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Merge "Restore verity state when verified partition is reflashed"

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Sami Tolvanen 2015-04-07 08:45:34 +00:00 committed by Gerrit Code Review
commit 02f1d80ae2
1 changed files with 117 additions and 20 deletions
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137
fs_mgr/fs_mgr_verity.c
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@ -51,6 +51,8 @@
#define METADATA_TAG_MAX_LENGTH 63
#define METADATA_EOD "eod"
#define VERITY_LASTSIG_TAG "verity_lastsig"
#define VERITY_STATE_TAG "verity_state"
#define VERITY_STATE_HEADER 0x83c0ae9d
#define VERITY_STATE_VERSION 1
@ -179,8 +181,12 @@ static int read_verity_metadata(char *block_device, char **signature, char **tab
int protocol_version;
int device;
int retval = FS_MGR_SETUP_VERITY_FAIL;
*signature = 0;
*table = 0;
*signature = NULL;
if (table) {
*table = NULL;
}
device = TEMP_FAILURE_RETRY(open(block_device, O_RDONLY | O_CLOEXEC));
if (device == -1) {
@ -241,6 +247,11 @@ static int read_verity_metadata(char *block_device, char **signature, char **tab
goto out;
}
if (!table) {
retval = FS_MGR_SETUP_VERITY_SUCCESS;
goto out;
}
// get the size of the table
if (TEMP_FAILURE_RETRY(read(device, &table_length, sizeof(table_length))) !=
sizeof(table_length)) {
@ -268,10 +279,13 @@ out:
TEMP_FAILURE_RETRY(close(device));
if (retval != FS_MGR_SETUP_VERITY_SUCCESS) {
free(*table);
free(*signature);
*table = 0;
*signature = 0;
*signature = NULL;
if (table) {
free(*table);
*table = NULL;
}
}
return retval;
@ -642,12 +656,94 @@ out:
return rc;
}
static int compare_last_signature(struct fstab_rec *fstab, int *match)
{
char tag[METADATA_TAG_MAX_LENGTH + 1];
char *signature = NULL;
int fd = -1;
int rc = -1;
uint8_t curr[SHA256_DIGEST_SIZE];
uint8_t prev[SHA256_DIGEST_SIZE];
off64_t offset = 0;
*match = 1;
if (read_verity_metadata(fstab->blk_device, &signature, NULL) < 0) {
ERROR("Failed to read verity signature from %s\n", fstab->mount_point);
goto out;
}
SHA256_hash(signature, RSANUMBYTES, curr);
if (snprintf(tag, sizeof(tag), VERITY_LASTSIG_TAG "_%s",
basename(fstab->mount_point)) >= (int)sizeof(tag)) {
ERROR("Metadata tag name too long for %s\n", fstab->mount_point);
goto out;
}
if (metadata_find(fstab->verity_loc, tag, SHA256_DIGEST_SIZE,
&offset) < 0) {
goto out;
}
fd = TEMP_FAILURE_RETRY(open(fstab->verity_loc, O_RDWR | O_SYNC | O_CLOEXEC));
if (fd == -1) {
ERROR("Failed to open %s: %s\n", fstab->verity_loc, strerror(errno));
goto out;
}
if (TEMP_FAILURE_RETRY(pread64(fd, prev, sizeof(prev),
offset)) != sizeof(prev)) {
ERROR("Failed to read %zu bytes from %s offset %" PRIu64 " (%s)\n",
sizeof(prev), fstab->verity_loc, offset, strerror(errno));
goto out;
}
*match = !memcmp(curr, prev, SHA256_DIGEST_SIZE);
if (!*match) {
/* update current signature hash */
if (TEMP_FAILURE_RETRY(pwrite64(fd, curr, sizeof(curr),
offset)) != sizeof(curr)) {
ERROR("Failed to write %zu bytes to %s offset %" PRIu64 " (%s)\n",
sizeof(curr), fstab->verity_loc, offset, strerror(errno));
goto out;
}
}
rc = 0;
out:
free(signature);
if (fd != -1) {
TEMP_FAILURE_RETRY(close(fd));
}
return rc;
}
static int get_verity_state_offset(struct fstab_rec *fstab, off64_t *offset)
{
char tag[METADATA_TAG_MAX_LENGTH + 1];
if (snprintf(tag, sizeof(tag), VERITY_STATE_TAG "_%s",
basename(fstab->mount_point)) >= (int)sizeof(tag)) {
ERROR("Metadata tag name too long for %s\n", fstab->mount_point);
return -1;
}
return metadata_find(fstab->verity_loc, tag, sizeof(struct verity_state),
offset);
}
static int load_verity_state(struct fstab_rec *fstab, int *mode)
{
off64_t offset = 0;
int match = 0;
if (metadata_find(fstab->verity_loc, VERITY_STATE_TAG,
sizeof(struct verity_state), &offset) < 0) {
if (get_verity_state_offset(fstab, &offset) < 0) {
/* fall back to stateless behavior */
*mode = VERITY_MODE_EIO;
return 0;
@ -660,6 +756,12 @@ static int load_verity_state(struct fstab_rec *fstab, int *mode)
return write_verity_state(fstab->verity_loc, offset, *mode);
}
if (!compare_last_signature(fstab, &match) && !match) {
/* partition has been reflashed, reset dm-verity state */
*mode = VERITY_MODE_DEFAULT;
return write_verity_state(fstab->verity_loc, offset, *mode);
}
return read_verity_state(fstab->verity_loc, offset, mode);
}
@ -669,8 +771,11 @@ int fs_mgr_load_verity_state(int *mode)
char propbuf[PROPERTY_VALUE_MAX];
int rc = -1;
int i;
int current;
struct fstab *fstab = NULL;
/* return the default mode, unless any of the verified partitions are in
* logging mode, in which case return that */
*mode = VERITY_MODE_DEFAULT;
property_get("ro.hardware", propbuf, "");
@ -688,20 +793,16 @@ int fs_mgr_load_verity_state(int *mode)
continue;
}
rc = load_verity_state(&fstab->recs[i], mode);
rc = load_verity_state(&fstab->recs[i], &current);
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 (current == VERITY_MODE_LOGGING) {
*mode = current;
}
}
/* if there were multiple partitions, all in non-logging mode, return the
* state of the last one */
rc = 0;
out:
@ -749,12 +850,8 @@ 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;
}
if (read_verity_state(fstab->recs[i].verity_loc, offset, &mode) < 0) {
if (get_verity_state_offset(&fstab->recs[i], &offset) < 0 ||
read_verity_state(fstab->recs[i].verity_loc, offset, &mode) < 0) {
continue;
}