resources.cpp   [plain text]

/*
 * Copyright (c) 2006-2014 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@
 */

//
// resource directory construction and verification
//
#include "resources.h"
#include "csutilities.h"
#include <security_utilities/unix++.h>
#include <security_utilities/debugging.h>
#include <Security/CSCommon.h>
#include <security_utilities/unix++.h>
#include <security_utilities/cfmunge.h>

// These are pretty nasty, but are a quick safe fix
// to pass information down to the gatekeeper collection tool
extern "C" {
    int GKBIS_DS_Store_Present;
	int GKBIS_Dot_underbar_Present;
	int GKBIS_Num_localizations;
	int GKBIS_Num_files;
	int GKBIS_Num_dirs;
	int GKBIS_Num_symlinks;
}

namespace Security {
namespace CodeSigning {


static string removeTrailingSlash(string path)
{
	if (path.substr(path.length()-2, 2) == "/.")
		return path.substr(0, path.length()-2);
	else if (path.substr(path.length()-1, 1) == "/")
		return path.substr(0, path.length()-1);
	else
		return path;
}

//
// Construction and maintainance
//
ResourceBuilder::ResourceBuilder(const std::string &root, const std::string &relBase,
	CFDictionaryRef rulesDict, bool strict, const MacOSErrorSet& toleratedErrors)
	: mCheckUnreadable(strict && toleratedErrors.find(errSecCSSignatureNotVerifiable) == toleratedErrors.end()),
	  mCheckUnknownType(strict && toleratedErrors.find(errSecCSResourceNotSupported) == toleratedErrors.end())
{
	assert(!root.empty());
	char realroot[PATH_MAX];
	if (realpath(root.c_str(), realroot) == NULL)
		UnixError::throwMe();
	mRoot = realroot;
	if (realpath(removeTrailingSlash(relBase).c_str(), realroot) == NULL)
		UnixError::throwMe();
	mRelBase = realroot;
	if (mRoot != mRelBase && mRelBase != mRoot + "/Contents")
		MacOSError::throwMe(errSecCSBadBundleFormat);
	const char * paths[2] = { mRoot.c_str(), NULL };
	mFTS = fts_open((char * const *)paths, FTS_PHYSICAL | FTS_COMFOLLOW | FTS_NOCHDIR, NULL);
	if (!mFTS)
		UnixError::throwMe();
	mRawRules = rulesDict;
	CFDictionary rules(rulesDict, errSecCSResourceRulesInvalid);
	rules.apply(this, &ResourceBuilder::addRule);
}

ResourceBuilder::~ResourceBuilder()
{
	for (Rules::iterator it = mRules.begin(); it != mRules.end(); ++it)
		delete *it;
	fts_close(mFTS);	// do not check error - it's not worth aborting over (double fault etc.)
}


//
// Parse and add one matching rule
//
void ResourceBuilder::addRule(CFTypeRef key, CFTypeRef value)
{
	string pattern = cfString(key, errSecCSResourceRulesInvalid);
	unsigned weight = 1;
	uint32_t flags = 0;
	if (CFGetTypeID(value) == CFBooleanGetTypeID()) {
		if (value == kCFBooleanFalse)
			flags |= omitted;
	} else {
		CFDictionary rule(value, errSecCSResourceRulesInvalid);
		if (CFNumberRef weightRef = rule.get<CFNumberRef>("weight"))
			weight = cfNumber<unsigned int>(weightRef);
		if (CFBooleanRef omitRef = rule.get<CFBooleanRef>("omit"))
			if (omitRef == kCFBooleanTrue)
				flags |= omitted;
		if (CFBooleanRef optRef = rule.get<CFBooleanRef>("optional"))
			if (optRef == kCFBooleanTrue)
				flags |= optional;
		if (CFBooleanRef nestRef = rule.get<CFBooleanRef>("nested"))
			if (nestRef == kCFBooleanTrue)
				flags |= nested;
	}
	addRule(new Rule(pattern, weight, flags));
}

static bool findStringEndingNoCase(const char *path, const char * end)
{
    size_t len_path = strlen(path);
    size_t len_end = strlen(end);
    
    if (len_path >= len_end) {
        return strcasecmp(path + (len_path - len_end), end) == 0;
    } else
        return false;
}

//
// Locate the next non-ignored file, look up its rule, and return it.
// Returns NULL when we're out of files.
//
void ResourceBuilder::scan(Scanner next)
{
	bool first = true;
    
	while (FTSENT *ent = fts_read(mFTS)) {
		static const char ds_store[] = ".DS_Store";
		const char *relpath = ent->fts_path + mRoot.size() + 1;	// skip prefix + "/"
		std::string rp;
		if (mRelBase != mRoot) {
			assert(mRelBase == mRoot + "/Contents");
			rp = "../" + string(relpath);
			if (rp.substr(0, 12) == "../Contents/")
				rp = rp.substr(12);
			relpath = rp.c_str();
		}
		switch (ent->fts_info) {
		case FTS_F:
			secinfo("rdirenum", "file %s", ent->fts_path);
			GKBIS_Num_files++;
                
			// These are checks for the gatekeeper collection
			static const char underbar[] = "._";
			if (strncasecmp(ent->fts_name, underbar, strlen(underbar)) == 0)
				GKBIS_Dot_underbar_Present++;

			if (strcasecmp(ent->fts_name, ds_store) == 0)
				GKBIS_DS_Store_Present++;

			if (Rule *rule = findRule(relpath))
				if (!(rule->flags & (omitted | exclusion)))
					next(ent, rule->flags, string(relpath), rule);
			break;
		case FTS_SL:
			// symlinks cannot ever be nested code, so quietly convert to resource file
			secinfo("rdirenum", "symlink %s", ent->fts_path);
			GKBIS_Num_symlinks++;

			if (strcasecmp(ent->fts_name, ds_store) == 0)
				MacOSError::throwMe(errSecCSDSStoreSymlink);
                
			if (Rule *rule = findRule(relpath))
				if (!(rule->flags & (omitted | exclusion)))
					next(ent, rule->flags & ~nested, string(relpath), rule);
			break;
		case FTS_D:
			secinfo("rdirenum", "entering %s", ent->fts_path);
			GKBIS_Num_dirs++;

			if (!first) {	// skip root directory (relpath invalid)
				if (Rule *rule = findRule(relpath)) {
					if (rule->flags & nested) {
						if (strchr(ent->fts_name, '.')) {	// nested, has extension -> treat as nested bundle
							next(ent, rule->flags, string(relpath), rule);
							fts_set(mFTS, ent, FTS_SKIP);
						}
					} else if (rule->flags & exclusion) {	// exclude the whole directory
						fts_set(mFTS, ent, FTS_SKIP);
					}
					// else treat as normal directory and descend into it
				}
			}
			// Report the number of localizations
			if (findStringEndingNoCase(ent->fts_name, ".lproj"))
				GKBIS_Num_localizations++;
			first = false;

			break;
		case FTS_DP:
			secinfo("rdirenum", "leaving %s", ent->fts_path);
			break;
		case FTS_DNR:
			secinfo("rdirenum", "cannot read directory %s", ent->fts_path);
			if (mCheckUnreadable)
				MacOSError::throwMe(errSecCSSignatureNotVerifiable);
			break;
		default:
			secinfo("rdirenum", "type %d (errno %d): %s",
				ent->fts_info, ent->fts_errno, ent->fts_path);
			if (mCheckUnknownType)
				MacOSError::throwMe(errSecCSResourceNotSupported);
			break;
		}
	}
}


//
// Check a single for for inclusion in the resource envelope
//
bool ResourceBuilder::includes(string path) const
{
	// process first-directory exclusions
	size_t firstslash = path.find('/');
	if (firstslash != string::npos)
		if (Rule *rule = findRule(path.substr(0, firstslash)))
			if (rule->flags & exclusion)
				return rule->flags & softTarget;
	
	// process full match
	if (Rule *rule = findRule(path))
		return !(rule->flags & (omitted | exclusion)) || (rule->flags & softTarget);
	else
		return false;
}


//
// Find the best-matching resource rule for an alleged resource file.
// Returns NULL if no rule matches, or an exclusion rule applies.
//
ResourceBuilder::Rule *ResourceBuilder::findRule(string path) const
{
	Rule *bestRule = NULL;
	secinfo("rscan", "test %s", path.c_str());
	for (Rules::const_iterator it = mRules.begin(); it != mRules.end(); ++it) {
		Rule *rule = *it;
		secinfo("rscan", "try %s", rule->source.c_str());
		if (rule->match(path.c_str())) {
			secinfo("rscan", "match");
			if (rule->flags & exclusion) {
				secinfo("rscan", "excluded");
				return rule;
			}
			if (!bestRule || rule->weight > bestRule->weight)
				bestRule = rule;


#if TARGET_OS_WATCH
/* rdar://problem/30517969 */
			if (bestRule && bestRule->weight == rule->weight && !(bestRule->flags & omitted) && (rule->flags & omitted))
				bestRule = rule;
#endif
		}
	}
	secinfo("rscan", "choosing %s (%d,0x%x)",
		bestRule ? bestRule->source.c_str() : "NOTHING",
		bestRule ? bestRule->weight : 0,
		bestRule ? bestRule->flags : 0);
	return bestRule;
}


//
// Hash a file and return a CFDataRef with the hash
//
CFDataRef ResourceBuilder::hashFile(const char *path, CodeDirectory::HashAlgorithm type)
{
	UnixPlusPlus::AutoFileDesc fd(path);
	fd.fcntl(F_NOCACHE, true);		// turn off page caching (one-pass)
	RefPointer<DynamicHash> hasher(CodeDirectory::hashFor(type));
	hashFileData(fd, hasher.get());
	vector<Hashing::Byte> digest_vector(hasher->digestLength());
	hasher->finish(digest_vector.data());
	return CFDataCreate(NULL, digest_vector.data(),
						digest_vector.size() * sizeof(Hashing::Byte));
}


//
// Hash a file to multiple hash types and return a dictionary suitable to form a resource seal
//
CFMutableDictionaryRef ResourceBuilder::hashFile(const char *path, CodeDirectory::HashAlgorithms types, bool strictCheck)
{
	UnixPlusPlus::AutoFileDesc fd(path);
	fd.fcntl(F_NOCACHE, true);		// turn off page caching (one-pass)
	if (strictCheck)
		if (fd.hasExtendedAttribute(XATTR_RESOURCEFORK_NAME) || fd.hasExtendedAttribute(XATTR_FINDERINFO_NAME))
			MacOSError::throwMe(errSecCSInvalidAssociatedFileData);
	CFRef<CFMutableDictionaryRef> result = makeCFMutableDictionary();
	CFMutableDictionaryRef resultRef = result;
	CodeDirectory::multipleHashFileData(fd, 0, types, ^(CodeDirectory::HashAlgorithm type, Security::DynamicHash *hasher) {
		size_t length = hasher->digestLength();
		vector<Hashing::Byte> digest_vector(length);
		hasher->finish(digest_vector.data());
		CFDictionaryAddValue(resultRef, CFTempString(hashName(type)), CFTempData(digest_vector.data(), length));
	});
	return result.yield();
}
	
	
std::string ResourceBuilder::hashName(CodeDirectory::HashAlgorithm type)
{
	switch (type) {
	case kSecCodeSignatureHashSHA1:
		return "hash";
	default:
		char name[20];
		snprintf(name, sizeof(name), "hash%d", int(type));
		return name;
	}
}


//
// Regex matching objects
//
ResourceBuilder::Rule::Rule(const std::string &pattern, unsigned w, uint32_t f)
	: weight(w), flags(f), source(pattern)
{
	if (::regcomp(this, pattern.c_str(), REG_EXTENDED | REG_NOSUB))	//@@@ REG_ICASE?
		MacOSError::throwMe(errSecCSResourceRulesInvalid);
	secinfo("csresource", "%p rule %s added (weight %d, flags 0x%x)",
		this, pattern.c_str(), w, f);
}

ResourceBuilder::Rule::~Rule()
{
	::regfree(this);
}

bool ResourceBuilder::Rule::match(const char *s) const
{
	switch (::regexec(this, s, 0, NULL, 0)) {
	case 0:
		return true;
	case REG_NOMATCH:
		return false;
	default:
		MacOSError::throwMe(errSecCSResourceRulesInvalid);
	}
}


std::string ResourceBuilder::escapeRE(const std::string &s)
{
	string r;
	for (string::const_iterator it = s.begin(); it != s.end(); ++it) {
		char c = *it;
		if (strchr("\\[]{}().+*?^$|", c))
			r.push_back('\\');
		r.push_back(c);
	}
	return r;
}


//
// Resource Seals
//
ResourceSeal::ResourceSeal(CFTypeRef it)
	: mDict(NULL), mRequirement(NULL), mLink(NULL), mFlags(0)
{
	if (it == NULL)
		MacOSError::throwMe(errSecCSResourcesInvalid);
	if (CFGetTypeID(it) == CFDataGetTypeID())	// old-style form with just a hash
		mDict.take(cfmake<CFDictionaryRef>("{hash=%O}", it));
	else if (CFGetTypeID(it) == CFDictionaryGetTypeID())
		mDict = CFDictionaryRef(it);
	else
		MacOSError::throwMe(errSecCSResourcesInvalid);

	int optional = 0;
	bool err;
	if (CFDictionaryGetValue(mDict, CFSTR("requirement")))
		err = !cfscan(mDict, "{requirement=%SO,?optional=%B}", &mRequirement, &optional);
	else if (CFDictionaryGetValue(mDict, CFSTR("symlink")))
		err = !cfscan(mDict, "{symlink=%SO,?optional=%B}", &mLink, &optional);
	else
		err = !cfscan(mDict, "{?optional=%B}", &optional);
	if (err)
		MacOSError::throwMe(errSecCSResourcesInvalid);
	if (optional)
		mFlags |= ResourceBuilder::optional;
	if (mRequirement)
		mFlags |= ResourceBuilder::nested;
}
	
	
const Hashing::Byte *ResourceSeal::hash(CodeDirectory::HashAlgorithm type) const
{
	std::string name = ResourceBuilder::hashName(type);
	CFTypeRef hash = CFDictionaryGetValue(mDict, CFTempString(name));
	if (hash == NULL)	// pre-agility fallback
		hash = CFDictionaryGetValue(mDict, CFSTR("hash"));
	if (hash == NULL || CFGetTypeID(hash) != CFDataGetTypeID())
		MacOSError::throwMe(errSecCSResourcesInvalid);
	return CFDataGetBytePtr(CFDataRef(hash));
}


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