Root/fs/btrfs/acl.c

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
31#ifdef CONFIG_BTRFS_FS_POSIX_ACL
32
33static struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
34{
35    int size;
36    const char *name;
37    char *value = NULL;
38    struct posix_acl *acl;
39
40    acl = get_cached_acl(inode, type);
41    if (acl != ACL_NOT_CACHED)
42        return acl;
43
44    switch (type) {
45    case ACL_TYPE_ACCESS:
46        name = POSIX_ACL_XATTR_ACCESS;
47        break;
48    case ACL_TYPE_DEFAULT:
49        name = POSIX_ACL_XATTR_DEFAULT;
50        break;
51    default:
52        BUG();
53    }
54
55    size = __btrfs_getxattr(inode, name, "", 0);
56    if (size > 0) {
57        value = kzalloc(size, GFP_NOFS);
58        if (!value)
59            return ERR_PTR(-ENOMEM);
60        size = __btrfs_getxattr(inode, name, value, size);
61        if (size > 0) {
62            acl = posix_acl_from_xattr(value, size);
63            set_cached_acl(inode, type, acl);
64        }
65        kfree(value);
66    } else if (size == -ENOENT || size == -ENODATA || size == 0) {
67        /* FIXME, who returns -ENOENT? I think nobody */
68        acl = NULL;
69        set_cached_acl(inode, type, acl);
70    } else {
71        acl = ERR_PTR(-EIO);
72    }
73
74    return acl;
75}
76
77static int btrfs_xattr_acl_get(struct dentry *dentry, const char *name,
78        void *value, size_t size, int type)
79{
80    struct posix_acl *acl;
81    int ret = 0;
82
83    acl = btrfs_get_acl(dentry->d_inode, type);
84
85    if (IS_ERR(acl))
86        return PTR_ERR(acl);
87    if (acl == NULL)
88        return -ENODATA;
89    ret = posix_acl_to_xattr(acl, value, size);
90    posix_acl_release(acl);
91
92    return ret;
93}
94
95/*
96 * Needs to be called with fs_mutex held
97 */
98static int btrfs_set_acl(struct btrfs_trans_handle *trans,
99             struct inode *inode, struct posix_acl *acl, int type)
100{
101    int ret, size = 0;
102    const char *name;
103    char *value = NULL;
104    mode_t mode;
105
106    if (acl) {
107        ret = posix_acl_valid(acl);
108        if (ret < 0)
109            return ret;
110        ret = 0;
111    }
112
113    switch (type) {
114    case ACL_TYPE_ACCESS:
115        mode = inode->i_mode;
116        name = POSIX_ACL_XATTR_ACCESS;
117        if (acl) {
118            ret = posix_acl_equiv_mode(acl, &mode);
119            if (ret < 0)
120                return ret;
121            inode->i_mode = mode;
122        }
123        ret = 0;
124        break;
125    case ACL_TYPE_DEFAULT:
126        if (!S_ISDIR(inode->i_mode))
127            return acl ? -EINVAL : 0;
128        name = POSIX_ACL_XATTR_DEFAULT;
129        break;
130    default:
131        return -EINVAL;
132    }
133
134    if (acl) {
135        size = posix_acl_xattr_size(acl->a_count);
136        value = kmalloc(size, GFP_NOFS);
137        if (!value) {
138            ret = -ENOMEM;
139            goto out;
140        }
141
142        ret = posix_acl_to_xattr(acl, value, size);
143        if (ret < 0)
144            goto out;
145    }
146
147    ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
148out:
149    kfree(value);
150
151    if (!ret)
152        set_cached_acl(inode, type, acl);
153
154    return ret;
155}
156
157static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
158        const void *value, size_t size, int flags, int type)
159{
160    int ret;
161    struct posix_acl *acl = NULL;
162
163    if (value) {
164        acl = posix_acl_from_xattr(value, size);
165        if (acl == NULL) {
166            value = NULL;
167            size = 0;
168        } else if (IS_ERR(acl)) {
169            return PTR_ERR(acl);
170        }
171    }
172
173    ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
174
175    posix_acl_release(acl);
176
177    return ret;
178}
179
180int btrfs_check_acl(struct inode *inode, int mask)
181{
182    struct posix_acl *acl;
183    int error = -EAGAIN;
184
185    acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
186
187    if (IS_ERR(acl))
188        return PTR_ERR(acl);
189    if (acl) {
190        error = posix_acl_permission(inode, acl, mask);
191        posix_acl_release(acl);
192    }
193
194    return error;
195}
196
197/*
198 * btrfs_init_acl is already generally called under fs_mutex, so the locking
199 * stuff has been fixed to work with that. If the locking stuff changes, we
200 * need to re-evaluate the acl locking stuff.
201 */
202int btrfs_init_acl(struct btrfs_trans_handle *trans,
203           struct inode *inode, struct inode *dir)
204{
205    struct posix_acl *acl = NULL;
206    int ret = 0;
207
208    /* this happens with subvols */
209    if (!dir)
210        return 0;
211
212    if (!S_ISLNK(inode->i_mode)) {
213        if (IS_POSIXACL(dir)) {
214            acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
215            if (IS_ERR(acl))
216                return PTR_ERR(acl);
217        }
218
219        if (!acl)
220            inode->i_mode &= ~current_umask();
221    }
222
223    if (IS_POSIXACL(dir) && acl) {
224        struct posix_acl *clone;
225        mode_t mode;
226
227        if (S_ISDIR(inode->i_mode)) {
228            ret = btrfs_set_acl(trans, inode, acl,
229                        ACL_TYPE_DEFAULT);
230            if (ret)
231                goto failed;
232        }
233        clone = posix_acl_clone(acl, GFP_NOFS);
234        ret = -ENOMEM;
235        if (!clone)
236            goto failed;
237
238        mode = inode->i_mode;
239        ret = posix_acl_create_masq(clone, &mode);
240        if (ret >= 0) {
241            inode->i_mode = mode;
242            if (ret > 0) {
243                /* we need an acl */
244                ret = btrfs_set_acl(trans, inode, clone,
245                            ACL_TYPE_ACCESS);
246            }
247        }
248        posix_acl_release(clone);
249    }
250failed:
251    posix_acl_release(acl);
252
253    return ret;
254}
255
256int btrfs_acl_chmod(struct inode *inode)
257{
258    struct posix_acl *acl, *clone;
259    int ret = 0;
260
261    if (S_ISLNK(inode->i_mode))
262        return -EOPNOTSUPP;
263
264    if (!IS_POSIXACL(inode))
265        return 0;
266
267    acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
268    if (IS_ERR(acl) || !acl)
269        return PTR_ERR(acl);
270
271    clone = posix_acl_clone(acl, GFP_KERNEL);
272    posix_acl_release(acl);
273    if (!clone)
274        return -ENOMEM;
275
276    ret = posix_acl_chmod_masq(clone, inode->i_mode);
277    if (!ret)
278        ret = btrfs_set_acl(NULL, inode, clone, ACL_TYPE_ACCESS);
279
280    posix_acl_release(clone);
281
282    return ret;
283}
284
285struct xattr_handler btrfs_xattr_acl_default_handler = {
286    .prefix = POSIX_ACL_XATTR_DEFAULT,
287    .flags = ACL_TYPE_DEFAULT,
288    .get = btrfs_xattr_acl_get,
289    .set = btrfs_xattr_acl_set,
290};
291
292struct xattr_handler btrfs_xattr_acl_access_handler = {
293    .prefix = POSIX_ACL_XATTR_ACCESS,
294    .flags = ACL_TYPE_ACCESS,
295    .get = btrfs_xattr_acl_get,
296    .set = btrfs_xattr_acl_set,
297};
298
299#else /* CONFIG_BTRFS_FS_POSIX_ACL */
300
301int btrfs_acl_chmod(struct inode *inode)
302{
303    return 0;
304}
305
306int btrfs_init_acl(struct btrfs_trans_handle *trans,
307           struct inode *inode, struct inode *dir)
308{
309    return 0;
310}
311
312#endif /* CONFIG_BTRFS_FS_POSIX_ACL */
313

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