1 files changed, 25 insertions, 12 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 7a186e74b1b3..f1de72de273e 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -96,6 +96,14 @@ static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
 static int netlink_dump(struct sock *sk);
 static void netlink_skb_destructor(struct sk_buff *skb);
 
+/* nl_table locking explained:
+ * Lookup and traversal are protected with nl_sk_hash_lock or nl_table_lock
+ * combined with an RCU read-side lock. Insertion and removal are protected
+ * with nl_sk_hash_lock while using RCU list modification primitives and may
+ * run in parallel to nl_table_lock protected lookups. Destruction of the
+ * Netlink socket may only occur *after* nl_table_lock has been acquired
+ * either during or after the socket has been removed from the list.
+ */
 DEFINE_RWLOCK(nl_table_lock);
 EXPORT_SYMBOL_GPL(nl_table_lock);
 static atomic_t nl_table_users = ATOMIC_INIT(0);
@@ -109,10 +117,10 @@ EXPORT_SYMBOL_GPL(nl_sk_hash_lock);
 static int lockdep_nl_sk_hash_is_held(void)
 {
 #ifdef CONFIG_LOCKDEP
-        return (debug_locks) ? lockdep_is_held(&nl_sk_hash_lock) : 1;
-#else
-        return 1;
+        if (debug_locks)
+                return lockdep_is_held(&nl_sk_hash_lock) || lockdep_is_held(&nl_table_lock);
 #endif
+        return 1;
 }
 
 static ATOMIC_NOTIFIER_HEAD(netlink_chain);
@@ -1028,11 +1036,13 @@ static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
         struct netlink_table *table = &nl_table[protocol];
         struct sock *sk;
 
+        read_lock(&nl_table_lock);
         rcu_read_lock();
         sk = __netlink_lookup(table, portid, net);
         if (sk)
                 sock_hold(sk);
         rcu_read_unlock();
+        read_unlock(&nl_table_lock);
 
         return sk;
 }
@@ -1257,9 +1267,6 @@ static int netlink_release(struct socket *sock)
         }
         netlink_table_ungrab();
 
-        /* Wait for readers to complete */
-        synchronize_net();
-
         kfree(nlk->groups);
         nlk->groups = NULL;
 
@@ -1281,6 +1288,7 @@ static int netlink_autobind(struct socket *sock)
 
 retry:
         cond_resched();
+        netlink_table_grab();
         rcu_read_lock();
         if (__netlink_lookup(table, portid, net)) {
                 /* Bind collision, search negative portid values. */
@@ -1288,9 +1296,11 @@ retry:
                 if (rover > -4097)
                         rover = -4097;
                 rcu_read_unlock();
+                netlink_table_ungrab();
                 goto retry;
         }
         rcu_read_unlock();
+        netlink_table_ungrab();
 
         err = netlink_insert(sk, net, portid);
         if (err == -EADDRINUSE)
@@ -2921,14 +2931,16 @@ static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos)
 }
 
 static void *netlink_seq_start(struct seq_file *seq, loff_t *pos)
-        __acquires(RCU)
+        __acquires(nl_table_lock) __acquires(RCU)
 {
+        read_lock(&nl_table_lock);
         rcu_read_lock();
         return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN;
 }
 
 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
+        struct rhashtable *ht;
         struct netlink_sock *nlk;
         struct nl_seq_iter *iter;
         struct net *net;
@@ -2943,19 +2955,19 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
         iter = seq->private;
         nlk = v;
 
-        rht_for_each_entry_rcu(nlk, nlk->node.next, node)
+        i = iter->link;
+        ht = &nl_table[i].hash;
+        rht_for_each_entry(nlk, nlk->node.next, ht, node)
                 if (net_eq(sock_net((struct sock *)nlk), net))
                         return nlk;
 
-        i = iter->link;
         j = iter->hash_idx + 1;
 
         do {
-                struct rhashtable *ht = &nl_table[i].hash;
                 const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
 
                 for (; j < tbl->size; j++) {
-                        rht_for_each_entry_rcu(nlk, tbl->buckets[j], node) {
+                        rht_for_each_entry(nlk, tbl->buckets[j], ht, node) {
                                 if (net_eq(sock_net((struct sock *)nlk), net)) {
                                         iter->link = i;
                                         iter->hash_idx = j;
@@ -2971,9 +2983,10 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 }
 
 static void netlink_seq_stop(struct seq_file *seq, void *v)
-        __releases(RCU)
+        __releases(RCU) __releases(nl_table_lock)
 {
         rcu_read_unlock();
+        read_unlock(&nl_table_lock);
 }