb.

When walking to the next parameter this time, we proceed
with ...

  length = ntohs(asconf_param->param_hdr.length);
  asconf_param = (void *)asconf_param + length;

... instead of the WORD_ROUND()'ed length, thus resulting here
in an off-by-one that leads to reading the follow-up garbage
parameter length of 12336, and thus throwing an skb_over_panic
for the reply when trying to sctp_addto_chunk() next time,
which implicitly calls the skb_put() with that length.

Fix it by using sctp_walk_params() [ which is also used in
INIT parameter processing ] macro in the verification *and*
in ASCONF processing: it will make sure we don't spill over,
that we walk parameters WORD_ROUND()'ed. Moreover, we're being
more defensive and guard against unknown parameter types and
missized addresses.

Joint work with Vlad Yasevich.

Fixes: b896b82be4ae ("[SCTP] ADDIP: Support for processing incoming ASCONF_ACK chunks.")
Signed-off-by: Daniel Borkmann 
Signed-off-by: Vlad Yasevich 
Acked-by: Neil Horman 
Signed-off-by: David S. Miller 
Cc: Josh Boyer 
Signed-off-by: Greg Kroah-Hartman

net: sctp: fix panic on duplicate ASCONF chunks

2014-11-21T17:23:05+00:00

commit b69040d8e39f20d5215a03502a8e8b4c6ab78395 upstream.

When receiving a e.g. semi-good formed connection scan in the
form of ...

  -------------- INIT[ASCONF; ASCONF_ACK] ------------->
  <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
  -------------------- COOKIE-ECHO -------------------->
  <-------------------- COOKIE-ACK ---------------------
  ---------------- ASCONF_a; ASCONF_b ----------------->

... where ASCONF_a equals ASCONF_b chunk (at least both serials
need to be equal), we panic an SCTP server!

The problem is that good-formed ASCONF chunks that we reply with
ASCONF_ACK chunks are cached per serial. Thus, when we receive a
same ASCONF chunk twice (e.g. through a lost ASCONF_ACK), we do
not need to process them again on the server side (that was the
idea, also proposed in the RFC). Instead, we know it was cached
and we just resend the cached chunk instead. So far, so good.

Where things get nasty is in SCTP's side effect interpreter, that
is, sctp_cmd_interpreter():

While incoming ASCONF_a (chunk = event_arg) is being marked
!end_of_packet and !singleton, and we have an association context,
we do not flush the outqueue the first time after processing the
ASCONF_ACK singleton chunk via SCTP_CMD_REPLY. Instead, we keep it
queued up, although we set local_cork to 1. Commit 2e3216cd54b1
changed the precedence, so that as long as we get bundled, incoming
chunks we try possible bundling on outgoing queue as well. Before
this commit, we would just flush the output queue.

Now, while ASCONF_a's ASCONF_ACK sits in the corked outq, we
continue to process the same ASCONF_b chunk from the packet. As
we have cached the previous ASCONF_ACK, we find it, grab it and
do another SCTP_CMD_REPLY command on it. So, effectively, we rip
the chunk->list pointers and requeue the same ASCONF_ACK chunk
another time. Since we process ASCONF_b, it's correctly marked
with end_of_packet and we enforce an uncork, and thus flush, thus
crashing the kernel.

Fix it by testing if the ASCONF_ACK is currently pending and if
that is the case, do not requeue it. When flushing the output
queue we may relink the chunk for preparing an outgoing packet,
but eventually unlink it when it's copied into the skb right
before transmission.

Joint work with Vlad Yasevich.

Fixes: 2e3216cd54b1 ("sctp: Follow security requirement of responding with 1 packet")
Signed-off-by: Daniel Borkmann 
Signed-off-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Cc: Josh Boyer 
Signed-off-by: Greg Kroah-Hartman

drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO packets

2014-11-14T16:59:44+00:00

[ Upstream commit 5188cd44c55db3e92cd9e77a40b5baa7ed4340f7 ]

UFO is now disabled on all drivers that work with virtio net headers,
but userland may try to send UFO/IPv6 packets anyway.  Instead of
sending with ID=0, we should select identifiers on their behalf (as we
used to).

Signed-off-by: Ben Hutchings 
Fixes: 916e4cf46d02 ("ipv6: reuse ip6_frag_id from ip6_ufo_append_data")
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

sctp: handle association restarts when the socket is closed.

2014-10-15T06:36:42+00:00

[ Upstream commit bdf6fa52f01b941d4a80372d56de465bdbbd1d23 ]

Currently association restarts do not take into consideration the
state of the socket.  When a restart happens, the current assocation
simply transitions into established state.  This creates a condition
where a remote system, through a the restart procedure, may create a
local association that is no way reachable by user.  The conditions
to trigger this are as follows:
  1) Remote does not acknoledge some data causing data to remain
     outstanding.
  2) Local application calls close() on the socket.  Since data
     is still outstanding, the association is placed in SHUTDOWN_PENDING
     state.  However, the socket is closed.
  3) The remote tries to create a new association, triggering a restart
     on the local system.  The association moves from SHUTDOWN_PENDING
     to ESTABLISHED.  At this point, it is no longer reachable by
     any socket on the local system.

This patch addresses the above situation by moving the newly ESTABLISHED
association into SHUTDOWN-SENT state and bundling a SHUTDOWN after
the COOKIE-ACK chunk.  This way, the restarted associate immidiately
enters the shutdown procedure and forces the termination of the
unreachable association.

Reported-by: David Laight 
Signed-off-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

xfrm: Generate queueing routes only from route lookup functions

2014-10-15T06:36:42+00:00

[ Upstream commit b8c203b2d2fc961bafd53b41d5396bbcdec55998 ]

Currently we genarate a queueing route if we have matching policies
but can not resolve the states and the sysctl xfrm_larval_drop is
disabled. Here we assume that dst_output() is called to kill the
queued packets. Unfortunately this assumption is not true in all
cases, so it is possible that these packets leave the system unwanted.

We fix this by generating queueing routes only from the
route lookup functions, here we can guarantee a call to
dst_output() afterwards.

Fixes: a0073fe18e71 ("xfrm: Add a state resolution packet queue")
Reported-by: Konstantinos Kolelis 
Signed-off-by: Steffen Klassert 
Signed-off-by: Greg Kroah-Hartman

xfrm: Generate blackhole routes only from route lookup functions

2014-10-15T06:36:42+00:00

[ Upstream commit f92ee61982d6da15a9e49664ecd6405a15a2ee56 ]

Currently we genarate a blackhole route route whenever we have
matching policies but can not resolve the states. Here we assume
that dst_output() is called to kill the balckholed packets.
Unfortunately this assumption is not true in all cases, so
it is possible that these packets leave the system unwanted.

We fix this by generating blackhole routes only from the
route lookup functions, here we can guarantee a call to
dst_output() afterwards.

Fixes: 2774c131b1d ("xfrm: Handle blackhole route creation via afinfo.")
Reported-by: Konstantinos Kolelis 
Signed-off-by: Steffen Klassert 
Signed-off-by: Greg Kroah-Hartman

tcp: fix tcp_release_cb() to dispatch via address family for mtu_reduced()

2014-10-15T06:36:40+00:00

[ Upstream commit 4fab9071950c2021d846e18351e0f46a1cffd67b ]

Make sure we use the correct address-family-specific function for
handling MTU reductions from within tcp_release_cb().

Previously AF_INET6 sockets were incorrectly always using the IPv6
code path when sometimes they were handling IPv4 traffic and thus had
an IPv4 dst.

Signed-off-by: Neal Cardwell 
Signed-off-by: Eric Dumazet 
Diagnosed-by: Willem de Bruijn 
Fixes: 563d34d057862 ("tcp: dont drop MTU reduction indications")
Reviewed-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman