diff options
Diffstat (limited to 'install/verifier.cpp')
| -rw-r--r-- | install/verifier.cpp | 472 |
1 files changed, 0 insertions, 472 deletions
diff --git a/install/verifier.cpp b/install/verifier.cpp deleted file mode 100644 index 3f0260138..000000000 --- a/install/verifier.cpp +++ /dev/null @@ -1,472 +0,0 @@ -/* - * 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; - int32_t iter_status = StartIteration(handle, &cookie, "", "x509.pem"); - if (iter_status != 0) { - LOG(ERROR) << "Failed to iterate over entries in the certificate zipfile: " - << ErrorCodeString(iter_status); - return {}; - } - - std::vector<Certificate> result; - - std::string_view name; - ZipEntry64 entry; - while ((iter_status = Next(cookie, &entry, &name)) == 0) { - if (entry.uncompressed_length > std::numeric_limits<size_t>::max()) { - LOG(ERROR) << "Failed to extract " << name - << " because's uncompressed size exceeds size of address space. " - << entry.uncompressed_length; - return {}; - } - 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 " << name; - 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 " << name; - 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; -} |