blob: b5fe2485949e72c8a52beb512ad500fecd329d0c [file] [log] [blame]
// Copyright (c) 2012 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/cert_verify_proc_win.h"
#include <algorithm>
#include <memory>
#include <string>
#include <vector>
#include "base/memory/free_deleter.h"
#include "base/metrics/histogram_macros.h"
#include "base/stl_util.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/thread_local.h"
#include "crypto/capi_util.h"
#include "crypto/scoped_capi_types.h"
#include "crypto/sha2.h"
#include "net/base/net_errors.h"
#include "net/cert/asn1_util.h"
#include "net/cert/cert_status_flags.h"
#include "net/cert/cert_verifier.h"
#include "net/cert/cert_verify_result.h"
#include "net/cert/crl_set.h"
#include "net/cert/ev_root_ca_metadata.h"
#include "net/cert/known_roots.h"
#include "net/cert/known_roots_win.h"
#include "net/cert/test_root_certs.h"
#include "net/cert/x509_certificate.h"
#include "net/cert/x509_util_win.h"
#if !defined(CERT_TRUST_HAS_WEAK_SIGNATURE)
// This was introduced in Windows 8 / Windows Server 2012, but retroactively
// ported as far back as Windows XP via system update.
#define CERT_TRUST_HAS_WEAK_SIGNATURE 0x00100000
#endif
namespace net {
namespace {
struct FreeChainEngineFunctor {
void operator()(HCERTCHAINENGINE engine) const {
if (engine)
CertFreeCertificateChainEngine(engine);
}
};
struct FreeCertChainContextFunctor {
void operator()(PCCERT_CHAIN_CONTEXT chain_context) const {
if (chain_context)
CertFreeCertificateChain(chain_context);
}
};
typedef crypto::ScopedCAPIHandle<HCERTCHAINENGINE, FreeChainEngineFunctor>
ScopedHCERTCHAINENGINE;
typedef std::unique_ptr<const CERT_CHAIN_CONTEXT, FreeCertChainContextFunctor>
ScopedPCCERT_CHAIN_CONTEXT;
//-----------------------------------------------------------------------------
int MapSecurityError(SECURITY_STATUS err) {
// There are numerous security error codes, but these are the ones we thus
// far find interesting.
switch (err) {
case SEC_E_WRONG_PRINCIPAL: // Schannel
case CERT_E_CN_NO_MATCH: // CryptoAPI
return ERR_CERT_COMMON_NAME_INVALID;
case SEC_E_UNTRUSTED_ROOT: // Schannel
case CERT_E_UNTRUSTEDROOT: // CryptoAPI
case TRUST_E_CERT_SIGNATURE: // CryptoAPI. Caused by weak crypto or bad
// signatures, but not differentiable.
return ERR_CERT_AUTHORITY_INVALID;
case SEC_E_CERT_EXPIRED: // Schannel
case CERT_E_EXPIRED: // CryptoAPI
return ERR_CERT_DATE_INVALID;
case CRYPT_E_NO_REVOCATION_CHECK:
return ERR_CERT_NO_REVOCATION_MECHANISM;
case CRYPT_E_REVOCATION_OFFLINE:
return ERR_CERT_UNABLE_TO_CHECK_REVOCATION;
case CRYPT_E_REVOKED: // Schannel and CryptoAPI
return ERR_CERT_REVOKED;
case SEC_E_CERT_UNKNOWN:
case CERT_E_ROLE:
return ERR_CERT_INVALID;
case CERT_E_WRONG_USAGE:
// TODO(wtc): Should we add ERR_CERT_WRONG_USAGE?
return ERR_CERT_INVALID;
// We received an unexpected_message or illegal_parameter alert message
// from the server.
case SEC_E_ILLEGAL_MESSAGE:
return ERR_SSL_PROTOCOL_ERROR;
case SEC_E_ALGORITHM_MISMATCH:
return ERR_SSL_VERSION_OR_CIPHER_MISMATCH;
case SEC_E_INVALID_HANDLE:
return ERR_UNEXPECTED;
case SEC_E_OK:
return OK;
default:
LOG(WARNING) << "Unknown error " << err << " mapped to net::ERR_FAILED";
return ERR_FAILED;
}
}
// Map the errors in the chain_context->TrustStatus.dwErrorStatus returned by
// CertGetCertificateChain to our certificate status flags.
int MapCertChainErrorStatusToCertStatus(DWORD error_status) {
CertStatus cert_status = 0;
// We don't include CERT_TRUST_IS_NOT_TIME_NESTED because it's obsolete and
// we wouldn't consider it an error anyway
const DWORD kDateInvalidErrors = CERT_TRUST_IS_NOT_TIME_VALID |
CERT_TRUST_CTL_IS_NOT_TIME_VALID;
if (error_status & kDateInvalidErrors)
cert_status |= CERT_STATUS_DATE_INVALID;
const DWORD kAuthorityInvalidErrors = CERT_TRUST_IS_UNTRUSTED_ROOT |
CERT_TRUST_IS_EXPLICIT_DISTRUST |
CERT_TRUST_IS_PARTIAL_CHAIN;
if (error_status & kAuthorityInvalidErrors)
cert_status |= CERT_STATUS_AUTHORITY_INVALID;
if ((error_status & CERT_TRUST_REVOCATION_STATUS_UNKNOWN) &&
!(error_status & CERT_TRUST_IS_OFFLINE_REVOCATION))
cert_status |= CERT_STATUS_NO_REVOCATION_MECHANISM;
if (error_status & CERT_TRUST_IS_OFFLINE_REVOCATION)
cert_status |= CERT_STATUS_UNABLE_TO_CHECK_REVOCATION;
if (error_status & CERT_TRUST_IS_REVOKED)
cert_status |= CERT_STATUS_REVOKED;
const DWORD kWrongUsageErrors = CERT_TRUST_IS_NOT_VALID_FOR_USAGE |
CERT_TRUST_CTL_IS_NOT_VALID_FOR_USAGE;
if (error_status & kWrongUsageErrors) {
// TODO(wtc): Should we add CERT_STATUS_WRONG_USAGE?
cert_status |= CERT_STATUS_INVALID;
}
if (error_status & CERT_TRUST_IS_NOT_SIGNATURE_VALID) {
// Check for a signature that does not meet the OS criteria for strong
// signatures.
// Note: These checks may be more restrictive than the current weak key
// criteria implemented within CertVerifier, such as excluding SHA-1 or
// excluding RSA keys < 2048 bits. However, if the user has configured
// these more stringent checks, respect that configuration and err on the
// more restrictive criteria.
if (error_status & CERT_TRUST_HAS_WEAK_SIGNATURE) {
cert_status |= CERT_STATUS_WEAK_KEY;
} else {
cert_status |= CERT_STATUS_INVALID;
}
}
// The rest of the errors.
const DWORD kCertInvalidErrors =
CERT_TRUST_IS_CYCLIC |
CERT_TRUST_INVALID_EXTENSION |
CERT_TRUST_INVALID_POLICY_CONSTRAINTS |
CERT_TRUST_INVALID_BASIC_CONSTRAINTS |
CERT_TRUST_INVALID_NAME_CONSTRAINTS |
CERT_TRUST_CTL_IS_NOT_SIGNATURE_VALID |
CERT_TRUST_HAS_NOT_SUPPORTED_NAME_CONSTRAINT |
CERT_TRUST_HAS_NOT_DEFINED_NAME_CONSTRAINT |
CERT_TRUST_HAS_NOT_PERMITTED_NAME_CONSTRAINT |
CERT_TRUST_HAS_EXCLUDED_NAME_CONSTRAINT |
CERT_TRUST_NO_ISSUANCE_CHAIN_POLICY |
CERT_TRUST_HAS_NOT_SUPPORTED_CRITICAL_EXT;
if (error_status & kCertInvalidErrors)
cert_status |= CERT_STATUS_INVALID;
return cert_status;
}
// Returns true if any common name in the certificate's Subject field contains
// a NULL character.
bool CertSubjectCommonNameHasNull(PCCERT_CONTEXT cert) {
CRYPT_DECODE_PARA decode_para;
decode_para.cbSize = sizeof(decode_para);
decode_para.pfnAlloc = crypto::CryptAlloc;
decode_para.pfnFree = crypto::CryptFree;
CERT_NAME_INFO* name_info = nullptr;
DWORD name_info_size = 0;
BOOL rv;
rv = CryptDecodeObjectEx(X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
WINCRYPT_X509_NAME,
cert->pCertInfo->Subject.pbData,
cert->pCertInfo->Subject.cbData,
CRYPT_DECODE_ALLOC_FLAG | CRYPT_DECODE_NOCOPY_FLAG,
&decode_para,
&name_info,
&name_info_size);
if (rv) {
std::unique_ptr<CERT_NAME_INFO, base::FreeDeleter> scoped_name_info(
name_info);
// The Subject field may have multiple common names. According to the
// "PKI Layer Cake" paper, CryptoAPI uses every common name in the
// Subject field, so we inspect every common name.
//
// From RFC 5280:
// X520CommonName ::= CHOICE {
// teletexString TeletexString (SIZE (1..ub-common-name)),
// printableString PrintableString (SIZE (1..ub-common-name)),
// universalString UniversalString (SIZE (1..ub-common-name)),
// utf8String UTF8String (SIZE (1..ub-common-name)),
// bmpString BMPString (SIZE (1..ub-common-name)) }
//
// We also check IA5String and VisibleString.
for (DWORD i = 0; i < name_info->cRDN; ++i) {
PCERT_RDN rdn = &name_info->rgRDN[i];
for (DWORD j = 0; j < rdn->cRDNAttr; ++j) {
PCERT_RDN_ATTR rdn_attr = &rdn->rgRDNAttr[j];
if (strcmp(rdn_attr->pszObjId, szOID_COMMON_NAME) == 0) {
switch (rdn_attr->dwValueType) {
// After the CryptoAPI ASN.1 security vulnerabilities described in
// http://www.microsoft.com/technet/security/Bulletin/MS09-056.mspx
// were patched, we get CERT_RDN_ENCODED_BLOB for a common name
// that contains a NULL character.
case CERT_RDN_ENCODED_BLOB:
break;
// Array of 8-bit characters.
case CERT_RDN_PRINTABLE_STRING:
case CERT_RDN_TELETEX_STRING:
case CERT_RDN_IA5_STRING:
case CERT_RDN_VISIBLE_STRING:
for (DWORD k = 0; k < rdn_attr->Value.cbData; ++k) {
if (rdn_attr->Value.pbData[k] == '\0')
return true;
}
break;
// Array of 16-bit characters.
case CERT_RDN_BMP_STRING:
case CERT_RDN_UTF8_STRING: {
DWORD num_wchars = rdn_attr->Value.cbData / 2;
wchar_t* common_name =
reinterpret_cast<wchar_t*>(rdn_attr->Value.pbData);
for (DWORD k = 0; k < num_wchars; ++k) {
if (common_name[k] == L'\0')
return true;
}
break;
}
// Array of ints (32-bit).
case CERT_RDN_UNIVERSAL_STRING: {
DWORD num_ints = rdn_attr->Value.cbData / 4;
int* common_name =
reinterpret_cast<int*>(rdn_attr->Value.pbData);
for (DWORD k = 0; k < num_ints; ++k) {
if (common_name[k] == 0)
return true;
}
break;
}
default:
NOTREACHED();
break;
}
}
}
}
}
return false;
}
// Saves some information about the certificate chain |chain_context| in
// |*verify_result|. The caller MUST initialize |*verify_result| before
// calling this function.
void GetCertChainInfo(PCCERT_CHAIN_CONTEXT chain_context,
CertVerifyResult* verify_result) {
if (chain_context->cChain == 0)
return;
PCERT_SIMPLE_CHAIN first_chain = chain_context->rgpChain[0];
DWORD num_elements = first_chain->cElement;
PCERT_CHAIN_ELEMENT* element = first_chain->rgpElement;
PCCERT_CONTEXT verified_cert = nullptr;
std::vector<PCCERT_CONTEXT> verified_chain;
bool has_root_ca = num_elements > 1 &&
!(chain_context->TrustStatus.dwErrorStatus &
CERT_TRUST_IS_PARTIAL_CHAIN);
// Each chain starts with the end entity certificate (i = 0) and ends with
// either the root CA certificate or the last available intermediate. If a
// root CA certificate is present, do not inspect the signature algorithm of
// the root CA certificate because the signature on the trust anchor is not
// important.
if (has_root_ca) {
// If a full chain was constructed, regardless of whether it was trusted,
// don't inspect the root's signature algorithm.
num_elements -= 1;
}
for (DWORD i = 0; i < num_elements; ++i) {
PCCERT_CONTEXT cert = element[i]->pCertContext;
if (i == 0) {
verified_cert = cert;
} else {
verified_chain.push_back(cert);
}
}
if (verified_cert) {
// Add the root certificate, if present, as it was not added above.
if (has_root_ca)
verified_chain.push_back(element[num_elements]->pCertContext);
scoped_refptr<X509Certificate> verified_cert_with_chain =
x509_util::CreateX509CertificateFromCertContexts(verified_cert,
verified_chain);
if (verified_cert_with_chain)
verify_result->verified_cert = std::move(verified_cert_with_chain);
else
verify_result->cert_status |= CERT_STATUS_INVALID;
}
}
// Decodes the cert's certificatePolicies extension into a CERT_POLICIES_INFO
// structure and stores it in *output.
void GetCertPoliciesInfo(
PCCERT_CONTEXT cert,
std::unique_ptr<CERT_POLICIES_INFO, base::FreeDeleter>* output) {
PCERT_EXTENSION extension = CertFindExtension(szOID_CERT_POLICIES,
cert->pCertInfo->cExtension,
cert->pCertInfo->rgExtension);
if (!extension)
return;
CRYPT_DECODE_PARA decode_para;
decode_para.cbSize = sizeof(decode_para);
decode_para.pfnAlloc = crypto::CryptAlloc;
decode_para.pfnFree = crypto::CryptFree;
CERT_POLICIES_INFO* policies_info = nullptr;
DWORD policies_info_size = 0;
BOOL rv;
rv = CryptDecodeObjectEx(X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
szOID_CERT_POLICIES,
extension->Value.pbData,
extension->Value.cbData,
CRYPT_DECODE_ALLOC_FLAG | CRYPT_DECODE_NOCOPY_FLAG,
&decode_para,
&policies_info,
&policies_info_size);
if (rv)
output->reset(policies_info);
}
// Computes the SHA-256 hash of the SPKI of |cert| and stores it in |hash|,
// returning true. If an error occurs, returns false and leaves |hash|
// unmodified.
bool HashSPKI(PCCERT_CONTEXT cert, std::string* hash) {
base::StringPiece der_bytes(
reinterpret_cast<const char*>(cert->pbCertEncoded), cert->cbCertEncoded);
base::StringPiece spki;
if (!asn1::ExtractSPKIFromDERCert(der_bytes, &spki))
return false;
*hash = crypto::SHA256HashString(spki);
return true;
}
bool GetSubject(PCCERT_CONTEXT cert, base::StringPiece* out_subject) {
base::StringPiece der_bytes(
reinterpret_cast<const char*>(cert->pbCertEncoded), cert->cbCertEncoded);
return asn1::ExtractSubjectFromDERCert(der_bytes, out_subject);
}
enum CRLSetResult {
// Indicates an error happened while attempting to determine CRLSet status.
// For example, if the certificate's SPKI could not be extracted.
kCRLSetError,
// Indicates there is no fresh information about the certificate, or if the
// CRLSet has expired.
// In the case of certificate chains, this is only returned if the leaf
// certificate is not covered by the CRLSet; this is because some
// intermediates are fully covered, but after filtering, the issuer's CRL
// is empty and thus omitted from the CRLSet. Since online checking is
// performed for EV certificates when this status is returned, this would
// result in needless online lookups for certificates known not-revoked.
kCRLSetUnknown,
// Indicates that the certificate (or a certificate in the chain) has been
// revoked.
kCRLSetRevoked,
// The certificate (or certificate chain) has no revocations.
kCRLSetOk,
};
// Determines if |subject_cert| is revoked within |crl_set|,
// storing the SubjectPublicKeyInfo hash of |subject_cert| in
// |*previous_hash|.
//
// CRLSets store revocations by both SPKI and by the tuple of Issuer SPKI
// Hash & Serial. While |subject_cert| contains enough information to check
// for SPKI revocations, to determine the issuer's SPKI, either |issuer_cert|
// must be supplied, or the hash of the issuer's SPKI provided in
// |*previous_hash|. If |issuer_cert| is omitted, and |*previous_hash| is empty,
// only SPKI checks are performed.
//
// To avoid recomputing SPKI hashes, the hash of |subject_cert| is stored in
// |*previous_hash|. This allows chaining revocation checking, by starting
// at the root and iterating to the leaf, supplying |previous_hash| each time.
//
// In the event of a parsing error, |*previous_hash| is cleared, to prevent the
// wrong Issuer&Serial tuple from being used.
CRLSetResult CheckRevocationWithCRLSet(CRLSet* crl_set,
PCCERT_CONTEXT subject_cert,
PCCERT_CONTEXT issuer_cert,
std::string* previous_hash) {
DCHECK(crl_set);
DCHECK(subject_cert);
// Check to see if |subject_cert|'s SPKI or Subject is revoked.
std::string subject_hash;
base::StringPiece subject_name;
if (!HashSPKI(subject_cert, &subject_hash) ||
!GetSubject(subject_cert, &subject_name)) {
NOTREACHED(); // Indicates Windows accepted something irrecoverably bad.
previous_hash->clear();
return kCRLSetError;
}
if (crl_set->CheckSPKI(subject_hash) == CRLSet::REVOKED ||
crl_set->CheckSubject(subject_name, subject_hash) == CRLSet::REVOKED) {
return kCRLSetRevoked;
}
// If no issuer cert is provided, nor a hash of the issuer's SPKI, no
// further checks can be done.
if (!issuer_cert && previous_hash->empty()) {
previous_hash->swap(subject_hash);
return kCRLSetUnknown;
}
// Compute the subject's serial.
const CRYPT_INTEGER_BLOB* serial_blob =
&subject_cert->pCertInfo->SerialNumber;
std::unique_ptr<uint8_t[]> serial_bytes(new uint8_t[serial_blob->cbData]);
// The bytes of the serial number are stored little-endian.
// Note: While MSDN implies that bytes are stripped from this serial,
// they are not - only CertCompareIntegerBlob actually removes bytes.
for (DWORD j = 0; j < serial_blob->cbData; j++)
serial_bytes[j] = serial_blob->pbData[serial_blob->cbData - j - 1];
base::StringPiece serial(reinterpret_cast<const char*>(serial_bytes.get()),
serial_blob->cbData);
// Compute the issuer's hash. If it was provided (via previous_hash),
// use that; otherwise, compute it based on |issuer_cert|.
std::string issuer_hash_local;
std::string* issuer_hash = previous_hash;
if (issuer_hash->empty()) {
if (!HashSPKI(issuer_cert, &issuer_hash_local)) {
NOTREACHED(); // Indicates Windows accepted something irrecoverably bad.
previous_hash->clear();
return kCRLSetError;
}
issuer_hash = &issuer_hash_local;
}
// Look up by serial & issuer SPKI.
const CRLSet::Result result = crl_set->CheckSerial(serial, *issuer_hash);
if (result == CRLSet::REVOKED)
return kCRLSetRevoked;
previous_hash->swap(subject_hash);
if (result == CRLSet::GOOD)
return kCRLSetOk;
if (result == CRLSet::UNKNOWN)
return kCRLSetUnknown;
NOTREACHED();
return kCRLSetError;
}
// CheckChainRevocationWithCRLSet attempts to check each element of |chain|
// against |crl_set|. It returns:
// kCRLSetRevoked: if any element of the chain is known to have been revoked.
// kCRLSetUnknown: if there is no fresh information about the leaf
// certificate in the chain or if the CRLSet has expired.
//
// Only the leaf certificate is considered for coverage because some
// intermediates have CRLs with no revocations (after filtering) and
// those CRLs are pruned from the CRLSet at generation time. This means
// that some EV sites would otherwise take the hit of an OCSP lookup for
// no reason.
// kCRLSetOk: otherwise.
CRLSetResult CheckChainRevocationWithCRLSet(PCCERT_CHAIN_CONTEXT chain,
CRLSet* crl_set) {
if (chain->cChain == 0 || chain->rgpChain[0]->cElement == 0)
return kCRLSetOk;
PCERT_CHAIN_ELEMENT* elements = chain->rgpChain[0]->rgpElement;
DWORD num_elements = chain->rgpChain[0]->cElement;
bool had_error = false;
CRLSetResult result = kCRLSetError;
std::string issuer_spki_hash;
for (DWORD i = 0; i < num_elements; ++i) {
PCCERT_CONTEXT subject = elements[num_elements - i - 1]->pCertContext;
result =
CheckRevocationWithCRLSet(crl_set, subject, nullptr, &issuer_spki_hash);
if (result == kCRLSetRevoked)
return result;
if (result == kCRLSetError)
had_error = true;
}
if (had_error || crl_set->IsExpired())
return kCRLSetUnknown;
return result;
}
void AppendPublicKeyHashesAndUpdateKnownRoot(PCCERT_CHAIN_CONTEXT chain,
HashValueVector* hashes,
bool* known_root) {
if (chain->cChain == 0)
return;
PCERT_SIMPLE_CHAIN first_chain = chain->rgpChain[0];
PCERT_CHAIN_ELEMENT* const element = first_chain->rgpElement;
const DWORD num_elements = first_chain->cElement;
// Walk the chain in reverse, from the probable root to the known leaf, as
// an optimization for IsKnownRoot checks.
for (DWORD i = num_elements; i > 0; i--) {
PCCERT_CONTEXT cert = element[i - 1]->pCertContext;
base::StringPiece der_bytes(
reinterpret_cast<const char*>(cert->pbCertEncoded),
cert->cbCertEncoded);
base::StringPiece spki_bytes;
if (!asn1::ExtractSPKIFromDERCert(der_bytes, &spki_bytes))
continue;
HashValue sha256(HASH_VALUE_SHA256);
crypto::SHA256HashString(spki_bytes, sha256.data(), crypto::kSHA256Length);
hashes->push_back(sha256);
if (!*known_root) {
*known_root =
GetNetTrustAnchorHistogramIdForSPKI(sha256) != 0 || IsKnownRoot(cert);
}
}
// Reverse the hash list, such that it's ordered from leaf to root.
std::reverse(hashes->begin(), hashes->end());
}
// Returns true if the certificate is an extended-validation certificate.
//
// This function checks the certificatePolicies extensions of the
// certificates in the certificate chain according to Section 7 (pp. 11-12)
// of the EV Certificate Guidelines Version 1.0 at
// http://cabforum.org/EV_Certificate_Guidelines.pdf.
bool CheckEV(PCCERT_CHAIN_CONTEXT chain_context,
bool rev_checking_enabled,
const char* policy_oid) {
DCHECK_NE(static_cast<DWORD>(0), chain_context->cChain);
// If the cert doesn't match any of the policies, the
// CERT_TRUST_IS_NOT_VALID_FOR_USAGE bit (0x10) in
// chain_context->TrustStatus.dwErrorStatus is set.
DWORD error_status = chain_context->TrustStatus.dwErrorStatus;
if (!rev_checking_enabled) {
// If online revocation checking is disabled then we will have still
// requested that the revocation cache be checked. However, that will often
// cause the following two error bits to be set. These error bits mean that
// the local OCSP/CRL is stale or missing entries for these certificates.
// Since they are expected, we mask them away.
error_status &= ~(CERT_TRUST_IS_OFFLINE_REVOCATION |
CERT_TRUST_REVOCATION_STATUS_UNKNOWN);
}
if (!chain_context->cChain || error_status != CERT_TRUST_NO_ERROR)
return false;
// Check the end certificate simple chain (chain_context->rgpChain[0]).
// If the end certificate's certificatePolicies extension contains the
// EV policy OID of the root CA, return true.
PCERT_CHAIN_ELEMENT* element = chain_context->rgpChain[0]->rgpElement;
int num_elements = chain_context->rgpChain[0]->cElement;
if (num_elements < 2)
return false;
// Look up the EV policy OID of the root CA.
PCCERT_CONTEXT root_cert = element[num_elements - 1]->pCertContext;
SHA256HashValue fingerprint = x509_util::CalculateFingerprint256(root_cert);
EVRootCAMetadata* metadata = EVRootCAMetadata::GetInstance();
return metadata->HasEVPolicyOID(fingerprint, policy_oid);
}
// Custom revocation provider function that compares incoming certificates with
// those in CRLSets. This is called BEFORE the default CRL & OCSP handling
// is invoked (which is handled by the revocation provider function
// "CertDllVerifyRevocation" in cryptnet.dll)
BOOL WINAPI
CertDllVerifyRevocationWithCRLSet(DWORD encoding_type,
DWORD revocation_type,
DWORD num_contexts,
void* rgpvContext[],
DWORD flags,
PCERT_REVOCATION_PARA revocation_params,
PCERT_REVOCATION_STATUS revocation_status);
// Helper class that installs the CRLSet-based Revocation Provider as the
// default revocation provider. Because it is installed as a function address
// (meaning only scoped to the process, and not stored in the registry), it
// will be used before any registry-based providers, including Microsoft's
// default provider.
class RevocationInjector {
public:
CRLSet* GetCRLSet() { return thread_local_crlset.Get(); }
void SetCRLSet(CRLSet* crl_set) { thread_local_crlset.Set(crl_set); }
private:
friend struct base::LazyInstanceTraitsBase<RevocationInjector>;
RevocationInjector() {
const CRYPT_OID_FUNC_ENTRY kInterceptFunction[] = {
{CRYPT_DEFAULT_OID,
reinterpret_cast<void*>(&CertDllVerifyRevocationWithCRLSet)},
};
BOOL ok = CryptInstallOIDFunctionAddress(
nullptr, X509_ASN_ENCODING, CRYPT_OID_VERIFY_REVOCATION_FUNC,
base::size(kInterceptFunction), kInterceptFunction,
CRYPT_INSTALL_OID_FUNC_BEFORE_FLAG);
DCHECK(ok);
}
~RevocationInjector() {}
// As the revocation parameters passed to CertVerifyProc::VerifyInternal
// cannot be officially smuggled to the Revocation Provider
base::ThreadLocalPointer<CRLSet> thread_local_crlset;
};
// Leaky, as CertVerifyProc workers are themselves leaky.
base::LazyInstance<RevocationInjector>::Leaky g_revocation_injector =
LAZY_INSTANCE_INITIALIZER;
BOOL WINAPI
CertDllVerifyRevocationWithCRLSet(DWORD encoding_type,
DWORD revocation_type,
DWORD num_contexts,
void* rgpvContext[],
DWORD flags,
PCERT_REVOCATION_PARA revocation_params,
PCERT_REVOCATION_STATUS revocation_status) {
PCERT_CONTEXT* cert_contexts = reinterpret_cast<PCERT_CONTEXT*>(rgpvContext);
// The dummy CRLSet provider never returns that something is affirmatively
// *un*revoked, as this would disable other revocation providers from being
// checked for this certificate (much like an OCSP "Good" status would).
// Instead, it merely indicates that insufficient information existed to
// determine if the certificate was revoked (in the good case), or that a cert
// is affirmatively revoked in the event it appears within the CRLSet.
// Because of this, set up some basic bookkeeping for the results.
CHECK(revocation_status);
revocation_status->dwIndex = 0;
revocation_status->dwError = static_cast<DWORD>(CRYPT_E_NO_REVOCATION_CHECK);
revocation_status->dwReason = 0;
if (num_contexts == 0 || !cert_contexts[0]) {
SetLastError(static_cast<DWORD>(E_INVALIDARG));
return FALSE;
}
if ((GET_CERT_ENCODING_TYPE(encoding_type) != X509_ASN_ENCODING) ||
revocation_type != CERT_CONTEXT_REVOCATION_TYPE) {
SetLastError(static_cast<DWORD>(CRYPT_E_NO_REVOCATION_CHECK));
return FALSE;
}
// No revocation checking possible if there is no associated
// CRLSet.
CRLSet* crl_set = g_revocation_injector.Get().GetCRLSet();
if (!crl_set)
return FALSE;
// |revocation_params| is an optional structure; to make life simple and avoid
// the need to constantly check whether or not it was supplied, create a local
// copy. If the caller didn't supply anything, it will be empty; otherwise,
// it will be (non-owning) copies of the caller's original params.
CERT_REVOCATION_PARA local_params;
memset(&local_params, 0, sizeof(local_params));
if (revocation_params) {
DWORD bytes_to_copy = std::min(revocation_params->cbSize,
static_cast<DWORD>(sizeof(local_params)));
memcpy(&local_params, revocation_params, bytes_to_copy);
}
local_params.cbSize = sizeof(local_params);
PCERT_CONTEXT subject_cert = cert_contexts[0];
if ((flags & CERT_VERIFY_REV_CHAIN_FLAG) && num_contexts > 1) {
// Verifying a chain; first verify from the last certificate in the
// chain to the first, and then leave the last certificate (which
// is presumably self-issued, although it may simply be a trust
// anchor) as the |subject_cert| in order to scan for more
// revocations.
std::string issuer_hash;
PCCERT_CONTEXT issuer_cert = nullptr;
for (DWORD i = num_contexts; i > 0; --i) {
subject_cert = cert_contexts[i - 1];
if (!subject_cert) {
SetLastError(static_cast<DWORD>(E_INVALIDARG));
return FALSE;
}
CRLSetResult result = CheckRevocationWithCRLSet(
crl_set, subject_cert, issuer_cert, &issuer_hash);
if (result == kCRLSetRevoked) {
revocation_status->dwIndex = i - 1;
revocation_status->dwError = static_cast<DWORD>(CRYPT_E_REVOKED);
revocation_status->dwReason = CRL_REASON_UNSPECIFIED;
SetLastError(revocation_status->dwError);
return FALSE;
}
issuer_cert = subject_cert;
}
// Verified all certificates from the trust anchor to the leaf, and none
// were explicitly revoked. Now do a second pass to attempt to determine
// the issuer for cert_contexts[num_contexts - 1], so that the
// Issuer SPKI+Serial can be checked for that certificate.
//
// This code intentionally ignores the flag
subject_cert = cert_contexts[num_contexts - 1];
// Reset local_params.pIssuerCert, since it would contain the issuer
// for cert_contexts[0].
local_params.pIssuerCert = nullptr;
// Fixup the revocation index to point to this cert (in the event it is
// revoked). If it isn't revoked, this will be done undone later.
revocation_status->dwIndex = num_contexts - 1;
}
// Determine the issuer cert for the incoming cert
ScopedPCCERT_CONTEXT issuer_cert;
if (local_params.pIssuerCert &&
CryptVerifyCertificateSignatureEx(
NULL, subject_cert->dwCertEncodingType,
CRYPT_VERIFY_CERT_SIGN_SUBJECT_CERT, subject_cert,
CRYPT_VERIFY_CERT_SIGN_ISSUER_CERT,
const_cast<PCERT_CONTEXT>(local_params.pIssuerCert), 0, nullptr)) {
// Caller has already supplied the issuer cert via the revocation params;
// just use that.
issuer_cert.reset(
CertDuplicateCertificateContext(local_params.pIssuerCert));
} else if (CertCompareCertificateName(subject_cert->dwCertEncodingType,
&subject_cert->pCertInfo->Subject,
&subject_cert->pCertInfo->Issuer) &&
CryptVerifyCertificateSignatureEx(
NULL, subject_cert->dwCertEncodingType,
CRYPT_VERIFY_CERT_SIGN_SUBJECT_CERT, subject_cert,
CRYPT_VERIFY_CERT_SIGN_ISSUER_CERT, subject_cert, 0,
nullptr)) {
// Certificate is self-signed; use it as its own issuer.
issuer_cert.reset(CertDuplicateCertificateContext(subject_cert));
} else {
// Scan the caller-supplied stores first, to try and find the issuer cert.
for (DWORD i = 0; i < local_params.cCertStore && !issuer_cert; ++i) {
PCCERT_CONTEXT previous_cert = nullptr;
for (;;) {
DWORD store_search_flags = CERT_STORE_SIGNATURE_FLAG;
previous_cert = CertGetIssuerCertificateFromStore(
local_params.rgCertStore[i], subject_cert, previous_cert,
&store_search_flags);
if (!previous_cert)
break;
// If a cert is found and meets the criteria, the flag will be reset to
// zero. Thus NOT having the bit set is equivalent to having found a
// matching certificate.
if (!(store_search_flags & CERT_STORE_SIGNATURE_FLAG)) {
// No need to dupe; reference is held.
issuer_cert.reset(previous_cert);
break;
}
}
if (issuer_cert)
break;
if (GetLastError() == static_cast<DWORD>(CRYPT_E_SELF_SIGNED)) {
issuer_cert.reset(CertDuplicateCertificateContext(subject_cert));
break;
}
}
// At this point, the Microsoft provider opens up the "CA", "Root", and
// "SPC" stores to search for the issuer certificate, if not found in the
// caller-supplied stores. It is unclear whether that is necessary here.
}
if (!issuer_cert) {
// Rather than return CRYPT_E_NO_REVOCATION_CHECK (indicating everything
// is fine to try the next provider), return CRYPT_E_REVOCATION_OFFLINE.
// This propogates up to the caller as an error while checking revocation,
// which is the desired intent if there are certificates that cannot
// be checked.
revocation_status->dwIndex = 0;
revocation_status->dwError = static_cast<DWORD>(CRYPT_E_REVOCATION_OFFLINE);
SetLastError(revocation_status->dwError);
return FALSE;
}
std::string unused;
CRLSetResult result = CheckRevocationWithCRLSet(crl_set, subject_cert,
issuer_cert.get(), &unused);
if (result == kCRLSetRevoked) {
revocation_status->dwError = static_cast<DWORD>(CRYPT_E_REVOKED);
revocation_status->dwReason = CRL_REASON_UNSPECIFIED;
SetLastError(revocation_status->dwError);
return FALSE;
}
// The result is ALWAYS FALSE in order to allow the next revocation provider
// a chance to examine. The only difference is whether or not an error is
// indicated via dwError (and SetLastError()).
// Reset the error index so that Windows does not believe this code has
// examined the entire chain and found no issues until the last cert (thus
// skipping other revocation providers).
revocation_status->dwIndex = 0;
return FALSE;
}
class ScopedThreadLocalCRLSet {
public:
explicit ScopedThreadLocalCRLSet(CRLSet* crl_set) {
g_revocation_injector.Get().SetCRLSet(crl_set);
}
~ScopedThreadLocalCRLSet() { g_revocation_injector.Get().SetCRLSet(nullptr); }
};
} // namespace
CertVerifyProcWin::CertVerifyProcWin() {}
CertVerifyProcWin::~CertVerifyProcWin() {}
bool CertVerifyProcWin::SupportsAdditionalTrustAnchors() const {
return false;
}
int CertVerifyProcWin::VerifyInternal(
X509Certificate* cert,
const std::string& hostname,
const std::string& ocsp_response,
const std::string& sct_list,
int flags,
CRLSet* crl_set,
const CertificateList& additional_trust_anchors,
CertVerifyResult* verify_result) {
// Ensure the Revocation Provider has been installed and configured for this
// CRLSet.
ScopedThreadLocalCRLSet thread_local_crlset(crl_set);
ScopedPCCERT_CONTEXT cert_list = x509_util::CreateCertContextWithChain(
cert, x509_util::InvalidIntermediateBehavior::kIgnore);
if (!cert_list) {
verify_result->cert_status |= CERT_STATUS_INVALID;
return ERR_CERT_INVALID;
}
// Build and validate certificate chain.
CERT_CHAIN_PARA chain_para;
memset(&chain_para, 0, sizeof(chain_para));
chain_para.cbSize = sizeof(chain_para);
// ExtendedKeyUsage.
// We still need to request szOID_SERVER_GATED_CRYPTO and szOID_SGC_NETSCAPE
// today because some certificate chains need them. IE also requests these
// two usages.
static const LPCSTR usage[] = {
szOID_PKIX_KP_SERVER_AUTH,
szOID_SERVER_GATED_CRYPTO,
szOID_SGC_NETSCAPE
};
chain_para.RequestedUsage.dwType = USAGE_MATCH_TYPE_OR;
chain_para.RequestedUsage.Usage.cUsageIdentifier = base::size(usage);
chain_para.RequestedUsage.Usage.rgpszUsageIdentifier =
const_cast<LPSTR*>(usage);
// Get the certificatePolicies extension of the certificate.
std::unique_ptr<CERT_POLICIES_INFO, base::FreeDeleter> policies_info;
LPSTR ev_policy_oid = nullptr;
GetCertPoliciesInfo(cert_list.get(), &policies_info);
if (policies_info) {
EVRootCAMetadata* metadata = EVRootCAMetadata::GetInstance();
for (DWORD i = 0; i < policies_info->cPolicyInfo; ++i) {
LPSTR policy_oid = policies_info->rgPolicyInfo[i].pszPolicyIdentifier;
if (metadata->IsEVPolicyOID(policy_oid)) {
ev_policy_oid = policy_oid;
chain_para.RequestedIssuancePolicy.dwType = USAGE_MATCH_TYPE_AND;
chain_para.RequestedIssuancePolicy.Usage.cUsageIdentifier = 1;
chain_para.RequestedIssuancePolicy.Usage.rgpszUsageIdentifier =
&ev_policy_oid;
// De-prioritize the CA/Browser forum Extended Validation policy
// (2.23.140.1.1). See https://crbug.com/705285.
if (!EVRootCAMetadata::IsCaBrowserForumEvOid(ev_policy_oid))
break;
}
}
}
// Revocation checking is always enabled, in order to enable CRLSets to be
// evaluated as part of a revocation provider. However, when the caller did
// not explicitly request revocation checking (which is to say, online
// revocation checking), then only enable cached results. This disables OCSP
// and CRL fetching, but still allows the revocation provider to be called.
// Note: The root cert is also checked for revocation status, so that CRLSets
// will cover revoked SPKIs.
DWORD chain_flags = CERT_CHAIN_REVOCATION_CHECK_CHAIN;
bool rev_checking_enabled = (flags & VERIFY_REV_CHECKING_ENABLED);
if (rev_checking_enabled) {
verify_result->cert_status |= CERT_STATUS_REV_CHECKING_ENABLED;
} else {
chain_flags |= CERT_CHAIN_REVOCATION_CHECK_CACHE_ONLY;
}
// By default, use the default HCERTCHAINENGINE (aka HCCE_CURRENT_USER). When
// running tests, use a dynamic HCERTCHAINENGINE. All of the status and cache
// of verified certificates and chains is tied to the HCERTCHAINENGINE. As
// each invocation may have changed the set of known roots, invalidate the
// cache between runs.
//
// This is not the most efficient means of doing so; it's possible to mark the
// Root store used by TestRootCerts as changed, via CertControlStore with the
// CERT_STORE_CTRL_NOTIFY_CHANGE / CERT_STORE_CTRL_RESYNC, but that's more
// complexity for what is test-only code.
ScopedHCERTCHAINENGINE chain_engine(NULL);
if (TestRootCerts::HasInstance())
chain_engine.reset(TestRootCerts::GetInstance()->GetChainEngine());
// Add stapled OCSP response data, which will be preferred over online checks
// and used when in cache-only mode.
if (!ocsp_response.empty()) {
CRYPT_DATA_BLOB ocsp_response_blob;
ocsp_response_blob.cbData = base::checked_cast<DWORD>(ocsp_response.size());
ocsp_response_blob.pbData =
reinterpret_cast<BYTE*>(const_cast<char*>(ocsp_response.data()));
CertSetCertificateContextProperty(
cert_list.get(), CERT_OCSP_RESPONSE_PROP_ID,
CERT_SET_PROPERTY_IGNORE_PERSIST_ERROR_FLAG, &ocsp_response_blob);
}
CERT_STRONG_SIGN_SERIALIZED_INFO strong_signed_info;
memset(&strong_signed_info, 0, sizeof(strong_signed_info));
strong_signed_info.dwFlags = 0; // Don't check OCSP or CRL signatures.
// Note that the following two configurations result in disabling support for
// any CNG-added algorithms, which may result in some disruption for internal
// PKI operations that use national forms of crypto (e.g. GOST). However, the
// fallback mechanism for this (to support SHA-1 chains) will re-enable them,
// so they should continue to work - just with added latency.
wchar_t hash_algs[] =
L"RSA/SHA256;RSA/SHA384;RSA/SHA512;"
L"ECDSA/SHA256;ECDSA/SHA384;ECDSA/SHA512";
strong_signed_info.pwszCNGSignHashAlgids = hash_algs;
// RSA-1024 bit support is intentionally enabled here. More investigation is
// needed to determine if setting CERT_STRONG_SIGN_DISABLE_END_CHECK_FLAG in
// the dwStrongSignFlags of |chain_para| would allow the ability to disable
// support for intermediates/roots < 2048-bits, while still ensuring that
// end-entity certs signed with SHA-1 are flagged/rejected.
wchar_t key_sizes[] = L"RSA/1024;ECDSA/256";
strong_signed_info.pwszCNGPubKeyMinBitLengths = key_sizes;
CERT_STRONG_SIGN_PARA strong_sign_params;
memset(&strong_sign_params, 0, sizeof(strong_sign_params));
strong_sign_params.cbSize = sizeof(strong_sign_params);
strong_sign_params.dwInfoChoice = CERT_STRONG_SIGN_SERIALIZED_INFO_CHOICE;
strong_sign_params.pSerializedInfo = &strong_signed_info;
chain_para.dwStrongSignFlags = 0;
chain_para.pStrongSignPara = &strong_sign_params;
PCCERT_CHAIN_CONTEXT chain_context = nullptr;
// First, try to verify with strong signing enabled. If this fails, or if the
// chain is rejected, then clear it from |chain_para| so that all subsequent
// calls will use the fallback path.
BOOL chain_result =
CertGetCertificateChain(chain_engine, cert_list.get(),
nullptr, // current system time
cert_list->hCertStore, &chain_para, chain_flags,
nullptr, // reserved
&chain_context);
if (chain_result && chain_context &&
(chain_context->TrustStatus.dwErrorStatus &
(CERT_TRUST_HAS_WEAK_SIGNATURE | CERT_TRUST_IS_NOT_SIGNATURE_VALID))) {
// The attempt to verify with strong-sign (only SHA-2) failed, so fall back
// to disabling it. This will allow SHA-1 chains to be returned, which will
// then be subsequently signalled as weak if necessary.
CertFreeCertificateChain(chain_context);
chain_context = nullptr;
chain_para.pStrongSignPara = nullptr;
chain_para.dwStrongSignFlags = 0;
chain_result =
CertGetCertificateChain(chain_engine, cert_list.get(),
nullptr, // current system time
cert_list->hCertStore, &chain_para, chain_flags,
nullptr, // reserved
&chain_context);
}
if (!chain_result) {
verify_result->cert_status |= CERT_STATUS_INVALID;
return MapSecurityError(GetLastError());
}
// Perform a second check with CRLSets. Although the Revocation Provider
// should have prevented invalid paths from being built, the behaviour and
// timing of how a Revocation Provider is invoked is not well documented. This
// is just defense in depth.
CRLSetResult crl_set_result =
CheckChainRevocationWithCRLSet(chain_context, crl_set);
if (crl_set_result == kCRLSetRevoked) {
verify_result->cert_status |= CERT_STATUS_REVOKED;
} else if (crl_set_result == kCRLSetUnknown && !rev_checking_enabled &&
ev_policy_oid) {
// We don't have fresh information about this chain from the CRLSet and
// it's probably an EV certificate. Retry with online revocation checking.
rev_checking_enabled = true;
chain_flags &= ~CERT_CHAIN_REVOCATION_CHECK_CACHE_ONLY;
verify_result->cert_status |= CERT_STATUS_REV_CHECKING_ENABLED;
CertFreeCertificateChain(chain_context);
if (!CertGetCertificateChain(chain_engine, cert_list.get(),
nullptr, // current system time
cert_list->hCertStore, &chain_para,
chain_flags,
nullptr, // reserved
&chain_context)) {
verify_result->cert_status |= CERT_STATUS_INVALID;
return MapSecurityError(GetLastError());
}
}
if (chain_context->TrustStatus.dwErrorStatus &
CERT_TRUST_IS_NOT_VALID_FOR_USAGE) {
// Could not verify the cert with the EV policy. Remove the EV policy and
// try again.
ev_policy_oid = nullptr;
chain_para.RequestedIssuancePolicy.Usage.cUsageIdentifier = 0;
chain_para.RequestedIssuancePolicy.Usage.rgpszUsageIdentifier = nullptr;
CertFreeCertificateChain(chain_context);
if (!CertGetCertificateChain(chain_engine, cert_list.get(),
nullptr, // current system time
cert_list->hCertStore, &chain_para,
chain_flags,
nullptr, // reserved
&chain_context)) {
verify_result->cert_status |= CERT_STATUS_INVALID;
return MapSecurityError(GetLastError());
}
}
CertVerifyResult temp_verify_result = *verify_result;
GetCertChainInfo(chain_context, verify_result);
if (!verify_result->is_issued_by_known_root &&
(flags & VERIFY_REV_CHECKING_REQUIRED_LOCAL_ANCHORS)) {
*verify_result = temp_verify_result;
rev_checking_enabled = true;
verify_result->cert_status |= CERT_STATUS_REV_CHECKING_ENABLED;
chain_flags &= ~CERT_CHAIN_REVOCATION_CHECK_CACHE_ONLY;
CertFreeCertificateChain(chain_context);
if (!CertGetCertificateChain(chain_engine, cert_list.get(),
nullptr, // current system time
cert_list->hCertStore, &chain_para,
chain_flags,
nullptr, // reserved
&chain_context)) {
verify_result->cert_status |= CERT_STATUS_INVALID;
return MapSecurityError(GetLastError());
}
GetCertChainInfo(chain_context, verify_result);
}
ScopedPCCERT_CHAIN_CONTEXT scoped_chain_context(chain_context);
verify_result->cert_status |= MapCertChainErrorStatusToCertStatus(
chain_context->TrustStatus.dwErrorStatus);
// Flag certificates that have a Subject common name with a NULL character.
if (CertSubjectCommonNameHasNull(cert_list.get()))
verify_result->cert_status |= CERT_STATUS_INVALID;
base::string16 hostname16 = base::ASCIIToUTF16(hostname);
SSL_EXTRA_CERT_CHAIN_POLICY_PARA extra_policy_para;
memset(&extra_policy_para, 0, sizeof(extra_policy_para));
extra_policy_para.cbSize = sizeof(extra_policy_para);
extra_policy_para.dwAuthType = AUTHTYPE_SERVER;
// Certificate name validation happens separately, later, using an internal
// routine that has better support for RFC 6125 name matching.
extra_policy_para.fdwChecks =
0x00001000; // SECURITY_FLAG_IGNORE_CERT_CN_INVALID
extra_policy_para.pwszServerName = base::as_writable_wcstr(hostname16);
CERT_CHAIN_POLICY_PARA policy_para;
memset(&policy_para, 0, sizeof(policy_para));
policy_para.cbSize = sizeof(policy_para);
policy_para.dwFlags = 0;
policy_para.pvExtraPolicyPara = &extra_policy_para;
CERT_CHAIN_POLICY_STATUS policy_status;
memset(&policy_status, 0, sizeof(policy_status));
policy_status.cbSize = sizeof(policy_status);
if (!CertVerifyCertificateChainPolicy(
CERT_CHAIN_POLICY_SSL,
chain_context,
&policy_para,
&policy_status)) {
return MapSecurityError(GetLastError());
}
if (policy_status.dwError) {
verify_result->cert_status |= MapNetErrorToCertStatus(
MapSecurityError(policy_status.dwError));
}
// Mask off revocation checking failures unless hard-fail revocation checking
// for local anchors is enabled and the chain is issued by a local root.
// (CheckEV will still check chain_context->TrustStatus.dwErrorStatus directly
// so as to not mark as EV if revocation information was not available.)
if (!(!verify_result->is_issued_by_known_root &&
(flags & VERIFY_REV_CHECKING_REQUIRED_LOCAL_ANCHORS))) {
verify_result->cert_status &= ~(CERT_STATUS_NO_REVOCATION_MECHANISM |
CERT_STATUS_UNABLE_TO_CHECK_REVOCATION);
}
AppendPublicKeyHashesAndUpdateKnownRoot(
chain_context, &verify_result->public_key_hashes,
&verify_result->is_issued_by_known_root);
if (IsCertStatusError(verify_result->cert_status))
return MapCertStatusToNetError(verify_result->cert_status);
if (ev_policy_oid &&
CheckEV(chain_context, rev_checking_enabled, ev_policy_oid)) {
verify_result->cert_status |= CERT_STATUS_IS_EV;
}
LogNameNormalizationMetrics(".Win", verify_result->verified_cert.get(),
verify_result->is_issued_by_known_root);
return OK;
}
} // namespace net