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

[Brian Vazquez]

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 <d...@cumulusnetworks.com>
Signed-off-by: Brian Vazquez <bria...@google.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