1 | /* |
2 | * Block driver for Hyper-V VHDX Images |
3 | * |
4 | * Copyright (c) 2013 Red Hat, Inc., |
5 | * |
6 | * Authors: |
7 | * Jeff Cody <jcody@redhat.com> |
8 | * |
9 | * This is based on the "VHDX Format Specification v1.00", published 8/25/2012 |
10 | * by Microsoft: |
11 | * https://www.microsoft.com/en-us/download/details.aspx?id=34750 |
12 | * |
13 | * This file covers the functionality of the metadata log writing, parsing, and |
14 | * replay. |
15 | * |
16 | * This work is licensed under the terms of the GNU LGPL, version 2 or later. |
17 | * See the COPYING.LIB file in the top-level directory. |
18 | * |
19 | */ |
20 | |
21 | #include "qemu/osdep.h" |
22 | #include "qapi/error.h" |
23 | #include "block/block_int.h" |
24 | #include "qemu/error-report.h" |
25 | #include "qemu/bswap.h" |
26 | #include "vhdx.h" |
27 | |
28 | |
29 | typedef struct VHDXLogSequence { |
30 | bool valid; |
31 | uint32_t count; |
32 | VHDXLogEntries log; |
33 | VHDXLogEntryHeader hdr; |
34 | } VHDXLogSequence; |
35 | |
36 | typedef struct VHDXLogDescEntries { |
37 | VHDXLogEntryHeader hdr; |
38 | VHDXLogDescriptor desc[]; |
39 | } VHDXLogDescEntries; |
40 | |
41 | static const MSGUID zero_guid = { 0 }; |
42 | |
43 | /* The log located on the disk is circular buffer containing |
44 | * sectors of 4096 bytes each. |
45 | * |
46 | * It is assumed for the read/write functions below that the |
47 | * circular buffer scheme uses a 'one sector open' to indicate |
48 | * the buffer is full. Given the validation methods used for each |
49 | * sector, this method should be compatible with other methods that |
50 | * do not waste a sector. |
51 | */ |
52 | |
53 | |
54 | /* Allow peeking at the hdr entry at the beginning of the current |
55 | * read index, without advancing the read index */ |
56 | static int vhdx_log_peek_hdr(BlockDriverState *bs, VHDXLogEntries *log, |
57 | VHDXLogEntryHeader *hdr) |
58 | { |
59 | int ret = 0; |
60 | uint64_t offset; |
61 | uint32_t read; |
62 | |
63 | assert(hdr != NULL); |
64 | |
65 | /* peek is only supported on sector boundaries */ |
66 | if (log->read % VHDX_LOG_SECTOR_SIZE) { |
67 | ret = -EFAULT; |
68 | goto exit; |
69 | } |
70 | |
71 | read = log->read; |
72 | /* we are guaranteed that a) log sectors are 4096 bytes, |
73 | * and b) the log length is a multiple of 1MB. So, there |
74 | * is always a round number of sectors in the buffer */ |
75 | if ((read + sizeof(VHDXLogEntryHeader)) > log->length) { |
76 | read = 0; |
77 | } |
78 | |
79 | if (read == log->write) { |
80 | ret = -EINVAL; |
81 | goto exit; |
82 | } |
83 | |
84 | offset = log->offset + read; |
85 | |
86 | ret = bdrv_pread(bs->file, offset, hdr, sizeof(VHDXLogEntryHeader)); |
87 | if (ret < 0) { |
88 | goto exit; |
89 | } |
90 | vhdx_log_entry_hdr_le_import(hdr); |
91 | |
92 | exit: |
93 | return ret; |
94 | } |
95 | |
96 | /* Index increment for log, based on sector boundaries */ |
97 | static int vhdx_log_inc_idx(uint32_t idx, uint64_t length) |
98 | { |
99 | idx += VHDX_LOG_SECTOR_SIZE; |
100 | /* we are guaranteed that a) log sectors are 4096 bytes, |
101 | * and b) the log length is a multiple of 1MB. So, there |
102 | * is always a round number of sectors in the buffer */ |
103 | return idx >= length ? 0 : idx; |
104 | } |
105 | |
106 | |
107 | /* Reset the log to empty */ |
108 | static void vhdx_log_reset(BlockDriverState *bs, BDRVVHDXState *s) |
109 | { |
110 | MSGUID guid = { 0 }; |
111 | s->log.read = s->log.write = 0; |
112 | /* a log guid of 0 indicates an empty log to any parser of v0 |
113 | * VHDX logs */ |
114 | vhdx_update_headers(bs, s, false, &guid); |
115 | } |
116 | |
117 | /* Reads num_sectors from the log (all log sectors are 4096 bytes), |
118 | * into buffer 'buffer'. Upon return, *sectors_read will contain |
119 | * the number of sectors successfully read. |
120 | * |
121 | * It is assumed that 'buffer' is already allocated, and of sufficient |
122 | * size (i.e. >= 4096*num_sectors). |
123 | * |
124 | * If 'peek' is true, then the tail (read) pointer for the circular buffer is |
125 | * not modified. |
126 | * |
127 | * 0 is returned on success, -errno otherwise. */ |
128 | static int vhdx_log_read_sectors(BlockDriverState *bs, VHDXLogEntries *log, |
129 | uint32_t *sectors_read, void *buffer, |
130 | uint32_t num_sectors, bool peek) |
131 | { |
132 | int ret = 0; |
133 | uint64_t offset; |
134 | uint32_t read; |
135 | |
136 | read = log->read; |
137 | |
138 | *sectors_read = 0; |
139 | while (num_sectors) { |
140 | if (read == log->write) { |
141 | /* empty */ |
142 | break; |
143 | } |
144 | offset = log->offset + read; |
145 | |
146 | ret = bdrv_pread(bs->file, offset, buffer, VHDX_LOG_SECTOR_SIZE); |
147 | if (ret < 0) { |
148 | goto exit; |
149 | } |
150 | read = vhdx_log_inc_idx(read, log->length); |
151 | |
152 | *sectors_read = *sectors_read + 1; |
153 | num_sectors--; |
154 | } |
155 | |
156 | exit: |
157 | if (!peek) { |
158 | log->read = read; |
159 | } |
160 | return ret; |
161 | } |
162 | |
163 | /* Writes num_sectors to the log (all log sectors are 4096 bytes), |
164 | * from buffer 'buffer'. Upon return, *sectors_written will contain |
165 | * the number of sectors successfully written. |
166 | * |
167 | * It is assumed that 'buffer' is at least 4096*num_sectors large. |
168 | * |
169 | * 0 is returned on success, -errno otherwise */ |
170 | static int vhdx_log_write_sectors(BlockDriverState *bs, VHDXLogEntries *log, |
171 | uint32_t *sectors_written, void *buffer, |
172 | uint32_t num_sectors) |
173 | { |
174 | int ret = 0; |
175 | uint64_t offset; |
176 | uint32_t write; |
177 | void *buffer_tmp; |
178 | BDRVVHDXState *s = bs->opaque; |
179 | |
180 | ret = vhdx_user_visible_write(bs, s); |
181 | if (ret < 0) { |
182 | goto exit; |
183 | } |
184 | |
185 | write = log->write; |
186 | |
187 | buffer_tmp = buffer; |
188 | while (num_sectors) { |
189 | |
190 | offset = log->offset + write; |
191 | write = vhdx_log_inc_idx(write, log->length); |
192 | if (write == log->read) { |
193 | /* full */ |
194 | break; |
195 | } |
196 | ret = bdrv_pwrite(bs->file, offset, buffer_tmp, |
197 | VHDX_LOG_SECTOR_SIZE); |
198 | if (ret < 0) { |
199 | goto exit; |
200 | } |
201 | buffer_tmp += VHDX_LOG_SECTOR_SIZE; |
202 | |
203 | log->write = write; |
204 | *sectors_written = *sectors_written + 1; |
205 | num_sectors--; |
206 | } |
207 | |
208 | exit: |
209 | return ret; |
210 | } |
211 | |
212 | |
213 | /* Validates a log entry header */ |
214 | static bool vhdx_log_hdr_is_valid(VHDXLogEntries *log, VHDXLogEntryHeader *hdr, |
215 | BDRVVHDXState *s) |
216 | { |
217 | int valid = false; |
218 | |
219 | if (hdr->signature != VHDX_LOG_SIGNATURE) { |
220 | goto exit; |
221 | } |
222 | |
223 | /* if the individual entry length is larger than the whole log |
224 | * buffer, that is obviously invalid */ |
225 | if (log->length < hdr->entry_length) { |
226 | goto exit; |
227 | } |
228 | |
229 | /* length of entire entry must be in units of 4KB (log sector size) */ |
230 | if (hdr->entry_length % (VHDX_LOG_SECTOR_SIZE)) { |
231 | goto exit; |
232 | } |
233 | |
234 | /* per spec, sequence # must be > 0 */ |
235 | if (hdr->sequence_number == 0) { |
236 | goto exit; |
237 | } |
238 | |
239 | /* log entries are only valid if they match the file-wide log guid |
240 | * found in the active header */ |
241 | if (!guid_eq(hdr->log_guid, s->headers[s->curr_header]->log_guid)) { |
242 | goto exit; |
243 | } |
244 | |
245 | if (hdr->descriptor_count * sizeof(VHDXLogDescriptor) > hdr->entry_length) { |
246 | goto exit; |
247 | } |
248 | |
249 | valid = true; |
250 | |
251 | exit: |
252 | return valid; |
253 | } |
254 | |
255 | /* |
256 | * Given a log header, this will validate that the descriptors and the |
257 | * corresponding data sectors (if applicable) |
258 | * |
259 | * Validation consists of: |
260 | * 1. Making sure the sequence numbers matches the entry header |
261 | * 2. Verifying a valid signature ('zero' or 'desc' for descriptors) |
262 | * 3. File offset field is a multiple of 4KB |
263 | * 4. If a data descriptor, the corresponding data sector |
264 | * has its signature ('data') and matching sequence number |
265 | * |
266 | * @desc: the data buffer containing the descriptor |
267 | * @hdr: the log entry header |
268 | * |
269 | * Returns true if valid |
270 | */ |
271 | static bool vhdx_log_desc_is_valid(VHDXLogDescriptor *desc, |
272 | VHDXLogEntryHeader *hdr) |
273 | { |
274 | bool ret = false; |
275 | |
276 | if (desc->sequence_number != hdr->sequence_number) { |
277 | goto exit; |
278 | } |
279 | if (desc->file_offset % VHDX_LOG_SECTOR_SIZE) { |
280 | goto exit; |
281 | } |
282 | |
283 | if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) { |
284 | if (desc->zero_length % VHDX_LOG_SECTOR_SIZE == 0) { |
285 | /* valid */ |
286 | ret = true; |
287 | } |
288 | } else if (desc->signature == VHDX_LOG_DESC_SIGNATURE) { |
289 | /* valid */ |
290 | ret = true; |
291 | } |
292 | |
293 | exit: |
294 | return ret; |
295 | } |
296 | |
297 | |
298 | /* Prior to sector data for a log entry, there is the header |
299 | * and the descriptors referenced in the header: |
300 | * |
301 | * [] = 4KB sector |
302 | * |
303 | * [ hdr, desc ][ desc ][ ... ][ data ][ ... ] |
304 | * |
305 | * The first sector in a log entry has a 64 byte header, and |
306 | * up to 126 32-byte descriptors. If more descriptors than |
307 | * 126 are required, then subsequent sectors can have up to 128 |
308 | * descriptors. Each sector is 4KB. Data follows the descriptor |
309 | * sectors. |
310 | * |
311 | * This will return the number of sectors needed to encompass |
312 | * the passed number of descriptors in desc_cnt. |
313 | * |
314 | * This will never return 0, even if desc_cnt is 0. |
315 | */ |
316 | static int vhdx_compute_desc_sectors(uint32_t desc_cnt) |
317 | { |
318 | uint32_t desc_sectors; |
319 | |
320 | desc_cnt += 2; /* account for header in first sector */ |
321 | desc_sectors = desc_cnt / 128; |
322 | if (desc_cnt % 128) { |
323 | desc_sectors++; |
324 | } |
325 | |
326 | return desc_sectors; |
327 | } |
328 | |
329 | |
330 | /* Reads the log header, and subsequent descriptors (if any). This |
331 | * will allocate all the space for buffer, which must be NULL when |
332 | * passed into this function. Each descriptor will also be validated, |
333 | * and error returned if any are invalid. */ |
334 | static int vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s, |
335 | VHDXLogEntries *log, VHDXLogDescEntries **buffer, |
336 | bool convert_endian) |
337 | { |
338 | int ret = 0; |
339 | uint32_t desc_sectors; |
340 | uint32_t sectors_read; |
341 | VHDXLogEntryHeader hdr; |
342 | VHDXLogDescEntries *desc_entries = NULL; |
343 | VHDXLogDescriptor desc; |
344 | int i; |
345 | |
346 | assert(*buffer == NULL); |
347 | |
348 | ret = vhdx_log_peek_hdr(bs, log, &hdr); |
349 | if (ret < 0) { |
350 | goto exit; |
351 | } |
352 | |
353 | if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) { |
354 | ret = -EINVAL; |
355 | goto exit; |
356 | } |
357 | |
358 | desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count); |
359 | desc_entries = qemu_try_blockalign(bs->file->bs, |
360 | desc_sectors * VHDX_LOG_SECTOR_SIZE); |
361 | if (desc_entries == NULL) { |
362 | ret = -ENOMEM; |
363 | goto exit; |
364 | } |
365 | |
366 | ret = vhdx_log_read_sectors(bs, log, §ors_read, desc_entries, |
367 | desc_sectors, false); |
368 | if (ret < 0) { |
369 | goto free_and_exit; |
370 | } |
371 | if (sectors_read != desc_sectors) { |
372 | ret = -EINVAL; |
373 | goto free_and_exit; |
374 | } |
375 | |
376 | /* put in proper endianness, and validate each desc */ |
377 | for (i = 0; i < hdr.descriptor_count; i++) { |
378 | desc = desc_entries->desc[i]; |
379 | vhdx_log_desc_le_import(&desc); |
380 | if (convert_endian) { |
381 | desc_entries->desc[i] = desc; |
382 | } |
383 | if (vhdx_log_desc_is_valid(&desc, &hdr) == false) { |
384 | ret = -EINVAL; |
385 | goto free_and_exit; |
386 | } |
387 | } |
388 | if (convert_endian) { |
389 | desc_entries->hdr = hdr; |
390 | } |
391 | |
392 | *buffer = desc_entries; |
393 | goto exit; |
394 | |
395 | free_and_exit: |
396 | qemu_vfree(desc_entries); |
397 | exit: |
398 | return ret; |
399 | } |
400 | |
401 | |
402 | /* Flushes the descriptor described by desc to the VHDX image file. |
403 | * If the descriptor is a data descriptor, than 'data' must be non-NULL, |
404 | * and >= 4096 bytes (VHDX_LOG_SECTOR_SIZE), containing the data to be |
405 | * written. |
406 | * |
407 | * Verification is performed to make sure the sequence numbers of a data |
408 | * descriptor match the sequence number in the desc. |
409 | * |
410 | * For a zero descriptor, it may describe multiple sectors to fill with zeroes. |
411 | * In this case, it should be noted that zeroes are written to disk, and the |
412 | * image file is not extended as a sparse file. */ |
413 | static int vhdx_log_flush_desc(BlockDriverState *bs, VHDXLogDescriptor *desc, |
414 | VHDXLogDataSector *data) |
415 | { |
416 | int ret = 0; |
417 | uint64_t seq, file_offset; |
418 | uint32_t offset = 0; |
419 | void *buffer = NULL; |
420 | uint64_t count = 1; |
421 | int i; |
422 | |
423 | buffer = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE); |
424 | |
425 | if (desc->signature == VHDX_LOG_DESC_SIGNATURE) { |
426 | /* data sector */ |
427 | if (data == NULL) { |
428 | ret = -EFAULT; |
429 | goto exit; |
430 | } |
431 | |
432 | /* The sequence number of the data sector must match that |
433 | * in the descriptor */ |
434 | seq = data->sequence_high; |
435 | seq <<= 32; |
436 | seq |= data->sequence_low & 0xffffffff; |
437 | |
438 | if (seq != desc->sequence_number) { |
439 | ret = -EINVAL; |
440 | goto exit; |
441 | } |
442 | |
443 | /* Each data sector is in total 4096 bytes, however the first |
444 | * 8 bytes, and last 4 bytes, are located in the descriptor */ |
445 | memcpy(buffer, &desc->leading_bytes, 8); |
446 | offset += 8; |
447 | |
448 | memcpy(buffer+offset, data->data, 4084); |
449 | offset += 4084; |
450 | |
451 | memcpy(buffer+offset, &desc->trailing_bytes, 4); |
452 | |
453 | } else if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) { |
454 | /* write 'count' sectors of sector */ |
455 | memset(buffer, 0, VHDX_LOG_SECTOR_SIZE); |
456 | count = desc->zero_length / VHDX_LOG_SECTOR_SIZE; |
457 | } else { |
458 | error_report("Invalid VHDX log descriptor entry signature 0x%" PRIx32, |
459 | desc->signature); |
460 | ret = -EINVAL; |
461 | goto exit; |
462 | } |
463 | |
464 | file_offset = desc->file_offset; |
465 | |
466 | /* count is only > 1 if we are writing zeroes */ |
467 | for (i = 0; i < count; i++) { |
468 | ret = bdrv_pwrite_sync(bs->file, file_offset, buffer, |
469 | VHDX_LOG_SECTOR_SIZE); |
470 | if (ret < 0) { |
471 | goto exit; |
472 | } |
473 | file_offset += VHDX_LOG_SECTOR_SIZE; |
474 | } |
475 | |
476 | exit: |
477 | qemu_vfree(buffer); |
478 | return ret; |
479 | } |
480 | |
481 | /* Flush the entire log (as described by 'logs') to the VHDX image |
482 | * file, and then set the log to 'empty' status once complete. |
483 | * |
484 | * The log entries should be validate prior to flushing */ |
485 | static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s, |
486 | VHDXLogSequence *logs) |
487 | { |
488 | int ret = 0; |
489 | int i; |
490 | uint32_t cnt, sectors_read; |
491 | uint64_t new_file_size; |
492 | void *data = NULL; |
493 | int64_t file_length; |
494 | VHDXLogDescEntries *desc_entries = NULL; |
495 | VHDXLogEntryHeader hdr_tmp = { 0 }; |
496 | |
497 | cnt = logs->count; |
498 | |
499 | data = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE); |
500 | |
501 | ret = vhdx_user_visible_write(bs, s); |
502 | if (ret < 0) { |
503 | goto exit; |
504 | } |
505 | |
506 | /* each iteration represents one log sequence, which may span multiple |
507 | * sectors */ |
508 | while (cnt--) { |
509 | ret = vhdx_log_peek_hdr(bs, &logs->log, &hdr_tmp); |
510 | if (ret < 0) { |
511 | goto exit; |
512 | } |
513 | file_length = bdrv_getlength(bs->file->bs); |
514 | if (file_length < 0) { |
515 | ret = file_length; |
516 | goto exit; |
517 | } |
518 | /* if the log shows a FlushedFileOffset larger than our current file |
519 | * size, then that means the file has been truncated / corrupted, and |
520 | * we must refused to open it / use it */ |
521 | if (hdr_tmp.flushed_file_offset > file_length) { |
522 | ret = -EINVAL; |
523 | goto exit; |
524 | } |
525 | |
526 | ret = vhdx_log_read_desc(bs, s, &logs->log, &desc_entries, true); |
527 | if (ret < 0) { |
528 | goto exit; |
529 | } |
530 | |
531 | for (i = 0; i < desc_entries->hdr.descriptor_count; i++) { |
532 | if (desc_entries->desc[i].signature == VHDX_LOG_DESC_SIGNATURE) { |
533 | /* data sector, so read a sector to flush */ |
534 | ret = vhdx_log_read_sectors(bs, &logs->log, §ors_read, |
535 | data, 1, false); |
536 | if (ret < 0) { |
537 | goto exit; |
538 | } |
539 | if (sectors_read != 1) { |
540 | ret = -EINVAL; |
541 | goto exit; |
542 | } |
543 | vhdx_log_data_le_import(data); |
544 | } |
545 | |
546 | ret = vhdx_log_flush_desc(bs, &desc_entries->desc[i], data); |
547 | if (ret < 0) { |
548 | goto exit; |
549 | } |
550 | } |
551 | if (file_length < desc_entries->hdr.last_file_offset) { |
552 | new_file_size = desc_entries->hdr.last_file_offset; |
553 | if (new_file_size % (1 * MiB)) { |
554 | /* round up to nearest 1MB boundary */ |
555 | new_file_size = QEMU_ALIGN_UP(new_file_size, MiB); |
556 | if (new_file_size > INT64_MAX) { |
557 | ret = -EINVAL; |
558 | goto exit; |
559 | } |
560 | ret = bdrv_truncate(bs->file, new_file_size, PREALLOC_MODE_OFF, |
561 | NULL); |
562 | if (ret < 0) { |
563 | goto exit; |
564 | } |
565 | } |
566 | } |
567 | qemu_vfree(desc_entries); |
568 | desc_entries = NULL; |
569 | } |
570 | |
571 | ret = bdrv_flush(bs); |
572 | if (ret < 0) { |
573 | goto exit; |
574 | } |
575 | /* once the log is fully flushed, indicate that we have an empty log |
576 | * now. This also sets the log guid to 0, to indicate an empty log */ |
577 | vhdx_log_reset(bs, s); |
578 | |
579 | exit: |
580 | qemu_vfree(data); |
581 | qemu_vfree(desc_entries); |
582 | return ret; |
583 | } |
584 | |
585 | static int vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s, |
586 | VHDXLogEntries *log, uint64_t seq, |
587 | bool *valid, VHDXLogEntryHeader *entry) |
588 | { |
589 | int ret = 0; |
590 | VHDXLogEntryHeader hdr; |
591 | void *buffer = NULL; |
592 | uint32_t i, desc_sectors, total_sectors, crc; |
593 | uint32_t sectors_read = 0; |
594 | VHDXLogDescEntries *desc_buffer = NULL; |
595 | |
596 | *valid = false; |
597 | |
598 | ret = vhdx_log_peek_hdr(bs, log, &hdr); |
599 | if (ret < 0) { |
600 | goto inc_and_exit; |
601 | } |
602 | |
603 | if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) { |
604 | goto inc_and_exit; |
605 | } |
606 | |
607 | if (seq > 0) { |
608 | if (hdr.sequence_number != seq + 1) { |
609 | goto inc_and_exit; |
610 | } |
611 | } |
612 | |
613 | desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count); |
614 | |
615 | /* Read all log sectors, and calculate log checksum */ |
616 | |
617 | total_sectors = hdr.entry_length / VHDX_LOG_SECTOR_SIZE; |
618 | |
619 | |
620 | /* read_desc() will increment the read idx */ |
621 | ret = vhdx_log_read_desc(bs, s, log, &desc_buffer, false); |
622 | if (ret < 0) { |
623 | goto free_and_exit; |
624 | } |
625 | |
626 | crc = vhdx_checksum_calc(0xffffffff, (void *)desc_buffer, |
627 | desc_sectors * VHDX_LOG_SECTOR_SIZE, 4); |
628 | crc ^= 0xffffffff; |
629 | |
630 | buffer = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE); |
631 | if (total_sectors > desc_sectors) { |
632 | for (i = 0; i < total_sectors - desc_sectors; i++) { |
633 | sectors_read = 0; |
634 | ret = vhdx_log_read_sectors(bs, log, §ors_read, buffer, |
635 | 1, false); |
636 | if (ret < 0 || sectors_read != 1) { |
637 | goto free_and_exit; |
638 | } |
639 | crc = vhdx_checksum_calc(crc, buffer, VHDX_LOG_SECTOR_SIZE, -1); |
640 | crc ^= 0xffffffff; |
641 | } |
642 | } |
643 | crc ^= 0xffffffff; |
644 | if (crc != hdr.checksum) { |
645 | goto free_and_exit; |
646 | } |
647 | |
648 | *valid = true; |
649 | *entry = hdr; |
650 | goto free_and_exit; |
651 | |
652 | inc_and_exit: |
653 | log->read = vhdx_log_inc_idx(log->read, log->length); |
654 | |
655 | free_and_exit: |
656 | qemu_vfree(buffer); |
657 | qemu_vfree(desc_buffer); |
658 | return ret; |
659 | } |
660 | |
661 | /* Search through the log circular buffer, and find the valid, active |
662 | * log sequence, if any exists |
663 | * */ |
664 | static int vhdx_log_search(BlockDriverState *bs, BDRVVHDXState *s, |
665 | VHDXLogSequence *logs) |
666 | { |
667 | int ret = 0; |
668 | uint32_t tail; |
669 | bool seq_valid = false; |
670 | VHDXLogSequence candidate = { 0 }; |
671 | VHDXLogEntryHeader hdr = { 0 }; |
672 | VHDXLogEntries curr_log; |
673 | |
674 | memcpy(&curr_log, &s->log, sizeof(VHDXLogEntries)); |
675 | curr_log.write = curr_log.length; /* assume log is full */ |
676 | curr_log.read = 0; |
677 | |
678 | |
679 | /* now we will go through the whole log sector by sector, until |
680 | * we find a valid, active log sequence, or reach the end of the |
681 | * log buffer */ |
682 | for (;;) { |
683 | uint64_t curr_seq = 0; |
684 | VHDXLogSequence current = { 0 }; |
685 | |
686 | tail = curr_log.read; |
687 | |
688 | ret = vhdx_validate_log_entry(bs, s, &curr_log, curr_seq, |
689 | &seq_valid, &hdr); |
690 | if (ret < 0) { |
691 | goto exit; |
692 | } |
693 | |
694 | if (seq_valid) { |
695 | current.valid = true; |
696 | current.log = curr_log; |
697 | current.log.read = tail; |
698 | current.log.write = curr_log.read; |
699 | current.count = 1; |
700 | current.hdr = hdr; |
701 | |
702 | |
703 | for (;;) { |
704 | ret = vhdx_validate_log_entry(bs, s, &curr_log, curr_seq, |
705 | &seq_valid, &hdr); |
706 | if (ret < 0) { |
707 | goto exit; |
708 | } |
709 | if (seq_valid == false) { |
710 | break; |
711 | } |
712 | current.log.write = curr_log.read; |
713 | current.count++; |
714 | |
715 | curr_seq = hdr.sequence_number; |
716 | } |
717 | } |
718 | |
719 | if (current.valid) { |
720 | if (candidate.valid == false || |
721 | current.hdr.sequence_number > candidate.hdr.sequence_number) { |
722 | candidate = current; |
723 | } |
724 | } |
725 | |
726 | if (curr_log.read < tail) { |
727 | break; |
728 | } |
729 | } |
730 | |
731 | *logs = candidate; |
732 | |
733 | if (candidate.valid) { |
734 | /* this is the next sequence number, for writes */ |
735 | s->log.sequence = candidate.hdr.sequence_number + 1; |
736 | } |
737 | |
738 | |
739 | exit: |
740 | return ret; |
741 | } |
742 | |
743 | /* Parse the replay log. Per the VHDX spec, if the log is present |
744 | * it must be replayed prior to opening the file, even read-only. |
745 | * |
746 | * If read-only, we must replay the log in RAM (or refuse to open |
747 | * a dirty VHDX file read-only) */ |
748 | int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed, |
749 | Error **errp) |
750 | { |
751 | int ret = 0; |
752 | VHDXHeader *hdr; |
753 | VHDXLogSequence logs = { 0 }; |
754 | |
755 | hdr = s->headers[s->curr_header]; |
756 | |
757 | *flushed = false; |
758 | |
759 | /* s->log.hdr is freed in vhdx_close() */ |
760 | if (s->log.hdr == NULL) { |
761 | s->log.hdr = qemu_blockalign(bs, sizeof(VHDXLogEntryHeader)); |
762 | } |
763 | |
764 | s->log.offset = hdr->log_offset; |
765 | s->log.length = hdr->log_length; |
766 | |
767 | if (s->log.offset < VHDX_LOG_MIN_SIZE || |
768 | s->log.offset % VHDX_LOG_MIN_SIZE) { |
769 | ret = -EINVAL; |
770 | goto exit; |
771 | } |
772 | |
773 | /* per spec, only log version of 0 is supported */ |
774 | if (hdr->log_version != 0) { |
775 | ret = -EINVAL; |
776 | goto exit; |
777 | } |
778 | |
779 | /* If either the log guid, or log length is zero, |
780 | * then a replay log is not present */ |
781 | if (guid_eq(hdr->log_guid, zero_guid)) { |
782 | goto exit; |
783 | } |
784 | |
785 | if (hdr->log_length == 0) { |
786 | goto exit; |
787 | } |
788 | |
789 | if (hdr->log_length % VHDX_LOG_MIN_SIZE) { |
790 | ret = -EINVAL; |
791 | goto exit; |
792 | } |
793 | |
794 | |
795 | /* The log is present, we need to find if and where there is an active |
796 | * sequence of valid entries present in the log. */ |
797 | |
798 | ret = vhdx_log_search(bs, s, &logs); |
799 | if (ret < 0) { |
800 | goto exit; |
801 | } |
802 | |
803 | if (logs.valid) { |
804 | if (bs->read_only) { |
805 | bdrv_refresh_filename(bs); |
806 | ret = -EPERM; |
807 | error_setg(errp, |
808 | "VHDX image file '%s' opened read-only, but " |
809 | "contains a log that needs to be replayed" , |
810 | bs->filename); |
811 | error_append_hint(errp, "To replay the log, run:\n" |
812 | "qemu-img check -r all '%s'\n" , |
813 | bs->filename); |
814 | goto exit; |
815 | } |
816 | /* now flush the log */ |
817 | ret = vhdx_log_flush(bs, s, &logs); |
818 | if (ret < 0) { |
819 | goto exit; |
820 | } |
821 | *flushed = true; |
822 | } |
823 | |
824 | |
825 | exit: |
826 | return ret; |
827 | } |
828 | |
829 | |
830 | |
831 | static void vhdx_log_raw_to_le_sector(VHDXLogDescriptor *desc, |
832 | VHDXLogDataSector *sector, void *data, |
833 | uint64_t seq) |
834 | { |
835 | /* 8 + 4084 + 4 = 4096, 1 log sector */ |
836 | memcpy(&desc->leading_bytes, data, 8); |
837 | data += 8; |
838 | desc->leading_bytes = cpu_to_le64(desc->leading_bytes); |
839 | memcpy(sector->data, data, 4084); |
840 | data += 4084; |
841 | memcpy(&desc->trailing_bytes, data, 4); |
842 | desc->trailing_bytes = cpu_to_le32(desc->trailing_bytes); |
843 | data += 4; |
844 | |
845 | sector->sequence_high = (uint32_t) (seq >> 32); |
846 | sector->sequence_low = (uint32_t) (seq & 0xffffffff); |
847 | sector->data_signature = VHDX_LOG_DATA_SIGNATURE; |
848 | |
849 | vhdx_log_desc_le_export(desc); |
850 | vhdx_log_data_le_export(sector); |
851 | } |
852 | |
853 | |
854 | static int vhdx_log_write(BlockDriverState *bs, BDRVVHDXState *s, |
855 | void *data, uint32_t length, uint64_t offset) |
856 | { |
857 | int ret = 0; |
858 | void *buffer = NULL; |
859 | void *merged_sector = NULL; |
860 | void *data_tmp, *sector_write; |
861 | unsigned int i; |
862 | int sector_offset; |
863 | uint32_t desc_sectors, sectors, total_length; |
864 | uint32_t sectors_written = 0; |
865 | uint32_t aligned_length; |
866 | uint32_t leading_length = 0; |
867 | uint32_t trailing_length = 0; |
868 | uint32_t partial_sectors = 0; |
869 | uint32_t bytes_written = 0; |
870 | uint64_t file_offset; |
871 | int64_t file_length; |
872 | VHDXHeader *; |
873 | VHDXLogEntryHeader new_hdr; |
874 | VHDXLogDescriptor *new_desc = NULL; |
875 | VHDXLogDataSector *data_sector = NULL; |
876 | MSGUID new_guid = { 0 }; |
877 | |
878 | header = s->headers[s->curr_header]; |
879 | |
880 | /* need to have offset read data, and be on 4096 byte boundary */ |
881 | |
882 | if (length > header->log_length) { |
883 | /* no log present. we could create a log here instead of failing */ |
884 | ret = -EINVAL; |
885 | goto exit; |
886 | } |
887 | |
888 | if (guid_eq(header->log_guid, zero_guid)) { |
889 | vhdx_guid_generate(&new_guid); |
890 | vhdx_update_headers(bs, s, false, &new_guid); |
891 | } else { |
892 | /* currently, we require that the log be flushed after |
893 | * every write. */ |
894 | ret = -ENOTSUP; |
895 | goto exit; |
896 | } |
897 | |
898 | /* 0 is an invalid sequence number, but may also represent the first |
899 | * log write (or a wrapped seq) */ |
900 | if (s->log.sequence == 0) { |
901 | s->log.sequence = 1; |
902 | } |
903 | |
904 | sector_offset = offset % VHDX_LOG_SECTOR_SIZE; |
905 | file_offset = QEMU_ALIGN_DOWN(offset, VHDX_LOG_SECTOR_SIZE); |
906 | |
907 | aligned_length = length; |
908 | |
909 | /* add in the unaligned head and tail bytes */ |
910 | if (sector_offset) { |
911 | leading_length = (VHDX_LOG_SECTOR_SIZE - sector_offset); |
912 | leading_length = leading_length > length ? length : leading_length; |
913 | aligned_length -= leading_length; |
914 | partial_sectors++; |
915 | } |
916 | |
917 | sectors = aligned_length / VHDX_LOG_SECTOR_SIZE; |
918 | trailing_length = aligned_length - (sectors * VHDX_LOG_SECTOR_SIZE); |
919 | if (trailing_length) { |
920 | partial_sectors++; |
921 | } |
922 | |
923 | sectors += partial_sectors; |
924 | |
925 | file_length = bdrv_getlength(bs->file->bs); |
926 | if (file_length < 0) { |
927 | ret = file_length; |
928 | goto exit; |
929 | } |
930 | |
931 | /* sectors is now how many sectors the data itself takes, not |
932 | * including the header and descriptor metadata */ |
933 | |
934 | new_hdr = (VHDXLogEntryHeader) { |
935 | .signature = VHDX_LOG_SIGNATURE, |
936 | .tail = s->log.tail, |
937 | .sequence_number = s->log.sequence, |
938 | .descriptor_count = sectors, |
939 | .reserved = 0, |
940 | .flushed_file_offset = file_length, |
941 | .last_file_offset = file_length, |
942 | .log_guid = header->log_guid, |
943 | }; |
944 | |
945 | |
946 | desc_sectors = vhdx_compute_desc_sectors(new_hdr.descriptor_count); |
947 | |
948 | total_length = (desc_sectors + sectors) * VHDX_LOG_SECTOR_SIZE; |
949 | new_hdr.entry_length = total_length; |
950 | |
951 | vhdx_log_entry_hdr_le_export(&new_hdr); |
952 | |
953 | buffer = qemu_blockalign(bs, total_length); |
954 | memcpy(buffer, &new_hdr, sizeof(new_hdr)); |
955 | |
956 | new_desc = buffer + sizeof(new_hdr); |
957 | data_sector = buffer + (desc_sectors * VHDX_LOG_SECTOR_SIZE); |
958 | data_tmp = data; |
959 | |
960 | /* All log sectors are 4KB, so for any partial sectors we must |
961 | * merge the data with preexisting data from the final file |
962 | * destination */ |
963 | merged_sector = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE); |
964 | |
965 | for (i = 0; i < sectors; i++) { |
966 | new_desc->signature = VHDX_LOG_DESC_SIGNATURE; |
967 | new_desc->sequence_number = s->log.sequence; |
968 | new_desc->file_offset = file_offset; |
969 | |
970 | if (i == 0 && leading_length) { |
971 | /* partial sector at the front of the buffer */ |
972 | ret = bdrv_pread(bs->file, file_offset, merged_sector, |
973 | VHDX_LOG_SECTOR_SIZE); |
974 | if (ret < 0) { |
975 | goto exit; |
976 | } |
977 | memcpy(merged_sector + sector_offset, data_tmp, leading_length); |
978 | bytes_written = leading_length; |
979 | sector_write = merged_sector; |
980 | } else if (i == sectors - 1 && trailing_length) { |
981 | /* partial sector at the end of the buffer */ |
982 | ret = bdrv_pread(bs->file, |
983 | file_offset, |
984 | merged_sector + trailing_length, |
985 | VHDX_LOG_SECTOR_SIZE - trailing_length); |
986 | if (ret < 0) { |
987 | goto exit; |
988 | } |
989 | memcpy(merged_sector, data_tmp, trailing_length); |
990 | bytes_written = trailing_length; |
991 | sector_write = merged_sector; |
992 | } else { |
993 | bytes_written = VHDX_LOG_SECTOR_SIZE; |
994 | sector_write = data_tmp; |
995 | } |
996 | |
997 | /* populate the raw sector data into the proper structures, |
998 | * as well as update the descriptor, and convert to proper |
999 | * endianness */ |
1000 | vhdx_log_raw_to_le_sector(new_desc, data_sector, sector_write, |
1001 | s->log.sequence); |
1002 | |
1003 | data_tmp += bytes_written; |
1004 | data_sector++; |
1005 | new_desc++; |
1006 | file_offset += VHDX_LOG_SECTOR_SIZE; |
1007 | } |
1008 | |
1009 | /* checksum covers entire entry, from the log header through the |
1010 | * last data sector */ |
1011 | vhdx_update_checksum(buffer, total_length, |
1012 | offsetof(VHDXLogEntryHeader, checksum)); |
1013 | |
1014 | /* now write to the log */ |
1015 | ret = vhdx_log_write_sectors(bs, &s->log, §ors_written, buffer, |
1016 | desc_sectors + sectors); |
1017 | if (ret < 0) { |
1018 | goto exit; |
1019 | } |
1020 | |
1021 | if (sectors_written != desc_sectors + sectors) { |
1022 | /* instead of failing, we could flush the log here */ |
1023 | ret = -EINVAL; |
1024 | goto exit; |
1025 | } |
1026 | |
1027 | s->log.sequence++; |
1028 | /* write new tail */ |
1029 | s->log.tail = s->log.write; |
1030 | |
1031 | exit: |
1032 | qemu_vfree(buffer); |
1033 | qemu_vfree(merged_sector); |
1034 | return ret; |
1035 | } |
1036 | |
1037 | /* Perform a log write, and then immediately flush the entire log */ |
1038 | int vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s, |
1039 | void *data, uint32_t length, uint64_t offset) |
1040 | { |
1041 | int ret = 0; |
1042 | VHDXLogSequence logs = { .valid = true, |
1043 | .count = 1, |
1044 | .hdr = { 0 } }; |
1045 | |
1046 | |
1047 | /* Make sure data written (new and/or changed blocks) is stable |
1048 | * on disk, before creating log entry */ |
1049 | ret = bdrv_flush(bs); |
1050 | if (ret < 0) { |
1051 | goto exit; |
1052 | } |
1053 | |
1054 | ret = vhdx_log_write(bs, s, data, length, offset); |
1055 | if (ret < 0) { |
1056 | goto exit; |
1057 | } |
1058 | logs.log = s->log; |
1059 | |
1060 | /* Make sure log is stable on disk */ |
1061 | ret = bdrv_flush(bs); |
1062 | if (ret < 0) { |
1063 | goto exit; |
1064 | } |
1065 | |
1066 | ret = vhdx_log_flush(bs, s, &logs); |
1067 | if (ret < 0) { |
1068 | goto exit; |
1069 | } |
1070 | |
1071 | s->log = logs.log; |
1072 | |
1073 | exit: |
1074 | return ret; |
1075 | } |
1076 | |
1077 | |