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Diffstat (limited to 'recipes-kernel/linux/files/net-sctp-CVE-2014-0101.patch')
| -rw-r--r-- | recipes-kernel/linux/files/net-sctp-CVE-2014-0101.patch | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/recipes-kernel/linux/files/net-sctp-CVE-2014-0101.patch b/recipes-kernel/linux/files/net-sctp-CVE-2014-0101.patch new file mode 100644 index 00000000..ddcb6c5d --- /dev/null +++ b/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 +@@ -768,6 +768,13 @@ sctp_disposition_t sctp_sf_do_5_1D_ce(struct net *net, + return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); + } + ++ /* 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 + |