forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
279 lines
6.8 KiB
279 lines
6.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
#include <linux/syscalls.h> |
|
#include <linux/slab.h> |
|
#include <linux/fs.h> |
|
#include <linux/file.h> |
|
#include <linux/mount.h> |
|
#include <linux/namei.h> |
|
#include <linux/exportfs.h> |
|
#include <linux/fs_struct.h> |
|
#include <linux/fsnotify.h> |
|
#include <linux/personality.h> |
|
#include <linux/uaccess.h> |
|
#include <linux/compat.h> |
|
#include "internal.h" |
|
#include "mount.h" |
|
|
|
static long do_sys_name_to_handle(struct path *path, |
|
struct file_handle __user *ufh, |
|
int __user *mnt_id) |
|
{ |
|
long retval; |
|
struct file_handle f_handle; |
|
int handle_dwords, handle_bytes; |
|
struct file_handle *handle = NULL; |
|
|
|
/* |
|
* We need to make sure whether the file system |
|
* support decoding of the file handle |
|
*/ |
|
if (!path->dentry->d_sb->s_export_op || |
|
!path->dentry->d_sb->s_export_op->fh_to_dentry) |
|
return -EOPNOTSUPP; |
|
|
|
if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) |
|
return -EFAULT; |
|
|
|
if (f_handle.handle_bytes > MAX_HANDLE_SZ) |
|
return -EINVAL; |
|
|
|
handle = kmalloc(sizeof(struct file_handle) + f_handle.handle_bytes, |
|
GFP_KERNEL); |
|
if (!handle) |
|
return -ENOMEM; |
|
|
|
/* convert handle size to multiple of sizeof(u32) */ |
|
handle_dwords = f_handle.handle_bytes >> 2; |
|
|
|
/* we ask for a non connected handle */ |
|
retval = exportfs_encode_fh(path->dentry, |
|
(struct fid *)handle->f_handle, |
|
&handle_dwords, 0); |
|
handle->handle_type = retval; |
|
/* convert handle size to bytes */ |
|
handle_bytes = handle_dwords * sizeof(u32); |
|
handle->handle_bytes = handle_bytes; |
|
if ((handle->handle_bytes > f_handle.handle_bytes) || |
|
(retval == FILEID_INVALID) || (retval == -ENOSPC)) { |
|
/* As per old exportfs_encode_fh documentation |
|
* we could return ENOSPC to indicate overflow |
|
* But file system returned 255 always. So handle |
|
* both the values |
|
*/ |
|
/* |
|
* set the handle size to zero so we copy only |
|
* non variable part of the file_handle |
|
*/ |
|
handle_bytes = 0; |
|
retval = -EOVERFLOW; |
|
} else |
|
retval = 0; |
|
/* copy the mount id */ |
|
if (put_user(real_mount(path->mnt)->mnt_id, mnt_id) || |
|
copy_to_user(ufh, handle, |
|
sizeof(struct file_handle) + handle_bytes)) |
|
retval = -EFAULT; |
|
kfree(handle); |
|
return retval; |
|
} |
|
|
|
/** |
|
* sys_name_to_handle_at: convert name to handle |
|
* @dfd: directory relative to which name is interpreted if not absolute |
|
* @name: name that should be converted to handle. |
|
* @handle: resulting file handle |
|
* @mnt_id: mount id of the file system containing the file |
|
* @flag: flag value to indicate whether to follow symlink or not |
|
* |
|
* @handle->handle_size indicate the space available to store the |
|
* variable part of the file handle in bytes. If there is not |
|
* enough space, the field is updated to return the minimum |
|
* value required. |
|
*/ |
|
SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name, |
|
struct file_handle __user *, handle, int __user *, mnt_id, |
|
int, flag) |
|
{ |
|
struct path path; |
|
int lookup_flags; |
|
int err; |
|
|
|
if ((flag & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
|
return -EINVAL; |
|
|
|
lookup_flags = (flag & AT_SYMLINK_FOLLOW) ? LOOKUP_FOLLOW : 0; |
|
if (flag & AT_EMPTY_PATH) |
|
lookup_flags |= LOOKUP_EMPTY; |
|
err = user_path_at(dfd, name, lookup_flags, &path); |
|
if (!err) { |
|
err = do_sys_name_to_handle(&path, handle, mnt_id); |
|
path_put(&path); |
|
} |
|
return err; |
|
} |
|
|
|
static struct vfsmount *get_vfsmount_from_fd(int fd) |
|
{ |
|
struct vfsmount *mnt; |
|
|
|
if (fd == AT_FDCWD) { |
|
struct fs_struct *fs = current->fs; |
|
spin_lock(&fs->lock); |
|
mnt = mntget(fs->pwd.mnt); |
|
spin_unlock(&fs->lock); |
|
} else { |
|
struct fd f = fdget(fd); |
|
if (!f.file) |
|
return ERR_PTR(-EBADF); |
|
mnt = mntget(f.file->f_path.mnt); |
|
fdput(f); |
|
} |
|
return mnt; |
|
} |
|
|
|
static int vfs_dentry_acceptable(void *context, struct dentry *dentry) |
|
{ |
|
return 1; |
|
} |
|
|
|
static int do_handle_to_path(int mountdirfd, struct file_handle *handle, |
|
struct path *path) |
|
{ |
|
int retval = 0; |
|
int handle_dwords; |
|
|
|
path->mnt = get_vfsmount_from_fd(mountdirfd); |
|
if (IS_ERR(path->mnt)) { |
|
retval = PTR_ERR(path->mnt); |
|
goto out_err; |
|
} |
|
/* change the handle size to multiple of sizeof(u32) */ |
|
handle_dwords = handle->handle_bytes >> 2; |
|
path->dentry = exportfs_decode_fh(path->mnt, |
|
(struct fid *)handle->f_handle, |
|
handle_dwords, handle->handle_type, |
|
vfs_dentry_acceptable, NULL); |
|
if (IS_ERR(path->dentry)) { |
|
retval = PTR_ERR(path->dentry); |
|
goto out_mnt; |
|
} |
|
return 0; |
|
out_mnt: |
|
mntput(path->mnt); |
|
out_err: |
|
return retval; |
|
} |
|
|
|
static int handle_to_path(int mountdirfd, struct file_handle __user *ufh, |
|
struct path *path) |
|
{ |
|
int retval = 0; |
|
struct file_handle f_handle; |
|
struct file_handle *handle = NULL; |
|
|
|
/* |
|
* With handle we don't look at the execute bit on the |
|
* directory. Ideally we would like CAP_DAC_SEARCH. |
|
* But we don't have that |
|
*/ |
|
if (!capable(CAP_DAC_READ_SEARCH)) { |
|
retval = -EPERM; |
|
goto out_err; |
|
} |
|
if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) { |
|
retval = -EFAULT; |
|
goto out_err; |
|
} |
|
if ((f_handle.handle_bytes > MAX_HANDLE_SZ) || |
|
(f_handle.handle_bytes == 0)) { |
|
retval = -EINVAL; |
|
goto out_err; |
|
} |
|
handle = kmalloc(sizeof(struct file_handle) + f_handle.handle_bytes, |
|
GFP_KERNEL); |
|
if (!handle) { |
|
retval = -ENOMEM; |
|
goto out_err; |
|
} |
|
/* copy the full handle */ |
|
*handle = f_handle; |
|
if (copy_from_user(&handle->f_handle, |
|
&ufh->f_handle, |
|
f_handle.handle_bytes)) { |
|
retval = -EFAULT; |
|
goto out_handle; |
|
} |
|
|
|
retval = do_handle_to_path(mountdirfd, handle, path); |
|
|
|
out_handle: |
|
kfree(handle); |
|
out_err: |
|
return retval; |
|
} |
|
|
|
static long do_handle_open(int mountdirfd, struct file_handle __user *ufh, |
|
int open_flag) |
|
{ |
|
long retval = 0; |
|
struct path path; |
|
struct file *file; |
|
int fd; |
|
|
|
retval = handle_to_path(mountdirfd, ufh, &path); |
|
if (retval) |
|
return retval; |
|
|
|
fd = get_unused_fd_flags(open_flag); |
|
if (fd < 0) { |
|
path_put(&path); |
|
return fd; |
|
} |
|
file = file_open_root(&path, "", open_flag, 0); |
|
if (IS_ERR(file)) { |
|
put_unused_fd(fd); |
|
retval = PTR_ERR(file); |
|
} else { |
|
retval = fd; |
|
fsnotify_open(file); |
|
fd_install(fd, file); |
|
} |
|
path_put(&path); |
|
return retval; |
|
} |
|
|
|
/** |
|
* sys_open_by_handle_at: Open the file handle |
|
* @mountdirfd: directory file descriptor |
|
* @handle: file handle to be opened |
|
* @flags: open flags. |
|
* |
|
* @mountdirfd indicate the directory file descriptor |
|
* of the mount point. file handle is decoded relative |
|
* to the vfsmount pointed by the @mountdirfd. @flags |
|
* value is same as the open(2) flags. |
|
*/ |
|
SYSCALL_DEFINE3(open_by_handle_at, int, mountdirfd, |
|
struct file_handle __user *, handle, |
|
int, flags) |
|
{ |
|
long ret; |
|
|
|
if (force_o_largefile()) |
|
flags |= O_LARGEFILE; |
|
|
|
ret = do_handle_open(mountdirfd, handle, flags); |
|
return ret; |
|
} |
|
|
|
#ifdef CONFIG_COMPAT |
|
/* |
|
* Exactly like fs/open.c:sys_open_by_handle_at(), except that it |
|
* doesn't set the O_LARGEFILE flag. |
|
*/ |
|
COMPAT_SYSCALL_DEFINE3(open_by_handle_at, int, mountdirfd, |
|
struct file_handle __user *, handle, int, flags) |
|
{ |
|
return do_handle_open(mountdirfd, handle, flags); |
|
} |
|
#endif
|
|
|