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