1/*
2 * linux/fs/ext4/acl.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5 */
6
7#include "ext4_jbd2.h"
8#include "ext4.h"
9#include "xattr.h"
10#include "acl.h"
11
12/*
13 * Convert from filesystem to in-memory representation.
14 */
15static struct posix_acl *
16ext4_acl_from_disk(const void *value, size_t size)
17{
18	const char *end = (char *)value + size;
19	int n, count;
20	struct posix_acl *acl;
21
22	if (!value)
23		return NULL;
24	if (size < sizeof(ext4_acl_header))
25		 return ERR_PTR(-EINVAL);
26	if (((ext4_acl_header *)value)->a_version !=
27	    cpu_to_le32(EXT4_ACL_VERSION))
28		return ERR_PTR(-EINVAL);
29	value = (char *)value + sizeof(ext4_acl_header);
30	count = ext4_acl_count(size);
31	if (count < 0)
32		return ERR_PTR(-EINVAL);
33	if (count == 0)
34		return NULL;
35	acl = posix_acl_alloc(count, GFP_NOFS);
36	if (!acl)
37		return ERR_PTR(-ENOMEM);
38	for (n = 0; n < count; n++) {
39		ext4_acl_entry *entry =
40			(ext4_acl_entry *)value;
41		if ((char *)value + sizeof(ext4_acl_entry_short) > end)
42			goto fail;
43		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
44		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
45
46		switch (acl->a_entries[n].e_tag) {
47		case ACL_USER_OBJ:
48		case ACL_GROUP_OBJ:
49		case ACL_MASK:
50		case ACL_OTHER:
51			value = (char *)value +
52				sizeof(ext4_acl_entry_short);
53			break;
54
55		case ACL_USER:
56			value = (char *)value + sizeof(ext4_acl_entry);
57			if ((char *)value > end)
58				goto fail;
59			acl->a_entries[n].e_uid =
60				make_kuid(&init_user_ns,
61					  le32_to_cpu(entry->e_id));
62			break;
63		case ACL_GROUP:
64			value = (char *)value + sizeof(ext4_acl_entry);
65			if ((char *)value > end)
66				goto fail;
67			acl->a_entries[n].e_gid =
68				make_kgid(&init_user_ns,
69					  le32_to_cpu(entry->e_id));
70			break;
71
72		default:
73			goto fail;
74		}
75	}
76	if (value != end)
77		goto fail;
78	return acl;
79
80fail:
81	posix_acl_release(acl);
82	return ERR_PTR(-EINVAL);
83}
84
85/*
86 * Convert from in-memory to filesystem representation.
87 */
88static void *
89ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
90{
91	ext4_acl_header *ext_acl;
92	char *e;
93	size_t n;
94
95	*size = ext4_acl_size(acl->a_count);
96	ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
97			sizeof(ext4_acl_entry), GFP_NOFS);
98	if (!ext_acl)
99		return ERR_PTR(-ENOMEM);
100	ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
101	e = (char *)ext_acl + sizeof(ext4_acl_header);
102	for (n = 0; n < acl->a_count; n++) {
103		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
104		ext4_acl_entry *entry = (ext4_acl_entry *)e;
105		entry->e_tag  = cpu_to_le16(acl_e->e_tag);
106		entry->e_perm = cpu_to_le16(acl_e->e_perm);
107		switch (acl_e->e_tag) {
108		case ACL_USER:
109			entry->e_id = cpu_to_le32(
110				from_kuid(&init_user_ns, acl_e->e_uid));
111			e += sizeof(ext4_acl_entry);
112			break;
113		case ACL_GROUP:
114			entry->e_id = cpu_to_le32(
115				from_kgid(&init_user_ns, acl_e->e_gid));
116			e += sizeof(ext4_acl_entry);
117			break;
118
119		case ACL_USER_OBJ:
120		case ACL_GROUP_OBJ:
121		case ACL_MASK:
122		case ACL_OTHER:
123			e += sizeof(ext4_acl_entry_short);
124			break;
125
126		default:
127			goto fail;
128		}
129	}
130	return (char *)ext_acl;
131
132fail:
133	kfree(ext_acl);
134	return ERR_PTR(-EINVAL);
135}
136
137/*
138 * Inode operation get_posix_acl().
139 *
140 * inode->i_mutex: don't care
141 */
142struct posix_acl *
143ext4_get_acl(struct inode *inode, int type)
144{
145	int name_index;
146	char *value = NULL;
147	struct posix_acl *acl;
148	int retval;
149
150	switch (type) {
151	case ACL_TYPE_ACCESS:
152		name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
153		break;
154	case ACL_TYPE_DEFAULT:
155		name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
156		break;
157	default:
158		BUG();
159	}
160	retval = ext4_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 = ext4_xattr_get(inode, name_index, "", value, retval);
166	}
167	if (retval > 0)
168		acl = ext4_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 ext4_new_inode
185 */
186static int
187__ext4_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	switch (type) {
196	case ACL_TYPE_ACCESS:
197		name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
198		if (acl) {
199			error = posix_acl_equiv_mode(acl, &inode->i_mode);
200			if (error < 0)
201				return error;
202			else {
203				inode->i_ctime = ext4_current_time(inode);
204				ext4_mark_inode_dirty(handle, inode);
205				if (error == 0)
206					acl = NULL;
207			}
208		}
209		break;
210
211	case ACL_TYPE_DEFAULT:
212		name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
213		if (!S_ISDIR(inode->i_mode))
214			return acl ? -EACCES : 0;
215		break;
216
217	default:
218		return -EINVAL;
219	}
220	if (acl) {
221		value = ext4_acl_to_disk(acl, &size);
222		if (IS_ERR(value))
223			return (int)PTR_ERR(value);
224	}
225
226	error = ext4_xattr_set_handle(handle, inode, name_index, "",
227				      value, size, 0);
228
229	kfree(value);
230	if (!error)
231		set_cached_acl(inode, type, acl);
232
233	return error;
234}
235
236int
237ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
238{
239	handle_t *handle;
240	int error, retries = 0;
241
242retry:
243	handle = ext4_journal_start(inode, EXT4_HT_XATTR,
244				    ext4_jbd2_credits_xattr(inode));
245	if (IS_ERR(handle))
246		return PTR_ERR(handle);
247
248	error = __ext4_set_acl(handle, inode, type, acl);
249	ext4_journal_stop(handle);
250	if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
251		goto retry;
252	return error;
253}
254
255/*
256 * Initialize the ACLs of a new inode. Called from ext4_new_inode.
257 *
258 * dir->i_mutex: down
259 * inode->i_mutex: up (access to inode is still exclusive)
260 */
261int
262ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
263{
264	struct posix_acl *default_acl, *acl;
265	int error;
266
267	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
268	if (error)
269		return error;
270
271	if (default_acl) {
272		error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
273				       default_acl);
274		posix_acl_release(default_acl);
275	}
276	if (acl) {
277		if (!error)
278			error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
279					       acl);
280		posix_acl_release(acl);
281	}
282	return error;
283}
284