// SPDX-License-Identifier: GPL-2.0
  /*
   * Routines that mimic syscalls, but don't use the user address space or file
   * descriptors.  Only for init/ and related early init code.
   */
  #include <linux/init.h>
  #include <linux/mount.h>
  #include <linux/namei.h>
  #include <linux/fs.h>

  #include <linux/fs_struct.h>

  #include <linux/file.h>

  #include <linux/init_syscalls.h>

  #include <linux/security.h>

  #include "internal.h"
  
  int __init init_mount(const char *dev_name, const char *dir_name,
  		const char *type_page, unsigned long flags, void *data_page)
  {
  	struct path path;
  	int ret;
  
  	ret = kern_path(dir_name, LOOKUP_FOLLOW, &path);
  	if (ret)
  		return ret;
  	ret = path_mount(dev_name, &path, type_page, flags, data_page);
  	path_put(&path);
  	return ret;
  }

  
  int __init init_umount(const char *name, int flags)
  {
  	int lookup_flags = LOOKUP_MOUNTPOINT;
  	struct path path;
  	int ret;
  
  	if (!(flags & UMOUNT_NOFOLLOW))
  		lookup_flags |= LOOKUP_FOLLOW;
  	ret = kern_path(name, lookup_flags, &path);
  	if (ret)
  		return ret;
  	return path_umount(&path, flags);
  }

  int __init init_chdir(const char *filename)
  {
  	struct path path;
  	int error;
  
  	error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
  	if (error)
  		return error;
  	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
  	if (!error)
  		set_fs_pwd(current->fs, &path);
  	path_put(&path);
  	return error;
  }

  int __init init_chroot(const char *filename)
  {
  	struct path path;
  	int error;
  
  	error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
  	if (error)
  		return error;
  	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
  	if (error)
  		goto dput_and_out;
  	error = -EPERM;
  	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
  		goto dput_and_out;
  	error = security_path_chroot(&path);
  	if (error)
  		goto dput_and_out;
  	set_fs_root(current->fs, &path);
  dput_and_out:
  	path_put(&path);
  	return error;
  }

  int __init init_chown(const char *filename, uid_t user, gid_t group, int flags)
  {
  	int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
  	struct path path;
  	int error;
  
  	error = kern_path(filename, lookup_flags, &path);
  	if (error)
  		return error;
  	error = mnt_want_write(path.mnt);
  	if (!error) {
  		error = chown_common(&path, user, group);
  		mnt_drop_write(path.mnt);
  	}
  	path_put(&path);
  	return error;
  }

  int __init init_chmod(const char *filename, umode_t mode)
  {
  	struct path path;
  	int error;
  
  	error = kern_path(filename, LOOKUP_FOLLOW, &path);
  	if (error)
  		return error;
  	error = chmod_common(&path, mode);
  	path_put(&path);
  	return error;
  }

  int __init init_eaccess(const char *filename)
  {
  	struct path path;
  	int error;
  
  	error = kern_path(filename, LOOKUP_FOLLOW, &path);
  	if (error)
  		return error;
  	error = inode_permission(d_inode(path.dentry), MAY_ACCESS);
  	path_put(&path);
  	return error;
  }

  int __init init_stat(const char *filename, struct kstat *stat, int flags)
  {
  	int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
  	struct path path;
  	int error;
  
  	error = kern_path(filename, lookup_flags, &path);
  	if (error)
  		return error;
  	error = vfs_getattr(&path, stat, STATX_BASIC_STATS,
  			    flags | AT_NO_AUTOMOUNT);
  	path_put(&path);
  	return error;
  }

  int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
  {
  	struct dentry *dentry;
  	struct path path;
  	int error;
  
  	if (S_ISFIFO(mode) || S_ISSOCK(mode))
  		dev = 0;
  	else if (!(S_ISBLK(mode) || S_ISCHR(mode)))
  		return -EINVAL;
  
  	dentry = kern_path_create(AT_FDCWD, filename, &path, 0);
  	if (IS_ERR(dentry))
  		return PTR_ERR(dentry);
  
  	if (!IS_POSIXACL(path.dentry->d_inode))
  		mode &= ~current_umask();
  	error = security_path_mknod(&path, dentry, mode, dev);
  	if (!error)
  		error = vfs_mknod(path.dentry->d_inode, dentry, mode,
  				  new_decode_dev(dev));
  	done_path_create(&path, dentry);
  	return error;
  }

  int __init init_link(const char *oldname, const char *newname)
  {
  	struct dentry *new_dentry;
  	struct path old_path, new_path;
  	int error;
  
  	error = kern_path(oldname, 0, &old_path);
  	if (error)
  		return error;
  
  	new_dentry = kern_path_create(AT_FDCWD, newname, &new_path, 0);
  	error = PTR_ERR(new_dentry);
  	if (IS_ERR(new_dentry))
  		goto out;
  
  	error = -EXDEV;
  	if (old_path.mnt != new_path.mnt)
  		goto out_dput;
  	error = may_linkat(&old_path);
  	if (unlikely(error))
  		goto out_dput;
  	error = security_path_link(old_path.dentry, &new_path, new_dentry);
  	if (error)
  		goto out_dput;
  	error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry,
  			 NULL);
  out_dput:
  	done_path_create(&new_path, new_dentry);
  out:
  	path_put(&old_path);
  	return error;
  }

  int __init init_symlink(const char *oldname, const char *newname)
  {
  	struct dentry *dentry;
  	struct path path;
  	int error;
  
  	dentry = kern_path_create(AT_FDCWD, newname, &path, 0);
  	if (IS_ERR(dentry))
  		return PTR_ERR(dentry);
  	error = security_path_symlink(&path, dentry, oldname);
  	if (!error)
  		error = vfs_symlink(path.dentry->d_inode, dentry, oldname);
  	done_path_create(&path, dentry);
  	return error;
  }

  int __init init_unlink(const char *pathname)
  {
  	return do_unlinkat(AT_FDCWD, getname_kernel(pathname));
  }

  int __init init_mkdir(const char *pathname, umode_t mode)
  {
  	struct dentry *dentry;
  	struct path path;
  	int error;
  
  	dentry = kern_path_create(AT_FDCWD, pathname, &path, LOOKUP_DIRECTORY);
  	if (IS_ERR(dentry))
  		return PTR_ERR(dentry);
  	if (!IS_POSIXACL(path.dentry->d_inode))
  		mode &= ~current_umask();
  	error = security_path_mkdir(&path, dentry, mode);
  	if (!error)
  		error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
  	done_path_create(&path, dentry);
  	return error;
  }

  int __init init_rmdir(const char *pathname)
  {
  	return do_rmdir(AT_FDCWD, getname_kernel(pathname));
  }

  
  int __init init_utimes(char *filename, struct timespec64 *ts)
  {
  	struct path path;
  	int error;
  
  	error = kern_path(filename, 0, &path);
  	if (error)
  		return error;
  	error = vfs_utimes(&path, ts);
  	path_put(&path);
  	return error;
  }

  
  int __init init_dup(struct file *file)
  {
  	int fd;
  
  	fd = get_unused_fd_flags(0);
  	if (fd < 0)
  		return fd;
  	fd_install(fd, get_file(file));
  	return 0;
  }