diff options
Diffstat (limited to 'verifier.cpp')
| -rw-r--r-- | verifier.cpp | 339 |
1 files changed, 166 insertions, 173 deletions
diff --git a/verifier.cpp b/verifier.cpp index 82454867b..582c498fb 100644 --- a/verifier.cpp +++ b/verifier.cpp @@ -21,6 +21,7 @@ #include <stdlib.h> #include <string.h> +#include <functional> #include <algorithm> #include <memory> @@ -108,207 +109,199 @@ static bool read_pkcs7(uint8_t* pkcs7_der, size_t pkcs7_der_len, uint8_t** sig_d return *sig_der != NULL; } -// Look for an RSA signature embedded in the .ZIP file comment given -// the path to the zip. Verify it matches one of the given public -// keys. -// -// Return VERIFY_SUCCESS, VERIFY_FAILURE (if any error is encountered -// or no key matches the signature). - -int verify_file(unsigned char* addr, size_t length, - const std::vector<Certificate>& keys) { - ui->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. +/* + * Looks for an RSA signature embedded in the .ZIP file comment given the path to the zip. Verifies + * that it matches one of the given public keys. A callback function can be optionally provided for + * posting the progress. + * + * Returns VERIFY_SUCCESS or VERIFY_FAILURE (if any error is encountered or no key matches the + * signature). + */ +int verify_file(unsigned char* addr, size_t length, const std::vector<Certificate>& keys, + const std::function<void(float)>& set_progress) { + if (set_progress) { + set_progress(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 - if (length < FOOTER_SIZE) { - LOG(ERROR) << "not big enough to contain footer"; - return VERIFY_FAILURE; - } + if (length < FOOTER_SIZE) { + LOG(ERROR) << "not big enough to contain footer"; + return VERIFY_FAILURE; + } - unsigned char* footer = addr + length - FOOTER_SIZE; + unsigned char* footer = addr + length - FOOTER_SIZE; - if (footer[2] != 0xff || footer[3] != 0xff) { - LOG(ERROR) << "footer is wrong"; - 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"; + 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 > 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; - } + 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; + // 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; - } + 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. - size_t signed_len = length - eocd_size + EOCD_HEADER_SIZE - 2; + // 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. + size_t signed_len = length - eocd_size + EOCD_HEADER_SIZE - 2; - unsigned char* eocd = addr + length - eocd_size; + unsigned char* eocd = addr + length - eocd_size; - // 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; - } + // 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 verification if - // this sequence occurs anywhere after the real one. - LOG(ERROR) << "EOCD marker occurs after start of EOCD"; - 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; - } + 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); - - double frac = -1.0; - size_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. - size_t size = std::min(signed_len - so_far, 16 * MiB); - - if (need_sha1) SHA1_Update(&sha1_ctx, addr + so_far, size); - if (need_sha256) SHA256_Update(&sha256_ctx, addr + so_far, size); - so_far += size; - - double f = so_far / (double)signed_len; - if (f > frac + 0.02 || size == so_far) { - ui->SetProgress(f); - frac = f; - } + SHA_CTX sha1_ctx; + SHA256_CTX sha256_ctx; + SHA1_Init(&sha1_ctx); + SHA256_Init(&sha256_ctx); + + double frac = -1.0; + size_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. + size_t size = std::min(signed_len - so_far, 16 * MiB); + + if (need_sha1) SHA1_Update(&sha1_ctx, addr + so_far, size); + if (need_sha256) SHA256_Update(&sha256_ctx, addr + so_far, size); + so_far += size; + + if (set_progress) { + double f = so_far / (double)signed_len; + if (f > frac + 0.02 || size == so_far) { + set_progress(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); - - uint8_t* sig_der = nullptr; - size_t sig_der_length = 0; - - 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); + uint8_t sha1[SHA_DIGEST_LENGTH]; + SHA1_Final(sha1, &sha1_ctx); + uint8_t sha256[SHA256_DIGEST_LENGTH]; + SHA256_Final(sha256, &sha256_ctx); - if (!read_pkcs7(signature, signature_size, &sig_der, &sig_der_length)) { - LOG(ERROR) << "Could not find signature DER block"; - return VERIFY_FAILURE; - } + uint8_t* sig_der = nullptr; + size_t sig_der_length = 0; - /* - * 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; - } + uint8_t* signature = eocd + eocd_size - signature_start; + size_t signature_size = signature_start - FOOTER_SIZE; - // 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, - sig_der_length, key.rsa.get())) { - LOG(INFO) << "failed to verify against RSA key " << i; - continue; - } + LOG(INFO) << "signature (offset: " << std::hex << (length - signature_start) << ", length: " + << signature_size << "): " << print_hex(signature, signature_size); - LOG(INFO) << "whole-file signature verified against RSA key " << i; - free(sig_der); - 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, - sig_der_length, key.ec.get())) { - LOG(INFO) << "failed to verify against EC key " << i; - continue; - } + if (!read_pkcs7(signature, signature_size, &sig_der, &sig_der_length)) { + LOG(ERROR) << "Could not find signature DER block"; + return VERIFY_FAILURE; + } - LOG(INFO) << "whole-file signature verified against EC key " << i; - free(sig_der); - return VERIFY_SUCCESS; - } else { - LOG(INFO) << "Unknown key type " << key.key_type; - } - i++; - } + // 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, sig_der_length, key.rsa.get())) { + LOG(INFO) << "failed to verify against RSA key " << i; + continue; + } + + LOG(INFO) << "whole-file signature verified against RSA key " << i; + free(sig_der); + 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, sig_der_length, key.ec.get())) { + LOG(INFO) << "failed to verify against EC key " << i; + continue; + } + + LOG(INFO) << "whole-file signature verified against EC key " << i; + free(sig_der); + 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); - } - free(sig_der); - LOG(ERROR) << "failed to verify whole-file signature"; - return VERIFY_FAILURE; + 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); + } + free(sig_der); + LOG(ERROR) << "failed to verify whole-file signature"; + return VERIFY_FAILURE; } std::unique_ptr<RSA, RSADeleter> parse_rsa_key(FILE* file, uint32_t exponent) { |