policyengine.cpp   [plain text]

/*
 * Copyright (c) 2011-2012 Apple Inc. All Rights Reserved.
 * 
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
#include "policyengine.h"
#include "xar++.h"
#include "quarantine++.h"
#include "codesigning_dtrace.h"
#include <security_utilities/cfmunge.h>
#include <Security/Security.h>
#include <Security/SecCodePriv.h>
#include <Security/SecRequirementPriv.h>
#include <Security/SecPolicyPriv.h>
#include <Security/SecTrustPriv.h>
#include <Security/SecCodeSigner.h>
#include <Security/cssmapplePriv.h>
#include <security_utilities/unix++.h>
#include <notify.h>

#include "diskrep.h"
#include "codedirectory.h"
#include "csutilities.h"
#include "StaticCode.h"

#include <CoreServices/CoreServicesPriv.h>
#include "SecCodePriv.h"
#undef check // Macro! Yech.

extern "C" {
#include <OpenScriptingUtilPriv.h>
}


namespace Security {
namespace CodeSigning {

static const double NEGATIVE_HOLD = 60.0/86400;	// 60 seconds to cache negative outcomes

static const char RECORDER_DIR[] = "/tmp/gke-";		// recorder mode destination for detached signatures
enum {
	recorder_code_untrusted = 0,		// signed but untrusted
	recorder_code_adhoc = 1,			// unsigned; signature recorded
	recorder_code_unable = 2,			// unsigned; unable to record signature
};


static void authorizeUpdate(SecAssessmentFlags flags, CFDictionaryRef context);
static void normalizeTarget(CFRef<CFTypeRef> &target, CFDictionary &context, std::string *signUnsigned = NULL);
static bool codeInvalidityExceptions(SecStaticCodeRef code, CFMutableDictionaryRef result);
static CFTypeRef installerPolicy() CF_RETURNS_RETAINED;


//
// Core structure
//
PolicyEngine::PolicyEngine()
	: PolicyDatabase(NULL, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE)
{
}

PolicyEngine::~PolicyEngine()
{ }


//
// Top-level evaluation driver
//
void PolicyEngine::evaluate(CFURLRef path, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context, CFMutableDictionaryRef result)
{
	// update GKE
	installExplicitSet(gkeAuthFile, gkeSigsFile);

	switch (type) {
	case kAuthorityExecute:
		evaluateCode(path, kAuthorityExecute, flags, context, result);
		break;
	case kAuthorityInstall:
		evaluateInstall(path, flags, context, result);
		break;
	case kAuthorityOpenDoc:
		evaluateDocOpen(path, flags, context, result);
		break;
	default:
		MacOSError::throwMe(errSecCSInvalidAttributeValues);
		break;
	}
}


//
// Whitelist pre-screen processing.
// Whitelist-matching unsigned code is expensive since we have to generate a full code signature
// just to see if we match a whitelist authority entry. This class generates a light(er)-weight
// prescreen and matches it against a hint in an authority record generated from the (detached recorded)
// code signature at time of whitelist recording.
// This is just a heuristic to cheaply rule out guaranteed mismatches. When in doubt, we go ahead
// and do the full work.
//
class WhitelistPrescreen {
public:
	WhitelistPrescreen(SecStaticCodeRef code)
		: mRep(SecStaticCode::requiredStatic(code)->diskRep()) { }

	bool reject(const char *screen, const char *remarks);
	
private:
	std::string create(char type, SHA1 &hash);

	RefPointer<DiskRep> mRep;	// DiskRep representing the code
	std::string mScreen;	// calculated screen (on demand)
};

bool WhitelistPrescreen::reject(const char *screen, const char *remarks)
{
	if (!screen) {	// authority record has no screen to match - apply heuristic
		if (remarks && mRep->mainExecutablePath() != remarks)	// not an allow record (or moved)
			return true;
		else
			return false;	// can't rule out; proceed
	}

	if (mScreen.empty()) {
		if (CFRef<CFDataRef> info = mRep->component(cdInfoSlot)) {
			SHA1 hash;
			hash.update(CFDataGetBytePtr(info), CFDataGetLength(info));
			mScreen = create('I', hash);
		} else if (mRep->mainExecutableImage()) {
			mScreen = "N";
		} else {
			SHA1 hash;
			hashFileData(mRep->mainExecutablePath().c_str(), &hash);
			mScreen = create('M', hash);
		}
	}

	return screen != mScreen;
}

std::string WhitelistPrescreen::create(char type, SHA1 &hash)
{
	SHA1::Digest digest;
	hash.finish(digest);
	char buffer[2*SHA1::digestLength + 2] = { type };
	for (size_t n = 0; n < SHA1::digestLength; n++)
		sprintf(buffer + 1 + 2*n, "%02.2x", digest[n]);
	return buffer;
}


//
// 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);
}


//
// Create a suitable policy array for verification of installer signatures.
//
static SecPolicyRef makeCRLPolicy()
{
	CFRef<SecPolicyRef> policy;
	MacOSError::check(SecPolicyCopy(CSSM_CERT_X_509v3, &CSSMOID_APPLE_TP_REVOCATION_CRL, &policy.aref()));
	CSSM_APPLE_TP_CRL_OPTIONS options;
	memset(&options, 0, sizeof(options));
	options.Version = CSSM_APPLE_TP_CRL_OPTS_VERSION;
	options.CrlFlags = CSSM_TP_ACTION_FETCH_CRL_FROM_NET | CSSM_TP_ACTION_CRL_SUFFICIENT;
	CSSM_DATA optData = { sizeof(options), (uint8 *)&options };
	MacOSError::check(SecPolicySetValue(policy, &optData));
	return policy.yield();
}

static SecPolicyRef makeOCSPPolicy()
{
	CFRef<SecPolicyRef> policy;
	MacOSError::check(SecPolicyCopy(CSSM_CERT_X_509v3, &CSSMOID_APPLE_TP_REVOCATION_OCSP, &policy.aref()));
	CSSM_APPLE_TP_OCSP_OPTIONS options;
	memset(&options, 0, sizeof(options));
	options.Version = CSSM_APPLE_TP_OCSP_OPTS_VERSION;
	options.Flags = CSSM_TP_ACTION_OCSP_SUFFICIENT;
	CSSM_DATA optData = { sizeof(options), (uint8 *)&options };
	MacOSError::check(SecPolicySetValue(policy, &optData));
	return policy.yield();
}

static CFTypeRef installerPolicy()
{
	CFRef<SecPolicyRef> base = SecPolicyCreateBasicX509();
	CFRef<SecPolicyRef> crl = makeCRLPolicy();
	CFRef<SecPolicyRef> ocsp = makeOCSPPolicy();
	return makeCFArray(3, base.get(), crl.get(), ocsp.get());
}


//
// LaunchServices-layer document open.
// We don't cache those at present. If we ever do, we need to authenticate CoreServicesUIAgent as the source of its risk assessment.
//
void PolicyEngine::evaluateDocOpen(CFURLRef path, SecAssessmentFlags flags, CFDictionaryRef context, CFMutableDictionaryRef result)
{
	if (context) {
		if (CFStringRef riskCategory = CFStringRef(CFDictionaryGetValue(context, kLSDownloadRiskCategoryKey))) {
			FileQuarantine qtn(cfString(path).c_str());

			if (CFEqual(riskCategory, kLSRiskCategorySafe)
				|| CFEqual(riskCategory, kLSRiskCategoryNeutral)
				|| CFEqual(riskCategory, kLSRiskCategoryUnknown)
				|| CFEqual(riskCategory, kLSRiskCategoryMayContainUnsafeExecutable)) {
				cfadd(result, "{%O=#T}", kSecAssessmentAssessmentVerdict);
				addAuthority(result, "_XProtect");
			} else if (qtn.flag(QTN_FLAG_HARD)) {
				MacOSError::throwMe(errSecCSFileHardQuarantined);
			} else if (qtn.flag(QTN_FLAG_ASSESSMENT_OK)) {
				cfadd(result, "{%O=#T}", kSecAssessmentAssessmentVerdict);
				addAuthority(result, "Prior Assessment");
			} else if (!overrideAssessment()) {		// no need to do more work if we're off
				try {
					evaluateCode(path, kAuthorityExecute, flags, context, result, false);
				} catch (...) {
					// some documents can't be code signed, so this may be quite benign
				}
			}
			if (CFDictionaryGetValue(result, kSecAssessmentAssessmentVerdict) == NULL) {	// no code signature to help us out
			   cfadd(result, "{%O=#F}", kSecAssessmentAssessmentVerdict);
			   addAuthority(result, "_XProtect");
			}
			addToAuthority(result, kLSDownloadRiskCategoryKey, riskCategory);
			return;
		}
	}
	// insufficient information from LS - deny by default
	cfadd(result, "{%O=#F}", kSecAssessmentAssessmentVerdict);
	addAuthority(result, "Insufficient Context");
}


//
// Result-creation helpers
//
void PolicyEngine::addAuthority(CFMutableDictionaryRef parent, const char *label, SQLite::int64 row, CFTypeRef cacheInfo)
{
	CFRef<CFMutableDictionaryRef> auth = makeCFMutableDictionary();
	if (label && label[0])
		cfadd(auth, "{%O=%s}", kSecAssessmentAssessmentSource, label);
	if (row)
		CFDictionaryAddValue(auth, kSecAssessmentAssessmentAuthorityRow, CFTempNumber(row));
	if (overrideAssessment())
		CFDictionaryAddValue(auth, kSecAssessmentAssessmentAuthorityOverride, kDisabledOverride);
	if (cacheInfo)
		CFDictionaryAddValue(auth, kSecAssessmentAssessmentFromCache, cacheInfo);
	CFDictionaryAddValue(parent, kSecAssessmentAssessmentAuthority, auth);
}

void PolicyEngine::addToAuthority(CFMutableDictionaryRef parent, CFStringRef key, CFTypeRef value)
{
	CFMutableDictionaryRef authority = CFMutableDictionaryRef(CFDictionaryGetValue(parent, kSecAssessmentAssessmentAuthority));
	assert(authority);
	CFDictionaryAddValue(authority, key, value);
}


//
// Add a rule to the policy database
//
CFDictionaryRef PolicyEngine::add(CFTypeRef inTarget, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context)
{
	// default type to execution
	if (type == kAuthorityInvalid)
		type = kAuthorityExecute;

	authorizeUpdate(flags, context);
	CFDictionary ctx(context, errSecCSInvalidAttributeValues);
	CFCopyRef<CFTypeRef> target = inTarget;
	CFRef<CFDataRef> bookmark = NULL;
	std::string filter_unsigned;

	switch (type) {
	case kAuthorityExecute:
		normalizeTarget(target, ctx, &filter_unsigned);
		// bookmarks are untrusted and just a hint to callers
		bookmark = ctx.get<CFDataRef>(kSecAssessmentRuleKeyBookmark);
		break;
	case kAuthorityInstall:
		if (inTarget && CFGetTypeID(inTarget) == CFURLGetTypeID()) {
			// no good way to turn an installer file into a requirement. Pretend to succeeed so caller proceeds
			return cfmake<CFDictionaryRef>("{%O=%O}", kSecAssessmentAssessmentAuthorityOverride, CFSTR("virtual install"));
		}
		break;
	case kAuthorityOpenDoc:
		// handle document-open differently: use quarantine flags for whitelisting
		if (!target || CFGetTypeID(target) != CFURLGetTypeID())	// can only "add" file paths
			MacOSError::throwMe(errSecCSInvalidObjectRef);
		try {
			std::string spath = cfString(target.as<CFURLRef>());
			FileQuarantine qtn(spath.c_str());
			qtn.setFlag(QTN_FLAG_ASSESSMENT_OK);
			qtn.applyTo(spath.c_str());
		} catch (const CommonError &error) {
			// could not set quarantine flag - report qualified success
			return cfmake<CFDictionaryRef>("{%O=%O,'assessment:error'=%d}",
				kSecAssessmentAssessmentAuthorityOverride, CFSTR("error setting quarantine"), error.osStatus());
		} catch (...) {
			return cfmake<CFDictionaryRef>("{%O=%O}", kSecAssessmentAssessmentAuthorityOverride, CFSTR("unable to set quarantine"));
		}
		return NULL;
	}
	
	// if we now have anything else, we're busted
	if (!target || CFGetTypeID(target) != SecRequirementGetTypeID())
		MacOSError::throwMe(errSecCSInvalidObjectRef);

	double priority = 0;
	string label;
	bool allow = true;
	double expires = never;
	string remarks;
	
	if (CFNumberRef pri = ctx.get<CFNumberRef>(kSecAssessmentUpdateKeyPriority))
		CFNumberGetValue(pri, kCFNumberDoubleType, &priority);
	if (CFStringRef lab = ctx.get<CFStringRef>(kSecAssessmentUpdateKeyLabel))
		label = cfString(lab);
	if (CFDateRef time = ctx.get<CFDateRef>(kSecAssessmentUpdateKeyExpires))
		// we're using Julian dates here; convert from CFDate
		expires = dateToJulian(time);
	if (CFBooleanRef allowing = ctx.get<CFBooleanRef>(kSecAssessmentUpdateKeyAllow))
		allow = allowing == kCFBooleanTrue;
	if (CFStringRef rem = ctx.get<CFStringRef>(kSecAssessmentUpdateKeyRemarks))
		remarks = cfString(rem);

	CFRef<CFStringRef> requirementText;
	MacOSError::check(SecRequirementCopyString(target.as<SecRequirementRef>(), kSecCSDefaultFlags, &requirementText.aref()));
	SQLite::Transaction xact(*this, SQLite3::Transaction::deferred, "add_rule");
	SQLite::Statement insert(*this,
		"INSERT INTO authority (type, allow, requirement, priority, label, expires, filter_unsigned, remarks)"
		"	VALUES (:type, :allow, :requirement, :priority, :label, :expires, :filter_unsigned, :remarks);");
	insert.bind(":type").integer(type);
	insert.bind(":allow").integer(allow);
	insert.bind(":requirement") = requirementText.get();
	insert.bind(":priority") = priority;
	if (!label.empty())
		insert.bind(":label") = label;
	insert.bind(":expires") = expires;
	insert.bind(":filter_unsigned") = filter_unsigned.empty() ? NULL : filter_unsigned.c_str();
	if (!remarks.empty())
		insert.bind(":remarks") = remarks;
	insert.execute();
	SQLite::int64 newRow = this->lastInsert();
	if (bookmark) {
		SQLite::Statement bi(*this, "INSERT INTO bookmarkhints (bookmark, authority) VALUES (:bookmark, :authority)");
		bi.bind(":bookmark") = CFDataRef(bookmark);
		bi.bind(":authority").integer(newRow);
		bi.execute();
	}
	this->purgeObjects(priority);
	xact.commit();
	notify_post(kNotifySecAssessmentUpdate);
	return cfmake<CFDictionaryRef>("{%O=%d}", kSecAssessmentUpdateKeyRow, newRow);
}


CFDictionaryRef PolicyEngine::remove(CFTypeRef target, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context)
{
	if (type == kAuthorityOpenDoc) {
		// handle document-open differently: use quarantine flags for whitelisting
		authorizeUpdate(flags, context);
		if (!target || CFGetTypeID(target) != CFURLGetTypeID())
			MacOSError::throwMe(errSecCSInvalidObjectRef);
		std::string spath = cfString(CFURLRef(target)).c_str();
		FileQuarantine qtn(spath.c_str());
		qtn.clearFlag(QTN_FLAG_ASSESSMENT_OK);
		qtn.applyTo(spath.c_str());
		return NULL;
	}
	return manipulateRules("DELETE FROM authority", target, type, flags, context);
}

CFDictionaryRef PolicyEngine::enable(CFTypeRef target, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context)
{
	return manipulateRules("UPDATE authority SET disabled = 0", target, type, flags, context);
}

CFDictionaryRef PolicyEngine::disable(CFTypeRef target, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context)
{
	return manipulateRules("UPDATE authority SET disabled = 1", target, type, flags, context);
}

CFDictionaryRef PolicyEngine::find(CFTypeRef target, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context)
{
	SQLite::Statement query(*this);
	selectRules(query, "SELECT scan_authority.id, scan_authority.type, scan_authority.requirement, scan_authority.allow, scan_authority.label, scan_authority.priority, scan_authority.remarks, scan_authority.expires, scan_authority.disabled, bookmarkhints.bookmark FROM scan_authority LEFT OUTER JOIN bookmarkhints ON scan_authority.id = bookmarkhints.authority",
		"scan_authority", target, type, flags, context,
		" ORDER BY priority DESC");
	CFRef<CFMutableArrayRef> found = makeCFMutableArray(0);
	while (query.nextRow()) {
		SQLite::int64 id = query[0];
		int type = int(query[1]);
		const char *requirement = query[2];
		int allow = int(query[3]);
		const char *label = query[4];
		double priority = query[5];
		const char *remarks = query[6];
		double expires = query[7];
		int disabled = int(query[8]);
		CFRef<CFDataRef> bookmark = query[9].data();
		CFRef<CFMutableDictionaryRef> rule = makeCFMutableDictionary(5,
			kSecAssessmentRuleKeyID, CFTempNumber(id).get(),
			kSecAssessmentRuleKeyType, CFRef<CFStringRef>(typeNameFor(type)).get(),
			kSecAssessmentRuleKeyRequirement, CFTempString(requirement).get(),
			kSecAssessmentRuleKeyAllow, allow ? kCFBooleanTrue : kCFBooleanFalse,
			kSecAssessmentRuleKeyPriority, CFTempNumber(priority).get()
			);
		if (label)
			CFDictionaryAddValue(rule, kSecAssessmentRuleKeyLabel, CFTempString(label));
		if (remarks)
			CFDictionaryAddValue(rule, kSecAssessmentRuleKeyRemarks, CFTempString(remarks));
		if (expires != never)
			CFDictionaryAddValue(rule, kSecAssessmentRuleKeyExpires, CFRef<CFDateRef>(julianToDate(expires)));
		if (disabled)
			CFDictionaryAddValue(rule, kSecAssessmentRuleKeyDisabled, CFTempNumber(disabled));
		if (bookmark)
			CFDictionaryAddValue(rule, kSecAssessmentRuleKeyBookmark, bookmark);
		CFArrayAppendValue(found, rule);
	}
	if (CFArrayGetCount(found) == 0)
		MacOSError::throwMe(errSecCSNoMatches);
	return cfmake<CFDictionaryRef>("{%O=%O}", kSecAssessmentUpdateKeyFound, found.get());
}


CFDictionaryRef PolicyEngine::update(CFTypeRef target, SecAssessmentFlags flags, CFDictionaryRef context)
{
	// update GKE
	installExplicitSet(gkeAuthFile, gkeSigsFile);

	AuthorityType type = typeFor(context, kAuthorityInvalid);
	CFStringRef edit = CFStringRef(CFDictionaryGetValue(context, kSecAssessmentContextKeyUpdate));
	CFDictionaryRef result;
	if (CFEqual(edit, kSecAssessmentUpdateOperationAdd))
		result = this->add(target, type, flags, context);
	else if (CFEqual(edit, kSecAssessmentUpdateOperationRemove))
		result = this->remove(target, type, flags, context);
	else if (CFEqual(edit, kSecAssessmentUpdateOperationEnable))
		result = this->enable(target, type, flags, context);
	else if (CFEqual(edit, kSecAssessmentUpdateOperationDisable))
		result = this->disable(target, type, flags, context);
	else if (CFEqual(edit, kSecAssessmentUpdateOperationFind))
		result = this->find(target, type, flags, context);
	else
		MacOSError::throwMe(errSecCSInvalidAttributeValues);
	if (result == NULL)
		result = makeCFDictionary(0);		// success, no details
	return result;
}


//
// Construct and prepare an SQL query on the authority table, operating on some set of existing authority records.
// In essence, this appends a suitable WHERE clause to the stanza passed and prepares it on the statement given.
//
void PolicyEngine::selectRules(SQLite::Statement &action, std::string phrase, std::string table,
	CFTypeRef inTarget, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context, std::string suffix /* = "" */)
{
	CFDictionary ctx(context, errSecCSInvalidAttributeValues);
	CFCopyRef<CFTypeRef> target = inTarget;
	std::string filter_unsigned;	// ignored; used just to trigger ad-hoc signing
	normalizeTarget(target, ctx, &filter_unsigned);

	string label;
	if (CFStringRef lab = ctx.get<CFStringRef>(kSecAssessmentUpdateKeyLabel))
		label = cfString(CFStringRef(lab));

	if (!target) {
		if (label.empty()) {
			if (type == kAuthorityInvalid) {
				action.query(phrase + suffix);
			} else {
				action.query(phrase + " WHERE " + table + ".type = :type" + suffix);
				action.bind(":type").integer(type);
			}
		} else {	// have label
			if (type == kAuthorityInvalid) {
				action.query(phrase + " WHERE " + table + ".label = :label" + suffix);
			} else {
				action.query(phrase + " WHERE " + table + ".type = :type AND " + table + ".label = :label" + suffix);
				action.bind(":type").integer(type);
			}
			action.bind(":label") = label;
		}
	} else if (CFGetTypeID(target) == CFNumberGetTypeID()) {
		action.query(phrase + " WHERE " + table + ".id = :id" + suffix);
		action.bind(":id").integer(cfNumber<uint64_t>(target.as<CFNumberRef>()));
	} else if (CFGetTypeID(target) == SecRequirementGetTypeID()) {
		if (type == kAuthorityInvalid)
			type = kAuthorityExecute;
		CFRef<CFStringRef> requirementText;
		MacOSError::check(SecRequirementCopyString(target.as<SecRequirementRef>(), kSecCSDefaultFlags, &requirementText.aref()));
		action.query(phrase + " WHERE " + table + ".type = :type AND " + table + ".requirement = :requirement" + suffix);
		action.bind(":type").integer(type);
		action.bind(":requirement") = requirementText.get();
	} else
		MacOSError::throwMe(errSecCSInvalidObjectRef);
}


//
// Execute an atomic change to existing records in the authority table.
//
CFDictionaryRef PolicyEngine::manipulateRules(const std::string &stanza,
	CFTypeRef inTarget, AuthorityType type, SecAssessmentFlags flags, CFDictionaryRef context)
{
	SQLite::Transaction xact(*this, SQLite3::Transaction::deferred, "rule_change");
	SQLite::Statement action(*this);
	authorizeUpdate(flags, context);
	selectRules(action, stanza, "authority", inTarget, type, flags, context);
	action.execute();
	unsigned int changes = this->changes();	// latch change count
	// We MUST purge objects with priority <= MAX(priority of any changed rules);
	// but for now we just get lazy and purge them ALL.
	if (changes) {
		this->purgeObjects(1.0E100);
		xact.commit();
		notify_post(kNotifySecAssessmentUpdate);
		return cfmake<CFDictionaryRef>("{%O=%d}", kSecAssessmentUpdateKeyCount, changes);
	}
	// no change; return an error
	MacOSError::throwMe(errSecCSNoMatches);
}


//
// Fill in extra information about the originator of cryptographic credentials found - if any
//
void PolicyEngine::setOrigin(CFArrayRef chain, CFMutableDictionaryRef result)
{
	if (chain)
		if (CFArrayGetCount(chain) > 0)
			if (SecCertificateRef leaf = SecCertificateRef(CFArrayGetValueAtIndex(chain, 0)))
				if (CFStringRef summary = SecCertificateCopyLongDescription(NULL, leaf, NULL)) {
					CFDictionarySetValue(result, kSecAssessmentAssessmentOriginator, summary);
					CFRelease(summary);
				}
}


//
// Take an assessment outcome and record it in the object cache
//
void PolicyEngine::recordOutcome(SecStaticCodeRef code, bool allow, AuthorityType type, double expires, SQLite::int64 authority)
{
	CFRef<CFDictionaryRef> info;
	MacOSError::check(SecCodeCopySigningInformation(code, kSecCSDefaultFlags, &info.aref()));
	CFDataRef cdHash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
	assert(cdHash);		// was signed
	CFRef<CFURLRef> path;
	MacOSError::check(SecCodeCopyPath(code, kSecCSDefaultFlags, &path.aref()));
	assert(expires);
	SQLite::Transaction xact(*this, SQLite3::Transaction::deferred, "caching");
	SQLite::Statement insert(*this,
		"INSERT OR REPLACE INTO object (type, allow, hash, expires, path, authority)"
		"	VALUES (:type, :allow, :hash, :expires, :path,"
		"	CASE :authority WHEN 0 THEN (SELECT id FROM authority WHERE label = 'No Matching Rule') ELSE :authority END"
		"	);");
	insert.bind(":type").integer(type);
	insert.bind(":allow").integer(allow);
	insert.bind(":hash") = cdHash;
	insert.bind(":expires") = expires;
	insert.bind(":path") = cfString(path);
	insert.bind(":authority").integer(authority);
	insert.execute();
	xact.commit();
}


//
// Perform update authorization processing.
// Throws an exception if authorization is denied.
//
static void authorizeUpdate(SecAssessmentFlags flags, CFDictionaryRef context)
{
	AuthorizationRef authorization = NULL;
	
	if (context)
		if (CFTypeRef authkey = CFDictionaryGetValue(context, kSecAssessmentUpdateKeyAuthorization))
			if (CFGetTypeID(authkey) == CFDataGetTypeID()) {
				CFDataRef authdata = CFDataRef(authkey);
				MacOSError::check(AuthorizationCreateFromExternalForm((AuthorizationExternalForm *)CFDataGetBytePtr(authdata), &authorization));
			}
	if (authorization == NULL)
		MacOSError::check(AuthorizationCreate(NULL, NULL, kAuthorizationFlagDefaults, &authorization));
	
	AuthorizationItem right[] = {
		{ "com.apple.security.assessment.update", 0, NULL, 0 }
	};
	AuthorizationRights rights = { sizeof(right) / sizeof(right[0]), right };
	MacOSError::check(AuthorizationCopyRights(authorization, &rights, NULL,
		kAuthorizationFlagExtendRights | kAuthorizationFlagInteractionAllowed, NULL));
	
	MacOSError::check(AuthorizationFree(authorization, kAuthorizationFlagDefaults));
}


//
// Perform common argument normalizations for update operations
//
static void normalizeTarget(CFRef<CFTypeRef> &target, CFDictionary &context, std::string *signUnsigned)
{
	// turn CFURLs into (designated) SecRequirements
	if (target && CFGetTypeID(target) == CFURLGetTypeID()) {
		CFRef<SecStaticCodeRef> code;
		MacOSError::check(SecStaticCodeCreateWithPath(target.as<CFURLRef>(), kSecCSDefaultFlags, &code.aref()));
		switch (OSStatus rc = SecCodeCopyDesignatedRequirement(code, kSecCSDefaultFlags, (SecRequirementRef *)&target.aref())) {
		case noErr: {
			// use the *default* DR to avoid unreasonably wide DRs opening up Gatekeeper to attack
			CFRef<CFDictionaryRef> info;
			MacOSError::check(SecCodeCopySigningInformation(code, kSecCSRequirementInformation, &info.aref()));
			target = CFDictionaryGetValue(info, kSecCodeInfoImplicitDesignatedRequirement);
			}
			break;
		case errSecCSUnsigned:
			if (signUnsigned) {
				// Ad-hoc sign the code temporarily so we can get its code requirement
				CFRef<CFDataRef> signature = CFDataCreateMutable(NULL, 0);
				CFRef<SecCodeSignerRef> signer;
				CFTemp<CFDictionaryRef> arguments("{%O=%O, %O=#N}", kSecCodeSignerDetached, signature.get(), kSecCodeSignerIdentity);
				MacOSError::check(SecCodeSignerCreate(arguments, kSecCSDefaultFlags, &signer.aref()));
				MacOSError::check(SecCodeSignerAddSignature(signer, code, kSecCSDefaultFlags));
				MacOSError::check(SecCodeSetDetachedSignature(code, signature, kSecCSDefaultFlags));
				MacOSError::check(SecCodeCopyDesignatedRequirement(code, kSecCSDefaultFlags, (SecRequirementRef *)&target.aref()));
				CFRef<CFDictionaryRef> info;
				MacOSError::check(SecCodeCopySigningInformation(code, kSecCSInternalInformation, &info.aref()));
				if (CFDataRef cdData = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoCodeDirectory)))
					*signUnsigned = ((const CodeDirectory *)CFDataGetBytePtr(cdData))->screeningCode();
				break;
			}
			MacOSError::check(rc);
		case errSecCSSignatureFailed:
			// recover certain cases of broken signatures (well, try)
			if (codeInvalidityExceptions(code, NULL)) {
				// Ad-hoc sign the code in place (requiring a writable subject). This requires root privileges.
				CFRef<SecCodeSignerRef> signer;
				CFTemp<CFDictionaryRef> arguments("{%O=#N}", kSecCodeSignerIdentity);
				MacOSError::check(SecCodeSignerCreate(arguments, kSecCSDefaultFlags, &signer.aref()));
				MacOSError::check(SecCodeSignerAddSignature(signer, code, kSecCSDefaultFlags));
				MacOSError::check(SecCodeCopyDesignatedRequirement(code, kSecCSDefaultFlags, (SecRequirementRef *)&target.aref()));
				break;
			}
			MacOSError::check(rc);
		default:
			MacOSError::check(rc);
		}
		if (context.get(kSecAssessmentUpdateKeyRemarks) == NULL)	{
			// no explicit remarks; add one with the path
			CFRef<CFURLRef> path;
			MacOSError::check(SecCodeCopyPath(code, kSecCSDefaultFlags, &path.aref()));
			CFMutableDictionaryRef dict = makeCFMutableDictionary(context.get());
			CFDictionaryAddValue(dict, kSecAssessmentUpdateKeyRemarks, CFTempString(cfString(path)));
			context.take(dict);
		}
	}
}


//
// Process special overrides for invalidly signed code.
// This is the (hopefully minimal) concessions we make to keep hurting our customers
// for our own prior mistakes...
//
static bool codeInvalidityExceptions(SecStaticCodeRef code, CFMutableDictionaryRef result)
{
	if (OSAIsRecognizedExecutableURL) {
		CFRef<CFDictionaryRef> info;
		MacOSError::check(SecCodeCopySigningInformation(code, kSecCSDefaultFlags, &info.aref()));
		if (CFURLRef executable = CFURLRef(CFDictionaryGetValue(info, kSecCodeInfoMainExecutable))) {
			SInt32 error;
			if (OSAIsRecognizedExecutableURL(executable, &error)) {
				if (result)
					CFDictionaryAddValue(result,
						kSecAssessmentAssessmentAuthorityOverride, CFSTR("ignoring known invalid applet signature"));
				return true;
			}
		}
	}
	return false;
}


} // end namespace CodeSigning
} // end namespace Security