linux-kernel - [PATCH 4.8 29/35] net: ipv6: Do not consider link state for nexthop validation

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Message-Id: <20161113112422.021704429@linuxfoundation.org>
Date:   Sun, 13 Nov 2016 12:27:43 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Ahern <dsa@...ulusnetworks.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.8 29/35] net: ipv6: Do not consider link state for nexthop validation

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Ahern <dsa@...ulusnetworks.com>


[ Upstream commit d5d32e4b76687f4df9ad3ba8d3702b7347f51fa6 ]

Similar to IPv4, do not consider link state when validating next hops.

Currently, if the link is down default routes can fail to insert:
 $ ip -6 ro add vrf blue default via 2100:2::64 dev eth2
 RTNETLINK answers: No route to host

With this patch the command succeeds.

Fixes: 8c14586fc320 ("net: ipv6: Use passed in table for nexthop lookups")
Signed-off-by: David Ahern <dsa@...ulusnetworks.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 include/net/ip6_route.h |    1 +
 net/ipv6/route.c        |    6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)

--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -32,6 +32,7 @@ struct route_info {
 #define RT6_LOOKUP_F_SRCPREF_TMP	0x00000008
 #define RT6_LOOKUP_F_SRCPREF_PUBLIC	0x00000010
 #define RT6_LOOKUP_F_SRCPREF_COA	0x00000020
+#define RT6_LOOKUP_F_IGNORE_LINKSTATE	0x00000040
 
 /* We do not (yet ?) support IPv6 jumbograms (RFC 2675)
  * Unlike IPv4, hdr->seg_len doesn't include the IPv6 header
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -656,7 +656,8 @@ static struct rt6_info *find_match(struc
 	struct net_device *dev = rt->dst.dev;
 
 	if (dev && !netif_carrier_ok(dev) &&
-	    idev->cnf.ignore_routes_with_linkdown)
+	    idev->cnf.ignore_routes_with_linkdown &&
+	    !(strict & RT6_LOOKUP_F_IGNORE_LINKSTATE))
 		goto out;
 
 	if (rt6_check_expired(rt))
@@ -1050,6 +1051,7 @@ struct rt6_info *ip6_pol_route(struct ne
 	int strict = 0;
 
 	strict |= flags & RT6_LOOKUP_F_IFACE;
+	strict |= flags & RT6_LOOKUP_F_IGNORE_LINKSTATE;
 	if (net->ipv6.devconf_all->forwarding == 0)
 		strict |= RT6_LOOKUP_F_REACHABLE;
 
@@ -1783,7 +1785,7 @@ static struct rt6_info *ip6_nh_lookup_ta
 	};
 	struct fib6_table *table;
 	struct rt6_info *rt;
-	int flags = RT6_LOOKUP_F_IFACE;
+	int flags = RT6_LOOKUP_F_IFACE | RT6_LOOKUP_F_IGNORE_LINKSTATE;
 
 	table = fib6_get_table(net, cfg->fc_table);
 	if (!table)