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         return validateExplicitly(context, ^{
 104                 if (SecurityServerEnvironment *env = context.environment<SecurityServerEnvironment>()) {
 105             Process& process = Server::process();
 106                         StLock<Mutex> _(process);
 107                         RefPointer<AclSubject> subject = process.copyAclSubject();
 108                         if (SecurityServerAcl::addToStandardACL(context, subject)) {
 109                 if(env->database && env->database->dbVersion() >= CommonBlob::version_partition) {
 110                     env->acl.addClientPartitionID(process);
 111                 }
 112                         }
 113                 }
 114         });
 115 }
 116
 117 bool KeychainPromptAclSubject::validateExplicitly(const AclValidationContext &context, void (^alwaysAllow)()) const
 118 {
 119     if (SecurityServerEnvironment *env = context.environment<SecurityServerEnvironment>()) {
 120                 Process &process = Server::process();
 121                 secnotice("kcacl", "Keychain query for process %d (UID %d)", process.pid(), process.uid());
 122
 123                 // assemble the effective validity mode mask
 124                 uint32_t mode = Maker::defaultMode;
 125                 const uint16_t &flags = selector.flags;
 126                 if (flags & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED_ACT)
 127                         mode = (mode & ~CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED) | (flags & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED);
 128                 if (flags & CSSM_ACL_KEYCHAIN_PROMPT_INVALID_ACT)
 129                         mode = (mode & ~CSSM_ACL_KEYCHAIN_PROMPT_INVALID) | (flags & CSSM_ACL_KEYCHAIN_PROMPT_INVALID);
 130
 131                 // determine signed/validity status of client, without reference to any particular Code Requirement
 132                 OSStatus validation = errSecCSStaticCodeNotFound;
 133                 {
 134                         StLock<Mutex> _(process);
 135                         Server::active().longTermActivity();
 136
 137                         validation = process.checkValidity(kSecCSDefaultFlags, NULL);
 138
 139                         switch (validation)
 140                         {
 141                                 case noErr:                                                     // client is signed and valid
 142                                 {
 143                                         secnotice("kcacl", "client is valid, proceeding");
 144                     // This should almost always be handled by the check in KeychainPromptAclSubject::validate, but check again just in case
 145                     if (process.checkAppleSigned() && process.hasEntitlement(migrationEntitlement)) {
 146                         Syslog::info("bypassing keychain prompt for keychain migrator");
 147                         secnotice("kcacl", "bypassing keychain prompt for keychain migrator");
 148                                                 return true;    // migrator client -> automatic win
 149                     }
 150                                 }
 151                                 break;
 152
 153                                 case errSecCSUnsigned:
 154                                 {                       // client is not signed
 155                                         if (!(mode & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED)) {
 156                         Syslog::info("supressing keychain prompt for unsigned client %s(%d)", process.getPath().c_str(), process.pid());
 157                         secnotice("kcacl", "supressing keychain prompt for unsigned client %s(%d)", process.getPath().c_str(), process.pid());
 158                                                 return false;
 159                                         }
 160                                 }
 161                                 break;
 162
 163                                 case errSecCSSignatureFailed:           // client signed but signature is broken
 164                                 case errSecCSGuestInvalid:                      // client signed but dynamically invalid
 165                                 case errSecCSStaticCodeNotFound:        // client not on disk (or unreadable)
 166                                 {
 167                                         if (!(mode & CSSM_ACL_KEYCHAIN_PROMPT_INVALID)) {
 168                                                 secnotice("kcacl", "client is invalid, suppressing prompt");
 169                                                 Syslog::info("suppressing keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 170                         secnotice("kcacl", "suppressing keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 171                                                 return false;
 172                                         }
 173                                         Syslog::info("attempting keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 174                     secnotice("kcacl", "attempting keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 175                                 }
 176                                 break;
 177
 178                                 default:                                                        // something else went wrong
 179                     Syslog::info("suppressing keychain prompt %s(%d); code signing check failed rc=%d", process.getPath().c_str(), process.pid(),  (int32_t) validation);
 180                     secnotice("kcacl", "suppressing keychain prompt %s(%d); code signing check failed rc=%d", process.getPath().c_str(), process.pid(),  (int32_t) validation);
 181                                         return false;
 182                         }
 183                 }
 184
 185                 // At this point, we're committed to try to Pop The Question. Now, how?
 186         Syslog::info("displaying keychain prompt for %s(%d)", process.getPath().c_str(), process.pid());
 187         secnotice("kcacl", "displaying keychain prompt for %s(%d)", process.getPath().c_str(), process.pid());
 188
 189                 // does the user need to type in the passphrase?
 190         const Database *db = env->database;
 191         bool needPassphrase = db && (selector.flags & CSSM_ACL_KEYCHAIN_PROMPT_REQUIRE_PASSPHRASE);
 192
 193                 // an application (i.e. Keychain Access.app :-) can force this option
 194                 if (validation == noErr) {
 195                         StLock<Mutex> _(process);
 196                         CFRef<CFDictionaryRef> dict;
 197                         if (process.copySigningInfo(kSecCSDefaultFlags, &dict.aref()) == noErr)
 198                                 if (CFDictionaryRef info = CFDictionaryRef(CFDictionaryGetValue(dict, kSecCodeInfoPList)))
 199                                         needPassphrase |=
 200                                                 (CFDictionaryGetValue(info, CFSTR("SecForcePassphrasePrompt")) != NULL);
 201                 }
 202
 203                 // pop The Question
 204                 if (db && db->belongsToSystem() && !hasAuthorizedForSystemKeychain()) {
 205                         QueryKeychainAuth query;
 206                         query.inferHints(Server::process());
 207                         if (query(db ? db->dbName() : NULL, description.c_str(), context.authorization(), NULL) != SecurityAgent::noReason)
 208                                 return false;
 209                         return true;
 210                 } else {
 211                         QueryKeychainUse query(needPassphrase, db);
 212                         query.inferHints(Server::process());
 213                         query.addHint(AGENT_HINT_CLIENT_VALIDITY, &validation, sizeof(validation));
 214                         if (query.queryUser(db ? db->dbName() : NULL,
 215                                 description.c_str(), context.authorization()) != SecurityAgent::noReason)
 216                                 return false;
 217
 218                         // process an "always allow..." response
 219                         if (query.remember && validation != errSecCSStaticCodeNotFound) {
 220                                 alwaysAllow();
 221                         }
 222
 223                         // finally, return the actual user response
 224                         return query.allow;
 225                 }
 226     }
 227         return false;        // default to deny without prejudice
 228 }
 229
 230
 231 //
 232 // Make a copy of this subject in CSSM_LIST form
 233 //
 234 CssmList KeychainPromptAclSubject::toList(Allocator &alloc) const
 235 {
 236         // always issue new (non-legacy) form
 237         return TypedList(alloc, CSSM_ACL_SUBJECT_TYPE_KEYCHAIN_PROMPT,
 238                 new(alloc) ListElement(alloc, CssmData::wrap(selector)),
 239         new(alloc) ListElement(alloc, description));
 240 }
 241
 242 //
 243 // Has the caller recently authorized in such a way as to render unnecessary
 244 // the usual QueryKeychainAuth dialog?  (The right is specific to Keychain
 245 // Access' way of editing a system keychain.)
 246 //
 247 bool KeychainPromptAclSubject::hasAuthorizedForSystemKeychain() const
 248 {
 249 //      string rightString = "system.keychain.modify";
 250 //      return Server::session().isRightAuthorized(rightString, Server::connection(), false/*no UI*/);
 251         return false;
 252 }
 253
 254
 255
 256 //
 257 // Create a KeychainPromptAclSubject
 258 //
 259 uint32_t KeychainPromptAclSubject::Maker::defaultMode;
 260
 261 KeychainPromptAclSubject *KeychainPromptAclSubject::Maker::make(const TypedList &list) const
 262 {
 263         switch (list.length()) {
 264 #if ACCEPT_LEGACY_FORM
 265         case 2: // legacy case: just description
 266                 {
 267                         ListElement *params[1];
 268                         crack(list, 1, params, CSSM_LIST_ELEMENT_DATUM);
 269                         return new KeychainPromptAclSubject(*params[0], defaultSelector);
 270                 }
 271 #endif //ACCEPT_LEGACY_FORM
 272         case 3: // standard case: selector + description
 273                 {
 274                         ListElement *params[2];
 275                         crack(list, 2, params, CSSM_LIST_ELEMENT_DATUM, CSSM_LIST_ELEMENT_DATUM);
 276                         return new KeychainPromptAclSubject(*params[1],
 277                                 *params[0]->data().interpretedAs<CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR>(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE));
 278                 }
 279         default:
 280                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 281         }
 282 }
 283
 284 KeychainPromptAclSubject *KeychainPromptAclSubject::Maker::make(Version version,
 285         Reader &pub, Reader &) const
 286 {
 287         CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR selector;
 288         const char *description;
 289         switch (version) {
 290         case pumaVersion:
 291                 selector = defaultSelector;
 292                 pub(description);
 293                 break;
 294         case jaguarVersion:
 295                 pub(selector);
 296                 selector.version = n2h(selector.version);
 297                 selector.flags = n2h(selector.flags);
 298                 pub(description);
 299                 break;
 300         default:
 301                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 302         }
 303         return new KeychainPromptAclSubject(description, selector);
 304 }
 305
 306 KeychainPromptAclSubject::KeychainPromptAclSubject(string descr,
 307         const CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR &sel)
 308         : SimpleAclSubject(CSSM_ACL_SUBJECT_TYPE_KEYCHAIN_PROMPT),
 309         selector(sel), description(descr)
 310 {
 311         // check selector version
 312         if (selector.version != CSSM_ACL_KEYCHAIN_PROMPT_CURRENT_VERSION)
 313                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 314
 315         // always use the latest binary version
 316         version(currentVersion);
 317 }
 318
 319
 320 //
 321 // Export the subject to a memory blob
 322 //
 323 void KeychainPromptAclSubject::exportBlob(Writer::Counter &pub, Writer::Counter &priv)
 324 {
 325         if (version() != 0) {
 326                 selector.version = h2n (selector.version);
 327                 selector.flags = h2n (selector.flags);
 328                 pub(selector);
 329         }
 330
 331     pub.insert(description.size() + 1);
 332 }
 333
 334 void KeychainPromptAclSubject::exportBlob(Writer &pub, Writer &priv)
 335 {
 336         if (version() != 0) {
 337                 selector.version = h2n (selector.version);
 338                 selector.flags = h2n (selector.flags);
 339                 pub(selector);
 340         }
 341     pub(description.c_str());
 342 }
 343
 344
 345 #ifdef DEBUGDUMP
 346
 347 void KeychainPromptAclSubject::debugDump() const
 348 {
 349         Debug::dump("KeychainPrompt:%s(%s)",
 350                 description.c_str(),
 351                 (selector.flags & CSSM_ACL_KEYCHAIN_PROMPT_REQUIRE_PASSPHRASE) ? "passphrase" : "standard");
 352 }
 353
 354 #endif //DEBUGDUMP
 355
 356
 357 uint32_t KeychainPromptAclSubject::getPromptAttempts() {
 358     if (csr_check(CSR_ALLOW_APPLE_INTERNAL)) {
 359         // Not an internal install; don't answer
 360         return 0;
 361     } else {
 362         return KeychainPromptAclSubject::promptsValidated;
 363     }
 364 }
 365
 366 void KeychainPromptAclSubject::addPromptAttempt() {
 367     promptsValidated++;
 368 }