net-sctp: CVE-2014-0101

Fixes null pointer dereference when processing authenticated cookie_echo chunk

Reference:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0101
https://bugzilla.redhat.com/show_bug.cgi?id=1070705

Introduced by:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bbd0d59809f9

Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>

2 files changed, 146 insertions, 0 deletions

diff --git a/meta-fsl-ppc/recipes-kernel/linux/files/net-sctp-CVE-2014-0101.patch b/meta-fsl-ppc/recipes-kernel/linux/files/net-sctp-CVE-2014-0101.patch
new file mode 100644
index 00000000..6fc5610e
--- /dev/null
+++ b/meta-fsl-ppc/recipes-kernel/linux/files/net-sctp-CVE-2014-0101.patch
@@ -0,0 +1,145 @@
+From 00c53b02cb01976b35d37670a4b5c5d7a6ad3c62 Mon Sep 17 00:00:00 2001
+From: Daniel Borkmann <dborkman@redhat.com>
+Date: Mon, 3 Mar 2014 17:23:04 +0100
+Subject: [PATCH] net: sctp: fix sctp_sf_do_5_1D_ce to verify if we/peer is
+ AUTH capable
+
+[ 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.
+
+This fixes CVE-2014-0101
+Upstream-Status: Backport
+
+Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk")
+Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
+Cc: Vlad Yasevich <yasevich@gmail.com>
+Cc: Neil Horman <nhorman@tuxdriver.com>
+Acked-by: Vlad Yasevich <vyasevich@gmail.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+ net/sctp/sm_statefuns.c | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
+index dfe3f36..56ebe71 100644
+--- a/net/sctp/sm_statefuns.c
++++ b/net/sctp/sm_statefuns.c
+@@ -759,6 +759,13 @@ sctp_disposition_t sctp_sf_do_5_1D_ce(struct net *net,
+                struct sctp_chunk auth;
+                sctp_ierror_t ret;
+ 
++               /* Make sure that we and the peer are AUTH capable */
++               if (!net->sctp.auth_enable || !new_asoc->peer.auth_capable) {
++                       kfree_skb(chunk->auth_chunk);
++                       sctp_association_free(new_asoc);
++                       return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
++               }
++
+                /* set-up our fake chunk so that we can process it */
+                auth.skb = chunk->auth_chunk;
+                auth.asoc = chunk->asoc;
+-- 
+1.9.1
+
diff --git a/meta-fsl-ppc/recipes-kernel/linux/linux-qoriq_3.12.bb b/meta-fsl-ppc/recipes-kernel/linux/linux-qoriq_3.12.bb
index 48a67c0d..874a3f2b 100644
--- a/meta-fsl-ppc/recipes-kernel/linux/linux-qoriq_3.12.bb
+++ b/meta-fsl-ppc/recipes-kernel/linux/linux-qoriq_3.12.bb
@@ -12,6 +12,7 @@ SRC_URI = "git://git.freescale.com/ppc/sdk/linux.git;nobranch=1 \
     file://0004-mnt-CVE-2014-5206_CVE-2014-5207.patch \
     file://0005-mnt-CVE-2014-5206_CVE-2014-5207.patch \
     file://udf-CVE-2014-6410.patch \
+    file://net-sctp-CVE-2014-0101.patch \
 "
 SRCREV = "6619b8b55796cdf0cec04b66a71288edd3057229"