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| author | D.S. Ljungmark <ljungmark@modio.se> | 2015-03-25 09:28:15 +0100 |
|---|---|---|
| committer | Brett Rogers <brettrogers11@gmail.com> | 2016-02-20 14:07:17 -0800 |
| commit | b6ad77af717a40d98627ad297b096d5cb1d36eb9 (patch) | |
| tree | 2884de4c1bd4be76e47e54fc3ffa375700003e73 /net | |
| parent | 7263d7854a4418052aafc520e66313ffc8a2bedc (diff) | |
| download | kernel_samsung_smdk4412-b6ad77af717a40d98627ad297b096d5cb1d36eb9.zip kernel_samsung_smdk4412-b6ad77af717a40d98627ad297b096d5cb1d36eb9.tar.gz kernel_samsung_smdk4412-b6ad77af717a40d98627ad297b096d5cb1d36eb9.tar.bz2 | |
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.
Change-Id: I8d9d9cd978b8d5587cc1056dc65683291f0a153a
Signed-off-by: D.S. Ljungmark <ljungmark@modio.se>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv6/ndisc.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index f01c153..d8878ed 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -1284,7 +1284,14 @@ static void ndisc_router_discovery(struct sk_buff *skb) rt->rt6i_expires = 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_PRINTK2(KERN_WARNING, "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); |