linux-toradex.git/net/sctp, branch v3.4.87

net: sctp: fix sctp_sf_do_5_1D_ce to verify if we/peer is AUTH capable

2014-03-24T04:37:04+00:00

[ Upstream commit ec0223ec48a90cb605244b45f7c62de856403729 ]

RFC4895 introduced AUTH chunks for SCTP; during the SCTP
handshake RANDOM; CHUNKS; HMAC-ALGO are negotiated (CHUNKS
being optional though):

  ---------- INIT[RANDOM; CHUNKS; HMAC-ALGO] ---------->
  <------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] ---------
  -------------------- COOKIE-ECHO -------------------->
  <-------------------- COOKIE-ACK ---------------------

A special case is when an endpoint requires COOKIE-ECHO
chunks to be authenticated:

  ---------- INIT[RANDOM; CHUNKS; HMAC-ALGO] ---------->
  <------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] ---------
  ------------------ AUTH; COOKIE-ECHO ---------------->
  <-------------------- COOKIE-ACK ---------------------

RFC4895, section 6.3. Receiving Authenticated Chunks says:

  The receiver MUST use the HMAC algorithm indicated in
  the HMAC Identifier field. If this algorithm was not
  specified by the receiver in the HMAC-ALGO parameter in
  the INIT or INIT-ACK chunk during association setup, the
  AUTH chunk and all the chunks after it MUST be discarded
  and an ERROR chunk SHOULD be sent with the error cause
  defined in Section 4.1. [...] If no endpoint pair shared
  key has been configured for that Shared Key Identifier,
  all authenticated chunks MUST be silently discarded. [...]

  When an endpoint requires COOKIE-ECHO chunks to be
  authenticated, some special procedures have to be followed
  because the reception of a COOKIE-ECHO chunk might result
  in the creation of an SCTP association. If a packet arrives
  containing an AUTH chunk as a first chunk, a COOKIE-ECHO
  chunk as the second chunk, and possibly more chunks after
  them, and the receiver does not have an STCB for that
  packet, then authentication is based on the contents of
  the COOKIE-ECHO chunk. In this situation, the receiver MUST
  authenticate the chunks in the packet by using the RANDOM
  parameters, CHUNKS parameters and HMAC_ALGO parameters
  obtained from the COOKIE-ECHO chunk, and possibly a local
  shared secret as inputs to the authentication procedure
  specified in Section 6.3. If authentication fails, then
  the packet is discarded. If the authentication is successful,
  the COOKIE-ECHO and all the chunks after the COOKIE-ECHO
  MUST be processed. If the receiver has an STCB, it MUST
  process the AUTH chunk as described above using the STCB
  from the existing association to authenticate the
  COOKIE-ECHO chunk and all the chunks after it. [...]

Commit bbd0d59809f9 introduced the possibility to receive
and verification of AUTH chunk, including the edge case for
authenticated COOKIE-ECHO. On reception of COOKIE-ECHO,
the function sctp_sf_do_5_1D_ce() handles processing,
unpacks and creates a new association if it passed sanity
checks and also tests for authentication chunks being
present. After a new association has been processed, it
invokes sctp_process_init() on the new association and
walks through the parameter list it received from the INIT
chunk. It checks SCTP_PARAM_RANDOM, SCTP_PARAM_HMAC_ALGO
and SCTP_PARAM_CHUNKS, and copies them into asoc->peer
meta data (peer_random, peer_hmacs, peer_chunks) in case
sysctl -w net.sctp.auth_enable=1 is set. If in INIT's
SCTP_PARAM_SUPPORTED_EXT parameter SCTP_CID_AUTH is set,
peer_random != NULL and peer_hmacs != NULL the peer is to be
assumed asoc->peer.auth_capable=1, in any other case
asoc->peer.auth_capable=0.

Now, if in sctp_sf_do_5_1D_ce() chunk->auth_chunk is
available, we set up a fake auth chunk and pass that on to
sctp_sf_authenticate(), which at latest in
sctp_auth_calculate_hmac() reliably dereferences a NULL pointer
at position 0..0008 when setting up the crypto key in
crypto_hash_setkey() by using asoc->asoc_shared_key that is
NULL as condition key_id == asoc->active_key_id is true if
the AUTH chunk was injected correctly from remote. This
happens no matter what net.sctp.auth_enable sysctl says.

The fix is to check for net->sctp.auth_enable and for
asoc->peer.auth_capable before doing any operations like
sctp_sf_authenticate() as no key is activated in
sctp_auth_asoc_init_active_key() for each case.

Now as RFC4895 section 6.3 states that if the used HMAC-ALGO
passed from the INIT chunk was not used in the AUTH chunk, we
SHOULD send an error; however in this case it would be better
to just silently discard such a maliciously prepared handshake
as we didn't even receive a parameter at all. Also, as our
endpoint has no shared key configured, section 6.3 says that
MUST silently discard, which we are doing from now onwards.

Before calling sctp_sf_pdiscard(), we need not only to free
the association, but also the chunk->auth_chunk skb, as
commit bbd0d59809f9 created a skb clone in that case.

I have tested this locally by using netfilter's nfqueue and
re-injecting packets into the local stack after maliciously
modifying the INIT chunk (removing RANDOM; HMAC-ALGO param)
and the SCTP packet containing the COOKIE_ECHO (injecting
AUTH chunk before COOKIE_ECHO). Fixed with this patch applied.

Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk")
Signed-off-by: Daniel Borkmann 
Cc: Vlad Yasevich 
Cc: Neil Horman 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: sctp: fix sctp_connectx abi for ia32 emulation/compat mode

2014-03-11T23:09:59+00:00

[ Upstream commit ffd5939381c609056b33b7585fb05a77b4c695f3 ]

SCTP's sctp_connectx() abi breaks for 64bit kernels compiled with 32bit
emulation (e.g. ia32 emulation or x86_x32). Due to internal usage of
'struct sctp_getaddrs_old' which includes a struct sockaddr pointer,
sizeof(param) check will always fail in kernel as the structure in
64bit kernel space is 4bytes larger than for user binaries compiled
in 32bit mode. Thus, applications making use of sctp_connectx() won't
be able to run under such circumstances.

Introduce a compat interface in the kernel to deal with such
situations by using a 'struct compat_sctp_getaddrs_old' structure
where user data is copied into it, and then sucessively transformed
into a 'struct sctp_getaddrs_old' structure with the help of
compat_ptr(). That fixes sctp_connectx() abi without any changes
needed in user space, and lets the SCTP test suite pass when compiled
in 32bit and run on 64bit kernels.

Fixes: f9c67811ebc0 ("sctp: Fix regression introduced by new sctp_connectx api")
Signed-off-by: Daniel Borkmann 
Acked-by: Neil Horman 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

sctp: Perform software checksum if packet has to be fragmented.

2013-11-04T12:23:41+00:00

[ Upstream commit d2dbbba77e95dff4b4f901fee236fef6d9552072 ]

IP/IPv6 fragmentation knows how to compute only TCP/UDP checksum.
This causes problems if SCTP packets has to be fragmented and
ipsummed has been set to PARTIAL due to checksum offload support.
This condition can happen when retransmitting after MTU discover,
or when INIT or other control chunks are larger then MTU.
Check for the rare fragmentation condition in SCTP and use software
checksum calculation in this case.

CC: Fan Du 
Signed-off-by: Vlad Yasevich 
Acked-by: Neil Horman 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

sctp: Use software crc32 checksum when xfrm transform will happen.

2013-11-04T12:23:41+00:00

[ Upstream commit 27127a82561a2a3ed955ce207048e1b066a80a2a ]

igb/ixgbe have hardware sctp checksum support, when this feature is enabled
and also IPsec is armed to protect sctp traffic, ugly things happened as
xfrm_output checks CHECKSUM_PARTIAL to do checksum operation(sum every thing
up and pack the 16bits result in the checksum field). The result is fail
establishment of sctp communication.

Signed-off-by: Fan Du 
Cc: Neil Horman 
Cc: Steffen Klassert 
Signed-off-by: Vlad Yasevich 
Acked-by: Neil Horman 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: sctp: fix ipv6 ipsec encryption bug in sctp_v6_xmit

2013-10-13T22:42:47+00:00

[ Upstream commit 95ee62083cb6453e056562d91f597552021e6ae7 ]

Alan Chester reported an issue with IPv6 on SCTP that IPsec traffic is not
being encrypted, whereas on IPv4 it is. Setting up an AH + ESP transport
does not seem to have the desired effect:

SCTP + IPv4:

  22:14:20.809645 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto AH (51), length 116)
    192.168.0.2 > 192.168.0.5: AH(spi=0x00000042,sumlen=16,seq=0x1): ESP(spi=0x00000044,seq=0x1), length 72
  22:14:20.813270 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto AH (51), length 340)
    192.168.0.5 > 192.168.0.2: AH(spi=0x00000043,sumlen=16,seq=0x1):

SCTP + IPv6:

  22:31:19.215029 IP6 (class 0x02, hlim 64, next-header SCTP (132) payload length: 364)
    fe80::222:15ff:fe87:7fc.3333 > fe80::92e6:baff:fe0d:5a54.36767: sctp
    1) [INIT ACK] [init tag: 747759530] [rwnd: 62464] [OS: 10] [MIS: 10]

Moreover, Alan says:

  This problem was seen with both Racoon and Racoon2. Other people have seen
  this with OpenSwan. When IPsec is configured to encrypt all upper layer
  protocols the SCTP connection does not initialize. After using Wireshark to
  follow packets, this is because the SCTP packet leaves Box A unencrypted and
  Box B believes all upper layer protocols are to be encrypted so it drops
  this packet, causing the SCTP connection to fail to initialize. When IPsec
  is configured to encrypt just SCTP, the SCTP packets are observed unencrypted.

In fact, using `socat sctp6-listen:3333 -` on one end and transferring "plaintext"
string on the other end, results in cleartext on the wire where SCTP eventually
does not report any errors, thus in the latter case that Alan reports, the
non-paranoid user might think he's communicating over an encrypted transport on
SCTP although he's not (tcpdump ... -X):

  ...
  0x0030: 5d70 8e1a 0003 001a 177d eb6c 0000 0000  ]p.......}.l....
  0x0040: 0000 0000 706c 6169 6e74 6578 740a 0000  ....plaintext...

Only in /proc/net/xfrm_stat we can see XfrmInTmplMismatch increasing on the
receiver side. Initial follow-up analysis from Alan's bug report was done by
Alexey Dobriyan. Also thanks to Vlad Yasevich for feedback on this.

SCTP has its own implementation of sctp_v6_xmit() not calling inet6_csk_xmit().
This has the implication that it probably never really got updated along with
changes in inet6_csk_xmit() and therefore does not seem to invoke xfrm handlers.

SCTP's IPv4 xmit however, properly calls ip_queue_xmit() to do the work. Since
a call to inet6_csk_xmit() would solve this problem, but result in unecessary
route lookups, let us just use the cached flowi6 instead that we got through
sctp_v6_get_dst(). Since all SCTP packets are being sent through sctp_packet_transmit(),
we do the route lookup / flow caching in sctp_transport_route(), hold it in
tp->dst and skb_dst_set() right after that. If we would alter fl6->daddr in
sctp_v6_xmit() to np->opt->srcrt, we possibly could run into the same effect
of not having xfrm layer pick it up, hence, use fl6_update_dst() in sctp_v6_get_dst()
instead to get the correct source routed dst entry, which we assign to the skb.

Also source address routing example from 625034113 ("sctp: fix sctp to work with
ipv6 source address routing") still works with this patch! Nevertheless, in RFC5095
it is actually 'recommended' to not use that anyway due to traffic amplification [1].
So it seems we're not supposed to do that anyway in sctp_v6_xmit(). Moreover, if
we overwrite the flow destination here, the lower IPv6 layer will be unable to
put the correct destination address into IP header, as routing header is added in
ipv6_push_nfrag_opts() but then probably with wrong final destination. Things aside,
result of this patch is that we do not have any XfrmInTmplMismatch increase plus on
the wire with this patch it now looks like:

SCTP + IPv6:

  08:17:47.074080 IP6 2620:52:0:102f:7a2b:cbff:fe27:1b0a > 2620:52:0:102f:213:72ff:fe32:7eba:
    AH(spi=0x00005fb4,seq=0x1): ESP(spi=0x00005fb5,seq=0x1), length 72
  08:17:47.074264 IP6 2620:52:0:102f:213:72ff:fe32:7eba > 2620:52:0:102f:7a2b:cbff:fe27:1b0a:
    AH(spi=0x00003d54,seq=0x1): ESP(spi=0x00003d55,seq=0x1), length 296

This fixes Kernel Bugzilla 24412. This security issue seems to be present since
2.6.18 kernels. Lets just hope some big passive adversary in the wild didn't have
its fun with that. lksctp-tools IPv6 regression test suite passes as well with
this patch.

 [1] http://www.secdev.org/conf/IPv6_RH_security-csw07.pdf

Reported-by: Alan Chester 
Reported-by: Alexey Dobriyan 
Signed-off-by: Daniel Borkmann 
Cc: Steffen Klassert 
Cc: Hannes Frederic Sowa 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: sctp: fix smatch warning in sctp_send_asconf_del_ip

2013-10-13T22:42:47+00:00

[ Upstream commit 88362ad8f9a6cea787420b57cc27ccacef000dbe ]

This was originally reported in [1] and posted by Neil Horman [2], he said:

  Fix up a missed null pointer check in the asconf code. If we don't find
  a local address, but we pass in an address length of more than 1, we may
  dereference a NULL laddr pointer. Currently this can't happen, as the only
  users of the function pass in the value 1 as the addrcnt parameter, but
  its not hot path, and it doesn't hurt to check for NULL should that ever
  be the case.

The callpath from sctp_asconf_mgmt() looks okay. But this could be triggered
from sctp_setsockopt_bindx() call with SCTP_BINDX_REM_ADDR and addrcnt > 1
while passing all possible addresses from the bind list to SCTP_BINDX_REM_ADDR
so that we do *not* find a single address in the association's bind address
list that is not in the packed array of addresses. If this happens when we
have an established association with ASCONF-capable peers, then we could get
a NULL pointer dereference as we only check for laddr == NULL && addrcnt == 1
and call later sctp_make_asconf_update_ip() with NULL laddr.

BUT: this actually won't happen as sctp_bindx_rem() will catch such a case
and return with an error earlier. As this is incredably unintuitive and error
prone, add a check to catch at least future bugs here. As Neil says, its not
hot path. Introduced by 8a07eb0a5 ("sctp: Add ASCONF operation on the
single-homed host").

 [1] http://www.spinics.net/lists/linux-sctp/msg02132.html
 [2] http://www.spinics.net/lists/linux-sctp/msg02133.html

Reported-by: Dan Carpenter 
Signed-off-by: Neil Horman 
Signed-off-by: Daniel Borkmann 
Cc: Michio Honda 
Acked-By: Neil Horman 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

Revert "sctp: fix call to SCTP_CMD_PROCESS_SACK in sctp_cmd_interpreter()"

2013-10-01T16:10:50+00:00

This reverts commit c2f5b7507ac5d808f29287d77ee6148358d7fbfe which is
commit f6e80abeab928b7c47cc1fbf53df13b4398a2bec.

Michal writes:
	Mainline commit f6e80abe was introduced in v3.7-rc2 as a
	follow-up fix to commit

	  edfee033  sctp: check src addr when processing SACK to update transport state

	(from v3.7-rc1) which changed the interpretation of third
	argument to sctp_cmd_process_sack() and sctp_outq_sack(). But as
	commit edfee033 has never been backported to stable branches,
	backport of commit f6e80abe actually breaks the code rather than
	fixing it.

Reported-by: Michal Kubecek 
Cc: Zijie Pan 
Cc: Nicolas Dichtel 
Cc: Vlad Yasevich 
Acked-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

sctp: fully initialize sctp_outq in sctp_outq_init

2013-08-11T22:38:44+00:00

[ Upstream commit c5c7774d7eb4397891edca9ebdf750ba90977a69 ]

In commit 2f94aabd9f6c925d77aecb3ff020f1cc12ed8f86
(refactor sctp_outq_teardown to insure proper re-initalization)
we modified sctp_outq_teardown to use sctp_outq_init to fully re-initalize the
outq structure.  Steve West recently asked me why I removed the q->error = 0
initalization from sctp_outq_teardown.  I did so because I was operating under
the impression that sctp_outq_init would properly initalize that value for us,
but it doesn't.  sctp_outq_init operates under the assumption that the outq
struct is all 0's (as it is when called from sctp_association_init), but using
it in __sctp_outq_teardown violates that assumption. We should do a memset in
sctp_outq_init to ensure that the entire structure is in a known state there
instead.

Signed-off-by: Neil Horman 
Reported-by: "West, Steve (NSN - US/Fort Worth)" 
CC: Vlad Yasevich 
CC: netdev@vger.kernel.org
CC: davem@davemloft.net
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: sctp: fix NULL pointer dereference in socket destruction

2013-06-27T18:27:32+00:00

[ Upstream commit 1abd165ed757db1afdefaac0a4bc8a70f97d258c ]

While stress testing sctp sockets, I hit the following panic:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
IP: [] sctp_endpoint_free+0xe/0x40 [sctp]
PGD 7cead067 PUD 7ce76067 PMD 0
Oops: 0000 [#1] SMP
Modules linked in: sctp(F) libcrc32c(F) [...]
CPU: 7 PID: 2950 Comm: acc Tainted: GF            3.10.0-rc2+ #1
Hardware name: Dell Inc. PowerEdge T410/0H19HD, BIOS 1.6.3 02/01/2011
task: ffff88007ce0e0c0 ti: ffff88007b568000 task.ti: ffff88007b568000
RIP: 0010:[]  [] sctp_endpoint_free+0xe/0x40 [sctp]
RSP: 0018:ffff88007b569e08  EFLAGS: 00010292
RAX: 0000000000000000 RBX: ffff88007db78a00 RCX: dead000000200200
RDX: ffffffffa049fdb0 RSI: ffff8800379baf38 RDI: 0000000000000000
RBP: ffff88007b569e18 R08: ffff88007c230da0 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff880077990d00 R14: 0000000000000084 R15: ffff88007db78a00
FS:  00007fc18ab61700(0000) GS:ffff88007fc60000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000020 CR3: 000000007cf9d000 CR4: 00000000000007e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
 ffff88007b569e38 ffff88007db78a00 ffff88007b569e38 ffffffffa049fded
 ffffffff81abf0c0 ffff88007db78a00 ffff88007b569e58 ffffffff8145b60e
 0000000000000000 0000000000000000 ffff88007b569eb8 ffffffff814df36e
Call Trace:
 [] sctp_destroy_sock+0x3d/0x80 [sctp]
 [] sk_common_release+0x1e/0xf0
 [] inet_create+0x2ae/0x350
 [] __sock_create+0x11f/0x240
 [] sock_create+0x30/0x40
 [] SyS_socket+0x4c/0xc0
 [] ? do_page_fault+0xe/0x10
 [] ? page_fault+0x22/0x30
 [] system_call_fastpath+0x16/0x1b
Code: 0c c9 c3 66 2e 0f 1f 84 00 00 00 00 00 e8 fb fe ff ff c9 c3 66 0f
      1f 84 00 00 00 00 00 55 48 89 e5 53 48 83 ec 08 66 66 66 66 90 <48>
      8b 47 20 48 89 fb c6 47 1c 01 c6 40 12 07 e8 9e 68 01 00 48
RIP  [] sctp_endpoint_free+0xe/0x40 [sctp]
 RSP 
CR2: 0000000000000020
---[ end trace e0d71ec1108c1dd9 ]---

I did not hit this with the lksctp-tools functional tests, but with a
small, multi-threaded test program, that heavily allocates, binds,
listens and waits in accept on sctp sockets, and then randomly kills
some of them (no need for an actual client in this case to hit this).
Then, again, allocating, binding, etc, and then killing child processes.

This panic then only occurs when ``echo 1 > /proc/sys/net/sctp/auth_enable''
is set. The cause for that is actually very simple: in sctp_endpoint_init()
we enter the path of sctp_auth_init_hmacs(). There, we try to allocate
our crypto transforms through crypto_alloc_hash(). In our scenario,
it then can happen that crypto_alloc_hash() fails with -EINTR from
crypto_larval_wait(), thus we bail out and release the socket via
sk_common_release(), sctp_destroy_sock() and hit the NULL pointer
dereference as soon as we try to access members in the endpoint during
sctp_endpoint_free(), since endpoint at that time is still NULL. Now,
if we have that case, we do not need to do any cleanup work and just
leave the destruction handler.

Signed-off-by: Daniel Borkmann 
Acked-by: Neil Horman 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: sctp: sctp_auth_key_put: use kzfree instead of kfree

2013-05-01T16:41:08+00:00

[ Upstream commit 586c31f3bf04c290dc0a0de7fc91d20aa9a5ee53 ]

For sensitive data like keying material, it is common practice to zero
out keys before returning the memory back to the allocator. Thus, use
kzfree instead of kfree.

Signed-off-by: Daniel Borkmann 
Acked-by: Neil Horman 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman