[apple/libsecurity_codesigning.git] / lib / StaticCode.cpp

/*
 * Copyright (c) 2006-2007 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
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 * 
 * @APPLE_LICENSE_HEADER_END@
 */

//
// StaticCode - SecStaticCode API objects
//
#include "StaticCode.h"
#include "Code.h"
#include "reqmaker.h"
#include "reqdumper.h"
#include "sigblob.h"
#include "resources.h"
#include "renum.h"
#include "detachedrep.h"
#include "csdatabase.h"
#include "csutilities.h"
#include <CoreFoundation/CFURLAccess.h>
#include <Security/SecPolicyPriv.h>
#include <Security/SecTrustPriv.h>
#include <Security/SecCertificatePriv.h>
#include <Security/CMSPrivate.h>
#include <Security/SecCmsContentInfo.h>
#include <Security/SecCmsSignerInfo.h>
#include <Security/SecCmsSignedData.h>
#include <security_utilities/unix++.h>
#include <security_utilities/cfmunge.h>
#include <Security/CMSDecoder.h>


namespace Security {
namespace CodeSigning {

using namespace UnixPlusPlus;


//
// Construct a SecStaticCode object given a disk representation object
//
SecStaticCode::SecStaticCode(DiskRep *rep)
        : mRep(rep),
          mValidated(false), mExecutableValidated(false),
          mDesignatedReq(NULL), mGotResourceBase(false), mEvalDetails(NULL)
{
        CODESIGN_STATIC_CREATE(this, rep);
        checkForSystemSignature();
}


//
// Clean up a SecStaticCode object
//
SecStaticCode::~SecStaticCode() throw()
{
        ::free(const_cast<Requirement *>(mDesignatedReq));
}


//
// CF-level comparison of SecStaticCode objects compares CodeDirectory hashes if signed,
// and falls back on comparing canonical paths if (both are) not.
//
bool SecStaticCode::equal(SecCFObject &secOther)
{
        SecStaticCode *other = static_cast<SecStaticCode *>(&secOther);
        CFDataRef mine = this->cdHash();
        CFDataRef his = other->cdHash();
        if (mine || his)
                return mine && his && CFEqual(mine, his);
        else
                return CFEqual(this->canonicalPath(), other->canonicalPath());
}

CFHashCode SecStaticCode::hash()
{
        if (CFDataRef h = this->cdHash())
                return CFHash(h);
        else
                return CFHash(this->canonicalPath());
}


//
// Attach a detached signature.
//
void SecStaticCode::detachedSignature(CFDataRef sigData)
{
        if (sigData) {
                mRep = new DetachedRep(sigData, mRep->base(), "explicit detached");
                CODESIGN_STATIC_ATTACH_EXPLICIT(this, mRep);
        } else {
                mRep = mRep->base();
                CODESIGN_STATIC_ATTACH_EXPLICIT(this, NULL);
        }
}


//
// Consult the system detached signature database to see if it contains
// a detached signature for this StaticCode. If it does, fetch and attach it.
// We do this only if the code has no signature already attached.
//
void SecStaticCode::checkForSystemSignature()
{
        if (!this->isSigned())
                try {
                        if (RefPointer<DiskRep> dsig = signatureDatabase().findCode(mRep)) {
                                CODESIGN_STATIC_ATTACH_SYSTEM(this, dsig);
                                mRep = dsig;
                        }
                } catch (...) {
                }
}


//
// Return a descriptive string identifying the source of the code signature
//
string SecStaticCode::signatureSource()
{
        if (!isSigned())
                return "unsigned";
        if (DetachedRep *rep = dynamic_cast<DetachedRep *>(mRep.get()))
                return rep->source();
        return "embedded";
}


//
// Do ::required, but convert incoming SecCodeRefs to their SecStaticCodeRefs
// (if possible).
//
SecStaticCode *SecStaticCode::requiredStatic(SecStaticCodeRef ref)
{
        SecCFObject *object = SecCFObject::required(ref, errSecCSInvalidObjectRef);
        if (SecStaticCode *scode = dynamic_cast<SecStaticCode *>(object))
                return scode;
        else if (SecCode *code = dynamic_cast<SecCode *>(object))
                return code->staticCode();
        else    // neither (a SecSomethingElse)
                MacOSError::throwMe(errSecCSInvalidObjectRef);
}

SecCode *SecStaticCode::optionalDynamic(SecStaticCodeRef ref)
{
        SecCFObject *object = SecCFObject::required(ref, errSecCSInvalidObjectRef);
        if (dynamic_cast<SecStaticCode *>(object))
                return NULL;
        else if (SecCode *code = dynamic_cast<SecCode *>(object))
                return code;
        else    // neither (a SecSomethingElse)
                MacOSError::throwMe(errSecCSInvalidObjectRef);
}


//
// Void all cached validity data.
//
// We also throw out cached components, because the new signature data may have
// a different idea of what components should be present. We could reconcile the
// cached data instead, if performance seems to be impacted.
//
void SecStaticCode::resetValidity()
{
        CODESIGN_EVAL_STATIC_RESET(this);
        mValidated = false;
        mExecutableValidated = false;
        mDir = NULL;
        mSignature = NULL;
        for (unsigned n = 0; n < cdSlotCount; n++)
                mCache[n] = NULL;
        mInfoDict = NULL;
        mEntitlements = NULL;
        mResourceDict = NULL;
        mDesignatedReq = NULL;
        mGotResourceBase = false;
        mTrust = NULL;
        mCertChain = NULL;
        mEvalDetails = NULL;
        mRep->flush();
        
        // we may just have updated the system database, so check again
        checkForSystemSignature();
}


//
// Retrieve a sealed component by special slot index.
// If the CodeDirectory has already been validated, validate against that.
// Otherwise, retrieve the component without validation (but cache it). Validation
// will go through the cache and validate all cached components.
//
CFDataRef SecStaticCode::component(CodeDirectory::SpecialSlot slot)
{
        assert(slot <= cdSlotMax);
        
        CFRef<CFDataRef> &cache = mCache[slot];
        if (!cache) {
                if (CFRef<CFDataRef> data = mRep->component(slot)) {
                        if (validated()) // if the directory has been validated...
                                if (!codeDirectory()->validateSlot(CFDataGetBytePtr(data), // ... and it's no good
                                                CFDataGetLength(data), -slot))
                                        MacOSError::throwMe(errSecCSSignatureFailed); // ... then bail
                        cache = data;   // it's okay, cache it
                } else {        // absent, mark so
                        if (validated())        // if directory has been validated...
                                if (codeDirectory()->slotIsPresent(-slot)) // ... and the slot is NOT missing
                                        MacOSError::throwMe(errSecCSSignatureFailed);   // was supposed to be there
                        cache = CFDataRef(kCFNull);             // white lie
                }
        }
        return (cache == CFDataRef(kCFNull)) ? NULL : cache.get();
}


//
// Get the CodeDirectory.
// Throws (if check==true) or returns NULL (check==false) if there is none.
// Always throws if the CodeDirectory exists but is invalid.
// NEVER validates against the signature.
//
const CodeDirectory *SecStaticCode::codeDirectory(bool check /* = true */)
{
        if (!mDir) {
                if (mDir.take(mRep->codeDirectory())) {
                        const CodeDirectory *dir = reinterpret_cast<const CodeDirectory *>(CFDataGetBytePtr(mDir));
                        dir->checkIntegrity();
                }
        }
        if (mDir)
                return reinterpret_cast<const CodeDirectory *>(CFDataGetBytePtr(mDir));
        if (check)
                MacOSError::throwMe(errSecCSUnsigned);
        return NULL;
}


//
// Get the hash of the CodeDirectory.
// Returns NULL if there is none.
//
CFDataRef SecStaticCode::cdHash()
{
        if (!mCDHash) {
                if (const CodeDirectory *cd = codeDirectory(false)) {
                        SHA1 hash;
                        hash(cd, cd->length());
                        SHA1::Digest digest;
                        hash.finish(digest);
                        mCDHash.take(makeCFData(digest, sizeof(digest)));
                        CODESIGN_STATIC_CDHASH(this, digest, sizeof(digest));
                }
        }
        return mCDHash;
}


//
// Return the CMS signature blob; NULL if none found.
//
CFDataRef SecStaticCode::signature()
{
        if (!mSignature)
                mSignature.take(mRep->signature());
        if (mSignature)
                return mSignature;
        MacOSError::throwMe(errSecCSUnsigned);
}


//
// Verify the signature on the CodeDirectory.
// If this succeeds (doesn't throw), the CodeDirectory is statically trustworthy.
// Any outcome (successful or not) is cached for the lifetime of the StaticCode.
//
void SecStaticCode::validateDirectory()
{
        // echo previous outcome, if any
        if (!validated())
                try {
                        // perform validation (or die trying)
                        CODESIGN_EVAL_STATIC_DIRECTORY(this);
                        mValidationExpired = verifySignature();
                        component(cdInfoSlot);          // force load of Info Dictionary (if any)
                        CodeDirectory::SpecialSlot slot = codeDirectory()->nSpecialSlots;
                        if (slot > cdSlotMax)   // might have more special slots than we know about...
                                slot = cdSlotMax;       // ... but only process the ones we understand
                        for ( ; slot >= 1; --slot)
                                if (mCache[slot])       // if we already loaded that resource...
                                        validateComponent(slot); // ... then check it now
                        mValidated = true;                      // we've done the deed...
                        mValidationResult = noErr;      // ... and it was good
                } catch (const CommonError &err) {
                        mValidated = true;
                        mValidationResult = err.osStatus();
                        throw;
                } catch (...) {
                        secdebug("staticCode", "%p validation threw non-common exception", this);
                        mValidated = true;
                        mValidationResult = errSecCSInternalError;
                        throw;
                }
        assert(validated());
        if (mValidationResult == noErr) {
                if (mValidationExpired)
                        if ((apiFlags() & kSecCSConsiderExpiration)
                                        || (codeDirectory()->flags & kSecCodeSignatureForceExpiration))
                                MacOSError::throwMe(CSSMERR_TP_CERT_EXPIRED);
        } else
                MacOSError::throwMe(mValidationResult);
}


//
// Get the (signed) signing date from the code signature.
// Sadly, we need to validate the signature to get the date (as a side benefit).
// This means that you can't get the signing time for invalidly signed code.
//
// We could run the decoder "almost to" verification to avoid this, but there seems
// little practical point to such a duplication of effort.
//
CFAbsoluteTime SecStaticCode::signingTime()
{
        validateDirectory();
        return mSigningTime;
}


//
// Verify the CMS signature on the CodeDirectory.
// This performs the cryptographic tango. It returns if the signature is valid,
// or throws if it is not. As a side effect, a successful return sets up the
// cached certificate chain for future use.
// Returns true if the signature is expired (the X.509 sense), false if it's not.
//
bool SecStaticCode::verifySignature()
{
        // ad-hoc signed code is considered validly signed by definition
        if (flag(kSecCodeSignatureAdhoc)) {
                CODESIGN_EVAL_STATIC_SIGNATURE_ADHOC(this);
                return false;
        }
        
        DTRACK(CODESIGN_EVAL_STATIC_SIGNATURE, this, (char*)this->mainExecutablePath().c_str());

        // decode CMS and extract SecTrust for verification
        CFRef<CMSDecoderRef> cms;
        MacOSError::check(CMSDecoderCreate(&cms.aref())); // create decoder
        CFDataRef sig = this->signature();
        MacOSError::check(CMSDecoderUpdateMessage(cms, CFDataGetBytePtr(sig), CFDataGetLength(sig)));
        this->codeDirectory();  // load CodeDirectory (sets mDir)
        MacOSError::check(CMSDecoderSetDetachedContent(cms, mDir));
        MacOSError::check(CMSDecoderFinalizeMessage(cms));
        MacOSError::check(CMSDecoderSetSearchKeychain(cms, cfEmptyArray()));
    CMSSignerStatus status;
    MacOSError::check(CMSDecoderCopySignerStatus(cms, 0, verificationPolicy(),
                false, &status, &mTrust.aref(), NULL));
        if (status != kCMSSignerValid)
                MacOSError::throwMe(errSecCSSignatureFailed);
        
        // get signing date (we've got the decoder handle right here)
        mSigningTime = 0;               // "not present" marker (nobody could code sign on Jan 1, 2001 :-)
        SecCmsMessageRef cmsg;
        MacOSError::check(CMSDecoderGetCmsMessage(cms, &cmsg));
        SecCmsSignedDataRef signedData = NULL;
    int numContentInfos = SecCmsMessageContentLevelCount(cmsg);
    for(int dex = 0; !signedData && dex < numContentInfos; dex++) {
        SecCmsContentInfoRef ci = SecCmsMessageContentLevel(cmsg, dex);
        SECOidTag tag = SecCmsContentInfoGetContentTypeTag(ci);
        switch(tag) {
            case SEC_OID_PKCS7_SIGNED_DATA:
                                if (SecCmsSignedDataRef signedData = SecCmsSignedDataRef(SecCmsContentInfoGetContent(ci)))
                                        if (SecCmsSignerInfoRef signerInfo = SecCmsSignedDataGetSignerInfo(signedData, 0))
                                                SecCmsSignerInfoGetSigningTime(signerInfo, &mSigningTime);
                break;
            default:
                break;
        }
    }

        // set up the environment for SecTrust
        MacOSError::check(SecTrustSetAnchorCertificates(mTrust, cfEmptyArray())); // no anchors
        CSSM_APPLE_TP_ACTION_DATA actionData = {
                CSSM_APPLE_TP_ACTION_VERSION,   // version of data structure
                CSSM_TP_ACTION_IMPLICIT_ANCHORS // action flags
        };
        
        for (;;) {      // at most twice
                MacOSError::check(SecTrustSetParameters(mTrust,
                        CSSM_TP_ACTION_DEFAULT, CFTempData(&actionData, sizeof(actionData))));
        
                // evaluate trust and extract results
                SecTrustResultType trustResult;
                MacOSError::check(SecTrustEvaluate(mTrust, &trustResult));
                MacOSError::check(SecTrustGetResult(mTrust, &trustResult, &mCertChain.aref(), &mEvalDetails));
                CODESIGN_EVAL_STATIC_SIGNATURE_RESULT(this, trustResult, mCertChain ? CFArrayGetCount(mCertChain) : 0);
                switch (trustResult) {
                case kSecTrustResultProceed:
                case kSecTrustResultConfirm:
                case kSecTrustResultUnspecified:
                        break;                          // success
                case kSecTrustResultDeny:
                        MacOSError::throwMe(CSSMERR_APPLETP_TRUST_SETTING_DENY);        // user reject
                case kSecTrustResultInvalid:
                        assert(false);          // should never happen
                        MacOSError::throwMe(CSSMERR_TP_NOT_TRUSTED);
                case kSecTrustResultRecoverableTrustFailure:
                case kSecTrustResultFatalTrustFailure:
                case kSecTrustResultOtherError:
                        {
                                OSStatus result;
                                MacOSError::check(SecTrustGetCssmResultCode(mTrust, &result));
                                if (result == CSSMERR_TP_CERT_EXPIRED && !(actionData.ActionFlags & CSSM_TP_ACTION_ALLOW_EXPIRED)) {
                                        CODESIGN_EVAL_STATIC_SIGNATURE_EXPIRED(this);
                                        actionData.ActionFlags |= CSSM_TP_ACTION_ALLOW_EXPIRED;
                                        continue;               // retry validation
                                }
                                MacOSError::throwMe(result);
                        }
                }
                return actionData.ActionFlags & CSSM_TP_ACTION_ALLOW_EXPIRED;
        }
}


//
// Return the TP policy used for signature verification.
// This policy object is cached and reused.
//
SecPolicyRef SecStaticCode::verificationPolicy()
{
        if (!mPolicy)
                MacOSError::check(SecPolicyCopy(CSSM_CERT_X_509v3,
                        &CSSMOID_APPLE_TP_CODE_SIGNING, &mPolicy.aref()));
        return mPolicy;
}


//
// Validate a particular sealed, cached resource against its (special) CodeDirectory slot.
// The resource must already have been placed in the cache.
// This does NOT perform basic validation.
//
void SecStaticCode::validateComponent(CodeDirectory::SpecialSlot slot)
{
        assert(slot <= cdSlotMax);
        CFDataRef data = mCache[slot];
        assert(data);           // must be cached
        if (data == CFDataRef(kCFNull)) {
                if (codeDirectory()->slotIsPresent(-slot)) // was supposed to be there...
                                MacOSError::throwMe(errSecCSSignatureFailed);   // ... and is missing
        } else {
                if (!codeDirectory()->validateSlot(CFDataGetBytePtr(data), CFDataGetLength(data), -slot))
                        MacOSError::throwMe(errSecCSSignatureFailed);
        }
}


//
// Perform static validation of the main executable.
// This reads the main executable from disk and validates it against the
// CodeDirectory code slot array.
// Note that this is NOT an in-memory validation, and is thus potentially
// subject to timing attacks.
//
void SecStaticCode::validateExecutable()
{
        DTRACK(CODESIGN_EVAL_STATIC_EXECUTABLE, this,
                (char*)this->mainExecutablePath().c_str(), codeDirectory()->nCodeSlots);
        const CodeDirectory *cd = this->codeDirectory();
        if (!cd)
                MacOSError::throwMe(errSecCSUnsigned);
        AutoFileDesc fd(mainExecutablePath(), O_RDONLY);
        fd.fcntl(F_NOCACHE, true);              // turn off page caching (one-pass)
        if (Universal *fat = mRep->mainExecutableImage())
                fd.seek(fat->archOffset());
        size_t pageSize = cd->pageSize ? (1 << cd->pageSize) : 0;
        size_t remaining = cd->codeLimit;
        for (size_t slot = 0; slot < cd->nCodeSlots; ++slot) {
                size_t size = min(remaining, pageSize);
                if (!cd->validateSlot(fd, size, slot)) {
                        CODESIGN_EVAL_STATIC_EXECUTABLE_FAIL(this, slot);
                        mExecutableValidated = true;    // we tried
                        mExecutableValid = false;               // it failed
                        MacOSError::throwMe(errSecCSSignatureFailed);
                }
                remaining -= size;
        }
        mExecutableValidated = true;    // we tried
        mExecutableValid = true;                // it worked
}


//
// Perform static validation of sealed resources.
//
// This performs a whole-code static resource scan and effectively
// computes a concordance between what's on disk and what's in the ResourceDirectory.
// Any unsanctioned difference causes an error.
//
void SecStaticCode::validateResources()
{
        // sanity first
        CFDictionaryRef sealedResources = resourceDictionary();
        if (this->resourceBase())               // disk has resources
                if (sealedResources)
                        /* go to work below */;
                else
                        MacOSError::throwMe(errSecCSResourcesNotFound);
        else                                                    // disk has no resources
                if (sealedResources)
                        MacOSError::throwMe(errSecCSResourcesNotFound);
                else
                        return;                                 // no resources, not sealed - fine (no work)

        // found resources, and they are sealed
        CFDictionaryRef rules = cfget<CFDictionaryRef>(sealedResources, "rules");
        CFDictionaryRef files = cfget<CFDictionaryRef>(sealedResources, "files");
        DTRACK(CODESIGN_EVAL_STATIC_RESOURCES, this,
                (char*)this->mainExecutablePath().c_str(), int(CFDictionaryGetCount(files)));

        // make a shallow copy of the ResourceDirectory so we can "check off" what we find
        CFRef<CFMutableDictionaryRef> resourceMap = makeCFMutableDictionary(files);

        // scan through the resources on disk, checking each against the resourceDirectory
        CollectingContext ctx(*this);           // collect all failures in here
        ResourceBuilder resources(cfString(this->resourceBase()), rules);
        mRep->adjustResources(resources);
        string path;
        ResourceBuilder::Rule *rule;

        while (resources.next(path, rule)) {
                validateResource(path, ctx);
                CFDictionaryRemoveValue(resourceMap, CFTempString(path));
        }
        
        if (CFDictionaryGetCount(resourceMap) > 0) {
                secdebug("staticCode", "%p sealed resource(s) not found in code", this);
                CFDictionaryApplyFunction(resourceMap, SecStaticCode::checkOptionalResource, &ctx);
        }
        
        // now check for any errors found in the reporting context
        if (ctx)
                ctx.throwMe();
}


void SecStaticCode::checkOptionalResource(CFTypeRef key, CFTypeRef value, void *context)
{
        CollectingContext *ctx = static_cast<CollectingContext *>(context);
        ResourceSeal seal(value);
        if (!seal.optional())
                if (key && CFGetTypeID(key) == CFStringGetTypeID()) {
                        ctx->reportProblem(errSecCSBadResource, kSecCFErrorResourceMissing,
                                CFTempURL(CFStringRef(key), false, ctx->code.resourceBase()));
                } else
                        ctx->reportProblem(errSecCSBadResource, kSecCFErrorResourceSeal, key);
}


//
// Load, validate, cache, and return CFDictionary forms of sealed resources.
//
CFDictionaryRef SecStaticCode::infoDictionary()
{
        if (!mInfoDict) {
                mInfoDict.take(getDictionary(cdInfoSlot));
                secdebug("staticCode", "%p loaded InfoDict %p", this, mInfoDict.get());
        }
        return mInfoDict;
}

CFDictionaryRef SecStaticCode::entitlements()
{
        if (!mEntitlements) {
                validateDirectory();
                if (CFDataRef entitlementData = component(cdEntitlementSlot)) {
                        validateComponent(cdEntitlementSlot);
                        const EntitlementBlob *blob = reinterpret_cast<const EntitlementBlob *>(CFDataGetBytePtr(entitlementData));
                        if (blob->validateBlob()) {
                                mEntitlements.take(blob->entitlements());
                                secdebug("staticCode", "%p loaded Entitlements %p", this, mEntitlements.get());
                        }
                        // we do not consider a different blob type to be an error. We think it's a new format we don't understand
                }
        }
        return mEntitlements;
}

CFDictionaryRef SecStaticCode::resourceDictionary()
{
        if (mResourceDict)      // cached
                return mResourceDict;
        if (CFRef<CFDictionaryRef> dict = getDictionary(cdResourceDirSlot))
                if (cfscan(dict, "{rules=%Dn,files=%Dn}")) {
                        secdebug("staticCode", "%p loaded ResourceDict %p",
                                this, mResourceDict.get());
                        return mResourceDict = dict;
                }
        // bad format
        return NULL;
}


//
// Load and cache the resource directory base.
// Note that the base is optional for each DiskRep.
//
CFURLRef SecStaticCode::resourceBase()
{
        if (!mGotResourceBase) {
                string base = mRep->resourcesRootPath();
                if (!base.empty())
                        mResourceBase.take(makeCFURL(base, true));
                mGotResourceBase = true;
        }
        return mResourceBase;
}


//
// Load a component, validate it, convert it to a CFDictionary, and return that.
// This will force load and validation, which means that it will perform basic
// validation if it hasn't been done yet.
//
CFDictionaryRef SecStaticCode::getDictionary(CodeDirectory::SpecialSlot slot)
{
        validateDirectory();
        if (CFDataRef infoData = component(slot)) {
                validateComponent(slot);
                if (CFDictionaryRef dict = makeCFDictionaryFrom(infoData))
                        return dict;
                else
                        MacOSError::throwMe(errSecCSBadDictionaryFormat);
        }
        return NULL;
}


//
// Load, validate, and return a sealed resource.
// The resource data (loaded in to memory as a blob) is returned and becomes
// the responsibility of the caller; it is NOT cached by SecStaticCode.
//
// A resource that is not sealed will not be returned, and an error will be thrown.
// A missing resource will cause an error unless it's marked optional in the Directory.
// Under no circumstances will a corrupt resource be returned.
// NULL will only be returned for a resource that is neither sealed nor present
// (or that is sealed, absent, and marked optional).
// If the ResourceDictionary itself is not sealed, this function will always fail.
//
// There is currently no interface for partial retrieval of the resource data.
// (Since the ResourceDirectory does not currently support segmentation, all the
// data would have to be read anyway, but it could be read into a reusable buffer.)
//
CFDataRef SecStaticCode::resource(string path, ValidationContext &ctx)
{
        if (CFDictionaryRef rdict = resourceDictionary()) {
                if (CFTypeRef file = cfget(rdict, "files.%s", path.c_str())) {
                        ResourceSeal seal = file;
                        if (!resourceBase())    // no resources in DiskRep
                                MacOSError::throwMe(errSecCSResourcesNotFound);
                        CFRef<CFURLRef> fullpath = makeCFURL(path, false, resourceBase());
                        if (CFRef<CFDataRef> data = cfLoadFile(fullpath)) {
                                SHA1 hasher;
                                hasher(CFDataGetBytePtr(data), CFDataGetLength(data));
                                if (hasher.verify(seal.hash()))
                                        return data.yield();    // good
                                else
                                        ctx.reportProblem(errSecCSBadResource, kSecCFErrorResourceAltered, fullpath); // altered
                        } else {
                                if (!seal.optional())
                                        ctx.reportProblem(errSecCSBadResource, kSecCFErrorResourceMissing, fullpath); // was sealed but is now missing
                                else
                                        return NULL;    // validly missing
                        }
                } else
                        ctx.reportProblem(errSecCSBadResource, kSecCFErrorResourceAdded, CFTempURL(path, false, resourceBase()));
                return NULL;
        } else
                MacOSError::throwMe(errSecCSResourcesNotSealed);
}

CFDataRef SecStaticCode::resource(string path)
{
        ValidationContext ctx;
        return resource(path, ctx);
}


void SecStaticCode::validateResource(string path, ValidationContext &ctx)
{
        if (CFDictionaryRef rdict = resourceDictionary()) {
                if (CFTypeRef file = cfget(rdict, "files.%s", path.c_str())) {
                        ResourceSeal seal = file;
                        if (!resourceBase())    // no resources in DiskRep
                                MacOSError::throwMe(errSecCSResourcesNotFound);
                        CFRef<CFURLRef> fullpath = makeCFURL(path, false, resourceBase());
                        AutoFileDesc fd(cfString(fullpath), O_RDONLY, FileDesc::modeMissingOk); // open optional filee
                        if (fd) {
                                SHA1 hasher;
                                hashFileData(fd, hasher);
                                if (hasher.verify(seal.hash()))
                                        return;                 // verify good
                                else
                                        ctx.reportProblem(errSecCSBadResource, kSecCFErrorResourceAltered, fullpath); // altered
                        } else {
                                if (!seal.optional())
                                        ctx.reportProblem(errSecCSBadResource, kSecCFErrorResourceMissing, fullpath); // was sealed but is now missing
                                else
                                        return;                 // validly missing
                        }
                } else
                        ctx.reportProblem(errSecCSBadResource, kSecCFErrorResourceAdded, CFTempURL(path, false, resourceBase()));
        } else
                MacOSError::throwMe(errSecCSResourcesNotSealed);
}


//
// Test a CodeDirectory flag.
// Returns false if there is no CodeDirectory.
// May throw if the CodeDirectory is present but somehow invalid.
//
bool SecStaticCode::flag(uint32_t tested)
{
        if (const CodeDirectory *cd = this->codeDirectory(false))
                return cd->flags & tested;
        else
                return false;
}


//
// Retrieve the full SuperBlob containing all internal requirements.
//
const Requirements *SecStaticCode::internalRequirements()
{
        if (CFDataRef req = component(cdRequirementsSlot))
                return (const Requirements *)CFDataGetBytePtr(req);
        else
                return NULL;
}


//
// Retrieve a particular internal requirement by type.
//
const Requirement *SecStaticCode::internalRequirement(SecRequirementType type)
{
        if (const Requirements *reqs = internalRequirements())
                return reqs->find<Requirement>(type);
        else
                return NULL;
}


//
// Return the Designated Requirement. This can be either explicit in the
// Internal Requirements resource, or implicitly generated.
//
const Requirement *SecStaticCode::designatedRequirement()
{
        if (const Requirement *req = internalRequirement(kSecDesignatedRequirementType)) {
                return req;             // explicit in signing data
        } else {
                if (!mDesignatedReq)
                        mDesignatedReq = defaultDesignatedRequirement();
                return mDesignatedReq;
        }
}


//
// Generate the default (implicit) Designated Requirement for this StaticCode.
// This is a heuristic of sorts, and may change over time (for the better, we hope).
//
// The current logic is this:
// * If the code is ad-hoc signed, use the CodeDirectory hash directory.
// * Otherwise, use the form anchor (anchor) and identifier (CodeDirectory identifier).
// ** If the root CA is Apple's, we use the "anchor apple" construct. Otherwise,
//        we default to the leaf (directly signing) certificate.
//
const Requirement *SecStaticCode::defaultDesignatedRequirement()
{
        validateDirectory();            // need the cert chain
        Requirement::Maker maker;
        
        // if this is an ad-hoc (unsigned) object, return a cdhash requirement
        if (flag(kSecCodeSignatureAdhoc)) {
                SHA1 hash;
                hash(codeDirectory(), codeDirectory()->length());
                SHA1::Digest digest;
                hash.finish(digest);
                maker.cdhash(digest);
        } else {
                // always require the identifier
                maker.put(opAnd);
                maker.ident(codeDirectory()->identifier());
                
                SHA1::Digest anchorHash;
                hashOfCertificate(cert(Requirement::anchorCert), anchorHash);
                if (!memcmp(anchorHash, Requirement::appleAnchorHash(), SHA1::digestLength)
#if     defined(TEST_APPLE_ANCHOR)
                        || !memcmp(anchorHash, Requirement::testAppleAnchorHash(), SHA1::digestLength)
#endif
                        )
                        defaultDesignatedAppleAnchor(maker);
                else
                        defaultDesignatedNonAppleAnchor(maker);
        }
                
        return maker();
}

static const uint8_t adcSdkMarker[] = { APPLE_EXTENSION_OID, 2, 1 };
static const CSSM_DATA adcSdkMarkerOID = { sizeof(adcSdkMarker), (uint8_t *)adcSdkMarker };

void SecStaticCode::defaultDesignatedAppleAnchor(Requirement::Maker &maker)
{
        if (isAppleSDKSignature()) {
                // get the Common Name DN element for the leaf
                CFRef<CFStringRef> leafCN;
                MacOSError::check(SecCertificateCopySubjectComponent(cert(Requirement::leafCert),
                        &CSSMOID_CommonName, &leafCN.aref()));
                
                // apple anchor generic and ...
                maker.put(opAnd);
                maker.anchorGeneric();                  // apple generic anchor and...
                // ... leaf[subject.CN] = <leaf's subject> and ...
                maker.put(opAnd);
                maker.put(opCertField);                 // certificate
                maker.put(0);                                   // leaf
                maker.put("subject.CN");                // [subject.CN]
                maker.put(matchEqual);                  // =
                maker.putData(leafCN);                  // <leaf CN>
                // ... cert 1[field.<marker>] exists
                maker.put(opCertGeneric);               // certificate
                maker.put(1);                                   // 1
                maker.putData(adcSdkMarkerOID.Data, adcSdkMarkerOID.Length); // [field.<marker>]
                maker.put(matchExists);                 // exists
                return;
        }

        // otherwise, claim this program for Apple
        maker.anchor();
}

bool SecStaticCode::isAppleSDKSignature()
{
        if (CFArrayRef certChain = certificates())              // got cert chain
                if (CFArrayGetCount(certChain) == 3)            // leaf, one intermediate, anchor
                        if (SecCertificateRef intermediate = cert(1)) // get intermediate
                                if (certificateHasField(intermediate, CssmOid::overlay(adcSdkMarkerOID)))
                                        return true;
        return false;
}

void SecStaticCode::defaultDesignatedNonAppleAnchor(Requirement::Maker &maker)
{
        // get the Organization DN element for the leaf
        CFRef<CFStringRef> leafOrganization;
        MacOSError::check(SecCertificateCopySubjectComponent(cert(Requirement::leafCert),
                &CSSMOID_OrganizationName, &leafOrganization.aref()));

        // now step up the cert chain looking for the first cert with a different one
        int slot = Requirement::leafCert;                                               // start at leaf
        if (leafOrganization) {
                while (SecCertificateRef ca = cert(slot+1)) {           // NULL if you over-run the anchor slot
                        CFRef<CFStringRef> caOrganization;
                        MacOSError::check(SecCertificateCopySubjectComponent(ca, &CSSMOID_OrganizationName, &caOrganization.aref()));
                        if (!caOrganization || CFStringCompare(leafOrganization, caOrganization, 0) != kCFCompareEqualTo)
                                break;
                        slot++;
                }
                if (slot == CFArrayGetCount(mCertChain) - 1)            // went all the way to the anchor...
                        slot = Requirement::anchorCert;                                 // ... so say that
        }
        
        // nail the last cert with the leaf's Organization value
        SHA1::Digest authorityHash;
        hashOfCertificate(cert(slot), authorityHash);
        maker.anchor(slot, authorityHash);
}


//
// Validate a SecStaticCode against the internal requirement of a particular type.
//
void SecStaticCode::validateRequirements(SecRequirementType type, SecStaticCode *target,
        OSStatus nullError /* = noErr */)
{
        DTRACK(CODESIGN_EVAL_STATIC_INTREQ, this, type, target, nullError);
        if (const Requirement *req = internalRequirement(type))
                target->validateRequirements(req, nullError ? nullError : errSecCSReqFailed);
        else if (nullError)
                MacOSError::throwMe(nullError);
        else
                /* accept it */;
}


//
// Validate this StaticCode against an external Requirement
//
void SecStaticCode::validateRequirements(const Requirement *req, OSStatus failure)
{
        assert(req);
        validateDirectory();
        req->validate(Requirement::Context(mCertChain, infoDictionary(), entitlements(), codeDirectory()), failure);
}


//
// Retrieve one certificate from the cert chain.
// Positive and negative indices can be used:
//    [ leaf, intermed-1, ..., intermed-n, anchor ]
//        0       1       ...     -2         -1
// Returns NULL if unavailable for any reason.
//
SecCertificateRef SecStaticCode::cert(int ix)
{
        validateDirectory();            // need cert chain
        if (mCertChain) {
                CFIndex length = CFArrayGetCount(mCertChain);
                if (ix < 0)
                        ix += length;
                if (ix >= 0 && ix < length)
                        return SecCertificateRef(CFArrayGetValueAtIndex(mCertChain, ix));
        }
        return NULL;
}

CFArrayRef SecStaticCode::certificates()
{
        validateDirectory();            // need cert chain
        return mCertChain;
}


//
// Gather (mostly) API-official information about this StaticCode.
//
// This method lives in the twilight between the API and internal layers,
// since it generates API objects (Sec*Refs) for return.
//
CFDictionaryRef SecStaticCode::signingInformation(SecCSFlags flags)
{
        //
        // Start with the pieces that we return even for unsigned code.
        // This makes Sec[Static]CodeRefs useful as API-level replacements
        // of our internal OSXCode objects.
        //
        CFRef<CFMutableDictionaryRef> dict = makeCFMutableDictionary(1,
                kSecCodeInfoMainExecutable, CFTempURL(this->mainExecutablePath()).get()
        );
        
        //
        // If we're not signed, this is all you get
        //
        if (!this->isSigned())
                return dict.yield();
        
        //
        // Add the generic attributes that we always include
        //
        CFDictionaryAddValue(dict, kSecCodeInfoIdentifier, CFTempString(this->identifier()));
        CFDictionaryAddValue(dict, kSecCodeInfoFormat, CFTempString(this->format()));
        CFDictionaryAddValue(dict, kSecCodeInfoSource, CFTempString(this->signatureSource()));
        if (CFDictionaryRef info = this->infoDictionary())
                CFDictionaryAddValue(dict, kSecCodeInfoPList, info);
        CFDictionaryAddValue(dict, kSecCodeInfoUnique, this->cdHash());

        //
        // kSecCSSigningInformation adds information about signing certificates and chains
        //
        if (flags & kSecCSSigningInformation) {
                if (CFArrayRef certs = this->certificates())
                CFDictionaryAddValue(dict, kSecCodeInfoCertificates, certs);
                if (CFDataRef sig = this->signature())
                        CFDictionaryAddValue(dict, kSecCodeInfoCMS, sig);
                if (mTrust)
                        CFDictionaryAddValue(dict, kSecCodeInfoTrust, mTrust);
                if (CFAbsoluteTime time = this->signingTime())
                        if (CFRef<CFDateRef> date = CFDateCreate(NULL, time))
                                CFDictionaryAddValue(dict, kSecCodeInfoTime, date);
        }
        
        //
        // kSecCSRequirementInformation adds information on requirements
        //
        if (flags & kSecCSRequirementInformation) {
                if (const Requirements *reqs = this->internalRequirements()) {
                        CFDictionaryAddValue(dict, kSecCodeInfoRequirements,
                                CFTempString(Dumper::dump(reqs)));
                        CFDictionaryAddValue(dict, kSecCodeInfoRequirementData, CFTempData(*reqs));
                }
                
                const Requirement *dreq = this->designatedRequirement();
                CFRef<SecRequirementRef> dreqRef = (new SecRequirement(dreq))->handle();
                CFDictionaryAddValue(dict, kSecCodeInfoDesignatedRequirement, dreqRef);
                if (this->internalRequirement(kSecDesignatedRequirementType)) { // explicit
                        CFRef<SecRequirementRef> ddreqRef = (new SecRequirement(this->defaultDesignatedRequirement(), true))->handle();
                        CFDictionaryAddValue(dict, kSecCodeInfoImplicitDesignatedRequirement, ddreqRef);
                } else {        // implicit
                        CFDictionaryAddValue(dict, kSecCodeInfoImplicitDesignatedRequirement, dreqRef);
                }
                
           if (CFDataRef ent = this->component(cdEntitlementSlot))
                   CFDictionaryAddValue(dict, kSecCodeInfoEntitlements, ent);
        }
        
        //
        // kSecCSInternalInformation adds internal information meant to be for Apple internal
        // use (SPI), and not guaranteed to be stable. Primarily, this is data we want
        // to reliably transmit through the API wall so that code outside the Security.framework
        // can use it without having to play nasty tricks to get it.
        //
        if (flags & kSecCSInternalInformation) {
                if (mDir)
                        CFDictionaryAddValue(dict, kSecCodeInfoCodeDirectory, mDir);
                CFDictionaryAddValue(dict, kSecCodeInfoCodeOffset, CFTempNumber(mRep->signingBase()));
                if (CFDictionaryRef resources = resourceDictionary())
                        CFDictionaryAddValue(dict, kSecCodeInfoResourceDirectory, resources);
        }
        
        
        //
        // kSecCSContentInformation adds more information about the physical layout
        // of the signed code. This is (only) useful for packaging or patching-oriented
        // applications.
        //
        if (flags & kSecCSContentInformation)
                if (CFRef<CFArrayRef> files = mRep->modifiedFiles())
                        CFDictionaryAddValue(dict, kSecCodeInfoChangedFiles, files);
        
        return dict.yield();
}


//
// Resource validation contexts.
// The default context simply throws a CSError, rudely terminating the operation.
//
SecStaticCode::ValidationContext::~ValidationContext()
{ /* virtual */ }

void SecStaticCode::ValidationContext::reportProblem(OSStatus rc, CFStringRef type, CFTypeRef value)
{
        CSError::throwMe(rc, type, value);
}

void SecStaticCode::CollectingContext::reportProblem(OSStatus rc, CFStringRef type, CFTypeRef value)
{
        if (mStatus == noErr)
                mStatus = rc;                   // record first failure for eventual error return
        if (type) {
                if (!mCollection)
                        mCollection.take(makeCFMutableDictionary());
                CFMutableArrayRef element = CFMutableArrayRef(CFDictionaryGetValue(mCollection, type));
                if (!element) {
                        element = makeCFMutableArray(0);
                        if (!element)
                                CFError::throwMe();
                        CFDictionaryAddValue(mCollection, type, element);
                        CFRelease(element);
                }
                CFArrayAppendValue(element, value);
        }
}

void SecStaticCode::CollectingContext::throwMe()
{
        assert(mStatus != noErr);
        throw CSError(mStatus, mCollection.yield());
}


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