libsecurity_keychain/xpc/main.c

   1 /*
   2  * Copyright (c) 2011 Apple Computer, 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 #include <xpc/private.h>
  25 #include <syslog.h>
  26 #include <sys/param.h>
  27 #include <sandbox.h>
  28 #include <dlfcn.h>
  29 #include <sysexits.h>
  30 #include <Security/Security.h>
  31 #include <stdlib.h>
  32 #include <libgen.h>
  33 #include <string.h>
  34 #include <CommonCrypto/CommonDigest.h>
  35 #include <CoreFoundation/CoreFoundation.h>
  36 #include <sys/types.h>
  37 #include <pwd.h>
  38
  39 struct connection_info {
  40     xpc_connection_t peer;
  41     int processed;
  42     int done;
  43 };
  44
  45 typedef typeof(SecKeychainCopyDomainSearchList) SecKeychainCopyDomainSearchListType;
  46 SecKeychainCopyDomainSearchListType *SecKeychainCopyDomainSearchListFunctionPointer = NULL;
  47 typedef typeof(SecKeychainGetPath) SecKeychainGetPathType;
  48 SecKeychainGetPathType *SecKeychainGetPathFunctionPointer = NULL;
  49
  50 // prior to 8723022 we have to do our own idle timeout work
  51 #ifndef XPC_HANDLES_IDLE_TIMEOUT
  52 int current_connections = 0;
  53 // Number of seconds to sit with no clients
  54 #define IDLE_WAIT_TIME 30
  55 #endif
  56
  57 xpc_object_t keychain_prefs_path = NULL;
  58 xpc_object_t home = NULL;
  59
  60 extern xpc_object_t
  61 xpc_create_reply_with_format(xpc_object_t original, const char * format, ...);
  62
  63 xpc_object_t create_keychain_search_list_for(xpc_connection_t peer, SecPreferencesDomain domain)
  64 {
  65     CFArrayRef keychains = NULL;
  66     pid_t peer_pid = xpc_connection_get_pid(peer);
  67     OSStatus status = SecKeychainCopyDomainSearchListFunctionPointer(domain, &keychains);
  68     if (noErr != status) {
  69         syslog(LOG_ERR, "Unable to get keychain search list (domain=%d) on behalf of %d, status=0x%lx", domain, peer_pid, status);
  70         return NULL;
  71     }
  72
  73     xpc_object_t paths = xpc_array_create(NULL, 0);
  74         CFIndex n_keychains = CFArrayGetCount(keychains);
  75         CFIndex i;
  76         for(i = 0; i < n_keychains; i++) {
  77                 char path[MAXPATHLEN];
  78
  79         SecKeychainRef keychain = (SecKeychainRef)CFArrayGetValueAtIndex(keychains, i);
  80         UInt32 length = MAXPATHLEN;
  81         OSStatus status = SecKeychainGetPathFunctionPointer(keychain, &length, path);
  82         if (noErr != status) {
  83             syslog(LOG_ERR, "Unable to get path for keychain#%ld of %ld on behalf of %d, status=0x%lx", i, n_keychains, peer_pid, status);
  84             continue;
  85         }
  86         xpc_object_t path_as_xpc_string = xpc_string_create(path);
  87                 xpc_array_append_value(paths, path_as_xpc_string);
  88         xpc_release(path_as_xpc_string);
  89         }
  90     CFRelease(keychains);
  91     return paths;
  92 }
  93
  94 bool keychain_domain_needs_writes(const char *domain_name)
  95 {
  96         return (0 == strcmp("kSecPreferencesDomainUser", domain_name) || 0 == strcmp("kSecPreferencesDomainDynamic", domain_name));
  97 }
  98
  99 void _set_keychain_search_lists_for_domain(xpc_connection_t peer, xpc_object_t all_domains, char *domain_name, SecPreferencesDomain domain_enum)
 100 {
 101     xpc_object_t keychains_for_domain = create_keychain_search_list_for(peer, domain_enum);
 102     if (keychains_for_domain) {
 103         xpc_dictionary_set_value(all_domains, domain_name, keychains_for_domain);
 104         xpc_release(keychains_for_domain);
 105     } else {
 106         syslog(LOG_ERR, "Can't discover keychain paths for domain %s on behalf of %d", domain_name, xpc_connection_get_pid(peer));
 107     }
 108 }
 109
 110 #define SET_KEYCHAIN_SEARCH_LISTS_FOR_DOMAIN(peer, all_domains, domain) _set_keychain_search_lists_for_domain(peer, all_domains, #domain, domain);
 111
 112 xpc_object_t create_keychain_search_lists(xpc_connection_t peer)
 113 {
 114         xpc_object_t all_domains = xpc_dictionary_create(NULL, NULL, 0);
 115
 116     SET_KEYCHAIN_SEARCH_LISTS_FOR_DOMAIN(peer, all_domains, kSecPreferencesDomainUser);
 117     SET_KEYCHAIN_SEARCH_LISTS_FOR_DOMAIN(peer, all_domains, kSecPreferencesDomainSystem);
 118     SET_KEYCHAIN_SEARCH_LISTS_FOR_DOMAIN(peer, all_domains, kSecPreferencesDomainCommon);
 119     SET_KEYCHAIN_SEARCH_LISTS_FOR_DOMAIN(peer, all_domains, kSecPreferencesDomainDynamic);
 120
 121     return all_domains;
 122 }
 123
 124
 125 xpc_object_t create_keychain_and_lock_paths(xpc_connection_t peer, xpc_object_t keychain_path_dict)
 126 {
 127         pid_t peer_pid = xpc_connection_get_pid(peer);
 128         char *assembly_queue_label = NULL;
 129     asprintf(&assembly_queue_label, "assembly-for-%d", peer_pid);
 130     if (!assembly_queue_label) {
 131         syslog(LOG_ERR, "Unable to create assembly queue label for %d", peer_pid);
 132         return NULL;
 133     }
 134     dispatch_queue_t assembly_queue = dispatch_queue_create(assembly_queue_label, 0);
 135     free(assembly_queue_label);
 136     if (!assembly_queue) {
 137         syslog(LOG_ERR, "Unable to create assembly queue for %d", peer_pid);
 138         return NULL;
 139     }
 140         xpc_object_t return_paths_dict = xpc_dictionary_create(NULL, NULL, 0);
 141
 142         xpc_dictionary_apply(keychain_path_dict, ^(const char *keychain_domain, xpc_object_t keychain_path_array) {
 143                 xpc_object_t return_paths_array = xpc_array_create(NULL, 0);
 144                 dispatch_apply(xpc_array_get_count(keychain_path_array), dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(size_t i) {
 145                         xpc_object_t path_as_xpc_string = xpc_array_get_value(keychain_path_array, i);
 146                         dispatch_sync(assembly_queue, ^{
 147                                 xpc_array_append_value(return_paths_array, path_as_xpc_string);
 148                         });
 149
 150                         if (!keychain_domain_needs_writes(keychain_domain)) {
 151                                 // lock files are only to prevent write-write errors, readers don't hold locks, so they don't need the lock files
 152                                 return;
 153                         }
 154
 155             // figure out the base and dir
 156             const char* path = xpc_array_get_string(keychain_path_array, i);
 157             char* dir;
 158             char* base;
 159
 160             char buffer[PATH_MAX];
 161             strcpy(buffer, path);
 162
 163             if (path != NULL) {
 164                 int i = strlen(buffer) - 1;
 165                 while (i >= 0 && buffer[i] != '/') {
 166                     i -= 1;
 167                 }
 168
 169                 if (i >= 0) {
 170                     // NULL terminate the dir
 171                     buffer[i] = 0;
 172                     dir = buffer;
 173                     base = buffer + i + 1;
 174                 } else {
 175                     dir = NULL;
 176                     base = buffer;
 177                 }
 178             }
 179
 180             if (!(path && dir && base)) {
 181                 syslog(LOG_ERR, "Can't get dir or base (likely out of memory) for %s", xpc_array_get_string(keychain_path_array, i));
 182                 return;
 183             }
 184
 185                         // "network style" lock files
 186                         path_as_xpc_string = xpc_string_create_with_format("%s/lck~%s", dir, base);
 187                         dispatch_sync(assembly_queue, ^{
 188                                 xpc_array_append_value(return_paths_array, path_as_xpc_string);
 189                         });
 190                         xpc_release(path_as_xpc_string);
 191
 192             CC_SHA1_CTX sha1Context;
 193             CC_SHA1_Init(&sha1Context);
 194             CC_SHA1_Update(&sha1Context, base, strlen(base));
 195
 196             unsigned char sha1_result_bytes[CC_SHA1_DIGEST_LENGTH];
 197
 198             CC_SHA1_Final(sha1_result_bytes, &sha1Context);
 199
 200                         path_as_xpc_string = xpc_string_create_with_format("%s/.fl%02X%02X%02X%02X", dir, sha1_result_bytes[0], sha1_result_bytes[1], sha1_result_bytes[2], sha1_result_bytes[3]);
 201                         dispatch_sync(assembly_queue, ^{
 202                                 xpc_array_append_value(return_paths_array, path_as_xpc_string);
 203                         });
 204                 });
 205                 xpc_dictionary_set_value(return_paths_dict, keychain_domain, return_paths_array);
 206                 xpc_release(return_paths_array);
 207                 return (bool)true;
 208         });
 209
 210         dispatch_release(assembly_queue);
 211         return return_paths_dict;
 212 }
 213
 214 xpc_object_t create_one_sandbox_extension(xpc_object_t path, uint64_t extension_flags)
 215 {
 216         char *sandbox_extension = NULL;
 217         int status = sandbox_issue_fs_extension(xpc_string_get_string_ptr(path), extension_flags, &sandbox_extension);
 218         if (0 == status && sandbox_extension) {
 219                 xpc_object_t sandbox_extension_as_xpc_string = xpc_string_create(sandbox_extension);
 220         free(sandbox_extension);
 221         return sandbox_extension_as_xpc_string;
 222         } else {
 223                 syslog(LOG_ERR, "Can't get sandbox fs extension for %s, status=%d errno=%m ext=%s", xpc_string_get_string_ptr(path), status, sandbox_extension);
 224         }
 225         return NULL;
 226 }
 227
 228 xpc_object_t create_all_sandbox_extensions(xpc_object_t path_dict)
 229 {
 230     xpc_object_t extensions = xpc_array_create(NULL, 0);
 231
 232         xpc_object_t sandbox_extension = create_one_sandbox_extension(keychain_prefs_path, FS_EXT_FOR_PATH|FS_EXT_READ);
 233         if (sandbox_extension) {
 234                 xpc_array_append_value(extensions, sandbox_extension);
 235                 xpc_release(sandbox_extension);
 236         }
 237
 238         xpc_dictionary_apply(path_dict, ^(const char *keychain_domain, xpc_object_t path_array) {
 239                 uint64_t extension_flags = FS_EXT_FOR_PATH|FS_EXT_READ;
 240                 if (keychain_domain_needs_writes(keychain_domain)) {
 241                         extension_flags = FS_EXT_FOR_PATH|FS_EXT_READ|FS_EXT_WRITE;
 242                 }
 243                 xpc_array_apply(path_array, ^(size_t index, xpc_object_t path) {
 244                         xpc_object_t sandbox_extension = create_one_sandbox_extension(path, extension_flags);
 245                         if (sandbox_extension) {
 246                                 xpc_array_append_value(extensions, sandbox_extension);
 247                                 xpc_release(sandbox_extension);
 248                         }
 249                         return (bool)true;
 250                 });
 251                 return (bool)true;
 252         });
 253
 254     return extensions;
 255 }
 256
 257 void handle_request_event(struct connection_info *info, xpc_object_t event)
 258 {
 259     xpc_connection_t peer = xpc_dictionary_get_connection(event);
 260     xpc_type_t xtype = xpc_get_type(event);
 261     if (info->done) {
 262         syslog(LOG_ERR, "event %p while done", event);
 263         return;
 264     }
 265         if (xtype == XPC_TYPE_ERROR) {
 266                 if (event == XPC_ERROR_TERMINATION_IMMINENT) {
 267                         // launchd would like us to die, but we have open transactions.   When we finish with them xpc_service_main
 268                         // will exit for us, so there is nothing for us to do here.
 269                         return;
 270                 }
 271
 272         if (!info->done) {
 273             info->done = true;
 274             xpc_release(info->peer);
 275 #ifndef XPC_HANDLES_IDLE_TIMEOUT
 276             if (0 == __sync_add_and_fetch(&current_connections, -1)) {
 277                 dispatch_after(dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC * IDLE_WAIT_TIME), dispatch_get_main_queue(), ^(void) {
 278                     if (0 == current_connections) {
 279                         exit(0);
 280                     }
 281                 });
 282             }
 283 #endif
 284         }
 285         if (peer == NULL && XPC_ERROR_CONNECTION_INVALID == event && 0 != info->processed) {
 286             // this is a normal shutdown on a connection that has processed at least
 287             // one request.   Nothing intresting to log.
 288             return;
 289         }
 290                 syslog(LOG_ERR, "listener event error (connection %p): %s", peer, xpc_dictionary_get_string(event, XPC_ERROR_KEY_DESCRIPTION));
 291         } else if (xtype == XPC_TYPE_DICTIONARY) {
 292         const char *operation = xpc_dictionary_get_string(event, "op");
 293         if (operation && !strcmp(operation, "GrantKeychainPaths")) {
 294             xpc_object_t keychain_paths = create_keychain_search_lists(peer);
 295                         xpc_object_t all_paths = create_keychain_and_lock_paths(peer, keychain_paths);
 296             xpc_object_t sandbox_extensions = NULL;
 297             if (all_paths) {
 298                 sandbox_extensions = create_all_sandbox_extensions(all_paths);
 299             }
 300
 301             xpc_object_t reply = xpc_create_reply_with_format(event, "{keychain-paths: %value, all-paths: %value, extensions: %value, keychain-home: %value}",
 302                                                                                                                           keychain_paths, all_paths, sandbox_extensions, home);
 303             xpc_connection_send_message(peer, reply);
 304             xpc_release(reply);
 305             if (keychain_paths) {
 306                 xpc_release(keychain_paths);
 307             }
 308             if (all_paths) {
 309                 xpc_release(all_paths);
 310             }
 311             if (sandbox_extensions) {
 312                 xpc_release(sandbox_extensions);
 313             }
 314             if (INT32_MAX != info->processed) {
 315                 info->processed++;
 316             }
 317         } else {
 318             syslog(LOG_ERR, "Unknown op=%s request from pid %d", operation, xpc_connection_get_pid(peer));
 319         }
 320     } else {
 321                 syslog(LOG_ERR, "Unhandled request event=%p type=%p", event, xtype);
 322     }
 323 }
 324
 325 void finalize_connection(void *not_used)
 326 {
 327 #ifdef XPC_HANDLES_IDLE_TIMEOUT
 328         xpc_transaction_end();
 329 #endif
 330 }
 331
 332 void handle_connection_event(const xpc_connection_t peer)
 333 {
 334 #ifndef XPC_HANDLES_IDLE_TIMEOUT
 335     __sync_add_and_fetch(&current_connections, 1);
 336 #endif
 337     __block struct connection_info info;
 338     info.peer = peer;
 339     info.processed = 0;
 340     info.done = false;
 341
 342     xpc_connection_set_event_handler(peer, ^(xpc_object_t event) {
 343         handle_request_event(&info, event);
 344     });
 345
 346     //  unlike dispatch objects xpc objects don't need a context set in order to run a finalizer.   (we use our finalizer to
 347     // end the transaction we are about to begin...this keeps xpc from idle exiting us while we have a live connection)
 348     xpc_connection_set_finalizer_f(peer, finalize_connection);
 349 #ifdef XPC_HANDLES_IDLE_TIMEOUT
 350     xpc_transaction_begin();
 351 #endif
 352
 353     // enable the peer connection to receive messages
 354     xpc_connection_resume(peer);
 355     xpc_retain(peer);
 356 }
 357
 358
 359 static const char* g_path_to_plist = "/Library/Preferences/com.apple.security.plist";
 360
 361
 362
 363 int main(int argc, const char *argv[])
 364 {
 365     char *wait4debugger = getenv("WAIT4DEBUGGER");
 366     if (wait4debugger && !strcasecmp("YES", wait4debugger)) {
 367         syslog(LOG_ERR, "Waiting for debugger");
 368         kill(getpid(), SIGSTOP);
 369     }
 370
 371     // get the home directory
 372     const char* home_dir = getenv("HOME");
 373
 374     if (home_dir == NULL || strlen(home_dir) == 0) {
 375         struct passwd* pwd = getpwuid(getuid());
 376         home_dir = pwd->pw_dir; // look it up in directory services, sort of...
 377     }
 378
 379     int home_dir_length = strlen(home_dir);
 380     int path_to_plist_length = strlen(g_path_to_plist);
 381
 382     int total_length = home_dir_length + path_to_plist_length + 1; // compensate for terminating zero
 383     if (total_length > PATH_MAX) {
 384         // someone is spoofing us, just exit
 385         return -1;
 386     }
 387
 388     // make storage for the real path
 389     char buffer[total_length];
 390     strlcpy(buffer, home_dir, total_length);
 391     strlcat(buffer, g_path_to_plist, total_length);
 392     keychain_prefs_path = xpc_string_create(buffer);
 393     home = xpc_string_create(home_dir);
 394
 395     void *security_framework = dlopen("/System/Library/Frameworks/Security.framework/Security", RTLD_LAZY);
 396     if (security_framework) {
 397         SecKeychainCopyDomainSearchListFunctionPointer = dlsym(security_framework, "SecKeychainCopyDomainSearchList");
 398         if (!SecKeychainCopyDomainSearchListFunctionPointer) {
 399             syslog(LOG_ERR, "Can't lookup SecKeychainCopyDomainSearchList in %p: %s", security_framework, dlerror());
 400             return EX_OSERR;
 401         }
 402         SecKeychainGetPathFunctionPointer = dlsym(security_framework, "SecKeychainGetPath");
 403         if (!SecKeychainGetPathFunctionPointer) {
 404             syslog(LOG_ERR, "Can't lookup SecKeychainGetPath in %p: %s", security_framework, dlerror());
 405             return EX_OSERR;
 406         }
 407     }
 408
 409     xpc_main(handle_connection_event);
 410
 411     return EX_OSERR;
 412 }