From 5b6256afd7b5e4ea094b583a9a6a5aab6b2f1ec3 Mon Sep 17 00:00:00 2001 From: Josh Boyer Date: Fri, 13 Sep 2013 11:16:43 -0400 Subject: CVE-2013-XXXX net: sctp: ipv6 ipsec encryption bug in sctp_v6_xmit (rhbz 1007872 1007903) --- kernel.spec | 7 + ...ipv6-ipsec-encryption-bug-in-sctp_v6_xmit.patch | 186 +++++++++++++++++++++ 2 files changed, 193 insertions(+) create mode 100644 net-sctp-fix-ipv6-ipsec-encryption-bug-in-sctp_v6_xmit.patch diff --git a/kernel.spec b/kernel.spec index 45a2ede29..557c81e67 100644 --- a/kernel.spec +++ b/kernel.spec @@ -764,6 +764,9 @@ Patch25099: HID-CVE-fixes.patch #CVE-2013-4343 rhbz 1007733 1007741 Patch25100: tuntap-correctly-handle-error-in-tun_set_iff.patch +#CVE-2013-XXXX rhbz 1007872 1007903 +Patch25102: net-sctp-fix-ipv6-ipsec-encryption-bug-in-sctp_v6_xmit.patch + Patch25101: fix-arm-neon-xor.patch # END OF PATCH DEFINITIONS @@ -1492,6 +1495,9 @@ ApplyPatch fix-arm-neon-xor.patch #CVE-2013-4343 rhbz 1007733 1007741 ApplyPatch tuntap-correctly-handle-error-in-tun_set_iff.patch +#CVE-2013-XXXX rhbz 1007872 1007903 +ApplyPatch net-sctp-fix-ipv6-ipsec-encryption-bug-in-sctp_v6_xmit.patch + # END OF PATCH APPLICATIONS %endif @@ -2294,6 +2300,7 @@ fi # || || %changelog * Fri Sep 13 2013 Josh Boyer +- CVE-2013-XXXX net: sctp: ipv6 ipsec encryption bug in sctp_v6_xmit (rhbz 1007872 1007903) - CVE-2013-4343 net: use-after-free TUNSETIFF (rhbz 1007733 1007741) * Thu Sep 12 2013 Josh Boyer - 3.12.0-0.rc0.git23.1 diff --git a/net-sctp-fix-ipv6-ipsec-encryption-bug-in-sctp_v6_xmit.patch b/net-sctp-fix-ipv6-ipsec-encryption-bug-in-sctp_v6_xmit.patch new file mode 100644 index 000000000..671ee98db --- /dev/null +++ b/net-sctp-fix-ipv6-ipsec-encryption-bug-in-sctp_v6_xmit.patch @@ -0,0 +1,186 @@ +From 95ee62083cb6453e056562d91f597552021e6ae7 Mon Sep 17 00:00:00 2001 +From: Daniel Borkmann +Date: Wed, 11 Sep 2013 14:58:36 +0000 +Subject: net: sctp: fix ipv6 ipsec encryption bug in sctp_v6_xmit + +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 +--- +diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c +index da613ce..4f52e2c 100644 +--- a/net/sctp/ipv6.c ++++ b/net/sctp/ipv6.c +@@ -204,44 +204,23 @@ out: + in6_dev_put(idev); + } + +-/* Based on tcp_v6_xmit() in tcp_ipv6.c. */ + static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *transport) + { + struct sock *sk = skb->sk; + struct ipv6_pinfo *np = inet6_sk(sk); +- struct flowi6 fl6; +- +- memset(&fl6, 0, sizeof(fl6)); +- +- fl6.flowi6_proto = sk->sk_protocol; +- +- /* Fill in the dest address from the route entry passed with the skb +- * and the source address from the transport. +- */ +- fl6.daddr = transport->ipaddr.v6.sin6_addr; +- fl6.saddr = transport->saddr.v6.sin6_addr; +- +- fl6.flowlabel = np->flow_label; +- IP6_ECN_flow_xmit(sk, fl6.flowlabel); +- if (ipv6_addr_type(&fl6.saddr) & IPV6_ADDR_LINKLOCAL) +- fl6.flowi6_oif = transport->saddr.v6.sin6_scope_id; +- else +- fl6.flowi6_oif = sk->sk_bound_dev_if; +- +- if (np->opt && np->opt->srcrt) { +- struct rt0_hdr *rt0 = (struct rt0_hdr *) np->opt->srcrt; +- fl6.daddr = *rt0->addr; +- } ++ struct flowi6 *fl6 = &transport->fl.u.ip6; + + pr_debug("%s: skb:%p, len:%d, src:%pI6 dst:%pI6\n", __func__, skb, +- skb->len, &fl6.saddr, &fl6.daddr); ++ skb->len, &fl6->saddr, &fl6->daddr); + +- SCTP_INC_STATS(sock_net(sk), SCTP_MIB_OUTSCTPPACKS); ++ IP6_ECN_flow_xmit(sk, fl6->flowlabel); + + if (!(transport->param_flags & SPP_PMTUD_ENABLE)) + skb->local_df = 1; + +- return ip6_xmit(sk, skb, &fl6, np->opt, np->tclass); ++ SCTP_INC_STATS(sock_net(sk), SCTP_MIB_OUTSCTPPACKS); ++ ++ return ip6_xmit(sk, skb, fl6, np->opt, np->tclass); + } + + /* Returns the dst cache entry for the given source and destination ip +@@ -254,10 +233,12 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr, + struct dst_entry *dst = NULL; + struct flowi6 *fl6 = &fl->u.ip6; + struct sctp_bind_addr *bp; ++ struct ipv6_pinfo *np = inet6_sk(sk); + struct sctp_sockaddr_entry *laddr; + union sctp_addr *baddr = NULL; + union sctp_addr *daddr = &t->ipaddr; + union sctp_addr dst_saddr; ++ struct in6_addr *final_p, final; + __u8 matchlen = 0; + __u8 bmatchlen; + sctp_scope_t scope; +@@ -281,7 +262,8 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr, + pr_debug("src=%pI6 - ", &fl6->saddr); + } + +- dst = ip6_dst_lookup_flow(sk, fl6, NULL, false); ++ final_p = fl6_update_dst(fl6, np->opt, &final); ++ dst = ip6_dst_lookup_flow(sk, fl6, final_p, false); + if (!asoc || saddr) + goto out; + +@@ -333,10 +315,12 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr, + } + } + rcu_read_unlock(); ++ + if (baddr) { + fl6->saddr = baddr->v6.sin6_addr; + fl6->fl6_sport = baddr->v6.sin6_port; +- dst = ip6_dst_lookup_flow(sk, fl6, NULL, false); ++ final_p = fl6_update_dst(fl6, np->opt, &final); ++ dst = ip6_dst_lookup_flow(sk, fl6, final_p, false); + } + + out: +-- +cgit v0.9.2 -- cgit