fskeyring & userspace reboot: support CE keys
During userspace reboot /data might be unmounted & remounted, meaning
that CE keys stored in fs-level keyring will be lost. In order to be
able to restore them, when installing new key to fs-level keyring, it's
also added to session-level keyring with type "fscrypt-provisioning".
Then when init_user0 is called during userspace reboot, vold will try to
load CE keys from the session-level keyring back into fs-level keyring
for all the users that were unlocked before the reboot.
If for any user vold fails to install the key, init_user0 will fail and
fallback to hard reboot will be triggered.
Test: set a pin pattern
Test: adb shell setprop sys.init.userdata_remount.force_umount 1
Test: adb shell svc power reboot userspace
Test: atest CtsUserspaceRebootHostSideTestCases
Bug: 143970043
Change-Id: I37603dc136c7ededc7b0381e4d730cb0ffd912b4
diff --git a/KeyUtil.cpp b/KeyUtil.cpp
index 6200c42..3359699 100644
--- a/KeyUtil.cpp
+++ b/KeyUtil.cpp
@@ -155,7 +155,7 @@
return true;
}
-// Add an encryption key to the legacy global session keyring.
+// Add an encryption key of type "logon" to the global session keyring.
static bool installKeyLegacy(const KeyBuffer& key, const std::string& raw_ref) {
// Place fscrypt_key into automatically zeroing buffer.
KeyBuffer fsKeyBuffer(sizeof(fscrypt_key));
@@ -178,6 +178,32 @@
return true;
}
+// Installs fscrypt-provisioning key into session level kernel keyring.
+// This allows for the given key to be installed back into filesystem keyring.
+// For more context see reloadKeyFromSessionKeyring.
+static bool installProvisioningKey(const KeyBuffer& key, const std::string& ref,
+ const fscrypt_key_specifier& key_spec) {
+ key_serial_t device_keyring;
+ if (!fscryptKeyring(&device_keyring)) return false;
+
+ // Place fscrypt_provisioning_key_payload into automatically zeroing buffer.
+ KeyBuffer buf(sizeof(fscrypt_provisioning_key_payload) + key.size(), 0);
+ fscrypt_provisioning_key_payload& provisioning_key =
+ *reinterpret_cast<fscrypt_provisioning_key_payload*>(buf.data());
+ memcpy(provisioning_key.raw, key.data(), key.size());
+ provisioning_key.type = key_spec.type;
+
+ key_serial_t key_id = add_key("fscrypt-provisioning", ref.c_str(), (void*)&provisioning_key,
+ buf.size(), device_keyring);
+ if (key_id == -1) {
+ PLOG(ERROR) << "Failed to insert fscrypt-provisioning key for " << ref
+ << " into session keyring";
+ return false;
+ }
+ LOG(DEBUG) << "Added fscrypt-provisioning key for " << ref << " to session keyring";
+ return true;
+}
+
// Build a struct fscrypt_key_specifier for use in the key management ioctls.
static bool buildKeySpecifier(fscrypt_key_specifier* spec, const EncryptionPolicy& policy) {
switch (policy.options.version) {
@@ -205,6 +231,34 @@
}
}
+// Installs key into keyring of a filesystem mounted on |mountpoint|.
+//
+// It's callers responsibility to fill key specifier, and either arg->raw or arg->key_id.
+//
+// In case arg->key_spec.type equals to FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER
+// arg->key_spec.u.identifier will be populated with raw key reference generated
+// by kernel.
+//
+// For documentation on difference between arg->raw and arg->key_id see
+// https://www.kernel.org/doc/html/latest/filesystems/fscrypt.html#fs-ioc-add-encryption-key
+static bool installFsKeyringKey(const std::string& mountpoint, const EncryptionOptions& options,
+ fscrypt_add_key_arg* arg) {
+ if (options.use_hw_wrapped_key) arg->flags |= FSCRYPT_ADD_KEY_FLAG_WRAPPED;
+
+ android::base::unique_fd fd(open(mountpoint.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC));
+ if (fd == -1) {
+ PLOG(ERROR) << "Failed to open " << mountpoint << " to install key";
+ return false;
+ }
+
+ if (ioctl(fd, FS_IOC_ADD_ENCRYPTION_KEY, arg) != 0) {
+ PLOG(ERROR) << "Failed to install fscrypt key to " << mountpoint;
+ return false;
+ }
+
+ return true;
+}
+
bool installKey(const std::string& mountpoint, const EncryptionOptions& options,
const KeyBuffer& key, EncryptionPolicy* policy) {
policy->options = options;
@@ -240,33 +294,24 @@
return false;
}
- if (options.use_hw_wrapped_key) arg->flags |= FSCRYPT_ADD_KEY_FLAG_WRAPPED;
- // Provide the raw key.
arg->raw_size = key.size();
memcpy(arg->raw, key.data(), key.size());
- android::base::unique_fd fd(open(mountpoint.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC));
- if (fd == -1) {
- PLOG(ERROR) << "Failed to open " << mountpoint << " to install key";
- return false;
- }
-
- if (ioctl(fd, FS_IOC_ADD_ENCRYPTION_KEY, arg) != 0) {
- PLOG(ERROR) << "Failed to install fscrypt key to " << mountpoint;
- return false;
- }
+ if (!installFsKeyringKey(mountpoint, options, arg)) return false;
if (arg->key_spec.type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) {
// Retrieve the key identifier that the kernel computed.
policy->key_raw_ref =
std::string((char*)arg->key_spec.u.identifier, FSCRYPT_KEY_IDENTIFIER_SIZE);
}
- LOG(DEBUG) << "Installed fscrypt key with ref " << keyrefstring(policy->key_raw_ref) << " to "
- << mountpoint;
+ std::string ref = keyrefstring(policy->key_raw_ref);
+ LOG(DEBUG) << "Installed fscrypt key with ref " << ref << " to " << mountpoint;
+
+ if (!installProvisioningKey(key, ref, arg->key_spec)) return false;
return true;
}
-// Remove an encryption key from the legacy global session keyring.
+// Remove an encryption key of type "logon" from the global session keyring.
static bool evictKeyLegacy(const std::string& raw_ref) {
key_serial_t device_keyring;
if (!fscryptKeyring(&device_keyring)) return false;
@@ -289,6 +334,26 @@
return success;
}
+static bool evictProvisioningKey(const std::string& ref) {
+ key_serial_t device_keyring;
+ if (!fscryptKeyring(&device_keyring)) {
+ return false;
+ }
+
+ auto key_serial = keyctl_search(device_keyring, "fscrypt-provisioning", ref.c_str(), 0);
+ if (key_serial == -1 && errno != ENOKEY) {
+ PLOG(ERROR) << "Error searching session keyring for fscrypt-provisioning key for " << ref;
+ return false;
+ }
+
+ if (key_serial != -1 && keyctl_unlink(key_serial, device_keyring) != 0) {
+ PLOG(ERROR) << "Failed to unlink fscrypt-provisioning key for " << ref
+ << " from session keyring";
+ return false;
+ }
+ return true;
+}
+
bool evictKey(const std::string& mountpoint, const EncryptionPolicy& policy) {
if (policy.options.version == 1 && !isFsKeyringSupported()) {
return evictKeyLegacy(policy.key_raw_ref);
@@ -322,6 +387,8 @@
LOG(ERROR) << "Files still open after removing key with ref " << ref
<< ". These files were not locked!";
}
+
+ if (!evictProvisioningKey(ref)) return false;
return true;
}
@@ -343,5 +410,31 @@
return true;
}
+bool reloadKeyFromSessionKeyring(const std::string& mountpoint, const EncryptionPolicy& policy) {
+ key_serial_t device_keyring;
+ if (!fscryptKeyring(&device_keyring)) {
+ return false;
+ }
+
+ std::string ref = keyrefstring(policy.key_raw_ref);
+ auto key_serial = keyctl_search(device_keyring, "fscrypt-provisioning", ref.c_str(), 0);
+ if (key_serial == -1) {
+ PLOG(ERROR) << "Failed to find fscrypt-provisioning key for " << ref
+ << " in session keyring";
+ return false;
+ }
+
+ LOG(DEBUG) << "Installing fscrypt-provisioning key for " << ref << " back into " << mountpoint
+ << " fs-keyring";
+
+ struct fscrypt_add_key_arg arg;
+ memset(&arg, 0, sizeof(arg));
+ if (!buildKeySpecifier(&arg.key_spec, policy)) return false;
+ arg.key_id = key_serial;
+ if (!installFsKeyringKey(mountpoint, policy.options, &arg)) return false;
+
+ return true;
+}
+
} // namespace vold
} // namespace android