libsecurity_codesigning/lib/opaquewhitelist.cpp

   1 /*
   2  * Copyright (c) 2014 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 #include "opaquewhitelist.h"
  24 #include "csutilities.h"
  25 #include "StaticCode.h"
  26 #include <CoreFoundation/CoreFoundation.h>
  27 #include <Security/SecCodePriv.h>
  28 #include <Security/SecCodeSigner.h>
  29 #include <Security/SecStaticCode.h>
  30 #include <security_utilities/cfutilities.h>
  31 #include <security_utilities/cfmunge.h>
  32 #include <CoreFoundation/CFBundlePriv.h>
  33
  34 namespace Security {
  35 namespace CodeSigning {
  36
  37 using namespace SQLite;
  38
  39
  40 static void traceHash(MessageTrace &trace, const char *key, CFDataRef hash);
  41 static void attachOpaque(SecStaticCodeRef code);
  42
  43
  44 //
  45 // Open the database
  46 //
  47 OpaqueWhitelist::OpaqueWhitelist(const char *path, int flags)
  48         : SQLite::Database(path ? path : opaqueDatabase, flags)
  49 {
  50         SQLite::Statement createConditions(*this,
  51                 "CREATE TABLE IF NOT EXISTS conditions ("
  52                 " label text,"
  53            " weight real not null unique,"
  54            " source text,"
  55            " identifier text,"
  56            " version text,"
  57            " conditions text not null);"
  58         );
  59         createConditions.execute();
  60
  61 }
  62
  63 OpaqueWhitelist::~OpaqueWhitelist()
  64 { /* virtual */ }
  65
  66
  67 //
  68 // Check if a code object is whitelisted
  69 //
  70 bool OpaqueWhitelist::contains(SecStaticCodeRef codeRef, OSStatus reason, bool trace)
  71 {
  72         // make our own copy of the code object, so we can poke at it without disturbing the original
  73         SecPointer<SecStaticCode> code = new SecStaticCode(SecStaticCode::requiredStatic(codeRef)->diskRep());
  74
  75         CFCopyRef<CFDataRef> current = code->cdHash();  // current cdhash
  76         CFDataRef opaque = NULL;        // holds computed opaque cdhash
  77         bool match = false;     // holds final result
  78
  79         if (!current)
  80                 return false;   // unsigned
  81
  82         // collect auxiliary information for trace
  83         CFRef<CFDictionaryRef> info;
  84         std::string team = "";
  85         CFStringRef cfVersion = NULL, cfShortVersion = NULL, cfExecutable = NULL;
  86         if (errSecSuccess == SecCodeCopySigningInformation(code->handle(false), kSecCSSigningInformation, &info.aref())) {
  87                 if (CFStringRef cfTeam = CFStringRef(CFDictionaryGetValue(info, kSecCodeInfoTeamIdentifier)))
  88                         team = cfString(cfTeam);
  89                 if (CFDictionaryRef infoPlist = CFDictionaryRef(CFDictionaryGetValue(info, kSecCodeInfoPList))) {
  90                         if (CFTypeRef version = CFDictionaryGetValue(infoPlist, kCFBundleVersionKey))
  91                                 if (CFGetTypeID(version) == CFStringGetTypeID())
  92                                         cfVersion = CFStringRef(version);
  93                         if (CFTypeRef shortVersion = CFDictionaryGetValue(infoPlist, _kCFBundleShortVersionStringKey))
  94                                 if (CFGetTypeID(shortVersion) == CFStringGetTypeID())
  95                                         cfShortVersion = CFStringRef(shortVersion);
  96                         if (CFTypeRef executable = CFDictionaryGetValue(infoPlist, kCFBundleExecutableKey))
  97                                 if (CFGetTypeID(executable) == CFStringGetTypeID())
  98                                         cfExecutable = CFStringRef(executable);
  99                 }
 100         }
 101
 102         // compute and attach opaque signature
 103         attachOpaque(code->handle(false));
 104         opaque = code->cdHash();
 105
 106         // lookup current cdhash in whitelist
 107         SQLite::Statement lookup(*this, "SELECT opaque FROM whitelist WHERE current=:current");
 108         lookup.bind(":current") = current.get();
 109         while (lookup.nextRow()) {
 110                 CFRef<CFDataRef> expected = lookup[0].data();
 111                 if (CFEqual(opaque, expected)) {
 112                         match = true;   // actual opaque cdhash matches expected
 113                         break;
 114                 }
 115         }
 116
 117         if (trace) {
 118                 // send a trace indicating the result
 119                 MessageTrace trace("com.apple.security.assessment.whitelist2", code->identifier().c_str());
 120                 traceHash(trace, "signature2", current);
 121                 traceHash(trace, "signature3", opaque);
 122                 trace.add("result", match ? "pass" : "fail");
 123                 trace.add("reason", "%d", reason);
 124                 if (!team.empty())
 125                         trace.add("teamid", "%s", team.c_str());
 126                 if (cfVersion)
 127                         trace.add("version", "%s", cfString(cfVersion).c_str());
 128                 if (cfShortVersion)
 129                         trace.add("version2", "%s", cfString(cfShortVersion).c_str());
 130                 if (cfExecutable)
 131                         trace.add("execname", "%s", cfString(cfExecutable).c_str());
 132                 trace.send("");
 133         }
 134
 135         return match;
 136 }
 137
 138
 139 //
 140 // Obtain special validation conditions for a static code, based on database configuration.
 141 //
 142 CFDictionaryRef OpaqueWhitelist::validationConditionsFor(SecStaticCodeRef code)
 143 {
 144         // figure out which team key to use
 145         std::string team = "UNKNOWN";
 146         CFStringRef cfId = NULL;
 147         CFStringRef cfVersion = NULL;
 148         CFRef<CFDictionaryRef> info;    // holds lifetimes for the above
 149         if (errSecSuccess == SecCodeCopySigningInformation(code, kSecCSSigningInformation, &info.aref())) {
 150                 if (CFStringRef cfTeam = CFStringRef(CFDictionaryGetValue(info, kSecCodeInfoTeamIdentifier)))
 151                         team = cfString(cfTeam);
 152                 cfId = CFStringRef(CFDictionaryGetValue(info, kSecCodeInfoIdentifier));
 153                 if (CFDictionaryRef infoPlist = CFDictionaryRef(CFDictionaryGetValue(info, kSecCodeInfoPList)))
 154                         if (CFTypeRef version = CFDictionaryGetValue(infoPlist, _kCFBundleShortVersionStringKey))
 155                                 if (CFGetTypeID(version) == CFStringGetTypeID())
 156                                         cfVersion = CFStringRef(version);
 157         }
 158         if (cfId == NULL)       // unsigned; punt
 159                 return NULL;
 160
 161         // find the highest weight matching condition. We perform no merging and the heaviest rule wins
 162         SQLite::Statement matches(*this,
 163                 "SELECT conditions FROM conditions"
 164                 " WHERE (source = :source or source IS NULL)"
 165                 " AND (identifier = :identifier or identifier is NULL)"
 166                 " AND ((:version IS NULL AND version IS NULL) OR (version = :version OR version IS NULL))"
 167                 " ORDER BY weight DESC"
 168                 " LIMIT 1"
 169         );
 170         matches.bind(":source") = team;
 171         matches.bind(":identifier") = cfString(cfId);
 172         if (cfVersion)
 173                 matches.bind(":version") = cfString(cfVersion);
 174         if (matches.nextRow()) {
 175                 CFTemp<CFDictionaryRef> conditions((const char*)matches[0]);
 176                 return conditions.yield();
 177         }
 178         // no matches
 179         return NULL;
 180 }
 181
 182
 183 //
 184 // Convert a SHA1 hash to hex and add to a trace
 185 //
 186 static void traceHash(MessageTrace &trace, const char *key, CFDataRef hash)
 187 {
 188         if (CFDataGetLength(hash) != sizeof(SHA1::Digest)) {
 189                 trace.add(key, "(unknown format)");
 190         } else {
 191                 const UInt8 *bytes = CFDataGetBytePtr(hash);
 192                 char s[2 * SHA1::digestLength + 1];
 193                 for (unsigned n = 0; n < SHA1::digestLength; n++)
 194                         sprintf(&s[2*n], "%2.2x", bytes[n]);
 195                 trace.add(key, s);
 196         }
 197 }
 198
 199
 200 //
 201 // Add a code object to the whitelist
 202 //
 203 void OpaqueWhitelist::add(SecStaticCodeRef codeRef)
 204 {
 205         // make our own copy of the code object
 206         SecPointer<SecStaticCode> code = new SecStaticCode(SecStaticCode::requiredStatic(codeRef)->diskRep());
 207
 208         CFCopyRef<CFDataRef> current = code->cdHash();
 209         attachOpaque(code->handle(false));      // compute and attach an opaque signature
 210         CFDataRef opaque = code->cdHash();
 211
 212         SQLite::Statement insert(*this, "INSERT OR REPLACE INTO whitelist (current,opaque) VALUES (:current, :opaque)");
 213         insert.bind(":current") = current.get();
 214         insert.bind(":opaque") = opaque;
 215         insert.execute();
 216 }
 217
 218
 219 //
 220 // Generate and attach an ad-hoc opaque signature
 221 //
 222 static void attachOpaque(SecStaticCodeRef code)
 223 {
 224         CFTemp<CFDictionaryRef> rules("{"       // same resource rules as used for collection
 225                 "rules={"
 226                         "'^.*' = #T"
 227                         "'^Info\\.plist$' = {omit=#T,weight=10}"
 228                 "},rules2={"
 229                         "'^(Frameworks|SharedFrameworks|Plugins|Plug-ins|XPCServices|Helpers|MacOS)/' = {nested=#T, weight=0}"
 230                         "'^.*' = #T"
 231                         "'^Info\\.plist$' = {omit=#T,weight=10}"
 232                         "'^[^/]+$' = {top=#T, weight=0}"
 233                 "}"
 234         "}");
 235
 236         CFRef<CFDataRef> signature = CFDataCreateMutable(NULL, 0);
 237         CFTemp<CFDictionaryRef> arguments("{%O=%O, %O=#N, %O=%O}",
 238                 kSecCodeSignerDetached, signature.get(),
 239                 kSecCodeSignerIdentity, /* kCFNull, */
 240                 kSecCodeSignerResourceRules, rules.get());
 241         CFRef<SecCodeSignerRef> signer;
 242         SecCSFlags flags = kSecCSSignOpaque | kSecCSSignNoV1 | kSecCSSignBundleRoot;
 243         MacOSError::check(SecCodeSignerCreate(arguments, flags, &signer.aref()));
 244         MacOSError::check(SecCodeSignerAddSignature(signer, code, kSecCSDefaultFlags));
 245         MacOSError::check(SecCodeSetDetachedSignature(code, signature, kSecCSDefaultFlags));
 246 }
 247
 248
 249 } // end namespace CodeSigning
 250 } // end namespace Security