acl.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2007 Red Hat.  All rights reserved.
  4 */
  5
  6#include <linux/fs.h>
  7#include <linux/string.h>
  8#include <linux/xattr.h>
  9#include <linux/posix_acl_xattr.h>
 10#include <linux/posix_acl.h>
 11#include <linux/sched.h>
 12#include <linux/sched/mm.h>
 13#include <linux/slab.h>
 14#include "ctree.h"
 15#include "xattr.h"
 16#include "acl.h"
 17#include "misc.h"
 18
 19struct posix_acl *btrfs_get_acl(struct inode *inode, int type, bool rcu)
 20{
 21	int size;
 22	const char *name;
 23	char AUTO_KFREE(value);
 24	struct posix_acl *acl;
 25
 26	if (rcu)
 27		return ERR_PTR(-ECHILD);
 28
 29	switch (type) {
 30	case ACL_TYPE_ACCESS:
 31		name = XATTR_NAME_POSIX_ACL_ACCESS;
 32		break;
 33	case ACL_TYPE_DEFAULT:
 34		name = XATTR_NAME_POSIX_ACL_DEFAULT;
 35		break;
 36	default:
 37		return ERR_PTR(-EINVAL);
 38	}
 39
 40	size = btrfs_getxattr(inode, name, NULL, 0);
 41	if (size > 0) {
 42		value = kzalloc(size, GFP_KERNEL);
 43		if (!value)
 44			return ERR_PTR(-ENOMEM);
 45		size = btrfs_getxattr(inode, name, value, size);
 46	}
 47	if (size > 0)
 48		acl = posix_acl_from_xattr(&init_user_ns, value, size);
 49	else if (size == -ENODATA || size == 0)
 50		acl = NULL;
 51	else
 52		acl = ERR_PTR(size);
 53
 54	return acl;
 55}
 56
 57int __btrfs_set_acl(struct btrfs_trans_handle *trans, struct inode *inode,
 58		    struct posix_acl *acl, int type)
 59{
 60	int ret, size = 0;
 61	const char *name;
 62	char AUTO_KFREE(value);
 63
 64	switch (type) {
 65	case ACL_TYPE_ACCESS:
 66		name = XATTR_NAME_POSIX_ACL_ACCESS;
 67		break;
 68	case ACL_TYPE_DEFAULT:
 69		if (!S_ISDIR(inode->i_mode))
 70			return acl ? -EINVAL : 0;
 71		name = XATTR_NAME_POSIX_ACL_DEFAULT;
 72		break;
 73	default:
 74		return -EINVAL;
 75	}
 76
 77	if (acl) {
 78		unsigned int nofs_flag;
 79
 80		size = posix_acl_xattr_size(acl->a_count);
 81		/*
 82		 * We're holding a transaction handle, so use a NOFS memory
 83		 * allocation context to avoid deadlock if reclaim happens.
 84		 */
 85		nofs_flag = memalloc_nofs_save();
 86		value = kmalloc(size, GFP_KERNEL);
 87		memalloc_nofs_restore(nofs_flag);
 88		if (!value)
 89			return -ENOMEM;
 90
 91		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 92		if (ret < 0)
 93			return ret;
 94	}
 95
 96	if (trans)
 97		ret = btrfs_setxattr(trans, inode, name, value, size, 0);
 98	else
 99		ret = btrfs_setxattr_trans(inode, name, value, size, 0);
100	if (ret < 0)
101		return ret;
102
103	set_cached_acl(inode, type, acl);
104	return 0;
105}
106
107int btrfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
108		  struct posix_acl *acl, int type)
109{
110	int ret;
111	struct inode *inode = d_inode(dentry);
112	umode_t old_mode = inode->i_mode;
113
114	if (type == ACL_TYPE_ACCESS && acl) {
115		ret = posix_acl_update_mode(idmap, inode,
116					    &inode->i_mode, &acl);
117		if (ret)
118			return ret;
119	}
120	ret = __btrfs_set_acl(NULL, inode, acl, type);
121	if (ret)
122		inode->i_mode = old_mode;
123	return ret;
124}