//
// Executable code.
// Read from disk, evaluate properly, cache as indicated. The whole thing, so far.
//
void PolicyEngine::evaluateCode(CFURLRef path, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context, CFMutableDictionaryRef result,
bool handleUnsignedCode /* = true */)
{
FileQuarantine qtn(cfString(path).c_str());
if (qtn.flag(QTN_FLAG_HARD))
MacOSError::throwMe(errSecCSFileHardQuarantined);
CFRef<SecStaticCodeRef> code;
MacOSError::check(SecStaticCodeCreateWithPath(path, kSecCSDefaultFlags, &code.aref()));
OSStatus rc = noErr; // last validation error
const SecCSFlags validationFlags = kSecCSEnforceRevocationChecks;
WhitelistPrescreen whitelistScreen(code); // pre-screening filter for whitelist pre-screening (only)
SQLite::Statement query(*this,
"SELECT allow, requirement, id, label, expires, flags, disabled, filter_unsigned, remarks FROM scan_authority"
" WHERE type = :type"
" ORDER BY priority DESC;");
query.bind(":type").integer(type);
SQLite3::int64 latentID = 0; // first (highest priority) disabled matching ID
std::string latentLabel; // ... and associated label, if any
while (query.nextRow()) {
bool allow = int(query[0]);
const char *reqString = query[1];
SQLite3::int64 id = query[2];
const char *label = query[3];
double expires = query[4];
sqlite3_int64 ruleFlags = query[5];
SQLite3::int64 disabled = query[6];
const char *filter = query[7];
const char *remarks = query[8];
CFRef<SecRequirementRef> requirement;
MacOSError::check(SecRequirementCreateWithString(CFTempString(reqString), kSecCSDefaultFlags, &requirement.aref()));
rc = SecStaticCodeCheckValidity(code, validationFlags, requirement);
// ad-hoc sign unsigned code, skip of Gatekeeper is off or the rule is disabled; but always do it for whitelist recording
if (rc == errSecCSUnsigned && handleUnsignedCode && (!(disabled || overrideAssessment()) || SYSPOLICY_RECORDER_MODE_ENABLED())) {
if (!SYSPOLICY_RECORDER_MODE_ENABLED()) {
// apply whitelist pre-screening to speed things up for non-matches
if (ruleFlags & kAuthorityFlagDefault) // can't ever match standard rules with unsigned code
continue;
if (whitelistScreen.reject(filter, remarks)) // apply whitelist pre-filter
continue;
}
try {
// ad-hoc sign the code and attach the signature
CFRef<CFDataRef> signature = CFDataCreateMutable(NULL, 0);
CFTemp<CFDictionaryRef> arguments("{%O=%O, %O=#N}", kSecCodeSignerDetached, signature.get(), kSecCodeSignerIdentity);
CFRef<SecCodeSignerRef> signer;
MacOSError::check(SecCodeSignerCreate(arguments, kSecCSDefaultFlags, &signer.aref()));
MacOSError::check(SecCodeSignerAddSignature(signer, code, kSecCSDefaultFlags));
MacOSError::check(SecCodeSetDetachedSignature(code, signature, kSecCSDefaultFlags));
// if we're in GKE recording mode, save that signature and report its location
if (SYSPOLICY_RECORDER_MODE_ENABLED()) {
int status = recorder_code_unable; // ephemeral signature (not recorded)
if (geteuid() == 0) {
CFRef<CFUUIDRef> uuid = CFUUIDCreate(NULL);
std::string sigfile = RECORDER_DIR + cfStringRelease(CFUUIDCreateString(NULL, uuid)) + ".tsig";
try {
UnixPlusPlus::AutoFileDesc fd(sigfile, O_WRONLY | O_CREAT);
fd.write(CFDataGetBytePtr(signature), CFDataGetLength(signature));
status = recorder_code_adhoc; // recorded signature
SYSPOLICY_RECORDER_MODE_ADHOC_PATH(cfString(path).c_str(), type, sigfile.c_str());
} catch (...) { }
}
// now report the D probe itself
CFRef<CFDictionaryRef> info;
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSDefaultFlags, &info.aref()));
CFDataRef cdhash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
SYSPOLICY_RECORDER_MODE(cfString(path).c_str(), type, "",
cdhash ? CFDataGetBytePtr(cdhash) : NULL, status);
}
// rerun the validation to update state
rc = SecStaticCodeCheckValidity(code, validationFlags | kSecCSBasicValidateOnly, requirement);
} catch (...) { }
}
switch (rc) {
case noErr: // well signed and satisfies requirement...
break; // ... continue below
case errSecCSSignatureFailed:
if (!codeInvalidityExceptions(code, result)) {
if (SYSPOLICY_ASSESS_OUTCOME_BROKEN_ENABLED())
SYSPOLICY_ASSESS_OUTCOME_BROKEN(cfString(path).c_str(), type, false);
MacOSError::throwMe(rc);
}
if (SYSPOLICY_ASSESS_OUTCOME_BROKEN_ENABLED())
SYSPOLICY_ASSESS_OUTCOME_BROKEN(cfString(path).c_str(), type, true);
// treat as unsigned to fix problems in the field
case errSecCSUnsigned:
if (handleUnsignedCode) {
cfadd(result, "{%O=#F}", kSecAssessmentAssessmentVerdict);
addAuthority(result, "no usable signature");
}
return;
case errSecCSReqFailed: // requirement missed, but otherwise okay
continue;
default: // broken in some way; all tests will fail like this so bail out
MacOSError::throwMe(rc);
}
if (disabled) {
if (latentID == 0) {
latentID = id;
if (label)
latentLabel = label;
}
continue; // the loop
}
CFRef<CFDictionaryRef> info; // as needed
if (flags & kSecAssessmentFlagRequestOrigin) {
if (!info)
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
if (CFArrayRef chain = CFArrayRef(CFDictionaryGetValue(info, kSecCodeInfoCertificates)))
setOrigin(chain, result);
}
if (!(ruleFlags & kAuthorityFlagInhibitCache) && !(flags & kSecAssessmentFlagNoCache)) { // cache inhibit
if (!info)
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
if (SecTrustRef trust = SecTrustRef(CFDictionaryGetValue(info, kSecCodeInfoTrust))) {
CFRef<CFDictionaryRef> xinfo;
MacOSError::check(SecTrustCopyExtendedResult(trust, &xinfo.aref()));
if (CFDateRef limit = CFDateRef(CFDictionaryGetValue(xinfo, kSecTrustExpirationDate))) {
this->recordOutcome(code, allow, type, min(expires, dateToJulian(limit)), id);
}
}
}
if (allow) {
if (SYSPOLICY_ASSESS_OUTCOME_ACCEPT_ENABLED()) {
if (!info)
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
CFDataRef cdhash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
SYSPOLICY_ASSESS_OUTCOME_ACCEPT(cfString(path).c_str(), type, label, cdhash ? CFDataGetBytePtr(cdhash) : NULL);
}
} else {
if (SYSPOLICY_ASSESS_OUTCOME_DENY_ENABLED() || SYSPOLICY_RECORDER_MODE_ENABLED()) {
if (!info)
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
CFDataRef cdhash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
std::string cpath = cfString(path);
const void *hashp = cdhash ? CFDataGetBytePtr(cdhash) : NULL;
SYSPOLICY_ASSESS_OUTCOME_DENY(cpath.c_str(), type, label, hashp);
SYSPOLICY_RECORDER_MODE(cpath.c_str(), type, label, hashp, recorder_code_untrusted);
}
}
cfadd(result, "{%O=%B}", kSecAssessmentAssessmentVerdict, allow);
addAuthority(result, label, id);
return;
}
if (rc == errSecCSUnsigned) { // skipped all applicable rules due to pre-screening
cfadd(result, "{%O=#F}", kSecAssessmentAssessmentVerdict);
addAuthority(result, "no usable signature");
return;
}
// no applicable authority (but signed, perhaps temporarily). Deny by default
CFRef<CFDictionaryRef> info;
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
if (flags & kSecAssessmentFlagRequestOrigin) {
if (CFArrayRef chain = CFArrayRef(CFDictionaryGetValue(info, kSecCodeInfoCertificates)))
setOrigin(chain, result);
}
if (SYSPOLICY_ASSESS_OUTCOME_DEFAULT_ENABLED() || SYSPOLICY_RECORDER_MODE_ENABLED()) {
CFDataRef cdhash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
const void *hashp = cdhash ? CFDataGetBytePtr(cdhash) : NULL;
std::string cpath = cfString(path);
SYSPOLICY_ASSESS_OUTCOME_DEFAULT(cpath.c_str(), type, latentLabel.c_str(), hashp);
SYSPOLICY_RECORDER_MODE(cpath.c_str(), type, latentLabel.c_str(), hashp, 0);
}
if (!(flags & kSecAssessmentFlagNoCache))
this->recordOutcome(code, false, type, this->julianNow() + NEGATIVE_HOLD, latentID);
cfadd(result, "{%O=%B}", kSecAssessmentAssessmentVerdict, false);
addAuthority(result, latentLabel.c_str(), latentID);
}
//
// Installer archive.
// Hybrid policy: If we detect an installer signature, use and validate that.
// If we don't, check for a code signature instead.
//
void PolicyEngine::evaluateInstall(CFURLRef path, SecAssessmentFlags flags, CFDictionaryRef context, CFMutableDictionaryRef result)
{
const AuthorityType type = kAuthorityInstall;
Xar xar(cfString(path).c_str());
if (!xar) {
// follow the code signing path
evaluateCode(path, type, flags, context, result);
return;
}
SQLite3::int64 latentID = 0; // first (highest priority) disabled matching ID
std::string latentLabel; // ... and associated label, if any
if (!xar.isSigned()) {
// unsigned xar
if (SYSPOLICY_ASSESS_OUTCOME_UNSIGNED_ENABLED())
SYSPOLICY_ASSESS_OUTCOME_UNSIGNED(cfString(path).c_str(), type);
cfadd(result, "{%O=%B}", kSecAssessmentAssessmentVerdict, false);
addAuthority(result, "no usable signature");
return;
}
if (CFRef<CFArrayRef> certs = xar.copyCertChain()) {
CFRef<CFTypeRef> policy = installerPolicy();
CFRef<SecTrustRef> trust;
MacOSError::check(SecTrustCreateWithCertificates(certs, policy, &trust.aref()));
// MacOSError::check(SecTrustSetAnchorCertificates(trust, cfEmptyArray())); // no anchors
MacOSError::check(SecTrustSetOptions(trust, kSecTrustOptionAllowExpired | kSecTrustOptionImplicitAnchors));
SecTrustResultType trustResult;
MacOSError::check(SecTrustEvaluate(trust, &trustResult));
CFRef<CFArrayRef> chain;
CSSM_TP_APPLE_EVIDENCE_INFO *info;
MacOSError::check(SecTrustGetResult(trust, &trustResult, &chain.aref(), &info));
if (flags & kSecAssessmentFlagRequestOrigin)
setOrigin(chain, result);
switch (trustResult) {
case kSecTrustResultProceed:
case kSecTrustResultUnspecified:
break;
default:
{
OSStatus rc;
MacOSError::check(SecTrustGetCssmResultCode(trust, &rc));
MacOSError::throwMe(rc);
}
}
SQLite::Statement query(*this,
"SELECT allow, requirement, id, label, flags, disabled FROM scan_authority"
" WHERE type = :type"
" ORDER BY priority DESC;");
query.bind(":type").integer(type);
while (query.nextRow()) {
bool allow = int(query[0]);
const char *reqString = query[1];
SQLite3::int64 id = query[2];
const char *label = query[3];
//sqlite_uint64 ruleFlags = query[4];
SQLite3::int64 disabled = query[5];
CFRef<SecRequirementRef> requirement;
MacOSError::check(SecRequirementCreateWithString(CFTempString(reqString), kSecCSDefaultFlags, &requirement.aref()));
switch (OSStatus rc = SecRequirementEvaluate(requirement, chain, NULL, kSecCSDefaultFlags)) {
case noErr: // success
break;
case errSecCSReqFailed: // requirement missed, but otherwise okay
continue;
default: // broken in some way; all tests will fail like this so bail out
MacOSError::throwMe(rc);
}
if (disabled) {
if (latentID == 0) {
latentID = id;
if (label)
latentLabel = label;
}
continue; // the loop
}
if (SYSPOLICY_ASSESS_OUTCOME_ACCEPT_ENABLED() || SYSPOLICY_ASSESS_OUTCOME_DENY_ENABLED()) {
if (allow)
SYSPOLICY_ASSESS_OUTCOME_ACCEPT(cfString(path).c_str(), type, label, NULL);
else
SYSPOLICY_ASSESS_OUTCOME_DENY(cfString(path).c_str(), type, label, NULL);
}
// not adding to the object cache - we could, but it's not likely to be worth it
cfadd(result, "{%O=%B}", kSecAssessmentAssessmentVerdict, allow);
addAuthority(result, label, id);
return;
}
}
if (SYSPOLICY_ASSESS_OUTCOME_DEFAULT_ENABLED())
SYSPOLICY_ASSESS_OUTCOME_DEFAULT(cfString(path).c_str(), type, latentLabel.c_str(), NULL);
// no applicable authority. Deny by default
cfadd(result, "{%O=#F}", kSecAssessmentAssessmentVerdict);
addAuthority(result, latentLabel.c_str(), latentID);
}
void PolicyEngine::evaluateCodeItem(SecStaticCodeRef code, CFURLRef path, AuthorityType type, SecAssessmentFlags flags, bool nested, CFMutableDictionaryRef result)
{
SQLite::Statement query(*this,
"SELECT allow, requirement, id, label, expires, flags, disabled, filter_unsigned, remarks FROM scan_authority"
" WHERE type = :type"
" ORDER BY priority DESC;");
query.bind(":type").integer(type);
SQLite3::int64 latentID = 0; // first (highest priority) disabled matching ID
std::string latentLabel; // ... and associated label, if any
while (query.nextRow()) {
bool allow = int(query[0]);
const char *reqString = query[1];
SQLite3::int64 id = query[2];
const char *label = query[3];
double expires = query[4];
sqlite3_int64 ruleFlags = query[5];
SQLite3::int64 disabled = query[6];
// const char *filter = query[7];
// const char *remarks = query[8];
CFRef<SecRequirementRef> requirement;
MacOSError::check(SecRequirementCreateWithString(CFTempString(reqString), kSecCSDefaultFlags, &requirement.aref()));
switch (OSStatus rc = SecStaticCodeCheckValidity(code, kSecCSBasicValidateOnly, requirement)) {
case errSecSuccess:
break; // rule match; process below
case errSecCSReqFailed:
continue; // rule does not apply
case errSecCSVetoed:
return; // nested code has failed to pass
default:
MacOSError::throwMe(rc); // general error; pass to caller
}
// if this rule is disabled, skip it but record the first matching one for posterity
if (disabled && latentID == 0) {
latentID = id;
latentLabel = label ? label : "";
continue;
}
// current rule is first rule (in priority order) that matched. Apply it
if (nested) // success, nothing to record
return;
CFRef<CFDictionaryRef> info; // as needed
if (flags & kSecAssessmentFlagRequestOrigin) {
if (!info)
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
if (CFArrayRef chain = CFArrayRef(CFDictionaryGetValue(info, kSecCodeInfoCertificates)))
setOrigin(chain, result);
}
if (!(ruleFlags & kAuthorityFlagInhibitCache) && !(flags & kSecAssessmentFlagNoCache)) { // cache inhibit
if (!info)
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
if (SecTrustRef trust = SecTrustRef(CFDictionaryGetValue(info, kSecCodeInfoTrust))) {
CFRef<CFDictionaryRef> xinfo;
MacOSError::check(SecTrustCopyExtendedResult(trust, &xinfo.aref()));
if (CFDateRef limit = CFDateRef(CFDictionaryGetValue(xinfo, kSecTrustExpirationDate))) {
this->recordOutcome(code, allow, type, min(expires, dateToJulian(limit)), id);
}
}
}
if (allow) {
if (SYSPOLICY_ASSESS_OUTCOME_ACCEPT_ENABLED()) {
if (!info)
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
CFDataRef cdhash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
SYSPOLICY_ASSESS_OUTCOME_ACCEPT(cfString(path).c_str(), type, label, cdhash ? CFDataGetBytePtr(cdhash) : NULL);
}
} else {
if (SYSPOLICY_ASSESS_OUTCOME_DENY_ENABLED() || SYSPOLICY_RECORDER_MODE_ENABLED()) {
if (!info)
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
CFDataRef cdhash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
std::string cpath = cfString(path);
const void *hashp = cdhash ? CFDataGetBytePtr(cdhash) : NULL;
SYSPOLICY_ASSESS_OUTCOME_DENY(cpath.c_str(), type, label, hashp);
SYSPOLICY_RECORDER_MODE(cpath.c_str(), type, label, hashp, recorder_code_untrusted);
}
}
cfadd(result, "{%O=%B}", kSecAssessmentAssessmentVerdict, allow);
addAuthority(flags, result, label, id);
return;
}
// no applicable authority (but signed, perhaps temporarily). Deny by default
CFRef<CFDictionaryRef> info;
MacOSError::check(SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref()));
if (flags & kSecAssessmentFlagRequestOrigin) {
if (CFArrayRef chain = CFArrayRef(CFDictionaryGetValue(info, kSecCodeInfoCertificates)))
setOrigin(chain, result);
}
if (SYSPOLICY_ASSESS_OUTCOME_DEFAULT_ENABLED() || SYSPOLICY_RECORDER_MODE_ENABLED()) {
CFDataRef cdhash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
const void *hashp = cdhash ? CFDataGetBytePtr(cdhash) : NULL;
std::string cpath = cfString(path);
SYSPOLICY_ASSESS_OUTCOME_DEFAULT(cpath.c_str(), type, latentLabel.c_str(), hashp);
SYSPOLICY_RECORDER_MODE(cpath.c_str(), type, latentLabel.c_str(), hashp, 0);
}
if (!(flags & kSecAssessmentFlagNoCache))
this->recordOutcome(code, false, type, this->julianNow() + NEGATIVE_HOLD, latentID);
cfadd(result, "{%O=%B}", kSecAssessmentAssessmentVerdict, false);
addAuthority(flags, result, latentLabel.c_str(), latentID);
}
