xattr.c

  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 = -ENODATA;
 76		goto out_unlock;
 77	}
 78
 79	it.buf = __EROFS_BUF_INITIALIZER;
 80	ret = erofs_init_metabuf(&it.buf, sb, erofs_inode_in_metabox(inode));
 81	if (ret)
 82		goto out_unlock;
 83	it.pos = erofs_iloc(inode) + vi->inode_isize;
 84
 85	/* read in shared xattr array (non-atomic, see kmalloc below) */
 86	it.kaddr = erofs_bread(&it.buf, it.pos, true);
 87	if (IS_ERR(it.kaddr)) {
 88		ret = PTR_ERR(it.kaddr);
 89		goto out_unlock;
 90	}
 91
 92	ih = it.kaddr;
 93	vi->xattr_name_filter = le32_to_cpu(ih->h_name_filter);
 94	vi->xattr_shared_count = ih->h_shared_count;
 95	vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
 96						sizeof(uint), GFP_KERNEL);
 97	if (!vi->xattr_shared_xattrs) {
 98		erofs_put_metabuf(&it.buf);
 99		ret = -ENOMEM;
100		goto out_unlock;
101	}
102
103	/* let's skip ibody header */
104	it.pos += sizeof(struct erofs_xattr_ibody_header);
105
106	for (i = 0; i < vi->xattr_shared_count; ++i) {
107		it.kaddr = erofs_bread(&it.buf, it.pos, true);
108		if (IS_ERR(it.kaddr)) {
109			kfree(vi->xattr_shared_xattrs);
110			vi->xattr_shared_xattrs = NULL;
111			ret = PTR_ERR(it.kaddr);
112			goto out_unlock;
113		}
114		vi->xattr_shared_xattrs[i] = le32_to_cpu(*(__le32 *)it.kaddr);
115		it.pos += sizeof(__le32);
116	}
117	erofs_put_metabuf(&it.buf);
118
119	/* paired with smp_mb() at the beginning of the function. */
120	smp_mb();
121	set_bit(EROFS_I_EA_INITED_BIT, &vi->flags);
122
123out_unlock:
124	clear_and_wake_up_bit(EROFS_I_BL_XATTR_BIT, &vi->flags);
125	return ret;
126}
127
128static bool erofs_xattr_user_list(struct dentry *dentry)
129{
130	return test_opt(&EROFS_SB(dentry->d_sb)->opt, XATTR_USER);
131}
132
133static bool erofs_xattr_trusted_list(struct dentry *dentry)
134{
135	return capable(CAP_SYS_ADMIN);
136}
137
138static int erofs_xattr_generic_get(const struct xattr_handler *handler,
139				   struct dentry *unused, struct inode *inode,
140				   const char *name, void *buffer, size_t size)
141{
142	if (handler->flags == EROFS_XATTR_INDEX_USER &&
143	    !test_opt(&EROFS_I_SB(inode)->opt, XATTR_USER))
144		return -EOPNOTSUPP;
145
146	return erofs_getxattr(inode, handler->flags, name, buffer, size);
147}
148
149const struct xattr_handler erofs_xattr_user_handler = {
150	.prefix	= XATTR_USER_PREFIX,
151	.flags	= EROFS_XATTR_INDEX_USER,
152	.list	= erofs_xattr_user_list,
153	.get	= erofs_xattr_generic_get,
154};
155
156const struct xattr_handler erofs_xattr_trusted_handler = {
157	.prefix	= XATTR_TRUSTED_PREFIX,
158	.flags	= EROFS_XATTR_INDEX_TRUSTED,
159	.list	= erofs_xattr_trusted_list,
160	.get	= erofs_xattr_generic_get,
161};
162
163#ifdef CONFIG_EROFS_FS_SECURITY
164const struct xattr_handler __maybe_unused erofs_xattr_security_handler = {
165	.prefix	= XATTR_SECURITY_PREFIX,
166	.flags	= EROFS_XATTR_INDEX_SECURITY,
167	.get	= erofs_xattr_generic_get,
168};
169#endif
170
171const struct xattr_handler * const erofs_xattr_handlers[] = {
172	&erofs_xattr_user_handler,
173	&erofs_xattr_trusted_handler,
174#ifdef CONFIG_EROFS_FS_SECURITY
175	&erofs_xattr_security_handler,
176#endif
177	NULL,
178};
179
180static int erofs_xattr_copy_to_buffer(struct erofs_xattr_iter *it,
181				      unsigned int len)
182{
183	unsigned int slice, processed;
184	struct super_block *sb = it->sb;
185	void *src;
186
187	for (processed = 0; processed < len; processed += slice) {
188		it->kaddr = erofs_bread(&it->buf, it->pos, true);
189		if (IS_ERR(it->kaddr))
190			return PTR_ERR(it->kaddr);
191
192		src = it->kaddr;
193		slice = min_t(unsigned int, sb->s_blocksize -
194				erofs_blkoff(sb, it->pos), len - processed);
195		memcpy(it->buffer + it->buffer_ofs, src, slice);
196		it->buffer_ofs += slice;
197		it->pos += slice;
198	}
199	return 0;
200}
201
202static int erofs_listxattr_foreach(struct erofs_xattr_iter *it)
203{
204	struct erofs_xattr_entry entry;
205	unsigned int base_index, name_total, prefix_len, infix_len = 0;
206	const char *prefix, *infix = NULL;
207	int err;
208
209	/* 1. handle xattr entry */
210	entry = *(struct erofs_xattr_entry *)it->kaddr;
211	it->pos += sizeof(struct erofs_xattr_entry);
212
213	base_index = entry.e_name_index;
214	if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
215		struct erofs_sb_info *sbi = EROFS_SB(it->sb);
216		struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
217			(entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
218
219		if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
220			return 0;
221		infix = pf->prefix->infix;
222		infix_len = pf->infix_len;
223		base_index = pf->prefix->base_index;
224	}
225
226	prefix = erofs_xattr_prefix(base_index, it->dentry);
227	if (!prefix)
228		return 0;
229	prefix_len = strlen(prefix);
230	name_total = prefix_len + infix_len + entry.e_name_len + 1;
231
232	if (!it->buffer) {
233		it->buffer_ofs += name_total;
234		return 0;
235	}
236
237	if (it->buffer_ofs + name_total > it->buffer_size)
238		return -ERANGE;
239
240	memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len);
241	memcpy(it->buffer + it->buffer_ofs + prefix_len, infix, infix_len);
242	it->buffer_ofs += prefix_len + infix_len;
243
244	/* 2. handle xattr name */
245	err = erofs_xattr_copy_to_buffer(it, entry.e_name_len);
246	if (err)
247		return err;
248
249	it->buffer[it->buffer_ofs++] = '\0';
250	return 0;
251}
252
253static int erofs_getxattr_foreach(struct erofs_xattr_iter *it)
254{
255	struct super_block *sb = it->sb;
256	struct erofs_xattr_entry entry;
257	unsigned int slice, processed, value_sz;
258
259	/* 1. handle xattr entry */
260	entry = *(struct erofs_xattr_entry *)it->kaddr;
261	it->pos += sizeof(struct erofs_xattr_entry);
262	value_sz = le16_to_cpu(entry.e_value_size);
263
264	/* should also match the infix for long name prefixes */
265	if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
266		struct erofs_sb_info *sbi = EROFS_SB(sb);
267		struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
268			(entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
269
270		if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
271			return -ENODATA;
272
273		if (it->index != pf->prefix->base_index ||
274		    it->name.len != entry.e_name_len + pf->infix_len)
275			return -ENODATA;
276
277		if (memcmp(it->name.name, pf->prefix->infix, pf->infix_len))
278			return -ENODATA;
279
280		it->infix_len = pf->infix_len;
281	} else {
282		if (it->index != entry.e_name_index ||
283		    it->name.len != entry.e_name_len)
284			return -ENODATA;
285
286		it->infix_len = 0;
287	}
288
289	/* 2. handle xattr name */
290	for (processed = 0; processed < entry.e_name_len; processed += slice) {
291		it->kaddr = erofs_bread(&it->buf, it->pos, true);
292		if (IS_ERR(it->kaddr))
293			return PTR_ERR(it->kaddr);
294
295		slice = min_t(unsigned int,
296				sb->s_blocksize - erofs_blkoff(sb, it->pos),
297				entry.e_name_len - processed);
298		if (memcmp(it->name.name + it->infix_len + processed,
299			   it->kaddr, slice))
300			return -ENODATA;
301		it->pos += slice;
302	}
303
304	/* 3. handle xattr value */
305	if (!it->buffer) {
306		it->buffer_ofs = value_sz;
307		return 0;
308	}
309
310	if (it->buffer_size < value_sz)
311		return -ERANGE;
312
313	return erofs_xattr_copy_to_buffer(it, value_sz);
314}
315
316static int erofs_xattr_iter_inline(struct erofs_xattr_iter *it,
317				   struct inode *inode, bool getxattr)
318{
319	struct erofs_inode *const vi = EROFS_I(inode);
320	unsigned int xattr_header_sz, remaining, entry_sz;
321	erofs_off_t next_pos;
322	int ret;
323
324	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
325			  sizeof(u32) * vi->xattr_shared_count;
326	if (xattr_header_sz >= vi->xattr_isize) {
327		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
328		return -ENODATA;
329	}
330
331	ret = erofs_init_metabuf(&it->buf, it->sb, erofs_inode_in_metabox(inode));
332	if (ret)
333		return ret;
334	remaining = vi->xattr_isize - xattr_header_sz;
335	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
336
337	while (remaining) {
338		it->kaddr = erofs_bread(&it->buf, it->pos, true);
339		if (IS_ERR(it->kaddr))
340			return PTR_ERR(it->kaddr);
341
342		entry_sz = erofs_xattr_entry_size(it->kaddr);
343		/* xattr on-disk corruption: xattr entry beyond xattr_isize */
344		if (remaining < entry_sz) {
345			DBG_BUGON(1);
346			return -EFSCORRUPTED;
347		}
348		remaining -= entry_sz;
349		next_pos = it->pos + entry_sz;
350
351		if (getxattr)
352			ret = erofs_getxattr_foreach(it);
353		else
354			ret = erofs_listxattr_foreach(it);
355		if ((getxattr && ret != -ENODATA) || (!getxattr && ret))
356			break;
357
358		it->pos = next_pos;
359	}
360	return ret;
361}
362
363static int erofs_xattr_iter_shared(struct erofs_xattr_iter *it,
364				   struct inode *inode, bool getxattr)
365{
366	struct erofs_inode *const vi = EROFS_I(inode);
367	struct super_block *const sb = it->sb;
368	struct erofs_sb_info *sbi = EROFS_SB(sb);
369	unsigned int i = 0;
370	int ret;
371
372	ret = erofs_init_metabuf(&it->buf, sb,
373				 erofs_sb_has_shared_ea_in_metabox(sbi));
374	if (ret)
375		return ret;
376
377	while (i < vi->xattr_shared_count) {
378		it->pos = erofs_pos(sb, sbi->xattr_blkaddr) +
379				vi->xattr_shared_xattrs[i++] * sizeof(__le32);
380		it->kaddr = erofs_bread(&it->buf, it->pos, true);
381		if (IS_ERR(it->kaddr))
382			return PTR_ERR(it->kaddr);
383
384		if (getxattr)
385			ret = erofs_getxattr_foreach(it);
386		else
387			ret = erofs_listxattr_foreach(it);
388		if ((getxattr && ret != -ENODATA) || (!getxattr && ret))
389			break;
390	}
391	return i ? ret : -ENODATA;
392}
393
394int erofs_getxattr(struct inode *inode, int index, const char *name,
395		   void *buffer, size_t buffer_size)
396{
397	int ret;
398	unsigned int hashbit;
399	struct erofs_xattr_iter it;
400	struct erofs_inode *vi = EROFS_I(inode);
401	struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
402
403	if (!name)
404		return -EINVAL;
405
406	ret = erofs_init_inode_xattrs(inode);
407	if (ret)
408		return ret;
409
410	/* reserved flag is non-zero if there's any change of on-disk format */
411	if (erofs_sb_has_xattr_filter(sbi) && !sbi->xattr_filter_reserved) {
412		hashbit = xxh32(name, strlen(name),
413				EROFS_XATTR_FILTER_SEED + index);
414		hashbit &= EROFS_XATTR_FILTER_BITS - 1;
415		if (vi->xattr_name_filter & (1U << hashbit))
416			return -ENODATA;
417	}
418
419	it.index = index;
420	it.name = QSTR(name);
421	if (it.name.len > EROFS_NAME_LEN)
422		return -ERANGE;
423
424	it.sb = inode->i_sb;
425	it.buf = __EROFS_BUF_INITIALIZER;
426	it.buffer = buffer;
427	it.buffer_size = buffer_size;
428	it.buffer_ofs = 0;
429
430	ret = erofs_xattr_iter_inline(&it, inode, true);
431	if (ret == -ENODATA)
432		ret = erofs_xattr_iter_shared(&it, inode, true);
433	erofs_put_metabuf(&it.buf);
434	return ret ? ret : it.buffer_ofs;
435}
436
437ssize_t erofs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
438{
439	int ret;
440	struct erofs_xattr_iter it;
441	struct inode *inode = d_inode(dentry);
442
443	ret = erofs_init_inode_xattrs(inode);
444	if (ret == -ENODATA)
445		return 0;
446	if (ret)
447		return ret;
448
449	it.sb = dentry->d_sb;
450	it.buf = __EROFS_BUF_INITIALIZER;
451	it.dentry = dentry;
452	it.buffer = buffer;
453	it.buffer_size = buffer_size;
454	it.buffer_ofs = 0;
455
456	ret = erofs_xattr_iter_inline(&it, inode, false);
457	if (!ret || ret == -ENODATA)
458		ret = erofs_xattr_iter_shared(&it, inode, false);
459	if (ret == -ENODATA)
460		ret = 0;
461	erofs_put_metabuf(&it.buf);
462	return ret ? ret : it.buffer_ofs;
463}
464
465void erofs_xattr_prefixes_cleanup(struct super_block *sb)
466{
467	struct erofs_sb_info *sbi = EROFS_SB(sb);
468	int i;
469
470	if (sbi->xattr_prefixes) {
471		for (i = 0; i < sbi->xattr_prefix_count; i++)
472			kfree(sbi->xattr_prefixes[i].prefix);
473		kfree(sbi->xattr_prefixes);
474		sbi->xattr_prefixes = NULL;
475	}
476}
477
478int erofs_xattr_prefixes_init(struct super_block *sb)
479{
480	struct erofs_sb_info *sbi = EROFS_SB(sb);
481	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
482	erofs_off_t pos = (erofs_off_t)sbi->xattr_prefix_start << 2;
483	struct erofs_xattr_prefix_item *pfs;
484	int ret = 0, i, len;
485	bool plain = erofs_sb_has_plain_xattr_pfx(sbi);
486
487	if (!sbi->xattr_prefix_count)
488		return 0;
489
490	pfs = kcalloc(sbi->xattr_prefix_count, sizeof(*pfs), GFP_KERNEL);
491	if (!pfs)
492		return -ENOMEM;
493
494	if (!plain) {
495		if (erofs_sb_has_metabox(sbi))
496			(void)erofs_init_metabuf(&buf, sb, true);
497		else if (sbi->packed_inode)
498			buf.mapping = sbi->packed_inode->i_mapping;
499		else
500			plain = true;
501	}
502	if (plain)
503		(void)erofs_init_metabuf(&buf, sb, false);
504
505	for (i = 0; i < sbi->xattr_prefix_count; i++) {
506		void *ptr = erofs_read_metadata(sb, &buf, &pos, &len);
507
508		if (IS_ERR(ptr)) {
509			ret = PTR_ERR(ptr);
510			break;
511		} else if (len < sizeof(*pfs->prefix) ||
512			   len > EROFS_NAME_LEN + sizeof(*pfs->prefix)) {
513			kfree(ptr);
514			ret = -EFSCORRUPTED;
515			break;
516		}
517		pfs[i].prefix = ptr;
518		pfs[i].infix_len = len - sizeof(struct erofs_xattr_long_prefix);
519	}
520
521	erofs_put_metabuf(&buf);
522	sbi->xattr_prefixes = pfs;
523	if (ret)
524		erofs_xattr_prefixes_cleanup(sb);
525	return ret;
526}
527
528#ifdef CONFIG_EROFS_FS_POSIX_ACL
529struct posix_acl *erofs_get_acl(struct inode *inode, int type, bool rcu)
530{
531	struct posix_acl *acl;
532	int prefix, rc;
533	char *value = NULL;
534
535	if (rcu)
536		return ERR_PTR(-ECHILD);
537
538	switch (type) {
539	case ACL_TYPE_ACCESS:
540		prefix = EROFS_XATTR_INDEX_POSIX_ACL_ACCESS;
541		break;
542	case ACL_TYPE_DEFAULT:
543		prefix = EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT;
544		break;
545	default:
546		return ERR_PTR(-EINVAL);
547	}
548
549	rc = erofs_getxattr(inode, prefix, "", NULL, 0);
550	if (rc > 0) {
551		value = kmalloc(rc, GFP_KERNEL);
552		if (!value)
553			return ERR_PTR(-ENOMEM);
554		rc = erofs_getxattr(inode, prefix, "", value, rc);
555	}
556
557	if (rc == -ENODATA)
558		acl = NULL;
559	else if (rc < 0)
560		acl = ERR_PTR(rc);
561	else
562		acl = posix_acl_from_xattr(&init_user_ns, value, rc);
563	kfree(value);
564	return acl;
565}
566#endif