securityd/src/acl_keychain.cpp

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  23
  24
  25 //
  26 // acl_keychain - a subject type for the protected-path
  27 //                                keychain prompt interaction model.
  28 //
  29 // Arguments in CSSM_LIST form:
  30 //      list[1] = CssmData: CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR structure
  31 //      list[2] = CssmData: Descriptive String (presented to user in protected dialogs)
  32 // For legacy compatibility, we accept a single-entry form
  33 //      list[1] = CssmData: Descriptive String
  34 // which defaults to a particular CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR structure value.
  35 // This is never produced by current code, and is considered purely a legacy feature.
  36 //
  37 // On-disk (flattened) representation:
  38 // In order to accommodate legacy formats nicely, we use the binary-versioning feature
  39 // of the ACL machinery. Version 0 is the legacy format (storing only the description
  40 // string), while Version 1 contains both selector and description. We are now always
  41 // writing version-1 data, but will continue to recognize version-0 data indefinitely
  42 // for really, really old keychain items.
  43 //
  44 #include "acl_keychain.h"
  45 #include "agentquery.h"
  46 #include "acls.h"
  47 #include "connection.h"
  48 #include "database.h"
  49 #include "server.h"
  50 #include <security_utilities/debugging.h>
  51 #include <security_utilities/logging.h>
  52 #include <security_cdsa_utilities/osxverifier.h>
  53 #include <algorithm>
  54 #include <sys/csr.h>
  55
  56 #include <Security/AuthorizationTagsPriv.h>
  57
  58 #define ACCEPT_LEGACY_FORM 1
  59
  60 //
  61 // Initialize static memory.
  62 //
  63 uint32_t KeychainPromptAclSubject::promptsValidated = 0;
  64
  65
  66 //
  67 // The default for the selector structure.
  68 //
  69 CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR KeychainPromptAclSubject::defaultSelector = {
  70         CSSM_ACL_KEYCHAIN_PROMPT_CURRENT_VERSION,       // version
  71         0                                                                                       // flags
  72 };
  73
  74
  75 //
  76 // If we have a KeychainPromptAclSubject, we want KeychainMigrator to have
  77 // access even if we don't have the "pop ui" credential. Do the code signing
  78 // check first, then process this ACL as normal.
  79 //
  80 bool KeychainPromptAclSubject::validates(const AclValidationContext &ctx) const
  81 {
  82     Process &process = Server::process();
  83     if (process.checkAppleSigned() && process.hasEntitlement(migrationEntitlement)) {
  84         Syslog::info("bypassing keychain prompt for keychain migrator");
  85         secnotice("kcacl", "bypassing keychain prompt for keychain migrator");
  86         return true;   // migrator client -> automatic win
  87     }
  88
  89     // Also, mark down that we evaluated a prompt ACL. We want to record this for testing even if the client did not pass credentials for UI
  90     // (so that tests can disable prompts but still detect if one would have popped)
  91     promptsValidated++;
  92
  93     return SimpleAclSubject::validates(ctx);
  94 }
  95
  96
  97 //
  98 // Validate a credential set against this subject.
  99 //
 100 bool KeychainPromptAclSubject::validates(const AclValidationContext &context,
 101     const TypedList &sample) const
 102 {
 103     // Try to grab a common lock. We'll need it in queryUser, but we can't get
 104     // it in validateExplicitly since other callers have it.
 105     SecurityServerEnvironment *env = context.environment<SecurityServerEnvironment>();
 106     StMaybeLock<Mutex> _(env && env->database && env->database->hasCommon() ? &env->database->common() : NULL);
 107
 108         return validateExplicitly(context, ^{
 109                 if (SecurityServerEnvironment *env = context.environment<SecurityServerEnvironment>()) {
 110             Process& process = Server::process();
 111                         StLock<Mutex> _(process);
 112                         RefPointer<AclSubject> subject = process.copyAclSubject();
 113                         if (SecurityServerAcl::addToStandardACL(context, subject)) {
 114                 if(env->database && env->database->dbVersion() >= CommonBlob::version_partition) {
 115                     env->acl.addClientPartitionID(process);
 116                 }
 117                         }
 118                 }
 119         });
 120 }
 121
 122 bool KeychainPromptAclSubject::validateExplicitly(const AclValidationContext &context, void (^alwaysAllow)()) const
 123 {
 124     if (SecurityServerEnvironment *env = context.environment<SecurityServerEnvironment>()) {
 125                 Process &process = Server::process();
 126                 secnotice("kcacl", "Keychain query for process %d (UID %d)", process.pid(), process.uid());
 127
 128                 // assemble the effective validity mode mask
 129                 uint32_t mode = Maker::defaultMode;
 130                 const uint16_t &flags = selector.flags;
 131                 if (flags & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED_ACT)
 132                         mode = (mode & ~CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED) | (flags & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED);
 133                 if (flags & CSSM_ACL_KEYCHAIN_PROMPT_INVALID_ACT)
 134                         mode = (mode & ~CSSM_ACL_KEYCHAIN_PROMPT_INVALID) | (flags & CSSM_ACL_KEYCHAIN_PROMPT_INVALID);
 135
 136                 // determine signed/validity status of client, without reference to any particular Code Requirement
 137                 OSStatus validation = errSecCSStaticCodeNotFound;
 138                 {
 139                         StLock<Mutex> _(process);
 140                         Server::active().longTermActivity();
 141
 142                         validation = process.checkValidity(kSecCSDefaultFlags, NULL);
 143
 144                         switch (validation)
 145                         {
 146                                 case noErr:                                                     // client is signed and valid
 147                                 {
 148                                         secnotice("kcacl", "client is valid, proceeding");
 149                     // This should almost always be handled by the check in KeychainPromptAclSubject::validate, but check again just in case
 150                     if (process.checkAppleSigned() && process.hasEntitlement(migrationEntitlement)) {
 151                         Syslog::info("bypassing keychain prompt for keychain migrator");
 152                         secnotice("kcacl", "bypassing keychain prompt for keychain migrator");
 153                                                 return true;    // migrator client -> automatic win
 154                     }
 155                                 }
 156                                 break;
 157
 158                                 case errSecCSUnsigned:
 159                                 {                       // client is not signed
 160                                         if (!(mode & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED)) {
 161                         Syslog::info("supressing keychain prompt for unsigned client %s(%d)", process.getPath().c_str(), process.pid());
 162                         secnotice("kcacl", "supressing keychain prompt for unsigned client %s(%d)", process.getPath().c_str(), process.pid());
 163                                                 return false;
 164                                         }
 165                                 }
 166                                 break;
 167
 168                                 case errSecCSSignatureFailed:           // client signed but signature is broken
 169                                 case errSecCSGuestInvalid:                      // client signed but dynamically invalid
 170                                 case errSecCSStaticCodeNotFound:        // client not on disk (or unreadable)
 171                                 {
 172                                         if (!(mode & CSSM_ACL_KEYCHAIN_PROMPT_INVALID)) {
 173                                                 secnotice("kcacl", "client is invalid, suppressing prompt");
 174                                                 Syslog::info("suppressing keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 175                         secnotice("kcacl", "suppressing keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 176                                                 return false;
 177                                         }
 178                                         Syslog::info("attempting keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 179                     secnotice("kcacl", "attempting keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 180                                 }
 181                                 break;
 182
 183                                 default:                                                        // something else went wrong
 184                     Syslog::info("suppressing keychain prompt %s(%d); code signing check failed rc=%d", process.getPath().c_str(), process.pid(),  (int32_t) validation);
 185                     secnotice("kcacl", "suppressing keychain prompt %s(%d); code signing check failed rc=%d", process.getPath().c_str(), process.pid(),  (int32_t) validation);
 186                                         return false;
 187                         }
 188                 }
 189
 190                 // At this point, we're committed to try to Pop The Question. Now, how?
 191         Syslog::info("displaying keychain prompt for %s(%d)", process.getPath().c_str(), process.pid());
 192         secnotice("kcacl", "displaying keychain prompt for %s(%d)", process.getPath().c_str(), process.pid());
 193
 194                 // does the user need to type in the passphrase?
 195         const Database *db = env->database;
 196         bool needPassphrase = db && (selector.flags & CSSM_ACL_KEYCHAIN_PROMPT_REQUIRE_PASSPHRASE);
 197
 198                 // an application (i.e. Keychain Access.app :-) can force this option
 199                 if (validation == noErr) {
 200                         StLock<Mutex> _(process);
 201                         CFRef<CFDictionaryRef> dict;
 202                         if (process.copySigningInfo(kSecCSDefaultFlags, &dict.aref()) == noErr)
 203                                 if (CFDictionaryRef info = CFDictionaryRef(CFDictionaryGetValue(dict, kSecCodeInfoPList)))
 204                                         needPassphrase |=
 205                                                 (CFDictionaryGetValue(info, CFSTR("SecForcePassphrasePrompt")) != NULL);
 206                 }
 207
 208                 // pop The Question
 209                 if (db && db->belongsToSystem() && !hasAuthorizedForSystemKeychain()) {
 210                         QueryKeychainAuth query;
 211                         query.inferHints(Server::process());
 212                         if (query(db ? db->dbName() : NULL, description.c_str(), context.authorization(), NULL) != SecurityAgent::noReason)
 213                                 return false;
 214                         return true;
 215                 } else {
 216                         QueryKeychainUse query(needPassphrase, db);
 217                         query.inferHints(Server::process());
 218                         query.addHint(AGENT_HINT_CLIENT_VALIDITY, &validation, sizeof(validation));
 219                         if (query.queryUser(db ? db->dbName() : NULL,
 220                                 description.c_str(), context.authorization()) != SecurityAgent::noReason)
 221                                 return false;
 222
 223                         // process an "always allow..." response
 224                         if (query.remember && validation != errSecCSStaticCodeNotFound) {
 225                                 alwaysAllow();
 226                         }
 227
 228                         // finally, return the actual user response
 229                         return query.allow;
 230                 }
 231     }
 232         return false;        // default to deny without prejudice
 233 }
 234
 235
 236 //
 237 // Make a copy of this subject in CSSM_LIST form
 238 //
 239 CssmList KeychainPromptAclSubject::toList(Allocator &alloc) const
 240 {
 241         // always issue new (non-legacy) form
 242         return TypedList(alloc, CSSM_ACL_SUBJECT_TYPE_KEYCHAIN_PROMPT,
 243                 new(alloc) ListElement(alloc, CssmData::wrap(selector)),
 244         new(alloc) ListElement(alloc, description));
 245 }
 246
 247 //
 248 // Has the caller recently authorized in such a way as to render unnecessary
 249 // the usual QueryKeychainAuth dialog?  (The right is specific to Keychain
 250 // Access' way of editing a system keychain.)
 251 //
 252 bool KeychainPromptAclSubject::hasAuthorizedForSystemKeychain() const
 253 {
 254 //      string rightString = "system.keychain.modify";
 255 //      return Server::session().isRightAuthorized(rightString, Server::connection(), false/*no UI*/);
 256         return false;
 257 }
 258
 259
 260
 261 //
 262 // Create a KeychainPromptAclSubject
 263 //
 264 uint32_t KeychainPromptAclSubject::Maker::defaultMode;
 265
 266 KeychainPromptAclSubject *KeychainPromptAclSubject::Maker::make(const TypedList &list) const
 267 {
 268         switch (list.length()) {
 269 #if ACCEPT_LEGACY_FORM
 270         case 2: // legacy case: just description
 271                 {
 272                         ListElement *params[1];
 273                         crack(list, 1, params, CSSM_LIST_ELEMENT_DATUM);
 274                         return new KeychainPromptAclSubject(*params[0], defaultSelector);
 275                 }
 276 #endif //ACCEPT_LEGACY_FORM
 277         case 3: // standard case: selector + description
 278                 {
 279                         ListElement *params[2];
 280                         crack(list, 2, params, CSSM_LIST_ELEMENT_DATUM, CSSM_LIST_ELEMENT_DATUM);
 281                         return new KeychainPromptAclSubject(*params[1],
 282                                 *params[0]->data().interpretedAs<CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR>(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE));
 283                 }
 284         default:
 285                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 286         }
 287 }
 288
 289 KeychainPromptAclSubject *KeychainPromptAclSubject::Maker::make(Version version,
 290         Reader &pub, Reader &) const
 291 {
 292         CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR selector;
 293         const char *description;
 294         switch (version) {
 295         case pumaVersion:
 296                 selector = defaultSelector;
 297                 pub(description);
 298                 break;
 299         case jaguarVersion:
 300                 pub(selector);
 301                 selector.version = n2h(selector.version);
 302                 selector.flags = n2h(selector.flags);
 303                 pub(description);
 304                 break;
 305         default:
 306                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 307         }
 308         return new KeychainPromptAclSubject(description, selector);
 309 }
 310
 311 KeychainPromptAclSubject::KeychainPromptAclSubject(string descr,
 312         const CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR &sel)
 313         : SimpleAclSubject(CSSM_ACL_SUBJECT_TYPE_KEYCHAIN_PROMPT),
 314         selector(sel), description(descr)
 315 {
 316         // check selector version
 317         if (selector.version != CSSM_ACL_KEYCHAIN_PROMPT_CURRENT_VERSION)
 318                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 319
 320         // always use the latest binary version
 321         version(currentVersion);
 322 }
 323
 324
 325 //
 326 // Export the subject to a memory blob
 327 //
 328 void KeychainPromptAclSubject::exportBlob(Writer::Counter &pub, Writer::Counter &priv)
 329 {
 330         if (version() != 0) {
 331                 selector.version = h2n (selector.version);
 332                 selector.flags = h2n (selector.flags);
 333                 pub(selector);
 334         }
 335
 336     pub.insert(description.size() + 1);
 337 }
 338
 339 void KeychainPromptAclSubject::exportBlob(Writer &pub, Writer &priv)
 340 {
 341         if (version() != 0) {
 342                 selector.version = h2n (selector.version);
 343                 selector.flags = h2n (selector.flags);
 344                 pub(selector);
 345         }
 346     pub(description.c_str());
 347 }
 348
 349
 350 #ifdef DEBUGDUMP
 351
 352 void KeychainPromptAclSubject::debugDump() const
 353 {
 354         Debug::dump("KeychainPrompt:%s(%s)",
 355                 description.c_str(),
 356                 (selector.flags & CSSM_ACL_KEYCHAIN_PROMPT_REQUIRE_PASSPHRASE) ? "passphrase" : "standard");
 357 }
 358
 359 #endif //DEBUGDUMP
 360
 361
 362 uint32_t KeychainPromptAclSubject::getPromptAttempts() {
 363     if (csr_check(CSR_ALLOW_APPLE_INTERNAL)) {
 364         // Not an internal install; don't answer
 365         return 0;
 366     } else {
 367         return KeychainPromptAclSubject::promptsValidated;
 368     }
 369 }
 370
 371 void KeychainPromptAclSubject::addPromptAttempt() {
 372     promptsValidated++;
 373 }