net/ipv6: Revert remove expired routes with a separated list of routes

This reverts commit 3dec89b14d37ee635e772636dad3f09f78f1ab87.

The commit has some race conditions given how expires is managed on a
fib6_info in relation to gc start, adding the entry to the gc list and
setting the timer value leading to UAF. Revert the commit and try again
in a later release.

Fixes: 3dec89b14d37 ("net/ipv6: Remove expired routes with a separated list of routes")
Cc: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231219030243.25687-1-dsahern@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 13 insertions, 51 deletions

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 1ba9f4ddf2f6..9ba6413fd2e3 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -179,9 +179,6 @@ struct fib6_info {
 
 	refcount_t			fib6_ref;
 	unsigned long			expires;
-
-	struct hlist_node		gc_link;
-
 	struct dst_metrics		*fib6_metrics;
 #define fib6_pmtu		fib6_metrics->metrics[RTAX_MTU-1]
 
@@ -250,6 +247,19 @@ 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;
+	f6i->expires = 0;
+}
+
+static inline void fib6_set_expires(struct fib6_info *f6i,
+				    unsigned long expires)
+{
+	f6i->expires = expires;
+	f6i->fib6_flags |= RTF_EXPIRES;
+}
+
 static inline bool fib6_check_expired(const struct fib6_info *f6i)
 {
 	if (f6i->fib6_flags & RTF_EXPIRES)
@@ -257,11 +267,6 @@ static inline bool fib6_check_expired(const struct fib6_info *f6i)
 	return false;
 }
 
-static inline bool fib6_has_expires(const struct fib6_info *f6i)
-{
-	return f6i->fib6_flags & RTF_EXPIRES;
-}
-
 /* Function to safely get fn->fn_sernum for passed in rt
  * and store result in passed in cookie.
  * Return true if we can get cookie safely
@@ -383,7 +388,6 @@ struct fib6_table {
 	struct inet_peer_base	tb6_peers;
 	unsigned int		flags;
 	unsigned int		fib_seq;
-	struct hlist_head       tb6_gc_hlist;	/* GC candidates */
 #define RT6_TABLE_HAS_DFLT_ROUTER	BIT(0)
 };
 
@@ -500,48 +504,6 @@ void fib6_gc_cleanup(void);
 
 int fib6_init(void);
 
-/* fib6_info must be locked by the caller, and fib6_info->fib6_table can be
- * NULL.
- */
-static inline void fib6_set_expires_locked(struct fib6_info *f6i,
-					   unsigned long expires)
-{
-	struct fib6_table *tb6;
-
-	tb6 = f6i->fib6_table;
-	f6i->expires = expires;
-	if (tb6 && !fib6_has_expires(f6i))
-		hlist_add_head(&f6i->gc_link, &tb6->tb6_gc_hlist);
-	f6i->fib6_flags |= RTF_EXPIRES;
-}
-
-/* fib6_info must be locked by the caller, and fib6_info->fib6_table can be
- * NULL.  If fib6_table is NULL, the fib6_info will no be inserted into the
- * list of GC candidates until it is inserted into a table.
- */
-static inline void fib6_set_expires(struct fib6_info *f6i,
-				    unsigned long expires)
-{
-	spin_lock_bh(&f6i->fib6_table->tb6_lock);
-	fib6_set_expires_locked(f6i, expires);
-	spin_unlock_bh(&f6i->fib6_table->tb6_lock);
-}
-
-static inline void fib6_clean_expires_locked(struct fib6_info *f6i)
-{
-	if (fib6_has_expires(f6i))
-		hlist_del_init(&f6i->gc_link);
-	f6i->fib6_flags &= ~RTF_EXPIRES;
-	f6i->expires = 0;
-}
-
-static inline void fib6_clean_expires(struct fib6_info *f6i)
-{
-	spin_lock_bh(&f6i->fib6_table->tb6_lock);
-	fib6_clean_expires_locked(f6i);
-	spin_unlock_bh(&f6i->fib6_table->tb6_lock);
-}
-
 struct ipv6_route_iter {
 	struct seq_net_private p;
 	struct fib6_walker w;