automount.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <limits.h>
  24 #include <sys/mount.h>
  25 #include <unistd.h>
  26 #include <fcntl.h>
  27 #include <sys/epoll.h>
  28 #include <sys/stat.h>
  29 #include <linux/auto_fs4.h>
  30 #include <linux/auto_dev-ioctl.h>
  31
  32 #include "unit.h"
  33 #include "automount.h"
  34 #include "load-fragment.h"
  35 #include "load-dropin.h"
  36 #include "unit-name.h"
  37 #include "dbus-automount.h"
  38
  39 static const UnitActiveState state_translation_table[_AUTOMOUNT_STATE_MAX] = {
  40         [AUTOMOUNT_DEAD] = UNIT_INACTIVE,
  41         [AUTOMOUNT_WAITING] = UNIT_ACTIVE,
  42         [AUTOMOUNT_RUNNING] = UNIT_ACTIVE,
  43         [AUTOMOUNT_MAINTAINANCE] = UNIT_INACTIVE,
  44 };
  45
  46 static const char* const state_string_table[_AUTOMOUNT_STATE_MAX] = {
  47         [AUTOMOUNT_DEAD] = "dead",
  48         [AUTOMOUNT_WAITING] = "waiting",
  49         [AUTOMOUNT_RUNNING] = "running",
  50         [AUTOMOUNT_MAINTAINANCE] = "maintainance"
  51 };
  52
  53 static char *automount_name_from_where(const char *where) {
  54         assert(where);
  55
  56         if (streq(where, "/"))
  57                 return strdup("-.automount");
  58
  59         return unit_name_build_escape(where+1, NULL, ".automount");
  60 }
  61
  62 static void automount_init(Unit *u) {
  63         Automount *a = AUTOMOUNT(u);
  64
  65         assert(u);
  66         assert(u->meta.load_state == UNIT_STUB);
  67
  68         a->pipe_watch.fd = a->pipe_fd = -1;
  69 }
  70
  71 static void repeat_unmout(const char *path) {
  72         assert(path);
  73
  74         for (;;) {
  75
  76                 if (umount2(path, MNT_DETACH) >= 0)
  77                         continue;
  78
  79                 if (errno != EINVAL)
  80                         log_error("Failed to unmount: %m");
  81
  82                 break;
  83         }
  84 }
  85
  86 static void unmount_autofs(Automount *a) {
  87         assert(a);
  88
  89         if (a->pipe_fd < 0)
  90                 return;
  91
  92         automount_send_ready(a, -EHOSTDOWN);
  93
  94         unit_unwatch_fd(UNIT(a), &a->pipe_watch);
  95         close_nointr_nofail(a->pipe_fd);
  96         a->pipe_fd = -1;
  97
  98         repeat_unmout(a->where);
  99 }
 100
 101 static void automount_done(Unit *u) {
 102         Automount *a = AUTOMOUNT(u);
 103
 104         assert(a);
 105
 106         unmount_autofs(a);
 107         a->mount = NULL;
 108
 109         if (a->tokens) {
 110                 set_free(a->tokens);
 111                 a->tokens = NULL;
 112         }
 113 }
 114
 115 static int automount_verify(Automount *a) {
 116         bool b;
 117         char *e;
 118         assert(a);
 119
 120         if (UNIT(a)->meta.load_state != UNIT_LOADED)
 121                 return 0;
 122
 123         if (!a->where) {
 124                 log_error("%s lacks Where setting. Refusing.", UNIT(a)->meta.id);
 125                 return -EINVAL;
 126         }
 127
 128         path_kill_slashes(a->where);
 129
 130         if (!(e = automount_name_from_where(a->where)))
 131                 return -ENOMEM;
 132
 133         b = unit_has_name(UNIT(a), e);
 134         free(e);
 135
 136         if (!b) {
 137                 log_error("%s's Where setting doesn't match unit name. Refusing.", UNIT(a)->meta.id);
 138                 return -EINVAL;
 139         }
 140
 141         return 0;
 142 }
 143
 144 static int automount_load(Unit *u) {
 145         int r;
 146         Automount *a = AUTOMOUNT(u);
 147
 148         assert(u);
 149         assert(u->meta.load_state == UNIT_STUB);
 150
 151         /* Load a .automount file */
 152         if ((r = unit_load_fragment_and_dropin_optional(u)) < 0)
 153                 return r;
 154
 155         if (u->meta.load_state == UNIT_LOADED) {
 156
 157                 if ((r = unit_load_related_unit(u, ".mount", (Unit**) &a->mount)) < 0)
 158                         return r;
 159
 160                 if ((r = unit_add_dependency(u, UNIT_BEFORE, UNIT(a->mount))) < 0)
 161                         return r;
 162         }
 163
 164         return automount_verify(a);
 165 }
 166
 167 static void automount_set_state(Automount *a, AutomountState state) {
 168         AutomountState old_state;
 169         assert(a);
 170
 171         old_state = a->state;
 172         a->state = state;
 173
 174         if (state != AUTOMOUNT_WAITING &&
 175             state != AUTOMOUNT_RUNNING)
 176                 unmount_autofs(a);
 177
 178         if (state != old_state)
 179                 log_debug("%s changed %s → %s", UNIT(a)->meta.id, state_string_table[old_state], state_string_table[state]);
 180
 181         unit_notify(UNIT(a), state_translation_table[old_state], state_translation_table[state]);
 182 }
 183
 184 static void automount_dump(Unit *u, FILE *f, const char *prefix) {
 185         Automount *s = AUTOMOUNT(u);
 186
 187         assert(s);
 188
 189         fprintf(f,
 190                 "%sAutomount State: %s\n",
 191                 prefix, state_string_table[s->state]);
 192 }
 193
 194 static void automount_enter_dead(Automount *a, bool success) {
 195         assert(a);
 196
 197         if (!success)
 198                 a->failure = true;
 199
 200         automount_set_state(a, a->failure ? AUTOMOUNT_MAINTAINANCE : AUTOMOUNT_DEAD);
 201 }
 202
 203 static int open_dev_autofs(Manager *m) {
 204         struct autofs_dev_ioctl param;
 205
 206         assert(m);
 207
 208         if (m->dev_autofs_fd >= 0)
 209                 return m->dev_autofs_fd;
 210
 211         if ((m->dev_autofs_fd = open("/dev/autofs", O_RDONLY)) < 0) {
 212                 log_error("Failed to open /dev/autofs: %s", strerror(errno));
 213                 return -errno;
 214         }
 215
 216         init_autofs_dev_ioctl(&param);
 217         if (ioctl(m->dev_autofs_fd, AUTOFS_DEV_IOCTL_VERSION, &param) < 0) {
 218                 close_nointr_nofail(m->dev_autofs_fd);
 219                 m->dev_autofs_fd = -1;
 220                 return -errno;
 221         }
 222
 223         log_debug("Autofs kernel version %i.%i", param.ver_major, param.ver_minor);
 224
 225         return m->dev_autofs_fd;
 226 }
 227
 228 static int open_ioctl_fd(int dev_autofs_fd, const char *where, dev_t devid) {
 229         struct autofs_dev_ioctl *param;
 230         size_t l;
 231         int r;
 232
 233         assert(dev_autofs_fd >= 0);
 234         assert(where);
 235
 236         l = sizeof(struct autofs_dev_ioctl) + strlen(where) + 1;
 237
 238         if (!(param = malloc(l)))
 239                 return -ENOMEM;
 240
 241         init_autofs_dev_ioctl(param);
 242         param->size = l;
 243         param->ioctlfd = -1;
 244         param->openmount.devid = devid;
 245         strcpy(param->path, where);
 246
 247         if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_OPENMOUNT, param) < 0) {
 248                 r = -errno;
 249                 goto finish;
 250         }
 251
 252         if (param->ioctlfd < 0) {
 253                 r = -EIO;
 254                 goto finish;
 255         }
 256
 257         r = param->ioctlfd;
 258
 259 finish:
 260         free(param);
 261         return r;
 262 }
 263
 264 static int autofs_protocol(int dev_autofs_fd, int ioctl_fd) {
 265         uint32_t major, minor;
 266         struct autofs_dev_ioctl param;
 267
 268         assert(dev_autofs_fd >= 0);
 269         assert(ioctl_fd >= 0);
 270
 271         init_autofs_dev_ioctl(&param);
 272         param.ioctlfd = ioctl_fd;
 273
 274         if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_PROTOVER, &param) < 0)
 275                 return -errno;
 276
 277         major = param.protover.version;
 278
 279         init_autofs_dev_ioctl(&param);
 280         param.ioctlfd = ioctl_fd;
 281
 282         if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_PROTOSUBVER, &param) < 0)
 283                 return -errno;
 284
 285         minor = param.protosubver.sub_version;
 286
 287         log_debug("Autofs protocol version %i.%i", major, minor);
 288         return 0;
 289 }
 290
 291 static int autofs_set_timeout(int dev_autofs_fd, int ioctl_fd, time_t sec) {
 292         struct autofs_dev_ioctl param;
 293
 294         assert(dev_autofs_fd >= 0);
 295         assert(ioctl_fd >= 0);
 296
 297         init_autofs_dev_ioctl(&param);
 298         param.ioctlfd = ioctl_fd;
 299         param.timeout.timeout = sec;
 300
 301         if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_TIMEOUT, &param) < 0)
 302                 return -errno;
 303
 304         return 0;
 305 }
 306
 307 static int autofs_send_ready(int dev_autofs_fd, int ioctl_fd, uint32_t token, int status) {
 308         struct autofs_dev_ioctl param;
 309
 310         assert(dev_autofs_fd >= 0);
 311         assert(ioctl_fd >= 0);
 312
 313         init_autofs_dev_ioctl(&param);
 314         param.ioctlfd = ioctl_fd;
 315
 316         if (status) {
 317                 param.fail.token = token;
 318                 param.fail.status = status;
 319         } else
 320                 param.ready.token = token;
 321
 322         if (ioctl(dev_autofs_fd, status ? AUTOFS_DEV_IOCTL_FAIL : AUTOFS_DEV_IOCTL_READY, &param) < 0)
 323                 return -errno;
 324
 325         return 0;
 326 }
 327
 328 int automount_send_ready(Automount *a, int status) {
 329         int ioctl_fd, r;
 330         unsigned token;
 331
 332         assert(a);
 333         assert(status <= 0);
 334
 335         if (set_isempty(a->tokens))
 336                 return 0;
 337
 338         if ((ioctl_fd = open_ioctl_fd(UNIT(a)->meta.manager->dev_autofs_fd, a->where, a->dev_id)) < 0) {
 339                 r = ioctl_fd;
 340                 goto fail;
 341         }
 342
 343         if (status)
 344                 log_debug("Sending failure: %s", strerror(-status));
 345         else
 346                 log_debug("Sending success.");
 347
 348         /* Autofs thankfully does not hand out 0 as a token */
 349         while ((token = PTR_TO_UINT(set_steal_first(a->tokens)))) {
 350                 int k;
 351
 352                 /* Autofs fun fact II:
 353                  *
 354                  * if you pass a positive status code here, the kernel will
 355                  * freeze! Yay! */
 356
 357                 if ((k = autofs_send_ready(UNIT(a)->meta.manager->dev_autofs_fd,
 358                                            ioctl_fd,
 359                                            token,
 360                                            status)) < 0)
 361                         r = k;
 362         }
 363
 364         r = 0;
 365
 366 fail:
 367         if (ioctl_fd >= 0)
 368                 close_nointr_nofail(ioctl_fd);
 369
 370         return r;
 371 }
 372
 373 static void automount_enter_waiting(Automount *a) {
 374         int p[2] = { -1, -1 };
 375         char name[32], options[128];
 376         bool mounted = false;
 377         int r, ioctl_fd = -1, dev_autofs_fd;
 378         struct stat st;
 379
 380         assert(a);
 381         assert(a->pipe_fd < 0);
 382         assert(a->where);
 383
 384         if (a->tokens)
 385                 set_clear(a->tokens);
 386         else if (!(a->tokens = set_new(trivial_hash_func, trivial_compare_func))) {
 387                 r = -ENOMEM;
 388                 goto fail;
 389         }
 390
 391         if ((dev_autofs_fd = open_dev_autofs(UNIT(a)->meta.manager)) < 0) {
 392                 r = dev_autofs_fd;
 393                 goto fail;
 394         }
 395
 396         /* We knowingly ignore the results of this call */
 397         mkdir_p(a->where, 0555);
 398
 399         if (pipe2(p, O_NONBLOCK) < 0) {
 400                 r = -errno;
 401                 goto fail;
 402         }
 403
 404         snprintf(options, sizeof(options), "fd=%i,pgrp=%u,minproto=5,maxproto=5,direct", p[1], (unsigned) getpgrp());
 405         char_array_0(options);
 406
 407         snprintf(name, sizeof(name), "systemd-%u", (unsigned) getpid());
 408         char_array_0(name);
 409
 410         if (mount(name, a->where, "autofs", 0, options) < 0) {
 411                 r = -errno;
 412                 goto fail;
 413         }
 414
 415         mounted = true;
 416
 417         close_nointr_nofail(p[1]);
 418         p[1] = -1;
 419
 420         if (stat(a->where, &st) < 0) {
 421                 r = -errno;
 422                 goto fail;
 423         }
 424
 425         if ((ioctl_fd = open_ioctl_fd(dev_autofs_fd, a->where, st.st_dev)) < 0) {
 426                 r = ioctl_fd;
 427                 goto fail;
 428         }
 429
 430         if ((r = autofs_protocol(dev_autofs_fd, ioctl_fd)) < 0)
 431                 goto fail;
 432
 433         if ((r = autofs_set_timeout(dev_autofs_fd, ioctl_fd, 300)) < 0)
 434                 goto fail;
 435
 436         /* Autofs fun fact:
 437          *
 438          * Unless we close the ioctl fd here, for some weird reason
 439          * the direct mount will not receive events from the
 440          * kernel. */
 441
 442         close_nointr_nofail(ioctl_fd);
 443         ioctl_fd = -1;
 444
 445         if ((r = unit_watch_fd(UNIT(a), p[0], EPOLLIN, &a->pipe_watch)) < 0)
 446                 goto fail;
 447
 448         a->pipe_fd = p[0];
 449         a->dev_id = st.st_dev;
 450
 451         automount_set_state(a, AUTOMOUNT_WAITING);
 452
 453         return;
 454
 455 fail:
 456         assert_se(close_pipe(p) == 0);
 457
 458         if (ioctl_fd >= 0)
 459                 close_nointr_nofail(ioctl_fd);
 460
 461         if (mounted)
 462                 repeat_unmout(a->where);
 463
 464         log_error("Failed to initialize automounter: %s", strerror(-r));
 465         automount_enter_dead(a, false);
 466 }
 467
 468 static void automount_enter_runnning(Automount *a) {
 469         int r;
 470         struct stat st;
 471
 472         assert(a);
 473         assert(a->mount);
 474
 475         /* Before we do anything, let's see if somebody is playing games with us? */
 476
 477         if (stat(a->where, &st) < 0) {
 478                 log_warning("%s failed stat automount point: %m", a->meta.id);
 479                 goto fail;
 480         }
 481
 482         if (!S_ISDIR(st.st_mode) || st.st_dev != a->dev_id)
 483                 log_info("%s's automount point already active?", a->meta.id);
 484         else if ((r = manager_add_job(UNIT(a)->meta.manager, JOB_START, UNIT(a->mount), JOB_REPLACE, true, NULL)) < 0) {
 485                 log_warning("%s failed to queue mount startup job: %s", a->meta.id, strerror(-r));
 486                 goto fail;
 487         }
 488
 489         automount_set_state(a, AUTOMOUNT_RUNNING);
 490         return;
 491
 492 fail:
 493         automount_enter_dead(a, false);
 494 }
 495
 496 static int automount_start(Unit *u) {
 497         Automount *a = AUTOMOUNT(u);
 498
 499         assert(a);
 500
 501         if (path_is_mount_point(a->where)) {
 502                 log_error("Path %s is already a mount point, refusing start for %s", a->where, u->meta.id);
 503                 return -EEXIST;
 504         }
 505
 506         assert(a->state == AUTOMOUNT_DEAD || a->state == AUTOMOUNT_MAINTAINANCE);
 507
 508         a->failure = false;
 509         automount_enter_waiting(a);
 510         return 0;
 511 }
 512
 513 static int automount_stop(Unit *u) {
 514         Automount *a = AUTOMOUNT(u);
 515
 516         assert(a);
 517
 518         assert(a->state == AUTOMOUNT_WAITING || a->state == AUTOMOUNT_RUNNING);
 519
 520         automount_enter_dead(a, true);
 521         return 0;
 522 }
 523
 524 static UnitActiveState automount_active_state(Unit *u) {
 525
 526         return state_translation_table[AUTOMOUNT(u)->state];
 527 }
 528
 529 static const char *automount_sub_state_to_string(Unit *u) {
 530         assert(u);
 531
 532         return state_string_table[AUTOMOUNT(u)->state];
 533 }
 534
 535 static void automount_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 536         union autofs_v5_packet_union packet;
 537         ssize_t l;
 538         int r;
 539
 540         Automount *a = AUTOMOUNT(u);
 541
 542         assert(a);
 543         assert(fd == a->pipe_fd);
 544
 545         if (events != EPOLLIN) {
 546                 log_error("Got invalid poll event on pipe.");
 547                 goto fail;
 548         }
 549
 550         if ((l = loop_read(a->pipe_fd, &packet, sizeof(packet))) != sizeof(packet)) {
 551                 log_error("Invalid read from pipe: %s", l < 0 ? strerror(-l) : "short read");
 552                 goto fail;
 553         }
 554
 555         switch (packet.hdr.type) {
 556
 557         case autofs_ptype_missing_direct:
 558                 log_debug("Got direct mount request for %s", packet.v5_packet.name);
 559
 560                 if ((r = set_put(a->tokens, UINT_TO_PTR(packet.v5_packet.wait_queue_token))) < 0) {
 561                         log_error("Failed to remember token: %s", strerror(-r));
 562                         goto fail;
 563                 }
 564
 565                 automount_enter_runnning(a);
 566                 break;
 567
 568         default:
 569                 log_error("Received unknown automount request %i", packet.hdr.type);
 570                 break;
 571         }
 572
 573         return;
 574
 575 fail:
 576         automount_enter_dead(a, false);
 577 }
 578
 579 static void automount_shutdown(Manager *m) {
 580         assert(m);
 581
 582         if (m->dev_autofs_fd >= 0)
 583                 close_nointr_nofail(m->dev_autofs_fd);
 584 }
 585
 586 const UnitVTable automount_vtable = {
 587         .suffix = ".automount",
 588
 589         .no_alias = true,
 590         .no_instances = true,
 591
 592         .init = automount_init,
 593         .load = automount_load,
 594         .done = automount_done,
 595
 596         .dump = automount_dump,
 597
 598         .start = automount_start,
 599         .stop = automount_stop,
 600
 601         .active_state = automount_active_state,
 602         .sub_state_to_string = automount_sub_state_to_string,
 603
 604         .fd_event = automount_fd_event,
 605
 606         .bus_message_handler = bus_automount_message_handler,
 607
 608         .shutdown = automount_shutdown
 609 };