src/login/logind-session-device.c

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