[PATCH RFC 30/31] net: Make AF_UNIX per network namespace safe.

["Eric W. Biederman" <ebiederm@xmission.com>]

From: Eric W. Biederman <ebiederm@xmission.com> - unquoted

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
guaranateed a hash collision.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 include/net/af_unix.h      |   10 ++--
 net/unix/af_unix.c         |  116 ++++++++++++++++++++++++++++++++------------
 net/unix/sysctl_net_unix.c |   24 +++++----
 3 files changed, 103 insertions(+), 47 deletions(-)

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index c0398f5..1f40dd2 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -89,12 +89,12 @@ struct unix_sock {
 #define unix_sk(__sk) ((struct unix_sock *)__sk)
 
 #ifdef CONFIG_SYSCTL
-extern int sysctl_unix_max_dgram_qlen;
-extern void unix_sysctl_register(void);
-extern void unix_sysctl_unregister(void);
+DECLARE_PER_NET(int, sysctl_unix_max_dgram_qlen);
+extern void unix_sysctl_register(net_t net);
+extern void unix_sysctl_unregister(net_t net);
 #else
-static inline void unix_sysctl_register(void) {}
-static inline void unix_sysctl_unregister(void) {}
+static inline void unix_sysctl_register(net_t net) {}
+static inline void unix_sysctl_unregister(net_t net) {}
 #endif
 #endif
 #endif
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 8015a03..3f57cb2 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -118,7 +118,7 @@
 #include <linux/security.h>
 #include <net/net_namespace.h>
 
-int sysctl_unix_max_dgram_qlen __read_mostly = 10;
+DEFINE_PER_NET(int, sysctl_unix_max_dgram_qlen) = 10;
 
 struct hlist_head unix_socket_table[UNIX_HASH_SIZE + 1];
 DEFINE_SPINLOCK(unix_table_lock);
@@ -245,7 +245,8 @@ 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(net_t net,
+					      struct sockaddr_un *sunname,
 					      int len, int type, unsigned hash)
 {
 	struct sock *s;
@@ -254,6 +255,9 @@ 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 (!net_eq(s->sk_net, net))
+			continue;
+
 		if (u->addr->len == len &&
 		    !memcmp(u->addr->name, sunname, len))
 			goto found;
@@ -263,21 +267,22 @@ found:
 	return s;
 }
 
-static inline struct sock *unix_find_socket_byname(struct sockaddr_un *sunname,
+static inline struct sock *unix_find_socket_byname(net_t 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(net_t net, struct inode *i)
 {
 	struct sock *s;
 	struct hlist_node *node;
@@ -287,6 +292,9 @@ 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 (!net_eq(s->sk_net, net))
+			continue;
+
 		if(dentry && dentry->d_inode == i)
 		{
 			sock_hold(s);
@@ -588,7 +596,7 @@ static struct sock * unix_create1(net_t net, struct socket *sock)
 				&af_unix_sk_receive_queue_lock_key);
 
 	sk->sk_write_space	= unix_write_space;
-	sk->sk_max_ack_backlog	= sysctl_unix_max_dgram_qlen;
+	sk->sk_max_ack_backlog	= per_net(sysctl_unix_max_dgram_qlen, net);
 	sk->sk_destruct		= unix_sock_destructor;
 	u	  = unix_sk(sk);
 	u->dentry = NULL;
@@ -604,9 +612,6 @@ out:
 
 static int unix_create(net_t net, struct socket *sock, int protocol)
 {
-	if (!net_eq(net, init_net()))
-		return -EAFNOSUPPORT;
-
 	if (protocol && protocol != PF_UNIX)
 		return -EPROTONOSUPPORT;
 
@@ -650,6 +655,7 @@ static int unix_release(struct socket *sock)
 static int unix_autobind(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
+	net_t net = sk->sk_net;
 	struct unix_sock *u = unix_sk(sk);
 	static u32 ordernum = 1;
 	struct unix_address * addr;
@@ -676,7 +682,7 @@ 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... */
@@ -696,7 +702,8 @@ 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(net_t net,
+				    struct sockaddr_un *sunname, int len,
 				    int type, unsigned hash, int *error)
 {
 	struct sock *u;
@@ -714,7 +721,7 @@ 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;
 
@@ -730,7 +737,7 @@ 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;
@@ -752,6 +759,7 @@ fail:
 static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 {
 	struct sock *sk = sock->sk;
+	net_t net = sk->sk_net;
 	struct unix_sock *u = unix_sk(sk);
 	struct sockaddr_un *sunaddr=(struct sockaddr_un *)uaddr;
 	struct dentry * dentry = NULL;
@@ -826,7 +834,7 @@ 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;
@@ -867,6 +875,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 			      int alen, int flags)
 {
 	struct sock *sk = sock->sk;
+	net_t net = sk->sk_net;
 	struct sockaddr_un *sunaddr=(struct sockaddr_un*)addr;
 	struct sock *other;
 	unsigned hash;
@@ -882,7 +891,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 		    !unix_sk(sk)->addr && (err = unix_autobind(sock)) != 0)
 			goto out;
 
-		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;
 
@@ -955,6 +964,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 {
 	struct sockaddr_un *sunaddr=(struct sockaddr_un *)uaddr;
 	struct sock *sk = sock->sk;
+	net_t net = sk->sk_net;
 	struct unix_sock *u = unix_sk(sk), *newu, *otheru;
 	struct sock *newsk = NULL;
 	struct sock *other = NULL;
@@ -994,7 +1004,7 @@ 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;
 
@@ -1273,6 +1283,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
 {
 	struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
 	struct sock *sk = sock->sk;
+	net_t net = sk->sk_net;
 	struct unix_sock *u = unix_sk(sk);
 	struct sockaddr_un *sunaddr=msg->msg_name;
 	struct sock *other = NULL;
@@ -1336,7 +1347,7 @@ 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;
@@ -1935,12 +1946,18 @@ 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 {
+	net_t 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 (!net_eq(s->sk_net, iter->net))
+			continue;
 		if (off == pos) 
 			return s;
 		++off;
@@ -1951,17 +1968,24 @@ 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 && !net_eq(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)
@@ -2025,7 +2049,7 @@ static int unix_seq_open(struct inode *inode, struct file *file)
 {
 	struct seq_file *seq;
 	int rc = -ENOMEM;
-	int *iter = kmalloc(sizeof(int), GFP_KERNEL);
+	struct unix_iter_state *iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 
 	if (!iter)
 		goto out;
@@ -2036,7 +2060,8 @@ static int unix_seq_open(struct inode *inode, struct file *file)
 
 	seq	     = file->private_data;
 	seq->private = iter;
-	*iter = 0;
+	iter->net = get_net(PROC_NET(inode));
+	iter->i = 0;
 out:
 	return rc;
 out_kfree:
@@ -2044,12 +2069,20 @@ out_kfree:
 	goto out;
 }
 
+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 struct file_operations unix_seq_fops = {
 	.owner		= THIS_MODULE,
 	.open		= unix_seq_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= seq_release_private,
+	.release	= unix_seq_release,
 };
 
 #endif
@@ -2060,6 +2093,31 @@ static struct net_proto_family unix_family_ops = {
 	.owner	= THIS_MODULE,
 };
 
+
+static int unix_net_init(net_t net)
+{
+	int error = -ENOMEM;
+#ifdef CONFIG_PROC_FS
+	if (!proc_net_fops_create(net, "unix", 0, &unix_seq_fops))
+		goto out;
+#endif
+	unix_sysctl_register(net);
+	error = 0;
+out:
+	return 0;
+}
+
+static void unix_net_exit(net_t net)
+{
+	unix_sysctl_unregister(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;
@@ -2075,10 +2133,7 @@ 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
-	unix_sysctl_register();
+	register_pernet_subsys(&unix_net_ops);
 out:
 	return rc;
 }
@@ -2086,9 +2141,8 @@ out:
 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);
diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
index eb0bd57..4b59da8 100644
--- a/net/unix/sysctl_net_unix.c
+++ b/net/unix/sysctl_net_unix.c
@@ -14,11 +14,11 @@
 
 #include <net/af_unix.h>
 
-static ctl_table unix_table[] = {
+static DEFINE_PER_NET(ctl_table, unix_table[]) = {
 	{
 		.ctl_name	= NET_UNIX_MAX_DGRAM_QLEN,
 		.procname	= "max_dgram_qlen",
-		.data		= &sysctl_unix_max_dgram_qlen,
+		.data		= &__per_net_base(sysctl_unix_max_dgram_qlen),
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec
@@ -26,35 +26,37 @@ static ctl_table unix_table[] = {
 	{ .ctl_name = 0 }
 };
 
-static ctl_table unix_net_table[] = {
+static DEFINE_PER_NET(ctl_table, unix_net_table[]) = {
 	{
 		.ctl_name	= NET_UNIX,
 		.procname	= "unix",
 		.mode		= 0555,
-		.child		= unix_table
+		.child		= __per_net_base(unix_table)
 	},
 	{ .ctl_name = 0 }
 };
 
-static ctl_table unix_root_table[] = {
+static DEFINE_PER_NET(ctl_table, unix_root_table[]) = {
 	{
 		.ctl_name	= CTL_NET,
 		.procname	= "net",
 		.mode		= 0555,
-		.child		= unix_net_table
+		.child		= __per_net_base(unix_net_table)
 	},
 	{ .ctl_name = 0 }
 };
 
-static struct ctl_table_header * unix_sysctl_header;
+static DEFINE_PER_NET(struct ctl_table_header *, unix_sysctl_header);
 
-void unix_sysctl_register(void)
+void unix_sysctl_register(net_t net)
 {
-	unix_sysctl_header = register_sysctl_table(unix_root_table);
+	ctl_table *table = per_net(unix_root_table, net);
+	per_net(unix_sysctl_header, net) = 
+		register_net_sysctl_table(net, table);
 }
 
-void unix_sysctl_unregister(void)
+void unix_sysctl_unregister(net_t net)
 {
-	unregister_sysctl_table(unix_sysctl_header);
+	unregister_net_sysctl_table(per_net(unix_sysctl_header, net));
 }
 
-- 
1.4.4.1.g278f