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| author | Hangbin Liu <liuhangbin@gmail.com> | 2015-07-30 14:28:42 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-07-30 15:56:40 -0700 |
| commit | 8013d1d7eafb0589ca766db6b74026f76b7f5cb4 (patch) | |
| tree | 95fb6a6dd3b962157ff2a2d9ce2ab6bfb3e1ca59 /net/ipv6/ndisc.c | |
| parent | 2f51a9b8adbb6ad06689ec28342e89f40acb97fc (diff) | |
| download | blackbird-op-linux-8013d1d7eafb0589ca766db6b74026f76b7f5cb4.tar.gz blackbird-op-linux-8013d1d7eafb0589ca766db6b74026f76b7f5cb4.zip | |
net/ipv6: add sysctl option accept_ra_min_hop_limit
Commit 6fd99094de2b ("ipv6: Don't reduce hop limit for an interface")
disabled accept hop limit from RA if it is smaller than the current hop
limit for security stuff. But this behavior kind of break the RFC definition.
RFC 4861, 6.3.4. Processing Received Router Advertisements
A Router Advertisement field (e.g., Cur Hop Limit, Reachable Time,
and Retrans Timer) may contain a value denoting that it is
unspecified. In such cases, the parameter should be ignored and the
host should continue using whatever value it is already using.
If the received Cur Hop Limit value is non-zero, the host SHOULD set
its CurHopLimit variable to the received value.
So add sysctl option accept_ra_min_hop_limit to let user choose the minimum
hop limit value they can accept from RA. And set default to 1 to meet RFC
standards.
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: YOSHIFUJI Hideaki <hideaki.yoshifuji@miraclelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/ndisc.c')
| -rw-r--r-- | net/ipv6/ndisc.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index 0a05b35a90fc..6e184e02fd3c 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -1225,18 +1225,16 @@ 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) { - /* 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) { + if (in6_dev->cnf.accept_ra_min_hop_limit < 256 && + ra_msg->icmph.icmp6_hop_limit) { + if (in6_dev->cnf.accept_ra_min_hop_limit <= ra_msg->icmph.icmp6_hop_limit) { in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit; + if (rt) + dst_metric_set(&rt->dst, RTAX_HOPLIMIT, + ra_msg->icmph.icmp6_hop_limit); } else { - ND_PRINTK(2, warn, "RA: Got route advertisement with lower hop_limit than current\n"); + ND_PRINTK(2, warn, "RA: Got route advertisement with lower hop_limit than minimum\n"); } - if (rt) - dst_metric_set(&rt->dst, RTAX_HOPLIMIT, - ra_msg->icmph.icmp6_hop_limit); } skip_defrtr: |
