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Merge "Use structured format for verity metadata"

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This commit is contained in:
Sami Tolvanen 2015-03-26 07:38:14 +00:00 committed by Gerrit Code Review
commit d33c6c0ef2
3 changed files with 205 additions and 71 deletions
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10
fs_mgr/fs_mgr_fstab.c
View file

@ -24,6 +24,7 @@
struct fs_mgr_flag_values {
char *key_loc;
char *verity_loc;
long long part_length;
char *label;
int partnum;
@ -107,6 +108,14 @@ static int parse_flags(char *flags, struct flag_list *fl,
* location of the keys. Get it and return it.
*/
flag_vals->key_loc = strdup(strchr(p, '=') + 1);
} else if ((fl[i].flag == MF_VERIFY) && flag_vals) {
/* If the verify flag is followed by an = and the
* location for the verity state, get it and return it.
*/
char *start = strchr(p, '=');
if (start) {
flag_vals->verity_loc = strdup(start + 1);
}
} else if ((fl[i].flag == MF_FORCECRYPT) && flag_vals) {
/* The forceencrypt flag is followed by an = and the
* location of the keys. Get it and return it.
@ -291,6 +300,7 @@ struct fstab *fs_mgr_read_fstab(const char *fstab_path)
fstab->recs[cnt].fs_mgr_flags = parse_flags(p, fs_mgr_flags,
&flag_vals, NULL, 0);
fstab->recs[cnt].key_loc = flag_vals.key_loc;
fstab->recs[cnt].verity_loc = flag_vals.verity_loc;
fstab->recs[cnt].length = flag_vals.part_length;
fstab->recs[cnt].label = flag_vals.label;
fstab->recs[cnt].partnum = flag_vals.partnum;

263
fs_mgr/fs_mgr_verity.c
View file

@ -47,16 +47,23 @@
#define VERITY_METADATA_SIZE 32768
#define VERITY_TABLE_RSA_KEY "/verity_key"
#define METADATA_MAGIC 0x01564c54
#define METADATA_TAG_MAX_LENGTH 63
#define METADATA_EOD "eod"
#define VERITY_STATE_TAG "verity_state"
#define VERITY_STATE_HEADER 0x83c0ae9d
#define VERITY_STATE_VERSION 1
#define VERITY_KMSG_RESTART "dm-verity device corrupted"
#define VERITY_KMSG_BUFSIZE 1024
#define __STRINGIFY(x) #x
#define STRINGIFY(x) __STRINGIFY(x)
struct verity_state {
uint32_t header;
uint32_t version;
uint32_t size;
int32_t mode;
};
@ -453,17 +460,117 @@ static int was_verity_restart()
return 0;
}
static int metadata_add(FILE *fp, long start, const char *tag,
unsigned int length, off64_t *offset)
{
if (TEMP_FAILURE_RETRY(fseek(fp, start, SEEK_SET)) < 0 ||
TEMP_FAILURE_RETRY(fprintf(fp, "%s %u\n", tag, length)) < 0) {
return -1;
}
*offset = ftell(fp);
if (TEMP_FAILURE_RETRY(fseek(fp, length, SEEK_CUR)) < 0 ||
TEMP_FAILURE_RETRY(fprintf(fp, METADATA_EOD " 0\n")) < 0) {
return -1;
}
return 0;
}
static int metadata_find(const char *fname, const char *stag,
unsigned int slength, off64_t *offset)
{
FILE *fp = NULL;
char tag[METADATA_TAG_MAX_LENGTH + 1];
int rc = -1;
int n;
long start = 0x4000; /* skip cryptfs metadata area */
uint32_t magic;
unsigned int length = 0;
if (!fname) {
return -1;
}
fp = TEMP_FAILURE_RETRY(fopen(fname, "r+"));
if (!fp) {
ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
goto out;
}
/* check magic */
if (TEMP_FAILURE_RETRY(fseek(fp, start, SEEK_SET)) < 0 ||
TEMP_FAILURE_RETRY(fread(&magic, sizeof(magic), 1, fp)) != 1) {
ERROR("Failed to read magic from %s (%s)\n", fname, strerror(errno));
goto out;
}
if (magic != METADATA_MAGIC) {
magic = METADATA_MAGIC;
if (TEMP_FAILURE_RETRY(fseek(fp, start, SEEK_SET)) < 0 ||
TEMP_FAILURE_RETRY(fwrite(&magic, sizeof(magic), 1, fp)) != 1) {
ERROR("Failed to write magic to %s (%s)\n", fname, strerror(errno));
goto out;
}
rc = metadata_add(fp, start + sizeof(magic), stag, slength, offset);
if (rc < 0) {
ERROR("Failed to add metadata to %s: %s\n", fname, strerror(errno));
}
goto out;
}
start += sizeof(magic);
while (1) {
n = TEMP_FAILURE_RETRY(fscanf(fp,
"%" STRINGIFY(METADATA_TAG_MAX_LENGTH) "s %u\n",
tag, &length));
if (n == 2 && strcmp(tag, METADATA_EOD)) {
/* found a tag */
start = ftell(fp);
if (!strcmp(tag, stag) && length == slength) {
*offset = start;
rc = 0;
goto out;
}
start += length;
if (TEMP_FAILURE_RETRY(fseek(fp, length, SEEK_CUR)) < 0) {
ERROR("Failed to seek %s (%s)\n", fname, strerror(errno));
goto out;
}
} else {
rc = metadata_add(fp, start, stag, slength, offset);
if (rc < 0) {
ERROR("Failed to write metadata to %s: %s\n", fname,
strerror(errno));
}
goto out;
}
}
out:
if (fp) {
TEMP_FAILURE_RETRY(fflush(fp));
TEMP_FAILURE_RETRY(fclose(fp));
}
return rc;
}
static int write_verity_state(const char *fname, off64_t offset, int32_t mode)
{
int fd;
int rc = -1;
struct verity_state s = {
VERITY_STATE_HEADER,
VERITY_STATE_VERSION,
sizeof(struct verity_state),
mode
};
struct verity_state s = { VERITY_STATE_HEADER, VERITY_STATE_VERSION, mode };
fd = TEMP_FAILURE_RETRY(open(fname, O_WRONLY | O_SYNC | O_CLOEXEC));
@ -472,13 +579,9 @@ static int write_verity_state(const char *fname, off64_t offset, int32_t mode)
goto out;
}
if (TEMP_FAILURE_RETRY(lseek64(fd, offset, SEEK_SET)) < 0) {
ERROR("Failed to seek %s to %" PRIu64 " (%s)\n", fname, offset, strerror(errno));
goto out;
}
if (TEMP_FAILURE_RETRY(write(fd, &s, sizeof(s))) != sizeof(s)) {
ERROR("Failed to write %zu bytes to %s (%s)\n", sizeof(s), fname, strerror(errno));
if (TEMP_FAILURE_RETRY(pwrite64(fd, &s, sizeof(s), offset)) != sizeof(s)) {
ERROR("Failed to write %zu bytes to %s to offset %" PRIu64 " (%s)\n",
sizeof(s), fname, offset, strerror(errno));
goto out;
}
@ -492,44 +595,16 @@ out:
return rc;
}
static int get_verity_state_location(char *location, off64_t *offset)
static int load_verity_state(struct fstab_rec *fstab, int *mode)
{
char state_off[PROPERTY_VALUE_MAX];
if (property_get("ro.verity.state.location", location, NULL) <= 0) {
return -1;
}
if (*location != '/' || access(location, R_OK | W_OK) == -1) {
ERROR("Failed to access verity state %s (%s)\n", location, strerror(errno));
return -1;
}
*offset = 0;
if (property_get("ro.verity.state.offset", state_off, NULL) > 0) {
*offset = strtoll(state_off, NULL, 0);
if (errno == ERANGE || errno == EINVAL) {
ERROR("Invalid value in ro.verity.state.offset (%s)\n", state_off);
return -1;
}
}
return 0;
}
int fs_mgr_load_verity_state(int *mode)
{
char fname[PROPERTY_VALUE_MAX];
int fd = -1;
int rc = -1;
off64_t offset = 0;
struct verity_state s;
if (get_verity_state_location(fname, &offset) < 0) {
/* location for dm-verity state is not specified, fall back to
* default behavior: return -EIO for corrupted blocks */
if (metadata_find(fstab->verity_loc, VERITY_STATE_TAG, sizeof(s),
&offset) < 0) {
/* fall back to stateless behavior */
*mode = VERITY_MODE_EIO;
rc = 0;
goto out;
@ -539,28 +614,27 @@ int fs_mgr_load_verity_state(int *mode)
/* device was restarted after dm-verity detected a corrupted
* block, so switch to logging mode */
*mode = VERITY_MODE_LOGGING;
rc = write_verity_state(fname, offset, *mode);
rc = write_verity_state(fstab->verity_loc, offset, *mode);
goto out;
}
fd = TEMP_FAILURE_RETRY(open(fname, O_RDONLY | O_CLOEXEC));
fd = TEMP_FAILURE_RETRY(open(fstab->verity_loc, O_RDONLY | O_CLOEXEC));
if (fd == -1) {
ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
ERROR("Failed to open %s (%s)\n", fstab->verity_loc, strerror(errno));
goto out;
}
if (TEMP_FAILURE_RETRY(lseek64(fd, offset, SEEK_SET)) < 0) {
ERROR("Failed to seek %s to %" PRIu64 " (%s)\n", fname, offset, strerror(errno));
goto out;
}
if (TEMP_FAILURE_RETRY(read(fd, &s, sizeof(s))) != sizeof(s)) {
ERROR("Failed to read %zu bytes from %s (%s)\n", sizeof(s), fname, strerror(errno));
if (TEMP_FAILURE_RETRY(pread64(fd, &s, sizeof(s), offset)) != sizeof(s)) {
ERROR("Failed to read %zu bytes from %s offset %" PRIu64 " (%s)\n",
sizeof(s), fstab->verity_loc, offset, strerror(errno));
goto out;
}
if (s.header != VERITY_STATE_HEADER) {
/* space allocated, but no state written. write default state */
*mode = VERITY_MODE_DEFAULT;
rc = write_verity_state(fstab->verity_loc, offset, *mode);
goto out;
}
@ -569,11 +643,6 @@ int fs_mgr_load_verity_state(int *mode)
goto out;
}
if (s.size != sizeof(s)) {
ERROR("Unexpected verity state size (%u)\n", s.size);
goto out;
}
if (s.mode < VERITY_MODE_EIO ||
s.mode > VERITY_MODE_LAST) {
ERROR("Unsupported verity mode (%u)\n", s.mode);
@ -591,13 +660,61 @@ out:
return rc;
}
int fs_mgr_load_verity_state(int *mode)
{
char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
char propbuf[PROPERTY_VALUE_MAX];
int rc = -1;
int i;
struct fstab *fstab = NULL;
*mode = VERITY_MODE_DEFAULT;
property_get("ro.hardware", propbuf, "");
snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX"%s", propbuf);
fstab = fs_mgr_read_fstab(fstab_filename);
if (!fstab) {
ERROR("Failed to read %s\n", fstab_filename);
goto out;
}
for (i = 0; i < fstab->num_entries; i++) {
if (!fs_mgr_is_verified(&fstab->recs[i])) {
continue;
}
rc = load_verity_state(&fstab->recs[i], mode);
if (rc < 0) {
continue;
}
/* if any of the verified partitions are in logging mode, return */
if (*mode == VERITY_MODE_LOGGING) {
rc = 0;
goto out;
}
}
/* if there were multiple partitions, all in non-logging mode, return the
* state of the last one */
rc = 0;
out:
if (fstab) {
fs_mgr_free_fstab(fstab);
}
return rc;
}
int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback)
{
_Alignas(struct dm_ioctl) char buffer[DM_BUF_SIZE];
char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
char *mount_point;
char propbuf[PROPERTY_VALUE_MAX];
char state_loc[PROPERTY_VALUE_MAX];
char *status;
int fd = -1;
int i;
@ -606,10 +723,6 @@ int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback)
struct dm_ioctl *io = (struct dm_ioctl *) buffer;
struct fstab *fstab = NULL;
if (get_verity_state_location(state_loc, &offset) < 0) {
goto out;
}
fd = TEMP_FAILURE_RETRY(open("/dev/device-mapper", O_RDWR | O_CLOEXEC));
if (fd == -1) {
@ -632,6 +745,11 @@ int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback)
continue;
}
if (metadata_find(fstab->recs[i].verity_loc, VERITY_STATE_TAG,
sizeof(struct verity_state), &offset) < 0) {
continue;
}
mount_point = basename(fstab->recs[i].mount_point);
verity_ioctl_init(io, mount_point, 0);
@ -644,7 +762,8 @@ int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback)
status = &buffer[io->data_start + sizeof(struct dm_target_spec)];
if (*status == 'C') {
rc = write_verity_state(state_loc, offset, VERITY_MODE_LOGGING);
rc = write_verity_state(fstab->recs[i].verity_loc, offset,
VERITY_MODE_LOGGING);
if (rc == -1) {
goto out;
@ -732,8 +851,12 @@ int fs_mgr_setup_verity(struct fstab_rec *fstab) {
goto out;
}
if (fs_mgr_load_verity_state(&mode) < 0) {
mode = VERITY_MODE_RESTART; /* default dm-verity mode */
if (load_verity_state(fstab, &mode) < 0) {
/* if accessing or updating the state failed, switch to the default
* safe mode. This makes sure the device won't end up in an endless
* restart loop, and no corrupted data will be exposed to userspace
* without a warning. */
mode = VERITY_MODE_EIO;
}
INFO("Enabling dm-verity for %s (mode %d)\n", mount_point, mode);

3
fs_mgr/include/fs_mgr.h
View file

@ -36,7 +36,8 @@ enum verity_mode {
VERITY_MODE_EIO = 0,
VERITY_MODE_LOGGING = 1,
VERITY_MODE_RESTART = 2,
VERITY_MODE_LAST = VERITY_MODE_RESTART
VERITY_MODE_LAST = VERITY_MODE_RESTART,
VERITY_MODE_DEFAULT = VERITY_MODE_RESTART
};
/*