1 files changed, 269 insertions, 0 deletions
diff --git a/fs/init.c b/fs/init.c
new file mode 100644
index 000000000000..5c36adaa9b44
--- /dev/null
+++ b/fs/init.c
@@ -0,0 +1,269 @@
+// 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 = 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)
+{
+	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(mnt_user_ns(path.mnt), 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;
+	struct user_namespace *mnt_userns;
+	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;
+	mnt_userns = mnt_user_ns(new_path.mnt);
+	error = may_linkat(mnt_userns, &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, mnt_userns, 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(mnt_user_ns(path.mnt), 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(mnt_user_ns(path.mnt), 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;
+}