Move install to separate module
Build libinstall as a shared library. Also drop the dependency on the
global variables in common.h.
Test: unit tests pass, sideload an OTA
Change-Id: I30a20047768ce00689fc0e7851c1c5d712a365a0
diff --git a/install/verifier.cpp b/install/verifier.cpp
new file mode 100644
index 0000000..6ba1d77
--- /dev/null
+++ b/install/verifier.cpp
@@ -0,0 +1,468 @@
+/*
+ * Copyright (C) 2008 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.
+ */
+
+#include "install/verifier.h"
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <vector>
+
+#include <android-base/logging.h>
+#include <openssl/bio.h>
+#include <openssl/bn.h>
+#include <openssl/ecdsa.h>
+#include <openssl/evp.h>
+#include <openssl/obj_mac.h>
+#include <openssl/pem.h>
+#include <openssl/rsa.h>
+#include <ziparchive/zip_archive.h>
+
+#include "otautil/print_sha1.h"
+#include "private/asn1_decoder.h"
+
+/*
+ * Simple version of PKCS#7 SignedData extraction. This extracts the
+ * signature OCTET STRING to be used for signature verification.
+ *
+ * For full details, see http://www.ietf.org/rfc/rfc3852.txt
+ *
+ * The PKCS#7 structure looks like:
+ *
+ * SEQUENCE (ContentInfo)
+ * OID (ContentType)
+ * [0] (content)
+ * SEQUENCE (SignedData)
+ * INTEGER (version CMSVersion)
+ * SET (DigestAlgorithmIdentifiers)
+ * SEQUENCE (EncapsulatedContentInfo)
+ * [0] (CertificateSet OPTIONAL)
+ * [1] (RevocationInfoChoices OPTIONAL)
+ * SET (SignerInfos)
+ * SEQUENCE (SignerInfo)
+ * INTEGER (CMSVersion)
+ * SEQUENCE (SignerIdentifier)
+ * SEQUENCE (DigestAlgorithmIdentifier)
+ * SEQUENCE (SignatureAlgorithmIdentifier)
+ * OCTET STRING (SignatureValue)
+ */
+static bool read_pkcs7(const uint8_t* pkcs7_der, size_t pkcs7_der_len,
+ std::vector<uint8_t>* sig_der) {
+ CHECK(sig_der != nullptr);
+ sig_der->clear();
+
+ asn1_context ctx(pkcs7_der, pkcs7_der_len);
+
+ std::unique_ptr<asn1_context> pkcs7_seq(ctx.asn1_sequence_get());
+ if (pkcs7_seq == nullptr || !pkcs7_seq->asn1_sequence_next()) {
+ return false;
+ }
+
+ std::unique_ptr<asn1_context> signed_data_app(pkcs7_seq->asn1_constructed_get());
+ if (signed_data_app == nullptr) {
+ return false;
+ }
+
+ std::unique_ptr<asn1_context> signed_data_seq(signed_data_app->asn1_sequence_get());
+ if (signed_data_seq == nullptr || !signed_data_seq->asn1_sequence_next() ||
+ !signed_data_seq->asn1_sequence_next() || !signed_data_seq->asn1_sequence_next() ||
+ !signed_data_seq->asn1_constructed_skip_all()) {
+ return false;
+ }
+
+ std::unique_ptr<asn1_context> sig_set(signed_data_seq->asn1_set_get());
+ if (sig_set == nullptr) {
+ return false;
+ }
+
+ std::unique_ptr<asn1_context> sig_seq(sig_set->asn1_sequence_get());
+ if (sig_seq == nullptr || !sig_seq->asn1_sequence_next() || !sig_seq->asn1_sequence_next() ||
+ !sig_seq->asn1_sequence_next() || !sig_seq->asn1_sequence_next()) {
+ return false;
+ }
+
+ const uint8_t* sig_der_ptr;
+ size_t sig_der_length;
+ if (!sig_seq->asn1_octet_string_get(&sig_der_ptr, &sig_der_length)) {
+ return false;
+ }
+
+ sig_der->resize(sig_der_length);
+ std::copy(sig_der_ptr, sig_der_ptr + sig_der_length, sig_der->begin());
+ return true;
+}
+
+int verify_file(VerifierInterface* package, const std::vector<Certificate>& keys) {
+ CHECK(package);
+ package->SetProgress(0.0);
+
+ // An archive with a whole-file signature will end in six bytes:
+ //
+ // (2-byte signature start) $ff $ff (2-byte comment size)
+ //
+ // (As far as the ZIP format is concerned, these are part of the archive comment.) We start by
+ // reading this footer, this tells us how far back from the end we have to start reading to find
+ // the whole comment.
+
+#define FOOTER_SIZE 6
+ uint64_t length = package->GetPackageSize();
+
+ if (length < FOOTER_SIZE) {
+ LOG(ERROR) << "not big enough to contain footer";
+ return VERIFY_FAILURE;
+ }
+
+ uint8_t footer[FOOTER_SIZE];
+ if (!package->ReadFullyAtOffset(footer, FOOTER_SIZE, length - FOOTER_SIZE)) {
+ LOG(ERROR) << "Failed to read footer";
+ return VERIFY_FAILURE;
+ }
+
+ if (footer[2] != 0xff || footer[3] != 0xff) {
+ LOG(ERROR) << "footer is wrong";
+ return VERIFY_FAILURE;
+ }
+
+ size_t comment_size = footer[4] + (footer[5] << 8);
+ size_t signature_start = footer[0] + (footer[1] << 8);
+ LOG(INFO) << "comment is " << comment_size << " bytes; signature is " << signature_start
+ << " bytes from end";
+
+ if (signature_start > comment_size) {
+ LOG(ERROR) << "signature start: " << signature_start
+ << " is larger than comment size: " << comment_size;
+ return VERIFY_FAILURE;
+ }
+
+ if (signature_start <= FOOTER_SIZE) {
+ LOG(ERROR) << "Signature start is in the footer";
+ return VERIFY_FAILURE;
+ }
+
+#define EOCD_HEADER_SIZE 22
+
+ // The end-of-central-directory record is 22 bytes plus any comment length.
+ size_t eocd_size = comment_size + EOCD_HEADER_SIZE;
+
+ if (length < eocd_size) {
+ LOG(ERROR) << "not big enough to contain EOCD";
+ return VERIFY_FAILURE;
+ }
+
+ // Determine how much of the file is covered by the signature. This is everything except the
+ // signature data and length, which includes all of the EOCD except for the comment length field
+ // (2 bytes) and the comment data.
+ uint64_t signed_len = length - eocd_size + EOCD_HEADER_SIZE - 2;
+
+ uint8_t eocd[eocd_size];
+ if (!package->ReadFullyAtOffset(eocd, eocd_size, length - eocd_size)) {
+ LOG(ERROR) << "Failed to read EOCD of " << eocd_size << " bytes";
+ return VERIFY_FAILURE;
+ }
+
+ // If this is really is the EOCD record, it will begin with the magic number $50 $4b $05 $06.
+ if (eocd[0] != 0x50 || eocd[1] != 0x4b || eocd[2] != 0x05 || eocd[3] != 0x06) {
+ LOG(ERROR) << "signature length doesn't match EOCD marker";
+ return VERIFY_FAILURE;
+ }
+
+ for (size_t i = 4; i < eocd_size - 3; ++i) {
+ if (eocd[i] == 0x50 && eocd[i + 1] == 0x4b && eocd[i + 2] == 0x05 && eocd[i + 3] == 0x06) {
+ // If the sequence $50 $4b $05 $06 appears anywhere after the real one, libziparchive will
+ // find the later (wrong) one, which could be exploitable. Fail the verification if this
+ // sequence occurs anywhere after the real one.
+ LOG(ERROR) << "EOCD marker occurs after start of EOCD";
+ return VERIFY_FAILURE;
+ }
+ }
+
+ bool need_sha1 = false;
+ bool need_sha256 = false;
+ for (const auto& key : keys) {
+ switch (key.hash_len) {
+ case SHA_DIGEST_LENGTH:
+ need_sha1 = true;
+ break;
+ case SHA256_DIGEST_LENGTH:
+ need_sha256 = true;
+ break;
+ }
+ }
+
+ SHA_CTX sha1_ctx;
+ SHA256_CTX sha256_ctx;
+ SHA1_Init(&sha1_ctx);
+ SHA256_Init(&sha256_ctx);
+
+ std::vector<HasherUpdateCallback> hashers;
+ if (need_sha1) {
+ hashers.emplace_back(
+ std::bind(&SHA1_Update, &sha1_ctx, std::placeholders::_1, std::placeholders::_2));
+ }
+ if (need_sha256) {
+ hashers.emplace_back(
+ std::bind(&SHA256_Update, &sha256_ctx, std::placeholders::_1, std::placeholders::_2));
+ }
+
+ double frac = -1.0;
+ uint64_t so_far = 0;
+ while (so_far < signed_len) {
+ // On a Nexus 5X, experiment showed 16MiB beat 1MiB by 6% faster for a 1196MiB full OTA and
+ // 60% for an 89MiB incremental OTA. http://b/28135231.
+ uint64_t read_size = std::min<uint64_t>(signed_len - so_far, 16 * MiB);
+ package->UpdateHashAtOffset(hashers, so_far, read_size);
+ so_far += read_size;
+
+ double f = so_far / static_cast<double>(signed_len);
+ if (f > frac + 0.02 || read_size == so_far) {
+ package->SetProgress(f);
+ frac = f;
+ }
+ }
+
+ uint8_t sha1[SHA_DIGEST_LENGTH];
+ SHA1_Final(sha1, &sha1_ctx);
+ uint8_t sha256[SHA256_DIGEST_LENGTH];
+ SHA256_Final(sha256, &sha256_ctx);
+
+ const uint8_t* signature = eocd + eocd_size - signature_start;
+ size_t signature_size = signature_start - FOOTER_SIZE;
+
+ LOG(INFO) << "signature (offset: " << std::hex << (length - signature_start)
+ << ", length: " << signature_size << "): " << print_hex(signature, signature_size);
+
+ std::vector<uint8_t> sig_der;
+ if (!read_pkcs7(signature, signature_size, &sig_der)) {
+ LOG(ERROR) << "Could not find signature DER block";
+ return VERIFY_FAILURE;
+ }
+
+ // Check to make sure at least one of the keys matches the signature. Since any key can match,
+ // we need to try each before determining a verification failure has happened.
+ size_t i = 0;
+ for (const auto& key : keys) {
+ const uint8_t* hash;
+ int hash_nid;
+ switch (key.hash_len) {
+ case SHA_DIGEST_LENGTH:
+ hash = sha1;
+ hash_nid = NID_sha1;
+ break;
+ case SHA256_DIGEST_LENGTH:
+ hash = sha256;
+ hash_nid = NID_sha256;
+ break;
+ default:
+ continue;
+ }
+
+ // The 6 bytes is the "(signature_start) $ff $ff (comment_size)" that the signing tool appends
+ // after the signature itself.
+ if (key.key_type == Certificate::KEY_TYPE_RSA) {
+ if (!RSA_verify(hash_nid, hash, key.hash_len, sig_der.data(), sig_der.size(),
+ key.rsa.get())) {
+ LOG(INFO) << "failed to verify against RSA key " << i;
+ continue;
+ }
+
+ LOG(INFO) << "whole-file signature verified against RSA key " << i;
+ return VERIFY_SUCCESS;
+ } else if (key.key_type == Certificate::KEY_TYPE_EC && key.hash_len == SHA256_DIGEST_LENGTH) {
+ if (!ECDSA_verify(0, hash, key.hash_len, sig_der.data(), sig_der.size(), key.ec.get())) {
+ LOG(INFO) << "failed to verify against EC key " << i;
+ continue;
+ }
+
+ LOG(INFO) << "whole-file signature verified against EC key " << i;
+ return VERIFY_SUCCESS;
+ } else {
+ LOG(INFO) << "Unknown key type " << key.key_type;
+ }
+ i++;
+ }
+
+ if (need_sha1) {
+ LOG(INFO) << "SHA-1 digest: " << print_hex(sha1, SHA_DIGEST_LENGTH);
+ }
+ if (need_sha256) {
+ LOG(INFO) << "SHA-256 digest: " << print_hex(sha256, SHA256_DIGEST_LENGTH);
+ }
+ LOG(ERROR) << "failed to verify whole-file signature";
+ return VERIFY_FAILURE;
+}
+
+static std::vector<Certificate> IterateZipEntriesAndSearchForKeys(const ZipArchiveHandle& handle) {
+ void* cookie;
+ ZipString suffix("x509.pem");
+ int32_t iter_status = StartIteration(handle, &cookie, nullptr, &suffix);
+ if (iter_status != 0) {
+ LOG(ERROR) << "Failed to iterate over entries in the certificate zipfile: "
+ << ErrorCodeString(iter_status);
+ return {};
+ }
+
+ std::vector<Certificate> result;
+
+ ZipString name;
+ ZipEntry entry;
+ while ((iter_status = Next(cookie, &entry, &name)) == 0) {
+ std::vector<uint8_t> pem_content(entry.uncompressed_length);
+ if (int32_t extract_status =
+ ExtractToMemory(handle, &entry, pem_content.data(), pem_content.size());
+ extract_status != 0) {
+ LOG(ERROR) << "Failed to extract " << std::string(name.name, name.name + name.name_length);
+ return {};
+ }
+
+ Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+ // Aborts the parsing if we fail to load one of the key file.
+ if (!LoadCertificateFromBuffer(pem_content, &cert)) {
+ LOG(ERROR) << "Failed to load keys from "
+ << std::string(name.name, name.name + name.name_length);
+ return {};
+ }
+
+ result.emplace_back(std::move(cert));
+ }
+
+ if (iter_status != -1) {
+ LOG(ERROR) << "Error while iterating over zip entries: " << ErrorCodeString(iter_status);
+ return {};
+ }
+
+ return result;
+}
+
+std::vector<Certificate> LoadKeysFromZipfile(const std::string& zip_name) {
+ ZipArchiveHandle handle;
+ if (int32_t open_status = OpenArchive(zip_name.c_str(), &handle); open_status != 0) {
+ LOG(ERROR) << "Failed to open " << zip_name << ": " << ErrorCodeString(open_status);
+ return {};
+ }
+
+ std::vector<Certificate> result = IterateZipEntriesAndSearchForKeys(handle);
+ CloseArchive(handle);
+ return result;
+}
+
+bool CheckRSAKey(const std::unique_ptr<RSA, RSADeleter>& rsa) {
+ if (!rsa) {
+ return false;
+ }
+
+ const BIGNUM* out_n;
+ const BIGNUM* out_e;
+ RSA_get0_key(rsa.get(), &out_n, &out_e, nullptr /* private exponent */);
+ auto modulus_bits = BN_num_bits(out_n);
+ if (modulus_bits != 2048 && modulus_bits != 4096) {
+ LOG(ERROR) << "Modulus should be 2048 or 4096 bits long, actual: " << modulus_bits;
+ return false;
+ }
+
+ BN_ULONG exponent = BN_get_word(out_e);
+ if (exponent != 3 && exponent != 65537) {
+ LOG(ERROR) << "Public exponent should be 3 or 65537, actual: " << exponent;
+ return false;
+ }
+
+ return true;
+}
+
+bool CheckECKey(const std::unique_ptr<EC_KEY, ECKEYDeleter>& ec_key) {
+ if (!ec_key) {
+ return false;
+ }
+
+ const EC_GROUP* ec_group = EC_KEY_get0_group(ec_key.get());
+ if (!ec_group) {
+ LOG(ERROR) << "Failed to get the ec_group from the ec_key";
+ return false;
+ }
+ auto degree = EC_GROUP_get_degree(ec_group);
+ if (degree != 256) {
+ LOG(ERROR) << "Field size of the ec key should be 256 bits long, actual: " << degree;
+ return false;
+ }
+
+ return true;
+}
+
+bool LoadCertificateFromBuffer(const std::vector<uint8_t>& pem_content, Certificate* cert) {
+ std::unique_ptr<BIO, decltype(&BIO_free)> content(
+ BIO_new_mem_buf(pem_content.data(), pem_content.size()), BIO_free);
+
+ std::unique_ptr<X509, decltype(&X509_free)> x509(
+ PEM_read_bio_X509(content.get(), nullptr, nullptr, nullptr), X509_free);
+ if (!x509) {
+ LOG(ERROR) << "Failed to read x509 certificate";
+ return false;
+ }
+
+ int nid = X509_get_signature_nid(x509.get());
+ switch (nid) {
+ // SignApk has historically accepted md5WithRSA certificates, but treated them as
+ // sha1WithRSA anyway. Continue to do so for backwards compatibility.
+ case NID_md5WithRSA:
+ case NID_md5WithRSAEncryption:
+ case NID_sha1WithRSA:
+ case NID_sha1WithRSAEncryption:
+ cert->hash_len = SHA_DIGEST_LENGTH;
+ break;
+ case NID_sha256WithRSAEncryption:
+ case NID_ecdsa_with_SHA256:
+ cert->hash_len = SHA256_DIGEST_LENGTH;
+ break;
+ default:
+ LOG(ERROR) << "Unrecognized signature nid " << OBJ_nid2ln(nid);
+ return false;
+ }
+
+ std::unique_ptr<EVP_PKEY, decltype(&EVP_PKEY_free)> public_key(X509_get_pubkey(x509.get()),
+ EVP_PKEY_free);
+ if (!public_key) {
+ LOG(ERROR) << "Failed to extract the public key from x509 certificate";
+ return false;
+ }
+
+ int key_type = EVP_PKEY_id(public_key.get());
+ if (key_type == EVP_PKEY_RSA) {
+ cert->key_type = Certificate::KEY_TYPE_RSA;
+ cert->ec.reset();
+ cert->rsa.reset(EVP_PKEY_get1_RSA(public_key.get()));
+ if (!cert->rsa || !CheckRSAKey(cert->rsa)) {
+ LOG(ERROR) << "Failed to validate the rsa key info from public key";
+ return false;
+ }
+ } else if (key_type == EVP_PKEY_EC) {
+ cert->key_type = Certificate::KEY_TYPE_EC;
+ cert->rsa.reset();
+ cert->ec.reset(EVP_PKEY_get1_EC_KEY(public_key.get()));
+ if (!cert->ec || !CheckECKey(cert->ec)) {
+ LOG(ERROR) << "Failed to validate the ec key info from the public key";
+ return false;
+ }
+ } else {
+ LOG(ERROR) << "Unrecognized public key type " << OBJ_nid2ln(key_type);
+ return false;
+ }
+
+ return true;
+}