1 files changed, 71 insertions, 36 deletions

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 14afbabe654..cfe8466f7fe 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -10,6 +10,8 @@
  *
  * ------------------------------------------------------------------------- */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/fs.h>
@@ -148,10 +150,10 @@ static inline struct super_block *pts_sb_from_inode(struct inode *inode)
 
 /*
  * parse_mount_options():
- * 	Set @opts to mount options specified in @data. If an option is not
- * 	specified in @data, set it to its default value. The exception is
- * 	'newinstance' option which can only be set/cleared on a mount (i.e.
- * 	cannot be changed during remount).
+ *	Set @opts to mount options specified in @data. If an option is not
+ *	specified in @data, set it to its default value. The exception is
+ *	'newinstance' option which can only be set/cleared on a mount (i.e.
+ *	cannot be changed during remount).
  *
  * Note: @data may be NULL (in which case all options are set to default).
  */
@@ -225,7 +227,7 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
 			break;
 #endif
 		default:
-			printk(KERN_ERR "devpts: called with bogus options\n");
+			pr_err("called with bogus options\n");
 			return -EINVAL;
 		}
 	}
@@ -243,6 +245,13 @@ static int mknod_ptmx(struct super_block *sb)
 	struct dentry *root = sb->s_root;
 	struct pts_fs_info *fsi = DEVPTS_SB(sb);
 	struct pts_mount_opts *opts = &fsi->mount_opts;
+	kuid_t root_uid;
+	kgid_t root_gid;
+
+	root_uid = make_kuid(current_user_ns(), 0);
+	root_gid = make_kgid(current_user_ns(), 0);
+	if (!uid_valid(root_uid) || !gid_valid(root_gid))
+		return -EINVAL;
 
 	mutex_lock(&root->d_inode->i_mutex);
 
@@ -254,7 +263,7 @@ static int mknod_ptmx(struct super_block *sb)
 
 	dentry = d_alloc_name(root, "ptmx");
 	if (!dentry) {
-		printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n");
+		pr_err("Unable to alloc dentry for ptmx node\n");
 		goto out;
 	}
 
@@ -263,7 +272,7 @@ static int mknod_ptmx(struct super_block *sb)
 	 */
 	inode = new_inode(sb);
 	if (!inode) {
-		printk(KERN_ERR "Unable to alloc inode for ptmx node\n");
+		pr_err("Unable to alloc inode for ptmx node\n");
 		dput(dentry);
 		goto out;
 	}
@@ -273,6 +282,8 @@ static int mknod_ptmx(struct super_block *sb)
 
 	mode = S_IFCHR|opts->ptmxmode;
 	init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
+	inode->i_uid = root_uid;
+	inode->i_gid = root_gid;
 
 	d_add(dentry, inode);
 
@@ -294,7 +305,7 @@ static void update_ptmx_mode(struct pts_fs_info *fsi)
 #else
 static inline void update_ptmx_mode(struct pts_fs_info *fsi)
 {
-       return;
+	return;
 }
 #endif
 
@@ -304,6 +315,7 @@ static int devpts_remount(struct super_block *sb, int *flags, char *data)
 	struct pts_fs_info *fsi = DEVPTS_SB(sb);
 	struct pts_mount_opts *opts = &fsi->mount_opts;
 
+	sync_filesystem(sb);
 	err = parse_mount_options(data, PARSE_REMOUNT, opts);
 
 	/*
@@ -323,9 +335,11 @@ static int devpts_show_options(struct seq_file *seq, struct dentry *root)
 	struct pts_mount_opts *opts = &fsi->mount_opts;
 
 	if (opts->setuid)
-		seq_printf(seq, ",uid=%u", from_kuid_munged(&init_user_ns, opts->uid));
+		seq_printf(seq, ",uid=%u",
+			   from_kuid_munged(&init_user_ns, opts->uid));
 	if (opts->setgid)
-		seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, opts->gid));
+		seq_printf(seq, ",gid=%u",
+			   from_kgid_munged(&init_user_ns, opts->gid));
 	seq_printf(seq, ",mode=%03o", opts->mode);
 #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
 	seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
@@ -386,7 +400,7 @@ devpts_fill_super(struct super_block *s, void *data, int silent)
 	if (s->s_root)
 		return 0;
 
-	printk(KERN_ERR "devpts: get root dentry failed\n");
+	pr_err("get root dentry failed\n");
 
 fail:
 	return -ENOMEM;
@@ -438,6 +452,12 @@ static struct dentry *devpts_mount(struct file_system_type *fs_type,
 	if (error)
 		return ERR_PTR(error);
 
+	/* Require newinstance for all user namespace mounts to ensure
+	 * the mount options are not changed.
+	 */
+	if ((current_user_ns() != &init_user_ns) && !opts.newinstance)
+		return ERR_PTR(-EINVAL);
+
 	if (opts.newinstance)
 		s = sget(fs_type, NULL, set_anon_super, flags, NULL);
 	else
@@ -483,6 +503,7 @@ static void devpts_kill_sb(struct super_block *sb)
 {
 	struct pts_fs_info *fsi = DEVPTS_SB(sb);
 
+	ida_destroy(&fsi->allocated_ptys);
 	kfree(fsi);
 	kill_litter_super(sb);
 }
@@ -491,6 +512,9 @@ static struct file_system_type devpts_fs_type = {
 	.name		= "devpts",
 	.mount		= devpts_mount,
 	.kill_sb	= devpts_kill_sb,
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+	.fs_flags	= FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT,
+#endif
 };
 
 /*
@@ -545,37 +569,38 @@ void devpts_kill_index(struct inode *ptmx_inode, int idx)
 	mutex_unlock(&allocated_ptys_lock);
 }
 
-int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
+/**
+ * devpts_pty_new -- create a new inode in /dev/pts/
+ * @ptmx_inode: inode of the master
+ * @device: major+minor of the node to be created
+ * @index: used as a name of the node
+ * @priv: what's given back by devpts_get_priv
+ *
+ * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill.
+ */
+struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index,
+		void *priv)
 {
-	/* tty layer puts index from devpts_new_index() in here */
-	int number = tty->index;
-	struct tty_driver *driver = tty->driver;
-	dev_t device = MKDEV(driver->major, driver->minor_start+number);
 	struct dentry *dentry;
 	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
-	struct inode *inode = new_inode(sb);
+	struct inode *inode;
 	struct dentry *root = sb->s_root;
 	struct pts_fs_info *fsi = DEVPTS_SB(sb);
 	struct pts_mount_opts *opts = &fsi->mount_opts;
-	int ret = 0;
 	char s[12];
 
-	/* We're supposed to be given the slave end of a pty */
-	BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
-	BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
-
+	inode = new_inode(sb);
 	if (!inode)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
-	inode->i_ino = number + 3;
+	inode->i_ino = index + 3;
 	inode->i_uid = opts->setuid ? opts->uid : current_fsuid();
 	inode->i_gid = opts->setgid ? opts->gid : current_fsgid();
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	init_special_inode(inode, S_IFCHR|opts->mode, device);
-	inode->i_private = tty;
-	tty->driver_data = inode;
+	inode->i_private = priv;
 
-	sprintf(s, "%d", number);
+	sprintf(s, "%d", index);
 
 	mutex_lock(&root->d_inode->i_mutex);
 
@@ -585,18 +610,24 @@ int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
 		fsnotify_create(root->d_inode, dentry);
 	} else {
 		iput(inode);
-		ret = -ENOMEM;
+		inode = ERR_PTR(-ENOMEM);
 	}
 
 	mutex_unlock(&root->d_inode->i_mutex);
 
-	return ret;
+	return inode;
 }
 
-struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
+/**
+ * devpts_get_priv -- get private data for a slave
+ * @pts_inode: inode of the slave
+ *
+ * Returns whatever was passed as priv in devpts_pty_new for a given inode.
+ */
+void *devpts_get_priv(struct inode *pts_inode)
 {
 	struct dentry *dentry;
-	struct tty_struct *tty;
+	void *priv = NULL;
 
 	BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
 
@@ -605,18 +636,22 @@ struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
 	if (!dentry)
 		return NULL;
 
-	tty = NULL;
 	if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
-		tty = (struct tty_struct *)pts_inode->i_private;
+		priv = pts_inode->i_private;
 
 	dput(dentry);
 
-	return tty;
+	return priv;
 }
 
-void devpts_pty_kill(struct tty_struct *tty)
+/**
+ * devpts_pty_kill -- remove inode form /dev/pts/
+ * @inode: inode of the slave to be removed
+ *
+ * This is an inverse operation of devpts_pty_new.
+ */
+void devpts_pty_kill(struct inode *inode)
 {
-	struct inode *inode = tty->driver_data;
 	struct super_block *sb = pts_sb_from_inode(inode);
 	struct dentry *root = sb->s_root;
 	struct dentry *dentry;