Re: [PATCH] make TLLAO option for NA packets configurable

[Cosmin Ratiu <cratiu@ixiacom.com>]

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On Thursday 01 October 2009 19:43:56 David Miller wrote:
> Using CLT_UNNUMBERED is a must these days.
>
> Also, please fix the prefixing of the paths in your patch.
> See Documentation/SubmittingPatches in the kernel tree.

Here is the new variant. Please let me know what you think.

And I apologize for using [PATCH] instead of [RFC] in the subject, I don't 
know much about netdev protocol (yet).

Cosmin.

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From 1911a98df800cedf4c3a63b897163e2935c5f602 Mon Sep 17 00:00:00 2001
From: Cosmin Ratiu <cratiu@ixiacom.com>
Date: Thu, 1 Oct 2009 20:27:39 +0300
Subject: [PATCH] ipv6: new sysctl for sending TLLAO with NAs

Neighbor advertisements responding to unicast Neighbor Solicitations did
not include the TLLAO option. This patch makes this configurable via
/proc/sys/net/ipv6/ndisc_force_tllao, which by default is off.

The need for this arose because certain routers expect the TLLAO in some
situations even as a response to unicast NS packets.

Moreover, RFC 2461 recommends on page 24 sending this to avoid a race.

Signed-off-by: Cosmin Ratiu <cratiu@ixiacom.com>
---
 include/net/netns/ipv6.h   |    1 +
 net/ipv6/ndisc.c           |    1 +
 net/ipv6/sysctl_net_ipv6.c |    8 ++++++++
 3 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index dfeb2d7..dd0a95b 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -16,6 +16,7 @@ struct netns_sysctl_ipv6 {
 	struct ctl_table_header *frags_hdr;
 #endif
 	int bindv6only;
+	int ndisc_force_tllao;
 	int flush_delay;
 	int ip6_rt_max_size;
 	int ip6_rt_gc_min_interval;
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index f74e4e2..f08cf65 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -598,6 +598,7 @@ static void ndisc_send_na(struct net_device *dev, struct neighbour *neigh,
 	icmp6h.icmp6_solicited = solicited;
 	icmp6h.icmp6_override = override;
 
+	inc_opt |= dev_net(dev)->ipv6.sysctl.ndisc_force_tllao;
 	__ndisc_send(dev, neigh, daddr, src_addr,
 		     &icmp6h, solicited_addr,
 		     inc_opt ? ND_OPT_TARGET_LL_ADDR : 0);
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 0dc6a4e..fb423ce 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -37,6 +37,14 @@ static ctl_table ipv6_table_template[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "ndisc_force_tllao",
+		.data		= &init_net.ipv6.sysctl.ndisc_force_tllao,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec
+	},
 	{ .ctl_name = 0 }
 };
 
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1.6.3.3