From: Paolo Abeni <pabeni@redhat.com>
Date: Wed, 20 Nov 2019 13:47:34 +0100
Subject: ipv6: keep track of routes using src
Patch-mainline: v5.5-rc1
Git-commit: b9b33e7c24af1cddc7697056f1664279a40d9a4a
References: bsc#1154353

Use a per namespace counter, increment it on successful creation
of any route using the source address, decrement it on deletion
of such routes.

This allows us to check easily if the routing decision in the
current namespace depends on the packet source. Will be used
by the next patch.

Suggested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/net/ip6_fib.h    |   30 ++++++++++++++++++++++++++++++
 include/net/netns/ipv6.h |    3 +++
 net/ipv6/ip6_fib.c       |    4 ++++
 net/ipv6/route.c         |    3 +++
 4 files changed, 40 insertions(+)

--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -90,7 +90,32 @@ struct fib6_gc_args {
 
 #ifndef CONFIG_IPV6_SUBTREES
 #define FIB6_SUBTREE(fn)	NULL
+
+static inline bool fib6_routes_require_src(const struct net *net)
+{
+	return false;
+}
+
+static inline void fib6_routes_require_src_inc(struct net *net) {}
+static inline void fib6_routes_require_src_dec(struct net *net) {}
+
 #else
+
+static inline bool fib6_routes_require_src(const struct net *net)
+{
+	return net->ipv6.fib6_routes_require_src > 0;
+}
+
+static inline void fib6_routes_require_src_inc(struct net *net)
+{
+	net->ipv6.fib6_routes_require_src++;
+}
+
+static inline void fib6_routes_require_src_dec(struct net *net)
+{
+	net->ipv6.fib6_routes_require_src--;
+}
+
 #define FIB6_SUBTREE(fn)	(rcu_dereference_protected((fn)->subtree, 1))
 #endif
 
@@ -212,6 +237,11 @@ static inline struct inet6_dev *ip6_dst_
 	return ((struct rt6_info *)dst)->rt6i_idev;
 }
 
+static inline bool fib6_requires_src(const struct fib6_info *rt)
+{
+	return rt->fib6_src.plen > 0;
+}
+
 static inline void fib6_clean_expires(struct fib6_info *f6i)
 {
 	f6i->fib6_flags &= ~RTF_EXPIRES;
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -83,6 +83,9 @@ struct netns_ipv6 {
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 	unsigned int		fib6_rules_require_fldissect;
 	bool			fib6_has_custom_rules;
+#ifdef CONFIG_IPV6_SUBTREES
+	unsigned int		fib6_routes_require_src;
+#endif
 	struct rt6_info         *ip6_prohibit_entry;
 	struct rt6_info         *ip6_blk_hole_entry;
 	struct fib6_table       *fib6_local_tbl;
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1461,6 +1461,8 @@ out:
 		}
 #endif
 		goto failure;
+	} else if (fib6_requires_src(rt)) {
+		fib6_routes_require_src_inc(info->nl_net);
 	}
 	return err;
 
@@ -1933,6 +1935,8 @@ int fib6_del(struct fib6_info *rt, struc
 		struct fib6_info *cur = rcu_dereference_protected(*rtp,
 					lockdep_is_held(&table->tb6_lock));
 		if (rt == cur) {
+			if (fib6_requires_src(cur))
+				fib6_routes_require_src_dec(info->nl_net);
 			fib6_del_route(table, fn, rtp, info);
 			return 0;
 		}
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6201,6 +6201,9 @@ static int __net_init ip6_route_net_init
 	dst_init_metrics(&net->ipv6.ip6_blk_hole_entry->dst,
 			 ip6_template_metrics, true);
 	INIT_LIST_HEAD(&net->ipv6.ip6_blk_hole_entry->rt6i_uncached);
+#ifdef CONFIG_IPV6_SUBTREES
+	net->ipv6.fib6_routes_require_src = 0;
+#endif
 #endif
 
 	net->ipv6.sysctl.flush_delay = 0;