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Date: Fri, 3 Jan 2014 14:02:51 +0100
From: Francois-Xavier Le Bail <fx.lebail@...oo.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Alexey Kuznetsov <kuznet@....inr.ac.ru>,
James Morris <jmorris@...ei.org>,
Hideaki Yoshifuji <yoshfuji@...ux-ipv6.org>,
Patrick McHardy <kaber@...sh.net>,
Francois-Xavier Le Bail <fx.lebail@...oo.com>
Subject: [PATCH net-next v3] IPv6: use Subnet-Router anycast addresses as source addresses in echo reply
This change allows to follow a recommandation of RFC4942.
- Add "anycast_src_echo_reply" sysctl to control the use of Subnet-Router
anycast addresses as source addresses for ICMPv6 echo reply. This sysctl
is false by default to preserve existing behavior.
- Use it in icmpv6_echo_reply().
Reference:
RFC4942 - IPv6 Transition/Coexistence Security Considerations
(http://tools.ietf.org/html/rfc4942#section-2.1.6)
2.1.6. Anycast Traffic Identification and Security
[...]
To avoid exposing knowledge about the internal structure of the
network, it is recommended that anycast servers now take advantage of
the ability to return responses with the anycast address as the
source address if possible.
Signed-off-by: Francois-Xavier Le Bail <fx.lebail@...oo.com>
---
Documentation/networking/ip-sysctl.txt | 7 +++++++
include/net/netns/ipv6.h | 1 +
net/ipv6/icmp.c | 4 +++-
net/ipv6/sysctl_net_ipv6.c | 8 ++++++++
4 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index d71afa8..3044df7 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1094,6 +1094,13 @@ bindv6only - BOOLEAN
Default: FALSE (as specified in RFC3493)
+anycast_src_echo_reply - BOOLEAN
+ Controls the use of Subnet-Router anycast addresses as source addresses
+ for ICMPv6 echo reply
+ TRUE: enabled
+ FALSE: disabled
+ Default: FALSE
+
IPv6 Fragmentation:
ip6frag_high_thresh - INTEGER
diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index 0fb2401..76fc7d1 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -73,6 +73,7 @@ struct netns_ipv6 {
#endif
atomic_t dev_addr_genid;
atomic_t rt_genid;
+ int anycast_src_echo_reply;
};
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 5d42009..65c8619 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -556,7 +556,9 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
saddr = &ipv6_hdr(skb)->daddr;
- if (!ipv6_unicast_destination(skb))
+ if (!ipv6_unicast_destination(skb) &&
+ !(net->ipv6.anycast_src_echo_reply &&
+ ipv6_chk_acast_addr(net, NULL, saddr)))
saddr = NULL;
memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 107b2f1..6b6a2c8 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -24,6 +24,13 @@ static struct ctl_table ipv6_table_template[] = {
.mode = 0644,
.proc_handler = proc_dointvec
},
+ {
+ .procname = "anycast_src_echo_reply",
+ .data = &init_net.ipv6.anycast_src_echo_reply,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec
+ },
{ }
};
@@ -51,6 +58,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
if (!ipv6_table)
goto out;
ipv6_table[0].data = &net->ipv6.sysctl.bindv6only;
+ ipv6_table[1].data = &net->ipv6.anycast_src_echo_reply;
ipv6_route_table = ipv6_route_sysctl_init(net);
if (!ipv6_route_table)
--
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