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// Copyright 2017 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 "net/cert/internal/simple_path_builder_delegate.h"
#include "net/cert/internal/cert_error_params.h"
#include "net/cert/internal/cert_errors.h"
#include "net/cert/internal/signature_algorithm.h"
#include "net/cert/internal/verify_signed_data.h"
#include "third_party/boringssl/src/include/openssl/bn.h"
#include "third_party/boringssl/src/include/openssl/bytestring.h"
#include "third_party/boringssl/src/include/openssl/digest.h"
#include "third_party/boringssl/src/include/openssl/ec.h"
#include "third_party/boringssl/src/include/openssl/ec_key.h"
#include "third_party/boringssl/src/include/openssl/evp.h"
#include "third_party/boringssl/src/include/openssl/nid.h"
#include "third_party/boringssl/src/include/openssl/rsa.h"
namespace net {
DEFINE_CERT_ERROR_ID(SimplePathBuilderDelegate::kRsaModulusTooSmall,
"RSA modulus too small");
namespace {
DEFINE_CERT_ERROR_ID(kUnacceptableCurveForEcdsa,
"Only P-256, P-384, P-521 are supported for ECDSA");
bool IsAcceptableCurveForEcdsa(int curve_nid) {
switch (curve_nid) {
case NID_X9_62_prime256v1:
case NID_secp384r1:
case NID_secp521r1:
return true;
}
return false;
}
} // namespace
SimplePathBuilderDelegate::SimplePathBuilderDelegate(
size_t min_rsa_modulus_length_bits,
DigestPolicy digest_policy)
: min_rsa_modulus_length_bits_(min_rsa_modulus_length_bits),
digest_policy_(digest_policy) {}
void SimplePathBuilderDelegate::CheckPathAfterVerification(
const CertPathBuilder& path_builder,
CertPathBuilderResultPath* path) {
// Do nothing - consider all candidate paths valid.
}
bool SimplePathBuilderDelegate::IsSignatureAlgorithmAcceptable(
const SignatureAlgorithm& algorithm,
CertErrors* errors) {
// Restrict default permitted signature algorithms to:
//
// RSA PKCS#1 v1.5
// RSASSA-PSS
// ECDSA
switch (algorithm.algorithm()) {
case SignatureAlgorithmId::Dsa:
return false;
case SignatureAlgorithmId::Ecdsa:
case SignatureAlgorithmId::RsaPkcs1:
return IsAcceptableDigest(algorithm.digest());
case SignatureAlgorithmId::RsaPss:
return IsAcceptableDigest(algorithm.digest()) &&
IsAcceptableDigest(algorithm.ParamsForRsaPss()->mgf1_hash());
}
return false;
}
bool SimplePathBuilderDelegate::IsPublicKeyAcceptable(EVP_PKEY* public_key,
CertErrors* errors) {
int pkey_id = EVP_PKEY_id(public_key);
if (pkey_id == EVP_PKEY_RSA) {
// Extract the modulus length from the key.
RSA* rsa = EVP_PKEY_get0_RSA(public_key);
if (!rsa)
return false;
unsigned int modulus_length_bits = BN_num_bits(rsa->n);
if (modulus_length_bits < min_rsa_modulus_length_bits_) {
errors->AddError(
kRsaModulusTooSmall,
CreateCertErrorParams2SizeT("actual", modulus_length_bits, "minimum",
min_rsa_modulus_length_bits_));
return false;
}
return true;
}
if (pkey_id == EVP_PKEY_EC) {
// Extract the curve name.
EC_KEY* ec = EVP_PKEY_get0_EC_KEY(public_key);
if (!ec)
return false; // Unexpected.
int curve_nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec));
if (!IsAcceptableCurveForEcdsa(curve_nid)) {
errors->AddError(kUnacceptableCurveForEcdsa);
return false;
}
return true;
}
// Unexpected key type.
return false;
}
// Restricted signature digest algorithms to:
//
// SHA1 (if digest_policy_ == kWeakAllowSha1)
// SHA256
// SHA384
// SHA512
bool SimplePathBuilderDelegate::IsAcceptableDigest(
DigestAlgorithm digest) const {
switch (digest) {
case DigestAlgorithm::Md2:
case DigestAlgorithm::Md4:
case DigestAlgorithm::Md5:
return false;
case DigestAlgorithm::Sha1:
return digest_policy_ ==
SimplePathBuilderDelegate::DigestPolicy::kWeakAllowSha1;
case DigestAlgorithm::Sha256:
case DigestAlgorithm::Sha384:
case DigestAlgorithm::Sha512:
return true;
}
return false;
}
} // namespace net
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