// 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_pivot_root(const char *new_root, const char *put_old)
{
        struct path new_path __free(path_put) = {};
        struct path old_path __free(path_put) = {};
        int ret;

        ret = kern_path(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &new_path);
        if (ret)
                return ret;

        ret = kern_path(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_path);
        if (ret)
                return ret;

        return path_pivot_root(&new_path, &old_path);
}

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 = path_permission(&path, 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 = path_permission(&path, 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 = path_permission(&path, 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)
{
        CLASS(filename_kernel, name)(filename);
        return filename_mknodat(AT_FDCWD, name, mode, dev);
}

int __init init_link(const char *oldname, const char *newname)
{
        CLASS(filename_kernel, old)(oldname);
        CLASS(filename_kernel, new)(newname);
        return filename_linkat(AT_FDCWD, old, AT_FDCWD, new, 0);
}

int __init init_symlink(const char *oldname, const char *newname)
{
        CLASS(filename_kernel, old)(oldname);
        CLASS(filename_kernel, new)(newname);
        return filename_symlinkat(old, AT_FDCWD, new);
}

int __init init_unlink(const char *pathname)
{
        CLASS(filename_kernel, name)(pathname);
        return filename_unlinkat(AT_FDCWD, name);
}

int __init init_mkdir(const char *pathname, umode_t mode)
{
        CLASS(filename_kernel, name)(pathname);
        return filename_mkdirat(AT_FDCWD, name, mode);
}

int __init init_rmdir(const char *pathname)
{
        CLASS(filename_kernel, name)(pathname);
        return filename_rmdir(AT_FDCWD, name);
}

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;
}