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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/webauthn/unexportable_key_utils.h"
#include <cstdint>
#include <string>
#include "ash/constants/ash_features.h"
#include "ash/public/cpp/auth/active_session_auth_controller.h"
#include "ash/public/cpp/webauthn_dialog_controller.h"
#include "base/base64.h"
#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "chromeos/ash/components/osauth/impl/request/webauthn_auth_request.h"
#include "crypto/unexportable_key.h"
#include "crypto/user_verifying_key.h"
#include "third_party/abseil-cpp/absl/functional/overload.h"
#include "ui/aura/window.h"
namespace {
std::unique_ptr<crypto::UserVerifyingKeyProvider> (*g_test_override)() =
nullptr;
// UserVerifyingSigningKeyCros wraps an `UnexportableSigningKey` and presents an
// Ash InSessionAuth dialog prior to releasing a signature. The wrapped key is
// currently not hardware bound.
class UserVerifyingSigningKeyCros : public crypto::UserVerifyingSigningKey {
public:
explicit UserVerifyingSigningKeyCros(
UserVerifyingKeyProviderConfigChromeos config,
std::unique_ptr<crypto::UnexportableSigningKey> signing_key,
std::string label)
: config_(std::move(config)),
signing_key_(std::move(signing_key)),
label_(std::move(label)) {
CHECK(signing_key_);
}
~UserVerifyingSigningKeyCros() override = default;
void Sign(base::span<const uint8_t> data,
UserVerifyingKeySignatureCallback callback) override {
CHECK(config_.window);
VerifyUser(base::BindOnce(
&UserVerifyingSigningKeyCros::DoSign, weak_factory_.GetWeakPtr(),
std::vector<uint8_t>(data.begin(), data.end()), std::move(callback)));
}
std::vector<uint8_t> GetPublicKey() const override {
return signing_key_->GetSubjectPublicKeyInfo();
}
const crypto::UserVerifyingKeyLabel& GetKeyLabel() const override {
return label_;
}
private:
void VerifyUser(base::OnceCallback<void(bool)> callback) {
auto visitor = absl::Overload(
// Legacy code path.
[&](raw_ptr<ash::WebAuthNDialogController> controller) {
CHECK(controller);
controller->ShowAuthenticationDialog(config_.window, config_.rp_id,
std::move(callback));
},
// New code path.
[&](raw_ptr<ash::ActiveSessionAuthController> controller) {
CHECK(controller);
auto webauthn_auth_request =
std::make_unique<ash::WebAuthNAuthRequest>(config_.rp_id,
std::move(callback));
controller->ShowAuthDialog(std::move(webauthn_auth_request));
});
std::visit(visitor, config_.dialog_controller);
}
void DoSign(std::vector<uint8_t> data,
UserVerifyingKeySignatureCallback callback,
bool uv_success) {
if (!uv_success) {
std::move(callback).Run(base::unexpected(
crypto::UserVerifyingKeySigningError::kUserCancellation));
return;
}
std::optional<std::vector<uint8_t>> signature =
signing_key_->SignSlowly(data);
if (!signature) {
std::move(callback).Run(base::unexpected(
crypto::UserVerifyingKeySigningError::kUnknownError));
return;
}
std::move(callback).Run(std::move(*signature));
}
const UserVerifyingKeyProviderConfigChromeos config_;
const std::unique_ptr<crypto::UnexportableSigningKey> signing_key_;
const std::string label_;
base::WeakPtrFactory<UserVerifyingSigningKeyCros> weak_factory_{this};
};
class UserVerifyingKeyProviderCros : public crypto::UserVerifyingKeyProvider {
public:
explicit UserVerifyingKeyProviderCros(
UserVerifyingKeyProviderConfigChromeos config)
: config_(config) {}
~UserVerifyingKeyProviderCros() override = default;
void GenerateUserVerifyingSigningKey(
base::span<const crypto::SignatureVerifier::SignatureAlgorithm>
acceptable_algorithms,
UserVerifyingKeyCreationCallback callback) override {
std::unique_ptr<crypto::UnexportableSigningKey> key =
crypto::GetSoftwareUnsecureUnexportableKeyProvider()
->GenerateSigningKeySlowly(acceptable_algorithms);
std::string label = base::Base64Encode(key->GetWrappedKey());
std::move(callback).Run(std::make_unique<UserVerifyingSigningKeyCros>(
config_, std::move(key), std::move(label)));
}
void GetUserVerifyingSigningKey(
crypto::UserVerifyingKeyLabel key_label,
UserVerifyingKeyCreationCallback callback) override {
std::optional<std::vector<uint8_t>> wrapped_private_key =
base::Base64Decode(key_label);
if (!wrapped_private_key) {
std::move(callback).Run(
base::unexpected(crypto::UserVerifyingKeyCreationError::kNotFound));
return;
}
std::unique_ptr<crypto::UnexportableSigningKey> signing_key =
crypto::GetSoftwareUnsecureUnexportableKeyProvider()
->FromWrappedSigningKeySlowly(*wrapped_private_key);
std::move(callback).Run(std::make_unique<UserVerifyingSigningKeyCros>(
config_, std::move(signing_key), std::move(key_label)));
}
void DeleteUserVerifyingKey(
crypto::UserVerifyingKeyLabel key_label,
base::OnceCallback<void(bool)> callback) override {
// UserVerifyingSigningKeyCros is stateless, so this is a no-op.
std::move(callback).Run(true);
}
private:
UserVerifyingKeyProviderConfigChromeos config_;
};
} // namespace
UserVerifyingKeyProviderConfigChromeos::UserVerifyingKeyProviderConfigChromeos(
AuthDialogController dialog_controller,
aura::Window* window,
std::string rp_id)
: dialog_controller(dialog_controller),
window(window),
rp_id(std::move(rp_id)) {}
UserVerifyingKeyProviderConfigChromeos::
~UserVerifyingKeyProviderConfigChromeos() = default;
UserVerifyingKeyProviderConfigChromeos::UserVerifyingKeyProviderConfigChromeos(
const UserVerifyingKeyProviderConfigChromeos&) = default;
UserVerifyingKeyProviderConfigChromeos&
UserVerifyingKeyProviderConfigChromeos::operator=(
const UserVerifyingKeyProviderConfigChromeos&) = default;
std::unique_ptr<crypto::UserVerifyingKeyProvider>
GetWebAuthnUserVerifyingKeyProvider(
UserVerifyingKeyProviderConfigChromeos config) {
if (g_test_override) {
return g_test_override();
}
return std::make_unique<UserVerifyingKeyProviderCros>(std::move(config));
}
// ChromeOS doesn't use the UserVerifyingKeyProvider provided by //crypto, so
// the test override is handled separately as well.
void OverrideWebAuthnChromeosUserVerifyingKeyProviderForTesting(
std::unique_ptr<crypto::UserVerifyingKeyProvider> (*func)()) {
if (g_test_override) {
// Prevent nesting of scoped providers.
CHECK(!func);
g_test_override = nullptr;
} else {
g_test_override = func;
}
}
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