1/*
2 * Copyright (c) 2008, Christoph Hellwig
3 * All Rights Reserved.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17 */
18#include "xfs.h"
19#include "xfs_format.h"
20#include "xfs_log_format.h"
21#include "xfs_trans_resv.h"
22#include "xfs_mount.h"
23#include "xfs_inode.h"
24#include "xfs_acl.h"
25#include "xfs_attr.h"
26#include "xfs_trace.h"
27#include <linux/slab.h>
28#include <linux/xattr.h>
29#include <linux/posix_acl_xattr.h>
30
31
32/*
33 * Locking scheme:
34 *  - all ACL updates are protected by inode->i_mutex, which is taken before
35 *    calling into this file.
36 */
37
38STATIC struct posix_acl *
39xfs_acl_from_disk(
40	const struct xfs_acl	*aclp,
41	int			len,
42	int			max_entries)
43{
44	struct posix_acl_entry *acl_e;
45	struct posix_acl *acl;
46	const struct xfs_acl_entry *ace;
47	unsigned int count, i;
48
49	if (len < sizeof(*aclp))
50		return ERR_PTR(-EFSCORRUPTED);
51	count = be32_to_cpu(aclp->acl_cnt);
52	if (count > max_entries || XFS_ACL_SIZE(count) != len)
53		return ERR_PTR(-EFSCORRUPTED);
54
55	acl = posix_acl_alloc(count, GFP_KERNEL);
56	if (!acl)
57		return ERR_PTR(-ENOMEM);
58
59	for (i = 0; i < count; i++) {
60		acl_e = &acl->a_entries[i];
61		ace = &aclp->acl_entry[i];
62
63		/*
64		 * The tag is 32 bits on disk and 16 bits in core.
65		 *
66		 * Because every access to it goes through the core
67		 * format first this is not a problem.
68		 */
69		acl_e->e_tag = be32_to_cpu(ace->ae_tag);
70		acl_e->e_perm = be16_to_cpu(ace->ae_perm);
71
72		switch (acl_e->e_tag) {
73		case ACL_USER:
74			acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
75			break;
76		case ACL_GROUP:
77			acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
78			break;
79		case ACL_USER_OBJ:
80		case ACL_GROUP_OBJ:
81		case ACL_MASK:
82		case ACL_OTHER:
83			break;
84		default:
85			goto fail;
86		}
87	}
88	return acl;
89
90fail:
91	posix_acl_release(acl);
92	return ERR_PTR(-EINVAL);
93}
94
95STATIC void
96xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
97{
98	const struct posix_acl_entry *acl_e;
99	struct xfs_acl_entry *ace;
100	int i;
101
102	aclp->acl_cnt = cpu_to_be32(acl->a_count);
103	for (i = 0; i < acl->a_count; i++) {
104		ace = &aclp->acl_entry[i];
105		acl_e = &acl->a_entries[i];
106
107		ace->ae_tag = cpu_to_be32(acl_e->e_tag);
108		switch (acl_e->e_tag) {
109		case ACL_USER:
110			ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
111			break;
112		case ACL_GROUP:
113			ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
114			break;
115		default:
116			ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
117			break;
118		}
119
120		ace->ae_perm = cpu_to_be16(acl_e->e_perm);
121	}
122}
123
124struct posix_acl *
125xfs_get_acl(struct inode *inode, int type)
126{
127	struct xfs_inode *ip = XFS_I(inode);
128	struct posix_acl *acl = NULL;
129	struct xfs_acl *xfs_acl;
130	unsigned char *ea_name;
131	int error;
132	int len;
133
134	trace_xfs_get_acl(ip);
135
136	switch (type) {
137	case ACL_TYPE_ACCESS:
138		ea_name = SGI_ACL_FILE;
139		break;
140	case ACL_TYPE_DEFAULT:
141		ea_name = SGI_ACL_DEFAULT;
142		break;
143	default:
144		BUG();
145	}
146
147	/*
148	 * If we have a cached ACLs value just return it, not need to
149	 * go out to the disk.
150	 */
151	len = XFS_ACL_MAX_SIZE(ip->i_mount);
152	xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
153	if (!xfs_acl)
154		return ERR_PTR(-ENOMEM);
155
156	error = xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
157							&len, ATTR_ROOT);
158	if (error) {
159		/*
160		 * If the attribute doesn't exist make sure we have a negative
161		 * cache entry, for any other error assume it is transient and
162		 * leave the cache entry as ACL_NOT_CACHED.
163		 */
164		if (error == -ENOATTR)
165			goto out_update_cache;
166		acl = ERR_PTR(error);
167		goto out;
168	}
169
170	acl = xfs_acl_from_disk(xfs_acl, len, XFS_ACL_MAX_ENTRIES(ip->i_mount));
171	if (IS_ERR(acl))
172		goto out;
173
174out_update_cache:
175	set_cached_acl(inode, type, acl);
176out:
177	kmem_free(xfs_acl);
178	return acl;
179}
180
181STATIC int
182__xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
183{
184	struct xfs_inode *ip = XFS_I(inode);
185	unsigned char *ea_name;
186	int error;
187
188	switch (type) {
189	case ACL_TYPE_ACCESS:
190		ea_name = SGI_ACL_FILE;
191		break;
192	case ACL_TYPE_DEFAULT:
193		if (!S_ISDIR(inode->i_mode))
194			return acl ? -EACCES : 0;
195		ea_name = SGI_ACL_DEFAULT;
196		break;
197	default:
198		return -EINVAL;
199	}
200
201	if (acl) {
202		struct xfs_acl *xfs_acl;
203		int len = XFS_ACL_MAX_SIZE(ip->i_mount);
204
205		xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
206		if (!xfs_acl)
207			return -ENOMEM;
208
209		xfs_acl_to_disk(xfs_acl, acl);
210
211		/* subtract away the unused acl entries */
212		len -= sizeof(struct xfs_acl_entry) *
213			 (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
214
215		error = xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
216				len, ATTR_ROOT);
217
218		kmem_free(xfs_acl);
219	} else {
220		/*
221		 * A NULL ACL argument means we want to remove the ACL.
222		 */
223		error = xfs_attr_remove(ip, ea_name, ATTR_ROOT);
224
225		/*
226		 * If the attribute didn't exist to start with that's fine.
227		 */
228		if (error == -ENOATTR)
229			error = 0;
230	}
231
232	if (!error)
233		set_cached_acl(inode, type, acl);
234	return error;
235}
236
237static int
238xfs_set_mode(struct inode *inode, umode_t mode)
239{
240	int error = 0;
241
242	if (mode != inode->i_mode) {
243		struct iattr iattr;
244
245		iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
246		iattr.ia_mode = mode;
247		iattr.ia_ctime = current_fs_time(inode->i_sb);
248
249		error = xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
250	}
251
252	return error;
253}
254
255static int
256xfs_acl_exists(struct inode *inode, unsigned char *name)
257{
258	int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
259
260	return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
261			    ATTR_ROOT|ATTR_KERNOVAL) == 0);
262}
263
264int
265posix_acl_access_exists(struct inode *inode)
266{
267	return xfs_acl_exists(inode, SGI_ACL_FILE);
268}
269
270int
271posix_acl_default_exists(struct inode *inode)
272{
273	if (!S_ISDIR(inode->i_mode))
274		return 0;
275	return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
276}
277
278int
279xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
280{
281	int error = 0;
282
283	if (!acl)
284		goto set_acl;
285
286	error = -E2BIG;
287	if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
288		return error;
289
290	if (type == ACL_TYPE_ACCESS) {
291		umode_t mode = inode->i_mode;
292		error = posix_acl_equiv_mode(acl, &mode);
293
294		if (error <= 0) {
295			acl = NULL;
296
297			if (error < 0)
298				return error;
299		}
300
301		error = xfs_set_mode(inode, mode);
302		if (error)
303			return error;
304	}
305
306 set_acl:
307	return __xfs_set_acl(inode, type, acl);
308}
309