fs_mgr_verity.cpp revision cab56c0ba53bf702a7df10eb39755af0b5525088 
1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
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
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17#include <ctype.h>
18#include <errno.h>
19#include <fcntl.h>
20#include <inttypes.h>
21#include <libgen.h>
22#include <stdio.h>
23#include <stdlib.h>
24#include <string.h>
25#include <sys/mount.h>
26#include <sys/stat.h>
27#include <sys/types.h>
28#include <sys/wait.h>
29#include <time.h>
30#include <unistd.h>
31
32#include <android-base/file.h>
33#include <android-base/properties.h>
34#include <android-base/strings.h>
35#include <android-base/unique_fd.h>
36#include <crypto_utils/android_pubkey.h>
37#include <cutils/properties.h>
38#include <logwrap/logwrap.h>
39#include <openssl/obj_mac.h>
40#include <openssl/rsa.h>
41#include <openssl/sha.h>
42
43#include "fec/io.h"
44
45#include "fs_mgr.h"
46#include "fs_mgr_priv.h"
47#include "fs_mgr_priv_dm_ioctl.h"
48
49#define VERITY_TABLE_RSA_KEY "/verity_key"
50#define VERITY_TABLE_HASH_IDX 8
51#define VERITY_TABLE_SALT_IDX 9
52
53#define VERITY_TABLE_OPT_RESTART "restart_on_corruption"
54#define VERITY_TABLE_OPT_LOGGING "ignore_corruption"
55#define VERITY_TABLE_OPT_IGNZERO "ignore_zero_blocks"
56
57#define VERITY_TABLE_OPT_FEC_FORMAT \
58    "use_fec_from_device %s fec_start %" PRIu64 " fec_blocks %" PRIu64 \
59    " fec_roots %u " VERITY_TABLE_OPT_IGNZERO
60#define VERITY_TABLE_OPT_FEC_ARGS 9
61
62#define METADATA_MAGIC 0x01564c54
63#define METADATA_TAG_MAX_LENGTH 63
64#define METADATA_EOD "eod"
65
66#define VERITY_LASTSIG_TAG "verity_lastsig"
67
68#define VERITY_STATE_TAG "verity_state"
69#define VERITY_STATE_HEADER 0x83c0ae9d
70#define VERITY_STATE_VERSION 1
71
72#define VERITY_KMSG_RESTART "dm-verity device corrupted"
73#define VERITY_KMSG_BUFSIZE 1024
74
75#define READ_BUF_SIZE 4096
76
77#define __STRINGIFY(x) #x
78#define STRINGIFY(x) __STRINGIFY(x)
79
80struct verity_state {
81    uint32_t header;
82    uint32_t version;
83    int32_t mode;
84};
85
86extern struct fs_info info;
87
88static RSA *load_key(const char *path)
89{
90    uint8_t key_data[ANDROID_PUBKEY_ENCODED_SIZE];
91
92    FILE* f = fopen(path, "r");
93    if (!f) {
94        LERROR << "Can't open " << path;
95        return NULL;
96    }
97
98    if (!fread(key_data, sizeof(key_data), 1, f)) {
99        LERROR << "Could not read key!";
100        fclose(f);
101        return NULL;
102    }
103
104    fclose(f);
105
106    RSA* key = NULL;
107    if (!android_pubkey_decode(key_data, sizeof(key_data), &key)) {
108        LERROR << "Could not parse key!";
109        return NULL;
110    }
111
112    return key;
113}
114
115static int verify_table(const uint8_t *signature, size_t signature_size,
116        const char *table, uint32_t table_length)
117{
118    RSA *key;
119    uint8_t hash_buf[SHA256_DIGEST_LENGTH];
120    int retval = -1;
121
122    // Hash the table
123    SHA256((uint8_t*)table, table_length, hash_buf);
124
125    // Now get the public key from the keyfile
126    key = load_key(VERITY_TABLE_RSA_KEY);
127    if (!key) {
128        LERROR << "Couldn't load verity keys";
129        goto out;
130    }
131
132    // verify the result
133    if (!RSA_verify(NID_sha256, hash_buf, sizeof(hash_buf), signature,
134                    signature_size, key)) {
135        LERROR << "Couldn't verify table";
136        goto out;
137    }
138
139    retval = 0;
140
141out:
142    RSA_free(key);
143    return retval;
144}
145
146static int verify_verity_signature(const struct fec_verity_metadata& verity)
147{
148    if (verify_table(verity.signature, sizeof(verity.signature),
149            verity.table, verity.table_length) == 0 ||
150        verify_table(verity.ecc_signature, sizeof(verity.ecc_signature),
151            verity.table, verity.table_length) == 0) {
152        return 0;
153    }
154
155    return -1;
156}
157
158static int invalidate_table(char *table, size_t table_length)
159{
160    size_t n = 0;
161    size_t idx = 0;
162    size_t cleared = 0;
163
164    while (n < table_length) {
165        if (table[n++] == ' ') {
166            ++idx;
167        }
168
169        if (idx != VERITY_TABLE_HASH_IDX && idx != VERITY_TABLE_SALT_IDX) {
170            continue;
171        }
172
173        while (n < table_length && table[n] != ' ') {
174            table[n++] = '0';
175        }
176
177        if (++cleared == 2) {
178            return 0;
179        }
180    }
181
182    return -1;
183}
184
185struct verity_table_params {
186    char *table;
187    int mode;
188    struct fec_ecc_metadata ecc;
189    const char *ecc_dev;
190};
191
192typedef bool (*format_verity_table_func)(char *buf, const size_t bufsize,
193        const struct verity_table_params *params);
194
195static bool format_verity_table(char *buf, const size_t bufsize,
196        const struct verity_table_params *params)
197{
198    const char *mode_flag = NULL;
199    int res = -1;
200
201    if (params->mode == VERITY_MODE_RESTART) {
202        mode_flag = VERITY_TABLE_OPT_RESTART;
203    } else if (params->mode == VERITY_MODE_LOGGING) {
204        mode_flag = VERITY_TABLE_OPT_LOGGING;
205    }
206
207    if (params->ecc.valid) {
208        if (mode_flag) {
209            res = snprintf(buf, bufsize,
210                    "%s %u %s " VERITY_TABLE_OPT_FEC_FORMAT,
211                    params->table, 1 + VERITY_TABLE_OPT_FEC_ARGS, mode_flag, params->ecc_dev,
212                    params->ecc.start / FEC_BLOCKSIZE, params->ecc.blocks, params->ecc.roots);
213        } else {
214            res = snprintf(buf, bufsize,
215                    "%s %u " VERITY_TABLE_OPT_FEC_FORMAT,
216                    params->table, VERITY_TABLE_OPT_FEC_ARGS, params->ecc_dev,
217                    params->ecc.start / FEC_BLOCKSIZE, params->ecc.blocks, params->ecc.roots);
218        }
219    } else if (mode_flag) {
220        res = snprintf(buf, bufsize, "%s 2 " VERITY_TABLE_OPT_IGNZERO " %s", params->table,
221                    mode_flag);
222    } else {
223        res = snprintf(buf, bufsize, "%s 1 " VERITY_TABLE_OPT_IGNZERO, params->table);
224    }
225
226    if (res < 0 || (size_t)res >= bufsize) {
227        LERROR << "Error building verity table; insufficient buffer size?";
228        return false;
229    }
230
231    return true;
232}
233
234static bool format_legacy_verity_table(char *buf, const size_t bufsize,
235        const struct verity_table_params *params)
236{
237    int res;
238
239    if (params->mode == VERITY_MODE_EIO) {
240        res = strlcpy(buf, params->table, bufsize);
241    } else {
242        res = snprintf(buf, bufsize, "%s %d", params->table, params->mode);
243    }
244
245    if (res < 0 || (size_t)res >= bufsize) {
246        LERROR << "Error building verity table; insufficient buffer size?";
247        return false;
248    }
249
250    return true;
251}
252
253static int load_verity_table(struct dm_ioctl *io, const std::string &name,
254                             uint64_t device_size, int fd,
255        const struct verity_table_params *params, format_verity_table_func format)
256{
257    char *verity_params;
258    char *buffer = (char*) io;
259    size_t bufsize;
260
261    fs_mgr_verity_ioctl_init(io, name, DM_STATUS_TABLE_FLAG);
262
263    struct dm_target_spec *tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)];
264
265    // set tgt arguments
266    io->target_count = 1;
267    tgt->status = 0;
268    tgt->sector_start = 0;
269    tgt->length = device_size / 512;
270    strcpy(tgt->target_type, "verity");
271
272    // build the verity params
273    verity_params = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec);
274    bufsize = DM_BUF_SIZE - (verity_params - buffer);
275
276    if (!format(verity_params, bufsize, params)) {
277        LERROR << "Failed to format verity parameters";
278        return -1;
279    }
280
281    LINFO << "loading verity table: '" << verity_params << "'";
282
283    // set next target boundary
284    verity_params += strlen(verity_params) + 1;
285    verity_params = (char*)(((uintptr_t)verity_params + 7) & ~7);
286    tgt->next = verity_params - buffer;
287
288    // send the ioctl to load the verity table
289    if (ioctl(fd, DM_TABLE_LOAD, io)) {
290        PERROR << "Error loading verity table";
291        return -1;
292    }
293
294    return 0;
295}
296
297static int check_verity_restart(const char *fname)
298{
299    char buffer[VERITY_KMSG_BUFSIZE + 1];
300    int fd;
301    int rc = 0;
302    ssize_t size;
303    struct stat s;
304
305    fd = TEMP_FAILURE_RETRY(open(fname, O_RDONLY | O_CLOEXEC));
306
307    if (fd == -1) {
308        if (errno != ENOENT) {
309            PERROR << "Failed to open " << fname;
310        }
311        goto out;
312    }
313
314    if (fstat(fd, &s) == -1) {
315        PERROR << "Failed to fstat " << fname;
316        goto out;
317    }
318
319    size = VERITY_KMSG_BUFSIZE;
320
321    if (size > s.st_size) {
322        size = s.st_size;
323    }
324
325    if (lseek(fd, s.st_size - size, SEEK_SET) == -1) {
326        PERROR << "Failed to lseek " << (intmax_t)(s.st_size - size) << " " << fname;
327        goto out;
328    }
329
330    if (!android::base::ReadFully(fd, buffer, size)) {
331        PERROR << "Failed to read " << size << " bytes from " << fname;
332        goto out;
333    }
334
335    buffer[size] = '\0';
336
337    if (strstr(buffer, VERITY_KMSG_RESTART) != NULL) {
338        rc = 1;
339    }
340
341out:
342    if (fd != -1) {
343        close(fd);
344    }
345
346    return rc;
347}
348
349static int was_verity_restart()
350{
351    static const char* files[] = {
352        // clang-format off
353        "/sys/fs/pstore/console-ramoops-0",
354        "/sys/fs/pstore/console-ramoops",
355        "/proc/last_kmsg",
356        NULL
357        // clang-format on
358    };
359    int i;
360
361    for (i = 0; files[i]; ++i) {
362        if (check_verity_restart(files[i])) {
363            return 1;
364        }
365    }
366
367    return 0;
368}
369
370static int metadata_add(FILE *fp, long start, const char *tag,
371        unsigned int length, off64_t *offset)
372{
373    if (fseek(fp, start, SEEK_SET) < 0 ||
374        fprintf(fp, "%s %u\n", tag, length) < 0) {
375        return -1;
376    }
377
378    *offset = ftell(fp);
379
380    if (fseek(fp, length, SEEK_CUR) < 0 ||
381        fprintf(fp, METADATA_EOD " 0\n") < 0) {
382        return -1;
383    }
384
385    return 0;
386}
387
388static int metadata_find(const char *fname, const char *stag,
389        unsigned int slength, off64_t *offset)
390{
391    FILE *fp = NULL;
392    char tag[METADATA_TAG_MAX_LENGTH + 1];
393    int rc = -1;
394    int n;
395    long start = 0x4000; /* skip cryptfs metadata area */
396    uint32_t magic;
397    unsigned int length = 0;
398
399    if (!fname) {
400        return -1;
401    }
402
403    fp = fopen(fname, "r+");
404
405    if (!fp) {
406        PERROR << "Failed to open " << fname;
407        goto out;
408    }
409
410    /* check magic */
411    if (fseek(fp, start, SEEK_SET) < 0 ||
412        fread(&magic, sizeof(magic), 1, fp) != 1) {
413        PERROR << "Failed to read magic from " << fname;
414        goto out;
415    }
416
417    if (magic != METADATA_MAGIC) {
418        magic = METADATA_MAGIC;
419
420        if (fseek(fp, start, SEEK_SET) < 0 ||
421            fwrite(&magic, sizeof(magic), 1, fp) != 1) {
422            PERROR << "Failed to write magic to " << fname;
423            goto out;
424        }
425
426        rc = metadata_add(fp, start + sizeof(magic), stag, slength, offset);
427        if (rc < 0) {
428            PERROR << "Failed to add metadata to " << fname;
429        }
430
431        goto out;
432    }
433
434    start += sizeof(magic);
435
436    while (1) {
437        n = fscanf(fp, "%" STRINGIFY(METADATA_TAG_MAX_LENGTH) "s %u\n",
438                tag, &length);
439
440        if (n == 2 && strcmp(tag, METADATA_EOD)) {
441            /* found a tag */
442            start = ftell(fp);
443
444            if (!strcmp(tag, stag) && length == slength) {
445                *offset = start;
446                rc = 0;
447                goto out;
448            }
449
450            start += length;
451
452            if (fseek(fp, length, SEEK_CUR) < 0) {
453                PERROR << "Failed to seek " << fname;
454                goto out;
455            }
456        } else {
457            rc = metadata_add(fp, start, stag, slength, offset);
458            if (rc < 0) {
459                PERROR << "Failed to write metadata to " << fname;
460            }
461            goto out;
462        }
463   }
464
465out:
466    if (fp) {
467        fflush(fp);
468        fclose(fp);
469    }
470
471    return rc;
472}
473
474static int write_verity_state(const char *fname, off64_t offset, int32_t mode)
475{
476    int fd;
477    int rc = -1;
478    struct verity_state s = { VERITY_STATE_HEADER, VERITY_STATE_VERSION, mode };
479
480    fd = TEMP_FAILURE_RETRY(open(fname, O_WRONLY | O_SYNC | O_CLOEXEC));
481
482    if (fd == -1) {
483        PERROR << "Failed to open " << fname;
484        goto out;
485    }
486
487    if (TEMP_FAILURE_RETRY(pwrite64(fd, &s, sizeof(s), offset)) != sizeof(s)) {
488        PERROR << "Failed to write " << sizeof(s) << " bytes to " << fname
489               << " to offset " << offset;
490        goto out;
491    }
492
493    rc = 0;
494
495out:
496    if (fd != -1) {
497        close(fd);
498    }
499
500    return rc;
501}
502
503static int read_verity_state(const char *fname, off64_t offset, int *mode)
504{
505    int fd = -1;
506    int rc = -1;
507    struct verity_state s;
508
509    fd = TEMP_FAILURE_RETRY(open(fname, O_RDONLY | O_CLOEXEC));
510
511    if (fd == -1) {
512        PERROR << "Failed to open " << fname;
513        goto out;
514    }
515
516    if (TEMP_FAILURE_RETRY(pread64(fd, &s, sizeof(s), offset)) != sizeof(s)) {
517        PERROR << "Failed to read " <<  sizeof(s) << " bytes from " << fname
518               << " offset " << offset;
519        goto out;
520    }
521
522    if (s.header != VERITY_STATE_HEADER) {
523        /* space allocated, but no state written. write default state */
524        *mode = VERITY_MODE_DEFAULT;
525        rc = write_verity_state(fname, offset, *mode);
526        goto out;
527    }
528
529    if (s.version != VERITY_STATE_VERSION) {
530        LERROR << "Unsupported verity state version (" << s.version << ")";
531        goto out;
532    }
533
534    if (s.mode < VERITY_MODE_EIO ||
535        s.mode > VERITY_MODE_LAST) {
536        LERROR << "Unsupported verity mode (" << s.mode << ")";
537        goto out;
538    }
539
540    *mode = s.mode;
541    rc = 0;
542
543out:
544    if (fd != -1) {
545        close(fd);
546    }
547
548    return rc;
549}
550
551static int read_partition(const char *path, uint64_t size)
552{
553    char buf[READ_BUF_SIZE];
554    ssize_t size_read;
555    android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path, O_RDONLY | O_CLOEXEC)));
556
557    if (fd == -1) {
558        PERROR << "Failed to open " << path;
559        return -errno;
560    }
561
562    while (size) {
563        size_read = TEMP_FAILURE_RETRY(read(fd, buf, READ_BUF_SIZE));
564        if (size_read == -1) {
565            PERROR << "Error in reading partition " << path;
566            return -errno;
567        }
568        size -= size_read;
569    }
570
571    return 0;
572}
573
574static int compare_last_signature(struct fstab_rec *fstab, int *match)
575{
576    char tag[METADATA_TAG_MAX_LENGTH + 1];
577    int fd = -1;
578    int rc = -1;
579    off64_t offset = 0;
580    struct fec_handle *f = NULL;
581    struct fec_verity_metadata verity;
582    uint8_t curr[SHA256_DIGEST_LENGTH];
583    uint8_t prev[SHA256_DIGEST_LENGTH];
584
585    *match = 1;
586
587    if (fec_open(&f, fstab->blk_device, O_RDONLY, FEC_VERITY_DISABLE,
588            FEC_DEFAULT_ROOTS) == -1) {
589        PERROR << "Failed to open '" << fstab->blk_device << "'";
590        return rc;
591    }
592
593    // read verity metadata
594    if (fec_verity_get_metadata(f, &verity) == -1) {
595        PERROR << "Failed to get verity metadata '" << fstab->blk_device << "'";
596        goto out;
597    }
598
599    SHA256(verity.signature, sizeof(verity.signature), curr);
600
601    if (snprintf(tag, sizeof(tag), VERITY_LASTSIG_TAG "_%s",
602            basename(fstab->mount_point)) >= (int)sizeof(tag)) {
603        LERROR << "Metadata tag name too long for " << fstab->mount_point;
604        goto out;
605    }
606
607    if (metadata_find(fstab->verity_loc, tag, SHA256_DIGEST_LENGTH,
608            &offset) < 0) {
609        goto out;
610    }
611
612    fd = TEMP_FAILURE_RETRY(open(fstab->verity_loc, O_RDWR | O_SYNC | O_CLOEXEC));
613
614    if (fd == -1) {
615        PERROR << "Failed to open " << fstab->verity_loc;
616        goto out;
617    }
618
619    if (TEMP_FAILURE_RETRY(pread64(fd, prev, sizeof(prev),
620            offset)) != sizeof(prev)) {
621        PERROR << "Failed to read " << sizeof(prev) << " bytes from "
622               << fstab->verity_loc << " offset " << offset;
623        goto out;
624    }
625
626    *match = !memcmp(curr, prev, SHA256_DIGEST_LENGTH);
627
628    if (!*match) {
629        /* update current signature hash */
630        if (TEMP_FAILURE_RETRY(pwrite64(fd, curr, sizeof(curr),
631                offset)) != sizeof(curr)) {
632            PERROR << "Failed to write " << sizeof(curr) << " bytes to "
633                   << fstab->verity_loc << " offset " << offset;
634            goto out;
635        }
636    }
637
638    rc = 0;
639
640out:
641    fec_close(f);
642    return rc;
643}
644
645static int get_verity_state_offset(struct fstab_rec *fstab, off64_t *offset)
646{
647    char tag[METADATA_TAG_MAX_LENGTH + 1];
648
649    if (snprintf(tag, sizeof(tag), VERITY_STATE_TAG "_%s",
650            basename(fstab->mount_point)) >= (int)sizeof(tag)) {
651        LERROR << "Metadata tag name too long for " << fstab->mount_point;
652        return -1;
653    }
654
655    return metadata_find(fstab->verity_loc, tag, sizeof(struct verity_state),
656                offset);
657}
658
659int load_verity_state(struct fstab_rec* fstab, int* mode) {
660    int match = 0;
661    off64_t offset = 0;
662
663    /* unless otherwise specified, use EIO mode */
664    *mode = VERITY_MODE_EIO;
665
666    /* use the kernel parameter if set */
667    std::string veritymode;
668    if (fs_mgr_get_boot_config("veritymode", &veritymode)) {
669        if (veritymode == "enforcing") {
670            *mode = VERITY_MODE_DEFAULT;
671        }
672        return 0;
673    }
674
675    if (get_verity_state_offset(fstab, &offset) < 0) {
676        /* fall back to stateless behavior */
677        return 0;
678    }
679
680    if (was_verity_restart()) {
681        /* device was restarted after dm-verity detected a corrupted
682         * block, so use EIO mode */
683        return write_verity_state(fstab->verity_loc, offset, *mode);
684    }
685
686    if (!compare_last_signature(fstab, &match) && !match) {
687        /* partition has been reflashed, reset dm-verity state */
688        *mode = VERITY_MODE_DEFAULT;
689        return write_verity_state(fstab->verity_loc, offset, *mode);
690    }
691
692    return read_verity_state(fstab->verity_loc, offset, mode);
693}
694
695// Update the verity table using the actual block device path.
696// Two cases:
697// Case-1: verity table is shared for devices with different by-name prefix.
698// Example:
699//   verity table token:       /dev/block/bootdevice/by-name/vendor
700//   blk_device-1 (non-A/B):   /dev/block/platform/soc.0/7824900.sdhci/by-name/vendor
701//   blk_device-2 (A/B):       /dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor_a
702//
703// Case-2: append A/B suffix in the verity table.
704// Example:
705//   verity table token: /dev/block/platform/soc.0/7824900.sdhci/by-name/vendor
706//   blk_device:         /dev/block/platform/soc.0/7824900.sdhci/by-name/vendor_a
707static void update_verity_table_blk_device(const std::string& blk_device, char** table,
708                                           bool slot_select) {
709    bool updated = false;
710    std::string result, ab_suffix;
711    auto tokens = android::base::Split(*table, " ");
712
713    // If slot_select is set, it means blk_device is already updated with ab_suffix.
714    if (slot_select) ab_suffix = fs_mgr_get_slot_suffix();
715
716    for (const auto& token : tokens) {
717        std::string new_token;
718        if (android::base::StartsWith(token, "/dev/block/")) {
719            if (token == blk_device) return;  // no need to update if they're already the same.
720            std::size_t found1 = blk_device.find("by-name");
721            std::size_t found2 = token.find("by-name");
722            if (found1 != std::string::npos && found2 != std::string::npos &&
723                blk_device.substr(found1) == token.substr(found2) + ab_suffix) {
724                new_token = blk_device;
725            }
726        }
727
728        if (!new_token.empty()) {
729            updated = true;
730            LINFO << "Verity table: updated block device from '" << token << "' to '" << new_token
731                  << "'";
732        } else {
733            new_token = token;
734        }
735
736        if (result.empty()) {
737            result = new_token;
738        } else {
739            result += " " + new_token;
740        }
741    }
742
743    if (!updated) {
744        return;
745    }
746
747    free(*table);
748    *table = strdup(result.c_str());
749}
750
751// prepares the verity enabled (MF_VERIFY / MF_VERIFYATBOOT) fstab record for
752// mount. The 'wait_for_verity_dev' parameter makes this function wait for the
753// verity device to get created before return
754int fs_mgr_setup_verity(struct fstab_rec *fstab, bool wait_for_verity_dev)
755{
756    int retval = FS_MGR_SETUP_VERITY_FAIL;
757    int fd = -1;
758    std::string verity_blk_name;
759    struct fec_handle *f = NULL;
760    struct fec_verity_metadata verity;
761    struct verity_table_params params = { .table = NULL };
762
763    alignas(dm_ioctl) char buffer[DM_BUF_SIZE];
764    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
765    const std::string mount_point(basename(fstab->mount_point));
766    bool verified_at_boot = false;
767
768    // This is a public API and so deserves its own check to see if verity
769    // setup is needed at all.
770    if (!is_device_secure()) {
771        LINFO << "Verity setup skipped for " << mount_point;
772        return FS_MGR_SETUP_VERITY_SKIPPED;
773    }
774
775    if (fec_open(&f, fstab->blk_device, O_RDONLY, FEC_VERITY_DISABLE,
776            FEC_DEFAULT_ROOTS) < 0) {
777        PERROR << "Failed to open '" << fstab->blk_device << "'";
778        return retval;
779    }
780
781    // read verity metadata
782    if (fec_verity_get_metadata(f, &verity) < 0) {
783        PERROR << "Failed to get verity metadata '" << fstab->blk_device << "'";
784        // Allow verity disabled when the device is unlocked without metadata
785        if ("0" == android::base::GetProperty("ro.boot.flash.locked", "")) {
786            retval = FS_MGR_SETUP_VERITY_DISABLED;
787            LWARNING << "Allow invalid metadata when the device is unlocked";
788        }
789        goto out;
790    }
791
792#ifdef ALLOW_ADBD_DISABLE_VERITY
793    if (verity.disabled) {
794        retval = FS_MGR_SETUP_VERITY_DISABLED;
795        LINFO << "Attempt to cleanly disable verity - only works in USERDEBUG";
796        goto out;
797    }
798#endif
799
800    // read ecc metadata
801    if (fec_ecc_get_metadata(f, &params.ecc) < 0) {
802        params.ecc.valid = false;
803    }
804
805    params.ecc_dev = fstab->blk_device;
806
807    // get the device mapper fd
808    if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
809        PERROR << "Error opening device mapper";
810        goto out;
811    }
812
813    // create the device
814    if (!fs_mgr_create_verity_device(io, mount_point, fd)) {
815        LERROR << "Couldn't create verity device!";
816        goto out;
817    }
818
819    // get the name of the device file
820    if (!fs_mgr_get_verity_device_name(io, mount_point, fd, &verity_blk_name)) {
821        LERROR << "Couldn't get verity device number!";
822        goto out;
823    }
824
825    if (load_verity_state(fstab, &params.mode) < 0) {
826        /* if accessing or updating the state failed, switch to the default
827         * safe mode. This makes sure the device won't end up in an endless
828         * restart loop, and no corrupted data will be exposed to userspace
829         * without a warning. */
830        params.mode = VERITY_MODE_EIO;
831    }
832
833    if (!verity.table) {
834        goto out;
835    }
836
837    params.table = strdup(verity.table);
838    if (!params.table) {
839        goto out;
840    }
841
842    // verify the signature on the table
843    if (verify_verity_signature(verity) < 0) {
844        if (params.mode == VERITY_MODE_LOGGING) {
845            // the user has been warned, allow mounting without dm-verity
846            retval = FS_MGR_SETUP_VERITY_SUCCESS;
847            goto out;
848        }
849
850        // invalidate root hash and salt to trigger device-specific recovery
851        if (invalidate_table(params.table, verity.table_length) < 0) {
852            goto out;
853        }
854    }
855
856    LINFO << "Enabling dm-verity for " << mount_point.c_str()
857          << " (mode " << params.mode << ")";
858
859    // Update the verity params using the actual block device path
860    update_verity_table_blk_device(fstab->blk_device, &params.table,
861                                   fstab->fs_mgr_flags & MF_SLOTSELECT);
862
863    // load the verity mapping table
864    if (load_verity_table(io, mount_point, verity.data_size, fd, &params,
865            format_verity_table) == 0) {
866        goto loaded;
867    }
868
869    if (params.ecc.valid) {
870        // kernel may not support error correction, try without
871        LINFO << "Disabling error correction for " << mount_point.c_str();
872        params.ecc.valid = false;
873
874        if (load_verity_table(io, mount_point, verity.data_size, fd, &params,
875                format_verity_table) == 0) {
876            goto loaded;
877        }
878    }
879
880    // try the legacy format for backwards compatibility
881    if (load_verity_table(io, mount_point, verity.data_size, fd, &params,
882            format_legacy_verity_table) == 0) {
883        goto loaded;
884    }
885
886    if (params.mode != VERITY_MODE_EIO) {
887        // as a last resort, EIO mode should always be supported
888        LINFO << "Falling back to EIO mode for " << mount_point.c_str();
889        params.mode = VERITY_MODE_EIO;
890
891        if (load_verity_table(io, mount_point, verity.data_size, fd, &params,
892                format_legacy_verity_table) == 0) {
893            goto loaded;
894        }
895    }
896
897    LERROR << "Failed to load verity table for " << mount_point.c_str();
898    goto out;
899
900loaded:
901
902    // activate the device
903    if (!fs_mgr_resume_verity_table(io, mount_point, fd)) {
904        goto out;
905    }
906
907    // mark the underlying block device as read-only
908    fs_mgr_set_blk_ro(fstab->blk_device);
909
910    // Verify the entire partition in one go
911    // If there is an error, allow it to mount as a normal verity partition.
912    if (fstab->fs_mgr_flags & MF_VERIFYATBOOT) {
913        LINFO << "Verifying partition " << fstab->blk_device << " at boot";
914        int err = read_partition(verity_blk_name.c_str(), verity.data_size);
915        if (!err) {
916            LINFO << "Verified verity partition "
917                  << fstab->blk_device << " at boot";
918            verified_at_boot = true;
919        }
920    }
921
922    // assign the new verity block device as the block device
923    if (!verified_at_boot) {
924        free(fstab->blk_device);
925        fstab->blk_device = strdup(verity_blk_name.c_str());
926    } else if (!fs_mgr_destroy_verity_device(io, mount_point, fd)) {
927        LERROR << "Failed to remove verity device " << mount_point.c_str();
928        goto out;
929    }
930
931    // make sure we've set everything up properly
932    if (wait_for_verity_dev && fs_mgr_test_access(fstab->blk_device) < 0) {
933        goto out;
934    }
935
936    retval = FS_MGR_SETUP_VERITY_SUCCESS;
937
938out:
939    if (fd != -1) {
940        close(fd);
941    }
942
943    fec_close(f);
944    free(params.table);
945
946    return retval;
947}
948