mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
![Greg Kroah-Hartman](/assets/img/avatar_default.png)
Now that devtmpfs is caring about uid/gid, we need to use the correct internal types so users who have USER_NS enabled will have things work properly for them. Thanks to Eric for pointing this out, and the patch review. Reported-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Ming Lei <ming.lei@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
443 lines
9 KiB
C
443 lines
9 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 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/sched.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/kthread.h>
|
|
#include "base.h"
|
|
|
|
static struct task_struct *thread;
|
|
|
|
#if defined CONFIG_DEVTMPFS_MOUNT
|
|
static int mount_dev = 1;
|
|
#else
|
|
static int mount_dev;
|
|
#endif
|
|
|
|
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 dentry *dev_mount(struct file_system_type *fs_type, int flags,
|
|
const char *dev_name, void *data)
|
|
{
|
|
#ifdef CONFIG_TMPFS
|
|
return mount_single(fs_type, flags, data, shmem_fill_super);
|
|
#else
|
|
return mount_single(fs_type, flags, data, ramfs_fill_super);
|
|
#endif
|
|
}
|
|
|
|
static struct file_system_type dev_fs_type = {
|
|
.name = "devtmpfs",
|
|
.mount = dev_mount,
|
|
.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
|
|
|
|
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;
|
|
|
|
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_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;
|
|
|
|
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;
|
|
}
|
|
|
|
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(path.dentry->d_inode, dentry, mode);
|
|
if (!err)
|
|
/* mark as kernel-created inode */
|
|
dentry->d_inode->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(path.dentry->d_inode, 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;
|
|
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 = &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 (dentry->d_inode) {
|
|
if (dentry->d_inode->i_private == &thread)
|
|
err = vfs_rmdir(parent.dentry->d_inode, dentry);
|
|
else
|
|
err = -EPERM;
|
|
} else {
|
|
err = -ENOENT;
|
|
}
|
|
dput(dentry);
|
|
mutex_unlock(&parent.dentry->d_inode->i_mutex);
|
|
path_put(&parent);
|
|
return err;
|
|
}
|
|
|
|
static int delete_path(const char *nodepath)
|
|
{
|
|
const 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 = 1;
|
|
int err;
|
|
|
|
dentry = kern_path_locked(nodename, &parent);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
|
|
if (dentry->d_inode) {
|
|
struct kstat stat;
|
|
struct path p = {.mnt = parent.mnt, .dentry = dentry};
|
|
err = vfs_getattr(&p, &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 = GLOBAL_ROOT_UID;
|
|
newattrs.ia_gid = GLOBAL_ROOT_GID;
|
|
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(parent.dentry->d_inode, dentry);
|
|
if (!err || err == -ENOENT)
|
|
deleted = 1;
|
|
}
|
|
} else {
|
|
err = -ENOENT;
|
|
}
|
|
dput(dentry);
|
|
mutex_unlock(&parent.dentry->d_inode->i_mutex);
|
|
|
|
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 devtmpfs_mount(const char *mntdir)
|
|
{
|
|
int err;
|
|
|
|
if (!mount_dev)
|
|
return 0;
|
|
|
|
if (!thread)
|
|
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;
|
|
}
|
|
|
|
static 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 int devtmpfsd(void *p)
|
|
{
|
|
char options[] = "mode=0755";
|
|
int *err = p;
|
|
*err = sys_unshare(CLONE_NEWNS);
|
|
if (*err)
|
|
goto out;
|
|
*err = sys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
|
|
if (*err)
|
|
goto out;
|
|
sys_chdir("/.."); /* will traverse into overmounted root */
|
|
sys_chroot(".");
|
|
complete(&setup_done);
|
|
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();
|
|
}
|
|
return 0;
|
|
out:
|
|
complete(&setup_done);
|
|
return *err;
|
|
}
|
|
|
|
/*
|
|
* Create devtmpfs instance, driver-core devices will add their device
|
|
* nodes here.
|
|
*/
|
|
int __init devtmpfs_init(void)
|
|
{
|
|
int 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);
|
|
return err;
|
|
}
|
|
|
|
printk(KERN_INFO "devtmpfs: initialized\n");
|
|
return 0;
|
|
}
|