linux-kernel - [PATCH] net: ipv6: fix __rt6_purge_dflt_routers when forwarding is not set on all ifaces

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Message-Id: <20200901065758.1141786-1-brianvv@google.com>
Date:   Mon, 31 Aug 2020 23:57:58 -0700
From:   Brian Vazquez <brianvv@...gle.com>
To:     Brian Vazquez <brianvv.kernel@...il.com>,
        Brian Vazquez <brianvv@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S . Miller" <davem@...emloft.net>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        David Ahern <dsa@...ulusnetworks.com>
Subject: [PATCH] net: ipv6: fix __rt6_purge_dflt_routers when forwarding is
 not set on all ifaces

The problem is exposed when the system has multiple ifaces and
forwarding is enabled on a subset of them, __rt6_purge_dflt_routers will
clean the default route on all the ifaces which is not desired.

This patches fixes that by cleaning only the routes where the iface has
forwarding enabled.

Fixes: 830218c1add1 ("net: ipv6: Fix processing of RAs in presence of VRF")
Cc: David Ahern <dsa@...ulusnetworks.com>
Signed-off-by: Brian Vazquez <brianvv@...gle.com>
---
 net/ipv6/route.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 5e7e25e2523a..41181cd489ea 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4283,6 +4283,7 @@ static void __rt6_purge_dflt_routers(struct net *net,
 				     struct fib6_table *table)
 {
 	struct fib6_info *rt;
+	bool deleted = false;
 
 restart:
 	rcu_read_lock();
@@ -4291,16 +4292,19 @@ static void __rt6_purge_dflt_routers(struct net *net,
 		struct inet6_dev *idev = dev ? __in6_dev_get(dev) : NULL;
 
 		if (rt->fib6_flags & (RTF_DEFAULT | RTF_ADDRCONF) &&
-		    (!idev || idev->cnf.accept_ra != 2) &&
+		    (!idev || (idev->cnf.forwarding == 1 &&
+			       idev->cnf.accept_ra != 2)) &&
 		    fib6_info_hold_safe(rt)) {
 			rcu_read_unlock();
 			ip6_del_rt(net, rt, false);
+			deleted = true;
 			goto restart;
 		}
 	}
 	rcu_read_unlock();
 
-	table->flags &= ~RT6_TABLE_HAS_DFLT_ROUTER;
+	if (deleted)
+		table->flags &= ~RT6_TABLE_HAS_DFLT_ROUTER;
 }
 
 void rt6_purge_dflt_routers(struct net *net)
-- 
2.28.0.402.g5ffc5be6b7-goog