[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>

1 files changed, 92 insertions, 26 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 060bba4567d2..ecad42b72ad6 100644
--- a/net/unix/af_unix.c
+++ b/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);