src/userdb/userwork.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <poll.h>
   4 #include <sys/wait.h>
   5
   6 #include "sd-daemon.h"
   7
   8 #include "env-util.h"
   9 #include "fd-util.h"
  10 #include "group-record.h"
  11 #include "io-util.h"
  12 #include "main-func.h"
  13 #include "process-util.h"
  14 #include "strv.h"
  15 #include "time-util.h"
  16 #include "user-record-nss.h"
  17 #include "user-record.h"
  18 #include "user-util.h"
  19 #include "userdb.h"
  20 #include "varlink.h"
  21
  22 #define ITERATIONS_MAX 64U
  23 #define RUNTIME_MAX_USEC (5 * USEC_PER_MINUTE)
  24 #define PRESSURE_SLEEP_TIME_USEC (50 * USEC_PER_MSEC)
  25 #define CONNECTION_IDLE_USEC (15 * USEC_PER_SEC)
  26 #define LISTEN_IDLE_USEC (90 * USEC_PER_SEC)
  27
  28 typedef struct LookupParameters {
  29         const char *user_name;
  30         const char *group_name;
  31         union {
  32                 uid_t uid;
  33                 gid_t gid;
  34         };
  35         const char *service;
  36 } LookupParameters;
  37
  38 static int add_nss_service(JsonVariant **v) {
  39         _cleanup_(json_variant_unrefp) JsonVariant *status = NULL, *z = NULL;
  40         char buf[SD_ID128_STRING_MAX];
  41         sd_id128_t mid;
  42         int r;
  43
  44         assert(v);
  45
  46         /* Patch in service field if it's missing. The assumption here is that this field is unset only for
  47          * NSS records */
  48
  49         if (json_variant_by_key(*v, "service"))
  50                 return 0;
  51
  52         r = sd_id128_get_machine(&mid);
  53         if (r < 0)
  54                 return r;
  55
  56         status = json_variant_ref(json_variant_by_key(*v, "status"));
  57         z = json_variant_ref(json_variant_by_key(status, sd_id128_to_string(mid, buf)));
  58
  59         if (json_variant_by_key(z, "service"))
  60                 return 0;
  61
  62         r = json_variant_set_field_string(&z, "service", "io.systemd.NameServiceSwitch");
  63         if (r < 0)
  64                 return r;
  65
  66         r = json_variant_set_field(&status, buf, z);
  67         if (r < 0)
  68                 return r;
  69
  70         return json_variant_set_field(v, "status", status);
  71 }
  72
  73 static int build_user_json(Varlink *link, UserRecord *ur, JsonVariant **ret) {
  74         _cleanup_(user_record_unrefp) UserRecord *stripped = NULL;
  75         _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
  76         UserRecordLoadFlags flags;
  77         uid_t peer_uid;
  78         bool trusted;
  79         int r;
  80
  81         assert(ur);
  82         assert(ret);
  83
  84         r = varlink_get_peer_uid(link, &peer_uid);
  85         if (r < 0) {
  86                 log_debug_errno(r, "Unable to query peer UID, ignoring: %m");
  87                 trusted = false;
  88         } else
  89                 trusted = peer_uid == 0 || peer_uid == ur->uid;
  90
  91         flags = USER_RECORD_REQUIRE_REGULAR|USER_RECORD_ALLOW_PER_MACHINE|USER_RECORD_ALLOW_BINDING|USER_RECORD_STRIP_SECRET|USER_RECORD_ALLOW_STATUS|USER_RECORD_ALLOW_SIGNATURE|USER_RECORD_PERMISSIVE;
  92         if (trusted)
  93                 flags |= USER_RECORD_ALLOW_PRIVILEGED;
  94         else
  95                 flags |= USER_RECORD_STRIP_PRIVILEGED;
  96
  97         r = user_record_clone(ur, flags, &stripped);
  98         if (r < 0)
  99                 return r;
 100
 101         stripped->incomplete =
 102                 ur->incomplete ||
 103                 (FLAGS_SET(ur->mask, USER_RECORD_PRIVILEGED) &&
 104                  !FLAGS_SET(stripped->mask, USER_RECORD_PRIVILEGED));
 105
 106         v = json_variant_ref(stripped->json);
 107         r = add_nss_service(&v);
 108         if (r < 0)
 109                 return r;
 110
 111         return json_build(ret, JSON_BUILD_OBJECT(
 112                                           JSON_BUILD_PAIR("record", JSON_BUILD_VARIANT(v)),
 113                                           JSON_BUILD_PAIR("incomplete", JSON_BUILD_BOOLEAN(stripped->incomplete))));
 114 }
 115
 116 static int userdb_flags_from_service(Varlink *link, const char *service, UserDBFlags *ret) {
 117         assert(link);
 118         assert(service);
 119         assert(ret);
 120
 121         if (streq_ptr(service, "io.systemd.NameServiceSwitch"))
 122                 *ret = USERDB_NSS_ONLY|USERDB_AVOID_MULTIPLEXER;
 123         if (streq_ptr(service, "io.systemd.DropIn"))
 124                 *ret = USERDB_DROPIN_ONLY|USERDB_AVOID_MULTIPLEXER;
 125         else if (streq_ptr(service, "io.systemd.Multiplexer"))
 126                 *ret = USERDB_AVOID_MULTIPLEXER;
 127         else
 128                 return varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
 129
 130         return 0;
 131 }
 132
 133 static int vl_method_get_user_record(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
 134
 135         static const JsonDispatch dispatch_table[] = {
 136                 { "uid",      JSON_VARIANT_UNSIGNED, json_dispatch_uid_gid,      offsetof(LookupParameters, uid),       0 },
 137                 { "userName", JSON_VARIANT_STRING,   json_dispatch_const_string, offsetof(LookupParameters, user_name), 0 },
 138                 { "service",  JSON_VARIANT_STRING,   json_dispatch_const_string, offsetof(LookupParameters, service),   0 },
 139                 {}
 140         };
 141
 142         _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
 143         _cleanup_(user_record_unrefp) UserRecord *hr = NULL;
 144         LookupParameters p = {
 145                 .uid = UID_INVALID,
 146         };
 147         UserDBFlags userdb_flags;
 148         int r;
 149
 150         assert(parameters);
 151
 152         r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
 153         if (r < 0)
 154                 return r;
 155
 156         r = userdb_flags_from_service(link, p.service, &userdb_flags);
 157         if (r < 0)
 158                 return r;
 159
 160         if (uid_is_valid(p.uid))
 161                 r = userdb_by_uid(p.uid, userdb_flags, &hr);
 162         else if (p.user_name)
 163                 r = userdb_by_name(p.user_name, userdb_flags, &hr);
 164         else {
 165                 _cleanup_(userdb_iterator_freep) UserDBIterator *iterator = NULL;
 166                 _cleanup_(json_variant_unrefp) JsonVariant *last = NULL;
 167
 168                 r = userdb_all(userdb_flags, &iterator);
 169                 if (r < 0)
 170                         return r;
 171
 172                 for (;;) {
 173                         _cleanup_(user_record_unrefp) UserRecord *z = NULL;
 174
 175                         r = userdb_iterator_get(iterator, &z);
 176                         if (r == -ESRCH)
 177                                 break;
 178                         if (r < 0)
 179                                 return r;
 180
 181                         if (last) {
 182                                 r = varlink_notify(link, last);
 183                                 if (r < 0)
 184                                         return r;
 185
 186                                 last = json_variant_unref(last);
 187                         }
 188
 189                         r = build_user_json(link, z, &last);
 190                         if (r < 0)
 191                                 return r;
 192                 }
 193
 194                 if (!last)
 195                         return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
 196
 197                 return varlink_reply(link, last);
 198         }
 199         if (r == -ESRCH)
 200                 return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
 201         if (r < 0) {
 202                 log_debug_errno(r, "User lookup failed abnormally: %m");
 203                 return varlink_error(link, "io.systemd.UserDatabase.ServiceNotAvailable", NULL);
 204         }
 205
 206         if ((uid_is_valid(p.uid) && hr->uid != p.uid) ||
 207             (p.user_name && !streq(hr->user_name, p.user_name)))
 208                 return varlink_error(link, "io.systemd.UserDatabase.ConflictingRecordFound", NULL);
 209
 210         r = build_user_json(link, hr, &v);
 211         if (r < 0)
 212                 return r;
 213
 214         return varlink_reply(link, v);
 215 }
 216
 217 static int build_group_json(Varlink *link, GroupRecord *gr, JsonVariant **ret) {
 218         _cleanup_(group_record_unrefp) GroupRecord *stripped = NULL;
 219         _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
 220         UserRecordLoadFlags flags;
 221         uid_t peer_uid;
 222         bool trusted;
 223         int r;
 224
 225         assert(gr);
 226         assert(ret);
 227
 228         r = varlink_get_peer_uid(link, &peer_uid);
 229         if (r < 0) {
 230                 log_debug_errno(r, "Unable to query peer UID, ignoring: %m");
 231                 trusted = false;
 232         } else
 233                 trusted = peer_uid == 0;
 234
 235         flags = USER_RECORD_REQUIRE_REGULAR|USER_RECORD_ALLOW_PER_MACHINE|USER_RECORD_ALLOW_BINDING|USER_RECORD_STRIP_SECRET|USER_RECORD_ALLOW_STATUS|USER_RECORD_ALLOW_SIGNATURE|USER_RECORD_PERMISSIVE;
 236         if (trusted)
 237                 flags |= USER_RECORD_ALLOW_PRIVILEGED;
 238         else
 239                 flags |= USER_RECORD_STRIP_PRIVILEGED;
 240
 241         r = group_record_clone(gr, flags, &stripped);
 242         if (r < 0)
 243                 return r;
 244
 245         stripped->incomplete =
 246                 gr->incomplete ||
 247                 (FLAGS_SET(gr->mask, USER_RECORD_PRIVILEGED) &&
 248                  !FLAGS_SET(stripped->mask, USER_RECORD_PRIVILEGED));
 249
 250         v = json_variant_ref(gr->json);
 251         r = add_nss_service(&v);
 252         if (r < 0)
 253                 return r;
 254
 255         return json_build(ret, JSON_BUILD_OBJECT(
 256                                           JSON_BUILD_PAIR("record", JSON_BUILD_VARIANT(v)),
 257                                           JSON_BUILD_PAIR("incomplete", JSON_BUILD_BOOLEAN(stripped->incomplete))));
 258 }
 259
 260 static int vl_method_get_group_record(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
 261
 262         static const JsonDispatch dispatch_table[] = {
 263                 { "gid",       JSON_VARIANT_UNSIGNED, json_dispatch_uid_gid,      offsetof(LookupParameters, gid),        0 },
 264                 { "groupName", JSON_VARIANT_STRING,   json_dispatch_const_string, offsetof(LookupParameters, group_name), 0 },
 265                 { "service",   JSON_VARIANT_STRING,   json_dispatch_const_string, offsetof(LookupParameters, service),    0 },
 266                 {}
 267         };
 268
 269         _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
 270         _cleanup_(group_record_unrefp) GroupRecord *g = NULL;
 271         LookupParameters p = {
 272                 .gid = GID_INVALID,
 273         };
 274         UserDBFlags userdb_flags;
 275         int r;
 276
 277         assert(parameters);
 278
 279         r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
 280         if (r < 0)
 281                 return r;
 282
 283         r = userdb_flags_from_service(link, p.service, &userdb_flags);
 284         if (r < 0)
 285                 return r;
 286
 287         if (gid_is_valid(p.gid))
 288                 r = groupdb_by_gid(p.gid, userdb_flags, &g);
 289         else if (p.group_name)
 290                 r = groupdb_by_name(p.group_name, userdb_flags, &g);
 291         else {
 292                 _cleanup_(userdb_iterator_freep) UserDBIterator *iterator = NULL;
 293                 _cleanup_(json_variant_unrefp) JsonVariant *last = NULL;
 294
 295                 r = groupdb_all(userdb_flags, &iterator);
 296                 if (r < 0)
 297                         return r;
 298
 299                 for (;;) {
 300                         _cleanup_(group_record_unrefp) GroupRecord *z = NULL;
 301
 302                         r = groupdb_iterator_get(iterator, &z);
 303                         if (r == -ESRCH)
 304                                 break;
 305                         if (r < 0)
 306                                 return r;
 307
 308                         if (last) {
 309                                 r = varlink_notify(link, last);
 310                                 if (r < 0)
 311                                         return r;
 312
 313                                 last = json_variant_unref(last);
 314                         }
 315
 316                         r = build_group_json(link, z, &last);
 317                         if (r < 0)
 318                                 return r;
 319                 }
 320
 321                 if (!last)
 322                         return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
 323
 324                 return varlink_reply(link, last);
 325         }
 326         if (r == -ESRCH)
 327                 return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
 328         if (r < 0) {
 329                 log_debug_errno(r, "Group lookup failed abnormally: %m");
 330                 return varlink_error(link, "io.systemd.UserDatabase.ServiceNotAvailable", NULL);
 331         }
 332
 333         if ((uid_is_valid(p.gid) && g->gid != p.gid) ||
 334             (p.group_name && !streq(g->group_name, p.group_name)))
 335                 return varlink_error(link, "io.systemd.UserDatabase.ConflictingRecordFound", NULL);
 336
 337         r = build_group_json(link, g, &v);
 338         if (r < 0)
 339                 return r;
 340
 341         return varlink_reply(link, v);
 342 }
 343
 344 static int vl_method_get_memberships(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
 345         static const JsonDispatch dispatch_table[] = {
 346                 { "userName",  JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, user_name), 0 },
 347                 { "groupName", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, group_name), 0 },
 348                 { "service",   JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, service),   0 },
 349                 {}
 350         };
 351
 352         _cleanup_free_ char *last_user_name = NULL, *last_group_name = NULL;
 353         _cleanup_(userdb_iterator_freep) UserDBIterator *iterator = NULL;
 354         LookupParameters p = {};
 355         UserDBFlags userdb_flags;
 356         int r;
 357
 358         assert(parameters);
 359
 360         r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
 361         if (r < 0)
 362                 return r;
 363
 364         r = userdb_flags_from_service(link, p.service, &userdb_flags);
 365         if (r < 0)
 366                 return r;
 367
 368         if (p.group_name)
 369                 r = membershipdb_by_group(p.group_name, userdb_flags, &iterator);
 370         else if (p.user_name)
 371                 r = membershipdb_by_user(p.user_name, userdb_flags, &iterator);
 372         else
 373                 r = membershipdb_all(userdb_flags, &iterator);
 374         if (r < 0)
 375                 return r;
 376
 377         for (;;) {
 378                 _cleanup_free_ char *user_name = NULL, *group_name = NULL;
 379
 380                 r = membershipdb_iterator_get(iterator, &user_name, &group_name);
 381                 if (r == -ESRCH)
 382                         break;
 383                 if (r < 0)
 384                         return r;
 385
 386                 /* If both group + user are specified do a-posteriori filtering */
 387                 if (p.group_name && p.user_name && !streq(group_name, p.group_name))
 388                         continue;
 389
 390                 if (last_user_name) {
 391                         assert(last_group_name);
 392
 393                         r = varlink_notifyb(link, JSON_BUILD_OBJECT(
 394                                                             JSON_BUILD_PAIR("userName", JSON_BUILD_STRING(last_user_name)),
 395                                                             JSON_BUILD_PAIR("groupName", JSON_BUILD_STRING(last_group_name))));
 396                         if (r < 0)
 397                                 return r;
 398                 }
 399
 400                 free_and_replace(last_user_name, user_name);
 401                 free_and_replace(last_group_name, group_name);
 402         }
 403
 404         if (!last_user_name) {
 405                 assert(!last_group_name);
 406                 return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
 407         }
 408
 409         assert(last_group_name);
 410
 411         return varlink_replyb(link, JSON_BUILD_OBJECT(
 412                                               JSON_BUILD_PAIR("userName", JSON_BUILD_STRING(last_user_name)),
 413                                               JSON_BUILD_PAIR("groupName", JSON_BUILD_STRING(last_group_name))));
 414 }
 415
 416 static int process_connection(VarlinkServer *server, int fd) {
 417         _cleanup_(varlink_close_unrefp) Varlink *vl = NULL;
 418         int r;
 419
 420         r = varlink_server_add_connection(server, fd, &vl);
 421         if (r < 0) {
 422                 fd = safe_close(fd);
 423                 return log_error_errno(r, "Failed to add connection: %m");
 424         }
 425
 426         vl = varlink_ref(vl);
 427
 428         for (;;) {
 429                 r = varlink_process(vl);
 430                 if (r == -ENOTCONN) {
 431                         log_debug("Connection terminated.");
 432                         break;
 433                 }
 434                 if (r < 0)
 435                         return log_error_errno(r, "Failed to process connection: %m");
 436                 if (r > 0)
 437                         continue;
 438
 439                 r = varlink_wait(vl, CONNECTION_IDLE_USEC);
 440                 if (r < 0)
 441                         return log_error_errno(r, "Failed to wait for connection events: %m");
 442                 if (r == 0)
 443                         break;
 444         }
 445
 446         return 0;
 447 }
 448
 449 static int run(int argc, char *argv[]) {
 450         usec_t start_time, listen_idle_usec, last_busy_usec = USEC_INFINITY;
 451         _cleanup_(varlink_server_unrefp) VarlinkServer *server = NULL;
 452         unsigned n_iterations = 0;
 453         int m, listen_fd, r;
 454
 455         log_setup();
 456
 457         m = sd_listen_fds(false);
 458         if (m < 0)
 459                 return log_error_errno(m, "Failed to determine number of listening fds: %m");
 460         if (m == 0)
 461                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "No socket to listen on received.");
 462         if (m > 1)
 463                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Worker can only listen on a single socket at a time.");
 464
 465         listen_fd = SD_LISTEN_FDS_START;
 466
 467         r = fd_nonblock(listen_fd, false);
 468         if (r < 0)
 469                 return log_error_errno(r, "Failed to turn off non-blocking mode for listening socket: %m");
 470
 471         r = varlink_server_new(&server, 0);
 472         if (r < 0)
 473                 return log_error_errno(r, "Failed to allocate server: %m");
 474
 475         r = varlink_server_bind_method_many(
 476                         server,
 477                         "io.systemd.UserDatabase.GetUserRecord",  vl_method_get_user_record,
 478                         "io.systemd.UserDatabase.GetGroupRecord", vl_method_get_group_record,
 479                         "io.systemd.UserDatabase.GetMemberships", vl_method_get_memberships);
 480         if (r < 0)
 481                 return log_error_errno(r, "Failed to bind methods: %m");
 482
 483         r = getenv_bool("USERDB_FIXED_WORKER");
 484         if (r < 0)
 485                 return log_error_errno(r, "Failed to parse USERDB_FIXED_WORKER: %m");
 486         listen_idle_usec = r ? USEC_INFINITY : LISTEN_IDLE_USEC;
 487
 488         r = userdb_block_nss_systemd(true);
 489         if (r < 0)
 490                 return log_error_errno(r, "Failed to disable userdb NSS compatibility: %m");
 491
 492         start_time = now(CLOCK_MONOTONIC);
 493
 494         for (;;) {
 495                 _cleanup_close_ int fd = -1;
 496                 usec_t n;
 497
 498                 /* Exit the worker in regular intervals, to flush out all memory use */
 499                 if (n_iterations++ > ITERATIONS_MAX) {
 500                         log_debug("Exiting worker, processed %u iterations, that's enough.", n_iterations);
 501                         break;
 502                 }
 503
 504                 n = now(CLOCK_MONOTONIC);
 505                 if (n >= usec_add(start_time, RUNTIME_MAX_USEC)) {
 506                         char buf[FORMAT_TIMESPAN_MAX];
 507                         log_debug("Exiting worker, ran for %s, that's enough.",
 508                                   format_timespan(buf, sizeof(buf), usec_sub_unsigned(n, start_time), 0));
 509                         break;
 510                 }
 511
 512                 if (last_busy_usec == USEC_INFINITY)
 513                         last_busy_usec = n;
 514                 else if (listen_idle_usec != USEC_INFINITY && n >= usec_add(last_busy_usec, listen_idle_usec)) {
 515                         char buf[FORMAT_TIMESPAN_MAX];
 516                         log_debug("Exiting worker, been idle for %s.",
 517                                   format_timespan(buf, sizeof(buf), usec_sub_unsigned(n, last_busy_usec), 0));
 518                         break;
 519                 }
 520
 521                 (void) rename_process("systemd-userwork: waiting...");
 522
 523                 fd = accept4(listen_fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
 524                 if (fd < 0)
 525                         fd = -errno;
 526
 527                 (void) rename_process("systemd-userwork: processing...");
 528
 529                 if (fd == -EAGAIN)
 530                         continue; /* The listening socket has SO_RECVTIMEO set, hence a timeout is expected
 531                                    * after a while, let's check if it's time to exit though. */
 532                 if (fd == -EINTR)
 533                         continue; /* Might be that somebody attached via strace, let's just continue in that
 534                                    * case */
 535                 if (fd < 0)
 536                         return log_error_errno(fd, "Failed to accept() from listening socket: %m");
 537
 538                 if (now(CLOCK_MONOTONIC) <= usec_add(n, PRESSURE_SLEEP_TIME_USEC)) {
 539                         /* We only slept a very short time? If so, let's see if there are more sockets
 540                          * pending, and if so, let's ask our parent for more workers */
 541
 542                         r = fd_wait_for_event(listen_fd, POLLIN, 0);
 543                         if (r < 0)
 544                                 return log_error_errno(r, "Failed to test for POLLIN on listening socket: %m");
 545
 546                         if (FLAGS_SET(r, POLLIN)) {
 547                                 pid_t parent;
 548
 549                                 parent = getppid();
 550                                 if (parent <= 1)
 551                                         return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Parent already died?");
 552
 553                                 if (kill(parent, SIGUSR2) < 0)
 554                                         return log_error_errno(errno, "Failed to kill our own parent.");
 555                         }
 556                 }
 557
 558                 (void) process_connection(server, TAKE_FD(fd));
 559                 last_busy_usec = USEC_INFINITY;
 560         }
 561
 562         return 0;
 563 }
 564
 565 DEFINE_MAIN_FUNCTION(run);