Root/fs/ext3/acl.c

1/*
2 * linux/fs/ext3/acl.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5 */
6
7#include <linux/init.h>
8#include <linux/sched.h>
9#include <linux/slab.h>
10#include <linux/capability.h>
11#include <linux/fs.h>
12#include <linux/ext3_jbd.h>
13#include <linux/ext3_fs.h>
14#include "xattr.h"
15#include "acl.h"
16
17/*
18 * Convert from filesystem to in-memory representation.
19 */
20static struct posix_acl *
21ext3_acl_from_disk(const void *value, size_t size)
22{
23    const char *end = (char *)value + size;
24    int n, count;
25    struct posix_acl *acl;
26
27    if (!value)
28        return NULL;
29    if (size < sizeof(ext3_acl_header))
30         return ERR_PTR(-EINVAL);
31    if (((ext3_acl_header *)value)->a_version !=
32        cpu_to_le32(EXT3_ACL_VERSION))
33        return ERR_PTR(-EINVAL);
34    value = (char *)value + sizeof(ext3_acl_header);
35    count = ext3_acl_count(size);
36    if (count < 0)
37        return ERR_PTR(-EINVAL);
38    if (count == 0)
39        return NULL;
40    acl = posix_acl_alloc(count, GFP_NOFS);
41    if (!acl)
42        return ERR_PTR(-ENOMEM);
43    for (n=0; n < count; n++) {
44        ext3_acl_entry *entry =
45            (ext3_acl_entry *)value;
46        if ((char *)value + sizeof(ext3_acl_entry_short) > end)
47            goto fail;
48        acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
49        acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
50        switch(acl->a_entries[n].e_tag) {
51            case ACL_USER_OBJ:
52            case ACL_GROUP_OBJ:
53            case ACL_MASK:
54            case ACL_OTHER:
55                value = (char *)value +
56                    sizeof(ext3_acl_entry_short);
57                acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
58                break;
59
60            case ACL_USER:
61            case ACL_GROUP:
62                value = (char *)value + sizeof(ext3_acl_entry);
63                if ((char *)value > end)
64                    goto fail;
65                acl->a_entries[n].e_id =
66                    le32_to_cpu(entry->e_id);
67                break;
68
69            default:
70                goto fail;
71        }
72    }
73    if (value != end)
74        goto fail;
75    return acl;
76
77fail:
78    posix_acl_release(acl);
79    return ERR_PTR(-EINVAL);
80}
81
82/*
83 * Convert from in-memory to filesystem representation.
84 */
85static void *
86ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
87{
88    ext3_acl_header *ext_acl;
89    char *e;
90    size_t n;
91
92    *size = ext3_acl_size(acl->a_count);
93    ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
94            sizeof(ext3_acl_entry), GFP_NOFS);
95    if (!ext_acl)
96        return ERR_PTR(-ENOMEM);
97    ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
98    e = (char *)ext_acl + sizeof(ext3_acl_header);
99    for (n=0; n < acl->a_count; n++) {
100        ext3_acl_entry *entry = (ext3_acl_entry *)e;
101        entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
102        entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
103        switch(acl->a_entries[n].e_tag) {
104            case ACL_USER:
105            case ACL_GROUP:
106                entry->e_id =
107                    cpu_to_le32(acl->a_entries[n].e_id);
108                e += sizeof(ext3_acl_entry);
109                break;
110
111            case ACL_USER_OBJ:
112            case ACL_GROUP_OBJ:
113            case ACL_MASK:
114            case ACL_OTHER:
115                e += sizeof(ext3_acl_entry_short);
116                break;
117
118            default:
119                goto fail;
120        }
121    }
122    return (char *)ext_acl;
123
124fail:
125    kfree(ext_acl);
126    return ERR_PTR(-EINVAL);
127}
128
129/*
130 * Inode operation get_posix_acl().
131 *
132 * inode->i_mutex: don't care
133 */
134static struct posix_acl *
135ext3_get_acl(struct inode *inode, int type)
136{
137    int name_index;
138    char *value = NULL;
139    struct posix_acl *acl;
140    int retval;
141
142    if (!test_opt(inode->i_sb, POSIX_ACL))
143        return NULL;
144
145    acl = get_cached_acl(inode, type);
146    if (acl != ACL_NOT_CACHED)
147        return acl;
148
149    switch (type) {
150    case ACL_TYPE_ACCESS:
151        name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
152        break;
153    case ACL_TYPE_DEFAULT:
154        name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
155        break;
156    default:
157        BUG();
158    }
159
160    retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
161    if (retval > 0) {
162        value = kmalloc(retval, GFP_NOFS);
163        if (!value)
164            return ERR_PTR(-ENOMEM);
165        retval = ext3_xattr_get(inode, name_index, "", value, retval);
166    }
167    if (retval > 0)
168        acl = ext3_acl_from_disk(value, retval);
169    else if (retval == -ENODATA || retval == -ENOSYS)
170        acl = NULL;
171    else
172        acl = ERR_PTR(retval);
173    kfree(value);
174
175    if (!IS_ERR(acl))
176        set_cached_acl(inode, type, acl);
177
178    return acl;
179}
180
181/*
182 * Set the access or default ACL of an inode.
183 *
184 * inode->i_mutex: down unless called from ext3_new_inode
185 */
186static int
187ext3_set_acl(handle_t *handle, struct inode *inode, int type,
188         struct posix_acl *acl)
189{
190    int name_index;
191    void *value = NULL;
192    size_t size = 0;
193    int error;
194
195    if (S_ISLNK(inode->i_mode))
196        return -EOPNOTSUPP;
197
198    switch(type) {
199        case ACL_TYPE_ACCESS:
200            name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
201            if (acl) {
202                mode_t mode = inode->i_mode;
203                error = posix_acl_equiv_mode(acl, &mode);
204                if (error < 0)
205                    return error;
206                else {
207                    inode->i_mode = mode;
208                    inode->i_ctime = CURRENT_TIME_SEC;
209                    ext3_mark_inode_dirty(handle, inode);
210                    if (error == 0)
211                        acl = NULL;
212                }
213            }
214            break;
215
216        case ACL_TYPE_DEFAULT:
217            name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
218            if (!S_ISDIR(inode->i_mode))
219                return acl ? -EACCES : 0;
220            break;
221
222        default:
223            return -EINVAL;
224    }
225    if (acl) {
226        value = ext3_acl_to_disk(acl, &size);
227        if (IS_ERR(value))
228            return (int)PTR_ERR(value);
229    }
230
231    error = ext3_xattr_set_handle(handle, inode, name_index, "",
232                      value, size, 0);
233
234    kfree(value);
235
236    if (!error)
237        set_cached_acl(inode, type, acl);
238
239    return error;
240}
241
242int
243ext3_check_acl(struct inode *inode, int mask, unsigned int flags)
244{
245    struct posix_acl *acl;
246
247    if (flags & IPERM_FLAG_RCU) {
248        if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
249            return -ECHILD;
250        return -EAGAIN;
251    }
252
253    acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
254    if (IS_ERR(acl))
255        return PTR_ERR(acl);
256    if (acl) {
257        int error = posix_acl_permission(inode, acl, mask);
258        posix_acl_release(acl);
259        return error;
260    }
261
262    return -EAGAIN;
263}
264
265/*
266 * Initialize the ACLs of a new inode. Called from ext3_new_inode.
267 *
268 * dir->i_mutex: down
269 * inode->i_mutex: up (access to inode is still exclusive)
270 */
271int
272ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
273{
274    struct posix_acl *acl = NULL;
275    int error = 0;
276
277    if (!S_ISLNK(inode->i_mode)) {
278        if (test_opt(dir->i_sb, POSIX_ACL)) {
279            acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
280            if (IS_ERR(acl))
281                return PTR_ERR(acl);
282        }
283        if (!acl)
284            inode->i_mode &= ~current_umask();
285    }
286    if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
287        struct posix_acl *clone;
288        mode_t mode;
289
290        if (S_ISDIR(inode->i_mode)) {
291            error = ext3_set_acl(handle, inode,
292                         ACL_TYPE_DEFAULT, acl);
293            if (error)
294                goto cleanup;
295        }
296        clone = posix_acl_clone(acl, GFP_NOFS);
297        error = -ENOMEM;
298        if (!clone)
299            goto cleanup;
300
301        mode = inode->i_mode;
302        error = posix_acl_create_masq(clone, &mode);
303        if (error >= 0) {
304            inode->i_mode = mode;
305            if (error > 0) {
306                /* This is an extended ACL */
307                error = ext3_set_acl(handle, inode,
308                             ACL_TYPE_ACCESS, clone);
309            }
310        }
311        posix_acl_release(clone);
312    }
313cleanup:
314    posix_acl_release(acl);
315    return error;
316}
317
318/*
319 * Does chmod for an inode that may have an Access Control List. The
320 * inode->i_mode field must be updated to the desired value by the caller
321 * before calling this function.
322 * Returns 0 on success, or a negative error number.
323 *
324 * We change the ACL rather than storing some ACL entries in the file
325 * mode permission bits (which would be more efficient), because that
326 * would break once additional permissions (like ACL_APPEND, ACL_DELETE
327 * for directories) are added. There are no more bits available in the
328 * file mode.
329 *
330 * inode->i_mutex: down
331 */
332int
333ext3_acl_chmod(struct inode *inode)
334{
335    struct posix_acl *acl, *clone;
336        int error;
337
338    if (S_ISLNK(inode->i_mode))
339        return -EOPNOTSUPP;
340    if (!test_opt(inode->i_sb, POSIX_ACL))
341        return 0;
342    acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
343    if (IS_ERR(acl) || !acl)
344        return PTR_ERR(acl);
345    clone = posix_acl_clone(acl, GFP_KERNEL);
346    posix_acl_release(acl);
347    if (!clone)
348        return -ENOMEM;
349    error = posix_acl_chmod_masq(clone, inode->i_mode);
350    if (!error) {
351        handle_t *handle;
352        int retries = 0;
353
354    retry:
355        handle = ext3_journal_start(inode,
356                EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
357        if (IS_ERR(handle)) {
358            error = PTR_ERR(handle);
359            ext3_std_error(inode->i_sb, error);
360            goto out;
361        }
362        error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
363        ext3_journal_stop(handle);
364        if (error == -ENOSPC &&
365            ext3_should_retry_alloc(inode->i_sb, &retries))
366            goto retry;
367    }
368out:
369    posix_acl_release(clone);
370    return error;
371}
372
373/*
374 * Extended attribute handlers
375 */
376static size_t
377ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
378               const char *name, size_t name_len, int type)
379{
380    const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
381
382    if (!test_opt(dentry->d_sb, POSIX_ACL))
383        return 0;
384    if (list && size <= list_len)
385        memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
386    return size;
387}
388
389static size_t
390ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
391                const char *name, size_t name_len, int type)
392{
393    const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
394
395    if (!test_opt(dentry->d_sb, POSIX_ACL))
396        return 0;
397    if (list && size <= list_len)
398        memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
399    return size;
400}
401
402static int
403ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
404           size_t size, int type)
405{
406    struct posix_acl *acl;
407    int error;
408
409    if (strcmp(name, "") != 0)
410        return -EINVAL;
411    if (!test_opt(dentry->d_sb, POSIX_ACL))
412        return -EOPNOTSUPP;
413
414    acl = ext3_get_acl(dentry->d_inode, type);
415    if (IS_ERR(acl))
416        return PTR_ERR(acl);
417    if (acl == NULL)
418        return -ENODATA;
419    error = posix_acl_to_xattr(acl, buffer, size);
420    posix_acl_release(acl);
421
422    return error;
423}
424
425static int
426ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
427           size_t size, int flags, int type)
428{
429    struct inode *inode = dentry->d_inode;
430    handle_t *handle;
431    struct posix_acl *acl;
432    int error, retries = 0;
433
434    if (strcmp(name, "") != 0)
435        return -EINVAL;
436    if (!test_opt(inode->i_sb, POSIX_ACL))
437        return -EOPNOTSUPP;
438    if (!inode_owner_or_capable(inode))
439        return -EPERM;
440
441    if (value) {
442        acl = posix_acl_from_xattr(value, size);
443        if (IS_ERR(acl))
444            return PTR_ERR(acl);
445        else if (acl) {
446            error = posix_acl_valid(acl);
447            if (error)
448                goto release_and_out;
449        }
450    } else
451        acl = NULL;
452
453retry:
454    handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
455    if (IS_ERR(handle))
456        return PTR_ERR(handle);
457    error = ext3_set_acl(handle, inode, type, acl);
458    ext3_journal_stop(handle);
459    if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
460        goto retry;
461
462release_and_out:
463    posix_acl_release(acl);
464    return error;
465}
466
467const struct xattr_handler ext3_xattr_acl_access_handler = {
468    .prefix = POSIX_ACL_XATTR_ACCESS,
469    .flags = ACL_TYPE_ACCESS,
470    .list = ext3_xattr_list_acl_access,
471    .get = ext3_xattr_get_acl,
472    .set = ext3_xattr_set_acl,
473};
474
475const struct xattr_handler ext3_xattr_acl_default_handler = {
476    .prefix = POSIX_ACL_XATTR_DEFAULT,
477    .flags = ACL_TYPE_DEFAULT,
478    .list = ext3_xattr_list_acl_default,
479    .get = ext3_xattr_get_acl,
480    .set = ext3_xattr_set_acl,
481};
482

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