[net-next-2.6.git] / drivers / base / devtmpfs.c

/*
 * devtmpfs - kernel-maintained tmpfs-based /dev
 *
 * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
 *
 * During bootup, before any driver core device is registered,
 * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
 * device which requests a device node, will add a node in this
 * filesystem.
 * By default, all devices are named after the the name of the
 * device, owned by root and have a default mode of 0600. Subsystems
 * can overwrite the default setting if needed.
 */

#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/mount.h>
#include <linux/device.h>
#include <linux/genhd.h>
#include <linux/namei.h>
#include <linux/fs.h>
#include <linux/shmem_fs.h>
#include <linux/cred.h>
#include <linux/sched.h>
#include <linux/init_task.h>
#include <linux/slab.h>

static struct vfsmount *dev_mnt;

#if defined CONFIG_DEVTMPFS_MOUNT
static int dev_mount = 1;
#else
static int dev_mount;
#endif

static DEFINE_MUTEX(dirlock);

static int __init mount_param(char *str)
{
	dev_mount = simple_strtoul(str, NULL, 0);
	return 1;
}
__setup("devtmpfs.mount=", mount_param);

static int dev_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, shmem_fill_super, mnt);
}

static struct file_system_type dev_fs_type = {
	.name = "devtmpfs",
	.get_sb = dev_get_sb,
	.kill_sb = kill_litter_super,
};

#ifdef CONFIG_BLOCK
static inline int is_blockdev(struct device *dev)
{
	return dev->class == &block_class;
}
#else
static inline int is_blockdev(struct device *dev) { return 0; }
#endif

static int dev_mkdir(const char *name, mode_t mode)
{
	struct nameidata nd;
	struct dentry *dentry;
	int err;

	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
			      name, LOOKUP_PARENT, &nd);
	if (err)
		return err;

	dentry = lookup_create(&nd, 1);
	if (!IS_ERR(dentry)) {
		err = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
		if (!err)
			/* mark as kernel-created inode */
			dentry->d_inode->i_private = &dev_mnt;
		dput(dentry);
	} else {
		err = PTR_ERR(dentry);
	}

	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
	path_put(&nd.path);
	return err;
}

static int create_path(const char *nodepath)
{
	int err;

	mutex_lock(&dirlock);
	err = dev_mkdir(nodepath, 0755);
	if (err == -ENOENT) {
		char *path;
		char *s;

		/* parent directories do not exist, create them */
		path = kstrdup(nodepath, GFP_KERNEL);
		if (!path) {
			err = -ENOMEM;
			goto out;
		}
		s = path;
		for (;;) {
			s = strchr(s, '/');
			if (!s)
				break;
			s[0] = '\0';
			err = dev_mkdir(path, 0755);
			if (err && err != -EEXIST)
				break;
			s[0] = '/';
			s++;
		}
		kfree(path);
	}
out:
	mutex_unlock(&dirlock);
	return err;
}

int devtmpfs_create_node(struct device *dev)
{
	const char *tmp = NULL;
	const char *nodename;
	const struct cred *curr_cred;
	mode_t mode = 0;
	struct nameidata nd;
	struct dentry *dentry;
	int err;

	if (!dev_mnt)
		return 0;

	nodename = device_get_devnode(dev, &mode, &tmp);
	if (!nodename)
		return -ENOMEM;

	if (mode == 0)
		mode = 0600;
	if (is_blockdev(dev))
		mode |= S_IFBLK;
	else
		mode |= S_IFCHR;

	curr_cred = override_creds(&init_cred);

	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
			      nodename, LOOKUP_PARENT, &nd);
	if (err == -ENOENT) {
		create_path(nodename);
		err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
				      nodename, LOOKUP_PARENT, &nd);
	}
	if (err)
		goto out;

	dentry = lookup_create(&nd, 0);
	if (!IS_ERR(dentry)) {
		err = vfs_mknod(nd.path.dentry->d_inode,
				dentry, mode, dev->devt);
		if (!err) {
			struct iattr newattrs;

			/* fixup possibly umasked mode */
			newattrs.ia_mode = mode;
			newattrs.ia_valid = ATTR_MODE;
			mutex_lock(&dentry->d_inode->i_mutex);
			notify_change(dentry, &newattrs);
			mutex_unlock(&dentry->d_inode->i_mutex);

			/* mark as kernel-created inode */
			dentry->d_inode->i_private = &dev_mnt;
		}
		dput(dentry);
	} else {
		err = PTR_ERR(dentry);
	}

	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
	path_put(&nd.path);
out:
	kfree(tmp);
	revert_creds(curr_cred);
	return err;
}

static int dev_rmdir(const char *name)
{
	struct nameidata nd;
	struct dentry *dentry;
	int err;

	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
			      name, LOOKUP_PARENT, &nd);
	if (err)
		return err;

	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
	dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
	if (!IS_ERR(dentry)) {
		if (dentry->d_inode) {
			if (dentry->d_inode->i_private == &dev_mnt)
				err = vfs_rmdir(nd.path.dentry->d_inode,
						dentry);
			else
				err = -EPERM;
		} else {
			err = -ENOENT;
		}
		dput(dentry);
	} else {
		err = PTR_ERR(dentry);
	}

	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
	path_put(&nd.path);
	return err;
}

static int delete_path(const char *nodepath)
{
	const char *path;
	int err = 0;

	path = kstrdup(nodepath, GFP_KERNEL);
	if (!path)
		return -ENOMEM;

	mutex_lock(&dirlock);
	for (;;) {
		char *base;

		base = strrchr(path, '/');
		if (!base)
			break;
		base[0] = '\0';
		err = dev_rmdir(path);
		if (err)
			break;
	}
	mutex_unlock(&dirlock);

	kfree(path);
	return err;
}

static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
{
	/* did we create it */
	if (inode->i_private != &dev_mnt)
		return 0;

	/* does the dev_t match */
	if (is_blockdev(dev)) {
		if (!S_ISBLK(stat->mode))
			return 0;
	} else {
		if (!S_ISCHR(stat->mode))
			return 0;
	}
	if (stat->rdev != dev->devt)
		return 0;

	/* ours */
	return 1;
}

int devtmpfs_delete_node(struct device *dev)
{
	const char *tmp = NULL;
	const char *nodename;
	const struct cred *curr_cred;
	struct nameidata nd;
	struct dentry *dentry;
	struct kstat stat;
	int deleted = 1;
	int err;

	if (!dev_mnt)
		return 0;

	nodename = device_get_devnode(dev, NULL, &tmp);
	if (!nodename)
		return -ENOMEM;

	curr_cred = override_creds(&init_cred);
	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
			      nodename, LOOKUP_PARENT, &nd);
	if (err)
		goto out;

	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
	dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
	if (!IS_ERR(dentry)) {
		if (dentry->d_inode) {
			err = vfs_getattr(nd.path.mnt, dentry, &stat);
			if (!err && dev_mynode(dev, dentry->d_inode, &stat)) {
				struct iattr newattrs;
				/*
				 * before unlinking this node, reset permissions
				 * of possible references like hardlinks
				 */
				newattrs.ia_uid = 0;
				newattrs.ia_gid = 0;
				newattrs.ia_mode = stat.mode & ~0777;
				newattrs.ia_valid =
					ATTR_UID|ATTR_GID|ATTR_MODE;
				mutex_lock(&dentry->d_inode->i_mutex);
				notify_change(dentry, &newattrs);
				mutex_unlock(&dentry->d_inode->i_mutex);
				err = vfs_unlink(nd.path.dentry->d_inode,
						 dentry);
				if (!err || err == -ENOENT)
					deleted = 1;
			}
		} else {
			err = -ENOENT;
		}
		dput(dentry);
	} else {
		err = PTR_ERR(dentry);
	}
	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);

	path_put(&nd.path);
	if (deleted && strchr(nodename, '/'))
		delete_path(nodename);
out:
	kfree(tmp);
	revert_creds(curr_cred);
	return err;
}

/*
 * If configured, or requested by the commandline, devtmpfs will be
 * auto-mounted after the kernel mounted the root filesystem.
 */
int devtmpfs_mount(const char *mntdir)
{
	int err;

	if (!dev_mount)
		return 0;

	if (!dev_mnt)
		return 0;

	err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL);
	if (err)
		printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	else
		printk(KERN_INFO "devtmpfs: mounted\n");
	return err;
}

/*
 * Create devtmpfs instance, driver-core devices will add their device
 * nodes here.
 */
int __init devtmpfs_init(void)
{
	int err;
	struct vfsmount *mnt;
	char options[] = "mode=0755";

	err = register_filesystem(&dev_fs_type);
	if (err) {
		printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
		       "type %i\n", err);
		return err;
	}

	mnt = kern_mount_data(&dev_fs_type, options);
	if (IS_ERR(mnt)) {
		err = PTR_ERR(mnt);
		printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
		unregister_filesystem(&dev_fs_type);
		return err;
	}
	dev_mnt = mnt;

	printk(KERN_INFO "devtmpfs: initialized\n");
	return 0;
}
Commit	Line	Data
2b2af54a KS	1	/*
	2	* devtmpfs - kernel-maintained tmpfs-based /dev
	3	*
	4	* Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
	5	*
	6	* During bootup, before any driver core device is registered,
	7	* devtmpfs, a tmpfs-based filesystem is created. Every driver-core
	8	* device which requests a device node, will add a node in this
e454cea2 KS	9	* filesystem.
	10	* By default, all devices are named after the the name of the
	11	* device, owned by root and have a default mode of 0600. Subsystems
	12	* can overwrite the default setting if needed.
2b2af54a KS	13	*/
	14
	15	#include <linux/kernel.h>
	16	#include <linux/syscalls.h>
	17	#include <linux/mount.h>
	18	#include <linux/device.h>
	19	#include <linux/genhd.h>
	20	#include <linux/namei.h>
	21	#include <linux/fs.h>
	22	#include <linux/shmem_fs.h>
	23	#include <linux/cred.h>
e454cea2	24	#include <linux/sched.h>
2b2af54a	25	#include <linux/init_task.h>
5a0e3ad6	26	#include <linux/slab.h>
2b2af54a KS	27
	28	static struct vfsmount *dev_mnt;
	29
	30	#if defined CONFIG_DEVTMPFS_MOUNT
	31	static int dev_mount = 1;
	32	#else
	33	static int dev_mount;
	34	#endif
	35
f1f76f86	36	static DEFINE_MUTEX(dirlock);
ed413ae6	37
2b2af54a KS	38	static int __init mount_param(char *str)
	39	{
	40	dev_mount = simple_strtoul(str, NULL, 0);
	41	return 1;
	42	}
	43	__setup("devtmpfs.mount=", mount_param);
	44
	45	static int dev_get_sb(struct file_system_type *fs_type, int flags,
	46	const char dev_name, void data, struct vfsmount *mnt)
	47	{
	48	return get_sb_single(fs_type, flags, data, shmem_fill_super, mnt);
	49	}
	50
	51	static struct file_system_type dev_fs_type = {
	52	.name = "devtmpfs",
	53	.get_sb = dev_get_sb,
	54	.kill_sb = kill_litter_super,
	55	};
	56
	57	#ifdef CONFIG_BLOCK
	58	static inline int is_blockdev(struct device *dev)
	59	{
	60	return dev->class == &block_class;
	61	}
	62	#else
	63	static inline int is_blockdev(struct device *dev) { return 0; }
	64	#endif
	65
	66	static int dev_mkdir(const char *name, mode_t mode)
	67	{
	68	struct nameidata nd;
	69	struct dentry *dentry;
	70	int err;
	71
	72	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
	73	name, LOOKUP_PARENT, &nd);
	74	if (err)
	75	return err;
	76
	77	dentry = lookup_create(&nd, 1);
	78	if (!IS_ERR(dentry)) {
	79	err = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
015bf43b KS	80	if (!err)
	81	/* mark as kernel-created inode */
	82	dentry->d_inode->i_private = &dev_mnt;
2b2af54a KS	83	dput(dentry);
	84	} else {
	85	err = PTR_ERR(dentry);
	86	}
2b2af54a	87
015bf43b	88	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2b2af54a KS	89	path_put(&nd.path);
	90	return err;
	91	}
	92
	93	static int create_path(const char *nodepath)
	94	{
015bf43b	95	int err;
2b2af54a	96
f1f76f86	97	mutex_lock(&dirlock);
015bf43b KS	98	err = dev_mkdir(nodepath, 0755);
015bf43b KS	99	if (err == -ENOENT) {
ed413ae6	100	char *path;
2b2af54a KS	101	char *s;
	102
	103	/* parent directories do not exist, create them */
ed413ae6	104	path = kstrdup(nodepath, GFP_KERNEL);
80422738 KS	105	if (!path) {
	106	err = -ENOMEM;
	107	goto out;
	108	}
2b2af54a	109	s = path;
ed413ae6	110	for (;;) {
2b2af54a KS	111	s = strchr(s, '/');
	112	if (!s)
	113	break;
	114	s[0] = '\0';
	115	err = dev_mkdir(path, 0755);
	116	if (err && err != -EEXIST)
	117	break;
	118	s[0] = '/';
	119	s++;
	120	}
ed413ae6	121	kfree(path);
2b2af54a	122	}
80422738	123	out:
f1f76f86	124	mutex_unlock(&dirlock);
2b2af54a KS	125	return err;
	126	}
	127
	128	int devtmpfs_create_node(struct device *dev)
	129	{
	130	const char *tmp = NULL;
	131	const char *nodename;
	132	const struct cred *curr_cred;
e454cea2	133	mode_t mode = 0;
2b2af54a KS	134	struct nameidata nd;
	135	struct dentry *dentry;
	136	int err;
	137
	138	if (!dev_mnt)
	139	return 0;
	140
e454cea2	141	nodename = device_get_devnode(dev, &mode, &tmp);
2b2af54a KS	142	if (!nodename)
	143	return -ENOMEM;
	144
e454cea2 KS	145	if (mode == 0)
e454cea2 KS	146	mode = 0600;
2b2af54a	147	if (is_blockdev(dev))
e454cea2	148	mode \|= S_IFBLK;
2b2af54a	149	else
e454cea2	150	mode \|= S_IFCHR;
2b2af54a KS	151
2b2af54a KS	152	curr_cred = override_creds(&init_cred);
00926996	153
2b2af54a KS	154	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
	155	nodename, LOOKUP_PARENT, &nd);
	156	if (err == -ENOENT) {
2b2af54a KS	157	create_path(nodename);
	158	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
	159	nodename, LOOKUP_PARENT, &nd);
2b2af54a	160	}
00926996 KS	161	if (err)
00926996 KS	162	goto out;
2b2af54a KS	163
	164	dentry = lookup_create(&nd, 0);
	165	if (!IS_ERR(dentry)) {
	166	err = vfs_mknod(nd.path.dentry->d_inode,
	167	dentry, mode, dev->devt);
00926996 KS	168	if (!err) {
	169	struct iattr newattrs;
	170
	171	/* fixup possibly umasked mode */
	172	newattrs.ia_mode = mode;
	173	newattrs.ia_valid = ATTR_MODE;
	174	mutex_lock(&dentry->d_inode->i_mutex);
	175	notify_change(dentry, &newattrs);
	176	mutex_unlock(&dentry->d_inode->i_mutex);
	177
	178	/* mark as kernel-created inode */
2b2af54a	179	dentry->d_inode->i_private = &dev_mnt;
00926996	180	}
2b2af54a KS	181	dput(dentry);
	182	} else {
	183	err = PTR_ERR(dentry);
	184	}
2b2af54a	185
00926996	186	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2b2af54a KS	187	path_put(&nd.path);
	188	out:
	189	kfree(tmp);
	190	revert_creds(curr_cred);
	191	return err;
	192	}
	193
	194	static int dev_rmdir(const char *name)
	195	{
	196	struct nameidata nd;
	197	struct dentry *dentry;
	198	int err;
	199
	200	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
	201	name, LOOKUP_PARENT, &nd);
	202	if (err)
	203	return err;
	204
	205	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
	206	dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
	207	if (!IS_ERR(dentry)) {
015bf43b KS	208	if (dentry->d_inode) {
	209	if (dentry->d_inode->i_private == &dev_mnt)
	210	err = vfs_rmdir(nd.path.dentry->d_inode,
	211	dentry);
	212	else
	213	err = -EPERM;
	214	} else {
2b2af54a	215	err = -ENOENT;
015bf43b	216	}
2b2af54a KS	217	dput(dentry);
	218	} else {
	219	err = PTR_ERR(dentry);
	220	}
2b2af54a	221
015bf43b	222	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2b2af54a KS	223	path_put(&nd.path);
	224	return err;
	225	}
	226
	227	static int delete_path(const char *nodepath)
	228	{
	229	const char *path;
	230	int err = 0;
	231
	232	path = kstrdup(nodepath, GFP_KERNEL);
	233	if (!path)
	234	return -ENOMEM;
	235
f1f76f86	236	mutex_lock(&dirlock);
ed413ae6	237	for (;;) {
2b2af54a KS	238	char *base;
	239
	240	base = strrchr(path, '/');
	241	if (!base)
	242	break;
	243	base[0] = '\0';
	244	err = dev_rmdir(path);
	245	if (err)
	246	break;
	247	}
f1f76f86	248	mutex_unlock(&dirlock);
2b2af54a KS	249
	250	kfree(path);
	251	return err;
	252	}
	253
	254	static int dev_mynode(struct device dev, struct inode inode, struct kstat *stat)
	255	{
	256	/* did we create it */
	257	if (inode->i_private != &dev_mnt)
	258	return 0;
	259
	260	/* does the dev_t match */
	261	if (is_blockdev(dev)) {
	262	if (!S_ISBLK(stat->mode))
	263	return 0;
	264	} else {
	265	if (!S_ISCHR(stat->mode))
	266	return 0;
	267	}
	268	if (stat->rdev != dev->devt)
	269	return 0;
	270
	271	/* ours */
	272	return 1;
	273	}
	274
	275	int devtmpfs_delete_node(struct device *dev)
	276	{
	277	const char *tmp = NULL;
	278	const char *nodename;
	279	const struct cred *curr_cred;
	280	struct nameidata nd;
	281	struct dentry *dentry;
	282	struct kstat stat;
	283	int deleted = 1;
	284	int err;
	285
	286	if (!dev_mnt)
	287	return 0;
	288
e454cea2	289	nodename = device_get_devnode(dev, NULL, &tmp);
2b2af54a KS	290	if (!nodename)
	291	return -ENOMEM;
	292
	293	curr_cred = override_creds(&init_cred);
	294	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
	295	nodename, LOOKUP_PARENT, &nd);
	296	if (err)
	297	goto out;
	298
	299	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
	300	dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
	301	if (!IS_ERR(dentry)) {
	302	if (dentry->d_inode) {
	303	err = vfs_getattr(nd.path.mnt, dentry, &stat);
	304	if (!err && dev_mynode(dev, dentry->d_inode, &stat)) {
5e31d76f KS	305	struct iattr newattrs;
	306	/*
	307	* before unlinking this node, reset permissions
	308	* of possible references like hardlinks
	309	*/
	310	newattrs.ia_uid = 0;
	311	newattrs.ia_gid = 0;
	312	newattrs.ia_mode = stat.mode & ~0777;
	313	newattrs.ia_valid =
	314	ATTR_UID\|ATTR_GID\|ATTR_MODE;
	315	mutex_lock(&dentry->d_inode->i_mutex);
	316	notify_change(dentry, &newattrs);
	317	mutex_unlock(&dentry->d_inode->i_mutex);
2b2af54a KS	318	err = vfs_unlink(nd.path.dentry->d_inode,
	319	dentry);
	320	if (!err \|\| err == -ENOENT)
	321	deleted = 1;
	322	}
	323	} else {
	324	err = -ENOENT;
	325	}
	326	dput(dentry);
	327	} else {
	328	err = PTR_ERR(dentry);
	329	}
	330	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
	331
	332	path_put(&nd.path);
	333	if (deleted && strchr(nodename, '/'))
	334	delete_path(nodename);
	335	out:
	336	kfree(tmp);
	337	revert_creds(curr_cred);
	338	return err;
	339	}
	340
	341	/*
	342	* If configured, or requested by the commandline, devtmpfs will be
	343	* auto-mounted after the kernel mounted the root filesystem.
	344	*/
073120cc	345	int devtmpfs_mount(const char *mntdir)
2b2af54a	346	{
2b2af54a KS	347	int err;
	348
	349	if (!dev_mount)
	350	return 0;
	351
	352	if (!dev_mnt)
	353	return 0;
	354
073120cc	355	err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL);
2b2af54a KS	356	if (err)
	357	printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	358	else
	359	printk(KERN_INFO "devtmpfs: mounted\n");
2b2af54a KS	360	return err;
	361	}
	362
	363	/*
	364	* Create devtmpfs instance, driver-core devices will add their device
	365	* nodes here.
	366	*/
	367	int __init devtmpfs_init(void)
	368	{
	369	int err;
	370	struct vfsmount *mnt;
f776c5ec	371	char options[] = "mode=0755";
2b2af54a KS	372
	373	err = register_filesystem(&dev_fs_type);
	374	if (err) {
	375	printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
	376	"type %i\n", err);
	377	return err;
	378	}
	379
f776c5ec	380	mnt = kern_mount_data(&dev_fs_type, options);
2b2af54a KS	381	if (IS_ERR(mnt)) {
	382	err = PTR_ERR(mnt);
	383	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
	384	unregister_filesystem(&dev_fs_type);
	385	return err;
	386	}
	387	dev_mnt = mnt;
	388
	389	printk(KERN_INFO "devtmpfs: initialized\n");
	390	return 0;
	391	}