1/*
  2 * linux/fs/ext3/acl.c
  3 *
  4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
  5 */
  6
  7#include "ext3.h"
  8#include "xattr.h"
  9#include "acl.h"
 10
 11/*
 12 * Convert from filesystem to in-memory representation.
 13 */
 14static struct posix_acl *
 15ext3_acl_from_disk(const void *value, size_t size)
 16{
 17	const char *end = (char *)value + size;
 18	int n, count;
 19	struct posix_acl *acl;
 20
 21	if (!value)
 22		return NULL;
 23	if (size < sizeof(ext3_acl_header))
 24		 return ERR_PTR(-EINVAL);
 25	if (((ext3_acl_header *)value)->a_version !=
 26	    cpu_to_le32(EXT3_ACL_VERSION))
 27		return ERR_PTR(-EINVAL);
 28	value = (char *)value + sizeof(ext3_acl_header);
 29	count = ext3_acl_count(size);
 30	if (count < 0)
 31		return ERR_PTR(-EINVAL);
 32	if (count == 0)
 33		return NULL;
 34	acl = posix_acl_alloc(count, GFP_NOFS);
 35	if (!acl)
 36		return ERR_PTR(-ENOMEM);
 37	for (n=0; n < count; n++) {
 38		ext3_acl_entry *entry =
 39			(ext3_acl_entry *)value;
 40		if ((char *)value + sizeof(ext3_acl_entry_short) > end)
 41			goto fail;
 42		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
 43		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
 44		switch(acl->a_entries[n].e_tag) {
 45			case ACL_USER_OBJ:
 46			case ACL_GROUP_OBJ:
 47			case ACL_MASK:
 48			case ACL_OTHER:
 49				value = (char *)value +
 50					sizeof(ext3_acl_entry_short);
 51				break;
 52
 53			case ACL_USER:
 54				value = (char *)value + sizeof(ext3_acl_entry);
 55				if ((char *)value > end)
 56					goto fail;
 57				acl->a_entries[n].e_uid =
 58					make_kuid(&init_user_ns,
 59						  le32_to_cpu(entry->e_id));
 60				break;
 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_gid =
 66					make_kgid(&init_user_ns,
 67						  le32_to_cpu(entry->e_id));
 68				break;
 69
 70			default:
 71				goto fail;
 72		}
 73	}
 74	if (value != end)
 75		goto fail;
 76	return acl;
 77
 78fail:
 79	posix_acl_release(acl);
 80	return ERR_PTR(-EINVAL);
 81}
 82
 83/*
 84 * Convert from in-memory to filesystem representation.
 85 */
 86static void *
 87ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
 88{
 89	ext3_acl_header *ext_acl;
 90	char *e;
 91	size_t n;
 92
 93	*size = ext3_acl_size(acl->a_count);
 94	ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
 95			sizeof(ext3_acl_entry), GFP_NOFS);
 96	if (!ext_acl)
 97		return ERR_PTR(-ENOMEM);
 98	ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
 99	e = (char *)ext_acl + sizeof(ext3_acl_header);
100	for (n=0; n < acl->a_count; n++) {
101		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
102		ext3_acl_entry *entry = (ext3_acl_entry *)e;
103		entry->e_tag  = cpu_to_le16(acl_e->e_tag);
104		entry->e_perm = cpu_to_le16(acl_e->e_perm);
105		switch(acl_e->e_tag) {
106			case ACL_USER:
107				entry->e_id = cpu_to_le32(
108					from_kuid(&init_user_ns, acl_e->e_uid));
109				e += sizeof(ext3_acl_entry);
110				break;
111			case ACL_GROUP:
112				entry->e_id = cpu_to_le32(
113					from_kgid(&init_user_ns, acl_e->e_gid));
114				e += sizeof(ext3_acl_entry);
115				break;
116
117			case ACL_USER_OBJ:
118			case ACL_GROUP_OBJ:
119			case ACL_MASK:
120			case ACL_OTHER:
121				e += sizeof(ext3_acl_entry_short);
122				break;
123
124			default:
125				goto fail;
126		}
127	}
128	return (char *)ext_acl;
129
130fail:
131	kfree(ext_acl);
132	return ERR_PTR(-EINVAL);
133}
134
135/*
136 * Inode operation get_posix_acl().
137 *
138 * inode->i_mutex: don't care
139 */
140struct posix_acl *
141ext3_get_acl(struct inode *inode, int type)
142{
143	int name_index;
144	char *value = NULL;
145	struct posix_acl *acl;
146	int retval;
147
148	switch (type) {
149	case ACL_TYPE_ACCESS:
150		name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
151		break;
152	case ACL_TYPE_DEFAULT:
153		name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
154		break;
155	default:
156		BUG();
157	}
158
159	retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
160	if (retval > 0) {
161		value = kmalloc(retval, GFP_NOFS);
162		if (!value)
163			return ERR_PTR(-ENOMEM);
164		retval = ext3_xattr_get(inode, name_index, "", value, retval);
165	}
166	if (retval > 0)
167		acl = ext3_acl_from_disk(value, retval);
168	else if (retval == -ENODATA || retval == -ENOSYS)
169		acl = NULL;
170	else
171		acl = ERR_PTR(retval);
172	kfree(value);
173
174	if (!IS_ERR(acl))
175		set_cached_acl(inode, type, acl);
176
177	return acl;
178}
179
180/*
181 * Set the access or default ACL of an inode.
182 *
183 * inode->i_mutex: down unless called from ext3_new_inode
184 */
185static int
186__ext3_set_acl(handle_t *handle, struct inode *inode, int type,
187	     struct posix_acl *acl)
188{
189	int name_index;
190	void *value = NULL;
191	size_t size = 0;
192	int error;
193
194	switch(type) {
195		case ACL_TYPE_ACCESS:
196			name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
197			if (acl) {
198				error = posix_acl_equiv_mode(acl, &inode->i_mode);
199				if (error < 0)
200					return error;
201				else {
202					inode->i_ctime = CURRENT_TIME_SEC;
203					ext3_mark_inode_dirty(handle, inode);
204					if (error == 0)
205						acl = NULL;
206				}
207			}
208			break;
209
210		case ACL_TYPE_DEFAULT:
211			name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
212			if (!S_ISDIR(inode->i_mode))
213				return acl ? -EACCES : 0;
214			break;
215
216		default:
217			return -EINVAL;
218	}
219	if (acl) {
220		value = ext3_acl_to_disk(acl, &size);
221		if (IS_ERR(value))
222			return (int)PTR_ERR(value);
223	}
224
225	error = ext3_xattr_set_handle(handle, inode, name_index, "",
226				      value, size, 0);
227
228	kfree(value);
229
230	if (!error)
231		set_cached_acl(inode, type, acl);
232
233	return error;
234}
235
236int
237ext3_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 = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
244	if (IS_ERR(handle))
245		return PTR_ERR(handle);
246	error = __ext3_set_acl(handle, inode, type, acl);
247	ext3_journal_stop(handle);
248	if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
249		goto retry;
250	return error;
251}
252
253/*
254 * Initialize the ACLs of a new inode. Called from ext3_new_inode.
255 *
256 * dir->i_mutex: down
257 * inode->i_mutex: up (access to inode is still exclusive)
258 */
259int
260ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
261{
262	struct posix_acl *default_acl, *acl;
263	int error;
264
265	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
266	if (error)
267		return error;
268
269	if (default_acl) {
270		error = __ext3_set_acl(handle, inode, ACL_TYPE_DEFAULT,
271				       default_acl);
272		posix_acl_release(default_acl);
273	}
274	if (acl) {
275		if (!error)
276			error = __ext3_set_acl(handle, inode, ACL_TYPE_ACCESS,
277					       acl);
278		posix_acl_release(acl);
279	}
280	return error;
281}