[deliverable/linux.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

extern int pty_limit;			/* Config limit on Unix98 ptys */
static DEFINE_IDR(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 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
 */

static struct dentry *get_node(int num)
{
	char s[12];
	struct dentry *root = devpts_root;
	mutex_lock(&root->d_inode->i_mutex);
	return lookup_one_len(s, root, sprintf(s, "%d", num));
}

int devpts_new_index(void)
{
	int index;
	int idr_ret;

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

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

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

void devpts_kill_index(int idx)
{
	mutex_lock(&allocated_ptys_lock);
	idr_remove(&allocated_ptys, idx);
	mutex_unlock(&allocated_ptys_lock);
}

int devpts_pty_new(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);

	/* 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;

	dentry = get_node(number);
	if (!IS_ERR(dentry) && !dentry->d_inode) {
		d_instantiate(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(int number)
{
	struct dentry *dentry = get_node(number);
	struct tty_struct *tty;

	tty = NULL;
	if (!IS_ERR(dentry)) {
		if (dentry->d_inode)
			tty = dentry->d_inode->i_private;
		dput(dentry);
	}

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

	return tty;
}

void devpts_pty_kill(int number)
{
	struct dentry *dentry = get_node(number);

	if (!IS_ERR(dentry)) {
		struct inode *inode = dentry->d_inode;
		if (inode) {
			inode->i_nlink--;
			d_delete(dentry);
			dput(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 MS	29	#define DEVPTS_DEFAULT_MODE 0600
b87a267e MS	30
718a9163 SB	31	extern int pty_limit; /* Config limit on Unix98 ptys */
	32	static DEFINE_IDR(allocated_ptys);
	33	static DEFINE_MUTEX(allocated_ptys_lock);
	34
1da177e4 LT	35	static struct vfsmount *devpts_mnt;
	36	static struct dentry *devpts_root;
	37
	38	static struct {
	39	int setuid;
	40	int setgid;
	41	uid_t uid;
	42	gid_t gid;
	43	umode_t mode;
b87a267e	44	} config = {.mode = DEVPTS_DEFAULT_MODE};
1da177e4	45
7a673c6b DP	46	enum {
	47	Opt_uid, Opt_gid, Opt_mode,
	48	Opt_err
	49	};
	50
	51	static match_table_t tokens = {
	52	{Opt_uid, "uid=%u"},
	53	{Opt_gid, "gid=%u"},
	54	{Opt_mode, "mode=%o"},
	55	{Opt_err, NULL}
	56	};
	57
1da177e4 LT	58	static int devpts_remount(struct super_block sb, int flags, char *data)
1da177e4 LT	59	{
7a673c6b DP	60	char *p;
	61
	62	config.setuid = 0;
	63	config.setgid = 0;
	64	config.uid = 0;
	65	config.gid = 0;
b87a267e	66	config.mode = DEVPTS_DEFAULT_MODE;
7a673c6b DP	67
	68	while ((p = strsep(&data, ",")) != NULL) {
	69	substring_t args[MAX_OPT_ARGS];
	70	int token;
	71	int option;
	72
	73	if (!*p)
1da177e4	74	continue;
7a673c6b DP	75
	76	token = match_token(p, tokens, args);
	77	switch (token) {
	78	case Opt_uid:
	79	if (match_int(&args[0], &option))
	80	return -EINVAL;
	81	config.uid = option;
	82	config.setuid = 1;
	83	break;
	84	case Opt_gid:
	85	if (match_int(&args[0], &option))
	86	return -EINVAL;
	87	config.gid = option;
	88	config.setgid = 1;
	89	break;
	90	case Opt_mode:
	91	if (match_octal(&args[0], &option))
	92	return -EINVAL;
b87a267e	93	config.mode = option & S_IALLUGO;
7a673c6b DP	94	break;
	95	default:
	96	printk(KERN_ERR "devpts: called with bogus options\n");
1da177e4 LT	97	return -EINVAL;
	98	}
	99	}
1da177e4 LT	100
	101	return 0;
	102	}
	103
b87a267e MS	104	static int devpts_show_options(struct seq_file seq, struct vfsmount vfs)
	105	{
	106	if (config.setuid)
	107	seq_printf(seq, ",uid=%u", config.uid);
	108	if (config.setgid)
	109	seq_printf(seq, ",gid=%u", config.gid);
	110	seq_printf(seq, ",mode=%03o", config.mode);
	111
	112	return 0;
	113	}
	114
ee9b6d61	115	static const struct super_operations devpts_sops = {
1da177e4 LT	116	.statfs = simple_statfs,
1da177e4 LT	117	.remount_fs = devpts_remount,
b87a267e	118	.show_options = devpts_show_options,
1da177e4 LT	119	};
	120
	121	static int
	122	devpts_fill_super(struct super_block s, void data, int silent)
	123	{
	124	struct inode * inode;
	125
	126	s->s_blocksize = 1024;
	127	s->s_blocksize_bits = 10;
	128	s->s_magic = DEVPTS_SUPER_MAGIC;
	129	s->s_op = &devpts_sops;
1da177e4 LT	130	s->s_time_gran = 1;
	131
	132	inode = new_inode(s);
	133	if (!inode)
	134	goto fail;
	135	inode->i_ino = 1;
	136	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	137	inode->i_blocks = 0;
1da177e4 LT	138	inode->i_uid = inode->i_gid = 0;
	139	inode->i_mode = S_IFDIR \| S_IRUGO \| S_IXUGO \| S_IWUSR;
	140	inode->i_op = &simple_dir_inode_operations;
	141	inode->i_fop = &simple_dir_operations;
	142	inode->i_nlink = 2;
	143
	144	devpts_root = s->s_root = d_alloc_root(inode);
	145	if (s->s_root)
	146	return 0;
	147
	148	printk("devpts: get root dentry failed\n");
	149	iput(inode);
	150	fail:
	151	return -ENOMEM;
	152	}
	153
454e2398 DH	154	static int devpts_get_sb(struct file_system_type *fs_type,
454e2398 DH	155	int flags, const char dev_name, void data, struct vfsmount *mnt)
1da177e4	156	{
454e2398	157	return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
1da177e4 LT	158	}
	159
	160	static struct file_system_type devpts_fs_type = {
	161	.owner = THIS_MODULE,
	162	.name = "devpts",
	163	.get_sb = devpts_get_sb,
	164	.kill_sb = kill_anon_super,
	165	};
	166
	167	/*
	168	* The normal naming convention is simply /dev/pts/<number>; this conforms
	169	* to the System V naming convention
	170	*/
	171
	172	static struct dentry *get_node(int num)
	173	{
	174	char s[12];
	175	struct dentry *root = devpts_root;
1b1dcc1b	176	mutex_lock(&root->d_inode->i_mutex);
1da177e4 LT	177	return lookup_one_len(s, root, sprintf(s, "%d", num));
	178	}
	179
718a9163 SB	180	int devpts_new_index(void)
	181	{
	182	int index;
	183	int idr_ret;
	184
	185	retry:
	186	if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
	187	return -ENOMEM;
	188	}
	189
	190	mutex_lock(&allocated_ptys_lock);
	191	idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
	192	if (idr_ret < 0) {
	193	mutex_unlock(&allocated_ptys_lock);
	194	if (idr_ret == -EAGAIN)
	195	goto retry;
	196	return -EIO;
	197	}
	198
	199	if (index >= pty_limit) {
	200	idr_remove(&allocated_ptys, index);
	201	mutex_unlock(&allocated_ptys_lock);
	202	return -EIO;
	203	}
	204	mutex_unlock(&allocated_ptys_lock);
	205	return index;
	206	}
	207
	208	void devpts_kill_index(int idx)
	209	{
	210	mutex_lock(&allocated_ptys_lock);
	211	idr_remove(&allocated_ptys, idx);
	212	mutex_unlock(&allocated_ptys_lock);
	213	}
	214
1da177e4 LT	215	int devpts_pty_new(struct tty_struct *tty)
1da177e4 LT	216	{
718a9163	217	int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
1da177e4 LT	218	struct tty_driver *driver = tty->driver;
	219	dev_t device = MKDEV(driver->major, driver->minor_start+number);
	220	struct dentry *dentry;
	221	struct inode *inode = new_inode(devpts_mnt->mnt_sb);
	222
	223	/* We're supposed to be given the slave end of a pty */
	224	BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
	225	BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
	226
	227	if (!inode)
	228	return -ENOMEM;
	229
	230	inode->i_ino = number+2;
1da177e4 LT	231	inode->i_uid = config.setuid ? config.uid : current->fsuid;
	232	inode->i_gid = config.setgid ? config.gid : current->fsgid;
	233	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	234	init_special_inode(inode, S_IFCHR\|config.mode, device);
8e18e294	235	inode->i_private = tty;
1da177e4 LT	236
1da177e4 LT	237	dentry = get_node(number);
3972b7f6	238	if (!IS_ERR(dentry) && !dentry->d_inode) {
1da177e4	239	d_instantiate(dentry, inode);
3972b7f6 FM	240	fsnotify_create(devpts_root->d_inode, dentry);
3972b7f6 FM	241	}
1da177e4	242
1b1dcc1b	243	mutex_unlock(&devpts_root->d_inode->i_mutex);
1da177e4 LT	244
	245	return 0;
	246	}
	247
	248	struct tty_struct *devpts_get_tty(int number)
	249	{
	250	struct dentry *dentry = get_node(number);
	251	struct tty_struct *tty;
	252
	253	tty = NULL;
	254	if (!IS_ERR(dentry)) {
	255	if (dentry->d_inode)
8e18e294	256	tty = dentry->d_inode->i_private;
1da177e4 LT	257	dput(dentry);
	258	}
	259
1b1dcc1b	260	mutex_unlock(&devpts_root->d_inode->i_mutex);
1da177e4 LT	261
	262	return tty;
	263	}
	264
	265	void devpts_pty_kill(int number)
	266	{
	267	struct dentry *dentry = get_node(number);
	268
	269	if (!IS_ERR(dentry)) {
	270	struct inode *inode = dentry->d_inode;
	271	if (inode) {
	272	inode->i_nlink--;
	273	d_delete(dentry);
	274	dput(dentry);
	275	}
	276	dput(dentry);
	277	}
1b1dcc1b	278	mutex_unlock(&devpts_root->d_inode->i_mutex);
1da177e4 LT	279	}
	280
	281	static int __init init_devpts_fs(void)
	282	{
	283	int err = register_filesystem(&devpts_fs_type);
	284	if (!err) {
	285	devpts_mnt = kern_mount(&devpts_fs_type);
	286	if (IS_ERR(devpts_mnt))
	287	err = PTR_ERR(devpts_mnt);
	288	}
	289	return err;
	290	}
	291
	292	static void __exit exit_devpts_fs(void)
	293	{
	294	unregister_filesystem(&devpts_fs_type);
	295	mntput(devpts_mnt);
	296	}
	297
	298	module_init(init_devpts_fs)
	299	module_exit(exit_devpts_fs)
	300	MODULE_LICENSE("GPL");