Security/libsecurity_codesigning/lib/policydb.cpp

   1 /*
   2  * Copyright (c) 2011-2013 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 "cs.h"
  24 #include "policydb.h"
  25 #include "policyengine.h"
  26 #include <Security/CodeSigning.h>
  27 #include <security_utilities/cfutilities.h>
  28 #include <security_utilities/cfmunge.h>
  29 #include <security_utilities/blob.h>
  30 #include <security_utilities/logging.h>
  31 #include <security_utilities/simpleprefs.h>
  32 #include <security_utilities/logging.h>
  33 #include "csdatabase.h"
  34
  35 #include <dispatch/dispatch.h>
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <notify.h>
  39
  40 namespace Security {
  41 namespace CodeSigning {
  42
  43
  44 using namespace SQLite;
  45
  46
  47 //
  48 // Determine the database path
  49 //
  50 static const char *dbPath()
  51 {
  52         if (const char *s = getenv("SYSPOLICYDATABASE"))
  53                 return s;
  54         return defaultDatabase;
  55 }
  56
  57
  58 //
  59 // Help mapping API-ish CFString keys to more convenient internal enumerations
  60 //
  61 typedef struct {
  62         const CFStringRef &cstring;
  63         uint enumeration;
  64 } StringMap;
  65
  66 static uint mapEnum(CFDictionaryRef context, CFStringRef attr, const StringMap *map, uint value = 0)
  67 {
  68         if (context)
  69                 if (CFTypeRef value = CFDictionaryGetValue(context, attr))
  70                         for (const StringMap *mp = map; mp->cstring; ++mp)
  71                                 if (CFEqual(mp->cstring, value))
  72                                         return mp->enumeration;
  73         return value;
  74 }
  75
  76 static const StringMap mapType[] = {
  77         { kSecAssessmentOperationTypeExecute, kAuthorityExecute },
  78         { kSecAssessmentOperationTypeInstall, kAuthorityInstall },
  79         { kSecAssessmentOperationTypeOpenDocument, kAuthorityOpenDoc },
  80         { NULL }
  81 };
  82
  83 AuthorityType typeFor(CFDictionaryRef context, AuthorityType type /* = kAuthorityInvalid */)
  84 {
  85         return mapEnum(context, kSecAssessmentContextKeyOperation, mapType, type);
  86 }
  87
  88 CFStringRef typeNameFor(AuthorityType type)
  89 {
  90         for (const StringMap *mp = mapType; mp->cstring; ++mp)
  91                 if (type == mp->enumeration)
  92                         return mp->cstring;
  93         return CFStringCreateWithFormat(NULL, NULL, CFSTR("type %d"), type);
  94 }
  95
  96
  97 //
  98 // Open the database
  99 //
 100 PolicyDatabase::PolicyDatabase(const char *path, int flags)
 101         : SQLite::Database(path ? path : dbPath(), flags),
 102           mLastExplicitCheck(0)
 103 {
 104         // sqlite3 doesn't do foreign key support by default, have to turn this on per connection
 105         SQLite::Statement foreign(*this, "PRAGMA foreign_keys = true");
 106         foreign.execute();
 107
 108         // Try upgrade processing if we may be open for write.
 109         // Ignore any errors (we may have been downgraded to read-only)
 110         // and try again later.
 111         if (openFlags() & SQLITE_OPEN_READWRITE)
 112                 try {
 113                         upgradeDatabase();
 114                         installExplicitSet(gkeAuthFile, gkeSigsFile);
 115                 } catch(...) {
 116                 }
 117 }
 118
 119 PolicyDatabase::~PolicyDatabase()
 120 { /* virtual */ }
 121
 122
 123 //
 124 // Quick-check the cache for a match.
 125 // Return true on a cache hit, false on failure to confirm a hit for any reason.
 126 //
 127 bool PolicyDatabase::checkCache(CFURLRef path, AuthorityType type, SecAssessmentFlags flags, CFMutableDictionaryRef result)
 128 {
 129         // we currently don't use the cache for anything but execution rules
 130         if (type != kAuthorityExecute)
 131                 return false;
 132
 133         CFRef<SecStaticCodeRef> code;
 134         MacOSError::check(SecStaticCodeCreateWithPath(path, kSecCSDefaultFlags, &code.aref()));
 135         if (SecStaticCodeCheckValidity(code, kSecCSBasicValidateOnly, NULL) != errSecSuccess)
 136                 return false;   // quick pass - any error is a cache miss
 137         CFRef<CFDictionaryRef> info;
 138         MacOSError::check(SecCodeCopySigningInformation(code, kSecCSDefaultFlags, &info.aref()));
 139         CFDataRef cdHash = CFDataRef(CFDictionaryGetValue(info, kSecCodeInfoUnique));
 140
 141         // check the cache table for a fast match
 142         SQLite::Statement cached(*this, "SELECT object.allow, authority.label, authority FROM object, authority"
 143                 " WHERE object.authority = authority.id AND object.type = :type AND object.hash = :hash AND authority.disabled = 0"
 144                 " AND JULIANDAY('now') < object.expires;");
 145         cached.bind(":type").integer(type);
 146         cached.bind(":hash") = cdHash;
 147         if (cached.nextRow()) {
 148                 bool allow = int(cached[0]);
 149                 const char *label = cached[1];
 150                 SQLite::int64 auth = cached[2];
 151                 SYSPOLICY_ASSESS_CACHE_HIT();
 152
 153                 // If its allowed, lets do a full validation unless if
 154                 // we are overriding the assessement, since that force
 155                 // the verdict to 'pass' at the end
 156
 157                 if (allow && !overrideAssessment(flags))
 158                     MacOSError::check(SecStaticCodeCheckValidity(code, kSecCSDefaultFlags, NULL));
 159
 160                 cfadd(result, "{%O=%B}", kSecAssessmentAssessmentVerdict, allow);
 161                 PolicyEngine::addAuthority(flags, result, label, auth, kCFBooleanTrue);
 162                 return true;
 163         }
 164         return false;
 165 }
 166
 167
 168 //
 169 // Purge the object cache of all expired entries.
 170 // These are meant to run within the caller's transaction.
 171 //
 172 void PolicyDatabase::purgeAuthority()
 173 {
 174         SQLite::Statement cleaner(*this,
 175                 "DELETE FROM authority WHERE expires <= JULIANDAY('now');");
 176         cleaner.execute();
 177 }
 178
 179 void PolicyDatabase::purgeObjects()
 180 {
 181         SQLite::Statement cleaner(*this,
 182                 "DELETE FROM object WHERE expires <= JULIANDAY('now');");
 183         cleaner.execute();
 184 }
 185
 186 void PolicyDatabase::purgeObjects(double priority)
 187 {
 188         SQLite::Statement cleaner(*this,
 189                 "DELETE FROM object WHERE expires <= JULIANDAY('now') OR (SELECT priority FROM authority WHERE id = object.authority) <= :priority;");
 190         cleaner.bind(":priority") = priority;
 191         cleaner.execute();
 192 }
 193
 194
 195 //
 196 // Database migration
 197 //
 198 std::string PolicyDatabase::featureLevel(const char *name)
 199 {
 200         SQLite::Statement feature(*this, "SELECT value FROM feature WHERE name=:name");
 201         feature.bind(":name") = name;
 202         if (feature.nextRow()) {
 203                 if (const char *value = feature[0])
 204                         return value;
 205                 else
 206                         return "default";       // old engineering versions may have NULL values; tolerate this
 207         }
 208         return "";              // new feature (no level)
 209 }
 210
 211 void PolicyDatabase::addFeature(const char *name, const char *value, const char *remarks)
 212 {
 213         SQLite::Statement feature(*this, "INSERT OR REPLACE INTO feature (name,value,remarks) VALUES(:name, :value, :remarks)");
 214         feature.bind(":name") = name;
 215         feature.bind(":value") = value;
 216         feature.bind(":remarks") = remarks;
 217         feature.execute();
 218 }
 219
 220 void PolicyDatabase::simpleFeature(const char *feature, void (^perform)())
 221 {
 222         if (!hasFeature(feature)) {
 223                 SQLite::Transaction update(*this);
 224                 perform();
 225                 addFeature(feature, "upgraded", "upgraded");
 226                 update.commit();
 227         }
 228 }
 229
 230 void PolicyDatabase::simpleFeature(const char *feature, const char *sql)
 231 {
 232         simpleFeature(feature, ^{
 233                 SQLite::Statement perform(*this, sql);
 234                 perform.execute();
 235         });
 236 }
 237
 238
 239 void PolicyDatabase::upgradeDatabase()
 240 {
 241         simpleFeature("bookmarkhints",
 242                 "CREATE TABLE bookmarkhints ("
 243                         "  id INTEGER PRIMARY KEY AUTOINCREMENT, "
 244                         "  bookmark BLOB,"
 245                         "  authority INTEGER NOT NULL"
 246                         "     REFERENCES authority(id) ON DELETE CASCADE"
 247                         ")");
 248
 249         simpleFeature("codesignedpackages", ^{
 250                 SQLite::Statement update(*this,
 251                         "UPDATE authority"
 252                         " SET requirement = 'anchor apple generic and certificate 1[field.1.2.840.113635.100.6.2.6] exists and "
 253                                 "(certificate leaf[field.1.2.840.113635.100.6.1.14] or certificate leaf[field.1.2.840.113635.100.6.1.13])'"
 254                         " WHERE type = 2 and label = 'Developer ID' and flags & :flag");
 255                 update.bind(":flag") = kAuthorityFlagDefault;
 256                 update.execute();
 257         });
 258
 259         simpleFeature("filter_unsigned",
 260                 "ALTER TABLE authority ADD COLUMN filter_unsigned TEXT NULL"
 261                 );
 262
 263         simpleFeature("strict_apple_installer", ^{
 264                 SQLite::Statement update(*this,
 265                         "UPDATE authority"
 266                         " SET requirement = 'anchor apple generic and certificate 1[subject.CN] = \"Apple Software Update Certification Authority\"'"
 267                         " WHERE flags & :flag AND label = 'Apple Installer'");
 268                 update.bind(":flag") = kAuthorityFlagDefault;
 269                 update.execute();
 270                 SQLite::Statement add(*this,
 271                         "INSERT INTO authority (type, label, flags, requirement)"
 272                         " VALUES (2, 'Mac App Store', :flags, 'anchor apple generic and certificate leaf[field.1.2.840.113635.100.6.1.10] exists')");
 273                 add.bind(":flags") = kAuthorityFlagDefault;
 274                 add.execute();
 275         });
 276 }
 277
 278
 279 //
 280 // Install Gatekeeper override (GKE) data.
 281 // The arguments are paths to the authority and signature files.
 282 //
 283 void PolicyDatabase::installExplicitSet(const char *authfile, const char *sigfile)
 284 {
 285         // only try this every gkeCheckInterval seconds
 286         time_t now = time(NULL);
 287         if (mLastExplicitCheck + gkeCheckInterval > now)
 288                 return;
 289         mLastExplicitCheck = now;
 290
 291         try {
 292                 if (CFRef<CFDataRef> authData = cfLoadFile(authfile)) {
 293                         CFDictionary auth(CFRef<CFDictionaryRef>(makeCFDictionaryFrom(authData)), errSecCSDbCorrupt);
 294                         CFDictionaryRef content = auth.get<CFDictionaryRef>(CFSTR("authority"));
 295                         std::string authUUID = cfString(auth.get<CFStringRef>(CFSTR("uuid")));
 296                         if (authUUID.empty()) {
 297                                 secdebug("gkupgrade", "no uuid in auth file; ignoring gke.auth");
 298                                 return;
 299                         }
 300                         std::string dbUUID;
 301                         SQLite::Statement uuidQuery(*this, "SELECT value FROM feature WHERE name='gke'");
 302                         if (uuidQuery.nextRow())
 303                                 dbUUID = (const char *)uuidQuery[0];
 304                         if (dbUUID == authUUID) {
 305                                 secdebug("gkupgrade", "gke.auth already present, ignoring");
 306                                 return;
 307                         }
 308                         Syslog::notice("loading GKE %s (replacing %s)", authUUID.c_str(), dbUUID.empty() ? "nothing" : dbUUID.c_str());
 309
 310                         // first, load code signatures. This is pretty much idempotent
 311                         if (sigfile)
 312                                 if (FILE *sigs = fopen(sigfile, "r")) {
 313                                         unsigned count = 0;
 314                                     SignatureDatabaseWriter db;
 315                                         while (const BlobCore *blob = BlobCore::readBlob(sigs)) {
 316                                                 db.storeCode(blob, "<remote>");
 317                                                 count++;
 318                                         }
 319                                         secdebug("gkupgrade", "%d detached signature(s) loaded from override data", count);
 320                                         fclose(sigs);
 321                                 }
 322
 323                         // start transaction (atomic from here on out)
 324                         SQLite::Transaction loadAuth(*this, SQLite::Transaction::exclusive, "GKE_Upgrade");
 325
 326                         // purge prior authority data
 327                         SQLite::Statement purge(*this, "DELETE FROM authority WHERE flags & :flag");
 328                         purge.bind(":flag") = kAuthorityFlagWhitelist;
 329                         purge();
 330
 331                         // load new data
 332                         CFIndex count = CFDictionaryGetCount(content);
 333                         CFStringRef keys[count];
 334                         CFDictionaryRef values[count];
 335                         CFDictionaryGetKeysAndValues(content, (const void **)keys, (const void **)values);
 336
 337                         SQLite::Statement insert(*this, "INSERT INTO authority (type, allow, requirement, label, filter_unsigned, flags, remarks)"
 338                                 " VALUES (:type, 1, :requirement, 'GKE', :filter, :flags, :path)");
 339                         for (CFIndex n = 0; n < count; n++) {
 340                                 CFDictionary info(values[n], errSecCSDbCorrupt);
 341                                 uint32_t flags = kAuthorityFlagWhitelist;
 342                                 if (CFNumberRef versionRef = info.get<CFNumberRef>("version")) {
 343                                         int version = cfNumber<int>(versionRef);
 344                                         if (version >= 2)
 345                                                 flags |= kAuthorityFlagWhitelistV2;
 346                                 }
 347                                 insert.reset();
 348                                 insert.bind(":type") = cfString(info.get<CFStringRef>(CFSTR("type")));
 349                                 insert.bind(":path") = cfString(info.get<CFStringRef>(CFSTR("path")));
 350                                 insert.bind(":requirement") = "cdhash H\"" + cfString(info.get<CFStringRef>(CFSTR("cdhash"))) + "\"";
 351                                 insert.bind(":filter") = cfString(info.get<CFStringRef>(CFSTR("screen")));
 352                                 insert.bind(":flags").integer(flags);
 353                                 insert();
 354                         }
 355
 356                         // we just changed the authority configuration at priority zero
 357                         this->purgeObjects(0);
 358
 359                         // update version and commit
 360                         addFeature("gke", authUUID.c_str(), "gke loaded");
 361                         loadAuth.commit();
 362                 }
 363         } catch (...) {
 364                 secdebug("gkupgrade", "exception during GKE upgrade");
 365         }
 366 }
 367
 368
 369 //
 370 // Check the override-enable master flag
 371 //
 372 #define SP_ENABLE_KEY CFSTR("enabled")
 373 #define SP_ENABLED CFSTR("yes")
 374 #define SP_DISABLED CFSTR("no")
 375
 376 bool overrideAssessment(SecAssessmentFlags flags /* = 0 */)
 377 {
 378         static bool enabled = true;
 379         static dispatch_once_t once;
 380         static int token = -1;
 381         static int have_token = 0;
 382         static dispatch_queue_t queue;
 383         int check;
 384
 385         if (flags & kSecAssessmentFlagEnforce)  // explicitly disregard disables (force on)
 386                 return false;
 387
 388         if (have_token && notify_check(token, &check) == NOTIFY_STATUS_OK && !check)
 389                 return !enabled;
 390
 391         dispatch_once(&once, ^{
 392                 if (notify_register_check(kNotifySecAssessmentMasterSwitch, &token) == NOTIFY_STATUS_OK)
 393                         have_token = 1;
 394                 queue = dispatch_queue_create("com.apple.SecAssessment.assessment", NULL);
 395              });
 396
 397         dispatch_sync(queue, ^{
 398                 /* upgrade configuration from emir, ignore all error since we might not be able to write to */
 399                 if (::access(visibleSecurityFlagFile, F_OK) == 0) {
 400                         try {
 401                                 setAssessment(true);
 402                                 ::unlink(visibleSecurityFlagFile);
 403                         } catch (...) {
 404                         }
 405                         enabled = true;
 406                         return;
 407                 }
 408
 409                 try {
 410                         Dictionary * prefsDict = Dictionary::CreateDictionary(prefsFile);
 411                         if (prefsDict == NULL)
 412                                 return;
 413
 414                         CFStringRef value = prefsDict->getStringValue(SP_ENABLE_KEY);
 415                         if (value && CFStringCompare(value, SP_DISABLED, 0) == 0)
 416                                 enabled = false;
 417                         else
 418                                 enabled = true;
 419                         delete prefsDict;
 420                 } catch(...) {
 421                 }
 422         });
 423
 424         return !enabled;
 425 }
 426
 427 void setAssessment(bool masterSwitch)
 428 {
 429         MutableDictionary *prefsDict = MutableDictionary::CreateMutableDictionary(prefsFile);
 430         if (prefsDict == NULL)
 431                 prefsDict = new MutableDictionary::MutableDictionary();
 432         prefsDict->setValue(SP_ENABLE_KEY, masterSwitch ? SP_ENABLED : SP_DISABLED);
 433         prefsDict->writePlistToFile(prefsFile);
 434         delete prefsDict;
 435
 436         /* make sure permissions is right */
 437         ::chmod(prefsFile, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
 438
 439         notify_post(kNotifySecAssessmentMasterSwitch);
 440
 441         /* reset the automatic rearm timer */
 442         resetRearmTimer("masterswitch");
 443 }
 444
 445
 446 //
 447 // Reset or query the automatic rearm timer
 448 //
 449 void resetRearmTimer(const char *event)
 450 {
 451         CFRef<CFDateRef> now = CFDateCreate(NULL, CFAbsoluteTimeGetCurrent());
 452         CFTemp<CFDictionaryRef> info("{event=%s, timestamp=%O}", event, now.get());
 453         CFRef<CFDataRef> infoData = makeCFData(info.get());
 454         UnixPlusPlus::AutoFileDesc fd(rearmTimerFile, O_WRONLY | O_CREAT | O_TRUNC, 0644);
 455         fd.write(CFDataGetBytePtr(infoData), CFDataGetLength(infoData));
 456 }
 457
 458 bool queryRearmTimer(CFTimeInterval &delta)
 459 {
 460         if (CFRef<CFDataRef> infoData = cfLoadFile(rearmTimerFile)) {
 461                 if (CFRef<CFDictionaryRef> info = makeCFDictionaryFrom(infoData)) {
 462                         CFDateRef timestamp = (CFDateRef)CFDictionaryGetValue(info, CFSTR("timestamp"));
 463                         if (timestamp && CFGetTypeID(timestamp) == CFDateGetTypeID()) {
 464                                 delta = CFAbsoluteTimeGetCurrent() - CFDateGetAbsoluteTime(timestamp);
 465                                 return true;
 466                         }
 467                 }
 468                 MacOSError::throwMe(errSecCSDbCorrupt);
 469         }
 470         return false;
 471 }
 472
 473
 474 } // end namespace CodeSigning
 475 } // end namespace Security