[linux-2.6-block.git] / fs / devpts / inode.c

/* -*- 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.
 *
 * ------------------------------------------------------------------------- */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/tty.h>
#include <linux/mutex.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_SUPER_MAGIC 0x1cd1

#define DEVPTS_DEFAULT_MODE 0600
#define PTMX_MINOR	2

extern int pty_limit;			/* Config limit on Unix98 ptys */
static DEFINE_IDA(allocated_ptys);
static DEFINE_MUTEX(allocated_ptys_lock);

static struct vfsmount *devpts_mnt;
static struct dentry *devpts_root;

static struct {
	int setuid;
	int setgid;
	uid_t   uid;
	gid_t   gid;
	umode_t mode;
} config = {.mode = DEVPTS_DEFAULT_MODE};

enum {
	Opt_uid, Opt_gid, Opt_mode,
	Opt_err
};

static const match_table_t tokens = {
	{Opt_uid, "uid=%u"},
	{Opt_gid, "gid=%u"},
	{Opt_mode, "mode=%o"},
	{Opt_err, NULL}
};

static int devpts_remount(struct super_block *sb, int *flags, char *data)
{
	char *p;

	config.setuid  = 0;
	config.setgid  = 0;
	config.uid     = 0;
	config.gid     = 0;
	config.mode    = DEVPTS_DEFAULT_MODE;

	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;
			config.uid = option;
			config.setuid = 1;
			break;
		case Opt_gid:
			if (match_int(&args[0], &option))
				return -EINVAL;
			config.gid = option;
			config.setgid = 1;
			break;
		case Opt_mode:
			if (match_octal(&args[0], &option))
				return -EINVAL;
			config.mode = option & S_IALLUGO;
			break;
		default:
			printk(KERN_ERR "devpts: called with bogus options\n");
			return -EINVAL;
		}
	}

	return 0;
}

static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
{
	if (config.setuid)
		seq_printf(seq, ",uid=%u", config.uid);
	if (config.setgid)
		seq_printf(seq, ",gid=%u", config.gid);
	seq_printf(seq, ",mode=%03o", config.mode);

	return 0;
}

static const struct super_operations devpts_sops = {
	.statfs		= simple_statfs,
	.remount_fs	= devpts_remount,
	.show_options	= devpts_show_options,
};

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;

	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_blocks = 0;
	inode->i_uid = inode->i_gid = 0;
	inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
	inode->i_op = &simple_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	inode->i_nlink = 2;

	devpts_root = s->s_root = d_alloc_root(inode);
	if (s->s_root)
		return 0;
	
	printk("devpts: get root dentry failed\n");
	iput(inode);
fail:
	return -ENOMEM;
}

static int devpts_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
	return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
}

static struct file_system_type devpts_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "devpts",
	.get_sb		= devpts_get_sb,
	.kill_sb	= kill_anon_super,
};

/*
 * 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)
{
	int index;
	int ida_ret;

retry:
	if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) {
		return -ENOMEM;
	}

	mutex_lock(&allocated_ptys_lock);
	ida_ret = ida_get_new(&allocated_ptys, &index);
	if (ida_ret < 0) {
		mutex_unlock(&allocated_ptys_lock);
		if (ida_ret == -EAGAIN)
			goto retry;
		return -EIO;
	}

	if (index >= pty_limit) {
		ida_remove(&allocated_ptys, index);
		mutex_unlock(&allocated_ptys_lock);
		return -EIO;
	}
	mutex_unlock(&allocated_ptys_lock);
	return index;
}

void devpts_kill_index(struct inode *ptmx_inode, int idx)
{
	mutex_lock(&allocated_ptys_lock);
	ida_remove(&allocated_ptys, idx);
	mutex_unlock(&allocated_ptys_lock);
}

int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
{
	int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
	struct tty_driver *driver = tty->driver;
	dev_t device = MKDEV(driver->major, driver->minor_start+number);
	struct dentry *dentry;
	struct inode *inode = new_inode(devpts_mnt->mnt_sb);
	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);

	if (!inode)
		return -ENOMEM;

	inode->i_ino = number+2;
	inode->i_uid = config.setuid ? config.uid : current_fsuid();
	inode->i_gid = config.setgid ? config.gid : current_fsgid();
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	init_special_inode(inode, S_IFCHR|config.mode, device);
	inode->i_private = tty;
	tty->driver_data = inode;

	sprintf(s, "%d", number);

	mutex_lock(&devpts_root->d_inode->i_mutex);

	dentry = d_alloc_name(devpts_root, s);
	if (!IS_ERR(dentry)) {
		d_add(dentry, inode);
		fsnotify_create(devpts_root->d_inode, dentry);
	}

	mutex_unlock(&devpts_root->d_inode->i_mutex);

	return 0;
}

struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
{
	BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));

	if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
		return (struct tty_struct *)pts_inode->i_private;
	return NULL;
}

void devpts_pty_kill(struct tty_struct *tty)
{
	struct inode *inode = tty->driver_data;
	struct dentry *dentry;

	BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));

	mutex_lock(&devpts_root->d_inode->i_mutex);

	dentry = d_find_alias(inode);
	if (dentry && !IS_ERR(dentry)) {
		inode->i_nlink--;
		d_delete(dentry);
		dput(dentry);
	}

	mutex_unlock(&devpts_root->d_inode->i_mutex);
}

static int __init init_devpts_fs(void)
{
	int err = register_filesystem(&devpts_fs_type);
	if (!err) {
		devpts_mnt = kern_mount(&devpts_fs_type);
		if (IS_ERR(devpts_mnt))
			err = PTR_ERR(devpts_mnt);
	}
	return err;
}

static void __exit exit_devpts_fs(void)
{
	unregister_filesystem(&devpts_fs_type);
	mntput(devpts_mnt);
}

module_init(init_devpts_fs)
module_exit(exit_devpts_fs)
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/* -- linux-c -- --------------------------------------------------------- *
	2	*
	3	* linux/fs/devpts/inode.c
	4	*
	5	* Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
	6	*
	7	* This file is part of the Linux kernel and is made available under
	8	* the terms of the GNU General Public License, version 2, or at your
	9	* option, any later version, incorporated herein by reference.
	10	*
	11	* ------------------------------------------------------------------------- */
	12
	13	#include <linux/module.h>
	14	#include <linux/init.h>
	15	#include <linux/fs.h>
	16	#include <linux/sched.h>
	17	#include <linux/namei.h>
	18	#include <linux/mount.h>
	19	#include <linux/tty.h>
718a9163 SB	20	#include <linux/mutex.h>
718a9163 SB	21	#include <linux/idr.h>
1da177e4	22	#include <linux/devpts_fs.h>
7a673c6b	23	#include <linux/parser.h>
3972b7f6	24	#include <linux/fsnotify.h>
b87a267e	25	#include <linux/seq_file.h>
1da177e4 LT	26
	27	#define DEVPTS_SUPER_MAGIC 0x1cd1
	28
b87a267e	29	#define DEVPTS_DEFAULT_MODE 0600
527b3e47	30	#define PTMX_MINOR 2
b87a267e	31
718a9163	32	extern int pty_limit; /* Config limit on Unix98 ptys */
7ee7c12b	33	static DEFINE_IDA(allocated_ptys);
718a9163 SB	34	static DEFINE_MUTEX(allocated_ptys_lock);
718a9163 SB	35
1da177e4 LT	36	static struct vfsmount *devpts_mnt;
	37	static struct dentry *devpts_root;
	38
	39	static struct {
	40	int setuid;
	41	int setgid;
	42	uid_t uid;
	43	gid_t gid;
	44	umode_t mode;
b87a267e	45	} config = {.mode = DEVPTS_DEFAULT_MODE};
1da177e4	46
7a673c6b DP	47	enum {
	48	Opt_uid, Opt_gid, Opt_mode,
	49	Opt_err
	50	};
	51
a447c093	52	static const match_table_t tokens = {
7a673c6b DP	53	{Opt_uid, "uid=%u"},
	54	{Opt_gid, "gid=%u"},
	55	{Opt_mode, "mode=%o"},
	56	{Opt_err, NULL}
	57	};
	58
1da177e4 LT	59	static int devpts_remount(struct super_block sb, int flags, char *data)
1da177e4 LT	60	{
7a673c6b DP	61	char *p;
	62
	63	config.setuid = 0;
	64	config.setgid = 0;
	65	config.uid = 0;
	66	config.gid = 0;
b87a267e	67	config.mode = DEVPTS_DEFAULT_MODE;
7a673c6b DP	68
	69	while ((p = strsep(&data, ",")) != NULL) {
	70	substring_t args[MAX_OPT_ARGS];
	71	int token;
	72	int option;
	73
	74	if (!*p)
1da177e4	75	continue;
7a673c6b DP	76
	77	token = match_token(p, tokens, args);
	78	switch (token) {
	79	case Opt_uid:
	80	if (match_int(&args[0], &option))
	81	return -EINVAL;
	82	config.uid = option;
	83	config.setuid = 1;
	84	break;
	85	case Opt_gid:
	86	if (match_int(&args[0], &option))
	87	return -EINVAL;
	88	config.gid = option;
	89	config.setgid = 1;
	90	break;
	91	case Opt_mode:
	92	if (match_octal(&args[0], &option))
	93	return -EINVAL;
b87a267e	94	config.mode = option & S_IALLUGO;
7a673c6b DP	95	break;
	96	default:
	97	printk(KERN_ERR "devpts: called with bogus options\n");
1da177e4 LT	98	return -EINVAL;
	99	}
	100	}
1da177e4 LT	101
	102	return 0;
	103	}
	104
b87a267e MS	105	static int devpts_show_options(struct seq_file seq, struct vfsmount vfs)
	106	{
	107	if (config.setuid)
	108	seq_printf(seq, ",uid=%u", config.uid);
	109	if (config.setgid)
	110	seq_printf(seq, ",gid=%u", config.gid);
	111	seq_printf(seq, ",mode=%03o", config.mode);
	112
	113	return 0;
	114	}
	115
ee9b6d61	116	static const struct super_operations devpts_sops = {
1da177e4 LT	117	.statfs = simple_statfs,
1da177e4 LT	118	.remount_fs = devpts_remount,
b87a267e	119	.show_options = devpts_show_options,
1da177e4 LT	120	};
	121
	122	static int
	123	devpts_fill_super(struct super_block s, void data, int silent)
	124	{
	125	struct inode * inode;
	126
	127	s->s_blocksize = 1024;
	128	s->s_blocksize_bits = 10;
	129	s->s_magic = DEVPTS_SUPER_MAGIC;
	130	s->s_op = &devpts_sops;
1da177e4 LT	131	s->s_time_gran = 1;
	132
	133	inode = new_inode(s);
	134	if (!inode)
	135	goto fail;
	136	inode->i_ino = 1;
	137	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	138	inode->i_blocks = 0;
1da177e4 LT	139	inode->i_uid = inode->i_gid = 0;
	140	inode->i_mode = S_IFDIR \| S_IRUGO \| S_IXUGO \| S_IWUSR;
	141	inode->i_op = &simple_dir_inode_operations;
	142	inode->i_fop = &simple_dir_operations;
	143	inode->i_nlink = 2;
	144
	145	devpts_root = s->s_root = d_alloc_root(inode);
	146	if (s->s_root)
	147	return 0;
	148
	149	printk("devpts: get root dentry failed\n");
	150	iput(inode);
	151	fail:
	152	return -ENOMEM;
	153	}
	154
454e2398 DH	155	static int devpts_get_sb(struct file_system_type *fs_type,
454e2398 DH	156	int flags, const char dev_name, void data, struct vfsmount *mnt)
1da177e4	157	{
454e2398	158	return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
1da177e4 LT	159	}
	160
	161	static struct file_system_type devpts_fs_type = {
	162	.owner = THIS_MODULE,
	163	.name = "devpts",
	164	.get_sb = devpts_get_sb,
	165	.kill_sb = kill_anon_super,
	166	};
	167
	168	/*
	169	* The normal naming convention is simply /dev/pts/<number>; this conforms
	170	* to the System V naming convention
	171	*/
	172
15f1a633	173	int devpts_new_index(struct inode *ptmx_inode)
718a9163 SB	174	{
718a9163 SB	175	int index;
7ee7c12b	176	int ida_ret;
718a9163 SB	177
718a9163 SB	178	retry:
7ee7c12b	179	if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) {
718a9163 SB	180	return -ENOMEM;
	181	}
	182
	183	mutex_lock(&allocated_ptys_lock);
7ee7c12b AD	184	ida_ret = ida_get_new(&allocated_ptys, &index);
7ee7c12b AD	185	if (ida_ret < 0) {
718a9163	186	mutex_unlock(&allocated_ptys_lock);
7ee7c12b	187	if (ida_ret == -EAGAIN)
718a9163 SB	188	goto retry;
	189	return -EIO;
	190	}
	191
	192	if (index >= pty_limit) {
7ee7c12b	193	ida_remove(&allocated_ptys, index);
718a9163 SB	194	mutex_unlock(&allocated_ptys_lock);
	195	return -EIO;
	196	}
	197	mutex_unlock(&allocated_ptys_lock);
	198	return index;
	199	}
	200
15f1a633	201	void devpts_kill_index(struct inode *ptmx_inode, int idx)
718a9163 SB	202	{
718a9163 SB	203	mutex_lock(&allocated_ptys_lock);
7ee7c12b	204	ida_remove(&allocated_ptys, idx);
718a9163 SB	205	mutex_unlock(&allocated_ptys_lock);
	206	}
	207
15f1a633	208	int devpts_pty_new(struct inode ptmx_inode, struct tty_struct tty)
1da177e4	209	{
718a9163	210	int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
1da177e4 LT	211	struct tty_driver *driver = tty->driver;
	212	dev_t device = MKDEV(driver->major, driver->minor_start+number);
	213	struct dentry *dentry;
	214	struct inode *inode = new_inode(devpts_mnt->mnt_sb);
89a52e10	215	char s[12];
1da177e4 LT	216
	217	/* We're supposed to be given the slave end of a pty */
	218	BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
	219	BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
	220
	221	if (!inode)
	222	return -ENOMEM;
	223
	224	inode->i_ino = number+2;
ec4c2aac DH	225	inode->i_uid = config.setuid ? config.uid : current_fsuid();
ec4c2aac DH	226	inode->i_gid = config.setgid ? config.gid : current_fsgid();
1da177e4 LT	227	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
1da177e4 LT	228	init_special_inode(inode, S_IFCHR\|config.mode, device);
8e18e294	229	inode->i_private = tty;
a6f37daa	230	tty->driver_data = inode;
1da177e4	231
89a52e10 SB	232	sprintf(s, "%d", number);
	233
	234	mutex_lock(&devpts_root->d_inode->i_mutex);
	235
	236	dentry = d_alloc_name(devpts_root, s);
	237	if (!IS_ERR(dentry)) {
	238	d_add(dentry, inode);
3972b7f6 FM	239	fsnotify_create(devpts_root->d_inode, dentry);
3972b7f6 FM	240	}
1da177e4	241
1b1dcc1b	242	mutex_unlock(&devpts_root->d_inode->i_mutex);
1da177e4 LT	243
	244	return 0;
	245	}
	246
15f1a633	247	struct tty_struct devpts_get_tty(struct inode pts_inode, int number)
1da177e4	248	{
527b3e47	249	BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
1da177e4	250
527b3e47 SB	251	if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
	252	return (struct tty_struct *)pts_inode->i_private;
	253	return NULL;
1da177e4 LT	254	}
1da177e4 LT	255
15f1a633	256	void devpts_pty_kill(struct tty_struct *tty)
1da177e4	257	{
a6f37daa SB	258	struct inode *inode = tty->driver_data;
a6f37daa SB	259	struct dentry *dentry;
1da177e4	260
a6f37daa SB	261	BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
	262
	263	mutex_lock(&devpts_root->d_inode->i_mutex);
	264
	265	dentry = d_find_alias(inode);
	266	if (dentry && !IS_ERR(dentry)) {
	267	inode->i_nlink--;
	268	d_delete(dentry);
1da177e4 LT	269	dput(dentry);
1da177e4 LT	270	}
a6f37daa	271
1b1dcc1b	272	mutex_unlock(&devpts_root->d_inode->i_mutex);
1da177e4 LT	273	}
	274
	275	static int __init init_devpts_fs(void)
	276	{
	277	int err = register_filesystem(&devpts_fs_type);
	278	if (!err) {
	279	devpts_mnt = kern_mount(&devpts_fs_type);
	280	if (IS_ERR(devpts_mnt))
	281	err = PTR_ERR(devpts_mnt);
	282	}
	283	return err;
	284	}
	285
	286	static void __exit exit_devpts_fs(void)
	287	{
	288	unregister_filesystem(&devpts_fs_type);
	289	mntput(devpts_mnt);
	290	}
	291
	292	module_init(init_devpts_fs)
	293	module_exit(exit_devpts_fs)
	294	MODULE_LICENSE("GPL");