path: root/fs/overlayfs/copy_up.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Copyright (C) 2011 Novell Inc.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/fileattr.h>
#include <linux/splice.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/sched/signal.h>
#include <linux/cred.h>
#include <linux/namei.h>
#include <linux/fdtable.h>
#include <linux/ratelimit.h>
#include <linux/exportfs.h>
#include "overlayfs.h"

#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)

static int ovl_ccup_set(const char *buf, const struct kernel_param *param)
{
	pr_warn("\"check_copy_up\" module option is obsolete\n");
	return 0;
}

static int ovl_ccup_get(char *buf, const struct kernel_param *param)
{
	return sprintf(buf, "N\n");
}

module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644);
MODULE_PARM_DESC(check_copy_up, "Obsolete; does nothing");

static bool ovl_must_copy_xattr(const char *name)
{
	return !strcmp(name, XATTR_POSIX_ACL_ACCESS) ||
	       !strcmp(name, XATTR_POSIX_ACL_DEFAULT) ||
	       !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
}

static int ovl_copy_acl(struct ovl_fs *ofs, const struct path *path,
			struct dentry *dentry, const char *acl_name)
{
	int err;
	struct posix_acl *clone, *real_acl = NULL;

	real_acl = ovl_get_acl_path(path, acl_name, false);
	if (!real_acl)
		return 0;

	if (IS_ERR(real_acl)) {
		err = PTR_ERR(real_acl);
		if (err == -ENODATA || err == -EOPNOTSUPP)
			return 0;
		return err;
	}

	clone = posix_acl_clone(real_acl, GFP_KERNEL);
	posix_acl_release(real_acl); /* release original acl */
	if (!clone)
		return -ENOMEM;

	err = ovl_do_set_acl(ofs, dentry, acl_name, clone);

	/* release cloned acl */
	posix_acl_release(clone);
	return err;
}

int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct dentry *new)
{
	struct dentry *old = oldpath->dentry;
	ssize_t list_size, size, value_size = 0;
	char *buf, *name, *value = NULL;
	int error = 0;
	size_t slen;

	if (!old->d_inode->i_op->listxattr || !new->d_inode->i_op->listxattr)
		return 0;

	list_size = vfs_listxattr(old, NULL, 0);
	if (list_size <= 0) {
		if (list_size == -EOPNOTSUPP)
			return 0;
		return list_size;
	}

	buf = kvzalloc(list_size, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	list_size = vfs_listxattr(old, buf, list_size);
	if (list_size <= 0) {
		error = list_size;
		goto out;
	}

	for (name = buf; list_size; name += slen) {
		slen = strnlen(name, list_size) + 1;

		/* underlying fs providing us with an broken xattr list? */
		if (WARN_ON(slen > list_size)) {
			error = -EIO;
			break;
		}
		list_size -= slen;

		if (ovl_is_private_xattr(sb, name))
			continue;

		error = security_inode_copy_up_xattr(name);
		if (error < 0 && error != -EOPNOTSUPP