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gecko-dev/security/manager/ssl/nsNSSU2FToken.cpp

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30 KiB
C++
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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 "nsNSSU2FToken.h"
#include "CryptoBuffer.h"
#include "mozilla/Base64.h"
#include "mozilla/Casting.h"
#include "nsNSSComponent.h"
#include "pk11pub.h"
#include "prerror.h"
#include "secerr.h"
#include "WebCryptoCommon.h"
using namespace mozilla;
using mozilla::dom::CreateECParamsForCurve;
NS_IMPL_ISUPPORTS(nsNSSU2FToken, nsIU2FToken, nsINSSU2FToken)
// Not named "security.webauth.u2f_softtoken_counter" because setting that
// name causes the window.u2f object to disappear until preferences get
// reloaded, as its' pref is a substring!
#define PREF_U2F_NSSTOKEN_COUNTER "security.webauth.softtoken_counter"
const nsCString nsNSSU2FToken::mSecretNickname =
NS_LITERAL_CSTRING("U2F_NSSTOKEN");
const nsString nsNSSU2FToken::mVersion =
NS_LITERAL_STRING("U2F_V2");
const char* kAttestCertSubjectName = "CN=Firefox U2F Soft Token";
// 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;
NS_NAMED_LITERAL_STRING(kEcAlgorithm, 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;
enum SoftTokenHandle {
Version1 = 0,
};
static mozilla::LazyLogModule gNSSTokenLog("webauth_u2f");
nsNSSU2FToken::nsNSSU2FToken()
: mInitialized(false)
{}
nsNSSU2FToken::~nsNSSU2FToken()
{
nsNSSShutDownPreventionLock locker;
if (isAlreadyShutDown()) {
return;
}
destructorSafeDestroyNSSReference();
shutdown(ShutdownCalledFrom::Object);
}
void
nsNSSU2FToken::virtualDestroyNSSReference()
{
destructorSafeDestroyNSSReference();
}
void
nsNSSU2FToken::destructorSafeDestroyNSSReference()
{
mWrappingKey = nullptr;
}
/**
* 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,
const nsNSSShutDownPreventionLock&)
{
MOZ_ASSERT(aSlot);
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 (!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,
const nsNSSShutDownPreventionLock&)
{
MOZ_ASSERT(aSlot);
if (!aSlot) {
return NS_ERROR_INVALID_ARG;
}
UniquePLArenaPool arena(PORT_NewArena(DER_DEFAULT_CHUNKSIZE));
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 (!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 (!aPrivKey.get() || !aPubKey.get()) {
return NS_ERROR_FAILURE;
}
// Check that the public key has the correct length
if (aPubKey->u.ec.publicValue.len != kPublicKeyLen) {
return NS_ERROR_FAILURE;
}
return NS_OK;
}
nsresult
nsNSSU2FToken::GetOrCreateWrappingKey(const UniquePK11SlotInfo& aSlot,
const nsNSSShutDownPreventionLock& locker)
{
MOZ_ASSERT(aSlot);
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, locker);
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 (!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 (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()));
Preferences::SetUint(PREF_U2F_NSSTOKEN_COUNTER, 0);
return NS_OK;
}
static nsresult
GetAttestationCertificate(const UniquePK11SlotInfo& aSlot,
/*out*/ UniqueSECKEYPrivateKey& aAttestPrivKey,
/*out*/ UniqueCERTCertificate& aAttestCert,
const nsNSSShutDownPreventionLock& locker)
{
MOZ_ASSERT(aSlot);
if (!aSlot) {
return NS_ERROR_INVALID_ARG;
}
UniqueSECKEYPublicKey pubKey;
// Construct an ephemeral keypair for this Attestation Certificate
nsresult rv = GenEcKeypair(aSlot, aAttestPrivKey, pubKey, locker);
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));
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 (!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 (!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 (!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 (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 (!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 (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 (!SEC_ASN1EncodeItem(arena, &innerDER, aAttestCert.get(),
SEC_ASN1_GET(CERT_CertificateTemplate))) {
return NS_ERROR_FAILURE;
}
SECItem* signedCert = PORT_ArenaZNew(arena, SECItem);
if (!signedCert) {
return NS_ERROR_FAILURE;
}
srv = SEC_DerSignData(arena, signedCert, innerDER.data, innerDER.len,
aAttestPrivKey.get(),
SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
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
nsNSSU2FToken::Init()
{
MOZ_ASSERT(NS_IsMainThread());
MOZ_ASSERT(!mInitialized);
if (mInitialized) {
return NS_ERROR_FAILURE;
}
nsNSSShutDownPreventionLock locker;
if (isAlreadyShutDown()) {
return NS_ERROR_NOT_AVAILABLE;
}
UniquePK11SlotInfo slot(PK11_GetInternalKeySlot());
MOZ_ASSERT(slot.get());
// Search for an existing wrapping key, or create one.
nsresult rv = GetOrCreateWrappingKey(slot, locker);
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,
const nsNSSShutDownPreventionLock&)
{
MOZ_ASSERT(aSlot);
MOZ_ASSERT(aPersistentKey);
MOZ_ASSERT(aAppParam);
MOZ_ASSERT(aPrivKey);
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 (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 (!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 (!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 (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 (!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
keyHandleBuf.AppendElement(SoftTokenHandle::Version1, mozilla::fallible);
keyHandleBuf.AppendElement(sizeof(saltParam), mozilla::fallible);
keyHandleBuf.AppendElements(saltParam, sizeof(saltParam), mozilla::fallible);
keyHandleBuf.AppendSECItem(wrappedKey.get());
UniqueSECItem keyHandle(SECITEM_AllocItem(nullptr, nullptr, 0));
if (!keyHandle) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Failed to allocate memory"));
return nullptr;
}
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,
const nsNSSShutDownPreventionLock&)
{
MOZ_ASSERT(aSlot);
MOZ_ASSERT(aPersistentKey);
MOZ_ASSERT(aKeyHandle);
MOZ_ASSERT(aAppParam);
MOZ_ASSERT(aAppParamLen == SHA256_LENGTH);
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 (aKeyHandleLen != kVersion1KeyHandleLen) {
return nullptr;
}
if (aKeyHandle[0] != SoftTokenHandle::Version1) {
// Unrecognized version
return nullptr;
}
uint8_t saltLen = aKeyHandle[1];
uint8_t* saltPtr = aKeyHandle + 2;
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 (!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 (!unwrappedKey) {
// Not our key.
MOZ_LOG(gNSSTokenLog, LogLevel::Debug,
("Could not unwrap key handle, NSS Error #%d", PORT_GetError()));
return nullptr;
}
return unwrappedKey;
}
// Return whether the provided version is supported by this token.
NS_IMETHODIMP
nsNSSU2FToken::IsCompatibleVersion(const nsAString& aVersion, bool* aResult)
{
NS_ENSURE_ARG_POINTER(aResult);
MOZ_ASSERT(mInitialized);
*aResult = (mVersion == aVersion);
return NS_OK;
}
// IsRegistered determines if the provided key handle is usable by this token.
NS_IMETHODIMP
nsNSSU2FToken::IsRegistered(uint8_t* aKeyHandle, uint32_t aKeyHandleLen,
uint8_t* aAppParam, uint32_t aAppParamLen,
bool* aResult)
{
NS_ENSURE_ARG_POINTER(aKeyHandle);
NS_ENSURE_ARG_POINTER(aAppParam);
NS_ENSURE_ARG_POINTER(aResult);
if (!NS_IsMainThread()) {
NS_ERROR("nsNSSU2FToken::IsRegistered called off the main thread");
return NS_ERROR_NOT_SAME_THREAD;
}
nsNSSShutDownPreventionLock locker;
if (isAlreadyShutDown()) {
return NS_ERROR_FAILURE;
}
MOZ_ASSERT(mInitialized);
if (!mInitialized) {
return NS_ERROR_FAILURE;
}
UniquePK11SlotInfo slot(PK11_GetInternalSlot());
MOZ_ASSERT(slot.get());
// Decode the key handle
UniqueSECKEYPrivateKey privKey = PrivateKeyFromKeyHandle(slot, mWrappingKey,
aKeyHandle,
aKeyHandleLen,
aAppParam,
aAppParamLen,
locker);
*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
//
NS_IMETHODIMP
nsNSSU2FToken::Register(uint8_t* aApplication,
uint32_t aApplicationLen,
uint8_t* aChallenge,
uint32_t aChallengeLen,
uint8_t** aRegistration,
uint32_t* aRegistrationLen)
{
NS_ENSURE_ARG_POINTER(aApplication);
NS_ENSURE_ARG_POINTER(aChallenge);
NS_ENSURE_ARG_POINTER(aRegistration);
NS_ENSURE_ARG_POINTER(aRegistrationLen);
if (!NS_IsMainThread()) {
NS_ERROR("nsNSSU2FToken::Register called off the main thread");
return NS_ERROR_NOT_SAME_THREAD;
}
nsNSSShutDownPreventionLock locker;
if (isAlreadyShutDown()) {
return NS_ERROR_NOT_AVAILABLE;
}
MOZ_ASSERT(mInitialized);
if (!mInitialized) {
return NS_ERROR_NOT_INITIALIZED;
}
// 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;
nsresult rv = GetAttestationCertificate(slot, attestPrivKey, attestCert,
locker);
if (NS_WARN_IF(NS_FAILED(rv))) {
return NS_ERROR_FAILURE;
}
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, locker);
if (NS_WARN_IF(NS_FAILED(rv))) {
return NS_ERROR_FAILURE;
}
// The key handle will be the result of keywrap(privKey, key=mWrappingKey)
UniqueSECItem keyHandleItem = KeyHandleFromPrivateKey(slot, mWrappingKey,
aApplication,
aApplicationLen,
privKey, locker);
if (!keyHandleItem.get()) {
return NS_ERROR_FAILURE;
}
// Sign the challenge using the Attestation privkey (from attestCert)
mozilla::dom::CryptoBuffer signedDataBuf;
if (!signedDataBuf.SetCapacity(1 + aApplicationLen + aChallengeLen +
keyHandleItem->len + kPublicKeyLen,
mozilla::fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// It's OK to ignore the return values here because we're writing into
// pre-allocated space
signedDataBuf.AppendElement(0x00, mozilla::fallible);
signedDataBuf.AppendElements(aApplication, aApplicationLen, mozilla::fallible);
signedDataBuf.AppendElements(aChallenge, aChallengeLen, 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 (srv != SECSuccess) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Signature failure: %d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
// Serialize the registration data
mozilla::dom::CryptoBuffer registrationBuf;
if (!registrationBuf.SetCapacity(1 + kPublicKeyLen + 1 + keyHandleItem->len +
attestCert.get()->derCert.len +
signatureItem.len, mozilla::fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
registrationBuf.AppendElement(0x05, mozilla::fallible);
registrationBuf.AppendSECItem(pubKey->u.ec.publicValue);
registrationBuf.AppendElement(keyHandleItem->len, mozilla::fallible);
registrationBuf.AppendSECItem(keyHandleItem.get());
registrationBuf.AppendSECItem(attestCert.get()->derCert);
registrationBuf.AppendSECItem(signatureItem);
if (!registrationBuf.ToNewUnsignedBuffer(aRegistration, aRegistrationLen)) {
return NS_ERROR_FAILURE;
}
return NS_OK;
}
// 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
//
NS_IMETHODIMP
nsNSSU2FToken::Sign(uint8_t* aApplication, uint32_t aApplicationLen,
uint8_t* aChallenge, uint32_t aChallengeLen,
uint8_t* aKeyHandle, uint32_t aKeyHandleLen,
uint8_t** aSignature, uint32_t* aSignatureLen)
{
NS_ENSURE_ARG_POINTER(aApplication);
NS_ENSURE_ARG_POINTER(aChallenge);
NS_ENSURE_ARG_POINTER(aKeyHandle);
NS_ENSURE_ARG_POINTER(aKeyHandleLen);
NS_ENSURE_ARG_POINTER(aSignature);
NS_ENSURE_ARG_POINTER(aSignatureLen);
if (!NS_IsMainThread()) {
NS_ERROR("nsNSSU2FToken::Sign called off the main thread");
return NS_ERROR_NOT_SAME_THREAD;
}
nsNSSShutDownPreventionLock locker;
if (isAlreadyShutDown()) {
return NS_ERROR_NOT_AVAILABLE;
}
MOZ_ASSERT(mInitialized);
if (!mInitialized) {
return NS_ERROR_NOT_INITIALIZED;
}
MOZ_ASSERT(mWrappingKey);
UniquePK11SlotInfo slot(PK11_GetInternalSlot());
MOZ_ASSERT(slot.get());
if ((aChallengeLen != kParamLen) || (aApplicationLen != kParamLen)) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Parameter lengths are wrong! challenge=%d app=%d expected=%d",
aChallengeLen, aApplicationLen, kParamLen));
return NS_ERROR_ILLEGAL_VALUE;
}
// Decode the key handle
UniqueSECKEYPrivateKey privKey = PrivateKeyFromKeyHandle(slot, mWrappingKey,
aKeyHandle,
aKeyHandleLen,
aApplication,
aApplicationLen,
locker);
if (!privKey.get()) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning, ("Couldn't get the priv key!"));
return NS_ERROR_FAILURE;
}
// Increment the counter and turn it into a SECItem
uint32_t counter = Preferences::GetUint(PREF_U2F_NSSTOKEN_COUNTER) + 1;
Preferences::SetUint(PREF_U2F_NSSTOKEN_COUNTER, counter);
ScopedAutoSECItem counterItem(4);
counterItem.data[0] = (counter >> 24) & 0xFF;
counterItem.data[1] = (counter >> 16) & 0xFF;
counterItem.data[2] = (counter >> 8) & 0xFF;
counterItem.data[3] = (counter >> 0) & 0xFF;
// Compute the signature
mozilla::dom::CryptoBuffer signedDataBuf;
if (!signedDataBuf.SetCapacity(1 + 4 + (2 * kParamLen), mozilla::fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// It's OK to ignore the return values here because we're writing into
// pre-allocated space
signedDataBuf.AppendElements(aApplication, aApplicationLen, mozilla::fallible);
signedDataBuf.AppendElement(0x01, mozilla::fallible);
signedDataBuf.AppendSECItem(counterItem);
signedDataBuf.AppendElements(aChallenge, aChallengeLen, 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 NS_ERROR_FAILURE;
}
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 (srv != SECSuccess) {
MOZ_LOG(gNSSTokenLog, LogLevel::Warning,
("Signature failure: %d", PORT_GetError()));
return NS_ERROR_FAILURE;
}
// Assemble the signature data into a buffer for return
mozilla::dom::CryptoBuffer signatureBuf;
if (!signatureBuf.SetCapacity(1 + counterItem.len + signatureItem.len,
mozilla::fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// It's OK to ignore the return values here because we're writing into
// pre-allocated space
signatureBuf.AppendElement(0x01, mozilla::fallible);
signatureBuf.AppendSECItem(counterItem);
signatureBuf.AppendSECItem(signatureItem);
if (!signatureBuf.ToNewUnsignedBuffer(aSignature, aSignatureLen)) {
return NS_ERROR_FAILURE;
}
return NS_OK;
}
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