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update_verifier: Handle legacy care_map.txt gracefully.

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update_verifier should be backward compatible to not reject legacy
care_map.txt from old releases, which could otherwise fail to boot into
the new release.

For example, we've changed the care_map format between N and O. An O
update_verifier would fail to work with an N care_map.txt - a) we have
switched update_verifier to read from device mapper in O; b) the last
few blocks that contain metadata can't be read via device mapper. This
could be a result of sideloading an O OTA while the device having a
pending N update.

Bug: 63544345
Test: As follows on sailfish:
 1. Flash the device with this CL;
 2. Put a copy of N care_map.txt at /data/ota_package/. Restore the
    permissions properly ('cache' group);
 3. `adb reboot bootloader`;
 4. `fastboot set_active <current_slot>`
 5. Device boots up into home screen, with a warning in logcat that says
    it has skipped legacy care_map.txt.
Change-Id: I6acc88c9e655a9245e6531f176fef7953953935f
This commit is contained in:
Tao Bao 2017-07-21 15:15:31 -07:00
parent 9187f1cc51
commit 5a1dee01df
1 changed files with 45 additions and 32 deletions
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77
update_verifier/update_verifier.cpp
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@ -175,40 +175,53 @@ static bool read_blocks(const std::string& partition, const std::string& range_s
return true;
}
// Returns true to indicate a passing verification (or the error should be ignored); Otherwise
// returns false on fatal errors, where we should reject the current boot and trigger a fallback.
// Note that update_verifier should be backward compatible to not reject care_map.txt from old
// releases, which could otherwise fail to boot into the new release. For example, we've changed
// the care_map format between N and O. An O update_verifier would fail to work with N
// care_map.txt. This could be a result of sideloading an O OTA while the device having a pending N
// update.
bool verify_image(const std::string& care_map_name) {
android::base::unique_fd care_map_fd(TEMP_FAILURE_RETRY(open(care_map_name.c_str(), O_RDONLY)));
// If the device is flashed before the current boot, it may not have care_map.txt
// in /data/ota_package. To allow the device to continue booting in this situation,
// we should print a warning and skip the block verification.
if (care_map_fd.get() == -1) {
PLOG(WARNING) << "Failed to open " << care_map_name;
return true;
}
// Care map file has four lines (two lines if vendor partition is not present):
// First line has the block partition name (system/vendor).
// Second line holds all ranges of blocks to verify.
// The next two lines have the same format but for vendor partition.
std::string file_content;
if (!android::base::ReadFdToString(care_map_fd.get(), &file_content)) {
LOG(ERROR) << "Error reading care map contents to string.";
return false;
}
std::vector<std::string> lines;
lines = android::base::Split(android::base::Trim(file_content), "\n");
if (lines.size() != 2 && lines.size() != 4) {
LOG(ERROR) << "Invalid lines in care_map: found " << lines.size()
<< " lines, expecting 2 or 4 lines.";
return false;
}
for (size_t i = 0; i < lines.size(); i += 2) {
if (!read_blocks(lines[i], lines[i+1])) {
return false;
}
}
android::base::unique_fd care_map_fd(TEMP_FAILURE_RETRY(open(care_map_name.c_str(), O_RDONLY)));
// If the device is flashed before the current boot, it may not have care_map.txt
// in /data/ota_package. To allow the device to continue booting in this situation,
// we should print a warning and skip the block verification.
if (care_map_fd.get() == -1) {
PLOG(WARNING) << "Failed to open " << care_map_name;
return true;
}
// Care map file has four lines (two lines if vendor partition is not present):
// First line has the block partition name (system/vendor).
// Second line holds all ranges of blocks to verify.
// The next two lines have the same format but for vendor partition.
std::string file_content;
if (!android::base::ReadFdToString(care_map_fd.get(), &file_content)) {
LOG(ERROR) << "Error reading care map contents to string.";
return false;
}
std::vector<std::string> lines;
lines = android::base::Split(android::base::Trim(file_content), "\n");
if (lines.size() != 2 && lines.size() != 4) {
LOG(ERROR) << "Invalid lines in care_map: found " << lines.size()
<< " lines, expecting 2 or 4 lines.";
return false;
}
for (size_t i = 0; i < lines.size(); i += 2) {
// We're seeing an N care_map.txt. Skip the verification since it's not compatible with O
// update_verifier (the last few metadata blocks can't be read via device mapper).
if (android::base::StartsWith(lines[i], "/dev/block/")) {
LOG(WARNING) << "Found legacy care_map.txt; skipped.";
return true;
}
if (!read_blocks(lines[i], lines[i+1])) {
return false;
}
}
return true;
}
static int reboot_device() {