Initial import

1 files changed, 689 insertions, 0 deletions

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
new file mode 100644
index 000000000..add566303
--- /dev/null
+++ b/fs/devpts/inode.c
@@ -0,0 +1,689 @@
+/* -*- linux-c -*- --------------------------------------------------------- *
+ *
+ * linux/fs/devpts/inode.c
+ *
+ *  Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * ------------------------------------------------------------------------- */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/namei.h>
+#include <linux/slab.h>
+#include <linux/mount.h>
+#include <linux/tty.h>
+#include <linux/mutex.h>
+#include <linux/magic.h>
+#include <linux/idr.h>
+#include <linux/devpts_fs.h>
+#include <linux/parser.h>
+#include <linux/fsnotify.h>
+#include <linux/seq_file.h>
+
+#define DEVPTS_DEFAULT_MODE 0600
+/*
+ * ptmx is a new node in /dev/pts and will be unused in legacy (single-
+ * instance) mode. To prevent surprises in user space, set permissions of
+ * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful
+ * permissions.
+ */
+#define DEVPTS_DEFAULT_PTMX_MODE 0000
+#define PTMX_MINOR	2
+
+/*
+ * sysctl support for setting limits on the number of Unix98 ptys allocated.
+ * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
+ */
+static int pty_limit = NR_UNIX98_PTY_DEFAULT;
+static int pty_reserve = NR_UNIX98_PTY_RESERVE;
+static int pty_limit_min;
+static int pty_limit_max = INT_MAX;
+static int pty_count;
+
+static struct ctl_table pty_table[] = {
+	{
+		.procname	= "max",
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.data		= &pty_limit,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &pty_limit_min,
+		.extra2		= &pty_limit_max,
+	}, {
+		.procname	= "reserve",
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.data		= &pty_reserve,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &pty_limit_min,
+		.extra2		= &pty_limit_max,
+	}, {
+		.procname	= "nr",
+		.maxlen		= sizeof(int),
+		.mode		= 0444,
+		.data		= &pty_count,
+		.proc_handler	= proc_dointvec,
+	},
+	{}
+};
+
+static struct ctl_table pty_kern_table[] = {
+	{
+		.procname	= "pty",
+		.mode		= 0555,
+		.child		= pty_table,
+	},
+	{}
+};
+
+static struct ctl_table pty_root_table[] = {
+	{
+		.procname	= "kernel",
+		.mode		= 0555,
+		.child		= pty_kern_table,
+	},
+	{}
+};
+
+static DEFINE_MUTEX(allocated_ptys_lock);
+
+static struct vfsmount *devpts_mnt;
+
+struct pts_mount_opts {
+	int setuid;
+	int setgid;
+	kuid_t   uid;
+	kgid_t   gid;
+	umode_t mode;
+	umode_t ptmxmode;
+	int newinstance;
+	int max;
+};
+
+enum {
+	Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance,  Opt_max,
+	Opt_err
+};
+
+static const match_table_t tokens = {
+	{Opt_uid, "uid=%u"},
+	{Opt_gid, "gid=%u"},
+	{Opt_mode, "mode=%o"},
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+	{Opt_ptmxmode, "ptmxmode=%o"},
+	{Opt_newinstance, "newinstance"},
+	{Opt_max, "max=%d"},
+#endif
+	{Opt_err, NULL}
+};
+
+struct pts_fs_info {
+	struct ida allocated_ptys;
+	struct pts_mount_opts mount_opts;
+	struct dentry *ptmx_dentry;
+};
+
+static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+static inline struct super_block *pts_sb_from_inode(struct inode *inode)
+{
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+	if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
+		return inode->i_sb;
+#endif
+	return devpts_mnt->mnt_sb;
+}
+
+#define PARSE_MOUNT	0
+#define PARSE_REMOUNT	1
+
+/*
+ * 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).
+ *
+ * Note: @data may be NULL (in which case all options are set to default).
+ */
+static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
+{
+	char *p;
+	kuid_t uid;
+	kgid_t gid;
+
+	opts->setuid  = 0;
+	opts->setgid  = 0;
+	opts->uid     = GLOBAL_ROOT_UID;
+	opts->gid     = GLOBAL_ROOT_GID;
+	opts->mode    = DEVPTS_DEFAULT_MODE;
+	opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
+	opts->max     = NR_UNIX98_PTY_MAX;
+
+	/* newinstance makes sense only on initial mount */
+	if (op == PARSE_MOUNT)
+		opts->newinstance = 0;
+
+	while ((p = strsep(&data, ",")) != NULL) {
+		substring_t args[MAX_OPT_ARGS];
+		int token;
+		int option;
+
+		if (!*p)
+			continue;
+
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case Opt_uid:
+			if (match_int(&args[0], &option))
+				return -EINVAL;
+			uid = make_kuid(current_user_ns(), option);
+			if (!uid_valid(uid))
+				return -EINVAL;
+			opts->uid = uid;
+			opts->setuid = 1;
+			break;
+		case Opt_gid:
+			if (match_int(&args[0], &option))
+				return -EINVAL;
+			gid = make_kgid(current_user_ns(), option);
+			if (!gid_valid(gid))
+				return -EINVAL;
+			opts->gid = gid;
+			opts->setgid = 1;
+			break;
+		case Opt_mode:
+			if (match_octal(&args[0], &option))
+				return -EINVAL;
+			opts->mode = option & S_IALLUGO;
+			break;
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+		case Opt_ptmxmode:
+			if (match_octal(&args[0], &option))
+				return -EINVAL;
+			opts->ptmxmode = option & S_IALLUGO;
+			break;
+		case Opt_newinstance:
+			/* newinstance makes sense only on initial mount */
+			if (op == PARSE_MOUNT)
+				opts->newinstance = 1;
+			break;
+		case Opt_max:
+			if (match_int(&args[0], &option) ||
+			    option < 0 || option > NR_UNIX98_PTY_MAX)
+				return -EINVAL;
+			opts->max = option;
+			break;
+#endif
+		default:
+			pr_err("called with bogus options\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+static int mknod_ptmx(struct super_block *sb)
+{
+	int mode;
+	int rc = -ENOMEM;
+	struct dentry *dentry;
+	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;
+	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(&d_inode(root)->i_mutex);
+
+	/* If we have already created ptmx node, return */
+	if (fsi->ptmx_dentry) {
+		rc = 0;
+		goto out;
+	}
+
+	dentry = d_alloc_name(root, "ptmx");
+	if (!dentry) {
+		pr_err("Unable to alloc dentry for ptmx node\n");
+		goto out;
+	}
+
+	/*
+	 * Create a new 'ptmx' node in this mount of devpts.
+	 */
+	inode = new_inode(sb);
+	if (!inode) {
+		pr_err("Unable to alloc inode for ptmx node\n");
+		dput(dentry);
+		goto out;
+	}
+
+	inode->i_ino = 2;
+	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+
+	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);
+
+	fsi->ptmx_dentry = dentry;
+	rc = 0;
+out:
+	mutex_unlock(&d_inode(root)->i_mutex);
+	return rc;
+}
+
+static void update_ptmx_mode(struct pts_fs_info *fsi)
+{
+	struct inode *inode;
+	if (fsi->ptmx_dentry) {
+		inode = d_inode(fsi->ptmx_dentry);
+		inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode;
+	}
+}
+#else
+static inline void update_ptmx_mode(struct pts_fs_info *fsi)
+{
+	return;
+}
+#endif
+
+static int devpts_remount(struct super_block *sb, int *flags, char *data)
+{
+	int err;
+	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);
+
+	/*
+	 * parse_mount_options() restores options to default values
+	 * before parsing and may have changed ptmxmode. So, update the
+	 * mode in the inode too. Bogus options don't fail the remount,
+	 * so do this even on error return.
+	 */
+	update_ptmx_mode(fsi);
+
+	return err;
+}
+
+static int devpts_show_options(struct seq_file *seq, struct dentry *root)
+{
+	struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb);
+	struct pts_mount_opts *opts = &fsi->mount_opts;
+
+	if (opts->setuid)
+		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, ",mode=%03o", opts->mode);
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+	seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
+	if (opts->max < NR_UNIX98_PTY_MAX)
+		seq_printf(seq, ",max=%d", opts->max);
+#endif
+
+	return 0;
+}
+
+static const struct super_operations devpts_sops = {
+	.statfs		= simple_statfs,
+	.remount_fs	= devpts_remount,
+	.show_options	= devpts_show_options,
+};
+
+static void *new_pts_fs_info(void)
+{
+	struct pts_fs_info *fsi;
+
+	fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
+	if (!fsi)
+		return NULL;
+
+	ida_init(&fsi->allocated_ptys);
+	fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE;
+	fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
+
+	return fsi;
+}
+
+static int
+devpts_fill_super(struct super_block *s, void *data, int silent)
+{
+	struct inode *inode;
+
+	s->s_blocksize = 1024;
+	s->s_blocksize_bits = 10;
+	s->s_magic = DEVPTS_SUPER_MAGIC;
+	s->s_op = &devpts_sops;
+	s->s_time_gran = 1;
+
+	s->s_fs_info = new_pts_fs_info();
+	if (!s->s_fs_info)
+		goto fail;
+
+	inode = new_inode(s);
+	if (!inode)
+		goto fail;
+	inode->i_ino = 1;
+	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+	inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
+	inode->i_op = &simple_dir_inode_operations;
+	inode->i_fop = &simple_dir_operations;
+	set_nlink(inode, 2);
+
+	s->s_root = d_make_root(inode);
+	if (s->s_root)
+		return 0;
+
+	pr_err("get root dentry failed\n");
+
+fail:
+	return -ENOMEM;
+}
+
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+static int compare_init_pts_sb(struct super_block *s, void *p)
+{
+	if (devpts_mnt)
+		return devpts_mnt->mnt_sb == s;
+	return 0;
+}
+
+/*
+ * devpts_mount()
+ *
+ *     If the '-o newinstance' mount option was specified, mount a new
+ *     (private) instance of devpts.  PTYs created in this instance are
+ *     independent of the PTYs in other devpts instances.
+ *
+ *     If the '-o newinstance' option was not specified, mount/remount the
+ *     initial kernel mount of devpts.  This type of mount gives the
+ *     legacy, single-instance semantics.
+ *
+ *     The 'newinstance' option is needed to support multiple namespace
+ *     semantics in devpts while preserving backward compatibility of the
+ *     current 'single-namespace' semantics. i.e all mounts of devpts
+ *     without the 'newinstance' mount option should bind to the initial
+ *     kernel mount, like mount_single().
+ *
+ *     Mounts with 'newinstance' option create a new, private namespace.
+ *
+ *     NOTE:
+ *
+ *     For single-mount semantics, devpts cannot use mount_single(),
+ *     because mount_single()/sget() find and use the super-block from
+ *     the most recent mount of devpts. But that recent mount may be a
+ *     'newinstance' mount and mount_single() would pick the newinstance
+ *     super-block instead of the initial super-block.
+ */
+static struct dentry *devpts_mount(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data)
+{
+	int error;
+	struct pts_mount_opts opts;
+	struct super_block *s;
+
+	error = parse_mount_options(data, PARSE_MOUNT, &opts);
+	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
+		s = sget(fs_type, compare_init_pts_sb, set_anon_super, flags,
+			 NULL);
+
+	if (IS_ERR(s))
+		return ERR_CAST(s);
+
+	if (!s->s_root) {
+		error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
+		if (error)
+			goto out_undo_sget;
+		s->s_flags |= MS_ACTIVE;
+	}
+
+	memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts));
+
+	error = mknod_ptmx(s);
+	if (error)
+		goto out_undo_sget;
+
+	return dget(s->s_root);
+
+out_undo_sget:
+	deactivate_locked_super(s);
+	return ERR_PTR(error);
+}
+
+#else
+/*
+ * This supports only the legacy single-instance semantics (no
+ * multiple-instance semantics)
+ */
+static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags,
+		const char *dev_name, void *data)
+{
+	return mount_single(fs_type, flags, data, devpts_fill_super);
+}
+#endif
+
+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);
+}
+
+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
+};
+
+/*
+ * The normal naming convention is simply /dev/pts/<number>; this conforms
+ * to the System V naming convention
+ */
+
+int devpts_new_index(struct inode *ptmx_inode)
+{
+	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+	struct pts_fs_info *fsi = DEVPTS_SB(sb);
+	int index;
+	int ida_ret;
+
+retry:
+	if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
+		return -ENOMEM;
+
+	mutex_lock(&allocated_ptys_lock);
+	if (pty_count >= pty_limit -
+			(fsi->mount_opts.newinstance ? pty_reserve : 0)) {
+		mutex_unlock(&allocated_ptys_lock);
+		return -ENOSPC;
+	}
+
+	ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
+	if (ida_ret < 0) {
+		mutex_unlock(&allocated_ptys_lock);
+		if (ida_ret == -EAGAIN)
+			goto retry;
+		return -EIO;
+	}
+
+	if (index >= fsi->mount_opts.max) {
+		ida_remove(&fsi->allocated_ptys, index);
+		mutex_unlock(&allocated_ptys_lock);
+		return -ENOSPC;
+	}
+	pty_count++;
+	mutex_unlock(&allocated_ptys_lock);
+	return index;
+}
+
+void devpts_kill_index(struct inode *ptmx_inode, int idx)
+{
+	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+	struct pts_fs_info *fsi = DEVPTS_SB(sb);
+
+	mutex_lock(&allocated_ptys_lock);
+	ida_remove(&fsi->allocated_ptys, idx);
+	pty_count--;
+	mutex_unlock(&allocated_ptys_lock);
+}
+
+/**
+ * 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)
+{
+	struct dentry *dentry;
+	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+	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;
+	char s[12];
+
+	inode = new_inode(sb);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	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 = priv;
+
+	sprintf(s, "%d", index);
+
+	mutex_lock(&d_inode(root)->i_mutex);
+
+	dentry = d_alloc_name(root, s);
+	if (dentry) {
+		d_add(dentry, inode);
+		fsnotify_create(d_inode(root), dentry);
+	} else {
+		iput(inode);
+		inode = ERR_PTR(-ENOMEM);
+	}
+
+	mutex_unlock(&d_inode(root)->i_mutex);
+
+	return inode;
+}
+
+/**
+ * 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;
+	void *priv = NULL;
+
+	BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
+
+	/* Ensure dentry has not been deleted by devpts_pty_kill() */
+	dentry = d_find_alias(pts_inode);
+	if (!dentry)
+		return NULL;
+
+	if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
+		priv = pts_inode->i_private;
+
+	dput(dentry);
+
+	return priv;
+}
+
+/**
+ * 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 super_block *sb = pts_sb_from_inode(inode);
+	struct dentry *root = sb->s_root;
+	struct dentry *dentry;
+
+	BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
+
+	mutex_lock(&d_inode(root)->i_mutex);
+
+	dentry = d_find_alias(inode);
+
+	drop_nlink(inode);
+	d_delete(dentry);
+	dput(dentry);	/* d_alloc_name() in devpts_pty_new() */
+	dput(dentry);		/* d_find_alias above */
+
+	mutex_unlock(&d_inode(root)->i_mutex);
+}
+
+static int __init init_devpts_fs(void)
+{
+	int err = register_filesystem(&devpts_fs_type);
+	struct ctl_table_header *table;
+
+	if (!err) {
+		table = register_sysctl_table(pty_root_table);
+		devpts_mnt = kern_mount(&devpts_fs_type);
+		if (IS_ERR(devpts_mnt)) {
+			err = PTR_ERR(devpts_mnt);
+			unregister_filesystem(&devpts_fs_type);
+			unregister_sysctl_table(table);
+		}
+	}
+	return err;
+}
+module_init(init_devpts_fs)