2 * Copyright (C) 2015 The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include <sys/ioctl.h>
22 #include <squashfs_utils.h>
26 #if defined(__linux__)
28 #elif defined(__APPLE__)
30 #define BLKGETSIZE64 DKIOCGETBLOCKCOUNT
31 #define fdatasync(fd) fcntl((fd), F_FULLFSYNC)
34 #include "fec_private.h"
36 /* used by `find_offset'; returns metadata size for a file size `size' and
37 `roots' Reed-Solomon parity bytes */
38 using size_func = uint64_t (*)(uint64_t size, int roots);
40 /* performs a binary search to find a metadata offset from a file so that
41 the metadata size matches function `get_real_size(size, roots)', using
42 the approximate size returned by `get_appr_size' as a starting point */
43 static int find_offset(uint64_t file_size, int roots, uint64_t *offset,
44 size_func get_appr_size, size_func get_real_size)
50 if (file_size % FEC_BLOCKSIZE) {
51 /* must be a multiple of block size */
52 error("file size not multiple of " stringify(FEC_BLOCKSIZE));
57 uint64_t mi = get_appr_size(file_size, roots);
58 uint64_t lo = file_size - mi * 2;
59 uint64_t hi = file_size - mi / 2;
62 mi = ((hi + lo) / (2 * FEC_BLOCKSIZE)) * FEC_BLOCKSIZE;
63 uint64_t total = mi + get_real_size(mi, roots);
65 if (total < file_size) {
66 lo = mi + FEC_BLOCKSIZE;
67 } else if (total > file_size) {
71 debug("file_size = %" PRIu64 " -> offset = %" PRIu64, file_size,
77 warn("could not determine offset");
82 /* returns verity metadata size for a `size' byte file */
83 static uint64_t get_verity_size(uint64_t size, int)
85 return VERITY_METADATA_SIZE + verity_get_size(size, NULL, NULL);
88 /* computes the verity metadata offset for a file with size `f->size' */
89 static int find_verity_offset(fec_handle *f, uint64_t *offset)
94 return find_offset(f->data_size, 0, offset, get_verity_size,
98 /* attempts to read and validate an ecc header from file position `offset' */
99 static int parse_ecc_header(fec_handle *f, uint64_t offset)
102 check(f->ecc.rsn > 0 && f->ecc.rsn < FEC_RSM);
103 check(f->size > sizeof(fec_header));
105 debug("offset = %" PRIu64, offset);
107 if (offset > f->size - sizeof(fec_header)) {
113 /* there's obviously no ecc data at this point, so there is no need to
114 call fec_pread to access this data */
115 if (!raw_pread(f, &header, sizeof(fec_header), offset)) {
116 error("failed to read: %s", strerror(errno));
120 /* move offset back to the beginning of the block for validating header */
121 offset -= offset % FEC_BLOCKSIZE;
123 if (header.magic != FEC_MAGIC) {
126 if (header.version != FEC_VERSION) {
127 error("unsupported ecc version: %u", header.version);
130 if (header.size != sizeof(fec_header)) {
131 error("unexpected ecc header size: %u", header.size);
134 if (header.roots == 0 || header.roots >= FEC_RSM) {
135 error("invalid ecc roots: %u", header.roots);
138 if (f->ecc.roots != (int)header.roots) {
139 error("unexpected number of roots: %d vs %u", f->ecc.roots,
143 if (header.fec_size % header.roots ||
144 header.fec_size % FEC_BLOCKSIZE) {
145 error("inconsistent ecc size %u", header.fec_size);
148 /* structure: data | ecc | header */
149 if (offset < header.fec_size ||
150 offset - header.fec_size != header.inp_size) {
151 error("unexpected input size: %" PRIu64 " vs %" PRIu64, offset,
156 f->data_size = header.inp_size;
157 f->ecc.blocks = fec_div_round_up(f->data_size, FEC_BLOCKSIZE);
158 f->ecc.rounds = fec_div_round_up(f->ecc.blocks, f->ecc.rsn);
160 if (header.fec_size !=
161 (uint32_t)f->ecc.rounds * f->ecc.roots * FEC_BLOCKSIZE) {
162 error("inconsistent ecc size %u", header.fec_size);
166 f->ecc.size = header.fec_size;
167 f->ecc.start = header.inp_size;
169 /* validate encoding data; caller may opt not to use it if invalid */
173 uint8_t buf[FEC_BLOCKSIZE];
175 uint32_t len = FEC_BLOCKSIZE;
177 while (n < f->ecc.size) {
178 if (len > f->ecc.size - n) {
179 len = f->ecc.size - n;
182 if (!raw_pread(f, buf, len, f->ecc.start + n)) {
183 error("failed to read ecc: %s", strerror(errno));
187 SHA256_Update(&ctx, buf, len);
191 uint8_t hash[SHA256_DIGEST_LENGTH];
192 SHA256_Final(hash, &ctx);
194 f->ecc.valid = !memcmp(hash, header.hash, SHA256_DIGEST_LENGTH);
197 warn("ecc data not valid");
203 /* attempts to read an ecc header from `offset', and checks for a backup copy
204 at the end of the block if the primary header is not valid */
205 static int parse_ecc(fec_handle *f, uint64_t offset)
208 check(offset % FEC_BLOCKSIZE == 0);
209 check(offset < UINT64_MAX - FEC_BLOCKSIZE);
211 /* check the primary header at the beginning of the block */
212 if (parse_ecc_header(f, offset) == 0) {
216 /* check the backup header at the end of the block */
217 if (parse_ecc_header(f, offset + FEC_BLOCKSIZE - sizeof(fec_header)) == 0) {
218 warn("using backup ecc header");
225 /* reads the squashfs superblock and returns the size of the file system in
227 static int get_squashfs_size(fec_handle *f, uint64_t *offset)
232 size_t sb_size = squashfs_get_sb_size();
233 check(sb_size <= SSIZE_MAX);
235 uint8_t buffer[sb_size];
237 if (fec_pread(f, buffer, sizeof(buffer), 0) != (ssize_t)sb_size) {
238 error("failed to read superblock: %s", strerror(errno));
244 if (squashfs_parse_sb_buffer(buffer, &sq) < 0) {
245 error("failed to parse superblock: %s", strerror(errno));
249 *offset = sq.bytes_used_4K_padded;
253 /* reads the ext4 superblock and returns the size of the file system in
255 static int get_ext4_size(fec_handle *f, uint64_t *offset)
258 check(f->size > 1024 + sizeof(ext4_super_block));
263 if (fec_pread(f, &sb, sizeof(sb), 1024) != sizeof(sb)) {
264 error("failed to read superblock: %s", strerror(errno));
269 info.len = 0; /* only len is set to 0 to ask the device for real size. */
271 if (ext4_parse_sb(&sb, &info) != 0) {
280 /* attempts to determine file system size, if no fs type is specified in
281 `f->flags', tries all supported types, and returns the size in `offset' */
282 static int get_fs_size(fec_handle *f, uint64_t *offset)
287 if (f->flags & FEC_FS_EXT4) {
288 return get_ext4_size(f, offset);
289 } else if (f->flags & FEC_FS_SQUASH) {
290 return get_squashfs_size(f, offset);
292 /* try all alternatives */
293 int rc = get_ext4_size(f, offset);
296 debug("found ext4fs");
300 rc = get_squashfs_size(f, offset);
303 debug("found squashfs");
310 /* locates, validates, and loads verity metadata from `f->fd' */
311 static int load_verity(fec_handle *f)
314 debug("size = %" PRIu64 ", flags = %d", f->data_size, f->flags);
316 uint64_t offset = f->data_size - VERITY_METADATA_SIZE;
318 /* verity header is at the end of the data area */
319 if (verity_parse_header(f, offset) == 0) {
320 debug("found at %" PRIu64 " (start %" PRIu64 ")", offset,
321 f->verity.hash_start);
325 debug("trying legacy formats");
327 /* legacy format at the end of the partition */
328 if (find_verity_offset(f, &offset) == 0 &&
329 verity_parse_header(f, offset) == 0) {
330 debug("found at %" PRIu64 " (start %" PRIu64 ")", offset,
331 f->verity.hash_start);
335 /* legacy format after the file system, but not at the end */
336 int rc = get_fs_size(f, &offset);
339 debug("file system size = %" PRIu64, offset);
340 rc = verity_parse_header(f, offset);
343 debug("found at %" PRIu64 " (start %" PRIu64 ")", offset,
344 f->verity.hash_start);
351 /* locates, validates, and loads ecc data from `f->fd' */
352 static int load_ecc(fec_handle *f)
355 debug("size = %" PRIu64, f->data_size);
357 uint64_t offset = f->data_size - FEC_BLOCKSIZE;
359 if (parse_ecc(f, offset) == 0) {
360 debug("found at %" PRIu64 " (start %" PRIu64 ")", offset,
368 /* sets `f->size' to the size of the file or block device */
369 static int get_size(fec_handle *f)
375 if (fstat(f->fd, &st) == -1) {
376 error("fstat failed: %s", strerror(errno));
380 if (S_ISBLK(st.st_mode)) {
381 debug("block device");
383 if (ioctl(f->fd, BLKGETSIZE64, &f->size) == -1) {
384 error("ioctl failed: %s", strerror(errno));
387 } else if (S_ISREG(st.st_mode)) {
389 f->size = st.st_size;
391 error("unsupported type %d", (int)st.st_mode);
399 /* clears fec_handle fiels to safe values */
400 static void reset_handle(fec_handle *f)
410 memset(&f->ecc, 0, sizeof(f->ecc));
411 memset(&f->verity, 0, sizeof(f->verity));
414 /* closes and flushes `f->fd' and releases any memory allocated for `f' */
415 int fec_close(struct fec_handle *f)
420 if (f->mode & O_RDWR && fdatasync(f->fd) == -1) {
421 warn("fdatasync failed: %s", strerror(errno));
424 TEMP_FAILURE_RETRY(close(f->fd));
427 if (f->verity.hash) {
428 delete[] f->verity.hash;
430 if (f->verity.salt) {
431 delete[] f->verity.salt;
433 if (f->verity.table) {
434 delete[] f->verity.table;
437 pthread_mutex_destroy(&f->mutex);
445 /* populates `data' from the internal data in `f', returns a value <0 if verity
446 metadata is not available in `f->fd' */
447 int fec_verity_get_metadata(struct fec_handle *f, struct fec_verity_metadata *data)
452 if (!f->verity.metadata_start) {
456 check(f->data_size < f->size);
457 check(f->data_size <= f->verity.hash_start);
458 check(f->data_size <= f->verity.metadata_start);
459 check(f->verity.table);
461 data->disabled = f->verity.disabled;
462 data->data_size = f->data_size;
463 memcpy(data->signature, f->verity.header.signature,
464 sizeof(data->signature));
465 memcpy(data->ecc_signature, f->verity.ecc_header.signature,
466 sizeof(data->ecc_signature));
467 data->table = f->verity.table;
468 data->table_length = f->verity.header.length;
473 /* populates `data' from the internal data in `f', returns a value <0 if ecc
474 metadata is not available in `f->fd' */
475 int fec_ecc_get_metadata(struct fec_handle *f, struct fec_ecc_metadata *data)
484 check(f->data_size < f->size);
485 check(f->ecc.start >= f->data_size);
486 check(f->ecc.start < f->size);
487 check(f->ecc.start % FEC_BLOCKSIZE == 0)
489 data->valid = f->ecc.valid;
490 data->roots = f->ecc.roots;
491 data->blocks = f->ecc.blocks;
492 data->rounds = f->ecc.rounds;
493 data->start = f->ecc.start;
498 /* populates `data' from the internal status in `f' */
499 int fec_get_status(struct fec_handle *f, struct fec_status *s)
506 s->errors = f->errors;
507 s->data_size = f->data_size;
513 /* opens `path' using given options and returns a fec_handle in `handle' if
515 int fec_open(struct fec_handle **handle, const char *path, int mode, int flags,
520 check(roots > 0 && roots < FEC_RSM);
522 debug("path = %s, mode = %d, flags = %d, roots = %d", path, mode, flags,
525 if (mode & (O_CREAT | O_TRUNC | O_EXCL | O_WRONLY)) {
526 /* only reading and updating existing files is supported */
527 error("failed to open '%s': (unsupported mode %d)", path, mode);
532 fec::handle f(new (std::nothrow) fec_handle, fec_close);
535 error("failed to allocate file handle");
540 reset_handle(f.get());
543 f->ecc.roots = roots;
544 f->ecc.rsn = FEC_RSM - roots;
547 if (unlikely(pthread_mutex_init(&f->mutex, NULL) != 0)) {
548 error("failed to create a mutex: %s", strerror(errno));
552 f->fd = TEMP_FAILURE_RETRY(open(path, mode | O_CLOEXEC));
555 error("failed to open '%s': %s", path, strerror(errno));
559 if (get_size(f.get()) == -1) {
560 error("failed to get size for '%s': %s", path, strerror(errno));
564 f->data_size = f->size; /* until ecc and/or verity are loaded */
566 if (load_ecc(f.get()) == -1) {
567 debug("error-correcting codes not found from '%s'", path);
570 if (load_verity(f.get()) == -1) {
571 debug("verity metadata not found from '%s'", path);
574 *handle = f.release();