path: root/fs/posix_acl.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>
 *
 * Fixes from William Schumacher incorporated on 15 March 2001.
 *    (Reported by Charles Bertsch, <CBertsch@microtest.com>).
 */

/*
 *  This file contains generic functions for manipulating
 *  POSIX 1003.1e draft standard 17 ACLs.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/atomic.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/xattr.h>
#include <linux/export.h>
#include <linux/user_namespace.h>
#include <linux/namei.h>
#include <linux/mnt_idmapping.h>
#include <linux/iversion.h>
#include <linux/security.h>
#include <linux/evm.h>
#include <linux/fsnotify.h>
#include <linux/filelock.h>

#include "internal.h"

static struct posix_acl **acl_by_type(struct inode *inode, int type)
{
	switch (type) {
	case ACL_TYPE_ACCESS:
		return &inode->i_acl;
	case ACL_TYPE_DEFAULT:
		return &inode->i_default_acl;
	default:
		BUG();
	}
}

struct posix_acl *get_cached_acl(struct inode *inode, int type)
{
	struct posix_acl **p = acl_by_type(inode, type);
	struct posix_acl *acl;

	for (;;) {
		rcu_read_lock();
		acl = rcu_dereference(*p);
		if (!acl || is_uncached_acl(acl) ||
		    refcount_inc_not_zero(&acl->a_refcount))
			break;
		rcu_read_unlock();
		cpu_relax();
	}
	rcu_read_unlock();
	return acl;
}
EXPORT_SYMBOL(get_cached_acl);

struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
{
	struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type));

	if (acl == ACL_DONT_CACHE) {
		struct posix_acl *ret;

		ret = inode->i_op->get_inode_acl(inode, type, LOOKUP_RCU);
		if (!IS_ERR(ret))
			acl = ret;
	}

	return acl;
}
EXPORT_SYMBOL(get_cached_acl_rcu);

void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
{
	struct posix_acl **p = acl_by_type(inode, type);
	struct posix_acl *old;

	old = xchg(p, posix_acl_dup(acl));
	if (!is_uncached_acl(old))
		posix_acl_release(old);
}
EXPORT_SYMBOL(set_cached_acl);

static void __forget_cached_acl(struct posix_acl **p)
{
	struct posix_acl *old;

	old = xchg(p, ACL_NOT_CACHED);
	if (!is_uncached_acl(old))
		posix_acl_release(old);
}

void forget_cached_acl(struct inode *inode, int type)
{
	__forget_cached_acl(acl_by_type(inode, type));
}
EXPORT_SYMBOL(forget_cached_acl);

void forget_all_cached_acls(struct inode *inode)
{
	__forget_cached_acl(&