[linux-block.git] / drivers / base / devtmpfs.c

// SPDX-License-Identifier: GPL-2.0
/*
 * 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 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/blkdev.h>
#include <linux/namei.h>
#include <linux/fs.h>
#include <linux/shmem_fs.h>
#include <linux/ramfs.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/init_syscalls.h>
#include <uapi/linux/mount.h>
#include "base.h"

#ifdef CONFIG_DEVTMPFS_SAFE
#define DEVTMPFS_MFLAGS       (MS_SILENT | MS_NOEXEC | MS_NOSUID)
#else
#define DEVTMPFS_MFLAGS       (MS_SILENT)
#endif

static struct task_struct *thread;

static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);

static DEFINE_SPINLOCK(req_lock);

static struct req {
	struct req *next;
	struct completion done;
	int err;
	const char *name;
	umode_t mode;	/* 0 => delete */
	kuid_t uid;
	kgid_t gid;
	struct device *dev;
} *requests;

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

static struct vfsmount *mnt;

static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
		      const char *dev_name, void *data)
{
	struct super_block *s = mnt->mnt_sb;
	int err;

	atomic_inc(&s->s_active);
	down_write(&s->s_umount);
	err = reconfigure_single(s, flags, data);
	if (err < 0) {
		deactivate_locked_super(s);
		return ERR_PTR(err);
	}
	return dget(s->s_root);
}

static struct file_system_type internal_fs_type = {
	.name = "devtmpfs",
#ifdef CONFIG_TMPFS
	.init_fs_context = shmem_init_fs_context,
#else
	.init_fs_context = ramfs_init_fs_context,
#endif
	.kill_sb = kill_litter_super,
};

static struct file_system_type dev_fs_type = {
	.name = "devtmpfs",
	.mount = public_dev_mount,
};

#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 devtmpfs_submit_req(struct req *req, const char *tmp)
{
	init_completion(&req->done);

	spin_lock(&req_lock);
	req->next = requests;
	requests = req;
	spin_unlock(&req_lock);

	wake_up_process(thread);
	wait_for_completion(&req->done);

	kfree(tmp);

	return req->err;
}

int devtmpfs_create_node(struct device *dev)
{
	const char *tmp = NULL;
	struct req req;

	if (!thread)
		return 0;

	req.mode = 0;
	req.uid = GLOBAL_ROOT_UID;
	req.gid = GLOBAL_ROOT_GID;
	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
	if (!req.name)
		return -ENOMEM;

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

	req.dev = dev;

	return devtmpfs_submit_req(&req, tmp);
}

int devtmpfs_delete_node(struct device *dev)
{
	const char *tmp = NULL;
	struct req req;

	if (!thread)
		return 0;

	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
	if (!req.name)
		return -ENOMEM;

	req.mode = 0;
	req.dev = dev;

	return devtmpfs_submit_req(&req, tmp);
}

static int dev_mkdir(const char *name, umode_t mode)
{
	struct dentry *dentry;
	struct path path;
	int err;

	dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	err = vfs_mkdir(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode);
	if (!err)
		/* mark as kernel-created inode */
		d_inode(dentry)->i_private = &thread;
	done_path_create(&path, dentry);
	return err;
}

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

	/* parent directories do not exist, create them */
	path = kstrdup(nodepath, GFP_KERNEL);
	if (!path)
		return -ENOMEM;

	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);
	return err;
}

static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
			 kgid_t gid, struct device *dev)
{
	struct dentry *dentry;
	struct path path;
	int err;

	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
	if (dentry == ERR_PTR(-ENOENT)) {
		create_path(nodename);
		dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
	}
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

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

		newattrs.ia_mode = mode;
		newattrs.ia_uid = uid;
		newattrs.ia_gid = gid;
		newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
		inode_lock(d_inode(dentry));
		notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
		inode_unlock(d_inode(dentry));

		/* mark as kernel-created inode */
		d_inode(dentry)->i_private = &thread;
	}
	done_path_create(&path, dentry);
	return err;
}

static int dev_rmdir(const char *name)
{
	struct path parent;
	struct dentry *dentry;
	int err;

	dentry = kern_path_locked(name, &parent);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);
	if (d_really_is_positive(dentry)) {
		if (d_inode(dentry)->i_private == &thread)
			err = vfs_rmdir(&nop_mnt_idmap, d_inode(parent.dentry),
					dentry);
		else
			err = -EPERM;
	} else {
		err = -ENOENT;
	}
	dput(dentry);
	inode_unlock(d_inode(parent.dentry));
	path_put(&parent);
	return err;
}

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

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

	for (;;) {
		char *base;

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

	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 != &thread)
		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;
}

static int handle_remove(const char *nodename, struct device *dev)
{
	struct path parent;
	struct dentry *dentry;
	int deleted = 0;
	int err;

	dentry = kern_path_locked(nodename, &parent);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	if (d_really_is_positive(dentry)) {
		struct kstat stat;
		struct path p = {.mnt = parent.mnt, .dentry = dentry};
		err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
				  AT_STATX_SYNC_AS_STAT);
		if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
			struct iattr newattrs;
			/*
			 * before unlinking this node, reset permissions
			 * of possible references like hardlinks
			 */
			newattrs.ia_uid = GLOBAL_ROOT_UID;
			newattrs.ia_gid = GLOBAL_ROOT_GID;
			newattrs.ia_mode = stat.mode & ~0777;
			newattrs.ia_valid =
				ATTR_UID|ATTR_GID|ATTR_MODE;
			inode_lock(d_inode(dentry));
			notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
			inode_unlock(d_inode(dentry));
			err = vfs_unlink(&nop_mnt_idmap, d_inode(parent.dentry),
					 dentry, NULL);
			if (!err || err == -ENOENT)
				deleted = 1;
		}
	} else {
		err = -ENOENT;
	}
	dput(dentry);
	inode_unlock(d_inode(parent.dentry));

	path_put(&parent);
	if (deleted && strchr(nodename, '/'))
		delete_path(nodename);
	return err;
}

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

	if (!mount_dev)
		return 0;

	if (!thread)
		return 0;

	err = init_mount("devtmpfs", "dev", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
	if (err)
		printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	else
		printk(KERN_INFO "devtmpfs: mounted\n");
	return err;
}

static __initdata DECLARE_COMPLETION(setup_done);

static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
		  struct device *dev)
{
	if (mode)
		return handle_create(name, mode, uid, gid, dev);
	else
		return handle_remove(name, dev);
}

static void __noreturn devtmpfs_work_loop(void)
{
	while (1) {
		spin_lock(&req_lock);
		while (requests) {
			struct req *req = requests;
			requests = NULL;
			spin_unlock(&req_lock);
			while (req) {
				struct req *next = req->next;
				req->err = handle(req->name, req->mode,
						  req->uid, req->gid, req->dev);
				complete(&req->done);
				req = next;
			}
			spin_lock(&req_lock);
		}
		__set_current_state(TASK_INTERRUPTIBLE);
		spin_unlock(&req_lock);
		schedule();
	}
}

static noinline int __init devtmpfs_setup(void *p)
{
	int err;

	err = ksys_unshare(CLONE_NEWNS);
	if (err)
		goto out;
	err = init_mount("devtmpfs", "/", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
	if (err)
		goto out;
	init_chdir("/.."); /* will traverse into overmounted root */
	init_chroot(".");
out:
	*(int *)p = err;
	return err;
}

/*
 * The __ref is because devtmpfs_setup needs to be __init for the routines it
 * calls.  That call is done while devtmpfs_init, which is marked __init,
 * synchronously waits for it to complete.
 */
static int __ref devtmpfsd(void *p)
{
	int err = devtmpfs_setup(p);

	complete(&setup_done);
	if (err)
		return err;
	devtmpfs_work_loop();
	return 0;
}

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

	mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
	if (IS_ERR(mnt)) {
		printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
				PTR_ERR(mnt));
		return PTR_ERR(mnt);
	}
	err = register_filesystem(&dev_fs_type);
	if (err) {
		printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
		       "type %i\n", err);
		return err;
	}

	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	if (!IS_ERR(thread)) {
		wait_for_completion(&setup_done);
	} else {
		err = PTR_ERR(thread);
		thread = NULL;
	}

	if (err) {
		printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
		unregister_filesystem(&dev_fs_type);
		thread = NULL;
		return err;
	}

	printk(KERN_INFO "devtmpfs: initialized\n");
	return 0;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
2b2af54a KS	2	/*
	3	* devtmpfs - kernel-maintained tmpfs-based /dev
	4	*
	5	* Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
	6	*
	7	* During bootup, before any driver core device is registered,
	8	* devtmpfs, a tmpfs-based filesystem is created. Every driver-core
	9	* device which requests a device node, will add a node in this
e454cea2	10	* filesystem.
02fbe5e6 PK	11	* By default, all devices are named after the name of the device,
	12	* owned by root and have a default mode of 0600. Subsystems can
	13	* overwrite the default setting if needed.
2b2af54a KS	14	*/
	15
	16	#include <linux/kernel.h>
	17	#include <linux/syscalls.h>
	18	#include <linux/mount.h>
	19	#include <linux/device.h>
322cbb50	20	#include <linux/blkdev.h>
2b2af54a KS	21	#include <linux/namei.h>
	22	#include <linux/fs.h>
	23	#include <linux/shmem_fs.h>
da5e4ef7	24	#include <linux/ramfs.h>
e454cea2	25	#include <linux/sched.h>
5a0e3ad6	26	#include <linux/slab.h>
2780f1ff	27	#include <linux/kthread.h>
c60166f0	28	#include <linux/init_syscalls.h>
e262e32d	29	#include <uapi/linux/mount.h>
c3a30420	30	#include "base.h"
2b2af54a	31
28f0c335 KC	32	#ifdef CONFIG_DEVTMPFS_SAFE
	33	#define DEVTMPFS_MFLAGS (MS_SILENT \| MS_NOEXEC \| MS_NOSUID)
	34	#else
	35	#define DEVTMPFS_MFLAGS (MS_SILENT)
	36	#endif
	37
2780f1ff	38	static struct task_struct *thread;
2b2af54a	39
fad1db8a	40	static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
2b2af54a	41
2780f1ff AV	42	static DEFINE_SPINLOCK(req_lock);
	43
	44	static struct req {
	45	struct req *next;
	46	struct completion done;
	47	int err;
	48	const char *name;
2c9ede55	49	umode_t mode; /* 0 => delete */
4e4098a3 GKH	50	kuid_t uid;
4e4098a3 GKH	51	kgid_t gid;
2780f1ff AV	52	struct device *dev;
2780f1ff AV	53	} *requests;
ed413ae6	54
2b2af54a KS	55	static int __init mount_param(char *str)
2b2af54a KS	56	{
fc14f2fe	57	mount_dev = simple_strtoul(str, NULL, 0);
2b2af54a KS	58	return 1;
	59	}
	60	__setup("devtmpfs.mount=", mount_param);
	61
d401727e AV	62	static struct vfsmount *mnt;
	63
	64	static struct dentry public_dev_mount(struct file_system_type fs_type, int flags,
	65	const char dev_name, void data)
	66	{
	67	struct super_block *s = mnt->mnt_sb;
a6097180 N	68	int err;
a6097180 N	69
d401727e AV	70	atomic_inc(&s->s_active);
d401727e AV	71	down_write(&s->s_umount);
a6097180 N	72	err = reconfigure_single(s, flags, data);
	73	if (err < 0) {
	74	deactivate_locked_super(s);
	75	return ERR_PTR(err);
	76	}
d401727e AV	77	return dget(s->s_root);
	78	}
	79
f3235626 DH	80	static struct file_system_type internal_fs_type = {
f3235626 DH	81	.name = "devtmpfs",
da5e4ef7	82	#ifdef CONFIG_TMPFS
f3235626	83	.init_fs_context = shmem_init_fs_context,
da5e4ef7	84	#else
f3235626	85	.init_fs_context = ramfs_init_fs_context,
da5e4ef7	86	#endif
2b2af54a KS	87	.kill_sb = kill_litter_super,
	88	};
	89
d401727e AV	90	static struct file_system_type dev_fs_type = {
	91	.name = "devtmpfs",
	92	.mount = public_dev_mount,
	93	};
	94
2b2af54a KS	95	#ifdef CONFIG_BLOCK
	96	static inline int is_blockdev(struct device *dev)
	97	{
	98	return dev->class == &block_class;
	99	}
	100	#else
	101	static inline int is_blockdev(struct device *dev) { return 0; }
	102	#endif
	103
72a9cc95 RV	104	static int devtmpfs_submit_req(struct req req, const char tmp)
	105	{
	106	init_completion(&req->done);
	107
	108	spin_lock(&req_lock);
	109	req->next = requests;
	110	requests = req;
	111	spin_unlock(&req_lock);
	112
	113	wake_up_process(thread);
	114	wait_for_completion(&req->done);
	115
	116	kfree(tmp);
	117
	118	return req->err;
	119	}
	120
2780f1ff AV	121	int devtmpfs_create_node(struct device *dev)
	122	{
	123	const char *tmp = NULL;
	124	struct req req;
	125
	126	if (!thread)
	127	return 0;
	128
	129	req.mode = 0;
4e4098a3 GKH	130	req.uid = GLOBAL_ROOT_UID;
4e4098a3 GKH	131	req.gid = GLOBAL_ROOT_GID;
3c2670e6	132	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
2780f1ff AV	133	if (!req.name)
	134	return -ENOMEM;
	135
	136	if (req.mode == 0)
	137	req.mode = 0600;
	138	if (is_blockdev(dev))
	139	req.mode \|= S_IFBLK;
	140	else
	141	req.mode \|= S_IFCHR;
	142
	143	req.dev = dev;
	144
72a9cc95	145	return devtmpfs_submit_req(&req, tmp);
2780f1ff AV	146	}
	147
	148	int devtmpfs_delete_node(struct device *dev)
	149	{
	150	const char *tmp = NULL;
	151	struct req req;
	152
	153	if (!thread)
	154	return 0;
	155
3c2670e6	156	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
2780f1ff AV	157	if (!req.name)
	158	return -ENOMEM;
	159
	160	req.mode = 0;
	161	req.dev = dev;
	162
72a9cc95	163	return devtmpfs_submit_req(&req, tmp);
2780f1ff AV	164	}
2780f1ff AV	165
fbd48a69	166	static int dev_mkdir(const char *name, umode_t mode)
2b2af54a	167	{
2b2af54a	168	struct dentry *dentry;
69753a0f	169	struct path path;
2b2af54a KS	170	int err;
2b2af54a KS	171
1ac12b4b	172	dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
69753a0f AV	173	if (IS_ERR(dentry))
	174	return PTR_ERR(dentry);
	175
abf08576	176	err = vfs_mkdir(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode);
69753a0f AV	177	if (!err)
69753a0f AV	178	/* mark as kernel-created inode */
75c3cfa8	179	d_inode(dentry)->i_private = &thread;
921a1650	180	done_path_create(&path, dentry);
2b2af54a KS	181	return err;
	182	}
	183
	184	static int create_path(const char *nodepath)
	185	{
5da4e689 AV	186	char *path;
5da4e689 AV	187	char *s;
9d108d25	188	int err = 0;
2b2af54a	189
5da4e689 AV	190	/* parent directories do not exist, create them */
	191	path = kstrdup(nodepath, GFP_KERNEL);
	192	if (!path)
	193	return -ENOMEM;
	194
	195	s = path;
	196	for (;;) {
	197	s = strchr(s, '/');
	198	if (!s)
	199	break;
	200	s[0] = '\0';
	201	err = dev_mkdir(path, 0755);
	202	if (err && err != -EEXIST)
	203	break;
	204	s[0] = '/';
	205	s++;
2b2af54a	206	}
5da4e689	207	kfree(path);
2b2af54a KS	208	return err;
	209	}
	210
4e4098a3 GKH	211	static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
4e4098a3 GKH	212	kgid_t gid, struct device *dev)
2b2af54a	213	{
2b2af54a	214	struct dentry *dentry;
69753a0f	215	struct path path;
2b2af54a KS	216	int err;
2b2af54a KS	217
69753a0f AV	218	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
69753a0f AV	219	if (dentry == ERR_PTR(-ENOENT)) {
2b2af54a	220	create_path(nodename);
69753a0f	221	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
2b2af54a	222	}
69753a0f AV	223	if (IS_ERR(dentry))
	224	return PTR_ERR(dentry);
	225
abf08576	226	err = vfs_mknod(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode,
6521f891	227	dev->devt);
69753a0f AV	228	if (!err) {
	229	struct iattr newattrs;
	230
69753a0f	231	newattrs.ia_mode = mode;
4e4098a3 GKH	232	newattrs.ia_uid = uid;
4e4098a3 GKH	233	newattrs.ia_gid = gid;
3c2670e6	234	newattrs.ia_valid = ATTR_MODE\|ATTR_UID\|ATTR_GID;
5955102c	235	inode_lock(d_inode(dentry));
abf08576	236	notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
5955102c	237	inode_unlock(d_inode(dentry));
69753a0f AV	238
69753a0f AV	239	/* mark as kernel-created inode */
75c3cfa8	240	d_inode(dentry)->i_private = &thread;
2b2af54a	241	}
921a1650	242	done_path_create(&path, dentry);
2b2af54a KS	243	return err;
	244	}
	245
	246	static int dev_rmdir(const char *name)
	247	{
79714f72	248	struct path parent;
2b2af54a KS	249	struct dentry *dentry;
	250	int err;
	251
79714f72 AV	252	dentry = kern_path_locked(name, &parent);
	253	if (IS_ERR(dentry))
	254	return PTR_ERR(dentry);
75c3cfa8 DH	255	if (d_really_is_positive(dentry)) {
75c3cfa8 DH	256	if (d_inode(dentry)->i_private == &thread)
abf08576	257	err = vfs_rmdir(&nop_mnt_idmap, d_inode(parent.dentry),
6521f891	258	dentry);
79714f72 AV	259	else
79714f72 AV	260	err = -EPERM;
2b2af54a	261	} else {
79714f72	262	err = -ENOENT;
2b2af54a	263	}
79714f72	264	dput(dentry);
5955102c	265	inode_unlock(d_inode(parent.dentry));
79714f72	266	path_put(&parent);
2b2af54a KS	267	return err;
	268	}
	269
	270	static int delete_path(const char *nodepath)
	271	{
be6b1dfe	272	char *path;
2b2af54a KS	273	int err = 0;
	274
	275	path = kstrdup(nodepath, GFP_KERNEL);
	276	if (!path)
	277	return -ENOMEM;
	278
ed413ae6	279	for (;;) {
2b2af54a KS	280	char *base;
	281
	282	base = strrchr(path, '/');
	283	if (!base)
	284	break;
	285	base[0] = '\0';
	286	err = dev_rmdir(path);
	287	if (err)
	288	break;
	289	}
	290
	291	kfree(path);
	292	return err;
	293	}
	294
	295	static int dev_mynode(struct device dev, struct inode inode, struct kstat *stat)
	296	{
	297	/* did we create it */
2780f1ff	298	if (inode->i_private != &thread)
2b2af54a KS	299	return 0;
	300
	301	/* does the dev_t match */
	302	if (is_blockdev(dev)) {
	303	if (!S_ISBLK(stat->mode))
	304	return 0;
	305	} else {
	306	if (!S_ISCHR(stat->mode))
	307	return 0;
	308	}
	309	if (stat->rdev != dev->devt)
	310	return 0;
	311
	312	/* ours */
	313	return 1;
	314	}
	315
2780f1ff	316	static int handle_remove(const char nodename, struct device dev)
2b2af54a	317	{
79714f72	318	struct path parent;
2b2af54a	319	struct dentry *dentry;
fbde7c61	320	int deleted = 0;
2b2af54a KS	321	int err;
2b2af54a KS	322
79714f72 AV	323	dentry = kern_path_locked(nodename, &parent);
	324	if (IS_ERR(dentry))
	325	return PTR_ERR(dentry);
	326
75c3cfa8	327	if (d_really_is_positive(dentry)) {
79714f72	328	struct kstat stat;
3dadecce	329	struct path p = {.mnt = parent.mnt, .dentry = dentry};
a528d35e DH	330	err = vfs_getattr(&p, &stat, STATX_TYPE \| STATX_MODE,
a528d35e DH	331	AT_STATX_SYNC_AS_STAT);
75c3cfa8	332	if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
79714f72 AV	333	struct iattr newattrs;
	334	/*
	335	* before unlinking this node, reset permissions
	336	* of possible references like hardlinks
	337	*/
91fa2cca EB	338	newattrs.ia_uid = GLOBAL_ROOT_UID;
91fa2cca EB	339	newattrs.ia_gid = GLOBAL_ROOT_GID;
79714f72 AV	340	newattrs.ia_mode = stat.mode & ~0777;
	341	newattrs.ia_valid =
	342	ATTR_UID\|ATTR_GID\|ATTR_MODE;
5955102c	343	inode_lock(d_inode(dentry));
abf08576	344	notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
5955102c	345	inode_unlock(d_inode(dentry));
abf08576	346	err = vfs_unlink(&nop_mnt_idmap, d_inode(parent.dentry),
6521f891	347	dentry, NULL);
79714f72 AV	348	if (!err \|\| err == -ENOENT)
79714f72 AV	349	deleted = 1;
2b2af54a	350	}
2b2af54a	351	} else {
79714f72	352	err = -ENOENT;
2b2af54a	353	}
79714f72	354	dput(dentry);
5955102c	355	inode_unlock(d_inode(parent.dentry));
2b2af54a	356
79714f72	357	path_put(&parent);
2b2af54a KS	358	if (deleted && strchr(nodename, '/'))
2b2af54a KS	359	delete_path(nodename);
2b2af54a KS	360	return err;
	361	}
	362
	363	/*
	364	* If configured, or requested by the commandline, devtmpfs will be
	365	* auto-mounted after the kernel mounted the root filesystem.
	366	*/
fad1db8a	367	int __init devtmpfs_mount(void)
2b2af54a	368	{
2b2af54a KS	369	int err;
2b2af54a KS	370
fc14f2fe	371	if (!mount_dev)
2b2af54a KS	372	return 0;
2b2af54a KS	373
2780f1ff	374	if (!thread)
2b2af54a KS	375	return 0;
2b2af54a KS	376
28f0c335	377	err = init_mount("devtmpfs", "dev", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
2b2af54a KS	378	if (err)
	379	printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	380	else
	381	printk(KERN_INFO "devtmpfs: mounted\n");
2b2af54a KS	382	return err;
	383	}
	384
01085e24	385	static __initdata DECLARE_COMPLETION(setup_done);
2780f1ff	386
4e4098a3	387	static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
3c2670e6	388	struct device *dev)
2780f1ff AV	389	{
2780f1ff AV	390	if (mode)
3c2670e6	391	return handle_create(name, mode, uid, gid, dev);
2780f1ff AV	392	else
	393	return handle_remove(name, dev);
	394	}
	395
bcbacc49 CH	396	static void __noreturn devtmpfs_work_loop(void)
	397	{
	398	while (1) {
	399	spin_lock(&req_lock);
	400	while (requests) {
	401	struct req *req = requests;
	402	requests = NULL;
	403	spin_unlock(&req_lock);
	404	while (req) {
	405	struct req *next = req->next;
	406	req->err = handle(req->name, req->mode,
	407	req->uid, req->gid, req->dev);
	408	complete(&req->done);
	409	req = next;
	410	}
	411	spin_lock(&req_lock);
	412	}
	413	__set_current_state(TASK_INTERRUPTIBLE);
	414	spin_unlock(&req_lock);
	415	schedule();
	416	}
	417	}
	418
01085e24	419	static noinline int __init devtmpfs_setup(void *p)
2780f1ff	420	{
c9d6b287 RV	421	int err;
	422
	423	err = ksys_unshare(CLONE_NEWNS);
	424	if (err)
2780f1ff	425	goto out;
28f0c335	426	err = init_mount("devtmpfs", "/", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
c9d6b287	427	if (err)
2780f1ff	428	goto out;
db63f1e3	429	init_chdir("/.."); /* will traverse into overmounted root */
4b7ca501	430	init_chroot(".");
0ff0e95e RV	431	out:
0ff0e95e RV	432	(int )p = err;
0ff0e95e RV	433	return err;
	434	}
	435
bcbacc49 CH	436	/*
	437	* The __ref is because devtmpfs_setup needs to be __init for the routines it
	438	* calls. That call is done while devtmpfs_init, which is marked __init,
	439	* synchronously waits for it to complete.
	440	*/
	441	static int __ref devtmpfsd(void *p)
0ff0e95e RV	442	{
	443	int err = devtmpfs_setup(p);
	444
38f087de	445	complete(&setup_done);
0ff0e95e RV	446	if (err)
0ff0e95e RV	447	return err;
bcbacc49	448	devtmpfs_work_loop();
2780f1ff	449	return 0;
2780f1ff AV	450	}
2780f1ff AV	451
2b2af54a KS	452	/*
	453	* Create devtmpfs instance, driver-core devices will add their device
	454	* nodes here.
	455	*/
	456	int __init devtmpfs_init(void)
	457	{
d401727e AV	458	char opts[] = "mode=0755";
	459	int err;
	460
	461	mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
	462	if (IS_ERR(mnt)) {
	463	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
	464	PTR_ERR(mnt));
	465	return PTR_ERR(mnt);
	466	}
	467	err = register_filesystem(&dev_fs_type);
2b2af54a KS	468	if (err) {
	469	printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
	470	"type %i\n", err);
	471	return err;
	472	}
	473
2780f1ff AV	474	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	475	if (!IS_ERR(thread)) {
	476	wait_for_completion(&setup_done);
	477	} else {
	478	err = PTR_ERR(thread);
	479	thread = NULL;
	480	}
	481
	482	if (err) {
2b2af54a KS	483	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
2b2af54a KS	484	unregister_filesystem(&dev_fs_type);
31c779f2	485	thread = NULL;
2b2af54a KS	486	return err;
2b2af54a KS	487	}
2b2af54a KS	488
	489	printk(KERN_INFO "devtmpfs: initialized\n");
	490	return 0;
	491	}