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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2017-2018 HUAWEI, Inc.
4 * https://www.huawei.com/
5 * Copyright (C) 2021-2022, Alibaba Cloud
6 */
7#include <linux/security.h>
8#include <linux/xxhash.h>
9#include "xattr.h"
10
11struct erofs_xattr_iter {
12 struct super_block *sb;
13 struct erofs_buf buf;
14 erofs_off_t pos;
15 void *kaddr;
16
17 char *buffer;
18 int buffer_size, buffer_ofs;
19
20 /* getxattr */
21 int index, infix_len;
22 struct qstr name;
23
24 /* listxattr */
25 struct dentry *dentry;
26};
27
28static int erofs_init_inode_xattrs(struct inode *inode)
29{
30 struct erofs_inode *const vi = EROFS_I(inode);
31 struct erofs_xattr_iter it;
32 unsigned int i;
33 struct erofs_xattr_ibody_header *ih;
34 struct super_block *sb = inode->i_sb;
35 int ret = 0;
36
37 /* the most case is that xattrs of this inode are initialized. */
38 if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags)) {
39 /*
40 * paired with smp_mb() at the end of the function to ensure
41 * fields will only be observed after the bit is set.
42 */
43 smp_mb();
44 return 0;
45 }
46
47 if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_XATTR_BIT, TASK_KILLABLE))
48 return -ERESTARTSYS;
49
50 /* someone has initialized xattrs for us? */
51 if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags))
52 goto out_unlock;
53
54 /*
55 * bypass all xattr operations if ->xattr_isize is not greater than
56 * sizeof(struct erofs_xattr_ibody_header), in detail:
57 * 1) it is not enough to contain erofs_xattr_ibody_header then
58 * ->xattr_isize should be 0 (it means no xattr);
59 * 2) it is just to contain erofs_xattr_ibody_header, which is on-disk
60 * undefined right now (maybe use later with some new sb feature).
61 */
62 if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {
63 erofs_err(sb,
64 "xattr_isize %d of nid %llu is not supported yet",
65 vi->xattr_isize, vi->nid);
66 ret = -EOPNOTSUPP;
67 goto out_unlock;
68 } else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
69 if (vi->xattr_isize) {
70 erofs_err(sb, "bogus xattr ibody @ nid %llu", vi->nid);
71 DBG_BUGON(1);
72 ret = -EFSCORRUPTED;
73 goto out_unlock; /* xattr ondisk layout error */
74 }
75 ret = -ENOATTR;
76 goto out_unlock;
77 }
78
79 it.buf = __EROFS_BUF_INITIALIZER;
80 erofs_init_metabuf(&it.buf, sb);
81 it.pos = erofs_iloc(inode) + vi->inode_isize;
82
83 /* read in shared xattr array (non-atomic, see kmalloc below) */
84 it.kaddr = erofs_bread(&it.buf, it.pos, EROFS_KMAP);
85 if (IS_ERR(it.kaddr)) {
86 ret = PTR_ERR(it.kaddr);
87 goto out_unlock;
88 }
89
90 ih = it.kaddr;
91 vi->xattr_name_filter = le32_to_cpu(ih->h_name_filter);
92 vi->xattr_shared_count = ih->h_shared_count;
93 vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
94 sizeof(uint), GFP_KERNEL);
95 if (!vi->xattr_shared_xattrs) {
96 erofs_put_metabuf(&it.buf);
97 ret = -ENOMEM;
98 goto out_unlock;
99 }
100
101 /* let's skip ibody header */
102 it.pos += sizeof(struct erofs_xattr_ibody_header);
103
104 for (i = 0; i < vi->xattr_shared_count; ++i) {
105 it.kaddr = erofs_bread(&it.buf, it.pos, EROFS_KMAP);
106 if (IS_ERR(it.kaddr)) {
107 kfree(vi->xattr_shared_xattrs);
108 vi->xattr_shared_xattrs = NULL;
109 ret = PTR_ERR(it.kaddr);
110 goto out_unlock;
111 }
112 vi->xattr_shared_xattrs[i] = le32_to_cpu(*(__le32 *)it.kaddr);
113 it.pos += sizeof(__le32);
114 }
115 erofs_put_metabuf(&it.buf);
116
117 /* paired with smp_mb() at the beginning of the function. */
118 smp_mb();
119 set_bit(EROFS_I_EA_INITED_BIT, &vi->flags);
120
121out_unlock:
122 clear_and_wake_up_bit(EROFS_I_BL_XATTR_BIT, &vi->flags);
123 return ret;
124}
125
126static bool erofs_xattr_user_list(struct dentry *dentry)
127{
128 return test_opt(&EROFS_SB(dentry->d_sb)->opt, XATTR_USER);
129}
130
131static bool erofs_xattr_trusted_list(struct dentry *dentry)
132{
133 return capable(CAP_SYS_ADMIN);
134}
135
136static int erofs_xattr_generic_get(const struct xattr_handler *handler,
137 struct dentry *unused, struct inode *inode,
138 const char *name, void *buffer, size_t size)
139{
140 if (handler->flags == EROFS_XATTR_INDEX_USER &&
141 !test_opt(&EROFS_I_SB(inode)->opt, XATTR_USER))
142 return -EOPNOTSUPP;
143
144 return erofs_getxattr(inode, handler->flags, name, buffer, size);
145}
146
147const struct xattr_handler erofs_xattr_user_handler = {
148 .prefix = XATTR_USER_PREFIX,
149 .flags = EROFS_XATTR_INDEX_USER,
150 .list = erofs_xattr_user_list,
151 .get = erofs_xattr_generic_get,
152};
153
154const struct xattr_handler erofs_xattr_trusted_handler = {
155 .prefix = XATTR_TRUSTED_PREFIX,
156 .flags = EROFS_XATTR_INDEX_TRUSTED,
157 .list = erofs_xattr_trusted_list,
158 .get = erofs_xattr_generic_get,
159};
160
161#ifdef CONFIG_EROFS_FS_SECURITY
162const struct xattr_handler __maybe_unused erofs_xattr_security_handler = {
163 .prefix = XATTR_SECURITY_PREFIX,
164 .flags = EROFS_XATTR_INDEX_SECURITY,
165 .get = erofs_xattr_generic_get,
166};
167#endif
168
169const struct xattr_handler * const erofs_xattr_handlers[] = {
170 &erofs_xattr_user_handler,
171 &erofs_xattr_trusted_handler,
172#ifdef CONFIG_EROFS_FS_SECURITY
173 &erofs_xattr_security_handler,
174#endif
175 NULL,
176};
177
178static int erofs_xattr_copy_to_buffer(struct erofs_xattr_iter *it,
179 unsigned int len)
180{
181 unsigned int slice, processed;
182 struct super_block *sb = it->sb;
183 void *src;
184
185 for (processed = 0; processed < len; processed += slice) {
186 it->kaddr = erofs_bread(&it->buf, it->pos, EROFS_KMAP);
187 if (IS_ERR(it->kaddr))
188 return PTR_ERR(it->kaddr);
189
190 src = it->kaddr;
191 slice = min_t(unsigned int, sb->s_blocksize -
192 erofs_blkoff(sb, it->pos), len - processed);
193 memcpy(it->buffer + it->buffer_ofs, src, slice);
194 it->buffer_ofs += slice;
195 it->pos += slice;
196 }
197 return 0;
198}
199
200static int erofs_listxattr_foreach(struct erofs_xattr_iter *it)
201{
202 struct erofs_xattr_entry entry;
203 unsigned int base_index, name_total, prefix_len, infix_len = 0;
204 const char *prefix, *infix = NULL;
205 int err;
206
207 /* 1. handle xattr entry */
208 entry = *(struct erofs_xattr_entry *)it->kaddr;
209 it->pos += sizeof(struct erofs_xattr_entry);
210
211 base_index = entry.e_name_index;
212 if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
213 struct erofs_sb_info *sbi = EROFS_SB(it->sb);
214 struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
215 (entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
216
217 if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
218 return 0;
219 infix = pf->prefix->infix;
220 infix_len = pf->infix_len;
221 base_index = pf->prefix->base_index;
222 }
223
224 prefix = erofs_xattr_prefix(base_index, it->dentry);
225 if (!prefix)
226 return 0;
227 prefix_len = strlen(prefix);
228 name_total = prefix_len + infix_len + entry.e_name_len + 1;
229
230 if (!it->buffer) {
231 it->buffer_ofs += name_total;
232 return 0;
233 }
234
235 if (it->buffer_ofs + name_total > it->buffer_size)
236 return -ERANGE;
237
238 memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len);
239 memcpy(it->buffer + it->buffer_ofs + prefix_len, infix, infix_len);
240 it->buffer_ofs += prefix_len + infix_len;
241
242 /* 2. handle xattr name */
243 err = erofs_xattr_copy_to_buffer(it, entry.e_name_len);
244 if (err)
245 return err;
246
247 it->buffer[it->buffer_ofs++] = '\0';
248 return 0;
249}
250
251static int erofs_getxattr_foreach(struct erofs_xattr_iter *it)
252{
253 struct super_block *sb = it->sb;
254 struct erofs_xattr_entry entry;
255 unsigned int slice, processed, value_sz;
256
257 /* 1. handle xattr entry */
258 entry = *(struct erofs_xattr_entry *)it->kaddr;
259 it->pos += sizeof(struct erofs_xattr_entry);
260 value_sz = le16_to_cpu(entry.e_value_size);
261
262 /* should also match the infix for long name prefixes */
263 if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
264 struct erofs_sb_info *sbi = EROFS_SB(sb);
265 struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
266 (entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
267
268 if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
269 return -ENOATTR;
270
271 if (it->index != pf->prefix->base_index ||
272 it->name.len != entry.e_name_len + pf->infix_len)
273 return -ENOATTR;
274
275 if (memcmp(it->name.name, pf->prefix->infix, pf->infix_len))
276 return -ENOATTR;
277
278 it->infix_len = pf->infix_len;
279 } else {
280 if (it->index != entry.e_name_index ||
281 it->name.len != entry.e_name_len)
282 return -ENOATTR;
283
284 it->infix_len = 0;
285 }
286
287 /* 2. handle xattr name */
288 for (processed = 0; processed < entry.e_name_len; processed += slice) {
289 it->kaddr = erofs_bread(&it->buf, it->pos, EROFS_KMAP);
290 if (IS_ERR(it->kaddr))
291 return PTR_ERR(it->kaddr);
292
293 slice = min_t(unsigned int,
294 sb->s_blocksize - erofs_blkoff(sb, it->pos),
295 entry.e_name_len - processed);
296 if (memcmp(it->name.name + it->infix_len + processed,
297 it->kaddr, slice))
298 return -ENOATTR;
299 it->pos += slice;
300 }
301
302 /* 3. handle xattr value */
303 if (!it->buffer) {
304 it->buffer_ofs = value_sz;
305 return 0;
306 }
307
308 if (it->buffer_size < value_sz)
309 return -ERANGE;
310
311 return erofs_xattr_copy_to_buffer(it, value_sz);
312}
313
314static int erofs_xattr_iter_inline(struct erofs_xattr_iter *it,
315 struct inode *inode, bool getxattr)
316{
317 struct erofs_inode *const vi = EROFS_I(inode);
318 unsigned int xattr_header_sz, remaining, entry_sz;
319 erofs_off_t next_pos;
320 int ret;
321
322 xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
323 sizeof(u32) * vi->xattr_shared_count;
324 if (xattr_header_sz >= vi->xattr_isize) {
325 DBG_BUGON(xattr_header_sz > vi->xattr_isize);
326 return -ENOATTR;
327 }
328
329 remaining = vi->xattr_isize - xattr_header_sz;
330 it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
331
332 while (remaining) {
333 it->kaddr = erofs_bread(&it->buf, it->pos, EROFS_KMAP);
334 if (IS_ERR(it->kaddr))
335 return PTR_ERR(it->kaddr);
336
337 entry_sz = erofs_xattr_entry_size(it->kaddr);
338 /* xattr on-disk corruption: xattr entry beyond xattr_isize */
339 if (remaining < entry_sz) {
340 DBG_BUGON(1);
341 return -EFSCORRUPTED;
342 }
343 remaining -= entry_sz;
344 next_pos = it->pos + entry_sz;
345
346 if (getxattr)
347 ret = erofs_getxattr_foreach(it);
348 else
349 ret = erofs_listxattr_foreach(it);
350 if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
351 break;
352
353 it->pos = next_pos;
354 }
355 return ret;
356}
357
358static int erofs_xattr_iter_shared(struct erofs_xattr_iter *it,
359 struct inode *inode, bool getxattr)
360{
361 struct erofs_inode *const vi = EROFS_I(inode);
362 struct super_block *const sb = it->sb;
363 struct erofs_sb_info *sbi = EROFS_SB(sb);
364 unsigned int i;
365 int ret = -ENOATTR;
366
367 for (i = 0; i < vi->xattr_shared_count; ++i) {
368 it->pos = erofs_pos(sb, sbi->xattr_blkaddr) +
369 vi->xattr_shared_xattrs[i] * sizeof(__le32);
370 it->kaddr = erofs_bread(&it->buf, it->pos, EROFS_KMAP);
371 if (IS_ERR(it->kaddr))
372 return PTR_ERR(it->kaddr);
373
374 if (getxattr)
375 ret = erofs_getxattr_foreach(it);
376 else
377 ret = erofs_listxattr_foreach(it);
378 if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
379 break;
380 }
381 return ret;
382}
383
384int erofs_getxattr(struct inode *inode, int index, const char *name,
385 void *buffer, size_t buffer_size)
386{
387 int ret;
388 unsigned int hashbit;
389 struct erofs_xattr_iter it;
390 struct erofs_inode *vi = EROFS_I(inode);
391 struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
392
393 if (!name)
394 return -EINVAL;
395
396 ret = erofs_init_inode_xattrs(inode);
397 if (ret)
398 return ret;
399
400 /* reserved flag is non-zero if there's any change of on-disk format */
401 if (erofs_sb_has_xattr_filter(sbi) && !sbi->xattr_filter_reserved) {
402 hashbit = xxh32(name, strlen(name),
403 EROFS_XATTR_FILTER_SEED + index);
404 hashbit &= EROFS_XATTR_FILTER_BITS - 1;
405 if (vi->xattr_name_filter & (1U << hashbit))
406 return -ENOATTR;
407 }
408
409 it.index = index;
410 it.name = (struct qstr)QSTR_INIT(name, strlen(name));
411 if (it.name.len > EROFS_NAME_LEN)
412 return -ERANGE;
413
414 it.sb = inode->i_sb;
415 it.buf = __EROFS_BUF_INITIALIZER;
416 erofs_init_metabuf(&it.buf, it.sb);
417 it.buffer = buffer;
418 it.buffer_size = buffer_size;
419 it.buffer_ofs = 0;
420
421 ret = erofs_xattr_iter_inline(&it, inode, true);
422 if (ret == -ENOATTR)
423 ret = erofs_xattr_iter_shared(&it, inode, true);
424 erofs_put_metabuf(&it.buf);
425 return ret ? ret : it.buffer_ofs;
426}
427
428ssize_t erofs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
429{
430 int ret;
431 struct erofs_xattr_iter it;
432 struct inode *inode = d_inode(dentry);
433
434 ret = erofs_init_inode_xattrs(inode);
435 if (ret == -ENOATTR)
436 return 0;
437 if (ret)
438 return ret;
439
440 it.sb = dentry->d_sb;
441 it.buf = __EROFS_BUF_INITIALIZER;
442 erofs_init_metabuf(&it.buf, it.sb);
443 it.dentry = dentry;
444 it.buffer = buffer;
445 it.buffer_size = buffer_size;
446 it.buffer_ofs = 0;
447
448 ret = erofs_xattr_iter_inline(&it, inode, false);
449 if (!ret || ret == -ENOATTR)
450 ret = erofs_xattr_iter_shared(&it, inode, false);
451 if (ret == -ENOATTR)
452 ret = 0;
453 erofs_put_metabuf(&it.buf);
454 return ret ? ret : it.buffer_ofs;
455}
456
457void erofs_xattr_prefixes_cleanup(struct super_block *sb)
458{
459 struct erofs_sb_info *sbi = EROFS_SB(sb);
460 int i;
461
462 if (sbi->xattr_prefixes) {
463 for (i = 0; i < sbi->xattr_prefix_count; i++)
464 kfree(sbi->xattr_prefixes[i].prefix);
465 kfree(sbi->xattr_prefixes);
466 sbi->xattr_prefixes = NULL;
467 }
468}
469
470int erofs_xattr_prefixes_init(struct super_block *sb)
471{
472 struct erofs_sb_info *sbi = EROFS_SB(sb);
473 struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
474 erofs_off_t pos = (erofs_off_t)sbi->xattr_prefix_start << 2;
475 struct erofs_xattr_prefix_item *pfs;
476 int ret = 0, i, len;
477
478 if (!sbi->xattr_prefix_count)
479 return 0;
480
481 pfs = kzalloc(sbi->xattr_prefix_count * sizeof(*pfs), GFP_KERNEL);
482 if (!pfs)
483 return -ENOMEM;
484
485 if (sbi->packed_inode)
486 buf.mapping = sbi->packed_inode->i_mapping;
487 else
488 erofs_init_metabuf(&buf, sb);
489
490 for (i = 0; i < sbi->xattr_prefix_count; i++) {
491 void *ptr = erofs_read_metadata(sb, &buf, &pos, &len);
492
493 if (IS_ERR(ptr)) {
494 ret = PTR_ERR(ptr);
495 break;
496 } else if (len < sizeof(*pfs->prefix) ||
497 len > EROFS_NAME_LEN + sizeof(*pfs->prefix)) {
498 kfree(ptr);
499 ret = -EFSCORRUPTED;
500 break;
501 }
502 pfs[i].prefix = ptr;
503 pfs[i].infix_len = len - sizeof(struct erofs_xattr_long_prefix);
504 }
505
506 erofs_put_metabuf(&buf);
507 sbi->xattr_prefixes = pfs;
508 if (ret)
509 erofs_xattr_prefixes_cleanup(sb);
510 return ret;
511}
512
513#ifdef CONFIG_EROFS_FS_POSIX_ACL
514struct posix_acl *erofs_get_acl(struct inode *inode, int type, bool rcu)
515{
516 struct posix_acl *acl;
517 int prefix, rc;
518 char *value = NULL;
519
520 if (rcu)
521 return ERR_PTR(-ECHILD);
522
523 switch (type) {
524 case ACL_TYPE_ACCESS:
525 prefix = EROFS_XATTR_INDEX_POSIX_ACL_ACCESS;
526 break;
527 case ACL_TYPE_DEFAULT:
528 prefix = EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT;
529 break;
530 default:
531 return ERR_PTR(-EINVAL);
532 }
533
534 rc = erofs_getxattr(inode, prefix, "", NULL, 0);
535 if (rc > 0) {
536 value = kmalloc(rc, GFP_KERNEL);
537 if (!value)
538 return ERR_PTR(-ENOMEM);
539 rc = erofs_getxattr(inode, prefix, "", value, rc);
540 }
541
542 if (rc == -ENOATTR)
543 acl = NULL;
544 else if (rc < 0)
545 acl = ERR_PTR(rc);
546 else
547 acl = posix_acl_from_xattr(&init_user_ns, value, rc);
548 kfree(value);
549 return acl;
550}
551#endif