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
  55 #include <Security/AuthorizationTagsPriv.h>
  56
  57 #define ACCEPT_LEGACY_FORM 1
  58
  59
  60 //
  61 // The default for the selector structure.
  62 //
  63 CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR KeychainPromptAclSubject::defaultSelector = {
  64         CSSM_ACL_KEYCHAIN_PROMPT_CURRENT_VERSION,       // version
  65         0                                                                                       // flags
  66 };
  67
  68
  69 //
  70 // If we have a KeychainPromptAclSubject, we want KeychainMigrator to have
  71 // access even if we don't have the "pop ui" credential. Do the code signing
  72 // check first, then process this ACL as normal.
  73 //
  74 bool KeychainPromptAclSubject::validates(const AclValidationContext &ctx) const
  75 {
  76     Process &process = Server::process();
  77     if (process.checkAppleSigned() && process.hasEntitlement(migrationEntitlement)) {
  78         Syslog::info("bypassing keychain prompt for keychain migrator");
  79         secdebug("kcacl", "bypassing keychain prompt for keychain migrator");
  80         return true;   // migrator client -> automatic win
  81     }
  82
  83     return SimpleAclSubject::validates(ctx);
  84 }
  85
  86
  87 //
  88 // Validate a credential set against this subject.
  89 //
  90 bool KeychainPromptAclSubject::validates(const AclValidationContext &context,
  91     const TypedList &sample) const
  92 {
  93         return validateExplicitly(context, ^{
  94                 if (SecurityServerEnvironment *env = context.environment<SecurityServerEnvironment>()) {
  95                         Process& process = env->database->process();
  96                         StLock<Mutex> _(process);
  97                         RefPointer<OSXCode> clientXCode = new OSXCodeWrap(process.currentGuest());
  98                         RefPointer<AclSubject> subject = new CodeSignatureAclSubject(OSXVerifier(clientXCode));
  99                         if (SecurityServerAcl::addToStandardACL(context, subject)) {
 100                 if(env->database->dbVersion() >= CommonBlob::version_partition) {
 101                     env->acl.addClientPartitionID(process);
 102                 }
 103                         }
 104                 }
 105         });
 106 }
 107
 108 bool KeychainPromptAclSubject::validateExplicitly(const AclValidationContext &context, void (^alwaysAllow)()) const
 109 {
 110     if (SecurityServerEnvironment *env = context.environment<SecurityServerEnvironment>()) {
 111                 Process &process = Server::process();
 112                 secdebug("kcacl", "Keychain query for process %d (UID %d)", process.pid(), process.uid());
 113
 114                 // assemble the effective validity mode mask
 115                 uint32_t mode = Maker::defaultMode;
 116                 const uint16_t &flags = selector.flags;
 117                 if (flags & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED_ACT)
 118                         mode = (mode & ~CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED) | (flags & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED);
 119                 if (flags & CSSM_ACL_KEYCHAIN_PROMPT_INVALID_ACT)
 120                         mode = (mode & ~CSSM_ACL_KEYCHAIN_PROMPT_INVALID) | (flags & CSSM_ACL_KEYCHAIN_PROMPT_INVALID);
 121
 122                 // determine signed/validity status of client, without reference to any particular Code Requirement
 123                 SecCodeRef clientCode = NULL;
 124                 OSStatus validation = errSecCSStaticCodeNotFound;
 125                 {
 126                         StLock<Mutex> _(process);
 127                         Server::active().longTermActivity();
 128                         clientCode = process.currentGuest();
 129                         if (clientCode) {
 130                                 validation = SecCodeCheckValidity(clientCode, kSecCSDefaultFlags, NULL);
 131             }
 132
 133                         switch (validation)
 134                         {
 135                                 case noErr:                                                     // client is signed and valid
 136                                 {
 137                                         secdebug("kcacl", "client is valid, proceeding");
 138                     // This should almost always be handled by the check in KeychainPromptAclSubject::validate, but check again just in case
 139                     if (process.checkAppleSigned() && process.hasEntitlement(migrationEntitlement)) {
 140                         Syslog::info("bypassing keychain prompt for keychain migrator");
 141                         secdebug("kcacl", "bypassing keychain prompt for keychain migrator");
 142                                                 return true;    // migrator client -> automatic win
 143                     }
 144                                 }
 145                                 break;
 146
 147                                 case errSecCSUnsigned:
 148                                 {                       // client is not signed
 149                                         if (!(mode & CSSM_ACL_KEYCHAIN_PROMPT_UNSIGNED)) {
 150                         Syslog::info("supressing keychain prompt for unsigned client %s(%d)", process.getPath().c_str(), process.pid());
 151                         secdebug("kcacl", "supressing keychain prompt for unsigned client %s(%d)", process.getPath().c_str(), process.pid());
 152                                                 return false;
 153                                         }
 154                                 }
 155                                 break;
 156
 157                                 case errSecCSSignatureFailed:           // client signed but signature is broken
 158                                 case errSecCSGuestInvalid:                      // client signed but dynamically invalid
 159                                 case errSecCSStaticCodeNotFound:        // client not on disk (or unreadable)
 160                                 {
 161                                         if (!(mode & CSSM_ACL_KEYCHAIN_PROMPT_INVALID)) {
 162                                                 secdebug("kcacl", "client is invalid, suppressing prompt");
 163                                                 Syslog::info("suppressing keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 164                         secdebug("kcacl", "suppressing keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 165                                                 return false;
 166                                         }
 167                                         Syslog::info("attempting keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 168                     secdebug("kcacl", "attempting keychain prompt for invalidly signed client %s(%d)", process.getPath().c_str(), process.pid());
 169                                 }
 170                                 break;
 171
 172                                 default:                                                        // something else went wrong
 173                     Syslog::info("suppressing keychain prompt %s(%d); code signing check failed rc=%d", process.getPath().c_str(), process.pid(),  (int32_t) validation);
 174                     secdebug("kcacl", "suppressing keychain prompt %s(%d); code signing check failed rc=%d", process.getPath().c_str(), process.pid(),  (int32_t) validation);
 175                                         return false;
 176                         }
 177                 }
 178
 179                 // At this point, we're committed to try to Pop The Question. Now, how?
 180         Syslog::info("displaying keychain prompt for %s(%d)", process.getPath().c_str(), process.pid());
 181         secdebug("kcacl", "displaying keychain prompt for %s(%d)", process.getPath().c_str(), process.pid());
 182
 183                 // does the user need to type in the passphrase?
 184         const Database *db = env->database;
 185         bool needPassphrase = db && (selector.flags & CSSM_ACL_KEYCHAIN_PROMPT_REQUIRE_PASSPHRASE);
 186
 187                 // an application (i.e. Keychain Access.app :-) can force this option
 188                 if (clientCode && validation == noErr) {
 189                         StLock<Mutex> _(process);
 190                         CFRef<CFDictionaryRef> dict;
 191                         if (SecCodeCopySigningInformation(clientCode, kSecCSDefaultFlags, &dict.aref()) == noErr)
 192                                 if (CFDictionaryRef info = CFDictionaryRef(CFDictionaryGetValue(dict, kSecCodeInfoPList)))
 193                                         needPassphrase |=
 194                                                 (CFDictionaryGetValue(info, CFSTR("SecForcePassphrasePrompt")) != NULL);
 195                 }
 196
 197                 // pop The Question
 198                 if (db && db->belongsToSystem() && !hasAuthorizedForSystemKeychain()) {
 199                         QueryKeychainAuth query;
 200                         query.inferHints(Server::process());
 201                         if (query(db ? db->dbName() : NULL, description.c_str(), context.authorization(), NULL) != SecurityAgent::noReason)
 202                                 return false;
 203                         return true;
 204                 } else {
 205                         QueryKeychainUse query(needPassphrase, db);
 206                         query.inferHints(Server::process());
 207                         query.addHint(AGENT_HINT_CLIENT_VALIDITY, &validation, sizeof(validation));
 208                         if (query.queryUser(db ? db->dbName() : NULL,
 209                                 description.c_str(), context.authorization()) != SecurityAgent::noReason)
 210                                 return false;
 211
 212                         // process an "always allow..." response
 213                         if (query.remember && clientCode) {
 214                                 alwaysAllow();
 215                         }
 216
 217                         // finally, return the actual user response
 218                         return query.allow;
 219                 }
 220     }
 221         return false;        // default to deny without prejudice
 222 }
 223
 224
 225 //
 226 // Make a copy of this subject in CSSM_LIST form
 227 //
 228 CssmList KeychainPromptAclSubject::toList(Allocator &alloc) const
 229 {
 230         // always issue new (non-legacy) form
 231         return TypedList(alloc, CSSM_ACL_SUBJECT_TYPE_KEYCHAIN_PROMPT,
 232                 new(alloc) ListElement(alloc, CssmData::wrap(selector)),
 233         new(alloc) ListElement(alloc, description));
 234 }
 235
 236 //
 237 // Has the caller recently authorized in such a way as to render unnecessary
 238 // the usual QueryKeychainAuth dialog?  (The right is specific to Keychain
 239 // Access' way of editing a system keychain.)
 240 //
 241 bool KeychainPromptAclSubject::hasAuthorizedForSystemKeychain() const
 242 {
 243     string rightString = "system.keychain.modify";
 244     return Server::session().isRightAuthorized(rightString, Server::connection(), false/*no UI*/);
 245 }
 246
 247
 248
 249 //
 250 // Create a KeychainPromptAclSubject
 251 //
 252 uint32_t KeychainPromptAclSubject::Maker::defaultMode;
 253
 254 KeychainPromptAclSubject *KeychainPromptAclSubject::Maker::make(const TypedList &list) const
 255 {
 256         switch (list.length()) {
 257 #if ACCEPT_LEGACY_FORM
 258         case 2: // legacy case: just description
 259                 {
 260                         ListElement *params[1];
 261                         crack(list, 1, params, CSSM_LIST_ELEMENT_DATUM);
 262                         return new KeychainPromptAclSubject(*params[0], defaultSelector);
 263                 }
 264 #endif //ACCEPT_LEGACY_FORM
 265         case 3: // standard case: selector + description
 266                 {
 267                         ListElement *params[2];
 268                         crack(list, 2, params, CSSM_LIST_ELEMENT_DATUM, CSSM_LIST_ELEMENT_DATUM);
 269                         return new KeychainPromptAclSubject(*params[1],
 270                                 *params[0]->data().interpretedAs<CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR>(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE));
 271                 }
 272         default:
 273                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 274         }
 275 }
 276
 277 KeychainPromptAclSubject *KeychainPromptAclSubject::Maker::make(Version version,
 278         Reader &pub, Reader &) const
 279 {
 280         CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR selector;
 281         const char *description;
 282         switch (version) {
 283         case pumaVersion:
 284                 selector = defaultSelector;
 285                 pub(description);
 286                 break;
 287         case jaguarVersion:
 288                 pub(selector);
 289                 selector.version = n2h(selector.version);
 290                 selector.flags = n2h(selector.flags);
 291                 pub(description);
 292                 break;
 293         default:
 294                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 295         }
 296         return new KeychainPromptAclSubject(description, selector);
 297 }
 298
 299 KeychainPromptAclSubject::KeychainPromptAclSubject(string descr,
 300         const CSSM_ACL_KEYCHAIN_PROMPT_SELECTOR &sel)
 301         : SimpleAclSubject(CSSM_ACL_SUBJECT_TYPE_KEYCHAIN_PROMPT),
 302         selector(sel), description(descr)
 303 {
 304         // check selector version
 305         if (selector.version != CSSM_ACL_KEYCHAIN_PROMPT_CURRENT_VERSION)
 306                 CssmError::throwMe(CSSM_ERRCODE_INVALID_ACL_SUBJECT_VALUE);
 307
 308         // always use the latest binary version
 309         version(currentVersion);
 310 }
 311
 312
 313 //
 314 // Export the subject to a memory blob
 315 //
 316 void KeychainPromptAclSubject::exportBlob(Writer::Counter &pub, Writer::Counter &priv)
 317 {
 318         if (version() != 0) {
 319                 selector.version = h2n (selector.version);
 320                 selector.flags = h2n (selector.flags);
 321                 pub(selector);
 322         }
 323
 324     pub.insert(description.size() + 1);
 325 }
 326
 327 void KeychainPromptAclSubject::exportBlob(Writer &pub, Writer &priv)
 328 {
 329         if (version() != 0) {
 330                 selector.version = h2n (selector.version);
 331                 selector.flags = h2n (selector.flags);
 332                 pub(selector);
 333         }
 334     pub(description.c_str());
 335 }
 336
 337
 338 #ifdef DEBUGDUMP
 339
 340 void KeychainPromptAclSubject::debugDump() const
 341 {
 342         Debug::dump("KeychainPrompt:%s(%s)",
 343                 description.c_str(),
 344                 (selector.flags & CSSM_ACL_KEYCHAIN_PROMPT_REQUIRE_PASSPHRASE) ? "passphrase" : "standard");
 345 }
 346
 347 #endif //DEBUGDUMP