[NET]: Make AF_UNIX per network namespace safe [v2]

Because of the global nature of garbage collection, and because of the
cost of per namespace hash tables unix_socket_table has been kept
global.  With a filter added on lookups so we don't see sockets from
the wrong namespace.

Currently I don't fold the namesapce into the hash so multiple
namespaces using the same socket name will be guaranteed a hash
collision.

Changes from v1:
- fixed unix_seq_open
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/unix/af_unix.c

@@ -270,7 +270,8 @@ static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)
 	spin_unlock(&unix_table_lock);
 }
 
-static struct sock *__unix_find_socket_byname(struct sockaddr_un *sunname,
+static struct sock *__unix_find_socket_byname(struct net *net,
+					      struct sockaddr_un *sunname,
 					      int len, int type, unsigned hash)
 {
 	struct sock *s;
@@ -279,6 +280,9 @@ static struct sock *__unix_find_socket_byname(struct sockaddr_un *sunname,
 	sk_for_each(s, node, &unix_socket_table[hash ^ type]) {
 		struct unix_sock *u = unix_sk(s);
 
+		if (s->sk_net != net)
+			continue;
+
 		if (u->addr->len == len &&
 		    !memcmp(u->addr->name, sunname, len))
 			goto found;
@@ -288,21 +292,22 @@ found:
 	return s;
 }
 
-static inline struct sock *unix_find_socket_byname(struct sockaddr_un *sunname,
+static inline struct sock *unix_find_socket_byname(struct net *net,
+						   struct sockaddr_un *sunname,
 						   int len, int type,
 						   unsigned hash)
 {
 	struct sock *s;
 
 	spin_lock(&unix_table_lock);
-	s = __unix_find_socket_byname(sunname, len, type, hash);
+	s = __unix_find_socket_byname(net, sunname, len, type, hash);
 	if (s)
 		sock_hold(s);
 	spin_unlock(&unix_table_lock);
 	return s;
 }
 
-static struct sock *unix_find_socket_byinode(struct inode *i)
+static struct sock *unix_find_socket_byinode(struct net *net, struct inode *i)
 {
 	struct sock *s;
 	struct hlist_node *node;
@@ -312,6 +317,9 @@ static struct sock *unix_find_socket_byinode(struct inode *i)
 		    &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
 		struct dentry *dentry = unix_sk(s)->dentry;
 
+		if (s->sk_net != net)
+			continue;
+
 		if(dentry && dentry->d_inode == i)
 		{
 			sock_hold(s);
@@ -631,9 +639,6 @@ out:
 
 static int unix_create(struct net *net, struct socket *sock, int protocol)
 {
-	if (net != &init_net)
-		return -EAFNOSUPPORT;
-
 	if (protocol && protocol != PF_UNIX)
 		return -EPROTONOSUPPORT;
 
@@ -677,6 +682,7 @@ static int unix_release(struct socket *sock)
 static int unix_autobind(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
+	struct net *net = sk->sk_net;
 	struct unix_sock *u = unix_sk(sk);
 	static u32 ordernum = 1;
 	struct unix_address * addr;
@@ -703,7 +709,7 @@ retry:
 	spin_lock(&unix_table_lock);
 	ordernum = (ordernum+1)&0xFFFFF;
 
-	if (__unix_find_socket_byname(addr->name, addr->len, sock->type,
+	if (__unix_find_socket_byname(net, addr->name, addr->len, sock->type,
 				      addr->hash)) {
 		spin_unlock(&unix_table_lock);
 		/* Sanity yield. It is unusual case, but yet... */
@@ -723,7 +729,8 @@ out:	mutex_unlock(&u->readlock);
 	return err;
 }
 
-static struct sock *unix_find_other(struct sockaddr_un *sunname, int len,
+static struct sock *unix_find_other(struct net *net,
+				    struct sockaddr_un *sunname, int len,
 				    int type, unsigned hash, int *error)
 {
 	struct sock *u;
@@ -741,7 +748,7 @@ static struct sock *unix_find_other(struct sockaddr_un *sunname, int len,
 		err = -ECONNREFUSED;
 		if (!S_ISSOCK(nd.dentry->d_inode->i_mode))
 			goto put_fail;
-		u=unix_find_socket_byinode(nd.dentry->d_inode);
+		u=unix_find_socket_byinode(net, nd.dentry->d_inode);
 		if (!u)
 			goto put_fail;
 
@@ -757,7 +764,7 @@ static struct sock *unix_find_other(struct sockaddr_un *sunname, int len,
 		}
 	} else {
 		err = -ECONNREFUSED;
-		u=unix_find_socket_byname(sunname, len, type, hash);
+		u=unix_find_socket_byname(net, sunname, len, type, hash);
 		if (u) {
 			struct dentry *dentry;
 			dentry = unix_sk(u)->dentry;
@@ -779,6 +786,7 @@ fail:
 static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 {
 	struct sock *sk = sock->sk;
+	struct net *net = sk->sk_net;
 	struct unix_sock *u = unix_sk(sk);
 	struct sockaddr_un *sunaddr=(struct sockaddr_un *)uaddr;
 	struct dentry * dentry = NULL;
@@ -853,7 +861,7 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 
 	if (!sunaddr->sun_path[0]) {
 		err = -EADDRINUSE;
-		if (__unix_find_socket_byname(sunaddr, addr_len,
+		if (__unix_find_socket_byname(net, sunaddr, addr_len,
 					      sk->sk_type, hash)) {
 			unix_release_addr(addr);
 			goto out_unlock;
@@ -919,6 +927,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 			      int alen, int flags)
 {
 	struct sock *sk = sock->sk;
+	struct net *net = sk->sk_net;
 	struct sockaddr_un *sunaddr=(struct sockaddr_un*)addr;
 	struct sock *other;
 	unsigned hash;
@@ -935,7 +944,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 			goto out;
 
 restart:
-		other=unix_find_other(sunaddr, alen, sock->type, hash, &err);
+		other=unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
 		if (!other)
 			goto out;
 
@@ -1015,6 +1024,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 {
 	struct sockaddr_un *sunaddr=(struct sockaddr_un *)uaddr;
 	struct sock *sk = sock->sk;
+	struct net *net = sk->sk_net;
 	struct unix_sock *u = unix_sk(sk), *newu, *otheru;
 	struct sock *newsk = NULL;
 	struct sock *other = NULL;
@@ -1054,7 +1064,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 
 restart:
 	/*  Find listening sock. */
-	other = unix_find_other(sunaddr, addr_len, sk->sk_type, hash, &err);
+	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
 	if (!other)
 		goto out;
 
@@ -1330,6 +1340,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
 {
 	struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
 	struct sock *sk = sock->sk;
+	struct net *net = sk->sk_net;
 	struct unix_sock *u = unix_sk(sk);
 	struct sockaddr_un *sunaddr=msg->msg_name;
 	struct sock *other = NULL;
@@ -1393,7 +1404,7 @@ restart:
 		if (sunaddr == NULL)
 			goto out_free;
 
-		other = unix_find_other(sunaddr, namelen, sk->sk_type,
+		other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
 					hash, &err);
 		if (other==NULL)
 			goto out_free;
@@ -2006,12 +2017,18 @@ static unsigned int unix_poll(struct file * file, struct socket *sock, poll_tabl
 
 
 #ifdef CONFIG_PROC_FS
-static struct sock *unix_seq_idx(int *iter, loff_t pos)
+struct unix_iter_state {
+	struct net *net;
+	int i;
+};
+static struct sock *unix_seq_idx(struct unix_iter_state *iter, loff_t pos)
 {
 	loff_t off = 0;
 	struct sock *s;
 
-	for (s = first_unix_socket(iter); s; s = next_unix_socket(iter, s)) {
+	for (s = first_unix_socket(&iter->i); s; s = next_unix_socket(&iter->i, s)) {
+		if (s->sk_net != iter->net)
+			continue;
 		if (off == pos)
 			return s;
 		++off;
@@ -2022,17 +2039,24 @@ static struct sock *unix_seq_idx(int *iter, loff_t pos)
 
 static void *unix_seq_start(struct seq_file *seq, loff_t *pos)
 {
+	struct unix_iter_state *iter = seq->private;
 	spin_lock(&unix_table_lock);
-	return *pos ? unix_seq_idx(seq->private, *pos - 1) : ((void *) 1);
+	return *pos ? unix_seq_idx(iter, *pos - 1) : ((void *) 1);
 }
 
 static void *unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
+	struct unix_iter_state *iter = seq->private;
+	struct sock *sk = v;
 	++*pos;
 
 	if (v == (void *)1)
-		return first_unix_socket(seq->private);
-	return next_unix_socket(seq->private, v);
+		sk = first_unix_socket(&iter->i);
+	else
+		sk = next_unix_socket(&iter->i, sk);
+	while (sk && (sk->sk_net != iter->net))
+		sk = next_unix_socket(&iter->i, sk);
+	return sk;
 }
 
 static void unix_seq_stop(struct seq_file *seq, void *v)
@@ -2094,7 +2118,27 @@ static const struct seq_operations unix_seq_ops = {
 
 static int unix_seq_open(struct inode *inode, struct file *file)
 {
-	return seq_open_private(file, &unix_seq_ops, sizeof(int));
+	struct unix_iter_state *it;
+
+	it = __seq_open_private(file, &unix_seq_ops,
+				sizeof(struct unix_iter_state));
+	if (it == NULL)
+		return -ENOMEM;
+
+	it->net = get_proc_net(inode);
+	if (it->net == NULL) {
+		seq_release_private(inode, file);
+		return -ENXIO;
+	}
+	return 0;
+}
+
+static int unix_seq_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq = file->private_data;
+	struct unix_iter_state *iter = seq->private;
+	put_net(iter->net);
+	return seq_release_private(inode, file);
 }
 
 static const struct file_operations unix_seq_fops = {
@@ -2102,7 +2146,7 @@ static const struct file_operations unix_seq_fops = {
 	.open		= unix_seq_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= seq_release_private,
+	.release	= unix_seq_release,
 };
 
 #endif
@@ -2113,6 +2157,30 @@ static struct net_proto_family unix_family_ops = {
 	.owner	= THIS_MODULE,
 };
 
+
+static int unix_net_init(struct net *net)
+{
+	int error = -ENOMEM;
+
+#ifdef CONFIG_PROC_FS
+	if (!proc_net_fops_create(net, "unix", 0, &unix_seq_fops))
+		goto out;
+#endif
+	error = 0;
+out:
+	return 0;
+}
+
+static void unix_net_exit(struct net *net)
+{
+	proc_net_remove(net, "unix");
+}
+
+static struct pernet_operations unix_net_ops = {
+	.init = unix_net_init,
+	.exit = unix_net_exit,
+};
+
 static int __init af_unix_init(void)
 {
 	int rc = -1;
@@ -2128,9 +2196,7 @@ static int __init af_unix_init(void)
 	}
 
 	sock_register(&unix_family_ops);
-#ifdef CONFIG_PROC_FS
-	proc_net_fops_create(&init_net, "unix", 0, &unix_seq_fops);
-#endif
+	register_pernet_subsys(&unix_net_ops);
 	unix_sysctl_register();
 out:
 	return rc;
@@ -2140,8 +2206,8 @@ static void __exit af_unix_exit(void)
 {
 	sock_unregister(PF_UNIX);
 	unix_sysctl_unregister();
-	proc_net_remove(&init_net, "unix");
 	proto_unregister(&unix_proto);
+	unregister_pernet_subsys(&unix_net_ops);
 }
 
 module_init(af_unix_init);