Trust CompOs-signed artifacts
If the current artifacts are missing or invalid, and if we have
pending CompOs artifacts, then attempt to use them. This includes
verifying the signatures and adding them to fs-verity if need be.
This is largely a proposal in the form of a CL. Note specifically the
definition of what a signature file looks like
(compos_signature.proto, VerityUtils.cpp).
I rationalised the way we handle multiple certificate subjects because
it was starting to get messy & confusing.
Apart from various refactorings, the significant changes remain behind
an if (false). It is currently largely untestable (we don't have
anything to produce signatures) and there's a couple more CLs to come,
but I think this is a big enough CL as it stands.
Bug: 190166662
Test: Create pending directory, see it deleted.
Test: Create valid pending directory, it gets renamed, fails verification
Test: Invalid signature file is rejected
Test: Presubmit
Change-Id: I20ef65f3c382bcfd5db8747e73fc0148a4b978e9
diff --git a/ondevice-signing/CertUtils.cpp b/ondevice-signing/CertUtils.cpp
index ce2b0fd..acc11e4 100644
--- a/ondevice-signing/CertUtils.cpp
+++ b/ondevice-signing/CertUtils.cpp
@@ -31,8 +31,10 @@
#include "KeyConstants.h"
-const char kRootCommonName[] = "ODS";
+// Common properties for all of our certificates.
constexpr int kCertLifetimeSeconds = 10 * 365 * 24 * 60 * 60;
+const char* const kIssuerCountry = "US";
+const char* const kIssuerOrg = "Android";
using android::base::ErrnoError;
using android::base::Error;
@@ -105,7 +107,7 @@
(const uint8_t*)signature.c_str(), signature.length(), rsaKey->get());
if (!success) {
- return Error() << "Failed to verify signature.";
+ return Error() << "Failed to verify signature";
}
return {};
}
@@ -126,7 +128,7 @@
}
static Result<void> createCertificate(
- const char* commonName, const std::vector<uint8_t>& publicKey,
+ const CertSubject& subject, const std::vector<uint8_t>& publicKey,
const std::function<android::base::Result<std::string>(const std::string&)>& signFunction,
const std::optional<std::string>& issuerCertPath, const std::string& path) {
@@ -141,7 +143,7 @@
X509_set_version(x509.get(), 2);
X509_gmtime_adj(X509_get_notBefore(x509.get()), 0);
X509_gmtime_adj(X509_get_notAfter(x509.get()), kCertLifetimeSeconds);
- ASN1_INTEGER_set(X509_get_serialNumber(x509.get()), selfSigned ? 1 : 2);
+ ASN1_INTEGER_set(X509_get_serialNumber(x509.get()), subject.serialNumber);
bssl::UniquePtr<X509_ALGOR> algor(X509_ALGOR_new());
if (!algor ||
@@ -164,9 +166,9 @@
if (!subjectName) {
return Error() << "Unable to get x509 subject name";
}
- addNameEntry(subjectName, "C", "US");
- addNameEntry(subjectName, "O", "Android");
- addNameEntry(subjectName, "CN", commonName);
+ addNameEntry(subjectName, "C", kIssuerCountry);
+ addNameEntry(subjectName, "O", kIssuerOrg);
+ addNameEntry(subjectName, "CN", subject.commonName);
if (selfSigned) {
if (!X509_set_issuer_name(x509.get(), subjectName)) {
@@ -177,9 +179,9 @@
if (!issuerName) {
return Error() << "Unable to get x509 issuer name";
}
- addNameEntry(issuerName, "C", "US");
- addNameEntry(issuerName, "O", "Android");
- addNameEntry(issuerName, "CN", kRootCommonName);
+ addNameEntry(issuerName, "C", kIssuerCountry);
+ addNameEntry(issuerName, "O", kIssuerOrg);
+ addNameEntry(issuerName, "CN", kRootSubject.commonName);
}
// Beware: context contains a pointer to issuerCert, so we need to keep it alive.
@@ -239,14 +241,14 @@
const std::vector<uint8_t>& publicKey,
const std::function<Result<std::string>(const std::string&)>& signFunction,
const std::string& path) {
- return createCertificate(kRootCommonName, publicKey, signFunction, {}, path);
+ return createCertificate(kRootSubject, publicKey, signFunction, {}, path);
}
android::base::Result<void> createLeafCertificate(
- const char* commonName, const std::vector<uint8_t>& publicKey,
+ const CertSubject& subject, const std::vector<uint8_t>& publicKey,
const std::function<android::base::Result<std::string>(const std::string&)>& signFunction,
const std::string& issuerCertPath, const std::string& path) {
- return createCertificate(commonName, publicKey, signFunction, issuerCertPath, path);
+ return createCertificate(subject, publicKey, signFunction, issuerCertPath, path);
}
Result<std::vector<uint8_t>> extractPublicKey(EVP_PKEY* pkey) {
@@ -340,7 +342,8 @@
return cert_info;
}
-Result<std::vector<uint8_t>> createPkcs7(const std::vector<uint8_t>& signed_digest) {
+Result<std::vector<uint8_t>> createPkcs7(const std::vector<uint8_t>& signed_digest,
+ const CertSubject& signer) {
CBB out, outer_seq, wrapped_seq, seq, digest_algos_set, digest_algo, null;
CBB content_info, issuer_and_serial, signer_infos, signer_info, sign_algo, signature;
uint8_t *pkcs7_data, *name_der;
@@ -353,13 +356,14 @@
return Error() << "Unable to get x509 subject name";
}
X509_NAME_add_entry_by_txt(name, "C", MBSTRING_ASC,
- reinterpret_cast<const unsigned char*>("US"), -1, -1, 0);
+ reinterpret_cast<const unsigned char*>(kIssuerCountry), -1, -1, 0);
X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC,
- reinterpret_cast<const unsigned char*>("Android"), -1, -1, 0);
+ reinterpret_cast<const unsigned char*>(kIssuerOrg), -1, -1, 0);
X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC,
- reinterpret_cast<const unsigned char*>("ODS"), -1, -1, 0);
+ reinterpret_cast<const unsigned char*>(signer.commonName), -1, -1,
+ 0);
- BN_set_word(serial, 1);
+ BN_set_word(serial, signer.serialNumber);
name_der_len = i2d_X509_NAME(name, &name_der);
CBB_init(&out, 1024);