fs_mgr_verity.cpp revision 0d1214c68ea95543468b09f7ae27bd65c8c8d7c0 
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 <inttypes.h>
18#include <stdio.h>
19#include <stdlib.h>
20#include <string.h>
21#include <unistd.h>
22#include <fcntl.h>
23#include <ctype.h>
24#include <sys/mount.h>
25#include <sys/stat.h>
26#include <errno.h>
27#include <sys/types.h>
28#include <sys/wait.h>
29#include <libgen.h>
30#include <time.h>
31
32#include <android-base/file.h>
33#include <private/android_filesystem_config.h>
34#include <cutils/properties.h>
35#include <logwrap/logwrap.h>
36
37#include "mincrypt/rsa.h"
38#include "mincrypt/sha.h"
39#include "mincrypt/sha256.h"
40
41#include "fec/io.h"
42
43#include "fs_mgr.h"
44#include "fs_mgr_priv.h"
45#include "fs_mgr_priv_verity.h"
46
47#define FSTAB_PREFIX "/fstab."
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 __STRINGIFY(x) #x
76#define STRINGIFY(x) __STRINGIFY(x)
77
78struct verity_state {
79    uint32_t header;
80    uint32_t version;
81    int32_t mode;
82};
83
84extern struct fs_info info;
85
86static RSAPublicKey *load_key(const char *path)
87{
88    RSAPublicKey* key = static_cast<RSAPublicKey*>(malloc(sizeof(RSAPublicKey)));
89    if (!key) {
90        ERROR("Can't malloc key\n");
91        return NULL;
92    }
93
94    FILE* f = fopen(path, "r");
95    if (!f) {
96        ERROR("Can't open '%s'\n", path);
97        free(key);
98        return NULL;
99    }
100
101    if (!fread(key, sizeof(*key), 1, f)) {
102        ERROR("Could not read key!\n");
103        fclose(f);
104        free(key);
105        return NULL;
106    }
107
108    if (key->len != RSANUMWORDS) {
109        ERROR("Invalid key length %d\n", key->len);
110        fclose(f);
111        free(key);
112        return NULL;
113    }
114
115    fclose(f);
116    return key;
117}
118
119static int verify_table(const uint8_t *signature, const char *table,
120        uint32_t table_length)
121{
122    RSAPublicKey *key;
123    uint8_t hash_buf[SHA256_DIGEST_SIZE];
124    int retval = -1;
125
126    // Hash the table
127    SHA256_hash((uint8_t*)table, table_length, hash_buf);
128
129    // Now get the public key from the keyfile
130    key = load_key(VERITY_TABLE_RSA_KEY);
131    if (!key) {
132        ERROR("Couldn't load verity keys\n");
133        goto out;
134    }
135
136    // verify the result
137    if (!RSA_verify(key,
138                    signature,
139                    RSANUMBYTES,
140                    (uint8_t*) hash_buf,
141                    SHA256_DIGEST_SIZE)) {
142        ERROR("Couldn't verify table\n");
143        goto out;
144    }
145
146    retval = 0;
147
148out:
149    free(key);
150    return retval;
151}
152
153static int invalidate_table(char *table, size_t table_length)
154{
155    size_t n = 0;
156    size_t idx = 0;
157    size_t cleared = 0;
158
159    while (n < table_length) {
160        if (table[n++] == ' ') {
161            ++idx;
162        }
163
164        if (idx != VERITY_TABLE_HASH_IDX && idx != VERITY_TABLE_SALT_IDX) {
165            continue;
166        }
167
168        while (n < table_length && table[n] != ' ') {
169            table[n++] = '0';
170        }
171
172        if (++cleared == 2) {
173            return 0;
174        }
175    }
176
177    return -1;
178}
179
180static void verity_ioctl_init(struct dm_ioctl *io, char *name, unsigned flags)
181{
182    memset(io, 0, DM_BUF_SIZE);
183    io->data_size = DM_BUF_SIZE;
184    io->data_start = sizeof(struct dm_ioctl);
185    io->version[0] = 4;
186    io->version[1] = 0;
187    io->version[2] = 0;
188    io->flags = flags | DM_READONLY_FLAG;
189    if (name) {
190        strlcpy(io->name, name, sizeof(io->name));
191    }
192}
193
194static int create_verity_device(struct dm_ioctl *io, char *name, int fd)
195{
196    verity_ioctl_init(io, name, 1);
197    if (ioctl(fd, DM_DEV_CREATE, io)) {
198        ERROR("Error creating device mapping (%s)", strerror(errno));
199        return -1;
200    }
201    return 0;
202}
203
204static int get_verity_device_name(struct dm_ioctl *io, char *name, int fd, char **dev_name)
205{
206    verity_ioctl_init(io, name, 0);
207    if (ioctl(fd, DM_DEV_STATUS, io)) {
208        ERROR("Error fetching verity device number (%s)", strerror(errno));
209        return -1;
210    }
211    int dev_num = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00);
212    if (asprintf(dev_name, "/dev/block/dm-%u", dev_num) < 0) {
213        ERROR("Error getting verity block device name (%s)", strerror(errno));
214        return -1;
215    }
216    return 0;
217}
218
219struct verity_table_params {
220    const char *table;
221    int mode;
222    struct fec_ecc_metadata ecc;
223    const char *ecc_dev;
224};
225
226typedef bool (*format_verity_table_func)(char *buf, const size_t bufsize,
227        const struct verity_table_params *params);
228
229static bool format_verity_table(char *buf, const size_t bufsize,
230        const struct verity_table_params *params)
231{
232    const char *mode_flag = NULL;
233    int res = -1;
234
235    if (params->mode == VERITY_MODE_RESTART) {
236        mode_flag = VERITY_TABLE_OPT_RESTART;
237    } else if (params->mode == VERITY_MODE_LOGGING) {
238        mode_flag = VERITY_TABLE_OPT_LOGGING;
239    }
240
241    if (params->ecc.valid) {
242        if (mode_flag) {
243            res = snprintf(buf, bufsize,
244                    "%s %u %s " VERITY_TABLE_OPT_FEC_FORMAT,
245                    params->table, 1 + VERITY_TABLE_OPT_FEC_ARGS, mode_flag, params->ecc_dev,
246                    params->ecc.start / FEC_BLOCKSIZE, params->ecc.blocks, params->ecc.roots);
247        } else {
248            res = snprintf(buf, bufsize,
249                    "%s %u " VERITY_TABLE_OPT_FEC_FORMAT,
250                    params->table, VERITY_TABLE_OPT_FEC_ARGS, params->ecc_dev,
251                    params->ecc.start / FEC_BLOCKSIZE, params->ecc.blocks, params->ecc.roots);
252        }
253    } else if (mode_flag) {
254        res = snprintf(buf, bufsize, "%s 2 " VERITY_TABLE_OPT_IGNZERO " %s", params->table,
255                    mode_flag);
256    } else {
257        res = strlcpy(buf, params->table, bufsize);
258    }
259
260    if (res < 0 || (size_t)res >= bufsize) {
261        ERROR("Error building verity table; insufficient buffer size?\n");
262        return false;
263    }
264
265    return true;
266}
267
268static bool format_legacy_verity_table(char *buf, const size_t bufsize,
269        const struct verity_table_params *params)
270{
271    int res;
272
273    if (params->mode == VERITY_MODE_EIO) {
274        res = strlcpy(buf, params->table, bufsize);
275    } else {
276        res = snprintf(buf, bufsize, "%s %d", params->table, params->mode);
277    }
278
279    if (res < 0 || (size_t)res >= bufsize) {
280        ERROR("Error building verity table; insufficient buffer size?\n");
281        return false;
282    }
283
284    return true;
285}
286
287static int load_verity_table(struct dm_ioctl *io, char *name, uint64_t device_size, int fd,
288        const struct verity_table_params *params, format_verity_table_func format)
289{
290    char *verity_params;
291    char *buffer = (char*) io;
292    size_t bufsize;
293
294    verity_ioctl_init(io, name, DM_STATUS_TABLE_FLAG);
295
296    struct dm_target_spec *tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)];
297
298    // set tgt arguments
299    io->target_count = 1;
300    tgt->status = 0;
301    tgt->sector_start = 0;
302    tgt->length = device_size / 512;
303    strcpy(tgt->target_type, "verity");
304
305    // build the verity params
306    verity_params = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec);
307    bufsize = DM_BUF_SIZE - (verity_params - buffer);
308
309    if (!format(verity_params, bufsize, params)) {
310        ERROR("Failed to format verity parameters\n");
311        return -1;
312    }
313
314    INFO("loading verity table: '%s'", verity_params);
315
316    // set next target boundary
317    verity_params += strlen(verity_params) + 1;
318    verity_params = (char*)(((unsigned long)verity_params + 7) & ~8);
319    tgt->next = verity_params - buffer;
320
321    // send the ioctl to load the verity table
322    if (ioctl(fd, DM_TABLE_LOAD, io)) {
323        ERROR("Error loading verity table (%s)\n", strerror(errno));
324        return -1;
325    }
326
327    return 0;
328}
329
330static int resume_verity_table(struct dm_ioctl *io, char *name, int fd)
331{
332    verity_ioctl_init(io, name, 0);
333    if (ioctl(fd, DM_DEV_SUSPEND, io)) {
334        ERROR("Error activating verity device (%s)", strerror(errno));
335        return -1;
336    }
337    return 0;
338}
339
340static int test_access(char *device) {
341    int tries = 25;
342    while (tries--) {
343        if (!access(device, F_OK) || errno != ENOENT) {
344            return 0;
345        }
346        usleep(40 * 1000);
347    }
348    return -1;
349}
350
351static int check_verity_restart(const char *fname)
352{
353    char buffer[VERITY_KMSG_BUFSIZE + 1];
354    int fd;
355    int rc = 0;
356    ssize_t size;
357    struct stat s;
358
359    fd = TEMP_FAILURE_RETRY(open(fname, O_RDONLY | O_CLOEXEC));
360
361    if (fd == -1) {
362        if (errno != ENOENT) {
363            ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
364        }
365        goto out;
366    }
367
368    if (fstat(fd, &s) == -1) {
369        ERROR("Failed to fstat %s (%s)\n", fname, strerror(errno));
370        goto out;
371    }
372
373    size = VERITY_KMSG_BUFSIZE;
374
375    if (size > s.st_size) {
376        size = s.st_size;
377    }
378
379    if (lseek(fd, s.st_size - size, SEEK_SET) == -1) {
380        ERROR("Failed to lseek %jd %s (%s)\n", (intmax_t)(s.st_size - size), fname,
381            strerror(errno));
382        goto out;
383    }
384
385    if (!android::base::ReadFully(fd, buffer, size)) {
386        ERROR("Failed to read %zd bytes from %s (%s)\n", size, fname,
387            strerror(errno));
388        goto out;
389    }
390
391    buffer[size] = '\0';
392
393    if (strstr(buffer, VERITY_KMSG_RESTART) != NULL) {
394        rc = 1;
395    }
396
397out:
398    if (fd != -1) {
399        close(fd);
400    }
401
402    return rc;
403}
404
405static int was_verity_restart()
406{
407    static const char *files[] = {
408        "/sys/fs/pstore/console-ramoops",
409        "/proc/last_kmsg",
410        NULL
411    };
412    int i;
413
414    for (i = 0; files[i]; ++i) {
415        if (check_verity_restart(files[i])) {
416            return 1;
417        }
418    }
419
420    return 0;
421}
422
423static int metadata_add(FILE *fp, long start, const char *tag,
424        unsigned int length, off64_t *offset)
425{
426    if (fseek(fp, start, SEEK_SET) < 0 ||
427        fprintf(fp, "%s %u\n", tag, length) < 0) {
428        return -1;
429    }
430
431    *offset = ftell(fp);
432
433    if (fseek(fp, length, SEEK_CUR) < 0 ||
434        fprintf(fp, METADATA_EOD " 0\n") < 0) {
435        return -1;
436    }
437
438    return 0;
439}
440
441static int metadata_find(const char *fname, const char *stag,
442        unsigned int slength, off64_t *offset)
443{
444    FILE *fp = NULL;
445    char tag[METADATA_TAG_MAX_LENGTH + 1];
446    int rc = -1;
447    int n;
448    long start = 0x4000; /* skip cryptfs metadata area */
449    uint32_t magic;
450    unsigned int length = 0;
451
452    if (!fname) {
453        return -1;
454    }
455
456    fp = fopen(fname, "r+");
457
458    if (!fp) {
459        ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
460        goto out;
461    }
462
463    /* check magic */
464    if (fseek(fp, start, SEEK_SET) < 0 ||
465        fread(&magic, sizeof(magic), 1, fp) != 1) {
466        ERROR("Failed to read magic from %s (%s)\n", fname, strerror(errno));
467        goto out;
468    }
469
470    if (magic != METADATA_MAGIC) {
471        magic = METADATA_MAGIC;
472
473        if (fseek(fp, start, SEEK_SET) < 0 ||
474            fwrite(&magic, sizeof(magic), 1, fp) != 1) {
475            ERROR("Failed to write magic to %s (%s)\n", fname, strerror(errno));
476            goto out;
477        }
478
479        rc = metadata_add(fp, start + sizeof(magic), stag, slength, offset);
480        if (rc < 0) {
481            ERROR("Failed to add metadata to %s: %s\n", fname, strerror(errno));
482        }
483
484        goto out;
485    }
486
487    start += sizeof(magic);
488
489    while (1) {
490        n = fscanf(fp, "%" STRINGIFY(METADATA_TAG_MAX_LENGTH) "s %u\n",
491                tag, &length);
492
493        if (n == 2 && strcmp(tag, METADATA_EOD)) {
494            /* found a tag */
495            start = ftell(fp);
496
497            if (!strcmp(tag, stag) && length == slength) {
498                *offset = start;
499                rc = 0;
500                goto out;
501            }
502
503            start += length;
504
505            if (fseek(fp, length, SEEK_CUR) < 0) {
506                ERROR("Failed to seek %s (%s)\n", fname, strerror(errno));
507                goto out;
508            }
509        } else {
510            rc = metadata_add(fp, start, stag, slength, offset);
511            if (rc < 0) {
512                ERROR("Failed to write metadata to %s: %s\n", fname,
513                    strerror(errno));
514            }
515            goto out;
516        }
517   }
518
519out:
520    if (fp) {
521        fflush(fp);
522        fclose(fp);
523    }
524
525    return rc;
526}
527
528static int write_verity_state(const char *fname, off64_t offset, int32_t mode)
529{
530    int fd;
531    int rc = -1;
532    struct verity_state s = { VERITY_STATE_HEADER, VERITY_STATE_VERSION, mode };
533
534    fd = TEMP_FAILURE_RETRY(open(fname, O_WRONLY | O_SYNC | O_CLOEXEC));
535
536    if (fd == -1) {
537        ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
538        goto out;
539    }
540
541    if (TEMP_FAILURE_RETRY(pwrite64(fd, &s, sizeof(s), offset)) != sizeof(s)) {
542        ERROR("Failed to write %zu bytes to %s to offset %" PRIu64 " (%s)\n",
543            sizeof(s), fname, offset, strerror(errno));
544        goto out;
545    }
546
547    rc = 0;
548
549out:
550    if (fd != -1) {
551        close(fd);
552    }
553
554    return rc;
555}
556
557static int read_verity_state(const char *fname, off64_t offset, int *mode)
558{
559    int fd = -1;
560    int rc = -1;
561    struct verity_state s;
562
563    fd = TEMP_FAILURE_RETRY(open(fname, O_RDONLY | O_CLOEXEC));
564
565    if (fd == -1) {
566        ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
567        goto out;
568    }
569
570    if (TEMP_FAILURE_RETRY(pread64(fd, &s, sizeof(s), offset)) != sizeof(s)) {
571        ERROR("Failed to read %zu bytes from %s offset %" PRIu64 " (%s)\n",
572            sizeof(s), fname, offset, strerror(errno));
573        goto out;
574    }
575
576    if (s.header != VERITY_STATE_HEADER) {
577        /* space allocated, but no state written. write default state */
578        *mode = VERITY_MODE_DEFAULT;
579        rc = write_verity_state(fname, offset, *mode);
580        goto out;
581    }
582
583    if (s.version != VERITY_STATE_VERSION) {
584        ERROR("Unsupported verity state version (%u)\n", s.version);
585        goto out;
586    }
587
588    if (s.mode < VERITY_MODE_EIO ||
589        s.mode > VERITY_MODE_LAST) {
590        ERROR("Unsupported verity mode (%u)\n", s.mode);
591        goto out;
592    }
593
594    *mode = s.mode;
595    rc = 0;
596
597out:
598    if (fd != -1) {
599        close(fd);
600    }
601
602    return rc;
603}
604
605static int compare_last_signature(struct fstab_rec *fstab, int *match)
606{
607    char tag[METADATA_TAG_MAX_LENGTH + 1];
608    int fd = -1;
609    int rc = -1;
610    off64_t offset = 0;
611    struct fec_handle *f = NULL;
612    struct fec_verity_metadata verity;
613    uint8_t curr[SHA256_DIGEST_SIZE];
614    uint8_t prev[SHA256_DIGEST_SIZE];
615
616    *match = 1;
617
618    if (fec_open(&f, fstab->blk_device, O_RDONLY, FEC_VERITY_DISABLE,
619            FEC_DEFAULT_ROOTS) == -1) {
620        ERROR("Failed to open '%s' (%s)\n", fstab->blk_device,
621            strerror(errno));
622        return rc;
623    }
624
625    // read verity metadata
626    if (fec_verity_get_metadata(f, &verity) == -1) {
627        ERROR("Failed to get verity metadata '%s' (%s)\n", fstab->blk_device,
628            strerror(errno));
629        goto out;
630    }
631
632    SHA256_hash(verity.signature, RSANUMBYTES, curr);
633
634    if (snprintf(tag, sizeof(tag), VERITY_LASTSIG_TAG "_%s",
635            basename(fstab->mount_point)) >= (int)sizeof(tag)) {
636        ERROR("Metadata tag name too long for %s\n", fstab->mount_point);
637        goto out;
638    }
639
640    if (metadata_find(fstab->verity_loc, tag, SHA256_DIGEST_SIZE,
641            &offset) < 0) {
642        goto out;
643    }
644
645    fd = TEMP_FAILURE_RETRY(open(fstab->verity_loc, O_RDWR | O_SYNC | O_CLOEXEC));
646
647    if (fd == -1) {
648        ERROR("Failed to open %s: %s\n", fstab->verity_loc, strerror(errno));
649        goto out;
650    }
651
652    if (TEMP_FAILURE_RETRY(pread64(fd, prev, sizeof(prev),
653            offset)) != sizeof(prev)) {
654        ERROR("Failed to read %zu bytes from %s offset %" PRIu64 " (%s)\n",
655            sizeof(prev), fstab->verity_loc, offset, strerror(errno));
656        goto out;
657    }
658
659    *match = !memcmp(curr, prev, SHA256_DIGEST_SIZE);
660
661    if (!*match) {
662        /* update current signature hash */
663        if (TEMP_FAILURE_RETRY(pwrite64(fd, curr, sizeof(curr),
664                offset)) != sizeof(curr)) {
665            ERROR("Failed to write %zu bytes to %s offset %" PRIu64 " (%s)\n",
666                sizeof(curr), fstab->verity_loc, offset, strerror(errno));
667            goto out;
668        }
669    }
670
671    rc = 0;
672
673out:
674    fec_close(f);
675    return rc;
676}
677
678static int get_verity_state_offset(struct fstab_rec *fstab, off64_t *offset)
679{
680    char tag[METADATA_TAG_MAX_LENGTH + 1];
681
682    if (snprintf(tag, sizeof(tag), VERITY_STATE_TAG "_%s",
683            basename(fstab->mount_point)) >= (int)sizeof(tag)) {
684        ERROR("Metadata tag name too long for %s\n", fstab->mount_point);
685        return -1;
686    }
687
688    return metadata_find(fstab->verity_loc, tag, sizeof(struct verity_state),
689                offset);
690}
691
692static int load_verity_state(struct fstab_rec *fstab, int *mode)
693{
694    char propbuf[PROPERTY_VALUE_MAX];
695    int match = 0;
696    off64_t offset = 0;
697
698    /* unless otherwise specified, use EIO mode */
699    *mode = VERITY_MODE_EIO;
700
701    /* use the kernel parameter if set */
702    property_get("ro.boot.veritymode", propbuf, "");
703
704    if (*propbuf != '\0') {
705        if (!strcmp(propbuf, "enforcing")) {
706            *mode = VERITY_MODE_DEFAULT;
707        }
708        return 0;
709    }
710
711    if (get_verity_state_offset(fstab, &offset) < 0) {
712        /* fall back to stateless behavior */
713        return 0;
714    }
715
716    if (was_verity_restart()) {
717        /* device was restarted after dm-verity detected a corrupted
718         * block, so use EIO mode */
719        return write_verity_state(fstab->verity_loc, offset, *mode);
720    }
721
722    if (!compare_last_signature(fstab, &match) && !match) {
723        /* partition has been reflashed, reset dm-verity state */
724        *mode = VERITY_MODE_DEFAULT;
725        return write_verity_state(fstab->verity_loc, offset, *mode);
726    }
727
728    return read_verity_state(fstab->verity_loc, offset, mode);
729}
730
731int fs_mgr_load_verity_state(int *mode)
732{
733    char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
734    char propbuf[PROPERTY_VALUE_MAX];
735    int rc = -1;
736    int i;
737    int current;
738    struct fstab *fstab = NULL;
739
740    /* return the default mode, unless any of the verified partitions are in
741     * logging mode, in which case return that */
742    *mode = VERITY_MODE_DEFAULT;
743
744    property_get("ro.hardware", propbuf, "");
745    snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX"%s", propbuf);
746
747    fstab = fs_mgr_read_fstab(fstab_filename);
748
749    if (!fstab) {
750        ERROR("Failed to read %s\n", fstab_filename);
751        goto out;
752    }
753
754    for (i = 0; i < fstab->num_entries; i++) {
755        if (!fs_mgr_is_verified(&fstab->recs[i])) {
756            continue;
757        }
758
759        rc = load_verity_state(&fstab->recs[i], &current);
760        if (rc < 0) {
761            continue;
762        }
763
764        if (current != VERITY_MODE_DEFAULT) {
765            *mode = current;
766            break;
767        }
768    }
769
770    rc = 0;
771
772out:
773    if (fstab) {
774        fs_mgr_free_fstab(fstab);
775    }
776
777    return rc;
778}
779
780int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback)
781{
782    alignas(dm_ioctl) char buffer[DM_BUF_SIZE];
783    char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
784    char *mount_point;
785    char propbuf[PROPERTY_VALUE_MAX];
786    char *status;
787    int fd = -1;
788    int i;
789    int mode;
790    int rc = -1;
791    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
792    struct fstab *fstab = NULL;
793
794    if (!callback) {
795        return -1;
796    }
797
798    if (fs_mgr_load_verity_state(&mode) == -1) {
799        return -1;
800    }
801
802    fd = TEMP_FAILURE_RETRY(open("/dev/device-mapper", O_RDWR | O_CLOEXEC));
803
804    if (fd == -1) {
805        ERROR("Error opening device mapper (%s)\n", strerror(errno));
806        goto out;
807    }
808
809    property_get("ro.hardware", propbuf, "");
810    snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX"%s", propbuf);
811
812    fstab = fs_mgr_read_fstab(fstab_filename);
813
814    if (!fstab) {
815        ERROR("Failed to read %s\n", fstab_filename);
816        goto out;
817    }
818
819    for (i = 0; i < fstab->num_entries; i++) {
820        if (!fs_mgr_is_verified(&fstab->recs[i])) {
821            continue;
822        }
823
824        mount_point = basename(fstab->recs[i].mount_point);
825        verity_ioctl_init(io, mount_point, 0);
826
827        if (ioctl(fd, DM_TABLE_STATUS, io)) {
828            ERROR("Failed to query DM_TABLE_STATUS for %s (%s)\n", mount_point,
829                strerror(errno));
830            continue;
831        }
832
833        status = &buffer[io->data_start + sizeof(struct dm_target_spec)];
834
835        callback(&fstab->recs[i], mount_point, mode, *status);
836    }
837
838    rc = 0;
839
840out:
841    if (fstab) {
842        fs_mgr_free_fstab(fstab);
843    }
844
845    if (fd) {
846        close(fd);
847    }
848
849    return rc;
850}
851
852int fs_mgr_setup_verity(struct fstab_rec *fstab)
853{
854    int retval = FS_MGR_SETUP_VERITY_FAIL;
855    int fd = -1;
856    char *invalid_table = NULL;
857    char *verity_blk_name = NULL;
858    struct fec_handle *f = NULL;
859    struct fec_verity_metadata verity;
860    struct verity_table_params params;
861
862    alignas(dm_ioctl) char buffer[DM_BUF_SIZE];
863    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
864    char *mount_point = basename(fstab->mount_point);
865
866    if (fec_open(&f, fstab->blk_device, O_RDONLY, FEC_VERITY_DISABLE,
867            FEC_DEFAULT_ROOTS) < 0) {
868        ERROR("Failed to open '%s' (%s)\n", fstab->blk_device,
869            strerror(errno));
870        return retval;
871    }
872
873    // read verity metadata
874    if (fec_verity_get_metadata(f, &verity) < 0) {
875        ERROR("Failed to get verity metadata '%s' (%s)\n", fstab->blk_device,
876            strerror(errno));
877        goto out;
878    }
879
880#ifdef ALLOW_ADBD_DISABLE_VERITY
881    if (verity.disabled) {
882        retval = FS_MGR_SETUP_VERITY_DISABLED;
883        INFO("Attempt to cleanly disable verity - only works in USERDEBUG\n");
884        goto out;
885    }
886#endif
887
888    // read ecc metadata
889    if (fec_ecc_get_metadata(f, &params.ecc) < 0) {
890        params.ecc.valid = false;
891    }
892
893    params.ecc_dev = fstab->blk_device;
894
895    // get the device mapper fd
896    if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
897        ERROR("Error opening device mapper (%s)\n", strerror(errno));
898        goto out;
899    }
900
901    // create the device
902    if (create_verity_device(io, mount_point, fd) < 0) {
903        ERROR("Couldn't create verity device!\n");
904        goto out;
905    }
906
907    // get the name of the device file
908    if (get_verity_device_name(io, mount_point, fd, &verity_blk_name) < 0) {
909        ERROR("Couldn't get verity device number!\n");
910        goto out;
911    }
912
913    if (load_verity_state(fstab, &params.mode) < 0) {
914        /* if accessing or updating the state failed, switch to the default
915         * safe mode. This makes sure the device won't end up in an endless
916         * restart loop, and no corrupted data will be exposed to userspace
917         * without a warning. */
918        params.mode = VERITY_MODE_EIO;
919    }
920
921    // verify the signature on the table
922    if (verify_table(verity.signature, verity.table,
923            verity.table_length) < 0) {
924        if (params.mode == VERITY_MODE_LOGGING) {
925            // the user has been warned, allow mounting without dm-verity
926            retval = FS_MGR_SETUP_VERITY_SUCCESS;
927            goto out;
928        }
929
930        // invalidate root hash and salt to trigger device-specific recovery
931        invalid_table = strdup(verity.table);
932
933        if (!invalid_table ||
934                invalidate_table(invalid_table, verity.table_length) < 0) {
935            goto out;
936        }
937
938        params.table = invalid_table;
939    } else {
940        params.table = verity.table;
941    }
942
943    INFO("Enabling dm-verity for %s (mode %d)\n", mount_point, params.mode);
944
945    // load the verity mapping table
946    if (load_verity_table(io, mount_point, verity.data_size, fd, &params,
947            format_verity_table) < 0 &&
948        // try the legacy format for backwards compatibility
949        load_verity_table(io, mount_point, verity.data_size, fd, &params,
950            format_legacy_verity_table) < 0) {
951        goto out;
952    }
953
954    // activate the device
955    if (resume_verity_table(io, mount_point, fd) < 0) {
956        goto out;
957    }
958
959    // mark the underlying block device as read-only
960    fs_mgr_set_blk_ro(fstab->blk_device);
961
962    // assign the new verity block device as the block device
963    free(fstab->blk_device);
964    fstab->blk_device = verity_blk_name;
965    verity_blk_name = 0;
966
967    // make sure we've set everything up properly
968    if (test_access(fstab->blk_device) < 0) {
969        goto out;
970    }
971
972    retval = FS_MGR_SETUP_VERITY_SUCCESS;
973
974out:
975    if (fd != -1) {
976        close(fd);
977    }
978
979    fec_close(f);
980    free(invalid_table);
981    free(verity_blk_name);
982
983    return retval;
984}
985