OSX/sec/Security/SecItemBackup.c

   1 /*
   2  * Copyright (c) 2015 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
  24
  25 /*
  26  * SecItemBackup.c -  Client side backup interfaces and support code
  27  */
  28
  29 #include <Security/SecItemBackup.h>
  30
  31 #include <Security/SecItemPriv.h>
  32 #include <Security/SecuritydXPC.h>
  33 #include <Security/SecFramework.h>
  34 #include "keychain/securityd/SecItemServer.h"
  35 #include <ipc/securityd_client.h>
  36 #include "keychain/SecureObjectSync/SOSBackupEvent.h"
  37 #include <Security/SecureObjectSync/SOSCloudCircle.h>
  38 #include <Security/SecureObjectSync/SOSViews.h>
  39 #include <corecrypto/ccsha1.h>
  40 #include <utilities/SecCFError.h>
  41 #include <utilities/SecCFRelease.h>
  42 #include <utilities/SecCFCCWrappers.h>
  43 #include <utilities/array_size.h>
  44 #include <utilities/der_plist.h>
  45 #include <utilities/der_plist_internal.h>
  46 #include <AssertMacros.h>
  47 #include <os/activity.h>
  48 #include <notify.h>
  49
  50 #include <sys/stat.h>
  51
  52 static CFDataRef client_data_data_bool_to_data_error_request(enum SecXPCOperation op, SecurityClient *client, CFDataRef keybag, CFDataRef passcode, bool emcs, CFErrorRef *error) {
  53     __block CFDataRef result = NULL;
  54     securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
  55         return SecXPCDictionarySetDataOptional(message, kSecXPCKeyKeybag, keybag, error)
  56         && SecXPCDictionarySetDataOptional(message, kSecXPCKeyUserPassword, passcode, error)
  57         && SecXPCDictionarySetBool(message, kSecXPCKeyEMCSBackup, emcs, NULL);
  58     }, ^bool(xpc_object_t response, CFErrorRef *error) {
  59         return (result = SecXPCDictionaryCopyData(response, kSecXPCKeyResult, error));
  60     });
  61     return result;
  62 }
  63
  64 static bool data_client_data_data_to_error_request(enum SecXPCOperation op, CFDataRef backup, SecurityClient *client, CFDataRef keybag, CFDataRef passcode, CFErrorRef *error) {
  65     return securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
  66         return SecXPCDictionarySetData(message, kSecXPCKeyBackup, backup, error)
  67         && SecXPCDictionarySetData(message, kSecXPCKeyKeybag, keybag, error)
  68         && SecXPCDictionarySetDataOptional(message, kSecXPCKeyUserPassword, passcode, error);
  69     } , NULL);
  70 }
  71
  72 static bool dict_data_data_to_error_request(enum SecXPCOperation op, CFDictionaryRef backup, CFDataRef keybag, CFDataRef passcode, CFErrorRef *error) {
  73     return securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
  74         return SecXPCDictionarySetPList(message, kSecXPCKeyBackup, backup, error)
  75         && SecXPCDictionarySetData(message, kSecXPCKeyKeybag, keybag, error)
  76         && SecXPCDictionarySetDataOptional(message, kSecXPCKeyUserPassword, passcode, error);
  77     } , NULL);
  78 }
  79
  80 static CFDictionaryRef data_data_dict_to_dict_error_request(enum SecXPCOperation op, CFDictionaryRef backup, CFDataRef keybag, CFDataRef passcode, CFErrorRef *error) {
  81     __block CFDictionaryRef dict = NULL;
  82     securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
  83         return SecXPCDictionarySetPListOptional(message, kSecXPCKeyBackup, backup, error)
  84         && SecXPCDictionarySetData(message, kSecXPCKeyKeybag, keybag, error)
  85         && SecXPCDictionarySetDataOptional(message, kSecXPCKeyUserPassword, passcode, error);
  86     }, ^bool(xpc_object_t response, CFErrorRef *error) {
  87         return (dict = SecXPCDictionaryCopyDictionary(response, kSecXPCKeyResult, error));
  88     });
  89     return dict;
  90 }
  91
  92 static int string_to_fd_error_request(enum SecXPCOperation op, CFStringRef backupName, CFErrorRef *error) {
  93     __block int fd = -1;
  94     securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
  95         return SecXPCDictionarySetString(message, kSecXPCKeyBackup, backupName, error);
  96     }, ^bool(xpc_object_t response, CFErrorRef *error) {
  97         fd = SecXPCDictionaryDupFileDescriptor(response, kSecXPCKeyResult, error);
  98         return true;
  99     });
 100     return fd;
 101 }
 102
 103 static bool string_data_data_to_bool_error_request(enum SecXPCOperation op, CFStringRef backupName, CFDataRef keybagDigest, CFDataRef manifest, CFErrorRef *error)
 104 {
 105     return securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
 106         return SecXPCDictionarySetString(message, kSecXPCKeyBackup, backupName, error) &&
 107                 SecXPCDictionarySetDataOptional(message, kSecXPCKeyKeybag, keybagDigest, error) &&
 108                 SecXPCDictionarySetDataOptional(message, kSecXPCData, manifest, error);
 109     }, ^bool(xpc_object_t response, __unused CFErrorRef *error) {
 110         return xpc_dictionary_get_bool(response, kSecXPCKeyResult);
 111     });
 112 }
 113
 114 static bool string_string_data_data_data_to_bool_error_request(enum SecXPCOperation op, CFStringRef backupName, CFStringRef peerID, CFDataRef keybag, CFDataRef secret, CFDataRef backup, CFErrorRef *error)
 115 {
 116     return securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
 117         return SecXPCDictionarySetString(message, kSecXPCKeyBackup, backupName, error) &&
 118         SecXPCDictionarySetStringOptional(message, kSecXPCKeyDigest, peerID, error) &&
 119         SecXPCDictionarySetData(message, kSecXPCKeyKeybag, keybag, error) &&
 120         SecXPCDictionarySetData(message, kSecXPCKeyUserPassword, secret, error) &&
 121         SecXPCDictionarySetData(message, kSecXPCData, backup, error);
 122     }, ^bool(xpc_object_t response, __unused CFErrorRef *error) {
 123         return xpc_dictionary_get_bool(response, kSecXPCKeyResult);
 124     });
 125 }
 126
 127 static CFArrayRef to_array_error_request(enum SecXPCOperation op, CFErrorRef *error)
 128 {
 129     __block CFArrayRef result = NULL;
 130     securityd_send_sync_and_do(op, error, ^bool(xpc_object_t message, CFErrorRef *error) {
 131         return true;
 132     }, ^bool(xpc_object_t response, CFErrorRef *error) {
 133         return result = SecXPCDictionaryCopyArray(response, kSecXPCKeyResult, error);
 134     });
 135     return result;
 136 }
 137
 138 // XPC calls
 139
 140 static int SecItemBackupHandoffFD(CFStringRef backupName, CFErrorRef *error) {
 141     __block int fileDesc = -1;
 142     os_activity_initiate("SecItemBackupHandoffFD", OS_ACTIVITY_FLAG_DEFAULT, ^{
 143         fileDesc = SECURITYD_XPC(sec_item_backup_handoff_fd, string_to_fd_error_request, backupName, error);
 144     });
 145     return fileDesc;
 146 }
 147
 148 CFDataRef _SecKeychainCopyOTABackup(void) {
 149     __block CFDataRef result;
 150     os_activity_initiate("_SecKeychainCopyOTABackup", OS_ACTIVITY_FLAG_DEFAULT, ^{
 151         result = SECURITYD_XPC(sec_keychain_backup, client_data_data_bool_to_data_error_request, SecSecurityClientGet(), NULL, NULL, false, NULL);
 152     });
 153     return result;
 154 }
 155
 156 CFDataRef _SecKeychainCopyBackup(CFDataRef backupKeybag, CFDataRef password) {
 157     __block CFDataRef result;
 158     os_activity_initiate("_SecKeychainCopyBackup", OS_ACTIVITY_FLAG_DEFAULT, ^{
 159         result = SECURITYD_XPC(sec_keychain_backup, client_data_data_bool_to_data_error_request, SecSecurityClientGet(), backupKeybag, password, false, NULL);
 160     });
 161     return result;
 162 }
 163
 164 CFDataRef _SecKeychainCopyEMCSBackup(CFDataRef backupKeybag) {
 165     __block CFDataRef result;
 166     os_activity_initiate("_SecKeychainCopyEMCSBackup", OS_ACTIVITY_FLAG_DEFAULT, ^{
 167         result = SECURITYD_XPC(sec_keychain_backup, client_data_data_bool_to_data_error_request, SecSecurityClientGet(), backupKeybag, NULL, true, NULL);
 168     });
 169     return result;
 170 }
 171
 172 bool _SecKeychainWriteBackupToFileDescriptor(CFDataRef backupKeybag, CFDataRef password, int fd, CFErrorRef *error) {
 173     __block bool result = false;
 174     os_activity_initiate("_SecKeychainWriteBackupToFile", OS_ACTIVITY_FLAG_DEFAULT, ^{
 175
 176         securityd_send_sync_and_do(sec_keychain_backup_id, error, ^bool(xpc_object_t message, CFErrorRef *error) {
 177             return SecXPCDictionarySetDataOptional(message, kSecXPCKeyKeybag, backupKeybag, error)
 178                 && SecXPCDictionarySetDataOptional(message, kSecXPCKeyUserPassword, password, error)
 179                 && SecXPCDictionarySetFileDescriptor(message, kSecXPCKeyFileDescriptor, fd, error);
 180         }, ^bool(xpc_object_t response, CFErrorRef *error) {
 181             return (result = SecXPCDictionaryGetBool(response, kSecXPCKeyResult, error));
 182         });
 183     });
 184     return result;
 185 }
 186
 187 bool
 188 _SecKeychainRestoreBackupFromFileDescriptor(int fd, CFDataRef backupKeybag, CFDataRef password, CFErrorRef *error)
 189 {
 190     __block bool result;
 191     os_activity_initiate("_SecKeychainRestoreBackup", OS_ACTIVITY_FLAG_DEFAULT, ^{
 192         securityd_send_sync_and_do(sec_keychain_restore_id, error, ^bool(xpc_object_t message, CFErrorRef *error) {
 193             return SecXPCDictionarySetFileDescriptor(message, kSecXPCKeyFileDescriptor, fd, error)
 194                 && SecXPCDictionarySetData(message, kSecXPCKeyKeybag, backupKeybag, error)
 195                 && SecXPCDictionarySetDataOptional(message, kSecXPCKeyUserPassword, password, error);
 196         }, ^bool(xpc_object_t response, CFErrorRef *error) {
 197             return (result = SecXPCDictionaryGetBool(response, kSecXPCKeyResult, error));
 198         });
 199     });
 200     return result;
 201 }
 202
 203 /*
 204  * Current promise is that this is low memory usage, so in the current format, ask securityd
 205  * to resolve the item for us.
 206  */
 207
 208 CFStringRef
 209 _SecKeychainCopyKeybagUUIDFromFileDescriptor(int fd, CFErrorRef *error)
 210 {
 211     __block CFStringRef result = NULL;
 212     os_activity_initiate("_SecKeychainCopyKeybagUUID", OS_ACTIVITY_FLAG_DEFAULT, ^{
 213         securityd_send_sync_and_do(sec_keychain_backup_keybag_uuid_id, error, ^bool(xpc_object_t message, CFErrorRef *error) {
 214             return SecXPCDictionarySetFileDescriptor(message, kSecXPCKeyFileDescriptor, fd, error);
 215         }, ^bool(xpc_object_t response, CFErrorRef *error) {
 216             return (result = SecXPCDictionaryCopyString(response, kSecXPCKeyResult, error));
 217         });
 218     });
 219     return result;
 220 }
 221
 222
 223 OSStatus _SecKeychainRestoreBackup(CFDataRef backup, CFDataRef backupKeybag,
 224                                    CFDataRef password) {
 225     __block OSStatus result;
 226     os_activity_initiate("_SecKeychainRestoreBackup", OS_ACTIVITY_FLAG_DEFAULT, ^{
 227         result = SecOSStatusWith(^bool (CFErrorRef *error) {
 228             return SECURITYD_XPC(sec_keychain_restore, data_client_data_data_to_error_request, backup, SecSecurityClientGet(), backupKeybag, password, error);
 229         });
 230     });
 231     return result;
 232 }
 233
 234
 235 static int compareDigests(const void *l, const void *r) {
 236     return memcmp(l, r, CCSHA1_OUTPUT_SIZE);
 237 }
 238
 239 CFDataRef SecItemBackupCreateManifest(CFDictionaryRef backup, CFErrorRef *error)
 240 {
 241     CFIndex count = backup ? CFDictionaryGetCount(backup) : 0;
 242     CFMutableDataRef manifest = CFDataCreateMutable(kCFAllocatorDefault, CCSHA1_OUTPUT_SIZE * count);
 243     if (backup) {
 244         CFDictionaryForEach(backup, ^void (const void *key, const void *value) {
 245             if (isDictionary(value)) {
 246                 /* converting key back to binary blob is horrible */
 247                 CFDataRef sha1 = CFDictionaryGetValue(value, kSecItemBackupHashKey);
 248                 if (isData(sha1) && CFDataGetLength(sha1) == CCSHA1_OUTPUT_SIZE) {
 249                     CFDataAppend(manifest, sha1);
 250                 } else {
 251                     CFStringRef sha1Hex = CFDataCopyHexString(sha1);
 252                     secerror("bad hash %@ in backup", sha1Hex);
 253                     CFReleaseSafe(sha1Hex);
 254                     // TODO: Drop this key from dictionary (outside the loop)
 255                 }
 256             }
 257         });
 258         qsort(CFDataGetMutableBytePtr(manifest), CFDataGetLength(manifest) / CCSHA1_OUTPUT_SIZE, CCSHA1_OUTPUT_SIZE, compareDigests);
 259     }
 260     return manifest;
 261 }
 262
 263 OSStatus _SecKeychainBackupSyncable(CFDataRef keybag, CFDataRef password, CFDictionaryRef backup_in, CFDictionaryRef *backup_out)
 264 {
 265     return SecOSStatusWith(^bool (CFErrorRef *error) {
 266         *backup_out = SECURITYD_XPC(sec_keychain_backup_syncable, data_data_dict_to_dict_error_request, backup_in, keybag, password, error);
 267         return *backup_out != NULL;
 268     });
 269 }
 270
 271 OSStatus _SecKeychainRestoreSyncable(CFDataRef keybag, CFDataRef password, CFDictionaryRef backup_in)
 272 {
 273     __block OSStatus result;
 274     os_activity_initiate("_SecKeychainRestoreSyncable", OS_ACTIVITY_FLAG_DEFAULT, ^{
 275         result = SecOSStatusWith(^bool (CFErrorRef *error) {
 276             return SECURITYD_XPC(sec_keychain_restore_syncable, dict_data_data_to_error_request, backup_in, keybag, password, error);
 277         });
 278     });
 279     return result;
 280 }
 281
 282 // Client code
 283
 284 static bool SecKeychainWithBackupFile(CFStringRef backupName, CFErrorRef *error, void(^with)(FILE *bufile)) {
 285     int fd = SecItemBackupHandoffFD(backupName, error);
 286     if (fd < 0) {
 287         secdebug("backup", "SecItemBackupHandoffFD returned %d", fd);
 288         return false;
 289     }
 290
 291     // Rewind file to start
 292     if (lseek(fd, 0, SEEK_SET)) {
 293         secdebug("backup", "Could not seek in fd %d for %@", fd, backupName);
 294         return SecCheckErrno(true, error, CFSTR("lseek"));
 295     }
 296
 297     FILE *backup = fdopen(fd, "r");
 298     if (!backup) {
 299         secdebug("backup", "Receiving file for %@ failed, %d", backupName, errno);
 300         SecCheckErrno(!backup, error, CFSTR("fdopen"));
 301         if (close(fd)) {
 302             secdebug("backup", "Encountered error closing file %@: %d", backupName, errno);
 303             SecCheckErrno(true, error, CFSTR("close"));
 304         }
 305         return false;
 306     } else {
 307         struct stat sb;
 308         if (fstat(fd, &sb)) {
 309             secdebug("backup", "Unable to get file metadata for %@, fd %d", backupName, fd);
 310             SecCheckErrno(true, error, CFSTR("fstat"));
 311             if (fclose(backup)) {
 312                 secdebug("backup", "Encountered error closing file %@: %d", backupName, errno);
 313                 SecCheckErrno(true, error, CFSTR("fclose"));
 314             }
 315             return false;
 316         }
 317         secdebug("backup", "Receiving file for %@ with fd %d of size %llu", backupName, fd, sb.st_size);
 318     }
 319
 320     with(backup);
 321     if (fclose(backup)) {
 322         secdebug("backup", "Encountered error %d closing file %@ after backup handler", errno, backupName);
 323         SecCheckErrno(true, error, CFSTR("fclose"));
 324         // read only file and block has its own error handling for IO failure, no need to return false
 325     }
 326     return true;
 327 }
 328
 329 static CFArrayRef SecItemBackupCopyNames(CFErrorRef *error)
 330 {
 331     __block CFArrayRef result;
 332     os_activity_initiate("SecItemBackupCopyNames", OS_ACTIVITY_FLAG_DEFAULT, ^{
 333         result = SECURITYD_XPC(sec_item_backup_copy_names, to_array_error_request, error);
 334     });
 335     return result;
 336 }
 337
 338 bool SecItemBackupWithRegisteredBackups(CFErrorRef *error, void(^backup)(CFStringRef backupName)) {
 339     CFArrayRef backupNames = SecItemBackupCopyNames(error);
 340     if (!backupNames) return false;
 341     CFStringRef name;
 342     CFArrayForEachC(backupNames, name) {
 343         backup(name);
 344     }
 345     CFRelease(backupNames);
 346     return true;
 347 }
 348
 349 static bool SecItemBackupDoResetEventBody(const uint8_t *der, const uint8_t *der_end, CFErrorRef *error, void (^handleEvent)(SecBackupEventType et, CFTypeRef key, CFTypeRef item)) {
 350     size_t sequence_len;
 351     const uint8_t *sequence_body = ccder_decode_len(&sequence_len, der, der_end);
 352     bool ok = sequence_body;
 353     if (ok && sequence_body + sequence_len != der_end) {
 354         // Can't ever happen!
 355         SecError(errSecDecode, error, CFSTR("trailing junk after reset"));
 356         ok = false;
 357     }
 358     if (ok) {
 359         CFDataRef keybag = NULL;
 360         if (sequence_body != der_end) {
 361             size_t keybag_len = 0;
 362             const uint8_t *keybag_start = ccder_decode_tl(CCDER_OCTET_STRING, &keybag_len, sequence_body, der_end);
 363             if (!keybag_start) {
 364                 ok = SecError(errSecDecode, error, CFSTR("failed to decode keybag"));
 365             } else if (keybag_start + keybag_len != der_end) {
 366                 ok = SecError(errSecDecode, error, CFSTR("trailing junk after keybag"));
 367             } else {
 368                 keybag = CFDataCreate(kCFAllocatorDefault, keybag_start, keybag_len);
 369             }
 370         }
 371         handleEvent(kSecBackupEventReset, keybag, NULL);
 372         CFReleaseSafe(keybag);
 373     }
 374
 375     return ok;
 376 }
 377
 378 static bool SecItemBackupDoAddEvent(const uint8_t *der, const uint8_t *der_end, CFErrorRef *error, void (^handleEvent)(SecBackupEventType et, CFTypeRef key, CFTypeRef item)) {
 379     CFDictionaryRef eventDict = NULL;
 380     const uint8_t *der_end_of_dict = der_decode_dictionary(kCFAllocatorDefault, kCFPropertyListImmutable, &eventDict, error, der, der_end);
 381     if (der_end_of_dict && der_end_of_dict != der_end) {
 382         // Can't ever happen!
 383         SecError(errSecDecode, error, CFSTR("trailing junk after add"));
 384         der_end_of_dict = NULL;
 385     }
 386     if (der_end_of_dict) {
 387         CFDataRef hash = CFDictionaryGetValue(eventDict, kSecItemBackupHashKey);
 388         handleEvent(kSecBackupEventAdd, hash, eventDict);
 389     }
 390
 391     CFReleaseSafe(eventDict);
 392     return der_end_of_dict;
 393 }
 394
 395 static bool SecItemBackupDoCompleteEvent(const uint8_t *der, const uint8_t *der_end, CFErrorRef *error, void (^handleEvent)(SecBackupEventType et, CFTypeRef key, CFTypeRef item)) {
 396     uint64_t event_num = 0;
 397     const uint8_t *der_end_of_num = ccder_decode_uint64(&event_num, der, der_end);
 398     if (der_end_of_num && der_end_of_num != der_end) {
 399         // Can't ever happen!
 400         SecError(errSecDecode, error, CFSTR("trailing junk after complete"));
 401         der_end_of_num = NULL;
 402     }
 403     if (der_end_of_num) {
 404         handleEvent(kSecBackupEventComplete, NULL, NULL);
 405     }
 406     return der_end_of_num;
 407 }
 408
 409 static bool SecItemBackupDoDeleteEventBody(const uint8_t *der, const uint8_t *der_end, CFErrorRef *error, void (^handleEvent)(SecBackupEventType et, CFTypeRef key, CFTypeRef item)) {
 410     size_t digest_len = 0;
 411     const uint8_t *digest_start = ccder_decode_len(&digest_len, der, der_end);
 412     if (digest_start && digest_start + digest_len != der_end) {
 413         // Can't ever happen!
 414         SecError(errSecDecode, error, CFSTR("trailing junk after delete"));
 415         digest_start = NULL;
 416     }
 417     if (digest_start) {
 418         CFDataRef hash = CFDataCreate(kCFAllocatorDefault, digest_start, digest_len);
 419         handleEvent(kSecBackupEventRemove, hash, NULL);
 420         CFRelease(hash);
 421     }
 422
 423     return digest_start;
 424 }
 425
 426 static void debugDisplayBackupEventTag(ccder_tag tag) {
 427 #if !defined(NDEBUG)
 428     const char *eventDesc;
 429     switch (tag) {
 430         case CCDER_CONSTRUCTED_SEQUENCE:    eventDesc = "ResetEvent"; break;
 431         case CCDER_CONSTRUCTED_SET:         eventDesc = "AddEvent"; break;
 432         case CCDER_INTEGER:                 eventDesc = "ResetEvent"; break;
 433         case CCDER_OCTET_STRING:            eventDesc = "DeleteEvent"; break;
 434         default:                            eventDesc = "UnknownEvent"; break;
 435     }
 436     secdebug("backup", "processing event %s (tag %08lX)", eventDesc, tag);
 437 #endif
 438 }
 439
 440 static bool SecItemBackupDoEvent(const uint8_t *der, const uint8_t *der_end, CFErrorRef *error, void (^handleEvent)(SecBackupEventType et, CFTypeRef key, CFTypeRef item)) {
 441     ccder_tag tag;
 442     const uint8_t *der_start_of_len = ccder_decode_tag(&tag, der, der_end);
 443     debugDisplayBackupEventTag(tag);
 444     switch (tag) {
 445         case CCDER_CONSTRUCTED_SEQUENCE:
 446             return SecItemBackupDoResetEventBody(der_start_of_len, der_end, error, handleEvent);
 447         case CCDER_CONSTRUCTED_SET:
 448             return SecItemBackupDoAddEvent(der, der_end, error, handleEvent);
 449         case CCDER_INTEGER:
 450             return SecItemBackupDoCompleteEvent(der, der_end, error, handleEvent);
 451         case CCDER_OCTET_STRING:
 452             return SecItemBackupDoDeleteEventBody(der_start_of_len, der_end, error, handleEvent);
 453         default:
 454             return SecError(errSecDecode, error, CFSTR("unsupported event tag: %lu"), tag);
 455     }
 456 }
 457
 458 // TODO: Move to ccder and give better name.
 459 static const uint8_t *ccder_decode_len_unchecked(size_t *lenp, const uint8_t *der, const uint8_t *der_end) {
 460     if (der && der < der_end) {
 461         size_t len = *der++;
 462         if (len < 0x80) {
 463         } else if (len == 0x81) {
 464             if (der_end - der < 1) goto errOut;
 465             len = *der++;
 466         } else if (len == 0x82) {
 467             if (der_end - der < 2) goto errOut;
 468             len = *(der++) << 8;
 469             len += *der++;
 470         } else if (len == 0x83) {
 471             if (der_end - der < 3) goto errOut;
 472             len = *(der++) << 16;
 473             len += *(der++) << 8;
 474             len += *(der++);
 475         } else {
 476             goto errOut;
 477         }
 478         *lenp = len;
 479         return der;
 480     }
 481 errOut:
 482     return NULL;
 483 }
 484
 485 static bool SecKeychainWithBackupFileParse(FILE *backup, CFErrorRef *error, void (^handleEvent)(SecBackupEventType et, CFTypeRef key, CFTypeRef item)) {
 486     __block bool ok = true;
 487     size_t buf_remaining = 0;
 488     const size_t read_ahead = 16;
 489     size_t buf_len = read_ahead;
 490     uint8_t *buf = malloc(buf_len);
 491     for (;;) {
 492         const size_t bytes_read = fread(buf + buf_remaining, 1, read_ahead - buf_remaining, backup);
 493         if (bytes_read <= 0) {
 494             if (!feof(backup))
 495                 ok = SecCheckErrno(true, error, CFSTR("read backup event header"));
 496             else if (!buf_remaining) {
 497                 // Nothing read, nothing in buffer, clean eof.
 498             }
 499             break;
 500         }
 501         const size_t buf_avail = bytes_read + buf_remaining;
 502
 503         const uint8_t *der = buf;
 504         const uint8_t *der_end = der + buf_avail;
 505         ccder_tag tag;
 506         size_t body_len;
 507         der = ccder_decode_tag(&tag, der, der_end);
 508         der = ccder_decode_len_unchecked(&body_len, der, der_end);
 509
 510         if (!der) {
 511             ok = SecError(errSecDecode, error, CFSTR("failed to decode backup event header"));
 512             break;
 513         }
 514
 515         const size_t decoded_len = der - buf;
 516         size_t event_len = decoded_len + body_len;
 517         if (event_len > buf_avail) {
 518             // We need to read the rest of this event, first
 519             // ensure we have enough space.
 520             if (buf_len < event_len) {
 521                 // TODO: Think about a max for buf_len here to prevent attacks.
 522                 uint8_t *new_buf = realloc(buf, event_len);
 523                 if (!new_buf) {
 524                     ok = SecError(errSecAllocate, error, CFSTR("realloc buf failed"));
 525                     break;
 526                 }
 527                 buf = new_buf;
 528                 buf_len = event_len;
 529             }
 530
 531             // Read tail of current event.
 532             const size_t tail_len = fread(buf + buf_avail, 1, event_len - buf_avail, backup);
 533             if (tail_len < event_len - buf_avail) {
 534                 if (!feof(backup)) {
 535                     ok = SecCheckErrno(true, error, CFSTR("failed to read event body"));
 536                 } else {
 537                     ok = SecError(errSecDecode, error, CFSTR("unexpected end of event file %zu of %zu bytes read"), tail_len, event_len - buf_avail);
 538                 }
 539                 break;
 540             }
 541         }
 542
 543         // Adjust der_end to the end of the event.
 544         der_end = buf + event_len;
 545
 546         ok &= SecItemBackupDoEvent(buf, der_end, error, handleEvent);
 547
 548         if (event_len < buf_avail) {
 549             // Shift remaining bytes to start of buffer.
 550             buf_remaining = buf_avail - event_len;
 551             memmove(buf, der_end, buf_remaining);
 552         } else {
 553             buf_remaining = 0;
 554         }
 555     }
 556     free(buf);
 557     return ok;
 558 }
 559
 560 bool SecItemBackupWithChanges(CFStringRef backupName, CFErrorRef *error, void (^handleEvent)(SecBackupEventType et, CFTypeRef key, CFTypeRef item)) {
 561     __block bool ok = true;
 562     __block CFErrorRef localError = NULL;
 563     ok &= SecKeychainWithBackupFile(backupName, &localError, ^(FILE *backup) {
 564         ok &= SecKeychainWithBackupFileParse(backup, &localError, handleEvent);
 565     });
 566     if (!ok) {   // TODO: remove this logging
 567         secdebug("backup", "SecItemBackupWithChanges failed: %@", localError);
 568         handleEvent(kSecBackupEventComplete, NULL, NULL);
 569         CFErrorPropagate(localError, error);
 570     }
 571
 572     return ok;
 573 }
 574
 575 bool SecItemBackupSetConfirmedManifest(CFStringRef backupName, CFDataRef keybagDigest, CFDataRef manifest, CFErrorRef *error) {
 576     __block bool result;
 577     os_activity_initiate("SecItemBackupSetConfirmedManifest", OS_ACTIVITY_FLAG_DEFAULT, ^{
 578         result = SECURITYD_XPC(sec_item_backup_set_confirmed_manifest, string_data_data_to_bool_error_request, backupName, keybagDigest, manifest, error);
 579     });
 580     return result;
 581 }
 582
 583 void SecItemBackupRestore(CFStringRef backupName, CFStringRef peerID, CFDataRef keybag, CFDataRef secret, CFTypeRef backup, void (^completion)(CFErrorRef error)) {
 584     __block CFErrorRef localError = NULL;
 585     os_activity_initiate("SecItemBackupRestore", OS_ACTIVITY_FLAG_DEFAULT, ^{
 586         SECURITYD_XPC(sec_item_backup_restore, string_string_data_data_data_to_bool_error_request, backupName, peerID, keybag, secret, backup, &localError);
 587     });
 588     completion(localError);
 589     CFReleaseSafe(localError);
 590 }
 591
 592 CFDictionaryRef SecItemBackupCopyMatching(CFDataRef keybag, CFDataRef secret, CFDictionaryRef backup, CFDictionaryRef query, CFErrorRef *error) {
 593     SecError(errSecUnimplemented, error, CFSTR("SecItemBackupCopyMatching unimplemented"));
 594     return NULL;
 595 }
 596
 597 bool SecBackupKeybagAdd(CFDataRef passcode, CFDataRef *identifier, CFURLRef *pathinfo, CFErrorRef *error) {
 598     __block bool result = false;
 599     os_activity_initiate("_SecServerBackupKeybagAdd", OS_ACTIVITY_FLAG_DEFAULT, ^{
 600         securityd_send_sync_and_do(kSecXPCOpBackupKeybagAdd, error, ^bool(xpc_object_t message, CFErrorRef *error) {
 601             return SecXPCDictionarySetDataOptional(message, kSecXPCKeyUserPassword, passcode, error);
 602         }, ^bool(xpc_object_t response, CFErrorRef *error) {
 603             result = SecXPCDictionaryCopyDataOptional(response, kSecXPCKeyBackupKeybagIdentifier, identifier, error) &&
 604             SecXPCDictionaryCopyURLOptional(response, kSecXPCKeyBackupKeybagPath, pathinfo, error) &&
 605             SecXPCDictionaryGetBool(response, kSecXPCKeyResult, error);
 606             return result;
 607         });
 608     });
 609     return result;
 610 }
 611
 612 bool SecBackupKeybagDelete(CFDictionaryRef query, CFErrorRef *error) {
 613     __block bool result = false;
 614     os_activity_initiate("_SecBackupKeybagDelete", OS_ACTIVITY_FLAG_DEFAULT, ^{
 615         securityd_send_sync_and_do(kSecXPCOpBackupKeybagDelete, error, ^bool(xpc_object_t message, CFErrorRef *error) {
 616             return SecXPCDictionarySetPList(message, kSecXPCKeyQuery, query, error);
 617         }, ^bool(xpc_object_t response, CFErrorRef *error) {
 618             result = SecXPCDictionaryGetBool(response, kSecXPCKeyResult, error);
 619             return result;
 620         });
 621     });
 622     return result;
 623 }
 624
 625