src/login/logind-session-device.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2013 David Herrmann
   4 ***/
   5
   6 #include <fcntl.h>
   7 #include <linux/input.h>
   8 #include <string.h>
   9 #include <sys/ioctl.h>
  10 #include <sys/types.h>
  11
  12 #include "libudev.h"
  13
  14 #include "alloc-util.h"
  15 #include "bus-util.h"
  16 #include "fd-util.h"
  17 #include "logind-session-device.h"
  18 #include "missing.h"
  19 #include "parse-util.h"
  20 #include "sd-daemon.h"
  21 #include "util.h"
  22
  23 enum SessionDeviceNotifications {
  24         SESSION_DEVICE_RESUME,
  25         SESSION_DEVICE_TRY_PAUSE,
  26         SESSION_DEVICE_PAUSE,
  27         SESSION_DEVICE_RELEASE,
  28 };
  29
  30 static int session_device_notify(SessionDevice *sd, enum SessionDeviceNotifications type) {
  31         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  32         _cleanup_free_ char *path = NULL;
  33         const char *t = NULL;
  34         uint32_t major, minor;
  35         int r;
  36
  37         assert(sd);
  38
  39         major = major(sd->dev);
  40         minor = minor(sd->dev);
  41
  42         if (!sd->session->controller)
  43                 return 0;
  44
  45         path = session_bus_path(sd->session);
  46         if (!path)
  47                 return -ENOMEM;
  48
  49         r = sd_bus_message_new_signal(
  50                         sd->session->manager->bus,
  51                         &m, path,
  52                         "org.freedesktop.login1.Session",
  53                         (type == SESSION_DEVICE_RESUME) ? "ResumeDevice" : "PauseDevice");
  54         if (!m)
  55                 return r;
  56
  57         r = sd_bus_message_set_destination(m, sd->session->controller);
  58         if (r < 0)
  59                 return r;
  60
  61         switch (type) {
  62
  63         case SESSION_DEVICE_RESUME:
  64                 r = sd_bus_message_append(m, "uuh", major, minor, sd->fd);
  65                 if (r < 0)
  66                         return r;
  67                 break;
  68
  69         case SESSION_DEVICE_TRY_PAUSE:
  70                 t = "pause";
  71                 break;
  72
  73         case SESSION_DEVICE_PAUSE:
  74                 t = "force";
  75                 break;
  76
  77         case SESSION_DEVICE_RELEASE:
  78                 t = "gone";
  79                 break;
  80
  81         default:
  82                 return -EINVAL;
  83         }
  84
  85         if (t) {
  86                 r = sd_bus_message_append(m, "uus", major, minor, t);
  87                 if (r < 0)
  88                         return r;
  89         }
  90
  91         return sd_bus_send(sd->session->manager->bus, m, NULL);
  92 }
  93
  94 static void sd_eviocrevoke(int fd) {
  95         static bool warned = false;
  96
  97         assert(fd >= 0);
  98
  99         if (ioctl(fd, EVIOCREVOKE, NULL) < 0) {
 100
 101                 if (errno == EINVAL && !warned) {
 102                         log_warning_errno(errno, "Kernel does not support evdev-revocation: %m");
 103                         warned = true;
 104                 }
 105         }
 106 }
 107
 108 static int sd_drmsetmaster(int fd) {
 109         assert(fd >= 0);
 110
 111         if (ioctl(fd, DRM_IOCTL_SET_MASTER, 0) < 0)
 112                 return -errno;
 113
 114         return 0;
 115 }
 116
 117 static int sd_drmdropmaster(int fd) {
 118         assert(fd >= 0);
 119
 120         if (ioctl(fd, DRM_IOCTL_DROP_MASTER, 0) < 0)
 121                 return -errno;
 122
 123         return 0;
 124 }
 125
 126 static int session_device_open(SessionDevice *sd, bool active) {
 127         int fd, r;
 128
 129         assert(sd);
 130         assert(sd->type != DEVICE_TYPE_UNKNOWN);
 131         assert(sd->node);
 132
 133         /* open device and try to get an udev_device from it */
 134         fd = open(sd->node, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
 135         if (fd < 0)
 136                 return -errno;
 137
 138         switch (sd->type) {
 139
 140         case DEVICE_TYPE_DRM:
 141                 if (active) {
 142                         /* Weird legacy DRM semantics might return an error even though we're master. No way to detect
 143                          * that so fail at all times and let caller retry in inactive state. */
 144                         r = sd_drmsetmaster(fd);
 145                         if (r < 0) {
 146                                 close_nointr(fd);
 147                                 return r;
 148                         }
 149                 } else
 150                         /* DRM-Master is granted to the first user who opens a device automatically (ughh,
 151                          * racy!). Hence, we just drop DRM-Master in case we were the first. */
 152                         (void) sd_drmdropmaster(fd);
 153                 break;
 154
 155         case DEVICE_TYPE_EVDEV:
 156                 if (!active)
 157                         sd_eviocrevoke(fd);
 158                 break;
 159
 160         case DEVICE_TYPE_UNKNOWN:
 161         default:
 162                 /* fallback for devices wihout synchronizations */
 163                 break;
 164         }
 165
 166         return fd;
 167 }
 168
 169 static int session_device_start(SessionDevice *sd) {
 170         int r;
 171
 172         assert(sd);
 173         assert(session_is_active(sd->session));
 174
 175         if (sd->active)
 176                 return 0;
 177
 178         switch (sd->type) {
 179
 180         case DEVICE_TYPE_DRM:
 181                 if (sd->fd < 0) {
 182                         log_error("Failed to re-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
 183                         return -EBADF;
 184                 }
 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(struct udev_device *dev) {
 254         const char *sysname, *subsystem;
 255         DeviceType type;
 256
 257         sysname = udev_device_get_sysname(dev);
 258         subsystem = udev_device_get_subsystem(dev);
 259         type = DEVICE_TYPE_UNKNOWN;
 260
 261         if (streq_ptr(subsystem, "drm")) {
 262                 if (startswith(sysname, "card"))
 263                         type = DEVICE_TYPE_DRM;
 264         } else if (streq_ptr(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         struct udev_device *dev, *p = NULL;
 274         const char *sp, *node;
 275         int r;
 276
 277         dev = udev_device_new_from_devnum(sd->session->manager->udev, 'c', sd->dev);
 278         if (!dev)
 279                 return -ENODEV;
 280
 281         sp = udev_device_get_syspath(dev);
 282         node = udev_device_get_devnode(dev);
 283         if (!node) {
 284                 r = -EINVAL;
 285                 goto err_dev;
 286         }
 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                 r = -ENODEV;
 292                 goto err_dev;
 293         } else if (sd->type == DEVICE_TYPE_EVDEV) {
 294                 /* for evdev devices we need the parent node as device */
 295                 p = dev;
 296                 dev = udev_device_get_parent_with_subsystem_devtype(p, "input", NULL);
 297                 if (!dev) {
 298                         r = -ENODEV;
 299                         goto err_dev;
 300                 }
 301                 sp = udev_device_get_syspath(dev);
 302         } else if (sd->type != DEVICE_TYPE_DRM) {
 303                 /* Prevent opening unsupported devices. Especially devices of
 304                  * subsystem "input" must be opened via the evdev node as
 305                  * we require EVIOCREVOKE. */
 306                 r = -ENODEV;
 307                 goto err_dev;
 308         }
 309
 310         /* search for an existing seat device and return it if available */
 311         sd->device = hashmap_get(sd->session->manager->devices, sp);
 312         if (!sd->device) {
 313                 /* The caller might have gotten the udev event before we were
 314                  * able to process it. Hence, fake the "add" event and let the
 315                  * logind-manager handle the new device. */
 316                 r = manager_process_seat_device(sd->session->manager, dev);
 317                 if (r < 0)
 318                         goto err_dev;
 319
 320                 /* if it's still not available, then the device is invalid */
 321                 sd->device = hashmap_get(sd->session->manager->devices, sp);
 322                 if (!sd->device) {
 323                         r = -ENODEV;
 324                         goto err_dev;
 325                 }
 326         }
 327
 328         if (sd->device->seat != sd->session->seat) {
 329                 r = -EPERM;
 330                 goto err_dev;
 331         }
 332
 333         sd->node = strdup(node);
 334         if (!sd->node) {
 335                 r = -ENOMEM;
 336                 goto err_dev;
 337         }
 338
 339         r = 0;
 340 err_dev:
 341         udev_device_unref(p ? : dev);
 342         return r;
 343 }
 344
 345 int session_device_new(Session *s, dev_t dev, bool open_device, SessionDevice **out) {
 346         SessionDevice *sd;
 347         int r;
 348
 349         assert(s);
 350         assert(out);
 351
 352         if (!s->seat)
 353                 return -EPERM;
 354
 355         sd = new0(SessionDevice, 1);
 356         if (!sd)
 357                 return -ENOMEM;
 358
 359         sd->session = s;
 360         sd->dev = dev;
 361         sd->fd = -1;
 362         sd->type = DEVICE_TYPE_UNKNOWN;
 363
 364         r = session_device_verify(sd);
 365         if (r < 0)
 366                 goto error;
 367
 368         r = hashmap_put(s->devices, &sd->dev, sd);
 369         if (r < 0)
 370                 goto error;
 371
 372         if (open_device) {
 373                 /* Open the device for the first time. We need a valid fd to pass back
 374                  * to the caller. If the session is not active, this _might_ immediately
 375                  * revoke access and thus invalidate the fd. But this is still needed
 376                  * to pass a valid fd back. */
 377                 sd->active = session_is_active(s);
 378                 r = session_device_open(sd, sd->active);
 379                 if (r < 0) {
 380                         /* EINVAL _may_ mean a master is active; retry inactive */
 381                         if (sd->active && r == -EINVAL) {
 382                                 sd->active = false;
 383                                 r = session_device_open(sd, false);
 384                         }
 385                         if (r < 0)
 386                                 goto error;
 387                 }
 388                 sd->fd = r;
 389         }
 390
 391         LIST_PREPEND(sd_by_device, sd->device->session_devices, sd);
 392
 393         *out = sd;
 394         return 0;
 395
 396 error:
 397         hashmap_remove(s->devices, &sd->dev);
 398         free(sd->node);
 399         free(sd);
 400         return r;
 401 }
 402
 403 void session_device_free(SessionDevice *sd) {
 404         assert(sd);
 405
 406         /* Make sure to remove the pushed fd. */
 407         if (sd->pushed_fd) {
 408                 _cleanup_free_ char *m = NULL;
 409                 const char *id;
 410                 int r;
 411
 412                 /* Session ID does not contain separators. */
 413                 id = sd->session->id;
 414                 assert(*(id + strcspn(id, "-\n")) == '\0');
 415
 416                 r = asprintf(&m, "FDSTOREREMOVE=1\n"
 417                                  "FDNAME=session-%s-device-%u-%u\n",
 418                                  id, major(sd->dev), minor(sd->dev));
 419                 if (r >= 0)
 420                         (void) sd_notify(false, m);
 421         }
 422
 423         session_device_stop(sd);
 424         session_device_notify(sd, SESSION_DEVICE_RELEASE);
 425         safe_close(sd->fd);
 426
 427         LIST_REMOVE(sd_by_device, sd->device->session_devices, sd);
 428
 429         hashmap_remove(sd->session->devices, &sd->dev);
 430
 431         free(sd->node);
 432         free(sd);
 433 }
 434
 435 void session_device_complete_pause(SessionDevice *sd) {
 436         SessionDevice *iter;
 437         Iterator i;
 438
 439         if (!sd->active)
 440                 return;
 441
 442         session_device_stop(sd);
 443
 444         /* if not all devices are paused, wait for further completion events */
 445         HASHMAP_FOREACH(iter, sd->session->devices, i)
 446                 if (iter->active)
 447                         return;
 448
 449         /* complete any pending session switch */
 450         seat_complete_switch(sd->session->seat);
 451 }
 452
 453 void session_device_resume_all(Session *s) {
 454         SessionDevice *sd;
 455         Iterator i;
 456
 457         assert(s);
 458
 459         HASHMAP_FOREACH(sd, s->devices, i) {
 460                 if (sd->active)
 461                         continue;
 462
 463                 if (session_device_start(sd) < 0)
 464                         continue;
 465                 if (session_device_save(sd) < 0)
 466                         continue;
 467
 468                 session_device_notify(sd, SESSION_DEVICE_RESUME);
 469         }
 470 }
 471
 472 void session_device_pause_all(Session *s) {
 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_stop(sd);
 483                 session_device_notify(sd, SESSION_DEVICE_PAUSE);
 484         }
 485 }
 486
 487 unsigned int session_device_try_pause_all(Session *s) {
 488         unsigned num_pending = 0;
 489         SessionDevice *sd;
 490         Iterator i;
 491
 492         assert(s);
 493
 494         HASHMAP_FOREACH(sd, s->devices, i) {
 495                 if (!sd->active)
 496                         continue;
 497
 498                 session_device_notify(sd, SESSION_DEVICE_TRY_PAUSE);
 499                 num_pending++;
 500         }
 501
 502         return num_pending;
 503 }
 504
 505 int session_device_save(SessionDevice *sd) {
 506         _cleanup_free_ char *m = NULL;
 507         const char *id;
 508         int r;
 509
 510         assert(sd);
 511
 512         /* Store device fd in PID1. It will send it back to us on restart so revocation will continue to work. To make
 513          * things simple, send fds for all type of devices even if they don't support the revocation mechanism so we
 514          * don't have to handle them differently later.
 515          *
 516          * Note: for device supporting revocation, PID1 will drop a stored fd automatically if the corresponding device
 517          * is revoked. */
 518
 519         if (sd->pushed_fd)
 520                 return 0;
 521
 522         /* Session ID does not contain separators. */
 523         id = sd->session->id;
 524         assert(*(id + strcspn(id, "-\n")) == '\0');
 525
 526         r = asprintf(&m, "FDSTORE=1\n"
 527                          "FDNAME=session-%s-device-%u-%u\n",
 528                          id, major(sd->dev), minor(sd->dev));
 529         if (r < 0)
 530                 return r;
 531
 532         r = sd_pid_notify_with_fds(0, false, m, &sd->fd, 1);
 533         if (r < 0)
 534                 return r;
 535
 536         sd->pushed_fd = true;
 537         return 1;
 538 }
 539
 540 void session_device_attach_fd(SessionDevice *sd, int fd, bool active) {
 541         assert(fd >= 0);
 542         assert(sd);
 543         assert(sd->fd < 0);
 544         assert(!sd->active);
 545
 546         sd->fd = fd;
 547         sd->pushed_fd = true;
 548         sd->active = active;
 549 }