1/*
  2 * fs/f2fs/acl.c
  3 *
  4 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
  5 *             http://www.samsung.com/
  6 *
  7 * Portions of this code from linux/fs/ext2/acl.c
  8 *
  9 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
 10 *
 11 * This program is free software; you can redistribute it and/or modify
 12 * it under the terms of the GNU General Public License version 2 as
 13 * published by the Free Software Foundation.
 14 */
 15#include <linux/f2fs_fs.h>
 16#include "f2fs.h"
 17#include "xattr.h"
 18#include "acl.h"
 19
 20static inline size_t f2fs_acl_size(int count)
 21{
 22	if (count <= 4) {
 23		return sizeof(struct f2fs_acl_header) +
 24			count * sizeof(struct f2fs_acl_entry_short);
 25	} else {
 26		return sizeof(struct f2fs_acl_header) +
 27			4 * sizeof(struct f2fs_acl_entry_short) +
 28			(count - 4) * sizeof(struct f2fs_acl_entry);
 29	}
 30}
 31
 32static inline int f2fs_acl_count(size_t size)
 33{
 34	ssize_t s;
 35	size -= sizeof(struct f2fs_acl_header);
 36	s = size - 4 * sizeof(struct f2fs_acl_entry_short);
 37	if (s < 0) {
 38		if (size % sizeof(struct f2fs_acl_entry_short))
 39			return -1;
 40		return size / sizeof(struct f2fs_acl_entry_short);
 41	} else {
 42		if (s % sizeof(struct f2fs_acl_entry))
 43			return -1;
 44		return s / sizeof(struct f2fs_acl_entry) + 4;
 45	}
 46}
 47
 48static struct posix_acl *f2fs_acl_from_disk(const char *value, size_t size)
 49{
 50	int i, count;
 51	struct posix_acl *acl;
 52	struct f2fs_acl_header *hdr = (struct f2fs_acl_header *)value;
 53	struct f2fs_acl_entry *entry = (struct f2fs_acl_entry *)(hdr + 1);
 54	const char *end = value + size;
 55
 56	if (hdr->a_version != cpu_to_le32(F2FS_ACL_VERSION))
 57		return ERR_PTR(-EINVAL);
 58
 59	count = f2fs_acl_count(size);
 60	if (count < 0)
 61		return ERR_PTR(-EINVAL);
 62	if (count == 0)
 63		return NULL;
 64
 65	acl = posix_acl_alloc(count, GFP_NOFS);
 66	if (!acl)
 67		return ERR_PTR(-ENOMEM);
 68
 69	for (i = 0; i < count; i++) {
 70
 71		if ((char *)entry > end)
 72			goto fail;
 73
 74		acl->a_entries[i].e_tag  = le16_to_cpu(entry->e_tag);
 75		acl->a_entries[i].e_perm = le16_to_cpu(entry->e_perm);
 76
 77		switch (acl->a_entries[i].e_tag) {
 78		case ACL_USER_OBJ:
 79		case ACL_GROUP_OBJ:
 80		case ACL_MASK:
 81		case ACL_OTHER:
 82			entry = (struct f2fs_acl_entry *)((char *)entry +
 83					sizeof(struct f2fs_acl_entry_short));
 84			break;
 85
 86		case ACL_USER:
 87			acl->a_entries[i].e_uid =
 88				make_kuid(&init_user_ns,
 89						le32_to_cpu(entry->e_id));
 90			entry = (struct f2fs_acl_entry *)((char *)entry +
 91					sizeof(struct f2fs_acl_entry));
 92			break;
 93		case ACL_GROUP:
 94			acl->a_entries[i].e_gid =
 95				make_kgid(&init_user_ns,
 96						le32_to_cpu(entry->e_id));
 97			entry = (struct f2fs_acl_entry *)((char *)entry +
 98					sizeof(struct f2fs_acl_entry));
 99			break;
100		default:
101			goto fail;
102		}
103	}
104	if ((char *)entry != end)
105		goto fail;
106	return acl;
107fail:
108	posix_acl_release(acl);
109	return ERR_PTR(-EINVAL);
110}
111
112static void *f2fs_acl_to_disk(struct f2fs_sb_info *sbi,
113				const struct posix_acl *acl, size_t *size)
114{
115	struct f2fs_acl_header *f2fs_acl;
116	struct f2fs_acl_entry *entry;
117	int i;
118
119	f2fs_acl = f2fs_kmalloc(sbi, sizeof(struct f2fs_acl_header) +
120			acl->a_count * sizeof(struct f2fs_acl_entry),
121			GFP_NOFS);
122	if (!f2fs_acl)
123		return ERR_PTR(-ENOMEM);
124
125	f2fs_acl->a_version = cpu_to_le32(F2FS_ACL_VERSION);
126	entry = (struct f2fs_acl_entry *)(f2fs_acl + 1);
127
128	for (i = 0; i < acl->a_count; i++) {
129
130		entry->e_tag  = cpu_to_le16(acl->a_entries[i].e_tag);
131		entry->e_perm = cpu_to_le16(acl->a_entries[i].e_perm);
132
133		switch (acl->a_entries[i].e_tag) {
134		case ACL_USER:
135			entry->e_id = cpu_to_le32(
136					from_kuid(&init_user_ns,
137						acl->a_entries[i].e_uid));
138			entry = (struct f2fs_acl_entry *)((char *)entry +
139					sizeof(struct f2fs_acl_entry));
140			break;
141		case ACL_GROUP:
142			entry->e_id = cpu_to_le32(
143					from_kgid(&init_user_ns,
144						acl->a_entries[i].e_gid));
145			entry = (struct f2fs_acl_entry *)((char *)entry +
146					sizeof(struct f2fs_acl_entry));
147			break;
148		case ACL_USER_OBJ:
149		case ACL_GROUP_OBJ:
150		case ACL_MASK:
151		case ACL_OTHER:
152			entry = (struct f2fs_acl_entry *)((char *)entry +
153					sizeof(struct f2fs_acl_entry_short));
154			break;
155		default:
156			goto fail;
157		}
158	}
159	*size = f2fs_acl_size(acl->a_count);
160	return (void *)f2fs_acl;
161
162fail:
163	kfree(f2fs_acl);
164	return ERR_PTR(-EINVAL);
165}
166
167static struct posix_acl *__f2fs_get_acl(struct inode *inode, int type,
168						struct page *dpage)
169{
170	int name_index = F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT;
171	void *value = NULL;
172	struct posix_acl *acl;
173	int retval;
174
175	if (type == ACL_TYPE_ACCESS)
176		name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;
177
178	retval = f2fs_getxattr(inode, name_index, "", NULL, 0, dpage);
179	if (retval > 0) {
180		value = f2fs_kmalloc(F2FS_I_SB(inode), retval, GFP_F2FS_ZERO);
181		if (!value)
182			return ERR_PTR(-ENOMEM);
183		retval = f2fs_getxattr(inode, name_index, "", value,
184							retval, dpage);
185	}
186
187	if (retval > 0)
188		acl = f2fs_acl_from_disk(value, retval);
189	else if (retval == -ENODATA)
190		acl = NULL;
191	else
192		acl = ERR_PTR(retval);
193	kfree(value);
194
195	return acl;
196}
197
198struct posix_acl *f2fs_get_acl(struct inode *inode, int type)
199{
200	return __f2fs_get_acl(inode, type, NULL);
201}
202
203static int __f2fs_set_acl(struct inode *inode, int type,
204			struct posix_acl *acl, struct page *ipage)
205{
206	int name_index;
207	void *value = NULL;
208	size_t size = 0;
209	int error;
210	umode_t mode = inode->i_mode;
211
212	switch (type) {
213	case ACL_TYPE_ACCESS:
214		name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;
215		if (acl && !ipage) {
216			error = posix_acl_update_mode(inode, &mode, &acl);
217			if (error)
218				return error;
219			set_acl_inode(inode, mode);
220		}
221		break;
222
223	case ACL_TYPE_DEFAULT:
224		name_index = F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT;
225		if (!S_ISDIR(inode->i_mode))
226			return acl ? -EACCES : 0;
227		break;
228
229	default:
230		return -EINVAL;
231	}
232
233	if (acl) {
234		value = f2fs_acl_to_disk(F2FS_I_SB(inode), acl, &size);
235		if (IS_ERR(value)) {
236			clear_inode_flag(inode, FI_ACL_MODE);
237			return PTR_ERR(value);
238		}
239	}
240
241	error = f2fs_setxattr(inode, name_index, "", value, size, ipage, 0);
242
243	kfree(value);
244	if (!error)
245		set_cached_acl(inode, type, acl);
246
247	clear_inode_flag(inode, FI_ACL_MODE);
248	return error;
249}
250
251int f2fs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
252{
253	if (unlikely(f2fs_cp_error(F2FS_I_SB(inode))))
254		return -EIO;
255
256	return __f2fs_set_acl(inode, type, acl, NULL);
257}
258
259/*
260 * Most part of f2fs_acl_clone, f2fs_acl_create_masq, f2fs_acl_create
261 * are copied from posix_acl.c
262 */
263static struct posix_acl *f2fs_acl_clone(const struct posix_acl *acl,
264							gfp_t flags)
265{
266	struct posix_acl *clone = NULL;
267
268	if (acl) {
269		int size = sizeof(struct posix_acl) + acl->a_count *
270				sizeof(struct posix_acl_entry);
271		clone = kmemdup(acl, size, flags);
272		if (clone)
273			refcount_set(&clone->a_refcount, 1);
274	}
275	return clone;
276}
277
278static int f2fs_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
279{
280	struct posix_acl_entry *pa, *pe;
281	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
282	umode_t mode = *mode_p;
283	int not_equiv = 0;
284
285	/* assert(atomic_read(acl->a_refcount) == 1); */
286
287	FOREACH_ACL_ENTRY(pa, acl, pe) {
288		switch(pa->e_tag) {
289		case ACL_USER_OBJ:
290			pa->e_perm &= (mode >> 6) | ~S_IRWXO;
291			mode &= (pa->e_perm << 6) | ~S_IRWXU;
292			break;
293
294		case ACL_USER:
295		case ACL_GROUP:
296			not_equiv = 1;
297			break;
298
299		case ACL_GROUP_OBJ:
300			group_obj = pa;
301			break;
302
303		case ACL_OTHER:
304			pa->e_perm &= mode | ~S_IRWXO;
305			mode &= pa->e_perm | ~S_IRWXO;
306			break;
307
308		case ACL_MASK:
309			mask_obj = pa;
310			not_equiv = 1;
311			break;
312
313		default:
314			return -EIO;
315		}
316	}
317
318	if (mask_obj) {
319		mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
320		mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
321	} else {
322		if (!group_obj)
323			return -EIO;
324		group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
325		mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
326	}
327
328	*mode_p = (*mode_p & ~S_IRWXUGO) | mode;
329        return not_equiv;
330}
331
332static int f2fs_acl_create(struct inode *dir, umode_t *mode,
333		struct posix_acl **default_acl, struct posix_acl **acl,
334		struct page *dpage)
335{
336	struct posix_acl *p;
337	struct posix_acl *clone;
338	int ret;
339
340	*acl = NULL;
341	*default_acl = NULL;
342
343	if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
344		return 0;
345
346	p = __f2fs_get_acl(dir, ACL_TYPE_DEFAULT, dpage);
347	if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
348		*mode &= ~current_umask();
349		return 0;
350	}
351	if (IS_ERR(p))
352		return PTR_ERR(p);
353
354	clone = f2fs_acl_clone(p, GFP_NOFS);
355	if (!clone)
356		goto no_mem;
357
358	ret = f2fs_acl_create_masq(clone, mode);
359	if (ret < 0)
360		goto no_mem_clone;
361
362	if (ret == 0)
363		posix_acl_release(clone);
364	else
365		*acl = clone;
366
367	if (!S_ISDIR(*mode))
368		posix_acl_release(p);
369	else
370		*default_acl = p;
371
372	return 0;
373
374no_mem_clone:
375	posix_acl_release(clone);
376no_mem:
377	posix_acl_release(p);
378	return -ENOMEM;
379}
380
381int f2fs_init_acl(struct inode *inode, struct inode *dir, struct page *ipage,
382							struct page *dpage)
383{
384	struct posix_acl *default_acl = NULL, *acl = NULL;
385	int error = 0;
386
387	error = f2fs_acl_create(dir, &inode->i_mode, &default_acl, &acl, dpage);
388	if (error)
389		return error;
390
391	f2fs_mark_inode_dirty_sync(inode, true);
392
393	if (default_acl) {
394		error = __f2fs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl,
395				       ipage);
396		posix_acl_release(default_acl);
397	}
398	if (acl) {
399		if (!error)
400			error = __f2fs_set_acl(inode, ACL_TYPE_ACCESS, acl,
401					       ipage);
402		posix_acl_release(acl);
403	}
404
405	return error;
406}