ping? thanks.
On 2016年02月03日 10:56, Yuki Machida wrote: > Please apply the following patch to v4.1.x. > > By commit 6fd99094de2b ("ipv6: Don't reduce hop limit for an interface") > that have been added in the 4.0-rc7, it no longer comply with RFC4861. > This problem has been fixed in the commit 8013d1d7eafb > ("net/ipv6: add sysctl option accept_ra_min_hop_limit") > in 4.3-rc1, but 4.1.x is still. > > [ Upstream 8013d1d7eafb0589ca766db6b74026f76b7f5cb4 ] > > 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 <liuhang...@gmail.com> > Acked-by: YOSHIFUJI Hideaki <hideaki.yoshif...@miraclelinux.com> > Signed-off-by: David S. Miller <da...@davemloft.net> > --- > Documentation/networking/ip-sysctl.txt | 8 ++++++++ > include/linux/ipv6.h | 1 + > include/uapi/linux/ipv6.h | 2 ++ > net/ipv6/addrconf.c | 10 ++++++++++ > net/ipv6/ndisc.c | 16 +++++++--------- > 5 files changed, 28 insertions(+), 9 deletions(-) > > diff --git a/Documentation/networking/ip-sysctl.txt > b/Documentation/networking/ip-sysctl.txt > index 071fb18..07fad3d 100644 > --- a/Documentation/networking/ip-sysctl.txt > +++ b/Documentation/networking/ip-sysctl.txt > @@ -1321,6 +1321,14 @@ accept_ra_from_local - BOOLEAN > disabled if accept_ra_from_local is disabled > on a specific interface. > > +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. > > diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h > index e4b4649..01c2592 100644 > --- a/include/linux/ipv6.h > +++ b/include/linux/ipv6.h > @@ -29,6 +29,7 @@ struct ipv6_devconf { > __s32 max_desync_factor; > __s32 max_addresses; > __s32 accept_ra_defrtr; > + __s32 accept_ra_min_hop_limit; > __s32 accept_ra_pinfo; > #ifdef CONFIG_IPV6_ROUTER_PREF > __s32 accept_ra_rtr_pref; > diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h > index 5efa54a..21cfddf 100644 > --- a/include/uapi/linux/ipv6.h > +++ b/include/uapi/linux/ipv6.h > @@ -171,6 +171,8 @@ enum { > DEVCONF_USE_OPTIMISTIC, > DEVCONF_ACCEPT_RA_MTU, > DEVCONF_STABLE_SECRET, > + __DEVCONF_USE_OIF_ADDRS_ONLY, /* not implemented */ > + DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT, > DEVCONF_MAX > }; > > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index f4795b0..28c4bc5 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -195,6 +195,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = { > .max_addresses = IPV6_MAX_ADDRESSES, > .accept_ra_defrtr = 1, > .accept_ra_from_local = 0, > + .accept_ra_min_hop_limit= 1, > .accept_ra_pinfo = 1, > #ifdef CONFIG_IPV6_ROUTER_PREF > .accept_ra_rtr_pref = 1, > @@ -236,6 +237,7 @@ static struct ipv6_devconf ipv6_devconf_dflt > __read_mostly = { > .max_addresses = IPV6_MAX_ADDRESSES, > .accept_ra_defrtr = 1, > .accept_ra_from_local = 0, > + .accept_ra_min_hop_limit= 1, > .accept_ra_pinfo = 1, > #ifdef CONFIG_IPV6_ROUTER_PREF > .accept_ra_rtr_pref = 1, > @@ -4565,6 +4567,7 @@ static inline void ipv6_store_devconf(struct > ipv6_devconf *cnf, > array[DEVCONF_MAX_DESYNC_FACTOR] = cnf->max_desync_factor; > array[DEVCONF_MAX_ADDRESSES] = cnf->max_addresses; > array[DEVCONF_ACCEPT_RA_DEFRTR] = cnf->accept_ra_defrtr; > + array[DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT] = cnf->accept_ra_min_hop_limit; > array[DEVCONF_ACCEPT_RA_PINFO] = cnf->accept_ra_pinfo; > #ifdef CONFIG_IPV6_ROUTER_PREF > array[DEVCONF_ACCEPT_RA_RTR_PREF] = cnf->accept_ra_rtr_pref; > @@ -5458,6 +5461,13 @@ static struct addrconf_sysctl_table > .proc_handler = proc_dointvec, > }, > { > + .procname = "accept_ra_min_hop_limit", > + .data = &ipv6_devconf.accept_ra_min_hop_limit, > + .maxlen = sizeof(int), > + .mode = 0644, > + .proc_handler = proc_dointvec, > + }, > + { > .procname = "accept_ra_pinfo", > .data = &ipv6_devconf.accept_ra_pinfo, > .maxlen = sizeof(int), > diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c > index 96f153c..abb0bdd 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: >