Security-57740.60.18.tar.gz

[apple/security.git] / OSX / libsecurity_keychain / lib / SecTrustSettings.cpp

/*
 * Copyright (c) 2005,2011-2016 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@
 */

/*
 * SecTrustSettings.cpp - Public interface for manipulation of Trust Settings.
 *
 */

#include "SecBridge.h"
#include "SecCertificatePriv.h"
#include "SecTrustSettings.h"
#include "SecTrustSettingsPriv.h"
#include "SecTrustSettingsCertificates.h"
#include "TrustSettingsUtils.h"
#include "TrustSettings.h"
#include "TrustSettingsSchema.h"
#include "TrustKeychains.h"
#include "Trust.h"
#include "SecKeychainPriv.h"
#include "Globals.h"
#include <security_utilities/threading.h>
#include <security_utilities/globalizer.h>
#include <security_utilities/errors.h>
#include <security_cdsa_utilities/cssmerrors.h>
#include <security_utilities/logging.h>
#include <security_utilities/debugging.h>
#include <security_utilities/simpleprefs.h>
#include <securityd_client/dictionary.h>
#include <securityd_client/ssclient.h>
#include <assert.h>
#include <dlfcn.h>
#include <libproc.h>
#include <syslog.h>
#include <vector>
#include <CommonCrypto/CommonDigest.h>
#include <CoreFoundation/CFPreferences.h>
#include <utilities/SecCFRelease.h>

#define trustSettingsDbg(args...)       secinfo("trustSettings", ## args)

/*
 * Ideally we'd like to implement our own lock to protect the state of the cert stores
 * without grabbing the global Sec API lock, but we deal with SecCFObjects, so we'll have
 * to bite the bullet and grab the big lock. We also have our own lock protecting the
 * global trust settings cache which is also used by the keychain callback function
 * (which does not grab the Sec API lock).
 */

#define BEGIN_RCSAPI    \
        OSStatus __secapiresult; \
        try {
#define END_RCSAPI              \
                __secapiresult=errSecSuccess; \
        } \
        catch (const MacOSError &err) { __secapiresult=err.osStatus(); } \
        catch (const CommonError &err) { __secapiresult=SecKeychainErrFromOSStatus(err.osStatus()); } \
        catch (const std::bad_alloc &) { __secapiresult=errSecAllocate; } \
        catch (...) { __secapiresult=errSecInternalComponent; } \
        return __secapiresult;

#define END_RCSAPI0             \
        catch (...) {} \
        return;


#pragma mark --- TrustSettings preferences ---

/*
 * If Colonel Klink wants to disable user-level Trust Settings, he'll have
 * to restart the apps which will be affected after he does so. We are not
 * going to consult system prefs every time we do a cert evaluation. We
 * consult it once per process and cache the results here.
 */
static bool tsUserTrustDisableValid = false;    /* true once we consult prefs */
static bool tsUserTrustDisable = false;                 /* the cached value */

/*
 * Determine whether user-level Trust Settings disabled.
 */
static bool tsUserTrustSettingsDisabled()
{
        if(tsUserTrustDisableValid) {
                return tsUserTrustDisable;
        }
        tsUserTrustDisable = false;

        Dictionary* dictionary = Dictionary::CreateDictionary(kSecTrustSettingsPrefsDomain, Dictionary::US_System);
        if (dictionary)
        {
                auto_ptr<Dictionary> prefsDict(dictionary);
                /* this returns false if the pref isn't there, just like we want */
                tsUserTrustDisable = prefsDict->getBoolValue(kSecTrustSettingsDisableUserTrustSettings);
        }

        tsUserTrustDisableValid = true;
        return tsUserTrustDisable;
}

#pragma mark --- TrustSettings global cache ---

/***
 *** cache submodule - keeps per-app copy of zero or one TrustSettings
 ***                               for each domain. Used only by SecTrustSettingsEvaluateCert()
 ***                               and SecTrustSettingsCopyQualifiedCerts(); results of
 ***                               manipulation by public API functions are not cached.
 ***/

/*
 * API/client code has to hold this lock when doing anything with any of
 * the TrustSettings maintained here.
 * It's recursive to accomodate CodeSigning's need to do cert verification
 * (while we evaluate app equivalence).
 */
static ModuleNexus<RecursiveMutex> sutCacheLock;

#define TRUST_SETTINGS_NUM_DOMAINS              3

/*
 * The three global TrustSettings.
 * We rely on the fact the the domain enums start with 0; we use
 * the domain value as an index into the following two arrays.
 */
static TrustSettings *globalTrustSettings[TRUST_SETTINGS_NUM_DOMAINS] =
                {NULL, NULL, NULL};

/*
 * Indicates "the associated global here is currently valid; if there isn't a
 * globalTrustSettings[domain], don't try to find one"
 */
static bool globalTrustSettingsValid[TRUST_SETTINGS_NUM_DOMAINS] =
                {false, false, false};

/* remember the fact that we've registered our KC callback */
static bool sutRegisteredCallback = false;

static void tsRegisterCallback();

/*
 * Assign global TrustSetting to new incoming value, which may be NULL.
 * Caller holds sutCacheLock.
 */
static void tsSetGlobalTrustSettings(
        TrustSettings *ts,
        SecTrustSettingsDomain domain)
{
        assert(((int)domain >= 0) && ((int)domain < TRUST_SETTINGS_NUM_DOMAINS));

        trustSettingsDbg("tsSetGlobalTrustSettings domain %d: caching TS %p old TS %p",
                (int)domain, ts, globalTrustSettings[domain]);
        delete globalTrustSettings[domain];
        globalTrustSettings[domain] = ts;
        globalTrustSettingsValid[domain] = ts ? true : false;
        tsRegisterCallback();
}

/*
 * Obtain global TrustSettings for specified domain if it exists.
 * Returns NULL if there is simply no TS for that domain.
 * The TS, if returned, belongs to this cache module.
 * Caller holds sutCacheLock.
 */
static TrustSettings *tsGetGlobalTrustSettings(
        SecTrustSettingsDomain domain)
{
        assert(((int)domain >= 0) && ((int)domain < TRUST_SETTINGS_NUM_DOMAINS));

        if((domain == kSecTrustSettingsDomainUser) && tsUserTrustSettingsDisabled()) {
                trustSettingsDbg("tsGetGlobalTrustSettings: skipping DISABLED user domain");
                return NULL;
        }

        if(globalTrustSettingsValid[domain]) {
                // ready or not, use this
                return globalTrustSettings[domain];
        }
        assert(globalTrustSettings[domain] == NULL);

        /* try to find one */
        OSStatus result = errSecSuccess;
        TrustSettings *ts = NULL;
        /* don't create; trim if found */
        result = TrustSettings::CreateTrustSettings(domain, CREATE_NO, TRIM_YES, ts);
    if (   (domain != kSecTrustSettingsDomainSystem)
        && (result == errSecInternalComponent)) {
        /*
         * Could not connect to ocspd to get the user/admin domain trust settings
         * This happens in single user mode for example.
         * Valid flag is set to false and continue.
         */
        trustSettingsDbg("tsGetGlobalTrustSettings: could not connect to ocspd for domain (%d)",(int)domain);
        globalTrustSettingsValid[domain] = false;
        tsRegisterCallback();
        return NULL;
    }
    else if (result == errSecNoTrustSettings) {
                /*
                 * No TrustSettings for this domain, actually a fairly common case.
                 * Optimize: don't bother trying this again.
                 */
                trustSettingsDbg("tsGetGlobalTrustSettings: flagging known NULL");
                globalTrustSettingsValid[domain] = true;
                tsRegisterCallback();
                return NULL;
        }
    else if(result != errSecSuccess) {
        /* gross error */
        MacOSError::throwMe(result);
    }

        tsSetGlobalTrustSettings(ts, domain);
        return ts;
}

/*
 * Purge TrustSettings cache.
 * Called by Keychain Event callback and by our API functions that
 * modify trust settings.
 * Caller can NOT hold sutCacheLock.
 */
static void tsPurgeCache()
{
        int domain;

        StLock<Mutex>   _(sutCacheLock());
        trustSettingsDbg("tsPurgeCache");
        for(domain=0; domain<TRUST_SETTINGS_NUM_DOMAINS; domain++) {
                tsSetGlobalTrustSettings(NULL, (SecTrustSettingsDomain) domain);
        }
}

/*
 * Keychain event callback function, for notification by other processes that
 * user trust list(s) has/have changed.
 */
static OSStatus tsTrustSettingsCallback (
   SecKeychainEvent keychainEvent,
   SecKeychainCallbackInfo *info,
   void *context)
{
        trustSettingsDbg("tsTrustSettingsCallback, event %d", (int)keychainEvent);
        if(keychainEvent != kSecTrustSettingsChangedEvent) {
                /* should not happen, right? */
                return errSecSuccess;
        }
        if(info->pid == getpid()) {
                /*
                 * Avoid dup cache invalidates: we already dealt with this event.
                 */
                trustSettingsDbg("cacheEventCallback: our pid, skipping");
        }
        else {
                tsPurgeCache();
        }
        return errSecSuccess;
}

/*
 * Ensure that we've registered for kSecTrustSettingsChangedEvent callbacks
 */
static void tsRegisterCallback()
{
        if(sutRegisteredCallback) {
                return;
        }
        trustSettingsDbg("tsRegisterCallback: registering callback");
        OSStatus ortn = SecKeychainAddCallback(tsTrustSettingsCallback,
                kSecTrustSettingsChangedEventMask, NULL);
        if(ortn) {
                trustSettingsDbg("tsRegisterCallback: SecKeychainAddCallback returned %d", (int)ortn);
                /* Not sure how this could ever happen - maybe if there is no run loop active? */
        }
        sutRegisteredCallback = true;
}

#pragma mark --- Static functions ---


/*
 * Called by API code when a trust list has changed; we notify other processes
 * and purge our own cache.
 */
static void tsTrustSettingsChanged()
{
        tsPurgeCache();

        /* The only interesting data is our pid */
        NameValueDictionary nvd;
        pid_t ourPid = getpid();
        nvd.Insert (new NameValuePair (PID_KEY,
                CssmData (reinterpret_cast<void*>(&ourPid), sizeof (pid_t))));
        CssmData data;
        nvd.Export (data);

        trustSettingsDbg("tsTrustSettingsChanged: posting notification");
        SecurityServer::ClientSession cs (Allocator::standard(), Allocator::standard());
        cs.postNotification (SecurityServer::kNotificationDomainDatabase,
                kSecTrustSettingsChangedEvent, data);
        free (data.data ());
}

/*
 * Common code for SecTrustSettingsCopyTrustSettings(),
 * SecTrustSettingsCopyModificationDate().
 */
static OSStatus tsCopyTrustSettings(
        SecCertificateRef cert,
        SecTrustSettingsDomain domain,
        CFArrayRef *trustSettings,              /* optionally RETURNED */
        CFDateRef *modDate)                             /* optionally RETURNED */
{
        BEGIN_RCSAPI

        TS_REQUIRED(cert)

        /* obtain fresh full copy from disk */
        OSStatus result;
        TrustSettings* ts;

        result = TrustSettings::CreateTrustSettings(domain, CREATE_NO, TRIM_NO, ts);

        // rather than throw these results, just return them because we are at the top level
        if (result == errSecNoTrustSettings) {
                return errSecItemNotFound;
        }
        else if (result != errSecSuccess) {
                return result;
        }

        auto_ptr<TrustSettings>_(ts); // make sure this gets deleted just in case something throws underneath

        if(trustSettings) {
                *trustSettings = ts->copyTrustSettings(cert);
        }
        if(modDate) {
                *modDate = ts->copyModDate(cert);
        }

        END_RCSAPI
}

static void tsAddConditionalCerts(CFMutableArrayRef certArray);

/*
 * Common code for SecTrustSettingsCopyQualifiedCerts() and
 * SecTrustSettingsCopyUnrestrictedRoots().
 */
static OSStatus tsCopyCertsCommon(
        /* usage constraints, all optional */
        const CSSM_OID                  *policyOID,
        const char                              *policyString,
        SecTrustSettingsKeyUsage keyUsage,
        /* constrain to only roots */
        bool                                    onlyRoots,
        /* per-domain enables */
        bool                                    user,
        bool                                    admin,
        bool                                    system,
        CFArrayRef                              *certArray)             /* RETURNED */
{
        StLock<Mutex> _TC(sutCacheLock());
        StLock<Mutex> _TK(SecTrustKeychainsGetMutex());

        TS_REQUIRED(certArray)

        /* this relies on the domain enums being numbered 0..2, user..system */
        bool domainEnable[3] = {user, admin, system};

        /* we'll retain it again before successful exit */
        CFRef<CFMutableArrayRef> outArray(CFArrayCreateMutable(NULL, 0,
                &kCFTypeArrayCallBacks));

        /*
         * Search all keychains - user's keychain list, System.keychain,
         * and system root store
         */
        StorageManager::KeychainList keychains;
        Keychain adminKc;
        if(user) {
                globals().storageManager.getSearchList(keychains);
        }
        if(user || admin) {
                adminKc = globals().storageManager.make(ADMIN_CERT_STORE_PATH, false);
                keychains.push_back(adminKc);
        }
        Keychain sysRootKc = globals().storageManager.make(SYSTEM_ROOT_STORE_PATH, false);
        keychains.push_back(sysRootKc);

        assert(kSecTrustSettingsDomainUser == 0);
        for(unsigned domain=0; domain<TRUST_SETTINGS_NUM_DOMAINS; domain++) {
                if(!domainEnable[domain]) {
                        continue;
                }
                TrustSettings *ts = tsGetGlobalTrustSettings((SecTrustSettingsDomain)domain);
                if(ts == NULL) {
                        continue;
                }
                ts->findQualifiedCerts(keychains,
                        false,          /* !findAll */
                        onlyRoots,
                        policyOID, policyString, keyUsage,
                        outArray);
        }
        if (system) {
                tsAddConditionalCerts(outArray);
        }
        *certArray = outArray;
        CFRetain(*certArray);
        trustSettingsDbg("tsCopyCertsCommon: %ld certs found",
                CFArrayGetCount(outArray));
        return errSecSuccess;
}

static void tsAddConditionalCerts(CFMutableArrayRef certArray)
{
#if TARGET_OS_MAC && !TARGET_IPHONE_SIMULATOR && !TARGET_OS_IPHONE && !TARGET_OS_NANO
        struct certmap_entry_s {
                CFStringRef bundleId;
                const UInt8* data;
                const CFIndex length;
        };
        typedef struct certmap_entry_s certmap_entry_t;

        CFBundleRef bundle = CFBundleGetMainBundle();
        CFStringRef bundleIdentifier = (bundle) ? CFBundleGetIdentifier(bundle) : NULL;
        if (!bundleIdentifier || !certArray) { return; }

        // conditionally include 1024-bit compatibility roots for specific apps
        const certmap_entry_t certmap[] = {
                { CFSTR("com.autodesk.AdSSO"), _GTECyberTrustGlobalRootCA, sizeof(_GTECyberTrustGlobalRootCA) }, // rdar://25916338
                { CFSTR("com.clo3d.MD5"), _ThawtePremiumServerCA, sizeof(_ThawtePremiumServerCA) }, // rdar://26281864
        };

        unsigned int i, certmaplen = sizeof(certmap) / sizeof(certmap_entry_t);
        for (i=0; i<certmaplen; i++) {
                if (CFStringCompare(bundleIdentifier, certmap[i].bundleId, 0) == kCFCompareEqualTo) {
                        SecCertificateRef cert = SecCertificateCreateWithBytes(NULL, certmap[i].data, certmap[i].length);
                        if (!cert) { continue; }
                        CFArrayAppendValue(certArray, cert);
                        CFRelease(cert);
                        cert = NULL;
                }
        }
#else
        // this function is a no-op on iOS platforms
#endif
}


#pragma mark --- SPI functions ---


/*
 * Fundamental routine used by TP to ascertain status of one cert.
 *
 * Returns true in *foundMatchingEntry if a trust setting matching
 * specific constraints was found for the cert. Returns true in
 * *foundAnyEntry if any entry was found for the cert, even if it
 * did not match the specified constraints. The TP uses this to
 * optimize for the case where a cert is being evaluated for
 * one type of usage, and then later for another type. If
 * foundAnyEntry is false, the second evaluation need not occur.
 *
 * Returns the domain in which a setting was found in *foundDomain.
 *
 * Allowed errors applying to the specified cert evaluation
 * are returned in a mallocd array in *allowedErrors and must
 * be freed by caller.
 *
 * The design of the entire TrustSettings module is centered around
 * optimizing the performance of this routine (security concerns
 * aside, that is). It's why the per-cert dictionaries are stored
 * as a dictionary, keyed off of the cert hash. It's why TrustSettings
 * are cached in memory by tsGetGlobalTrustSettings(), and why those
 * cached TrustSettings objects are 'trimmed' of dictionary fields
 * which are not needed to verify a cert.
 *
 * The API functions which are used to manipulate Trust Settings
 * are called infrequently and need not be particularly fast since
 * they result in user interaction for authentication. Thus they do
 * not use cached TrustSettings as this function does.
 */
OSStatus SecTrustSettingsEvaluateCert(
        CFStringRef                             certHashStr,
        /* parameters describing the current cert evalaution */
        const CSSM_OID                  *policyOID,
        const char                              *policyString,          /* optional */
        uint32                                  policyStringLen,
        SecTrustSettingsKeyUsage keyUsage,                      /* optional */
        bool                                    isRootCert,                     /* for checking default setting */
        /* RETURNED values */
        SecTrustSettingsDomain  *foundDomain,
        CSSM_RETURN                             **allowedErrors,        /* mallocd */
        uint32                                  *numAllowedErrors,
        SecTrustSettingsResult  *resultType,
        bool                                    *foundMatchingEntry,
        bool                                    *foundAnyEntry)
{
        BEGIN_RCSAPI

        StLock<Mutex>   _(sutCacheLock());

        TS_REQUIRED(certHashStr)
        TS_REQUIRED(foundDomain)
        TS_REQUIRED(allowedErrors)
        TS_REQUIRED(numAllowedErrors)
        TS_REQUIRED(resultType)
        TS_REQUIRED(foundMatchingEntry)
        TS_REQUIRED(foundAnyEntry)

        /* ensure a NULL_terminated string */
        auto_array<char> polStr;
        if(policyString != NULL && policyStringLen > 0) {
                polStr.allocate(policyStringLen + 1);
                memmove(polStr.get(), policyString, policyStringLen);
                if(policyString[policyStringLen - 1] != '\0') {
                        (polStr.get())[policyStringLen] = '\0';
                }
        }

        /* initial condition - this can grow if we inspect multiple TrustSettings */
        *allowedErrors = NULL;
        *numAllowedErrors = 0;

        /*
         * This loop relies on the ordering of the SecTrustSettingsDomain enum:
         * search user first, then admin, then system.
         */
        assert(kSecTrustSettingsDomainAdmin == (kSecTrustSettingsDomainUser + 1));
        assert(kSecTrustSettingsDomainSystem == (kSecTrustSettingsDomainAdmin + 1));
        bool foundAny = false;
        for(unsigned domain=kSecTrustSettingsDomainUser;
                             domain<=kSecTrustSettingsDomainSystem;
                                 domain++) {
                TrustSettings *ts = tsGetGlobalTrustSettings((SecTrustSettingsDomain)domain);
                if(ts == NULL) {
                        continue;
                }

                /* validate cert returns true if matching entry was found */
                bool foundAnyHere = false;
                bool found = ts->evaluateCert(certHashStr, policyOID,
                        polStr.get(), keyUsage, isRootCert,
                        allowedErrors, numAllowedErrors, resultType, &foundAnyHere);

                if(found) {
                        /*
                         * Note this, even though we may overwrite it later if this
                         * is an Unspecified entry and we find a definitive entry
                         * later
                         */
                        *foundDomain = (SecTrustSettingsDomain)domain;
                }
                if(found && (*resultType != kSecTrustSettingsResultUnspecified)) {
                        trustSettingsDbg("SecTrustSettingsEvaluateCert: found in domain %d", domain);
                        *foundAnyEntry = true;
                        *foundMatchingEntry = true;
                        return errSecSuccess;
                }
                foundAny |= foundAnyHere;
        }
        trustSettingsDbg("SecTrustSettingsEvaluateCert: NOT FOUND");
        *foundAnyEntry = foundAny;
        *foundMatchingEntry = false;
        return errSecSuccess;
        END_RCSAPI
}

/*
 * Obtain trusted certs which match specified usage.
 * Only certs with a SecTrustSettingsResult of
 * kSecTrustSettingsResultTrustRoot or
 * or kSecTrustSettingsResultTrustAsRoot will be returned.
 * To be used by SecureTransport for its SSLSetTrustedRoots() call;
 * I hope nothing else has to use this...
 * Caller must CFRelease the returned CFArrayRef.
 */
OSStatus SecTrustSettingsCopyQualifiedCerts(
        const CSSM_OID                          *policyOID,
        const char                                      *policyString,          /* optional */
        uint32                                          policyStringLen,
        SecTrustSettingsKeyUsage        keyUsage,                       /* optional */
        CFArrayRef                                      *certArray)                     /* RETURNED */
{
        BEGIN_RCSAPI

        /* ensure a NULL_terminated string */
        auto_array<char> polStr;
        if(policyString != NULL) {
                polStr.allocate(policyStringLen + 1);
                memmove(polStr.get(), policyString, policyStringLen);
                if(policyString[policyStringLen - 1] != '\0') {
                        (polStr.get())[policyStringLen] = '\0';
                }
        }

        return tsCopyCertsCommon(policyOID, polStr.get(), keyUsage,
                false,                          /* !onlyRoots */
                true, true, true,       /* all domains */
                certArray);

        END_RCSAPI
}

/*
 * Obtain unrestricted root certs from the specified domain(s).
 * Only returns roots with no usage constraints.
 * Caller must CFRelease the returned CFArrayRef.
 */
OSStatus SecTrustSettingsCopyUnrestrictedRoots(
        Boolean                                 user,
        Boolean                                 admin,
        Boolean                                 system,
        CFArrayRef                              *certArray)             /* RETURNED */
{
        BEGIN_RCSAPI

        OSStatus status = tsCopyCertsCommon(NULL, NULL, NULL,   /* no constraints */
                true,                           /* onlyRoots */
                user, admin, system,
                certArray);

    return status;

        END_RCSAPI
}

static const char hexChars[16] = {
        '0', '1', '2', '3', '4', '5', '6', '7',
        '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};

/*
 * Obtain a string representing a cert's SHA1 digest. This string is
 * the key used to look up per-cert trust settings in a TrustSettings record.
 */
CFStringRef SecTrustSettingsCertHashStrFromCert(
        SecCertificateRef certRef)
{
        if(certRef == NULL) {
                return NULL;
        }

        if(certRef == kSecTrustSettingsDefaultRootCertSetting) {
                /* use this string instead of the cert hash as the dictionary key */
                trustSettingsDbg("SecTrustSettingsCertHashStrFromCert: DefaultSetting");
        secerror("Caller passed kSecTrustSettingsDefaultRootCertSetting. This constant is deprecated and no longer affects the behavior of the system.");
                return kSecTrustRecordDefaultRootCert;
        }

        CSSM_DATA certData;
        OSStatus ortn = SecCertificateGetData(certRef, &certData);
        if(ortn) {
                return NULL;
        }
        return SecTrustSettingsCertHashStrFromData(certData.Data, certData.Length);
}

CFStringRef SecTrustSettingsCertHashStrFromData(
        const void *cert,
        size_t certLen)
{
        unsigned char digest[CC_SHA1_DIGEST_LENGTH];
        char asciiDigest[(2 * CC_SHA1_DIGEST_LENGTH) + 1];
        unsigned dex;
        char *outp = asciiDigest;
        unsigned char *inp = digest;

        if(cert == NULL) {
                return NULL;
        }

        CC_SHA1(cert, (CC_LONG)certLen, digest);

        for(dex=0; dex<CC_SHA1_DIGEST_LENGTH; dex++) {
                unsigned c = *inp++;
                outp[1] = hexChars[c & 0xf];
                c >>= 4;
                outp[0] = hexChars[c];
                outp += 2;
        }
        *outp = 0;
        return CFStringCreateWithCString(NULL, asciiDigest, kCFStringEncodingASCII);
}

/*
 * Add a cert's TrustSettings to a non-persistent TrustSettings record.
 * No locking or cache flushing here; it's all local to the TrustSettings
 * we construct here.
 */
OSStatus SecTrustSettingsSetTrustSettingsExternal(
        CFDataRef                       settingsIn,                                     /* optional */
        SecCertificateRef       certRef,                                        /* optional */
        CFTypeRef                       trustSettingsDictOrArray,       /* optional */
        CFDataRef                       *settingsOut)                           /* RETURNED */
{
        BEGIN_RCSAPI

        TS_REQUIRED(settingsOut)

        OSStatus result;
        TrustSettings* ts;

        result = TrustSettings::CreateTrustSettings((SecTrustSettingsDomain)kSecTrustSettingsDomainMemory, settingsIn, ts);
        if (result != errSecSuccess) {
                return result;
        }

        auto_ptr<TrustSettings>_(ts);

        if(certRef != NULL) {
                ts->setTrustSettings(certRef, trustSettingsDictOrArray);
        }
        *settingsOut = ts->createExternal();
        return errSecSuccess;

        END_RCSAPI
}

#pragma mark --- API functions ---

OSStatus SecTrustSettingsCopyTrustSettings(
        SecCertificateRef certRef,
        SecTrustSettingsDomain domain,
        CFArrayRef *trustSettings)                              /* RETURNED */
{
        TS_REQUIRED(certRef)
        TS_REQUIRED(trustSettings)

        OSStatus result = tsCopyTrustSettings(certRef, domain, trustSettings, NULL);
        if (result == errSecSuccess && *trustSettings == NULL) {
                result = errSecItemNotFound; /* documented result if no trust settings exist */
        }
        return result;
}

OSStatus SecTrustSettingsCopyModificationDate(
        SecCertificateRef               certRef,
        SecTrustSettingsDomain  domain,
        CFDateRef                               *modificationDate)      /* RETURNED */
{
        TS_REQUIRED(certRef)
        TS_REQUIRED(modificationDate)

        OSStatus result = tsCopyTrustSettings(certRef, domain, NULL, modificationDate);
        if (result == errSecSuccess && *modificationDate == NULL) {
                result = errSecItemNotFound; /* documented result if no trust settings exist */
        }
        return result;
}

/* works with existing and with new cert */
OSStatus SecTrustSettingsSetTrustSettings(
        SecCertificateRef certRef,
        SecTrustSettingsDomain domain,
        CFTypeRef trustSettingsDictOrArray)
{
        BEGIN_RCSAPI

        TS_REQUIRED(certRef)

        if(domain == kSecTrustSettingsDomainSystem) {
                return errSecDataNotModifiable;
        }

        OSStatus result;
        TrustSettings* ts;

        result = TrustSettings::CreateTrustSettings(domain, CREATE_YES, TRIM_NO, ts);
        if (result != errSecSuccess) {
                return result;
        }

        auto_ptr<TrustSettings>_(ts);

        ts->setTrustSettings(certRef, trustSettingsDictOrArray);
        ts->flushToDisk();
        tsTrustSettingsChanged();
        return errSecSuccess;

        END_RCSAPI
}

OSStatus SecTrustSettingsRemoveTrustSettings(
        SecCertificateRef cert,
        SecTrustSettingsDomain domain)
{
        BEGIN_RCSAPI

        TS_REQUIRED(cert)

        if(domain == kSecTrustSettingsDomainSystem) {
                return errSecDataNotModifiable;
        }

        OSStatus result;
        TrustSettings* ts;

        result = TrustSettings::CreateTrustSettings(domain, CREATE_NO, TRIM_NO, ts);
        if (result != errSecSuccess) {
                return result;
        }

        auto_ptr<TrustSettings>_(ts);

        /* deleteTrustSettings throws if record not found */
        trustSettingsDbg("SecTrustSettingsRemoveTrustSettings: deleting from domain %d",
                (int)domain);
        ts->deleteTrustSettings(cert);
        ts->flushToDisk();
        tsTrustSettingsChanged();
        return errSecSuccess;

        END_RCSAPI
}

/* get all certs listed in specified domain */
OSStatus SecTrustSettingsCopyCertificates(
        SecTrustSettingsDomain  domain,
        CFArrayRef                              *certArray)
{
        BEGIN_RCSAPI

        TS_REQUIRED(certArray)

        OSStatus result;
        TrustSettings* ts;

        result = TrustSettings::CreateTrustSettings(domain, CREATE_NO, TRIM_NO, ts);
        if (result != errSecSuccess) {
                return result;
        }

        auto_ptr<TrustSettings>_(ts);

        CFMutableArrayRef outArray = CFArrayCreateMutable(NULL, 0, &kCFTypeArrayCallBacks);

        /*
         * Keychains to search: user's search list, System.keychain, system root store
         */
        StorageManager::KeychainList keychains;
        Keychain adminKc;
        Keychain sysRootKc;
        switch(domain) {
                case kSecTrustSettingsDomainUser:
                        /* user search list */
                        globals().storageManager.getSearchList(keychains);
                        /* drop thru to next case */
                case kSecTrustSettingsDomainAdmin:
                        /* admin certs in system keychain */
                        adminKc = globals().storageManager.make(ADMIN_CERT_STORE_PATH, false);
                        keychains.push_back(adminKc);
                        /* drop thru to next case */
                case kSecTrustSettingsDomainSystem:
                        /* and, for all cases, immutable system root store */
                        sysRootKc = globals().storageManager.make(SYSTEM_ROOT_STORE_PATH, false);
                        keychains.push_back(sysRootKc);
                default:
                        /* already validated when we created the TrustSettings */
                        break;
        }
        ts->findCerts(keychains, outArray);
        if(CFArrayGetCount(outArray) == 0) {
                CFRelease(outArray);
                return errSecNoTrustSettings;
        }
        if (kSecTrustSettingsDomainSystem == domain) {
                tsAddConditionalCerts(outArray);
        }
        *certArray = outArray;
        END_RCSAPI
}

static CFArrayRef gUserAdminCerts = NULL;
static bool gUserAdminCertsCacheBuilt = false;
static ReadWriteLock gUserAdminCertsLock;

void SecTrustSettingsPurgeUserAdminCertsCache(void) {
    StReadWriteLock _(gUserAdminCertsLock, StReadWriteLock::Write);
    CFReleaseNull(gUserAdminCerts);
    gUserAdminCertsCacheBuilt = false;
}

OSStatus SecTrustSettingsCopyCertificatesForUserAdminDomains(
                                                             CFArrayRef  *certArray)
{
    TS_REQUIRED(certArray);
    OSStatus result = errSecSuccess;

    { /* Hold the read lock for the check */
        StReadWriteLock _(gUserAdminCertsLock, StReadWriteLock::Read);
        if (gUserAdminCertsCacheBuilt) {
            if (gUserAdminCerts) {
                *certArray = (CFArrayRef)CFRetain(gUserAdminCerts);
                return errSecSuccess;
            } else {
                return errSecNoTrustSettings;
            }
        }
    }

    /* There were no cached results. We'll have to recreate them. */
    CFMutableArrayRef outArray = CFArrayCreateMutable(NULL, 0, &kCFTypeArrayCallBacks);
    if (!outArray) {
        return errSecAllocate;
    }

    CFArrayRef userTrusted = NULL, adminTrusted = NULL;
    OSStatus userStatus = SecTrustSettingsCopyCertificates(kSecTrustSettingsDomainUser, &userTrusted);
    if ((userStatus == errSecSuccess) && (userTrusted != NULL)) {
        CFArrayAppendArray(outArray, userTrusted, CFRangeMake(0, CFArrayGetCount(userTrusted)));
        CFRelease(userTrusted);
    }

    OSStatus adminStatus = SecTrustSettingsCopyCertificates(kSecTrustSettingsDomainAdmin, &adminTrusted);
    if ((adminStatus == errSecSuccess) && (adminTrusted != NULL)) {
        CFArrayAppendArray(outArray, adminTrusted, CFRangeMake(0, CFArrayGetCount(adminTrusted)));
        CFRelease(adminTrusted);
    }

    /* Lack of trust settings for a domain results in an error above. Only fail
     * if we weren't able to get trust settings for both domains. */
    if (userStatus != errSecSuccess && adminStatus != errSecSuccess) {
        result = userStatus;
    }

    if (result != errSecSuccess && outArray) {
        CFRelease(outArray);
        outArray = NULL;
    }

    *certArray = outArray;

    /* For valid results, update the global cache */
    if (result == errSecSuccess || result == errSecNoTrustSettings) {
        StReadWriteLock _(gUserAdminCertsLock, StReadWriteLock::Write);
        CFReleaseNull(gUserAdminCerts);
        gUserAdminCerts = (CFArrayRef)CFRetainSafe(outArray);
        gUserAdminCertsCacheBuilt = true;
    }

    return result;
}

/*
 * Obtain an external, portable representation of the specified
 * domain's TrustSettings. Caller must CFRelease the returned data.
 */
OSStatus SecTrustSettingsCreateExternalRepresentation(
        SecTrustSettingsDomain  domain,
        CFDataRef                               *trustSettings)
{
        BEGIN_RCSAPI

        TS_REQUIRED(trustSettings)

        OSStatus result;
        TrustSettings* ts;

        result = TrustSettings::CreateTrustSettings(domain, CREATE_NO, TRIM_NO, ts);
        if (result != errSecSuccess) {
                return result;
        }

        auto_ptr<TrustSettings>_(ts);

        *trustSettings = ts->createExternal();
        return errSecSuccess;

        END_RCSAPI
}

/*
 * Import trust settings, obtained via SecTrustSettingsCreateExternalRepresentation,
 * into the specified domain.
 */
OSStatus SecTrustSettingsImportExternalRepresentation(
        SecTrustSettingsDomain  domain,
        CFDataRef                               trustSettings)          /* optional - NULL means empty settings */
{
        BEGIN_RCSAPI

        if(domain == kSecTrustSettingsDomainSystem) {
                return errSecDataNotModifiable;
        }

        OSStatus result;
        TrustSettings* ts;

        result = TrustSettings::CreateTrustSettings(domain, trustSettings, ts);
        if (result != errSecSuccess) {
                return result;
        }

        auto_ptr<TrustSettings>_(ts);

        ts->flushToDisk();
        tsTrustSettingsChanged();
        return errSecSuccess;

        END_RCSAPI
}