From efd019f933a538e4147aee811e6b2dd7a1aafdef Mon Sep 17 00:00:00 2001 From: Hangbin Liu Date: Thu, 30 Jul 2015 14:28:42 +0800 Subject: net/ipv6: add sysctl option accept_ra_min_hop_limit commit 8013d1d7eafb0589ca766db6b74026f76b7f5cb4 upstream. 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 Acked-by: YOSHIFUJI Hideaki Signed-off-by: David S. Miller [ luis: backported to 3.16: - added missing DEVCONF_* as suggested by Yoshfuji so that uapi contains the same values as mainline - adjusted context ] Signed-off-by: Luis Henriques --- Documentation/networking/ip-sysctl.txt | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'Documentation') diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index ab42c95f9985..36aa39eee48f 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -1210,6 +1210,14 @@ accept_ra_defrtr - BOOLEAN Functional default: enabled if accept_ra is enabled. disabled if accept_ra is disabled. +accept_ra_min_hop_limit - INTEGER + Minimum hop limit Information in Router Advertisement. + + Hop limit Information in Router Advertisement less than this + variable shall be ignored. + + Default: 1 + accept_ra_pinfo - BOOLEAN Learn Prefix Information in Router Advertisement. -- cgit v1.2.3