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 without 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                         return log_error_errno(SYNTHETIC_ERRNO(EBADF),
 180                                                "Failed to re-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
 181
 182                 /* Device is kept open. Simply call drmSetMaster() and hope there is no-one else. In case it fails, we
 183                  * keep the device paused. Maybe at some point we have a drmStealMaster(). */
 184                 r = sd_drmsetmaster(sd->fd);
 185                 if (r < 0)
 186                         return r;
 187                 break;
 188
 189         case DEVICE_TYPE_EVDEV:
 190                 /* Evdev devices are revoked while inactive. Reopen it and we are fine. */
 191                 r = session_device_open(sd, true);
 192                 if (r < 0)
 193                         return r;
 194
 195                 /* For evdev devices, the file descriptor might be left uninitialized. This might happen while resuming
 196                  * into a session and logind has been restarted right before. */
 197                 safe_close(sd->fd);
 198                 sd->fd = r;
 199                 break;
 200
 201         case DEVICE_TYPE_UNKNOWN:
 202         default:
 203                 /* fallback for devices without synchronizations */
 204                 break;
 205         }
 206
 207         sd->active = true;
 208         return 0;
 209 }
 210
 211 static void session_device_stop(SessionDevice *sd) {
 212         assert(sd);
 213
 214         if (!sd->active)
 215                 return;
 216
 217         switch (sd->type) {
 218
 219         case DEVICE_TYPE_DRM:
 220                 if (sd->fd < 0) {
 221                         log_error("Failed to de-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
 222                         return;
 223                 }
 224
 225                 /* On DRM devices we simply drop DRM-Master but keep it open.
 226                  * This allows the user to keep resources allocated. The
 227                  * CAP_SYS_ADMIN restriction to DRM-Master prevents users from
 228                  * circumventing this. */
 229                 sd_drmdropmaster(sd->fd);
 230                 break;
 231
 232         case DEVICE_TYPE_EVDEV:
 233                 /* Revoke access on evdev file-descriptors during deactivation.
 234                  * This will basically prevent any operations on the fd and
 235                  * cannot be undone. Good side is: it needs no CAP_SYS_ADMIN
 236                  * protection this way. */
 237                 sd_eviocrevoke(sd->fd);
 238                 break;
 239
 240         case DEVICE_TYPE_UNKNOWN:
 241         default:
 242                 /* fallback for devices without synchronization */
 243                 break;
 244         }
 245
 246         sd->active = false;
 247 }
 248
 249 static DeviceType detect_device_type(sd_device *dev) {
 250         const char *sysname, *subsystem;
 251         DeviceType type = DEVICE_TYPE_UNKNOWN;
 252
 253         if (sd_device_get_sysname(dev, &sysname) < 0 ||
 254             sd_device_get_subsystem(dev, &subsystem) < 0)
 255                 return type;
 256
 257         if (streq(subsystem, "drm")) {
 258                 if (startswith(sysname, "card"))
 259                         type = DEVICE_TYPE_DRM;
 260         } else if (streq(subsystem, "input")) {
 261                 if (startswith(sysname, "event"))
 262                         type = DEVICE_TYPE_EVDEV;
 263         }
 264
 265         return type;
 266 }
 267
 268 static int session_device_verify(SessionDevice *sd) {
 269         _cleanup_(sd_device_unrefp) sd_device *p = NULL;
 270         const char *sp, *node;
 271         sd_device *dev;
 272         int r;
 273
 274         r = sd_device_new_from_devnum(&p, 'c', sd->dev);
 275         if (r < 0)
 276                 return r;
 277
 278         dev = p;
 279
 280         if (sd_device_get_syspath(dev, &sp) < 0 ||
 281             sd_device_get_devname(dev, &node) < 0)
 282                 return -EINVAL;
 283
 284         /* detect device type so we can find the correct sysfs parent */
 285         sd->type = detect_device_type(dev);
 286         if (sd->type == DEVICE_TYPE_UNKNOWN)
 287                 return -ENODEV;
 288
 289         else if (sd->type == DEVICE_TYPE_EVDEV) {
 290                 /* for evdev devices we need the parent node as device */
 291                 if (sd_device_get_parent_with_subsystem_devtype(p, "input", NULL, &dev) < 0)
 292                         return -ENODEV;
 293                 if (sd_device_get_syspath(dev, &sp) < 0)
 294                         return -ENODEV;
 295
 296         } else if (sd->type != DEVICE_TYPE_DRM)
 297                 /* Prevent opening unsupported devices. Especially devices of
 298                  * subsystem "input" must be opened via the evdev node as
 299                  * we require EVIOCREVOKE. */
 300                 return -ENODEV;
 301
 302         /* search for an existing seat device and return it if available */
 303         sd->device = hashmap_get(sd->session->manager->devices, sp);
 304         if (!sd->device) {
 305                 /* The caller might have gotten the udev event before we were
 306                  * able to process it. Hence, fake the "add" event and let the
 307                  * logind-manager handle the new device. */
 308                 r = manager_process_seat_device(sd->session->manager, dev);
 309                 if (r < 0)
 310                         return r;
 311
 312                 /* if it's still not available, then the device is invalid */
 313                 sd->device = hashmap_get(sd->session->manager->devices, sp);
 314                 if (!sd->device)
 315                         return -ENODEV;
 316         }
 317
 318         if (sd->device->seat != sd->session->seat)
 319                 return -EPERM;
 320
 321         sd->node = strdup(node);
 322         if (!sd->node)
 323                 return -ENOMEM;
 324
 325         return 0;
 326 }
 327
 328 int session_device_new(Session *s, dev_t dev, bool open_device, SessionDevice **out) {
 329         SessionDevice *sd;
 330         int r;
 331
 332         assert(s);
 333         assert(out);
 334
 335         if (!s->seat)
 336                 return -EPERM;
 337
 338         sd = new0(SessionDevice, 1);
 339         if (!sd)
 340                 return -ENOMEM;
 341
 342         sd->session = s;
 343         sd->dev = dev;
 344         sd->fd = -1;
 345         sd->type = DEVICE_TYPE_UNKNOWN;
 346
 347         r = session_device_verify(sd);
 348         if (r < 0)
 349                 goto error;
 350
 351         r = hashmap_put(s->devices, &sd->dev, sd);
 352         if (r < 0)
 353                 goto error;
 354
 355         if (open_device) {
 356                 /* Open the device for the first time. We need a valid fd to pass back
 357                  * to the caller. If the session is not active, this _might_ immediately
 358                  * revoke access and thus invalidate the fd. But this is still needed
 359                  * to pass a valid fd back. */
 360                 sd->active = session_is_active(s);
 361                 r = session_device_open(sd, sd->active);
 362                 if (r < 0) {
 363                         /* EINVAL _may_ mean a master is active; retry inactive */
 364                         if (sd->active && r == -EINVAL) {
 365                                 sd->active = false;
 366                                 r = session_device_open(sd, false);
 367                         }
 368                         if (r < 0)
 369                                 goto error;
 370                 }
 371                 sd->fd = r;
 372         }
 373
 374         LIST_PREPEND(sd_by_device, sd->device->session_devices, sd);
 375
 376         *out = sd;
 377         return 0;
 378
 379 error:
 380         hashmap_remove(s->devices, &sd->dev);
 381         free(sd->node);
 382         free(sd);
 383         return r;
 384 }
 385
 386 void session_device_free(SessionDevice *sd) {
 387         assert(sd);
 388
 389         /* Make sure to remove the pushed fd. */
 390         if (sd->pushed_fd)
 391                 (void) sd_notifyf(false,
 392                                   "FDSTOREREMOVE=1\n"
 393                                   "FDNAME=session-%s-device-%u-%u",
 394                                   sd->session->id, major(sd->dev), minor(sd->dev));
 395
 396         session_device_stop(sd);
 397         session_device_notify(sd, SESSION_DEVICE_RELEASE);
 398         safe_close(sd->fd);
 399
 400         LIST_REMOVE(sd_by_device, sd->device->session_devices, sd);
 401
 402         hashmap_remove(sd->session->devices, &sd->dev);
 403
 404         free(sd->node);
 405         free(sd);
 406 }
 407
 408 void session_device_complete_pause(SessionDevice *sd) {
 409         SessionDevice *iter;
 410         Iterator i;
 411
 412         if (!sd->active)
 413                 return;
 414
 415         session_device_stop(sd);
 416
 417         /* if not all devices are paused, wait for further completion events */
 418         HASHMAP_FOREACH(iter, sd->session->devices, i)
 419                 if (iter->active)
 420                         return;
 421
 422         /* complete any pending session switch */
 423         seat_complete_switch(sd->session->seat);
 424 }
 425
 426 void session_device_resume_all(Session *s) {
 427         SessionDevice *sd;
 428         Iterator i;
 429
 430         assert(s);
 431
 432         HASHMAP_FOREACH(sd, s->devices, i) {
 433                 if (sd->active)
 434                         continue;
 435
 436                 if (session_device_start(sd) < 0)
 437                         continue;
 438                 if (session_device_save(sd) < 0)
 439                         continue;
 440
 441                 session_device_notify(sd, SESSION_DEVICE_RESUME);
 442         }
 443 }
 444
 445 void session_device_pause_all(Session *s) {
 446         SessionDevice *sd;
 447         Iterator i;
 448
 449         assert(s);
 450
 451         HASHMAP_FOREACH(sd, s->devices, i) {
 452                 if (!sd->active)
 453                         continue;
 454
 455                 session_device_stop(sd);
 456                 session_device_notify(sd, SESSION_DEVICE_PAUSE);
 457         }
 458 }
 459
 460 unsigned session_device_try_pause_all(Session *s) {
 461         unsigned num_pending = 0;
 462         SessionDevice *sd;
 463         Iterator i;
 464
 465         assert(s);
 466
 467         HASHMAP_FOREACH(sd, s->devices, i) {
 468                 if (!sd->active)
 469                         continue;
 470
 471                 session_device_notify(sd, SESSION_DEVICE_TRY_PAUSE);
 472                 num_pending++;
 473         }
 474
 475         return num_pending;
 476 }
 477
 478 int session_device_save(SessionDevice *sd) {
 479         _cleanup_free_ char *m = NULL;
 480         const char *id;
 481         int r;
 482
 483         assert(sd);
 484
 485         /* Store device fd in PID1. It will send it back to us on restart so revocation will continue to work. To make
 486          * things simple, send fds for all type of devices even if they don't support the revocation mechanism so we
 487          * don't have to handle them differently later.
 488          *
 489          * Note: for device supporting revocation, PID1 will drop a stored fd automatically if the corresponding device
 490          * is revoked. */
 491
 492         if (sd->pushed_fd)
 493                 return 0;
 494
 495         /* Session ID does not contain separators. */
 496         id = sd->session->id;
 497         assert(*(id + strcspn(id, "-\n")) == '\0');
 498
 499         r = asprintf(&m, "FDSTORE=1\n"
 500                          "FDNAME=session-%s-device-%u-%u\n",
 501                          id, major(sd->dev), minor(sd->dev));
 502         if (r < 0)
 503                 return r;
 504
 505         r = sd_pid_notify_with_fds(0, false, m, &sd->fd, 1);
 506         if (r < 0)
 507                 return r;
 508
 509         sd->pushed_fd = true;
 510         return 1;
 511 }
 512
 513 void session_device_attach_fd(SessionDevice *sd, int fd, bool active) {
 514         assert(fd >= 0);
 515         assert(sd);
 516         assert(sd->fd < 0);
 517         assert(!sd->active);
 518
 519         sd->fd = fd;
 520         sd->pushed_fd = true;
 521         sd->active = active;
 522 }