1/*
2 * linux/fs/ext2/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/fs.h>
11#include "ext2.h"
12#include "xattr.h"
13#include "acl.h"
14
15/*
16 * Convert from filesystem to in-memory representation.
17 */
18static struct posix_acl *
19ext2_acl_from_disk(const void *value, size_t size)
20{
21	const char *end = (char *)value + size;
22	int n, count;
23	struct posix_acl *acl;
24
25	if (!value)
26		return NULL;
27	if (size < sizeof(ext2_acl_header))
28		 return ERR_PTR(-EINVAL);
29	if (((ext2_acl_header *)value)->a_version !=
30	    cpu_to_le32(EXT2_ACL_VERSION))
31		return ERR_PTR(-EINVAL);
32	value = (char *)value + sizeof(ext2_acl_header);
33	count = ext2_acl_count(size);
34	if (count < 0)
35		return ERR_PTR(-EINVAL);
36	if (count == 0)
37		return NULL;
38	acl = posix_acl_alloc(count, GFP_KERNEL);
39	if (!acl)
40		return ERR_PTR(-ENOMEM);
41	for (n=0; n < count; n++) {
42		ext2_acl_entry *entry =
43			(ext2_acl_entry *)value;
44		if ((char *)value + sizeof(ext2_acl_entry_short) > end)
45			goto fail;
46		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
47		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
48		switch(acl->a_entries[n].e_tag) {
49			case ACL_USER_OBJ:
50			case ACL_GROUP_OBJ:
51			case ACL_MASK:
52			case ACL_OTHER:
53				value = (char *)value +
54					sizeof(ext2_acl_entry_short);
55				break;
56
57			case ACL_USER:
58				value = (char *)value + sizeof(ext2_acl_entry);
59				if ((char *)value > end)
60					goto fail;
61				acl->a_entries[n].e_uid =
62					make_kuid(&init_user_ns,
63						  le32_to_cpu(entry->e_id));
64				break;
65			case ACL_GROUP:
66				value = (char *)value + sizeof(ext2_acl_entry);
67				if ((char *)value > end)
68					goto fail;
69				acl->a_entries[n].e_gid =
70					make_kgid(&init_user_ns,
71						  le32_to_cpu(entry->e_id));
72				break;
73
74			default:
75				goto fail;
76		}
77	}
78	if (value != end)
79		goto fail;
80	return acl;
81
82fail:
83	posix_acl_release(acl);
84	return ERR_PTR(-EINVAL);
85}
86
87/*
88 * Convert from in-memory to filesystem representation.
89 */
90static void *
91ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
92{
93	ext2_acl_header *ext_acl;
94	char *e;
95	size_t n;
96
97	*size = ext2_acl_size(acl->a_count);
98	ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
99			sizeof(ext2_acl_entry), GFP_KERNEL);
100	if (!ext_acl)
101		return ERR_PTR(-ENOMEM);
102	ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
103	e = (char *)ext_acl + sizeof(ext2_acl_header);
104	for (n=0; n < acl->a_count; n++) {
105		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
106		ext2_acl_entry *entry = (ext2_acl_entry *)e;
107		entry->e_tag  = cpu_to_le16(acl_e->e_tag);
108		entry->e_perm = cpu_to_le16(acl_e->e_perm);
109		switch(acl_e->e_tag) {
110			case ACL_USER:
111				entry->e_id = cpu_to_le32(
112					from_kuid(&init_user_ns, acl_e->e_uid));
113				e += sizeof(ext2_acl_entry);
114				break;
115			case ACL_GROUP:
116				entry->e_id = cpu_to_le32(
117					from_kgid(&init_user_ns, acl_e->e_gid));
118				e += sizeof(ext2_acl_entry);
119				break;
120
121			case ACL_USER_OBJ:
122			case ACL_GROUP_OBJ:
123			case ACL_MASK:
124			case ACL_OTHER:
125				e += sizeof(ext2_acl_entry_short);
126				break;
127
128			default:
129				goto fail;
130		}
131	}
132	return (char *)ext_acl;
133
134fail:
135	kfree(ext_acl);
136	return ERR_PTR(-EINVAL);
137}
138
139/*
140 * inode->i_mutex: don't care
141 */
142struct posix_acl *
143ext2_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 = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
153		break;
154	case ACL_TYPE_DEFAULT:
155		name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
156		break;
157	default:
158		BUG();
159	}
160	retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
161	if (retval > 0) {
162		value = kmalloc(retval, GFP_KERNEL);
163		if (!value)
164			return ERR_PTR(-ENOMEM);
165		retval = ext2_xattr_get(inode, name_index, "", value, retval);
166	}
167	if (retval > 0)
168		acl = ext2_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 * inode->i_mutex: down
183 */
184int
185ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
186{
187	int name_index;
188	void *value = NULL;
189	size_t size = 0;
190	int error;
191
192	switch(type) {
193		case ACL_TYPE_ACCESS:
194			name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
195			if (acl) {
196				error = posix_acl_equiv_mode(acl, &inode->i_mode);
197				if (error < 0)
198					return error;
199				else {
200					inode->i_ctime = CURRENT_TIME_SEC;
201					mark_inode_dirty(inode);
202					if (error == 0)
203						acl = NULL;
204				}
205			}
206			break;
207
208		case ACL_TYPE_DEFAULT:
209			name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
210			if (!S_ISDIR(inode->i_mode))
211				return acl ? -EACCES : 0;
212			break;
213
214		default:
215			return -EINVAL;
216	}
217 	if (acl) {
218		value = ext2_acl_to_disk(acl, &size);
219		if (IS_ERR(value))
220			return (int)PTR_ERR(value);
221	}
222
223	error = ext2_xattr_set(inode, name_index, "", value, size, 0);
224
225	kfree(value);
226	if (!error)
227		set_cached_acl(inode, type, acl);
228	return error;
229}
230
231/*
232 * Initialize the ACLs of a new inode. Called from ext2_new_inode.
233 *
234 * dir->i_mutex: down
235 * inode->i_mutex: up (access to inode is still exclusive)
236 */
237int
238ext2_init_acl(struct inode *inode, struct inode *dir)
239{
240	struct posix_acl *default_acl, *acl;
241	int error;
242
243	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
244	if (error)
245		return error;
246
247	if (default_acl) {
248		error = ext2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
249		posix_acl_release(default_acl);
250	}
251	if (acl) {
252		if (!error)
253			error = ext2_set_acl(inode, acl, ACL_TYPE_ACCESS);
254		posix_acl_release(acl);
255	}
256	return error;
257}
258