netdev - [PATCH net-next 3/5] ipv6: use READ_ONCE()/WRITE_ONCE() on fib6_table->fib

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241009184405.3752829-4-edumazet@google.com>
Date: Wed,  9 Oct 2024 18:44:03 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>, Jiri Pirko <jiri@...nulli.us>, 
	netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 3/5] ipv6: use READ_ONCE()/WRITE_ONCE() on fib6_table->fib_seq

Using RTNL to protect ops->fib_rules_seq reads seems a big hammer.

Writes are protected by RTNL.
We can use READ_ONCE() when reading it.

Constify 'struct net' argument of fib6_tables_seq_read() and
fib6_rules_seq_read().

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/ip6_fib.h |  8 ++++----
 net/ipv6/fib6_rules.c |  2 +-
 net/ipv6/ip6_fib.c    | 14 +++++++-------
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 6cb867ce4878423fbb9049e69445a6dbf8f31ba7..7c87873ae211c5fa80d34e8f3b8df0e813976390 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -394,7 +394,7 @@ struct fib6_table {
 	struct fib6_node	tb6_root;
 	struct inet_peer_base	tb6_peers;
 	unsigned int		flags;
-	unsigned int		fib_seq;
+	unsigned int		fib_seq; /* writes protected by rtnl_mutex */
 	struct hlist_head       tb6_gc_hlist;	/* GC candidates */
 #define RT6_TABLE_HAS_DFLT_ROUTER	BIT(0)
 };
@@ -563,7 +563,7 @@ int call_fib6_notifiers(struct net *net, enum fib_event_type event_type,
 int __net_init fib6_notifier_init(struct net *net);
 void __net_exit fib6_notifier_exit(struct net *net);
 
-unsigned int fib6_tables_seq_read(struct net *net);
+unsigned int fib6_tables_seq_read(const struct net *net);
 int fib6_tables_dump(struct net *net, struct notifier_block *nb,
 		     struct netlink_ext_ack *extack);
 
@@ -632,7 +632,7 @@ void fib6_rules_cleanup(void);
 bool fib6_rule_default(const struct fib_rule *rule);
 int fib6_rules_dump(struct net *net, struct notifier_block *nb,
 		    struct netlink_ext_ack *extack);
-unsigned int fib6_rules_seq_read(struct net *net);
+unsigned int fib6_rules_seq_read(const struct net *net);
 
 static inline bool fib6_rules_early_flow_dissect(struct net *net,
 						 struct sk_buff *skb,
@@ -676,7 +676,7 @@ static inline int fib6_rules_dump(struct net *net, struct notifier_block *nb,
 {
 	return 0;
 }
-static inline unsigned int fib6_rules_seq_read(struct net *net)
+static inline unsigned int fib6_rules_seq_read(const struct net *net)
 {
 	return 0;
 }
diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 04a9ed5e8310f23cb7d947b732be5dd19916bf39..c85c1627cb16ed0bdfe4c6026bb0132cdd7be6b7 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -56,7 +56,7 @@ int fib6_rules_dump(struct net *net, struct notifier_block *nb,
 	return fib_rules_dump(net, nb, AF_INET6, extack);
 }
 
-unsigned int fib6_rules_seq_read(struct net *net)
+unsigned int fib6_rules_seq_read(const struct net *net)
 {
 	return fib_rules_seq_read(net, AF_INET6);
 }
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index eb111d20615c6274647eeb413d0b9475aaa3ae6c..cea160b249d2d75d03c867d2298da76eb0c7114e 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -345,17 +345,17 @@ static void __net_init fib6_tables_init(struct net *net)
 
 #endif
 
-unsigned int fib6_tables_seq_read(struct net *net)
+unsigned int fib6_tables_seq_read(const struct net *net)
 {
 	unsigned int h, fib_seq = 0;
 
 	rcu_read_lock();
 	for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
-		struct hlist_head *head = &net->ipv6.fib_table_hash[h];
-		struct fib6_table *tb;
+		const struct hlist_head *head = &net->ipv6.fib_table_hash[h];
+		const struct fib6_table *tb;
 
 		hlist_for_each_entry_rcu(tb, head, tb6_hlist)
-			fib_seq += tb->fib_seq;
+			fib_seq += READ_ONCE(tb->fib_seq);
 	}
 	rcu_read_unlock();
 
@@ -400,7 +400,7 @@ int call_fib6_entry_notifiers(struct net *net,
 		.rt = rt,
 	};
 
-	rt->fib6_table->fib_seq++;
+	WRITE_ONCE(rt->fib6_table->fib_seq, rt->fib6_table->fib_seq + 1);
 	return call_fib6_notifiers(net, event_type, &info.info);
 }
 
@@ -416,7 +416,7 @@ int call_fib6_multipath_entry_notifiers(struct net *net,
 		.nsiblings = nsiblings,
 	};
 
-	rt->fib6_table->fib_seq++;
+	WRITE_ONCE(rt->fib6_table->fib_seq, rt->fib6_table->fib_seq + 1);
 	return call_fib6_notifiers(net, event_type, &info.info);
 }
 
@@ -427,7 +427,7 @@ int call_fib6_entry_notifiers_replace(struct net *net, struct fib6_info *rt)
 		.nsiblings = rt->fib6_nsiblings,
 	};
 
-	rt->fib6_table->fib_seq++;
+	WRITE_ONCE(rt->fib6_table->fib_seq, rt->fib6_table->fib_seq + 1);
 	return call_fib6_notifiers(net, FIB_EVENT_ENTRY_REPLACE, &info.info);
 }
 
-- 
2.47.0.rc0.187.ge670bccf7e-goog