Add code to support keystore certificate post processing.
Adds the AIDL needed for the post processing service.
Also adds the client which would communicate via the post processing
service. The call to post processing depends on the presence of a
boolean system property which is set during build time.
Bug: 361877215
Test: manual testing
Change-Id: Icfc11d0d83187e036902ed1060038fc627512879
diff --git a/keystore2/postprocessor_client/Android.bp b/keystore2/postprocessor_client/Android.bp
new file mode 100644
index 0000000..7f0194a
--- /dev/null
+++ b/keystore2/postprocessor_client/Android.bp
@@ -0,0 +1,47 @@
+//
+// Copyright 2024, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package {
+ // See: http://go/android-license-faq
+ // A large-scale-change added 'default_applicable_licenses' to import
+ // all of the 'license_kinds' from "system_security_license"
+ // to get the below license kinds:
+ // SPDX-license-identifier-Apache-2.0
+ default_applicable_licenses: ["system_security_license"],
+}
+
+rust_defaults {
+ name: "libpostprocessor_client_defaults",
+ crate_name: "postprocessor_client",
+ srcs: ["src/lib.rs"],
+ rustlibs: [
+ "android.security.postprocessor-rust",
+ "libanyhow",
+ "libbinder_rs",
+ "liblog_rust",
+ "libmessage_macro",
+ "libthiserror",
+ ],
+ defaults: [
+ "keymint_use_latest_hal_aidl_rust",
+ ],
+}
+
+rust_library {
+ name: "libpostprocessor_client",
+ defaults: [
+ "libpostprocessor_client_defaults",
+ ],
+}
diff --git a/keystore2/postprocessor_client/src/lib.rs b/keystore2/postprocessor_client/src/lib.rs
new file mode 100644
index 0000000..8b347f9
--- /dev/null
+++ b/keystore2/postprocessor_client/src/lib.rs
@@ -0,0 +1,109 @@
+// Copyright 2024, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Helper wrapper around PostProcessor interface.
+
+use android_hardware_security_keymint::aidl::android::hardware::security::keymint::Certificate::Certificate;
+use android_security_postprocessor::aidl::android::security::postprocessor::{
+ CertificateChain::CertificateChain,
+ IKeystoreCertificatePostProcessor::IKeystoreCertificatePostProcessor,
+};
+use anyhow::{Context, Result};
+use binder::{StatusCode, Strong};
+use log::{error, info, warn};
+use message_macro::source_location_msg;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::mpsc;
+use std::thread;
+use std::time::Duration;
+
+/// Errors occurred during the interaction with Certificate Processor
+#[derive(Debug, Clone, Copy, thiserror::Error, PartialEq, Eq)]
+#[error("Binder transaction error {0:?}")]
+pub struct Error(pub StatusCode);
+
+static CERT_PROCESSOR_FAILURE: AtomicBool = AtomicBool::new(false);
+
+fn send_certificate_chain_to_processor(
+ attestation_chain: CertificateChain,
+) -> Result<CertificateChain> {
+ let cert_processing_server: Strong<dyn IKeystoreCertificatePostProcessor> = wait_for_interface(
+ "rkp_cert_processor.service".to_string(),
+ )
+ .context(source_location_msg!("While trying to connect to the post processor service."))?;
+ cert_processing_server
+ .processKeystoreCertificates(&attestation_chain)
+ .context(source_location_msg!("While trying to post process certificates."))
+}
+
+/// Processes the keystore certificates after the certificate chain has been generated by Keystore.
+/// More details about this function provided in IKeystoreCertificatePostProcessor.aidl
+pub fn process_certificate_chain(
+ mut certificates: Vec<Certificate>,
+ attestation_certs: Vec<u8>,
+) -> Vec<Certificate> {
+ // If no certificates are provided from keymint, return the original chain.
+ if certificates.is_empty() {
+ error!("No leaf certificate provided.");
+ return vec![Certificate { encodedCertificate: attestation_certs }];
+ }
+
+ if certificates.len() > 1 {
+ warn!("dropping {} unexpected extra certificates after the leaf", certificates.len() - 1);
+ }
+
+ let attestation_chain = CertificateChain {
+ leafCertificate: certificates[0].encodedCertificate.clone(),
+ remainingChain: attestation_certs.clone(),
+ };
+ let result = send_certificate_chain_to_processor(attestation_chain);
+ match result {
+ Ok(certificate_chain) => {
+ info!("Post processing successful. Replacing certificates.");
+ vec![
+ Certificate { encodedCertificate: certificate_chain.leafCertificate },
+ Certificate { encodedCertificate: certificate_chain.remainingChain },
+ ]
+ }
+ Err(err) => {
+ error!("Failed to replace certificates ({err:#?}), falling back to original chain.");
+ certificates.push(Certificate { encodedCertificate: attestation_certs });
+ certificates
+ }
+ }
+}
+
+fn wait_for_interface(
+ service_name: String,
+) -> Result<Strong<dyn IKeystoreCertificatePostProcessor>> {
+ if CERT_PROCESSOR_FAILURE.load(Ordering::Relaxed) {
+ return Err(Error(StatusCode::INVALID_OPERATION).into());
+ }
+ let (sender, receiver) = mpsc::channel();
+ let _t = thread::spawn(move || {
+ if let Err(e) = sender.send(binder::wait_for_interface(&service_name)) {
+ error!("failed to send result of wait_for_interface({service_name}), likely due to timeout: {e:?}");
+ }
+ });
+
+ match receiver.recv_timeout(Duration::from_secs(5)) {
+ Ok(service_binder) => Ok(service_binder?),
+ Err(e) => {
+ error!("Timed out while connecting to post processor service: {e:#?}");
+ // Cert processor has failed. Retry only after reboot.
+ CERT_PROCESSOR_FAILURE.store(true, Ordering::Relaxed);
+ Err(e.into())
+ }
+ }
+}