From mboxrd@z Thu Jan 1 00:00:00 1970 From: Francois-Xavier Le Bail Subject: [PATCH net-next v5] IPv6: add the option to use anycast addresses as source addresses in echo reply Date: Tue, 7 Jan 2014 14:57:27 +0100 Message-ID: <1389103047-3380-1-git-send-email-fx.lebail@yahoo.com> Cc: Hannes Frederic Sowa , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki Yoshifuji , Patrick McHardy , Francois-Xavier Le Bail To: netdev@vger.kernel.org Return-path: Received: from smtp07.smtpout.orange.fr ([80.12.242.129]:23735 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752617AbaAGOOX (ORCPT ); Tue, 7 Jan 2014 09:14:23 -0500 Sender: netdev-owner@vger.kernel.org List-ID: This change allows to follow a recommandation of RFC4942. - Add "anycast_src_echo_reply" sysctl to control the use of anycast addresses as source addresses for ICMPv6 echo reply. This sysctl is false by default to preserve existing behavior. - Add inline check ipv6_anycast_destination(). - Use them 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 --- v4: update Subject and Documentation, this work also with anycast addresses created via API, not just with Subnet-Router anycast addresses. v5: alternative way, replace ipv6_chk_acast_addr() test by ipv6_anycast_destination() test. Documentation/networking/ip-sysctl.txt | 7 +++++++ include/net/ip6_route.h | 7 +++++++ include/net/netns/ipv6.h | 1 + net/ipv6/icmp.c | 4 +++- net/ipv6/sysctl_net_ipv6.c | 8 ++++++++ 5 files changed, 26 insertions(+), 1 deletion(-) diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index d71afa8..7373115 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 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/ip6_route.h b/include/net/ip6_route.h index 1fb6cdd..017badb 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -152,6 +152,13 @@ static inline bool ipv6_unicast_destination(const struct sk_buff *skb) return rt->rt6i_flags & RTF_LOCAL; } +static inline bool ipv6_anycast_destination(const struct sk_buff *skb) +{ + struct rt6_info *rt = (struct rt6_info *) skb_dst(skb); + + return rt->rt6i_flags & RTF_ANYCAST; +} + int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)); static inline int ip6_skb_dst_mtu(struct sk_buff *skb) 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..9a809a4 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_anycast_destination(skb))) 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)