397 lines
8.2 KiB
C
397 lines
8.2 KiB
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/ramfs.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)
|
|
{
|
|
#ifdef CONFIG_TMPFS
|
|
return get_sb_single(fs_type, flags, data, shmem_fill_super, mnt);
|
|
#else
|
|
return get_sb_single(fs_type, flags, data, ramfs_fill_super, mnt);
|
|
#endif
|
|
}
|
|
|
|
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;
|
|
}
|