1/*
2 * Copyright (C) 2007 Red Hat.  All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include <linux/fs.h>
20#include <linux/string.h>
21#include <linux/xattr.h>
22#include <linux/posix_acl_xattr.h>
23#include <linux/posix_acl.h>
24#include <linux/sched.h>
25#include <linux/slab.h>
26
27#include "ctree.h"
28#include "btrfs_inode.h"
29#include "xattr.h"
30
31struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
32{
33	int size;
34	const char *name;
35	char *value = NULL;
36	struct posix_acl *acl;
37
38	switch (type) {
39	case ACL_TYPE_ACCESS:
40		name = POSIX_ACL_XATTR_ACCESS;
41		break;
42	case ACL_TYPE_DEFAULT:
43		name = POSIX_ACL_XATTR_DEFAULT;
44		break;
45	default:
46		BUG();
47	}
48
49	size = __btrfs_getxattr(inode, name, "", 0);
50	if (size > 0) {
51		value = kzalloc(size, GFP_NOFS);
52		if (!value)
53			return ERR_PTR(-ENOMEM);
54		size = __btrfs_getxattr(inode, name, value, size);
55	}
56	if (size > 0) {
57		acl = posix_acl_from_xattr(&init_user_ns, value, size);
58	} else if (size == -ENOENT || size == -ENODATA || size == 0) {
59		/* FIXME, who returns -ENOENT?  I think nobody */
60		acl = NULL;
61	} else {
62		acl = ERR_PTR(-EIO);
63	}
64	kfree(value);
65
66	if (!IS_ERR(acl))
67		set_cached_acl(inode, type, acl);
68
69	return acl;
70}
71
72/*
73 * Needs to be called with fs_mutex held
74 */
75static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
76			 struct inode *inode, struct posix_acl *acl, int type)
77{
78	int ret, size = 0;
79	const char *name;
80	char *value = NULL;
81
82	switch (type) {
83	case ACL_TYPE_ACCESS:
84		name = POSIX_ACL_XATTR_ACCESS;
85		if (acl) {
86			ret = posix_acl_equiv_mode(acl, &inode->i_mode);
87			if (ret < 0)
88				return ret;
89			if (ret == 0)
90				acl = NULL;
91		}
92		ret = 0;
93		break;
94	case ACL_TYPE_DEFAULT:
95		if (!S_ISDIR(inode->i_mode))
96			return acl ? -EINVAL : 0;
97		name = POSIX_ACL_XATTR_DEFAULT;
98		break;
99	default:
100		return -EINVAL;
101	}
102
103	if (acl) {
104		size = posix_acl_xattr_size(acl->a_count);
105		value = kmalloc(size, GFP_NOFS);
106		if (!value) {
107			ret = -ENOMEM;
108			goto out;
109		}
110
111		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
112		if (ret < 0)
113			goto out;
114	}
115
116	ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
117out:
118	kfree(value);
119
120	if (!ret)
121		set_cached_acl(inode, type, acl);
122
123	return ret;
124}
125
126int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
127{
128	return __btrfs_set_acl(NULL, inode, acl, type);
129}
130
131/*
132 * btrfs_init_acl is already generally called under fs_mutex, so the locking
133 * stuff has been fixed to work with that.  If the locking stuff changes, we
134 * need to re-evaluate the acl locking stuff.
135 */
136int btrfs_init_acl(struct btrfs_trans_handle *trans,
137		   struct inode *inode, struct inode *dir)
138{
139	struct posix_acl *default_acl, *acl;
140	int ret = 0;
141
142	/* this happens with subvols */
143	if (!dir)
144		return 0;
145
146	ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
147	if (ret)
148		return ret;
149
150	if (default_acl) {
151		ret = __btrfs_set_acl(trans, inode, default_acl,
152				      ACL_TYPE_DEFAULT);
153		posix_acl_release(default_acl);
154	}
155
156	if (acl) {
157		if (!ret)
158			ret = __btrfs_set_acl(trans, inode, acl,
159					      ACL_TYPE_ACCESS);
160		posix_acl_release(acl);
161	}
162
163	if (!default_acl && !acl)
164		cache_no_acl(inode);
165	return ret;
166}
167