[3.13.y-ckt stable] Patch "net/ipv6: add sysctl option accept_ra_min_hop_limit" has been added to the 3.13.y-ckt tree
Kamal Mostafa
kamal at canonical.com
Wed Mar 9 23:12:35 UTC 2016
This is a note to let you know that I have just added a patch titled
net/ipv6: add sysctl option accept_ra_min_hop_limit
to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue
This patch is scheduled to be released in version 3.13.11-ckt36.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
---8<------------------------------------------------------------
>From 40e9bd70b554306e66aa5a009c332fe03f9342ca Mon Sep 17 00:00:00 2001
From: Hangbin Liu <liuhangbin at gmail.com>
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 <liuhangbin at gmail.com>
Acked-by: YOSHIFUJI Hideaki <hideaki.yoshifuji at miraclelinux.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
Documentation/networking/ip-sysctl.txt | 8 ++++++++
include/linux/ipv6.h | 1 +
include/uapi/linux/ipv6.h | 1 +
net/ipv6/addrconf.c | 10 ++++++++++
net/ipv6/ndisc.c | 16 +++++++---------
5 files changed, 27 insertions(+), 9 deletions(-)
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index b4be7fd..9a11e8d 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1143,6 +1143,14 @@ 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.
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index c56c350..dc80edd 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 593b0e3..f1d3214 100644
--- a/include/uapi/linux/ipv6.h
+++ b/include/uapi/linux/ipv6.h
@@ -163,6 +163,7 @@ enum {
DEVCONF_MLDV1_UNSOLICITED_REPORT_INTERVAL,
DEVCONF_MLDV2_UNSOLICITED_REPORT_INTERVAL,
DEVCONF_SUPPRESS_FRAG_NDISC,
+ DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT,
DEVCONF_MAX
};
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 2be400d..dd8b55b 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -184,6 +184,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
.max_desync_factor = MAX_DESYNC_FACTOR,
.max_addresses = IPV6_MAX_ADDRESSES,
.accept_ra_defrtr = 1,
+ .accept_ra_min_hop_limit= 1,
.accept_ra_pinfo = 1,
#ifdef CONFIG_IPV6_ROUTER_PREF
.accept_ra_rtr_pref = 1,
@@ -220,6 +221,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
.max_desync_factor = MAX_DESYNC_FACTOR,
.max_addresses = IPV6_MAX_ADDRESSES,
.accept_ra_defrtr = 1,
+ .accept_ra_min_hop_limit= 1,
.accept_ra_pinfo = 1,
#ifdef CONFIG_IPV6_ROUTER_PREF
.accept_ra_rtr_pref = 1,
@@ -4125,6 +4127,7 @@ 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;
@@ -4864,6 +4867,13 @@ 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 ac0bbe8..4e62e51 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1190,18 +1190,16 @@ 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:
--
2.7.0
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