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DoS against IPv6 stacks due to improper handling of RA (rhbz 1203712 1208491)

This commit is contained in:
Josh Boyer 2015-04-02 08:23:52 -04:00
parent c0c5b9742f
commit 92f85ec311
2 changed files with 55 additions and 0 deletions
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46
ipv6-Don-t-reduce-hop-limit-for-an-interface.patch Normal file
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@ -0,0 +1,46 @@
From: "D.S. Ljungmark" <ljungmark@modio.se>
Date: Wed, 25 Mar 2015 09:28:15 +0100
Subject: [PATCH] ipv6: Don't reduce hop limit for an interface
A local route may have a lower hop_limit set than global routes do.
RFC 3756, Section 4.2.7, "Parameter Spoofing"
> 1. The attacker includes a Current Hop Limit of one or another small
> number which the attacker knows will cause legitimate packets to
> be dropped before they reach their destination.
> As an example, one possible approach to mitigate this threat is to
> ignore very small hop limits. The nodes could implement a
> configurable minimum hop limit, and ignore attempts to set it below
> said limit.
Signed-off-by: D.S. Ljungmark <ljungmark@modio.se>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
net/ipv6/ndisc.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 471ed24aabae..14ecdaf06bf7 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1218,7 +1218,14 @@ static void ndisc_router_discovery(struct sk_buff *skb)
if (rt)
rt6_set_expires(rt, jiffies + (HZ * lifetime));
if (ra_msg->icmph.icmp6_hop_limit) {
- in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit;
+ /* Only set hop_limit on the interface if it is higher than
+ * the current hop_limit.
+ */
+ if (in6_dev->cnf.hop_limit < ra_msg->icmph.icmp6_hop_limit) {
+ in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit;
+ } else {
+ ND_PRINTK(2, warn, "RA: Got route advertisement with lower hop_limit than current\n");
+ }
if (rt)
dst_metric_set(&rt->dst, RTAX_HOPLIMIT,
ra_msg->icmph.icmp6_hop_limit);
--
2.1.0

9
kernel.spec
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@ -634,6 +634,9 @@ Patch26174: Input-ALPS-fix-max-coordinates-for-v5-and-v7-protoco.patch
#CVE-2015-2150 rhbz 1196266 1200397
Patch26175: xen-pciback-Don-t-disable-PCI_COMMAND-on-PCI-device-.patch
#CVE-2015-XXXX rhbz 1203712 1208491
Patch26177: ipv6-Don-t-reduce-hop-limit-for-an-interface.patch
# END OF PATCH DEFINITIONS
%endif
@ -1379,6 +1382,9 @@ ApplyPatch Input-ALPS-fix-max-coordinates-for-v5-and-v7-protoco.patch
#CVE-2015-2150 rhbz 1196266 1200397
ApplyPatch xen-pciback-Don-t-disable-PCI_COMMAND-on-PCI-device-.patch
#CVE-2015-XXXX rhbz 1203712 1208491
ApplyPatch ipv6-Don-t-reduce-hop-limit-for-an-interface.patch
# END OF PATCH APPLICATIONS
%endif
@ -2229,6 +2235,9 @@ fi
#
#
%changelog
* Thu Apr 02 2015 Josh Boyer <jwboyer@fedoraproject.org>
- DoS against IPv6 stacks due to improper handling of RA (rhbz 1203712 1208491)
* Wed Apr 01 2015 Josh Boyer <jwboyer@fedoraproject.org> - 4.0.0-0.rc6.git1.1
- Linux v4.0-rc6-31-gd4039314d0b1
- CVE-2015-2150 xen: NMIs triggerable by guests (rhbz 1196266 1200397)