[PATCH] fix RTPROT_RA markup of some RA routes in netlink

[PATCH] fix RTPROT_RA markup of some RA routes in netlink

[Denis Ovsienko]

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Hello, list.

This is a small patch I have produced after thoroughly studying the coupling between addrconf and FIB6 functions. I believe this change to improve the transparency of FIB6 as viewed from userspace (by iproute2 in particular). It does resolve an issue I was debugging, where a default route derived from a router advertisement couldn't be told from kernel routes derived from other sources. The difference is meaningful at least for dynamic routing purposes, but other good uses are also possible.

Thank you.

-- 
    Denis Ovsienko

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From 1d969903c6221980360f76abb5e063300e5cf3bb Mon Sep 17 00:00:00 2001
From: Denis Ovsienko <infrastation@yandex.ru>
Date: Fri, 6 Jul 2012 18:08:18 +0400
Subject: [PATCH] fix RTPROT_RA markup of some RA routes in netlink

There are three types of IPv6 routes originated by kernel ND RA code:

* Default routes standing for RA packets with non-zero router lifetime.
* Connected prefix routes standing for a Prefix Information (3) RA TLV.
* Any prefix routes standing for a Route Information (24) RA TLV.

All three types are internally stored using RTPROT_KERNEL or RTPROT_BOOT
protocol code and RTF_ADDRCONF route flag (this is the only purpose for
this flag). The flag isn't directly available in netlink socket space.
Given the need to tell route origin in userspace, for routes with
nexthops in the first turn, rt6_fill_node() tries to distinguish default
router case sending the netlink route structure with RTPROT_RA (this is
respectively the only use case for this protocol code), but to no
success due to a test condition taken wrong. All three types are
delivered with RTPROT_KERNEL.

This change is modelled after the original mailing list posting by Jeff
Haran. It fixes the test condition for the default router case and
extends it for the Route Information case.
---
 net/ipv6/route.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 999a982..2f070d6 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2441,9 +2441,15 @@ static int rt6_fill_node(struct net *net,
 	if (rt->rt6i_flags & RTF_DYNAMIC)
 		rtm->rtm_protocol = RTPROT_REDIRECT;
 	else if (rt->rt6i_flags & RTF_ADDRCONF)
-		rtm->rtm_protocol = RTPROT_KERNEL;
-	else if (rt->rt6i_flags & RTF_DEFAULT)
-		rtm->rtm_protocol = RTPROT_RA;
+	{
+		/* any ND RA route, most probably originated by kernel */
+		if (rt->rt6i_flags & RTF_DEFAULT) /* default router */
+			rtm->rtm_protocol = RTPROT_RA;
+		else if (rt->rt6i_flags & RTF_ROUTEINFO) /* any route w/nexthop */
+			rtm->rtm_protocol = RTPROT_RA;
+		else /* RTF_PREFIX_RT, interface connected prefix route */
+			rtm->rtm_protocol = RTPROT_KERNEL;
+	}
 
 	if (rt->rt6i_flags & RTF_CACHE)
 		rtm->rtm_flags |= RTM_F_CLONED;
-- 
1.7.7.6

Re: [PATCH] fix RTPROT_RA markup of some RA routes in netlink

[David Miller]

Please read Documentation/SubmittingPatches to learn how to submit
a proper patch with proper commit log message and a proper signoff.

The commit message should exactly describe the reason for your change
and how the change is implemented.  It should not contain things like
"Hello" or "This is a patch" or "Thank you" or other irrelevant
verbiage that does not belong in the commit log message.

Thank you.

[PATCH] ipv6: fix RTPROT_RA markup of RA routes w/nexthops

[Denis Ovsienko]

From: Denis Ovsienko <infrastation@yandex.ru>

Userspace implementations of network routing protocols sometimes need to
tell RA-originated IPv6 routes from other kernel routes to make proper
routing decisions. This makes most sense for RA routes with nexthops,
namely, default routes and Route Information routes.

The intended mean of preserving RA route origin in a netlink message is
through indicating RTPROT_RA as protocol code. Function rt6_fill_node()
tried to do that for default routes, but its test condition was taken
wrong. This change is modeled after the original mailing list posting
by Jeff Haran. It fixes the test condition for default route case and
sets the same behaviour for Route Information case (both types use
nexthops). Handling of the 3rd RA route type, Prefix Information, is
left unchanged, as it stands for interface connected routes (without
nexthops).

Signed-off-by: Denis Ovsienko <infrastation@yandex.ru>
---
 net/ipv6/route.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 999a982..238b1ee 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2440,10 +2440,12 @@ static int rt6_fill_node(struct net *net,
 	rtm->rtm_protocol = rt->rt6i_protocol;
 	if (rt->rt6i_flags & RTF_DYNAMIC)
 		rtm->rtm_protocol = RTPROT_REDIRECT;
-	else if (rt->rt6i_flags & RTF_ADDRCONF)
-		rtm->rtm_protocol = RTPROT_KERNEL;
-	else if (rt->rt6i_flags & RTF_DEFAULT)
-		rtm->rtm_protocol = RTPROT_RA;
+	else if (rt->rt6i_flags & RTF_ADDRCONF) {
+		if (rt->rt6i_flags & (RTF_DEFAULT | RTF_ROUTEINFO))
+			rtm->rtm_protocol = RTPROT_RA;
+		else
+			rtm->rtm_protocol = RTPROT_KERNEL;
+	}
 
 	if (rt->rt6i_flags & RTF_CACHE)
 		rtm->rtm_flags |= RTM_F_CLONED;
-- 
1.7.7.6

Re: [PATCH] ipv6: fix RTPROT_RA markup of RA routes w/nexthops

[David Miller]

From: Denis Ovsienko <infrastation@yandex.ru>
Date: Tue, 10 Jul 2012 18:45:50 +0400

> From: Denis Ovsienko <infrastation@yandex.ru>
> 
> Userspace implementations of network routing protocols sometimes need to
> tell RA-originated IPv6 routes from other kernel routes to make proper
> routing decisions. This makes most sense for RA routes with nexthops,
> namely, default routes and Route Information routes.
> 
> The intended mean of preserving RA route origin in a netlink message is
> through indicating RTPROT_RA as protocol code. Function rt6_fill_node()
> tried to do that for default routes, but its test condition was taken
> wrong. This change is modeled after the original mailing list posting
> by Jeff Haran. It fixes the test condition for default route case and
> sets the same behaviour for Route Information case (both types use
> nexthops). Handling of the 3rd RA route type, Prefix Information, is
> left unchanged, as it stands for interface connected routes (without
> nexthops).
> 
> Signed-off-by: Denis Ovsienko <infrastation@yandex.ru>

Applied to net-next, thanks.