static int fuse_getattr(struct vfsmount *mnt, struct dentry *entry,
struct kstat *stat)
{
struct inode *inode = entry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
if (!fuse_allow_current_process(fc))
return -EACCES;
return fuse_update_attributes(inode, stat, NULL, NULL);
}
/*
* Check permission. The two basic access models of FUSE are:
*
* 1) Local access checking ('default_permissions' mount option) based
* on file mode. This is the plain old disk filesystem permission
* modell.
*
* 2) "Remote" access checking, where server is responsible for
* checking permission in each inode operation. An exception to this
* is if ->permission() was invoked from sys_access() in which case an
* access request is sent. Execute permission is still checked
* locally based on file mode.
*/
static int fuse_permission(struct inode *inode, int mask, unsigned int flags)
{
struct fuse_conn *fc = get_fuse_conn(inode);
bool refreshed = false;
int err = 0;
if (flags & IPERM_FLAG_RCU)
return -ECHILD;
if (!fuse_allow_task(fc, current))
return -EACCES;
/*
* If attributes are needed, refresh them before proceeding
*/
if ((fc->flags & FUSE_DEFAULT_PERMISSIONS) ||
((mask & MAY_EXEC) && S_ISREG(inode->i_mode))) {
err = fuse_update_attributes(inode, NULL, NULL, &refreshed);
if (err)
return err;
}
if (fc->flags & FUSE_DEFAULT_PERMISSIONS) {
err = generic_permission(inode, mask, flags, NULL);
/* If permission is denied, try to refresh file
attributes. This is also needed, because the root
node will at first have no permissions */
if (err == -EACCES && !refreshed) {
err = fuse_do_getattr(inode, NULL, NULL);
if (!err)
err = generic_permission(inode, mask,
flags, NULL);
}
/* Note: the opposite of the above test does not
exist. So if permissions are revoked this won't be
noticed immediately, only after the attribute
timeout has expired */
} else if (mask & (MAY_ACCESS | MAY_CHDIR)) {
err = fuse_access(inode, mask);
} else if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
if (!(inode->i_mode & S_IXUGO)) {
if (refreshed)
return -EACCES;
err = fuse_do_getattr(inode, NULL, NULL);
if (!err && !(inode->i_mode & S_IXUGO))
return -EACCES;
}
}
return err;
}