[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_MUTEX(allocated_ptys_lock);

static struct vfsmount *devpts_mnt;

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}
};

struct pts_fs_info {
	struct ida allocated_ptys;
};

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)
{
	if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
		return inode->i_sb;

	return devpts_mnt->mnt_sb;
}

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 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);

	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 free_fsi;
	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;

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

free_fsi:
	kfree(s->s_fs_info);
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 void devpts_kill_sb(struct super_block *sb)
{
	struct pts_fs_info *fsi = DEVPTS_SB(sb);

	kfree(fsi);
	kill_anon_super(sb);
}

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

/*
 * 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);
	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 >= pty_limit) {
		ida_remove(&fsi->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)
{
	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);
	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 super_block *sb = pts_sb_from_inode(ptmx_inode);
	struct inode *inode = new_inode(sb);
	struct dentry *root = sb->s_root;
	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(&root->d_inode->i_mutex);

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

	mutex_unlock(&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 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(&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(&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 */
718a9163 SB	33	static DEFINE_MUTEX(allocated_ptys_lock);
718a9163 SB	34
1da177e4	35	static struct vfsmount *devpts_mnt;
1da177e4 LT	36
	37	static struct {
	38	int setuid;
	39	int setgid;
	40	uid_t uid;
	41	gid_t gid;
	42	umode_t mode;
b87a267e	43	} config = {.mode = DEVPTS_DEFAULT_MODE};
1da177e4	44
7a673c6b DP	45	enum {
	46	Opt_uid, Opt_gid, Opt_mode,
	47	Opt_err
	48	};
	49
a447c093	50	static const match_table_t tokens = {
7a673c6b DP	51	{Opt_uid, "uid=%u"},
	52	{Opt_gid, "gid=%u"},
	53	{Opt_mode, "mode=%o"},
	54	{Opt_err, NULL}
	55	};
	56
e76b7c01 SB	57	struct pts_fs_info {
	58	struct ida allocated_ptys;
	59	};
	60
	61	static inline struct pts_fs_info DEVPTS_SB(struct super_block sb)
	62	{
	63	return sb->s_fs_info;
	64	}
	65
59e55e6c SB	66	static inline struct super_block pts_sb_from_inode(struct inode inode)
	67	{
	68	if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
	69	return inode->i_sb;
	70
	71	return devpts_mnt->mnt_sb;
	72	}
	73
1da177e4 LT	74	static int devpts_remount(struct super_block sb, int flags, char *data)
1da177e4 LT	75	{
7a673c6b DP	76	char *p;
	77
	78	config.setuid = 0;
	79	config.setgid = 0;
	80	config.uid = 0;
	81	config.gid = 0;
b87a267e	82	config.mode = DEVPTS_DEFAULT_MODE;
7a673c6b DP	83
	84	while ((p = strsep(&data, ",")) != NULL) {
	85	substring_t args[MAX_OPT_ARGS];
	86	int token;
	87	int option;
	88
	89	if (!*p)
1da177e4	90	continue;
7a673c6b DP	91
	92	token = match_token(p, tokens, args);
	93	switch (token) {
	94	case Opt_uid:
	95	if (match_int(&args[0], &option))
	96	return -EINVAL;
	97	config.uid = option;
	98	config.setuid = 1;
	99	break;
	100	case Opt_gid:
	101	if (match_int(&args[0], &option))
	102	return -EINVAL;
	103	config.gid = option;
	104	config.setgid = 1;
	105	break;
	106	case Opt_mode:
	107	if (match_octal(&args[0], &option))
	108	return -EINVAL;
b87a267e	109	config.mode = option & S_IALLUGO;
7a673c6b DP	110	break;
	111	default:
	112	printk(KERN_ERR "devpts: called with bogus options\n");
1da177e4 LT	113	return -EINVAL;
	114	}
	115	}
1da177e4 LT	116
	117	return 0;
	118	}
	119
b87a267e MS	120	static int devpts_show_options(struct seq_file seq, struct vfsmount vfs)
	121	{
	122	if (config.setuid)
	123	seq_printf(seq, ",uid=%u", config.uid);
	124	if (config.setgid)
	125	seq_printf(seq, ",gid=%u", config.gid);
	126	seq_printf(seq, ",mode=%03o", config.mode);
	127
	128	return 0;
	129	}
	130
ee9b6d61	131	static const struct super_operations devpts_sops = {
1da177e4 LT	132	.statfs = simple_statfs,
1da177e4 LT	133	.remount_fs = devpts_remount,
b87a267e	134	.show_options = devpts_show_options,
1da177e4 LT	135	};
1da177e4 LT	136
e76b7c01 SB	137	static void *new_pts_fs_info(void)
	138	{
	139	struct pts_fs_info *fsi;
	140
	141	fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
	142	if (!fsi)
	143	return NULL;
	144
	145	ida_init(&fsi->allocated_ptys);
	146
	147	return fsi;
	148	}
	149
1da177e4 LT	150	static int
	151	devpts_fill_super(struct super_block s, void data, int silent)
	152	{
	153	struct inode * inode;
	154
	155	s->s_blocksize = 1024;
	156	s->s_blocksize_bits = 10;
	157	s->s_magic = DEVPTS_SUPER_MAGIC;
	158	s->s_op = &devpts_sops;
1da177e4 LT	159	s->s_time_gran = 1;
1da177e4 LT	160
e76b7c01 SB	161	s->s_fs_info = new_pts_fs_info();
	162	if (!s->s_fs_info)
	163	goto fail;
	164
1da177e4 LT	165	inode = new_inode(s);
1da177e4 LT	166	if (!inode)
e76b7c01	167	goto free_fsi;
1da177e4 LT	168	inode->i_ino = 1;
	169	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	170	inode->i_blocks = 0;
1da177e4 LT	171	inode->i_uid = inode->i_gid = 0;
	172	inode->i_mode = S_IFDIR \| S_IRUGO \| S_IXUGO \| S_IWUSR;
	173	inode->i_op = &simple_dir_inode_operations;
	174	inode->i_fop = &simple_dir_operations;
	175	inode->i_nlink = 2;
	176
59e55e6c	177	s->s_root = d_alloc_root(inode);
1da177e4 LT	178	if (s->s_root)
	179	return 0;
	180
	181	printk("devpts: get root dentry failed\n");
	182	iput(inode);
e76b7c01 SB	183
	184	free_fsi:
	185	kfree(s->s_fs_info);
1da177e4 LT	186	fail:
	187	return -ENOMEM;
	188	}
	189
454e2398 DH	190	static int devpts_get_sb(struct file_system_type *fs_type,
454e2398 DH	191	int flags, const char dev_name, void data, struct vfsmount *mnt)
1da177e4	192	{
454e2398	193	return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
1da177e4 LT	194	}
1da177e4 LT	195
e76b7c01 SB	196	static void devpts_kill_sb(struct super_block *sb)
	197	{
	198	struct pts_fs_info *fsi = DEVPTS_SB(sb);
	199
	200	kfree(fsi);
	201	kill_anon_super(sb);
	202	}
	203
1da177e4 LT	204	static struct file_system_type devpts_fs_type = {
	205	.owner = THIS_MODULE,
	206	.name = "devpts",
	207	.get_sb = devpts_get_sb,
e76b7c01	208	.kill_sb = devpts_kill_sb,
1da177e4 LT	209	};
	210
	211	/*
	212	* The normal naming convention is simply /dev/pts/<number>; this conforms
	213	* to the System V naming convention
	214	*/
	215
15f1a633	216	int devpts_new_index(struct inode *ptmx_inode)
718a9163	217	{
e76b7c01 SB	218	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
e76b7c01 SB	219	struct pts_fs_info *fsi = DEVPTS_SB(sb);
718a9163	220	int index;
7ee7c12b	221	int ida_ret;
718a9163 SB	222
718a9163 SB	223	retry:
e76b7c01	224	if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) {
718a9163 SB	225	return -ENOMEM;
	226	}
	227
	228	mutex_lock(&allocated_ptys_lock);
e76b7c01	229	ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
7ee7c12b	230	if (ida_ret < 0) {
718a9163	231	mutex_unlock(&allocated_ptys_lock);
7ee7c12b	232	if (ida_ret == -EAGAIN)
718a9163 SB	233	goto retry;
	234	return -EIO;
	235	}
	236
	237	if (index >= pty_limit) {
e76b7c01	238	ida_remove(&fsi->allocated_ptys, index);
718a9163 SB	239	mutex_unlock(&allocated_ptys_lock);
	240	return -EIO;
	241	}
	242	mutex_unlock(&allocated_ptys_lock);
	243	return index;
	244	}
	245
15f1a633	246	void devpts_kill_index(struct inode *ptmx_inode, int idx)
718a9163	247	{
e76b7c01 SB	248	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
	249	struct pts_fs_info *fsi = DEVPTS_SB(sb);
	250
718a9163	251	mutex_lock(&allocated_ptys_lock);
e76b7c01	252	ida_remove(&fsi->allocated_ptys, idx);
718a9163 SB	253	mutex_unlock(&allocated_ptys_lock);
	254	}
	255
15f1a633	256	int devpts_pty_new(struct inode ptmx_inode, struct tty_struct tty)
1da177e4	257	{
718a9163	258	int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
1da177e4 LT	259	struct tty_driver *driver = tty->driver;
	260	dev_t device = MKDEV(driver->major, driver->minor_start+number);
	261	struct dentry *dentry;
59e55e6c SB	262	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
	263	struct inode *inode = new_inode(sb);
	264	struct dentry *root = sb->s_root;
89a52e10	265	char s[12];
1da177e4 LT	266
	267	/* We're supposed to be given the slave end of a pty */
	268	BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
	269	BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
	270
	271	if (!inode)
	272	return -ENOMEM;
	273
	274	inode->i_ino = number+2;
ec4c2aac DH	275	inode->i_uid = config.setuid ? config.uid : current_fsuid();
ec4c2aac DH	276	inode->i_gid = config.setgid ? config.gid : current_fsgid();
1da177e4 LT	277	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
1da177e4 LT	278	init_special_inode(inode, S_IFCHR\|config.mode, device);
8e18e294	279	inode->i_private = tty;
a6f37daa	280	tty->driver_data = inode;
1da177e4	281
89a52e10 SB	282	sprintf(s, "%d", number);
89a52e10 SB	283
59e55e6c	284	mutex_lock(&root->d_inode->i_mutex);
89a52e10	285
59e55e6c	286	dentry = d_alloc_name(root, s);
89a52e10 SB	287	if (!IS_ERR(dentry)) {
89a52e10 SB	288	d_add(dentry, inode);
59e55e6c	289	fsnotify_create(root->d_inode, dentry);
3972b7f6	290	}
1da177e4	291
59e55e6c	292	mutex_unlock(&root->d_inode->i_mutex);
1da177e4 LT	293
	294	return 0;
	295	}
	296
15f1a633	297	struct tty_struct devpts_get_tty(struct inode pts_inode, int number)
1da177e4	298	{
527b3e47	299	BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
1da177e4	300
527b3e47 SB	301	if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
	302	return (struct tty_struct *)pts_inode->i_private;
	303	return NULL;
1da177e4 LT	304	}
1da177e4 LT	305
15f1a633	306	void devpts_pty_kill(struct tty_struct *tty)
1da177e4	307	{
a6f37daa	308	struct inode *inode = tty->driver_data;
59e55e6c SB	309	struct super_block *sb = pts_sb_from_inode(inode);
59e55e6c SB	310	struct dentry *root = sb->s_root;
a6f37daa	311	struct dentry *dentry;
1da177e4	312
a6f37daa SB	313	BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
a6f37daa SB	314
59e55e6c	315	mutex_lock(&root->d_inode->i_mutex);
a6f37daa SB	316
	317	dentry = d_find_alias(inode);
	318	if (dentry && !IS_ERR(dentry)) {
	319	inode->i_nlink--;
	320	d_delete(dentry);
1da177e4 LT	321	dput(dentry);
1da177e4 LT	322	}
a6f37daa	323
59e55e6c	324	mutex_unlock(&root->d_inode->i_mutex);
1da177e4 LT	325	}
	326
	327	static int __init init_devpts_fs(void)
	328	{
	329	int err = register_filesystem(&devpts_fs_type);
	330	if (!err) {
	331	devpts_mnt = kern_mount(&devpts_fs_type);
	332	if (IS_ERR(devpts_mnt))
	333	err = PTR_ERR(devpts_mnt);
	334	}
	335	return err;
	336	}
	337
	338	static void __exit exit_devpts_fs(void)
	339	{
	340	unregister_filesystem(&devpts_fs_type);
	341	mntput(devpts_mnt);
	342	}
	343
	344	module_init(init_devpts_fs)
	345	module_exit(exit_devpts_fs)
	346	MODULE_LICENSE("GPL");