| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include <openssl/asn1.h> |
| #include <openssl/bytestring.h> |
| #include <openssl/evp.h> |
| #include <openssl/obj.h> |
| #include <openssl/x509.h> |
| |
| #include "base/logging.h" |
| #include "crypto/scoped_openssl_types.h" |
| #include "net/cert/sha256_legacy_support_win.h" |
| |
| namespace net { |
| |
| namespace sha256_interception { |
| |
| namespace { |
| |
| typedef crypto::ScopedOpenSSL<X509_ALGOR, X509_ALGOR_free>::Type |
| ScopedX509_ALGOR; |
| |
| // Parses |subject_signature| and writes the components into |*out_tbs_data|, |
| // |*out_algor|, and |*out_signature|. The BIT STRING in the signature must be |
| // a multiple of 8 bits. |*out_signature| will have the padding byte removed. |
| // It returns true on success and false on failure. |
| bool ParseSubjectSignature(const base::StringPiece& subject_signature, |
| CBS* out_tbs_data, |
| ScopedX509_ALGOR* out_algor, |
| CBS* out_signature) { |
| CBS cbs, sequence, tbs_data, algorithm, signature; |
| CBS_init(&cbs, reinterpret_cast<const uint8_t*>(subject_signature.data()), |
| subject_signature.size()); |
| if (!CBS_get_asn1(&cbs, &sequence, CBS_ASN1_SEQUENCE) || |
| CBS_len(&cbs) != 0 || |
| !CBS_get_any_asn1_element(&sequence, &tbs_data, nullptr, nullptr) || |
| !CBS_get_asn1_element(&sequence, &algorithm, |
| CBS_ASN1_SEQUENCE) || |
| !CBS_get_asn1(&sequence, &signature, CBS_ASN1_BITSTRING) || |
| CBS_len(&sequence) != 0) { |
| return false; |
| } |
| |
| // Decode the algorithm. |
| const uint8_t* ptr = CBS_data(&algorithm); |
| ScopedX509_ALGOR algor(d2i_X509_ALGOR(NULL, &ptr, CBS_len(&algorithm))); |
| if (!algor || ptr != CBS_data(&algorithm) + CBS_len(&algorithm)) |
| return false; |
| |
| // An ASN.1 BIT STRING is encoded with a leading byte denoting the number of |
| // padding bits. All supported signature algorithms output octets, so the |
| // leading byte must be zero. |
| uint8_t padding; |
| if (!CBS_get_u8(&signature, &padding) || padding != 0) |
| return false; |
| |
| *out_tbs_data = tbs_data; |
| *out_algor = algor.Pass(); |
| *out_signature = signature; |
| return true; |
| } |
| |
| } // namespace |
| |
| BOOL CryptVerifyCertificateSignatureExHook( |
| CryptVerifyCertificateSignatureExFunc original_func, |
| HCRYPTPROV_LEGACY provider, |
| DWORD encoding_type, |
| DWORD subject_type, |
| void* subject_data, |
| DWORD issuer_type, |
| void* issuer_data, |
| DWORD flags, |
| void* extra) { |
| CHECK(original_func); |
| |
| // Only intercept if the arguments are supported. |
| if (provider != NULL || (encoding_type != X509_ASN_ENCODING) || |
| !IsSupportedSubjectType(subject_type) || subject_data == NULL || |
| !IsSupportedIssuerType(issuer_type) || issuer_data == NULL) { |
| return original_func(provider, encoding_type, subject_type, subject_data, |
| issuer_type, issuer_data, flags, extra); |
| } |
| |
| base::StringPiece subject_signature = |
| GetSubjectSignature(subject_type, subject_data); |
| bool should_intercept = false; |
| |
| // Parse out the data, AlgorithmIdentifier, and signature. |
| CBS tbs_data, signature; |
| ScopedX509_ALGOR algor; |
| if (ParseSubjectSignature(subject_signature, &tbs_data, &algor, |
| &signature)) { |
| // If the signature algorithm is RSA with one of the SHA-2 algorithms |
| // supported by BoringSSL (excluding SHA-224, which is pointless), then |
| // defer to the BoringSSL implementation. Otherwise, fall back and let the |
| // OS handle it (e.g. in case there are any algorithm policies in effect). |
| int nid = OBJ_obj2nid(algor->algorithm); |
| if (nid == NID_sha256WithRSAEncryption || |
| nid == NID_sha384WithRSAEncryption || |
| nid == NID_sha512WithRSAEncryption) { |
| should_intercept = true; |
| } |
| } |
| |
| if (!should_intercept) { |
| return original_func(provider, encoding_type, subject_type, subject_data, |
| issuer_type, issuer_data, flags, extra); |
| } |
| |
| // Rather than attempting to synthesize an EVP_PKEY by hand, just force the |
| // OS to do an ASN.1 encoding and then decode it back into BoringSSL. This |
| // is silly for performance, but safest for consistency. |
| PCERT_PUBLIC_KEY_INFO issuer_public_key = |
| GetIssuerPublicKey(issuer_type, issuer_data); |
| if (!issuer_public_key) { |
| SetLastError(static_cast<DWORD>(NTE_BAD_ALGID)); |
| return FALSE; |
| } |
| |
| uint8_t* issuer_spki_data = NULL; |
| DWORD issuer_spki_len = 0; |
| if (!CryptEncodeObjectEx(X509_ASN_ENCODING, X509_PUBLIC_KEY_INFO, |
| issuer_public_key, CRYPT_ENCODE_ALLOC_FLAG, NULL, |
| &issuer_spki_data, &issuer_spki_len)) { |
| return FALSE; |
| } |
| |
| const uint8_t* ptr = issuer_spki_data; |
| crypto::ScopedEVP_PKEY pubkey(d2i_PUBKEY(NULL, &ptr, issuer_spki_len)); |
| if (!pubkey.get() || ptr != issuer_spki_data + issuer_spki_len) { |
| ::LocalFree(issuer_spki_data); |
| SetLastError(static_cast<DWORD>(NTE_BAD_ALGID)); |
| return FALSE; |
| } |
| ::LocalFree(issuer_spki_data); |
| |
| crypto::ScopedEVP_MD_CTX md_ctx(EVP_MD_CTX_create()); |
| if (!EVP_DigestVerifyInitFromAlgorithm(md_ctx.get(), algor.get(), |
| pubkey.get()) || |
| !EVP_DigestVerifyUpdate(md_ctx.get(), CBS_data(&tbs_data), |
| CBS_len(&tbs_data)) || |
| !EVP_DigestVerifyFinal(md_ctx.get(), CBS_data(&signature), |
| CBS_len(&signature))) { |
| SetLastError(static_cast<DWORD>(NTE_BAD_SIGNATURE)); |
| return FALSE; |
| } |
| return TRUE; |
| } |
| |
| } // namespace sha256_interception |
| |
| } // namespace net |