blob: 4dd8715c686b024ec6e4437eaec3d42370631bf4 [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_mac.h"
#include <CommonCrypto/CommonDigest.h>
#include <CoreServices/CoreServices.h>
#include <Security/Security.h>
#include <string>
#include <vector>
#include "base/logging.h"
#include "base/mac/mac_logging.h"
#include "base/mac/mac_util.h"
#include "base/mac/scoped_cftyperef.h"
#include "base/strings/string_piece.h"
#include "base/synchronization/lock.h"
#include "crypto/mac_security_services_lock.h"
#include "crypto/sha2.h"
#include "net/base/hash_value.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/internal/certificate_policies.h"
#include "net/cert/internal/parsed_certificate.h"
#include "net/cert/known_roots_mac.h"
#include "net/cert/test_keychain_search_list_mac.h"
#include "net/cert/test_root_certs.h"
#include "net/cert/x509_certificate.h"
#include "net/cert/x509_util.h"
#include "net/cert/x509_util_ios_and_mac.h"
#include "net/cert/x509_util_mac.h"
// CSSM functions are deprecated as of OSX 10.7, but have no replacement.
// https://bugs.chromium.org/p/chromium/issues/detail?id=590914#c1
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
using base::ScopedCFTypeRef;
namespace net {
namespace {
typedef OSStatus (*SecTrustCopyExtendedResultFuncPtr)(SecTrustRef,
CFDictionaryRef*);
int NetErrorFromOSStatus(OSStatus status) {
switch (status) {
case noErr:
return OK;
case errSecNotAvailable:
case errSecNoCertificateModule:
case errSecNoPolicyModule:
return ERR_NOT_IMPLEMENTED;
case errSecAuthFailed:
return ERR_ACCESS_DENIED;
default: {
OSSTATUS_LOG(ERROR, status) << "Unknown error mapped to ERR_FAILED";
return ERR_FAILED;
}
}
}
CertStatus CertStatusFromOSStatus(OSStatus status) {
switch (status) {
case noErr:
return 0;
case CSSMERR_TP_INVALID_ANCHOR_CERT:
case CSSMERR_TP_NOT_TRUSTED:
case CSSMERR_TP_INVALID_CERT_AUTHORITY:
return CERT_STATUS_AUTHORITY_INVALID;
case CSSMERR_TP_CERT_EXPIRED:
case CSSMERR_TP_CERT_NOT_VALID_YET:
// "Expired" and "not yet valid" collapse into a single status.
return CERT_STATUS_DATE_INVALID;
case CSSMERR_TP_CERT_REVOKED:
case CSSMERR_TP_CERT_SUSPENDED:
return CERT_STATUS_REVOKED;
case CSSMERR_APPLETP_HOSTNAME_MISMATCH:
return CERT_STATUS_COMMON_NAME_INVALID;
case CSSMERR_APPLETP_CRL_NOT_FOUND:
case CSSMERR_APPLETP_OCSP_UNAVAILABLE:
return CERT_STATUS_NO_REVOCATION_MECHANISM;
case CSSMERR_APPLETP_INCOMPLETE_REVOCATION_CHECK:
// Starting with later 10.12 versions,
// CSSMERR_APPLETP_INCOMPLETE_REVOCATION_CHECK is a catch-all code for
// failures to check revocation status.
// However, on pre-10.12 versions, it would also be used on revocation
// failures. (CERT_STATUS_NO_REVOCATION_MECHANISM isn't really right
// there either, but that's what the old code has, and it just gets
// masked off later so has no actual effect.)
return base::mac::IsAtLeastOS10_12()
? CERT_STATUS_UNABLE_TO_CHECK_REVOCATION
: CERT_STATUS_NO_REVOCATION_MECHANISM;
case CSSMERR_APPLETP_CRL_EXPIRED:
case CSSMERR_APPLETP_CRL_NOT_VALID_YET:
case CSSMERR_APPLETP_CRL_SERVER_DOWN:
case CSSMERR_APPLETP_CRL_NOT_TRUSTED:
case CSSMERR_APPLETP_CRL_INVALID_ANCHOR_CERT:
case CSSMERR_APPLETP_CRL_POLICY_FAIL:
case CSSMERR_APPLETP_OCSP_BAD_RESPONSE:
case CSSMERR_APPLETP_OCSP_BAD_REQUEST:
case CSSMERR_APPLETP_OCSP_STATUS_UNRECOGNIZED:
case CSSMERR_APPLETP_NETWORK_FAILURE:
case CSSMERR_APPLETP_OCSP_NOT_TRUSTED:
case CSSMERR_APPLETP_OCSP_INVALID_ANCHOR_CERT:
case CSSMERR_APPLETP_OCSP_SIG_ERROR:
case CSSMERR_APPLETP_OCSP_NO_SIGNER:
case CSSMERR_APPLETP_OCSP_RESP_MALFORMED_REQ:
case CSSMERR_APPLETP_OCSP_RESP_INTERNAL_ERR:
case CSSMERR_APPLETP_OCSP_RESP_TRY_LATER:
case CSSMERR_APPLETP_OCSP_RESP_SIG_REQUIRED:
case CSSMERR_APPLETP_OCSP_RESP_UNAUTHORIZED:
case CSSMERR_APPLETP_OCSP_NONCE_MISMATCH:
// We asked for a revocation check, but didn't get it.
return CERT_STATUS_UNABLE_TO_CHECK_REVOCATION;
case CSSMERR_APPLETP_SSL_BAD_EXT_KEY_USE:
// TODO(wtc): Should we add CERT_STATUS_WRONG_USAGE?
return CERT_STATUS_INVALID;
case CSSMERR_APPLETP_CRL_BAD_URI:
case CSSMERR_APPLETP_IDP_FAIL:
return CERT_STATUS_INVALID;
case CSSMERR_CSP_UNSUPPORTED_KEY_SIZE:
// Mapping UNSUPPORTED_KEY_SIZE to CERT_STATUS_WEAK_KEY is not strictly
// accurate, as the error may have been returned due to a key size
// that exceeded the maximum supported. However, within
// CertVerifyProcMac::VerifyInternal(), this code should only be
// encountered as a certificate status code, and only when the key size
// is smaller than the minimum required (1024 bits).
return CERT_STATUS_WEAK_KEY;
default: {
// Failure was due to something Chromium doesn't define a
// specific status for (such as basic constraints violation, or
// unknown critical extension)
OSSTATUS_LOG(WARNING, status)
<< "Unknown error mapped to CERT_STATUS_INVALID";
return CERT_STATUS_INVALID;
}
}
}
// Creates a series of SecPolicyRefs to be added to a SecTrustRef used to
// validate a certificate for an SSL server. |flags| is a bitwise-OR of
// VerifyFlags that can further alter how trust is validated, such as how
// revocation is checked. If successful, returns noErr, and stores the
// resultant array of SecPolicyRefs in |policies|.
OSStatus CreateTrustPolicies(int flags, ScopedCFTypeRef<CFArrayRef>* policies) {
ScopedCFTypeRef<CFMutableArrayRef> local_policies(
CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks));
if (!local_policies)
return memFullErr;
SecPolicyRef ssl_policy;
OSStatus status =
x509_util::CreateSSLServerPolicy(std::string(), &ssl_policy);
if (status)
return status;
CFArrayAppendValue(local_policies, ssl_policy);
CFRelease(ssl_policy);
// Explicitly add revocation policies, in order to override system
// revocation checking policies and instead respect the application-level
// revocation preference.
status = x509_util::CreateRevocationPolicies(
(flags & CertVerifier::VERIFY_REV_CHECKING_ENABLED), local_policies);
if (status)
return status;
policies->reset(local_policies.release());
return noErr;
}
// Stores the constructed certificate chain |cert_chain| into
// |*verify_result|. |cert_chain| must not be empty.
void CopyCertChainToVerifyResult(CFArrayRef cert_chain,
CertVerifyResult* verify_result) {
DCHECK_LT(0, CFArrayGetCount(cert_chain));
SecCertificateRef verified_cert = NULL;
std::vector<SecCertificateRef> verified_chain;
for (CFIndex i = 0, count = CFArrayGetCount(cert_chain); i < count; ++i) {
SecCertificateRef chain_cert = reinterpret_cast<SecCertificateRef>(
const_cast<void*>(CFArrayGetValueAtIndex(cert_chain, i)));
if (i == 0) {
verified_cert = chain_cert;
} else {
verified_chain.push_back(chain_cert);
}
}
if (!verified_cert) {
NOTREACHED();
verify_result->cert_status |= CERT_STATUS_INVALID;
return;
}
scoped_refptr<X509Certificate> verified_cert_with_chain =
x509_util::CreateX509CertificateFromSecCertificate(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;
}
// Returns true if the certificate uses MD2, MD4, MD5, or SHA1, and false
// otherwise. A return of false also includes the case where the signature
// algorithm couldn't be conclusively labeled as weak.
bool CertUsesWeakHash(SecCertificateRef cert_handle) {
x509_util::CSSMCachedCertificate cached_cert;
OSStatus status = cached_cert.Init(cert_handle);
if (status)
return false;
x509_util::CSSMFieldValue signature_field;
status =
cached_cert.GetField(&CSSMOID_X509V1SignatureAlgorithm, &signature_field);
if (status || !signature_field.field())
return false;
const CSSM_X509_ALGORITHM_IDENTIFIER* sig_algorithm =
signature_field.GetAs<CSSM_X509_ALGORITHM_IDENTIFIER>();
if (!sig_algorithm)
return false;
const CSSM_OID* alg_oid = &sig_algorithm->algorithm;
return (x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_MD2WithRSA) ||
x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_MD4WithRSA) ||
x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_MD5WithRSA) ||
x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_SHA1WithRSA) ||
x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_SHA1WithRSA_OIW) ||
x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_SHA1WithDSA) ||
x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_SHA1WithDSA_CMS) ||
x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_SHA1WithDSA_JDK) ||
x509_util::CSSMOIDEqual(alg_oid, &CSSMOID_ECDSA_WithSHA1));
}
// Returns true if the intermediates (excluding trusted certificates) use a
// weak hashing algorithm, but the target does not use a weak hash.
bool IsWeakChainBasedOnHashingAlgorithms(
CFArrayRef cert_chain,
CSSM_TP_APPLE_EVIDENCE_INFO* chain_info) {
DCHECK_LT(0, CFArrayGetCount(cert_chain));
bool intermediates_contain_weak_hash = false;
bool leaf_uses_weak_hash = false;
for (CFIndex i = 0, count = CFArrayGetCount(cert_chain); i < count; ++i) {
SecCertificateRef chain_cert = reinterpret_cast<SecCertificateRef>(
const_cast<void*>(CFArrayGetValueAtIndex(cert_chain, i)));
if ((chain_info[i].StatusBits & CSSM_CERT_STATUS_IS_IN_ANCHORS) ||
(chain_info[i].StatusBits & CSSM_CERT_STATUS_IS_ROOT)) {
// The current certificate is either in the user's trusted store or is
// a root (self-signed) certificate. Ignore the signature algorithm for
// these certificates, as it is meaningless for security. We allow
// self-signed certificates (i == 0 & IS_ROOT), since we accept that
// any security assertions by such a cert are inherently meaningless.
continue;
}
if (CertUsesWeakHash(chain_cert)) {
if (i == 0) {
leaf_uses_weak_hash = true;
} else {
intermediates_contain_weak_hash = true;
}
}
}
return !leaf_uses_weak_hash && intermediates_contain_weak_hash;
}
// Checks if |*cert| has a Certificate Policies extension containing either
// of |ev_policy_oid| or anyPolicy.
bool HasPolicyOrAnyPolicy(const ParsedCertificate* cert,
const der::Input& ev_policy_oid) {
if (!cert->has_policy_oids())
return false;
for (const der::Input& policy_oid : cert->policy_oids()) {
if (policy_oid == ev_policy_oid || policy_oid == AnyPolicy())
return true;
}
return false;
}
// Looks for known EV policy OIDs in |cert_input|, if one is found it will be
// stored in |*ev_policy_oid| as a DER-encoded OID value (no tag or length).
void GetCandidateEVPolicy(const X509Certificate* cert_input,
std::string* ev_policy_oid) {
ev_policy_oid->clear();
scoped_refptr<ParsedCertificate> cert(ParsedCertificate::Create(
x509_util::DupCryptoBuffer(cert_input->cert_buffer()), {}, nullptr));
if (!cert)
return;
if (!cert->has_policy_oids())
return;
EVRootCAMetadata* metadata = EVRootCAMetadata::GetInstance();
for (const der::Input& policy_oid : cert->policy_oids()) {
if (metadata->IsEVPolicyOID(policy_oid)) {
*ev_policy_oid = policy_oid.AsString();
// De-prioritize the CA/Browser forum Extended Validation policy
// (2.23.140.1.1). See crbug.com/705285.
if (!EVRootCAMetadata::IsCaBrowserForumEvOid(policy_oid))
break;
}
}
}
// Checks that the certificate chain of |cert| has policies consistent with
// |ev_policy_oid_string|. The leaf is not checked, as it is assumed that is
// where the policy came from.
bool CheckCertChainEV(const X509Certificate* cert,
const std::string& ev_policy_oid_string) {
der::Input ev_policy_oid(&ev_policy_oid_string);
const std::vector<bssl::UniquePtr<CRYPTO_BUFFER>>& cert_chain =
cert->intermediate_buffers();
// Root should have matching policy in EVRootCAMetadata.
if (cert_chain.empty())
return false;
SHA256HashValue fingerprint =
X509Certificate::CalculateFingerprint256(cert_chain.back().get());
EVRootCAMetadata* metadata = EVRootCAMetadata::GetInstance();
if (!metadata->HasEVPolicyOID(fingerprint, ev_policy_oid))
return false;
// Intermediates should have Certificate Policies extension with the EV policy
// or AnyPolicy.
for (size_t i = 0; i < cert_chain.size() - 1; ++i) {
scoped_refptr<ParsedCertificate> intermediate_cert(
ParsedCertificate::Create(
x509_util::DupCryptoBuffer(cert_chain[i].get()), {}, nullptr));
if (!intermediate_cert)
return false;
if (!HasPolicyOrAnyPolicy(intermediate_cert.get(), ev_policy_oid))
return false;
}
return true;
}
void AppendPublicKeyHashes(CFArrayRef chain,
HashValueVector* hashes) {
const CFIndex n = CFArrayGetCount(chain);
for (CFIndex i = 0; i < n; i++) {
SecCertificateRef cert = reinterpret_cast<SecCertificateRef>(
const_cast<void*>(CFArrayGetValueAtIndex(chain, i)));
CSSM_DATA cert_data;
OSStatus err = SecCertificateGetData(cert, &cert_data);
DCHECK_EQ(err, noErr);
base::StringPiece der_bytes(reinterpret_cast<const char*>(cert_data.Data),
cert_data.Length);
base::StringPiece spki_bytes;
if (!asn1::ExtractSPKIFromDERCert(der_bytes, &spki_bytes))
continue;
HashValue sha256(HASH_VALUE_SHA256);
CC_SHA256(spki_bytes.data(), spki_bytes.size(), sha256.data());
hashes->push_back(sha256);
}
}
enum CRLSetResult {
kCRLSetOk,
kCRLSetRevoked,
kCRLSetUnknown,
};
// CheckRevocationWithCRLSet attempts to check each element of |cert_list|
// 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 CheckRevocationWithCRLSet(CFArrayRef chain, CRLSet* crl_set) {
if (CFArrayGetCount(chain) == 0)
return kCRLSetOk;
// error is set to true if any errors are found. It causes such chains to be
// considered as not covered.
bool error = false;
// last_covered is set to the coverage state of the previous certificate. The
// certificates are iterated over backwards thus, after the iteration,
// |last_covered| contains the coverage state of the leaf certificate.
bool last_covered = false;
// We iterate from the root certificate down to the leaf, keeping track of
// the issuer's SPKI at each step.
std::string issuer_spki_hash;
for (CFIndex i = CFArrayGetCount(chain) - 1; i >= 0; i--) {
SecCertificateRef cert = reinterpret_cast<SecCertificateRef>(
const_cast<void*>(CFArrayGetValueAtIndex(chain, i)));
CSSM_DATA cert_data;
OSStatus err = SecCertificateGetData(cert, &cert_data);
if (err != noErr) {
NOTREACHED();
error = true;
continue;
}
base::StringPiece der_bytes(reinterpret_cast<const char*>(cert_data.Data),
cert_data.Length);
base::StringPiece spki, subject;
if (!asn1::ExtractSPKIFromDERCert(der_bytes, &spki) ||
!asn1::ExtractSubjectFromDERCert(der_bytes, &subject)) {
NOTREACHED();
error = true;
continue;
}
const std::string spki_hash = crypto::SHA256HashString(spki);
x509_util::CSSMCachedCertificate cached_cert;
if (cached_cert.Init(cert) != CSSM_OK) {
NOTREACHED();
error = true;
continue;
}
x509_util::CSSMFieldValue serial_number;
err = cached_cert.GetField(&CSSMOID_X509V1SerialNumber, &serial_number);
if (err || !serial_number.field()) {
NOTREACHED();
error = true;
continue;
}
base::StringPiece serial(
reinterpret_cast<const char*>(serial_number.field()->Data),
serial_number.field()->Length);
CRLSet::Result result = crl_set->CheckSPKI(spki_hash);
if (result != CRLSet::REVOKED)
result = crl_set->CheckSubject(subject, spki_hash);
if (result != CRLSet::REVOKED && !issuer_spki_hash.empty())
result = crl_set->CheckSerial(serial, issuer_spki_hash);
issuer_spki_hash = spki_hash;
switch (result) {
case CRLSet::REVOKED:
return kCRLSetRevoked;
case CRLSet::UNKNOWN:
last_covered = false;
continue;
case CRLSet::GOOD:
last_covered = true;
continue;
default:
NOTREACHED();
error = true;
continue;
}
}
if (error || !last_covered || crl_set->IsExpired())
return kCRLSetUnknown;
return kCRLSetOk;
}
// Builds and evaluates a SecTrustRef for the certificate chain contained
// in |cert_array|, using the verification policies in |trust_policies|. On
// success, returns OK, and updates |trust_ref|, |trust_result|,
// |verified_chain|, and |chain_info| with the verification results. On
// failure, no output parameters are modified.
//
// Note: An OK return does not mean that |cert_array| is trusted, merely that
// verification was performed successfully.
//
// This function should only be called while the Mac Security Services lock is
// held.
int BuildAndEvaluateSecTrustRef(CFArrayRef cert_array,
CFArrayRef trust_policies,
int flags,
CFArrayRef keychain_search_list,
ScopedCFTypeRef<SecTrustRef>* trust_ref,
SecTrustResultType* trust_result,
ScopedCFTypeRef<CFArrayRef>* verified_chain,
CSSM_TP_APPLE_EVIDENCE_INFO** chain_info) {
SecTrustRef tmp_trust = NULL;
OSStatus status = SecTrustCreateWithCertificates(cert_array, trust_policies,
&tmp_trust);
if (status)
return NetErrorFromOSStatus(status);
ScopedCFTypeRef<SecTrustRef> scoped_tmp_trust(tmp_trust);
if (TestRootCerts::HasInstance()) {
status = TestRootCerts::GetInstance()->FixupSecTrustRef(tmp_trust);
if (status)
return NetErrorFromOSStatus(status);
}
if (keychain_search_list) {
status = SecTrustSetKeychains(tmp_trust, keychain_search_list);
if (status)
return NetErrorFromOSStatus(status);
}
CSSM_APPLE_TP_ACTION_DATA tp_action_data;
memset(&tp_action_data, 0, sizeof(tp_action_data));
tp_action_data.Version = CSSM_APPLE_TP_ACTION_VERSION;
// Allow CSSM to download any missing intermediate certificates if an
// authorityInfoAccess extension or issuerAltName extension is present.
tp_action_data.ActionFlags = CSSM_TP_ACTION_FETCH_CERT_FROM_NET |
CSSM_TP_ACTION_TRUST_SETTINGS;
// Note: For EV certificates, the Apple TP will handle setting these flags
// as part of EV evaluation.
if (flags & CertVerifier::VERIFY_REV_CHECKING_ENABLED) {
// Require a positive result from an OCSP responder or a CRL (or both)
// for every certificate in the chain. The Apple TP automatically
// excludes the self-signed root from this requirement. If a certificate
// is missing both a crlDistributionPoints extension and an
// authorityInfoAccess extension with an OCSP responder URL, then we
// will get a kSecTrustResultRecoverableTrustFailure back from
// SecTrustEvaluate(), with a
// CSSMERR_APPLETP_INCOMPLETE_REVOCATION_CHECK error code. In that case,
// we'll set our own result to include
// CERT_STATUS_NO_REVOCATION_MECHANISM. If one or both extensions are
// present, and a check fails (server unavailable, OCSP retry later,
// signature mismatch), then we'll set our own result to include
// CERT_STATUS_UNABLE_TO_CHECK_REVOCATION.
tp_action_data.ActionFlags |= CSSM_TP_ACTION_REQUIRE_REV_PER_CERT;
// Note, even if revocation checking is disabled, SecTrustEvaluate() will
// modify the OCSP options so as to attempt OCSP checking if it believes a
// certificate may chain to an EV root. However, because network fetches
// are disabled in CreateTrustPolicies() when revocation checking is
// disabled, these will only go against the local cache.
}
CFDataRef action_data_ref =
CFDataCreateWithBytesNoCopy(kCFAllocatorDefault,
reinterpret_cast<UInt8*>(&tp_action_data),
sizeof(tp_action_data), kCFAllocatorNull);
if (!action_data_ref)
return ERR_OUT_OF_MEMORY;
ScopedCFTypeRef<CFDataRef> scoped_action_data_ref(action_data_ref);
status = SecTrustSetParameters(tmp_trust, CSSM_TP_ACTION_DEFAULT,
action_data_ref);
if (status)
return NetErrorFromOSStatus(status);
// Verify the certificate. A non-zero result from SecTrustGetResult()
// indicates that some fatal error occurred and the chain couldn't be
// processed, not that the chain contains no errors. We need to examine the
// output of SecTrustGetResult() to determine that.
SecTrustResultType tmp_trust_result;
status = SecTrustEvaluate(tmp_trust, &tmp_trust_result);
if (status)
return NetErrorFromOSStatus(status);
CFArrayRef tmp_verified_chain = NULL;
CSSM_TP_APPLE_EVIDENCE_INFO* tmp_chain_info;
status = SecTrustGetResult(tmp_trust, &tmp_trust_result, &tmp_verified_chain,
&tmp_chain_info);
if (status)
return NetErrorFromOSStatus(status);
trust_ref->swap(scoped_tmp_trust);
*trust_result = tmp_trust_result;
verified_chain->reset(tmp_verified_chain);
*chain_info = tmp_chain_info;
return OK;
}
// IsIssuedByKnownRoot returns true if the given chain is rooted at a root CA
// that we recognise as a standard root.
bool IsIssuedByKnownRoot(CFArrayRef chain) {
CFIndex n = CFArrayGetCount(chain);
if (n < 1)
return false;
SecCertificateRef root_ref = reinterpret_cast<SecCertificateRef>(
const_cast<void*>(CFArrayGetValueAtIndex(chain, n - 1)));
return IsKnownRoot(root_ref);
}
// Runs path building & verification loop for |cert|, given |flags|. This is
// split into a separate function so verification can be repeated with different
// flags. This function does not handle EV.
int VerifyWithGivenFlags(X509Certificate* cert,
const std::string& hostname,
const int flags,
CRLSet* crl_set,
CertVerifyResult* verify_result,
CRLSetResult* completed_chain_crl_result) {
ScopedCFTypeRef<CFArrayRef> trust_policies;
OSStatus status = CreateTrustPolicies(flags, &trust_policies);
if (status)
return NetErrorFromOSStatus(status);
*completed_chain_crl_result = kCRLSetUnknown;
// Serialize all calls that may use the Keychain, to work around various
// issues in OS X 10.6+ with multi-threaded access to Security.framework.
base::AutoLock lock(crypto::GetMacSecurityServicesLock());
ScopedCFTypeRef<SecTrustRef> trust_ref;
SecTrustResultType trust_result = kSecTrustResultDeny;
ScopedCFTypeRef<CFArrayRef> completed_chain;
CSSM_TP_APPLE_EVIDENCE_INFO* chain_info = NULL;
bool candidate_untrusted = true;
bool candidate_weak = false;
// OS X lacks proper path discovery; it will take the input certs and never
// backtrack the graph attempting to discover valid paths.
// This can create issues in some situations:
// - When OS X changes the trust store, there may be a chain
// A -> B -> C -> D
// where OS X trusts D (on some versions) and trusts C (on some versions).
// If a server supplies a chain A, B, C (cross-signed by D), then this chain
// will successfully validate on systems that trust D, but fail for systems
// that trust C. If the server supplies a chain of A -> B, then it forces
// all clients to fetch C (via AIA) if they trust D, and not all clients
// (notably, Firefox and Android) will do this, thus breaking them.
// An example of this is the Verizon Business Services root - GTE CyberTrust
// and Baltimore CyberTrust roots represent old and new roots that cause
// issues depending on which version of OS X being used.
//
// - A server may be (misconfigured) to send an expired intermediate
// certificate. On platforms with path discovery, the graph traversal
// will back up to immediately before this intermediate, and then
// attempt an AIA fetch or retrieval from local store. However, OS X
// does not do this, and thus prevents access. While this is ostensibly
// a server misconfiguration issue, the fact that it works on other
// platforms is a jarring inconsistency for users.
//
// - When OS X trusts both C and D (simultaneously), it's possible that the
// version of C signed by D is signed using a weak algorithm (e.g. SHA-1),
// while the version of C in the trust store's signature doesn't matter.
// Since a 'strong' chain exists, it would be desirable to prefer this
// chain.
//
// - A variant of the above example, it may be that the version of B sent by
// the server is signed using a weak algorithm, but the version of B
// present in the AIA of A is signed using a strong algorithm. Since a
// 'strong' chain exists, it would be desirable to prefer this chain.
//
// - A user keychain may contain a less desirable intermediate or root.
// OS X gives the user keychains higher priority than the system keychain,
// so it may build a weak chain.
//
// Because of this, the code below first attempts to validate the peer's
// identity using the supplied chain. If it is not trusted (e.g. the OS only
// trusts C, but the version of C signed by D was sent, and D is not trusted),
// or if it contains a weak chain, it will begin lopping off certificates
// from the end of the chain and attempting to verify. If a stronger, trusted
// chain is found, it is used, otherwise, the algorithm continues until only
// the peer's certificate remains.
//
// If the loop does not find a trusted chain, the loop will be repeated with
// the keychain search order altered to give priority to the System Roots
// keychain.
//
// This does cause a performance hit for these users, but only in cases where
// OS X is building weaker chains than desired, or when it would otherwise
// fail the connection.
for (bool try_reordered_keychain : {false, true}) {
ScopedCFTypeRef<CFArrayRef> scoped_alternate_keychain_search_list;
if (TestKeychainSearchList::HasInstance()) {
// Unit tests need to be able to hermetically simulate situations where a
// user has an undesirable certificate in a per-user keychain.
// Adding/Removing a Keychain using SecKeychainCreate/SecKeychainDelete
// has global side effects, which would break other tests and processes
// running on the same machine, so instead tests may load pre-created
// keychains using SecKeychainOpen and then inject them through
// TestKeychainSearchList.
CFArrayRef keychain_search_list;
status = TestKeychainSearchList::GetInstance()->CopySearchList(
&keychain_search_list);
if (status)
return NetErrorFromOSStatus(status);
scoped_alternate_keychain_search_list.reset(keychain_search_list);
}
if (try_reordered_keychain) {
// If a TestKeychainSearchList is present, it will have already set
// |scoped_alternate_keychain_search_list|, which will be used as the
// basis for reordering the keychain. Otherwise, get the current keychain
// search list and use that.
if (!scoped_alternate_keychain_search_list) {
CFArrayRef keychain_search_list;
status = SecKeychainCopySearchList(&keychain_search_list);
if (status)
return NetErrorFromOSStatus(status);
scoped_alternate_keychain_search_list.reset(keychain_search_list);
}
CFMutableArrayRef mutable_keychain_search_list = CFArrayCreateMutableCopy(
kCFAllocatorDefault,
CFArrayGetCount(scoped_alternate_keychain_search_list.get()) + 1,
scoped_alternate_keychain_search_list.get());
if (!mutable_keychain_search_list)
return ERR_OUT_OF_MEMORY;
scoped_alternate_keychain_search_list.reset(mutable_keychain_search_list);
SecKeychainRef keychain;
// Get a reference to the System Roots keychain. The System Roots
// keychain is not normally present in the keychain search list, but is
// implicitly checked after the keychains in the search list. By
// including it directly, force it to be checked first. This is a gross
// hack, but the path is known to be valid on OS X 10.9-10.11.
status = SecKeychainOpen(
"/System/Library/Keychains/SystemRootCertificates.keychain",
&keychain);
if (status)
return NetErrorFromOSStatus(status);
ScopedCFTypeRef<SecKeychainRef> scoped_keychain(keychain);
CFArrayInsertValueAtIndex(mutable_keychain_search_list, 0, keychain);
}
ScopedCFTypeRef<CFMutableArrayRef> cert_array(
x509_util::CreateSecCertificateArrayForX509Certificate(
cert, x509_util::InvalidIntermediateBehavior::kIgnore));
if (!cert_array) {
verify_result->cert_status |= CERT_STATUS_INVALID;
return ERR_CERT_INVALID;
}
// Beginning with the certificate chain as supplied by the server, attempt
// to verify the chain. If a failure is encountered, trim a certificate
// from the end (so long as one remains) and retry, in the hope of forcing
// OS X to find a better path.
while (CFArrayGetCount(cert_array) > 0) {
ScopedCFTypeRef<SecTrustRef> temp_ref;
SecTrustResultType temp_trust_result = kSecTrustResultDeny;
ScopedCFTypeRef<CFArrayRef> temp_chain;
CSSM_TP_APPLE_EVIDENCE_INFO* temp_chain_info = NULL;
int rv = BuildAndEvaluateSecTrustRef(
cert_array, trust_policies, flags,
scoped_alternate_keychain_search_list.get(), &temp_ref,
&temp_trust_result, &temp_chain, &temp_chain_info);
if (rv != OK)
return rv;
// Check to see if the path |temp_chain| has been revoked. This is less
// than ideal to perform after path building, rather than during, because
// there may be multiple paths to trust anchors, and only some of them
// are revoked. Ideally, CRLSets would be part of path building, which
// they are when using NSS (Linux) or CryptoAPI (Windows).
//
// The CRLSet checking is performed inside the loop in the hope that if a
// path is revoked, it's an older path, and the only reason it was built
// is because the server forced it (by supplying an older or less
// desirable intermediate) or because the user had installed a
// certificate in their Keychain forcing this path. However, this means
// its still possible for a CRLSet block of an intermediate to prevent
// access, even when there is a 'good' chain. To fully remedy this, a
// solution might be to have CRLSets contain enough knowledge about what
// the 'desired' path might be, but for the time being, the
// implementation is kept as 'simple' as it can be.
CRLSetResult crl_result = kCRLSetUnknown;
if (crl_set)
crl_result = CheckRevocationWithCRLSet(temp_chain, crl_set);
bool untrusted = (temp_trust_result != kSecTrustResultUnspecified &&
temp_trust_result != kSecTrustResultProceed) ||
crl_result == kCRLSetRevoked;
bool weak_chain = false;
if (CFArrayGetCount(temp_chain) == 0) {
// If the chain is empty, it cannot be trusted or have recoverable
// errors.
DCHECK(untrusted);
DCHECK_NE(kSecTrustResultRecoverableTrustFailure, temp_trust_result);
} else {
weak_chain =
IsWeakChainBasedOnHashingAlgorithms(temp_chain, temp_chain_info);
}
// Set the result to the current chain if:
// - This is the first verification attempt. This ensures that if
// everything is awful (e.g. it may just be an untrusted cert), that
// what is reported is exactly what was sent by the server
// - If the current chain is trusted, and the old chain was not trusted,
// then prefer this chain. This ensures that if there is at least a
// valid path to a trust anchor, it's preferred over reporting an error.
// - If the current chain is trusted, and the old chain is trusted, but
// the old chain contained weak algorithms while the current chain only
// contains strong algorithms, then prefer the current chain over the
// old chain.
//
// Note: If the leaf certificate itself is weak, then the only
// consideration is whether or not there is a trusted chain. That's
// because no amount of path discovery will fix a weak leaf.
if (!trust_ref || (!untrusted && (candidate_untrusted ||
(candidate_weak && !weak_chain)))) {
trust_ref = temp_ref;
trust_result = temp_trust_result;
completed_chain = temp_chain;
*completed_chain_crl_result = crl_result;
chain_info = temp_chain_info;
candidate_untrusted = untrusted;
candidate_weak = weak_chain;
}
// Short-circuit when a current, trusted chain is found.
if (!untrusted && !weak_chain)
break;
CFArrayRemoveValueAtIndex(cert_array, CFArrayGetCount(cert_array) - 1);
}
// Short-circuit when a current, trusted chain is found.
if (!candidate_untrusted && !candidate_weak)
break;
}
if (flags & CertVerifier::VERIFY_REV_CHECKING_ENABLED)
verify_result->cert_status |= CERT_STATUS_REV_CHECKING_ENABLED;
if (*completed_chain_crl_result == kCRLSetRevoked)
verify_result->cert_status |= CERT_STATUS_REVOKED;
if (CFArrayGetCount(completed_chain) > 0) {
CopyCertChainToVerifyResult(completed_chain, verify_result);
}
// As of Security Update 2012-002/OS X 10.7.4, when an RSA key < 1024 bits
// is encountered, CSSM returns CSSMERR_TP_VERIFY_ACTION_FAILED and adds
// CSSMERR_CSP_UNSUPPORTED_KEY_SIZE as a certificate status. Avoid mapping
// the CSSMERR_TP_VERIFY_ACTION_FAILED to CERT_STATUS_INVALID if the only
// error was due to an unsupported key size.
bool policy_failed = false;
bool policy_fail_already_mapped = false;
bool weak_key_or_signature_algorithm = false;
// Evaluate the results
OSStatus cssm_result;
switch (trust_result) {
case kSecTrustResultUnspecified:
case kSecTrustResultProceed:
// Certificate chain is valid and trusted ("unspecified" indicates that
// the user has not explicitly set a trust setting)
break;
// According to SecTrust.h, kSecTrustResultConfirm isn't returned on 10.5+,
// and it is marked deprecated in the 10.9 SDK.
case kSecTrustResultDeny:
// Certificate chain is explicitly untrusted.
verify_result->cert_status |= CERT_STATUS_AUTHORITY_INVALID;
break;
case kSecTrustResultRecoverableTrustFailure:
// Certificate chain has a failure that can be overridden by the user.
status = SecTrustGetCssmResultCode(trust_ref, &cssm_result);
if (status)
return NetErrorFromOSStatus(status);
if (cssm_result == CSSMERR_TP_VERIFY_ACTION_FAILED) {
policy_failed = true;
} else {
verify_result->cert_status |= CertStatusFromOSStatus(cssm_result);
}
// Walk the chain of error codes in the CSSM_TP_APPLE_EVIDENCE_INFO
// structure which can catch multiple errors from each certificate.
for (CFIndex index = 0, chain_count = CFArrayGetCount(completed_chain);
index < chain_count; ++index) {
if (chain_info[index].StatusBits & CSSM_CERT_STATUS_EXPIRED ||
chain_info[index].StatusBits & CSSM_CERT_STATUS_NOT_VALID_YET)
verify_result->cert_status |= CERT_STATUS_DATE_INVALID;
if (!IsCertStatusError(verify_result->cert_status) &&
chain_info[index].NumStatusCodes == 0) {
LOG(WARNING) << "chain_info[" << index << "].NumStatusCodes is 0"
", chain_info[" << index << "].StatusBits is "
<< chain_info[index].StatusBits;
}
for (uint32_t status_code_index = 0;
status_code_index < chain_info[index].NumStatusCodes;
++status_code_index) {
// As of OS X 10.9, attempting to verify a certificate chain that
// contains a weak signature algorithm (MD2, MD5) in an intermediate
// or leaf cert will be treated as a (recoverable) policy validation
// failure, with the status code CSSMERR_TP_INVALID_CERTIFICATE
// added to the Status Codes. Don't treat this code as an invalid
// certificate; instead, map it to a weak key. Any truly invalid
// certificates will have the major error (cssm_result) set to
// CSSMERR_TP_INVALID_CERTIFICATE, rather than
// CSSMERR_TP_VERIFY_ACTION_FAILED.
CertStatus mapped_status = 0;
if (policy_failed &&
chain_info[index].StatusCodes[status_code_index] ==
CSSMERR_TP_INVALID_CERTIFICATE) {
mapped_status = CERT_STATUS_WEAK_SIGNATURE_ALGORITHM;
weak_key_or_signature_algorithm = true;
policy_fail_already_mapped = true;
} else if (policy_failed &&
(flags & CertVerifier::VERIFY_REV_CHECKING_ENABLED) &&
chain_info[index].StatusCodes[status_code_index] ==
CSSMERR_TP_VERIFY_ACTION_FAILED &&
base::mac::IsOS10_12()) {
// On early versions of 10.12, using
// kSecRevocationRequirePositiveResponse flag causes a
// CSSMERR_TP_VERIFY_ACTION_FAILED status if revocation couldn't be
// checked. (Note: even if the cert had no crlDistributionPoints or
// OCSP AIA.) This isn't needed on later 10.12 versions, but it
// should be mostly harmless.
mapped_status = CERT_STATUS_UNABLE_TO_CHECK_REVOCATION;
policy_fail_already_mapped = true;
} else {
mapped_status = CertStatusFromOSStatus(
chain_info[index].StatusCodes[status_code_index]);
if (mapped_status == CERT_STATUS_WEAK_KEY) {
weak_key_or_signature_algorithm = true;
policy_fail_already_mapped = true;
}
}
verify_result->cert_status |= mapped_status;
}
}
if (policy_failed && !policy_fail_already_mapped) {
// If CSSMERR_TP_VERIFY_ACTION_FAILED wasn't returned due to a weak
// key or problem checking revocation, map it back to an appropriate
// error code.
verify_result->cert_status |= CertStatusFromOSStatus(cssm_result);
}
if (!IsCertStatusError(verify_result->cert_status)) {
LOG(ERROR) << "cssm_result=" << cssm_result;
verify_result->cert_status |= CERT_STATUS_INVALID;
NOTREACHED();
}
break;
default:
status = SecTrustGetCssmResultCode(trust_ref, &cssm_result);
if (status)
return NetErrorFromOSStatus(status);
verify_result->cert_status |= CertStatusFromOSStatus(cssm_result);
if (!IsCertStatusError(verify_result->cert_status)) {
LOG(WARNING) << "trust_result=" << trust_result;
verify_result->cert_status |= CERT_STATUS_INVALID;
}
break;
}
// Hostname validation is handled by CertVerifyProc, so mask off any errors
// that SecTrustEvaluate may have set, as its results are not used.
verify_result->cert_status &= ~CERT_STATUS_COMMON_NAME_INVALID;
// TODO(wtc): Suppress CERT_STATUS_NO_REVOCATION_MECHANISM for now to be
// compatible with Windows, which in turn implements this behavior to be
// compatible with WinHTTP, which doesn't report this error (bug 3004).
verify_result->cert_status &= ~CERT_STATUS_NO_REVOCATION_MECHANISM;
AppendPublicKeyHashes(completed_chain, &verify_result->public_key_hashes);
verify_result->is_issued_by_known_root = IsIssuedByKnownRoot(completed_chain);
if (IsCertStatusError(verify_result->cert_status))
return MapCertStatusToNetError(verify_result->cert_status);
return OK;
}
} // namespace
CertVerifyProcMac::CertVerifyProcMac() {}
CertVerifyProcMac::~CertVerifyProcMac() {}
bool CertVerifyProcMac::SupportsAdditionalTrustAnchors() const {
return false;
}
bool CertVerifyProcMac::SupportsOCSPStapling() const {
// TODO(rsleevi): Plumb an OCSP response into the Mac system library.
// https://crbug.com/430714
return false;
}
int CertVerifyProcMac::VerifyInternal(
X509Certificate* cert,
const std::string& hostname,
const std::string& ocsp_response,
int flags,
CRLSet* crl_set,
const CertificateList& additional_trust_anchors,
CertVerifyResult* verify_result) {
// Save the input state of |*verify_result|, which may be needed to re-do
// verification with different flags.
const CertVerifyResult input_verify_result(*verify_result);
// If EV verification is enabled, check for EV policy in leaf cert.
std::string candidate_ev_policy_oid;
if (flags & CertVerifier::VERIFY_EV_CERT)
GetCandidateEVPolicy(cert, &candidate_ev_policy_oid);
CRLSetResult completed_chain_crl_result;
int rv = VerifyWithGivenFlags(cert, hostname, flags, crl_set, verify_result,
&completed_chain_crl_result);
if (rv != OK)
return rv;
if (!candidate_ev_policy_oid.empty() &&
CheckCertChainEV(verify_result->verified_cert.get(),
candidate_ev_policy_oid)) {
// EV policies check out and the verification succeeded. See if revocation
// checking still needs to be done before it can be marked as EV.
if (completed_chain_crl_result == kCRLSetUnknown &&
(flags & CertVerifier::VERIFY_REV_CHECKING_ENABLED_EV_ONLY) &&
!(flags & CertVerifier::VERIFY_REV_CHECKING_ENABLED)) {
// If this is an EV cert and it wasn't covered by CRLSets and revocation
// checking wasn't already on, try again with revocation forced on.
//
// Restore the input state of |*verify_result|, so that the
// re-verification starts with a clean slate.
*verify_result = input_verify_result;
int tmp_rv = VerifyWithGivenFlags(
verify_result->verified_cert.get(), hostname,
flags | CertVerifier::VERIFY_REV_CHECKING_ENABLED, crl_set,
verify_result, &completed_chain_crl_result);
// If re-verification failed, return those results without setting EV
// status.
if (tmp_rv != OK)
return tmp_rv;
// Otherwise, fall through and add the EV status flag.
}
// EV cert and it was covered by CRLSets or revocation checking passed.
verify_result->cert_status |= CERT_STATUS_IS_EV;
}
return OK;
}
} // namespace net
#pragma clang diagnostic pop // "-Wdeprecated-declarations"