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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "WebAuthnCoseIdentifiers.h"
#include "mozilla/dom/U2FSoftTokenManager.h"
#include "CryptoBuffer.h"
#include "mozilla/Base64.h"
#include "mozilla/Casting.h"
#include "nsNSSComponent.h"
#include "nsThreadUtils.h"
#include "pk11pub.h"
#include "prerror.h"
#include "secerr.h"
#include "WebCryptoCommon.h"
#define PREF_U2F_NSSTOKEN_COUNTER "security.webauth.softtoken_counter"
namespace mozilla {
namespace dom {
using namespace mozilla;
using mozilla::dom::CreateECParamsForCurve;
const nsCString U2FSoftTokenManager::mSecretNickname = "U2F_NSSTOKEN"_ns;
namespace {
constexpr auto kAttestCertSubjectName = "CN=Firefox U2F Soft Token"_ns;
// This U2F-compatible soft token uses FIDO U2F-compatible ECDSA keypairs
// on the SEC_OID_SECG_EC_SECP256R1 curve. When asked to Register, it will
// generate and return a new keypair KP, where the private component is wrapped
// using AES-KW with the 128-bit mWrappingKey to make an opaque "key handle".
// In other words, Register yields { KP_pub, AES-KW(KP_priv, key=mWrappingKey) }
//
// The value mWrappingKey is long-lived; it is persisted as part of the NSS DB
// for the current profile. The attestation certificates that are produced are
// ephemeral to counteract profiling. They have little use for a soft-token
// at any rate, but are required by the specification.
const uint32_t kParamLen = 32;
const uint32_t kPublicKeyLen = 65;
const uint32_t kWrappedKeyBufLen = 256;
const uint32_t kWrappingKeyByteLen = 128 / 8;
const uint32_t kSaltByteLen = 64 / 8;
const uint32_t kVersion1KeyHandleLen = 162;
constexpr auto kEcAlgorithm =
NS_LITERAL_STRING_FROM_CSTRING(WEBCRYPTO_NAMED_CURVE_P256);
const PRTime kOneDay = PRTime(PR_USEC_PER_SEC) * PRTime(60) // sec
* PRTime(60) // min
* PRTime(24); // hours
const PRTime kExpirationSlack = kOneDay; // Pre-date for clock skew
const PRTime kExpirationLife = kOneDay;
static mozilla::LazyLogModule gNSSTokenLog("webauth_u2f");
enum SoftTokenHandle {
Version1 = 0,
};
} // namespace
U2FSoftTokenManager::U2FSoftTokenManager(uint32_t aCounter)
: mInitialized(false), mCounter(aCounter) {}
/**
* Gets the first key with the given nickname from the given slot. Any other
* keys found are not returned.
* PK11_GetNextSymKey() should not be called on the returned key.
*
* @param aSlot Slot to search.
* @param aNickname Nickname the key should have.
* @return The first key found. nullptr if no key could be found.
*/
static UniquePK11SymKey GetSymKeyByNickname(const UniquePK11SlotInfo& aSlot,
const nsCString& aNickname) {
MOZ_ASSERT(aSlot);
if (NS_WARN_IF(!aSlot)) {
return nullptr;
}
MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
("Searching for a symmetric key named %s", aNickname.get()));
UniquePK11SymKey keyListHead(
PK11_ListFixedKeysInSlot(aSlot.get(), const_cast<char*>(aNickname.get()),
/* wincx */ nullptr));
if (NS_WARN_IF(!keyListHead)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Debug, ("Symmetric key not found."));
return nullptr;
}
// Sanity check PK11_ListFixedKeysInSlot() only returns keys with the correct
// nickname.
MOZ_ASSERT(aNickname ==
UniquePORTString(PK11_GetSymKeyNickname(keyListHead.get())).get());
MOZ_LOG(gNSSTokenLog, LogLevel::Debug, ("Symmetric key found!"));
// Free any remaining keys in the key list.
UniquePK11SymKey freeKey(PK11_GetNextSymKey(keyListHead.get()));
while (freeKey) {
freeKey = UniquePK11SymKey(PK11_GetNextSymKey(freeKey.get()));
}
return keyListHead;
}
static nsresult GenEcKeypair(const UniquePK11SlotInfo& aSlot,
/*out*/ UniqueSECKEYPrivateKey& aPrivKey,
/*out*/ UniqueSECKEYPublicKey& aPubKey) {
MOZ_ASSERT(aSlot);
if (NS_WARN_IF(!aSlot)) {
return NS_ERROR_INVALID_ARG;
}
UniquePLArenaPool arena(PORT_NewArena(DER_DEFAULT_CHUNKSIZE));
if (NS_WARN_IF(!arena)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// Set the curve parameters; keyParams belongs to the arena memory space
SECItem* keyParams = CreateECParamsForCurve(kEcAlgorithm, arena.get());
if (NS_WARN_IF(!keyParams)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// Generate a key pair
CK_MECHANISM_TYPE mechanism = CKM_EC_KEY_PAIR_GEN;
SECKEYPublicKey* pubKeyRaw;
aPrivKey = UniqueSECKEYPrivateKey(
PK11_GenerateKeyPair(aSlot.get(), mechanism, keyParams, &pubKeyRaw,
/* ephemeral */ false, false,
/* wincx */ nullptr));
aPubKey = UniqueSECKEYPublicKey(pubKeyRaw);
pubKeyRaw = nullptr;
if (NS_WARN_IF(!aPrivKey.get() || !aPubKey.get())) {
return NS_ERROR_FAILURE;
}
// Check that the public key has the correct length
if (NS_WARN_IF(aPubKey->u.ec.publicValue.len != kPublicKeyLen)) {
return NS_ERROR_FAILURE;
}
return NS_OK;
}
nsresult U2FSoftTokenManager::GetOrCreateWrappingKey(
const UniquePK11SlotInfo& aSlot) {
MOZ_ASSERT(aSlot);
if (NS_WARN_IF(!aSlot)) {
return NS_ERROR_INVALID_ARG;
}
// Search for an existing wrapping key. If we find it,
// store it for later and mark ourselves initialized.
mWrappingKey = GetSymKeyByNickname(aSlot, mSecretNickname);
if (mWrappingKey) {
MOZ_LOG(gNSSTokenLog, LogLevel::Debug, ("U2F Soft Token Key found."));
mInitialized = true;
return NS_OK;
}
MOZ_LOG(gNSSTokenLog, LogLevel::Info,
("No keys found. Generating new U2F Soft Token wrapping key."));
// We did not find an existing wrapping key, so we generate one in the
// persistent database (e.g, Token).
mWrappingKey = UniquePK11SymKey(PK11_TokenKeyGenWithFlags(
aSlot.get(), CKM_AES_KEY_GEN,
/* default params */ nullptr, kWrappingKeyByteLen,
/* empty keyid */ nullptr,
/* flags */ CKF_WRAP | CKF_UNWRAP,
/* attributes */ PK11_ATTR_TOKEN | PK11_ATTR_PRIVATE,
/* wincx */ nullptr));
if (NS_WARN_IF(!mWrappingKey)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to store wrapping key, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
SECStatus srv =
PK11_SetSymKeyNickname(mWrappingKey.get(), mSecretNickname.get());
if (NS_WARN_IF(srv != SECSuccess)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to set nickname, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
("Key stored, nickname set to %s.", mSecretNickname.get()));
GetMainThreadEventTarget()->Dispatch(NS_NewRunnableFunction(
"dom::U2FSoftTokenManager::GetOrCreateWrappingKey", []() {
MOZ_ASSERT(NS_IsMainThread());
Preferences::SetUint(PREF_U2F_NSSTOKEN_COUNTER, 0);
}));
return NS_OK;
}
static nsresult GetAttestationCertificate(
const UniquePK11SlotInfo& aSlot,
/*out*/ UniqueSECKEYPrivateKey& aAttestPrivKey,
/*out*/ UniqueCERTCertificate& aAttestCert) {
MOZ_ASSERT(aSlot);
if (NS_WARN_IF(!aSlot)) {
return NS_ERROR_INVALID_ARG;
}
UniqueSECKEYPublicKey pubKey;
// Construct an ephemeral keypair for this Attestation Certificate
nsresult rv = GenEcKeypair(aSlot, aAttestPrivKey, pubKey);
if (NS_WARN_IF(NS_FAILED(rv) || !aAttestPrivKey || !pubKey)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to gen keypair, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
// Construct the Attestation Certificate itself
UniqueCERTName subjectName(CERT_AsciiToName(kAttestCertSubjectName.get()));
if (NS_WARN_IF(!subjectName)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to set subject name, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
UniqueCERTSubjectPublicKeyInfo spki(
SECKEY_CreateSubjectPublicKeyInfo(pubKey.get()));
if (NS_WARN_IF(!spki)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to set SPKI, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
UniqueCERTCertificateRequest certreq(
CERT_CreateCertificateRequest(subjectName.get(), spki.get(), nullptr));
if (NS_WARN_IF(!certreq)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to gen CSR, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
PRTime now = PR_Now();
PRTime notBefore = now - kExpirationSlack;
PRTime notAfter = now + kExpirationLife;
UniqueCERTValidity validity(CERT_CreateValidity(notBefore, notAfter));
if (NS_WARN_IF(!validity)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to gen validity, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
unsigned long serial;
unsigned char* serialBytes =
mozilla::BitwiseCast<unsigned char*, unsigned long*>(&serial);
SECStatus srv =
PK11_GenerateRandomOnSlot(aSlot.get(), serialBytes, sizeof(serial));
if (NS_WARN_IF(srv != SECSuccess)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to gen serial, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
// Ensure that the most significant bit isn't set (which would
// indicate a negative number, which isn't valid for serial
// numbers).
serialBytes[0] &= 0x7f;
// Also ensure that the least significant bit on the most
// significant byte is set (to prevent a leading zero byte,
// which also wouldn't be valid).
serialBytes[0] |= 0x01;
aAttestCert = UniqueCERTCertificate(CERT_CreateCertificate(
serial, subjectName.get(), validity.get(), certreq.get()));
if (NS_WARN_IF(!aAttestCert)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to gen certificate, NSS error #%d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
PLArenaPool* arena = aAttestCert->arena;
srv = SECOID_SetAlgorithmID(arena, &aAttestCert->signature,
SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE,
/* wincx */ nullptr);
if (NS_WARN_IF(srv != SECSuccess)) {
return NS_ERROR_FAILURE;
}
// Set version to X509v3.
*(aAttestCert->version.data) = SEC_CERTIFICATE_VERSION_3;
aAttestCert->version.len = 1;
SECItem innerDER = {siBuffer, nullptr, 0};
if (NS_WARN_IF(!SEC_ASN1EncodeItem(arena, &innerDER, aAttestCert.get(),
SEC_ASN1_GET(CERT_CertificateTemplate)))) {
return NS_ERROR_FAILURE;
}
SECItem* signedCert = PORT_ArenaZNew(arena, SECItem);
if (NS_WARN_IF(!signedCert)) {
return NS_ERROR_FAILURE;
}
srv = SEC_DerSignData(arena, signedCert, innerDER.data, innerDER.len,
aAttestPrivKey.get(),
SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
if (NS_WARN_IF(srv != SECSuccess)) {
return NS_ERROR_FAILURE;
}
aAttestCert->derCert = *signedCert;
MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
("U2F Soft Token attestation certificate generated."));
return NS_OK;
}
// Set up the context for the soft U2F Token. This is called by NSS
// initialization.
nsresult U2FSoftTokenManager::Init() {
// If we've already initialized, just return.
if (mInitialized) {
return NS_OK;
}
UniquePK11SlotInfo slot(PK11_GetInternalKeySlot());
MOZ_ASSERT(slot.get());
// Search for an existing wrapping key, or create one.
nsresult rv = GetOrCreateWrappingKey(slot);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
mInitialized = true;
MOZ_LOG(gNSSTokenLog, LogLevel::Debug, ("U2F Soft Token initialized."));
return NS_OK;
}
// Convert a Private Key object into an opaque key handle, using AES Key Wrap
// with the long-lived aPersistentKey mixed with aAppParam to convert aPrivKey.
// The key handle's format is version || saltLen || salt || wrappedPrivateKey
static UniqueSECItem KeyHandleFromPrivateKey(
const UniquePK11SlotInfo& aSlot, const UniquePK11SymKey& aPersistentKey,
uint8_t* aAppParam, uint32_t aAppParamLen,
const UniqueSECKEYPrivateKey& aPrivKey) {
MOZ_ASSERT(aSlot);
MOZ_ASSERT(aPersistentKey);
MOZ_ASSERT(aAppParam);
MOZ_ASSERT(aPrivKey);
if (NS_WARN_IF(!aSlot || !aPersistentKey || !aPrivKey || !aAppParam)) {
return nullptr;
}
// Generate a random salt
uint8_t saltParam[kSaltByteLen];
SECStatus srv =
PK11_GenerateRandomOnSlot(aSlot.get(), saltParam, sizeof(saltParam));
if (NS_WARN_IF(srv != SECSuccess)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to generate a salt, NSS error #%d", PORT_GetError()));
return nullptr;
}
// Prepare the HKDF (https://tools.ietf.org/html/rfc5869)
CK_NSS_HKDFParams hkdfParams = {true, saltParam, sizeof(saltParam),
true, aAppParam, aAppParamLen};
SECItem kdfParams = {siBuffer, (unsigned char*)&hkdfParams,
sizeof(hkdfParams)};
// Derive a wrapping key from aPersistentKey, the salt, and the aAppParam.
// CKM_AES_KEY_GEN and CKA_WRAP are key type and usage attributes of the
// derived symmetric key and don't matter because we ignore them anyway.
UniquePK11SymKey wrapKey(
PK11_Derive(aPersistentKey.get(), CKM_NSS_HKDF_SHA256, &kdfParams,
CKM_AES_KEY_GEN, CKA_WRAP, kWrappingKeyByteLen));
if (NS_WARN_IF(!wrapKey.get())) {
MOZ_LOG(
gNSSTokenLog, LogLevel::Warning,
("Failed to derive a wrapping key, NSS error #%d", PORT_GetError()));
return nullptr;
}
UniqueSECItem wrappedKey(::SECITEM_AllocItem(/* default arena */ nullptr,
/* no buffer */ nullptr,
kWrappedKeyBufLen));
if (NS_WARN_IF(!wrappedKey)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
return nullptr;
}
UniqueSECItem param(PK11_ParamFromIV(CKM_NSS_AES_KEY_WRAP_PAD,
/* default IV */ nullptr));
srv =
PK11_WrapPrivKey(aSlot.get(), wrapKey.get(), aPrivKey.get(),
CKM_NSS_AES_KEY_WRAP_PAD, param.get(), wrappedKey.get(),
/* wincx */ nullptr);
if (NS_WARN_IF(srv != SECSuccess)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Failed to wrap U2F key, NSS error #%d", PORT_GetError()));
return nullptr;
}
// Concatenate the salt and the wrapped Private Key together
mozilla::dom::CryptoBuffer keyHandleBuf;
if (NS_WARN_IF(!keyHandleBuf.SetCapacity(
wrappedKey.get()->len + sizeof(saltParam) + 2, mozilla::fallible))) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
return nullptr;
}
// It's OK to ignore the return values here because we're writing into
// pre-allocated space
(void)keyHandleBuf.AppendElement(SoftTokenHandle::Version1,
mozilla::fallible);
(void)keyHandleBuf.AppendElement(sizeof(saltParam), mozilla::fallible);
(void)keyHandleBuf.AppendElements(saltParam, sizeof(saltParam),
mozilla::fallible);
keyHandleBuf.AppendSECItem(wrappedKey.get());
UniqueSECItem keyHandle(::SECITEM_AllocItem(nullptr, nullptr, 0));
if (NS_WARN_IF(!keyHandle)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
return nullptr;
}
if (NS_WARN_IF(!keyHandleBuf.ToSECItem(/* default arena */ nullptr,
keyHandle.get()))) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
return nullptr;
}
return keyHandle;
}
// Convert an opaque key handle aKeyHandle back into a Private Key object, using
// the long-lived aPersistentKey mixed with aAppParam and the AES Key Wrap
// algorithm.
static UniqueSECKEYPrivateKey PrivateKeyFromKeyHandle(
const UniquePK11SlotInfo& aSlot, const UniquePK11SymKey& aPersistentKey,
uint8_t* aKeyHandle, uint32_t aKeyHandleLen, uint8_t* aAppParam,
uint32_t aAppParamLen) {
MOZ_ASSERT(aSlot);
MOZ_ASSERT(aPersistentKey);
MOZ_ASSERT(aKeyHandle);
MOZ_ASSERT(aAppParam);
MOZ_ASSERT(aAppParamLen == SHA256_LENGTH);
if (NS_WARN_IF(!aSlot || !aPersistentKey || !aKeyHandle || !aAppParam ||
aAppParamLen != SHA256_LENGTH)) {
return nullptr;
}
// As we only support one key format ourselves (right now), fail early if
// we aren't that length
if (NS_WARN_IF(aKeyHandleLen != kVersion1KeyHandleLen)) {
return nullptr;
}
if (NS_WARN_IF(aKeyHandle[0] != SoftTokenHandle::Version1)) {
// Unrecognized version
return nullptr;
}
uint8_t saltLen = aKeyHandle[1];
uint8_t* saltPtr = aKeyHandle + 2;
if (NS_WARN_IF(saltLen != kSaltByteLen)) {
return nullptr;
}
// Prepare the HKDF (https://tools.ietf.org/html/rfc5869)
CK_NSS_HKDFParams hkdfParams = {true, saltPtr, saltLen,
true, aAppParam, aAppParamLen};
SECItem kdfParams = {siBuffer, (unsigned char*)&hkdfParams,
sizeof(hkdfParams)};
// Derive a wrapping key from aPersistentKey, the salt, and the aAppParam.
// CKM_AES_KEY_GEN and CKA_WRAP are key type and usage attributes of the
// derived symmetric key and don't matter because we ignore them anyway.
UniquePK11SymKey wrapKey(
PK11_Derive(aPersistentKey.get(), CKM_NSS_HKDF_SHA256, &kdfParams,
CKM_AES_KEY_GEN, CKA_WRAP, kWrappingKeyByteLen));
if (NS_WARN_IF(!wrapKey.get())) {
MOZ_LOG(
gNSSTokenLog, LogLevel::Warning,
("Failed to derive a wrapping key, NSS error #%d", PORT_GetError()));
return nullptr;
}
uint8_t wrappedLen = aKeyHandleLen - saltLen - 2;
uint8_t* wrappedPtr = aKeyHandle + saltLen + 2;
ScopedAutoSECItem wrappedKeyItem(wrappedLen);
memcpy(wrappedKeyItem.data, wrappedPtr, wrappedKeyItem.len);
ScopedAutoSECItem pubKey(kPublicKeyLen);
UniqueSECItem param(PK11_ParamFromIV(CKM_NSS_AES_KEY_WRAP_PAD,
/* default IV */ nullptr));
CK_ATTRIBUTE_TYPE usages[] = {CKA_SIGN};
int usageCount = 1;
UniqueSECKEYPrivateKey unwrappedKey(
PK11_UnwrapPrivKey(aSlot.get(), wrapKey.get(), CKM_NSS_AES_KEY_WRAP_PAD,
param.get(), &wrappedKeyItem,
/* no nickname */ nullptr,
/* discard pubkey */ &pubKey,
/* not permanent */ false,
/* non-exportable */ true, CKK_EC, usages, usageCount,
/* wincx */ nullptr));
if (NS_WARN_IF(!unwrappedKey)) {
// Not our key.
MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
("Could not unwrap key handle, NSS Error #%d", PORT_GetError()));
return nullptr;
}
return unwrappedKey;
}
// IsRegistered determines if the provided key handle is usable by this token.
nsresult U2FSoftTokenManager::IsRegistered(const nsTArray<uint8_t>& aKeyHandle,
const nsTArray<uint8_t>& aAppParam,
bool& aResult) {
if (!mInitialized) {
nsresult rv = Init();
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
}
UniquePK11SlotInfo slot(PK11_GetInternalSlot());
MOZ_ASSERT(slot.get());
// Decode the key handle
UniqueSECKEYPrivateKey privKey = PrivateKeyFromKeyHandle(
slot, mWrappingKey, const_cast<uint8_t*>(aKeyHandle.Elements()),
aKeyHandle.Length(), const_cast<uint8_t*>(aAppParam.Elements()),
aAppParam.Length());
aResult = privKey.get() != nullptr;
return NS_OK;
}
// A U2F Register operation causes a new key pair to be generated by the token.
// The token then returns the public key of the key pair, and a handle to the
// private key, which is a fancy way of saying "key wrapped private key", as
// well as the generated attestation certificate and a signature using that
// certificate's private key.
//
// The KeyHandleFromPrivateKey and PrivateKeyFromKeyHandle methods perform
// the actual key wrap/unwrap operations.
//
// The format of the return registration data is as follows:
//
// Bytes Value
// 1 0x05
// 65 public key
// 1 key handle length
// * key handle
// ASN.1 attestation certificate
// * attestation signature
//
RefPtr<U2FRegisterPromise> U2FSoftTokenManager::Register(
const WebAuthnMakeCredentialInfo& aInfo, bool aForceNoneAttestation) {
if (!mInitialized) {
nsresult rv = Init();
if (NS_WARN_IF(NS_FAILED(rv))) {
return U2FRegisterPromise::CreateAndReject(rv, __func__);
}
}
if (aInfo.Extra().isSome()) {
const auto& extra = aInfo.Extra().ref();
const WebAuthnAuthenticatorSelection& sel = extra.AuthenticatorSelection();
UserVerificationRequirement userVerificaitonRequirement =
sel.userVerificationRequirement();
bool requireUserVerification =
userVerificaitonRequirement == UserVerificationRequirement::Required;
bool requirePlatformAttachment = false;
if (sel.authenticatorAttachment().isSome()) {
const AuthenticatorAttachment authenticatorAttachment =
sel.authenticatorAttachment().value();
if (authenticatorAttachment == AuthenticatorAttachment::Platform) {
requirePlatformAttachment = true;
}
}
// The U2F softtoken neither supports resident keys or
// user verification, nor is it a platform authenticator.
if (sel.requireResidentKey() || requireUserVerification ||
requirePlatformAttachment) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_DOM_NOT_ALLOWED_ERR,
__func__);
}
nsTArray<CoseAlg> coseAlgos;
for (const auto& coseAlg : extra.coseAlgs()) {
switch (static_cast<CoseAlgorithmIdentifier>(coseAlg.alg())) {
case CoseAlgorithmIdentifier::ES256:
coseAlgos.AppendElement(coseAlg);
break;
default:
continue;
}
}
// Only if no algorithms were specified, default to the one the soft token
// supports.
if (extra.coseAlgs().IsEmpty()) {
coseAlgos.AppendElement(
static_cast<int32_t>(CoseAlgorithmIdentifier::ES256));
}
// If there are no acceptable/supported algorithms, reject the promise.
if (coseAlgos.IsEmpty()) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_DOM_NOT_SUPPORTED_ERR,
__func__);
}
}
CryptoBuffer rpIdHash, clientDataHash;
NS_ConvertUTF16toUTF8 rpId(aInfo.RpId());
nsresult rv = BuildTransactionHashes(rpId, aInfo.ClientDataJSON(), rpIdHash,
clientDataHash);
if (NS_WARN_IF(NS_FAILED(rv))) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_DOM_UNKNOWN_ERR,
__func__);
}
// Optional exclusion list.
for (const WebAuthnScopedCredential& cred : aInfo.ExcludeList()) {
bool isRegistered = false;
nsresult rv = IsRegistered(cred.id(), rpIdHash, isRegistered);
if (NS_FAILED(rv)) {
return U2FRegisterPromise::CreateAndReject(rv, __func__);
}
if (isRegistered) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_DOM_INVALID_STATE_ERR,
__func__);
}
}
// We should already have a wrapping key
MOZ_ASSERT(mWrappingKey);
UniquePK11SlotInfo slot(PK11_GetInternalSlot());
MOZ_ASSERT(slot.get());
// Construct a one-time-use Attestation Certificate
UniqueSECKEYPrivateKey attestPrivKey;
UniqueCERTCertificate attestCert;
rv = GetAttestationCertificate(slot, attestPrivKey, attestCert);
if (NS_WARN_IF(NS_FAILED(rv))) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
MOZ_ASSERT(attestCert);
MOZ_ASSERT(attestPrivKey);
// Generate a new keypair; the private will be wrapped into a Key Handle
UniqueSECKEYPrivateKey privKey;
UniqueSECKEYPublicKey pubKey;
rv = GenEcKeypair(slot, privKey, pubKey);
if (NS_WARN_IF(NS_FAILED(rv))) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
// The key handle will be the result of keywrap(privKey, key=mWrappingKey)
UniqueSECItem keyHandleItem = KeyHandleFromPrivateKey(
slot, mWrappingKey, const_cast<uint8_t*>(rpIdHash.Elements()),
rpIdHash.Length(), privKey);
if (NS_WARN_IF(!keyHandleItem.get())) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
// Sign the challenge using the Attestation privkey (from attestCert)
mozilla::dom::CryptoBuffer signedDataBuf;
if (NS_WARN_IF(!signedDataBuf.SetCapacity(
1 + rpIdHash.Length() + clientDataHash.Length() + keyHandleItem->len +
kPublicKeyLen,
mozilla::fallible))) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY,
__func__);
}
// // It's OK to ignore the return values here because we're writing into
// // pre-allocated space
(void)signedDataBuf.AppendElement(0x00, mozilla::fallible);
(void)signedDataBuf.AppendElements(rpIdHash, mozilla::fallible);
(void)signedDataBuf.AppendElements(clientDataHash, mozilla::fallible);
signedDataBuf.AppendSECItem(keyHandleItem.get());
signedDataBuf.AppendSECItem(pubKey->u.ec.publicValue);
ScopedAutoSECItem signatureItem;
SECStatus srv = SEC_SignData(&signatureItem, signedDataBuf.Elements(),
signedDataBuf.Length(), attestPrivKey.get(),
SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
if (NS_WARN_IF(srv != SECSuccess)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Signature failure: %d", PORT_GetError()));
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
// Serialize the registration data
mozilla::dom::CryptoBuffer registrationBuf;
if (NS_WARN_IF(!registrationBuf.SetCapacity(
1 + kPublicKeyLen + 1 + keyHandleItem->len +
attestCert.get()->derCert.len + signatureItem.len,
mozilla::fallible))) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY,
__func__);
}
(void)registrationBuf.AppendElement(0x05, mozilla::fallible);
registrationBuf.AppendSECItem(pubKey->u.ec.publicValue);
(void)registrationBuf.AppendElement(keyHandleItem->len, mozilla::fallible);
registrationBuf.AppendSECItem(keyHandleItem.get());
registrationBuf.AppendSECItem(attestCert.get()->derCert);
registrationBuf.AppendSECItem(signatureItem);
CryptoBuffer keyHandleBuf;
if (!keyHandleBuf.AppendSECItem(keyHandleItem.get())) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
CryptoBuffer attestCertBuf;
if (!attestCertBuf.AppendSECItem(attestCert.get()->derCert)) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
CryptoBuffer signatureBuf;
if (!signatureBuf.AppendSECItem(signatureItem)) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
CryptoBuffer pubKeyBuf;
if (!pubKeyBuf.AppendSECItem(pubKey->u.ec.publicValue)) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
CryptoBuffer attObj;
rv = AssembleAttestationObject(rpIdHash, pubKeyBuf, keyHandleBuf,
attestCertBuf, signatureBuf,
aForceNoneAttestation, attObj);
if (NS_FAILED(rv)) {
return U2FRegisterPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
nsTArray<WebAuthnExtensionResult> extensions;
WebAuthnMakeCredentialResult result(aInfo.ClientDataJSON(), attObj,
keyHandleBuf, registrationBuf,
extensions);
return U2FRegisterPromise::CreateAndResolve(std::move(result), __func__);
}
bool U2FSoftTokenManager::FindRegisteredKeyHandle(
const nsTArray<nsTArray<uint8_t>>& aAppIds,
const nsTArray<WebAuthnScopedCredential>& aCredentials,
/*out*/ nsTArray<uint8_t>& aKeyHandle,
/*out*/ nsTArray<uint8_t>& aAppId) {
for (const nsTArray<uint8_t>& app_id : aAppIds) {
for (const WebAuthnScopedCredential& cred : aCredentials) {
bool isRegistered = false;
nsresult rv = IsRegistered(cred.id(), app_id, isRegistered);
if (NS_SUCCEEDED(rv) && isRegistered) {
aKeyHandle.Assign(cred.id());
aAppId.Assign(app_id);
return true;
}
}
}
return false;
}
// A U2F Sign operation creates a signature over the "param" arguments (plus
// some other stuff) using the private key indicated in the key handle argument.
//
// The format of the signed data is as follows:
//
// 32 Application parameter
// 1 User presence (0x01)
// 4 Counter
// 32 Challenge parameter
//
// The format of the signature data is as follows:
//
// 1 User presence
// 4 Counter
// * Signature
//
RefPtr<U2FSignPromise> U2FSoftTokenManager::Sign(
const WebAuthnGetAssertionInfo& aInfo) {
if (!mInitialized) {
nsresult rv = Init();
if (NS_WARN_IF(NS_FAILED(rv))) {
return U2FSignPromise::CreateAndReject(rv, __func__);
}
}
CryptoBuffer rpIdHash, clientDataHash;
NS_ConvertUTF16toUTF8 rpId(aInfo.RpId());
nsresult rv = BuildTransactionHashes(rpId, aInfo.ClientDataJSON(), rpIdHash,
clientDataHash);
if (NS_WARN_IF(NS_FAILED(rv))) {
return U2FSignPromise::CreateAndReject(NS_ERROR_DOM_UNKNOWN_ERR, __func__);
}
nsTArray<nsTArray<uint8_t>> appIds;
appIds.AppendElement(std::move(rpIdHash));
Maybe<nsTArray<uint8_t>> appIdHashExt = Nothing();
if (aInfo.Extra().isSome()) {
const auto& extra = aInfo.Extra().ref();
UserVerificationRequirement userVerificaitonReq =
extra.userVerificationRequirement();
// The U2F softtoken doesn't support user verification.
if (userVerificaitonReq == UserVerificationRequirement::Required) {
return U2FSignPromise::CreateAndReject(NS_ERROR_DOM_NOT_ALLOWED_ERR,
__func__);
}
// Process extensions.
for (const WebAuthnExtension& ext : extra.Extensions()) {
if (ext.type() == WebAuthnExtension::TWebAuthnExtensionAppId) {
appIdHashExt = Some(ext.get_WebAuthnExtensionAppId().AppId().Clone());
appIds.AppendElement(appIdHashExt->Clone());
}
}
}
nsTArray<uint8_t> chosenAppId;
nsTArray<uint8_t> keyHandle;
// Fail if we can't find a valid key handle.
if (!FindRegisteredKeyHandle(appIds, aInfo.AllowList(), keyHandle,
chosenAppId)) {
return U2FSignPromise::CreateAndReject(NS_ERROR_DOM_INVALID_STATE_ERR,
__func__);
}
MOZ_ASSERT(mWrappingKey);
UniquePK11SlotInfo slot(PK11_GetInternalSlot());
MOZ_ASSERT(slot.get());
if (NS_WARN_IF((clientDataHash.Length() != kParamLen) ||
(chosenAppId.Length() != kParamLen))) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Parameter lengths are wrong! challenge=%d app=%d expected=%d",
(uint32_t)clientDataHash.Length(), (uint32_t)chosenAppId.Length(),
kParamLen));
return U2FSignPromise::CreateAndReject(NS_ERROR_ILLEGAL_VALUE, __func__);
}
// Decode the key handle
UniqueSECKEYPrivateKey privKey = PrivateKeyFromKeyHandle(
slot, mWrappingKey, const_cast<uint8_t*>(keyHandle.Elements()),
keyHandle.Length(), const_cast<uint8_t*>(chosenAppId.Elements()),
chosenAppId.Length());
if (NS_WARN_IF(!privKey.get())) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Couldn't get the priv key!"));
return U2FSignPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
// Increment the counter and turn it into a SECItem
mCounter += 1;
ScopedAutoSECItem counterItem(4);
counterItem.data[0] = (mCounter >> 24) & 0xFF;
counterItem.data[1] = (mCounter >> 16) & 0xFF;
counterItem.data[2] = (mCounter >> 8) & 0xFF;
counterItem.data[3] = (mCounter >> 0) & 0xFF;
uint32_t counter = mCounter;
GetMainThreadEventTarget()->Dispatch(
NS_NewRunnableFunction("dom::U2FSoftTokenManager::Sign", [counter]() {
MOZ_ASSERT(NS_IsMainThread());
Preferences::SetUint(PREF_U2F_NSSTOKEN_COUNTER, counter);
}));
// Compute the signature
mozilla::dom::CryptoBuffer signedDataBuf;
if (NS_WARN_IF(!signedDataBuf.SetCapacity(1 + 4 + (2 * kParamLen),
mozilla::fallible))) {
return U2FSignPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY, __func__);
}
// It's OK to ignore the return values here because we're writing into
// pre-allocated space
(void)signedDataBuf.AppendElements(chosenAppId.Elements(),
chosenAppId.Length(), mozilla::fallible);
(void)signedDataBuf.AppendElement(0x01, mozilla::fallible);
signedDataBuf.AppendSECItem(counterItem);
(void)signedDataBuf.AppendElements(
clientDataHash.Elements(), clientDataHash.Length(), mozilla::fallible);
if (MOZ_LOG_TEST(gNSSTokenLog, LogLevel::Debug)) {
nsAutoCString base64;
nsresult rv =
Base64URLEncode(signedDataBuf.Length(), signedDataBuf.Elements(),
Base64URLEncodePaddingPolicy::Omit, base64);
if (NS_WARN_IF(NS_FAILED(rv))) {
return U2FSignPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
("U2F Token signing bytes (base64): %s", base64.get()));
}
ScopedAutoSECItem signatureItem;
SECStatus srv = SEC_SignData(&signatureItem, signedDataBuf.Elements(),
signedDataBuf.Length(), privKey.get(),
SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
if (NS_WARN_IF(srv != SECSuccess)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Signature failure: %d", PORT_GetError()));
return U2FSignPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
// Assemble the signature data into a buffer for return
mozilla::dom::CryptoBuffer signatureDataBuf;
if (NS_WARN_IF(!signatureDataBuf.SetCapacity(
1 + counterItem.len + signatureItem.len, mozilla::fallible))) {
return U2FSignPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY, __func__);
}
// It's OK to ignore the return values here because we're writing into
// pre-allocated space
(void)signatureDataBuf.AppendElement(0x01, mozilla::fallible);
signatureDataBuf.AppendSECItem(counterItem);
signatureDataBuf.AppendSECItem(signatureItem);
nsTArray<WebAuthnExtensionResult> extensions;
if (appIdHashExt) {
bool usedAppId = (chosenAppId == appIdHashExt.ref());
extensions.AppendElement(WebAuthnExtensionResultAppId(usedAppId));
}
CryptoBuffer counterBuf;
if (!counterBuf.AppendSECItem(counterItem)) {
return U2FSignPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY, __func__);
}
CryptoBuffer signatureBuf;
if (!signatureBuf.AppendSECItem(signatureItem)) {
return U2FSignPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY, __func__);
}
CryptoBuffer chosenAppIdBuf;
if (!chosenAppIdBuf.Assign(chosenAppId)) {
return U2FSignPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY, __func__);
}
CryptoBuffer authenticatorData;
CryptoBuffer emptyAttestationData;
rv = AssembleAuthenticatorData(chosenAppIdBuf, 0x01, counterBuf,
emptyAttestationData, authenticatorData);
if (NS_WARN_IF(NS_FAILED(rv))) {
return U2FSignPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
}
nsTArray<uint8_t> userHandle;
WebAuthnGetAssertionResult result(aInfo.ClientDataJSON(), keyHandle,
signatureBuf, authenticatorData, extensions,
signatureDataBuf, userHandle);
return U2FSignPromise::CreateAndResolve(std::move(result), __func__);
}
void U2FSoftTokenManager::Cancel() {
// This implementation is sync, requests can't be aborted.
}
} // namespace dom
} // namespace mozilla