src/login/logind-session-device.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <fcntl.h>
   4 #include <linux/input.h>
   5 #include <string.h>
   6 #include <stdint.h>
   7 #include <sys/ioctl.h>
   8 #include <sys/types.h>
   9
  10 /* Old drm.h may needs to be included after stdint.h and sys/types.h */
  11 #include <drm/drm.h>
  12
  13 #include "sd-device.h"
  14
  15 #include "alloc-util.h"
  16 #include "bus-util.h"
  17 #include "fd-util.h"
  18 #include "logind-session-device.h"
  19 #include "missing.h"
  20 #include "parse-util.h"
  21 #include "sd-daemon.h"
  22 #include "util.h"
  23
  24 enum SessionDeviceNotifications {
  25         SESSION_DEVICE_RESUME,
  26         SESSION_DEVICE_TRY_PAUSE,
  27         SESSION_DEVICE_PAUSE,
  28         SESSION_DEVICE_RELEASE,
  29 };
  30
  31 static int session_device_notify(SessionDevice *sd, enum SessionDeviceNotifications type) {
  32         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  33         _cleanup_free_ char *path = NULL;
  34         const char *t = NULL;
  35         uint32_t major, minor;
  36         int r;
  37
  38         assert(sd);
  39
  40         major = major(sd->dev);
  41         minor = minor(sd->dev);
  42
  43         if (!sd->session->controller)
  44                 return 0;
  45
  46         path = session_bus_path(sd->session);
  47         if (!path)
  48                 return -ENOMEM;
  49
  50         r = sd_bus_message_new_signal(
  51                         sd->session->manager->bus,
  52                         &m, path,
  53                         "org.freedesktop.login1.Session",
  54                         (type == SESSION_DEVICE_RESUME) ? "ResumeDevice" : "PauseDevice");
  55         if (!m)
  56                 return r;
  57
  58         r = sd_bus_message_set_destination(m, sd->session->controller);
  59         if (r < 0)
  60                 return r;
  61
  62         switch (type) {
  63
  64         case SESSION_DEVICE_RESUME:
  65                 r = sd_bus_message_append(m, "uuh", major, minor, sd->fd);
  66                 if (r < 0)
  67                         return r;
  68                 break;
  69
  70         case SESSION_DEVICE_TRY_PAUSE:
  71                 t = "pause";
  72                 break;
  73
  74         case SESSION_DEVICE_PAUSE:
  75                 t = "force";
  76                 break;
  77
  78         case SESSION_DEVICE_RELEASE:
  79                 t = "gone";
  80                 break;
  81
  82         default:
  83                 return -EINVAL;
  84         }
  85
  86         if (t) {
  87                 r = sd_bus_message_append(m, "uus", major, minor, t);
  88                 if (r < 0)
  89                         return r;
  90         }
  91
  92         return sd_bus_send(sd->session->manager->bus, m, NULL);
  93 }
  94
  95 static void sd_eviocrevoke(int fd) {
  96         static bool warned = false;
  97
  98         assert(fd >= 0);
  99
 100         if (ioctl(fd, EVIOCREVOKE, NULL) < 0) {
 101
 102                 if (errno == EINVAL && !warned) {
 103                         log_warning_errno(errno, "Kernel does not support evdev-revocation: %m");
 104                         warned = true;
 105                 }
 106         }
 107 }
 108
 109 static int sd_drmsetmaster(int fd) {
 110         assert(fd >= 0);
 111
 112         if (ioctl(fd, DRM_IOCTL_SET_MASTER, 0) < 0)
 113                 return -errno;
 114
 115         return 0;
 116 }
 117
 118 static int sd_drmdropmaster(int fd) {
 119         assert(fd >= 0);
 120
 121         if (ioctl(fd, DRM_IOCTL_DROP_MASTER, 0) < 0)
 122                 return -errno;
 123
 124         return 0;
 125 }
 126
 127 static int session_device_open(SessionDevice *sd, bool active) {
 128         int fd, r;
 129
 130         assert(sd);
 131         assert(sd->type != DEVICE_TYPE_UNKNOWN);
 132         assert(sd->node);
 133
 134         /* open device and try to get an udev_device from it */
 135         fd = open(sd->node, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
 136         if (fd < 0)
 137                 return -errno;
 138
 139         switch (sd->type) {
 140
 141         case DEVICE_TYPE_DRM:
 142                 if (active) {
 143                         /* Weird legacy DRM semantics might return an error even though we're master. No way to detect
 144                          * that so fail at all times and let caller retry in inactive state. */
 145                         r = sd_drmsetmaster(fd);
 146                         if (r < 0) {
 147                                 close_nointr(fd);
 148                                 return r;
 149                         }
 150                 } else
 151                         /* DRM-Master is granted to the first user who opens a device automatically (ughh,
 152                          * racy!). Hence, we just drop DRM-Master in case we were the first. */
 153                         (void) sd_drmdropmaster(fd);
 154                 break;
 155
 156         case DEVICE_TYPE_EVDEV:
 157                 if (!active)
 158                         sd_eviocrevoke(fd);
 159                 break;
 160
 161         case DEVICE_TYPE_UNKNOWN:
 162         default:
 163                 /* fallback for devices wihout synchronizations */
 164                 break;
 165         }
 166
 167         return fd;
 168 }
 169
 170 static int session_device_start(SessionDevice *sd) {
 171         int r;
 172
 173         assert(sd);
 174         assert(session_is_active(sd->session));
 175
 176         if (sd->active)
 177                 return 0;
 178
 179         switch (sd->type) {
 180
 181         case DEVICE_TYPE_DRM:
 182                 if (sd->fd < 0)
 183                         return log_error_errno(SYNTHETIC_ERRNO(EBADF),
 184                                                "Failed to re-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
 185
 186                 /* Device is kept open. Simply call drmSetMaster() and hope there is no-one else. In case it fails, we
 187                  * keep the device paused. Maybe at some point we have a drmStealMaster(). */
 188                 r = sd_drmsetmaster(sd->fd);
 189                 if (r < 0)
 190                         return r;
 191                 break;
 192
 193         case DEVICE_TYPE_EVDEV:
 194                 /* Evdev devices are revoked while inactive. Reopen it and we are fine. */
 195                 r = session_device_open(sd, true);
 196                 if (r < 0)
 197                         return r;
 198
 199                 /* For evdev devices, the file descriptor might be left uninitialized. This might happen while resuming
 200                  * into a session and logind has been restarted right before. */
 201                 safe_close(sd->fd);
 202                 sd->fd = r;
 203                 break;
 204
 205         case DEVICE_TYPE_UNKNOWN:
 206         default:
 207                 /* fallback for devices without synchronizations */
 208                 break;
 209         }
 210
 211         sd->active = true;
 212         return 0;
 213 }
 214
 215 static void session_device_stop(SessionDevice *sd) {
 216         assert(sd);
 217
 218         if (!sd->active)
 219                 return;
 220
 221         switch (sd->type) {
 222
 223         case DEVICE_TYPE_DRM:
 224                 if (sd->fd < 0) {
 225                         log_error("Failed to de-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
 226                         return;
 227                 }
 228
 229                 /* On DRM devices we simply drop DRM-Master but keep it open.
 230                  * This allows the user to keep resources allocated. The
 231                  * CAP_SYS_ADMIN restriction to DRM-Master prevents users from
 232                  * circumventing this. */
 233                 sd_drmdropmaster(sd->fd);
 234                 break;
 235
 236         case DEVICE_TYPE_EVDEV:
 237                 /* Revoke access on evdev file-descriptors during deactivation.
 238                  * This will basically prevent any operations on the fd and
 239                  * cannot be undone. Good side is: it needs no CAP_SYS_ADMIN
 240                  * protection this way. */
 241                 sd_eviocrevoke(sd->fd);
 242                 break;
 243
 244         case DEVICE_TYPE_UNKNOWN:
 245         default:
 246                 /* fallback for devices without synchronization */
 247                 break;
 248         }
 249
 250         sd->active = false;
 251 }
 252
 253 static DeviceType detect_device_type(sd_device *dev) {
 254         const char *sysname, *subsystem;
 255         DeviceType type = DEVICE_TYPE_UNKNOWN;
 256
 257         if (sd_device_get_sysname(dev, &sysname) < 0 ||
 258             sd_device_get_subsystem(dev, &subsystem) < 0)
 259                 return type;
 260
 261         if (streq(subsystem, "drm")) {
 262                 if (startswith(sysname, "card"))
 263                         type = DEVICE_TYPE_DRM;
 264         } else if (streq(subsystem, "input")) {
 265                 if (startswith(sysname, "event"))
 266                         type = DEVICE_TYPE_EVDEV;
 267         }
 268
 269         return type;
 270 }
 271
 272 static int session_device_verify(SessionDevice *sd) {
 273         _cleanup_(sd_device_unrefp) sd_device *p = NULL;
 274         const char *sp, *node;
 275         sd_device *dev;
 276         int r;
 277
 278         r = sd_device_new_from_devnum(&p, 'c', sd->dev);
 279         if (r < 0)
 280                 return r;
 281
 282         dev = p;
 283
 284         if (sd_device_get_syspath(dev, &sp) < 0 ||
 285             sd_device_get_devname(dev, &node) < 0)
 286                 return -EINVAL;
 287
 288         /* detect device type so we can find the correct sysfs parent */
 289         sd->type = detect_device_type(dev);
 290         if (sd->type == DEVICE_TYPE_UNKNOWN)
 291                 return -ENODEV;
 292
 293         else if (sd->type == DEVICE_TYPE_EVDEV) {
 294                 /* for evdev devices we need the parent node as device */
 295                 if (sd_device_get_parent_with_subsystem_devtype(p, "input", NULL, &dev) < 0)
 296                         return -ENODEV;
 297                 if (sd_device_get_syspath(dev, &sp) < 0)
 298                         return -ENODEV;
 299
 300         } else if (sd->type != DEVICE_TYPE_DRM)
 301                 /* Prevent opening unsupported devices. Especially devices of
 302                  * subsystem "input" must be opened via the evdev node as
 303                  * we require EVIOCREVOKE. */
 304                 return -ENODEV;
 305
 306         /* search for an existing seat device and return it if available */
 307         sd->device = hashmap_get(sd->session->manager->devices, sp);
 308         if (!sd->device) {
 309                 /* The caller might have gotten the udev event before we were
 310                  * able to process it. Hence, fake the "add" event and let the
 311                  * logind-manager handle the new device. */
 312                 r = manager_process_seat_device(sd->session->manager, dev);
 313                 if (r < 0)
 314                         return r;
 315
 316                 /* if it's still not available, then the device is invalid */
 317                 sd->device = hashmap_get(sd->session->manager->devices, sp);
 318                 if (!sd->device)
 319                         return -ENODEV;
 320         }
 321
 322         if (sd->device->seat != sd->session->seat)
 323                 return -EPERM;
 324
 325         sd->node = strdup(node);
 326         if (!sd->node)
 327                 return -ENOMEM;
 328
 329         return 0;
 330 }
 331
 332 int session_device_new(Session *s, dev_t dev, bool open_device, SessionDevice **out) {
 333         SessionDevice *sd;
 334         int r;
 335
 336         assert(s);
 337         assert(out);
 338
 339         if (!s->seat)
 340                 return -EPERM;
 341
 342         sd = new0(SessionDevice, 1);
 343         if (!sd)
 344                 return -ENOMEM;
 345
 346         sd->session = s;
 347         sd->dev = dev;
 348         sd->fd = -1;
 349         sd->type = DEVICE_TYPE_UNKNOWN;
 350
 351         r = session_device_verify(sd);
 352         if (r < 0)
 353                 goto error;
 354
 355         r = hashmap_put(s->devices, &sd->dev, sd);
 356         if (r < 0)
 357                 goto error;
 358
 359         if (open_device) {
 360                 /* Open the device for the first time. We need a valid fd to pass back
 361                  * to the caller. If the session is not active, this _might_ immediately
 362                  * revoke access and thus invalidate the fd. But this is still needed
 363                  * to pass a valid fd back. */
 364                 sd->active = session_is_active(s);
 365                 r = session_device_open(sd, sd->active);
 366                 if (r < 0) {
 367                         /* EINVAL _may_ mean a master is active; retry inactive */
 368                         if (sd->active && r == -EINVAL) {
 369                                 sd->active = false;
 370                                 r = session_device_open(sd, false);
 371                         }
 372                         if (r < 0)
 373                                 goto error;
 374                 }
 375                 sd->fd = r;
 376         }
 377
 378         LIST_PREPEND(sd_by_device, sd->device->session_devices, sd);
 379
 380         *out = sd;
 381         return 0;
 382
 383 error:
 384         hashmap_remove(s->devices, &sd->dev);
 385         free(sd->node);
 386         free(sd);
 387         return r;
 388 }
 389
 390 void session_device_free(SessionDevice *sd) {
 391         assert(sd);
 392
 393         /* Make sure to remove the pushed fd. */
 394         if (sd->pushed_fd) {
 395                 _cleanup_free_ char *m = NULL;
 396                 const char *id;
 397                 int r;
 398
 399                 /* Session ID does not contain separators. */
 400                 id = sd->session->id;
 401                 assert(*(id + strcspn(id, "-\n")) == '\0');
 402
 403                 r = asprintf(&m, "FDSTOREREMOVE=1\n"
 404                                  "FDNAME=session-%s-device-%u-%u\n",
 405                                  id, major(sd->dev), minor(sd->dev));
 406                 if (r >= 0)
 407                         (void) sd_notify(false, m);
 408         }
 409
 410         session_device_stop(sd);
 411         session_device_notify(sd, SESSION_DEVICE_RELEASE);
 412         safe_close(sd->fd);
 413
 414         LIST_REMOVE(sd_by_device, sd->device->session_devices, sd);
 415
 416         hashmap_remove(sd->session->devices, &sd->dev);
 417
 418         free(sd->node);
 419         free(sd);
 420 }
 421
 422 void session_device_complete_pause(SessionDevice *sd) {
 423         SessionDevice *iter;
 424         Iterator i;
 425
 426         if (!sd->active)
 427                 return;
 428
 429         session_device_stop(sd);
 430
 431         /* if not all devices are paused, wait for further completion events */
 432         HASHMAP_FOREACH(iter, sd->session->devices, i)
 433                 if (iter->active)
 434                         return;
 435
 436         /* complete any pending session switch */
 437         seat_complete_switch(sd->session->seat);
 438 }
 439
 440 void session_device_resume_all(Session *s) {
 441         SessionDevice *sd;
 442         Iterator i;
 443
 444         assert(s);
 445
 446         HASHMAP_FOREACH(sd, s->devices, i) {
 447                 if (sd->active)
 448                         continue;
 449
 450                 if (session_device_start(sd) < 0)
 451                         continue;
 452                 if (session_device_save(sd) < 0)
 453                         continue;
 454
 455                 session_device_notify(sd, SESSION_DEVICE_RESUME);
 456         }
 457 }
 458
 459 void session_device_pause_all(Session *s) {
 460         SessionDevice *sd;
 461         Iterator i;
 462
 463         assert(s);
 464
 465         HASHMAP_FOREACH(sd, s->devices, i) {
 466                 if (!sd->active)
 467                         continue;
 468
 469                 session_device_stop(sd);
 470                 session_device_notify(sd, SESSION_DEVICE_PAUSE);
 471         }
 472 }
 473
 474 unsigned session_device_try_pause_all(Session *s) {
 475         unsigned num_pending = 0;
 476         SessionDevice *sd;
 477         Iterator i;
 478
 479         assert(s);
 480
 481         HASHMAP_FOREACH(sd, s->devices, i) {
 482                 if (!sd->active)
 483                         continue;
 484
 485                 session_device_notify(sd, SESSION_DEVICE_TRY_PAUSE);
 486                 num_pending++;
 487         }
 488
 489         return num_pending;
 490 }
 491
 492 int session_device_save(SessionDevice *sd) {
 493         _cleanup_free_ char *m = NULL;
 494         const char *id;
 495         int r;
 496
 497         assert(sd);
 498
 499         /* Store device fd in PID1. It will send it back to us on restart so revocation will continue to work. To make
 500          * things simple, send fds for all type of devices even if they don't support the revocation mechanism so we
 501          * don't have to handle them differently later.
 502          *
 503          * Note: for device supporting revocation, PID1 will drop a stored fd automatically if the corresponding device
 504          * is revoked. */
 505
 506         if (sd->pushed_fd)
 507                 return 0;
 508
 509         /* Session ID does not contain separators. */
 510         id = sd->session->id;
 511         assert(*(id + strcspn(id, "-\n")) == '\0');
 512
 513         r = asprintf(&m, "FDSTORE=1\n"
 514                          "FDNAME=session-%s-device-%u-%u\n",
 515                          id, major(sd->dev), minor(sd->dev));
 516         if (r < 0)
 517                 return r;
 518
 519         r = sd_pid_notify_with_fds(0, false, m, &sd->fd, 1);
 520         if (r < 0)
 521                 return r;
 522
 523         sd->pushed_fd = true;
 524         return 1;
 525 }
 526
 527 void session_device_attach_fd(SessionDevice *sd, int fd, bool active) {
 528         assert(fd >= 0);
 529         assert(sd);
 530         assert(sd->fd < 0);
 531         assert(!sd->active);
 532
 533         sd->fd = fd;
 534         sd->pushed_fd = true;
 535         sd->active = active;
 536 }