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