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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/cert/internal/cert_issuer_source_aia.h"
#include <string_view>
#include "base/containers/span.h"
#include "base/logging.h"
#include "net/cert/cert_net_fetcher.h"
#include "net/cert/x509_util.h"
#include "third_party/boringssl/src/pki/cert_errors.h"
#include "third_party/boringssl/src/pki/pem.h"
#include "url/gurl.h"
namespace net {
namespace {
// TODO(mattm): These are arbitrary choices. Re-evaluate.
const int kTimeoutMilliseconds = 10000;
const int kMaxResponseBytes = 65536;
const int kMaxFetchesPerCert = 5;
bool ParseCertFromDer(base::span<const uint8_t> data,
bssl::ParsedCertificateList* results) {
bssl::CertErrors errors;
if (!bssl::ParsedCertificate::CreateAndAddToVector(
x509_util::CreateCryptoBuffer(data),
x509_util::DefaultParseCertificateOptions(), results, &errors)) {
// TODO(crbug.com/41267838): propagate error info.
// TODO(mattm): this creates misleading log spam if one of the other Parse*
// methods is actually able to parse the data.
LOG(ERROR) << "Error parsing cert retrieved from AIA (as DER):\n"
<< errors.ToDebugString();
return false;
}
return true;
}
bool ParseCertsFromCms(base::span<const uint8_t> data,
bssl::ParsedCertificateList* results) {
std::vector<bssl::UniquePtr<CRYPTO_BUFFER>> cert_buffers;
// A "certs-only CMS message" is a PKCS#7 SignedData structure with no signed
// inner content. See RFC 3851 section 3.2.2 and RFC 2315 section 9.1.
// Note: RFC 5280 section 4.2.2.1 says that the data should be a certs-only
// CMS message, however this will actually allow a SignedData which
// contains CRLs and/or inner content, ignoring them.
if (!x509_util::CreateCertBuffersFromPKCS7Bytes(data, &cert_buffers)) {
return false;
}
bool any_succeeded = false;
for (auto& cert_buffer : cert_buffers) {
bssl::CertErrors errors;
if (!bssl::ParsedCertificate::CreateAndAddToVector(
std::move(cert_buffer), x509_util::DefaultParseCertificateOptions(),
results, &errors)) {
// TODO(crbug.com/41267838): propagate error info.
LOG(ERROR) << "Error parsing cert extracted from AIA PKCS7:\n"
<< errors.ToDebugString();
continue;
}
any_succeeded = true;
}
return any_succeeded;
}
bool ParseCertFromPem(const uint8_t* data,
size_t length,
bssl::ParsedCertificateList* results) {
std::string_view data_strpiece(reinterpret_cast<const char*>(data), length);
bssl::PEMTokenizer pem_tokenizer(data_strpiece, {"CERTIFICATE"});
if (!pem_tokenizer.GetNext())
return false;
return ParseCertFromDer(base::as_byte_span(pem_tokenizer.data()), results);
}
class AiaRequest : public bssl::CertIssuerSource::Request {
public:
AiaRequest() = default;
AiaRequest(const AiaRequest&) = delete;
AiaRequest& operator=(const AiaRequest&) = delete;
~AiaRequest() override;
// bssl::CertIssuerSource::Request implementation.
void GetNext(bssl::ParsedCertificateList* issuers) override;
void AddCertFetcherRequest(
std::unique_ptr<CertNetFetcher::Request> cert_fetcher_request);
bool AddCompletedFetchToResults(Error error,
std::vector<uint8_t> fetched_bytes,
bssl::ParsedCertificateList* results);
private:
std::vector<std::unique_ptr<CertNetFetcher::Request>> cert_fetcher_requests_;
size_t current_request_ = 0;
};
AiaRequest::~AiaRequest() = default;
void AiaRequest::GetNext(bssl::ParsedCertificateList* out_certs) {
// TODO(eroman): Rather than blocking in FIFO order, select the one that
// completes first.
while (current_request_ < cert_fetcher_requests_.size()) {
Error error;
std::vector<uint8_t> bytes;
auto req = std::move(cert_fetcher_requests_[current_request_++]);
req->WaitForResult(&error, &bytes);
if (AddCompletedFetchToResults(error, std::move(bytes), out_certs)) {
return;
}
}
}
void AiaRequest::AddCertFetcherRequest(
std::unique_ptr<CertNetFetcher::Request> cert_fetcher_request) {
DCHECK(cert_fetcher_request);
cert_fetcher_requests_.push_back(std::move(cert_fetcher_request));
}
bool AiaRequest::AddCompletedFetchToResults(
Error error,
std::vector<uint8_t> fetched_bytes,
bssl::ParsedCertificateList* results) {
if (error != OK) {
// TODO(mattm): propagate error info.
LOG(ERROR) << "AiaRequest::OnFetchCompleted got error " << error;
return false;
}
// RFC 5280 section 4.2.2.1:
//
// Conforming applications that support HTTP or FTP for accessing
// certificates MUST be able to accept individual DER encoded
// certificates and SHOULD be able to accept "certs-only" CMS messages.
// TODO(crbug.com/41405652): Some AIA responses are served as PEM, which
// is not part of RFC 5280's profile.
return ParseCertFromDer(fetched_bytes, results) ||
ParseCertsFromCms(fetched_bytes, results) ||
ParseCertFromPem(fetched_bytes.data(), fetched_bytes.size(), results);
}
} // namespace
CertIssuerSourceAia::CertIssuerSourceAia(
scoped_refptr<CertNetFetcher> cert_fetcher)
: cert_fetcher_(std::move(cert_fetcher)) {}
CertIssuerSourceAia::~CertIssuerSourceAia() = default;
void CertIssuerSourceAia::SyncGetIssuersOf(
const bssl::ParsedCertificate* cert,
bssl::ParsedCertificateList* issuers) {
// CertIssuerSourceAia never returns synchronous results.
}
void CertIssuerSourceAia::AsyncGetIssuersOf(const bssl::ParsedCertificate* cert,
std::unique_ptr<Request>* out_req) {
out_req->reset();
if (!cert->has_authority_info_access())
return;
// RFC 5280 section 4.2.2.1:
//
// An authorityInfoAccess extension may include multiple instances of
// the id-ad-caIssuers accessMethod. The different instances may
// specify different methods for accessing the same information or may
// point to different information.
std::vector<GURL> urls;
for (const auto& uri : cert->ca_issuers_uris()) {
GURL url(uri);
if (url.is_valid()) {
// TODO(mattm): do the kMaxFetchesPerCert check only on the number of
// supported URL schemes, not all the URLs.
if (urls.size() < kMaxFetchesPerCert) {
urls.push_back(url);
} else {
// TODO(mattm): propagate error info.
LOG(ERROR) << "kMaxFetchesPerCert exceeded, skipping";
}
} else {
// TODO(mattm): propagate error info.
LOG(ERROR) << "invalid AIA URL: " << uri;
}
}
if (urls.empty())
return;
auto aia_request = std::make_unique<AiaRequest>();
for (const auto& url : urls) {
// TODO(mattm): add synchronous failure mode to FetchCaIssuers interface so
// that this doesn't need to wait for async callback just to tell that an
// URL has an unsupported scheme?
aia_request->AddCertFetcherRequest(cert_fetcher_->FetchCaIssuers(
url, kTimeoutMilliseconds, kMaxResponseBytes));
}
*out_req = std::move(aia_request);
}
} // namespace net
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