src/login/logind-session-device.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2013 David Herrmann
   6 ***/
   7
   8 #include <fcntl.h>
   9 #include <linux/input.h>
  10 #include <string.h>
  11 #include <sys/ioctl.h>
  12 #include <sys/types.h>
  13
  14 #include "libudev.h"
  15
  16 #include "alloc-util.h"
  17 #include "bus-util.h"
  18 #include "fd-util.h"
  19 #include "logind-session-device.h"
  20 #include "missing.h"
  21 #include "parse-util.h"
  22 #include "sd-daemon.h"
  23 #include "util.h"
  24
  25 enum SessionDeviceNotifications {
  26         SESSION_DEVICE_RESUME,
  27         SESSION_DEVICE_TRY_PAUSE,
  28         SESSION_DEVICE_PAUSE,
  29         SESSION_DEVICE_RELEASE,
  30 };
  31
  32 static int session_device_notify(SessionDevice *sd, enum SessionDeviceNotifications type) {
  33         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  34         _cleanup_free_ char *path = NULL;
  35         const char *t = NULL;
  36         uint32_t major, minor;
  37         int r;
  38
  39         assert(sd);
  40
  41         major = major(sd->dev);
  42         minor = minor(sd->dev);
  43
  44         if (!sd->session->controller)
  45                 return 0;
  46
  47         path = session_bus_path(sd->session);
  48         if (!path)
  49                 return -ENOMEM;
  50
  51         r = sd_bus_message_new_signal(
  52                         sd->session->manager->bus,
  53                         &m, path,
  54                         "org.freedesktop.login1.Session",
  55                         (type == SESSION_DEVICE_RESUME) ? "ResumeDevice" : "PauseDevice");
  56         if (!m)
  57                 return r;
  58
  59         r = sd_bus_message_set_destination(m, sd->session->controller);
  60         if (r < 0)
  61                 return r;
  62
  63         switch (type) {
  64
  65         case SESSION_DEVICE_RESUME:
  66                 r = sd_bus_message_append(m, "uuh", major, minor, sd->fd);
  67                 if (r < 0)
  68                         return r;
  69                 break;
  70
  71         case SESSION_DEVICE_TRY_PAUSE:
  72                 t = "pause";
  73                 break;
  74
  75         case SESSION_DEVICE_PAUSE:
  76                 t = "force";
  77                 break;
  78
  79         case SESSION_DEVICE_RELEASE:
  80                 t = "gone";
  81                 break;
  82
  83         default:
  84                 return -EINVAL;
  85         }
  86
  87         if (t) {
  88                 r = sd_bus_message_append(m, "uus", major, minor, t);
  89                 if (r < 0)
  90                         return r;
  91         }
  92
  93         return sd_bus_send(sd->session->manager->bus, m, NULL);
  94 }
  95
  96 static void sd_eviocrevoke(int fd) {
  97         static bool warned = false;
  98
  99         assert(fd >= 0);
 100
 101         if (ioctl(fd, EVIOCREVOKE, NULL) < 0) {
 102
 103                 if (errno == EINVAL && !warned) {
 104                         log_warning_errno(errno, "Kernel does not support evdev-revocation: %m");
 105                         warned = true;
 106                 }
 107         }
 108 }
 109
 110 static int sd_drmsetmaster(int fd) {
 111         assert(fd >= 0);
 112
 113         if (ioctl(fd, DRM_IOCTL_SET_MASTER, 0) < 0)
 114                 return -errno;
 115
 116         return 0;
 117 }
 118
 119 static int sd_drmdropmaster(int fd) {
 120         assert(fd >= 0);
 121
 122         if (ioctl(fd, DRM_IOCTL_DROP_MASTER, 0) < 0)
 123                 return -errno;
 124
 125         return 0;
 126 }
 127
 128 static int session_device_open(SessionDevice *sd, bool active) {
 129         int fd, r;
 130
 131         assert(sd);
 132         assert(sd->type != DEVICE_TYPE_UNKNOWN);
 133         assert(sd->node);
 134
 135         /* open device and try to get an udev_device from it */
 136         fd = open(sd->node, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
 137         if (fd < 0)
 138                 return -errno;
 139
 140         switch (sd->type) {
 141
 142         case DEVICE_TYPE_DRM:
 143                 if (active) {
 144                         /* Weird legacy DRM semantics might return an error even though we're master. No way to detect
 145                          * that so fail at all times and let caller retry in inactive state. */
 146                         r = sd_drmsetmaster(fd);
 147                         if (r < 0) {
 148                                 close_nointr(fd);
 149                                 return r;
 150                         }
 151                 } else
 152                         /* DRM-Master is granted to the first user who opens a device automatically (ughh,
 153                          * racy!). Hence, we just drop DRM-Master in case we were the first. */
 154                         (void) sd_drmdropmaster(fd);
 155                 break;
 156
 157         case DEVICE_TYPE_EVDEV:
 158                 if (!active)
 159                         sd_eviocrevoke(fd);
 160                 break;
 161
 162         case DEVICE_TYPE_UNKNOWN:
 163         default:
 164                 /* fallback for devices wihout synchronizations */
 165                 break;
 166         }
 167
 168         return fd;
 169 }
 170
 171 static int session_device_start(SessionDevice *sd) {
 172         int r;
 173
 174         assert(sd);
 175         assert(session_is_active(sd->session));
 176
 177         if (sd->active)
 178                 return 0;
 179
 180         switch (sd->type) {
 181
 182         case DEVICE_TYPE_DRM:
 183                 if (sd->fd < 0) {
 184                         log_error("Failed to re-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
 185                         return -EBADF;
 186                 }
 187
 188                 /* Device is kept open. Simply call drmSetMaster() and hope there is no-one else. In case it fails, we
 189                  * keep the device paused. Maybe at some point we have a drmStealMaster(). */
 190                 r = sd_drmsetmaster(sd->fd);
 191                 if (r < 0)
 192                         return r;
 193                 break;
 194
 195         case DEVICE_TYPE_EVDEV:
 196                 /* Evdev devices are revoked while inactive. Reopen it and we are fine. */
 197                 r = session_device_open(sd, true);
 198                 if (r < 0)
 199                         return r;
 200
 201                 /* For evdev devices, the file descriptor might be left uninitialized. This might happen while resuming
 202                  * into a session and logind has been restarted right before. */
 203                 safe_close(sd->fd);
 204                 sd->fd = r;
 205                 break;
 206
 207         case DEVICE_TYPE_UNKNOWN:
 208         default:
 209                 /* fallback for devices without synchronizations */
 210                 break;
 211         }
 212
 213         sd->active = true;
 214         return 0;
 215 }
 216
 217 static void session_device_stop(SessionDevice *sd) {
 218         assert(sd);
 219
 220         if (!sd->active)
 221                 return;
 222
 223         switch (sd->type) {
 224
 225         case DEVICE_TYPE_DRM:
 226                 if (sd->fd < 0) {
 227                         log_error("Failed to de-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
 228                         return;
 229                 }
 230
 231                 /* On DRM devices we simply drop DRM-Master but keep it open.
 232                  * This allows the user to keep resources allocated. The
 233                  * CAP_SYS_ADMIN restriction to DRM-Master prevents users from
 234                  * circumventing this. */
 235                 sd_drmdropmaster(sd->fd);
 236                 break;
 237
 238         case DEVICE_TYPE_EVDEV:
 239                 /* Revoke access on evdev file-descriptors during deactivation.
 240                  * This will basically prevent any operations on the fd and
 241                  * cannot be undone. Good side is: it needs no CAP_SYS_ADMIN
 242                  * protection this way. */
 243                 sd_eviocrevoke(sd->fd);
 244                 break;
 245
 246         case DEVICE_TYPE_UNKNOWN:
 247         default:
 248                 /* fallback for devices without synchronization */
 249                 break;
 250         }
 251
 252         sd->active = false;
 253 }
 254
 255 static DeviceType detect_device_type(struct udev_device *dev) {
 256         const char *sysname, *subsystem;
 257         DeviceType type;
 258
 259         sysname = udev_device_get_sysname(dev);
 260         subsystem = udev_device_get_subsystem(dev);
 261         type = DEVICE_TYPE_UNKNOWN;
 262
 263         if (streq_ptr(subsystem, "drm")) {
 264                 if (startswith(sysname, "card"))
 265                         type = DEVICE_TYPE_DRM;
 266         } else if (streq_ptr(subsystem, "input")) {
 267                 if (startswith(sysname, "event"))
 268                         type = DEVICE_TYPE_EVDEV;
 269         }
 270
 271         return type;
 272 }
 273
 274 static int session_device_verify(SessionDevice *sd) {
 275         struct udev_device *dev, *p = NULL;
 276         const char *sp, *node;
 277         int r;
 278
 279         dev = udev_device_new_from_devnum(sd->session->manager->udev, 'c', sd->dev);
 280         if (!dev)
 281                 return -ENODEV;
 282
 283         sp = udev_device_get_syspath(dev);
 284         node = udev_device_get_devnode(dev);
 285         if (!node) {
 286                 r = -EINVAL;
 287                 goto err_dev;
 288         }
 289
 290         /* detect device type so we can find the correct sysfs parent */
 291         sd->type = detect_device_type(dev);
 292         if (sd->type == DEVICE_TYPE_UNKNOWN) {
 293                 r = -ENODEV;
 294                 goto err_dev;
 295         } else if (sd->type == DEVICE_TYPE_EVDEV) {
 296                 /* for evdev devices we need the parent node as device */
 297                 p = dev;
 298                 dev = udev_device_get_parent_with_subsystem_devtype(p, "input", NULL);
 299                 if (!dev) {
 300                         r = -ENODEV;
 301                         goto err_dev;
 302                 }
 303                 sp = udev_device_get_syspath(dev);
 304         } else if (sd->type != DEVICE_TYPE_DRM) {
 305                 /* Prevent opening unsupported devices. Especially devices of
 306                  * subsystem "input" must be opened via the evdev node as
 307                  * we require EVIOCREVOKE. */
 308                 r = -ENODEV;
 309                 goto err_dev;
 310         }
 311
 312         /* search for an existing seat device and return it if available */
 313         sd->device = hashmap_get(sd->session->manager->devices, sp);
 314         if (!sd->device) {
 315                 /* The caller might have gotten the udev event before we were
 316                  * able to process it. Hence, fake the "add" event and let the
 317                  * logind-manager handle the new device. */
 318                 r = manager_process_seat_device(sd->session->manager, dev);
 319                 if (r < 0)
 320                         goto err_dev;
 321
 322                 /* if it's still not available, then the device is invalid */
 323                 sd->device = hashmap_get(sd->session->manager->devices, sp);
 324                 if (!sd->device) {
 325                         r = -ENODEV;
 326                         goto err_dev;
 327                 }
 328         }
 329
 330         if (sd->device->seat != sd->session->seat) {
 331                 r = -EPERM;
 332                 goto err_dev;
 333         }
 334
 335         sd->node = strdup(node);
 336         if (!sd->node) {
 337                 r = -ENOMEM;
 338                 goto err_dev;
 339         }
 340
 341         r = 0;
 342 err_dev:
 343         udev_device_unref(p ? : dev);
 344         return r;
 345 }
 346
 347 int session_device_new(Session *s, dev_t dev, bool open_device, SessionDevice **out) {
 348         SessionDevice *sd;
 349         int r;
 350
 351         assert(s);
 352         assert(out);
 353
 354         if (!s->seat)
 355                 return -EPERM;
 356
 357         sd = new0(SessionDevice, 1);
 358         if (!sd)
 359                 return -ENOMEM;
 360
 361         sd->session = s;
 362         sd->dev = dev;
 363         sd->fd = -1;
 364         sd->type = DEVICE_TYPE_UNKNOWN;
 365
 366         r = session_device_verify(sd);
 367         if (r < 0)
 368                 goto error;
 369
 370         r = hashmap_put(s->devices, &sd->dev, sd);
 371         if (r < 0)
 372                 goto error;
 373
 374         if (open_device) {
 375                 /* Open the device for the first time. We need a valid fd to pass back
 376                  * to the caller. If the session is not active, this _might_ immediately
 377                  * revoke access and thus invalidate the fd. But this is still needed
 378                  * to pass a valid fd back. */
 379                 sd->active = session_is_active(s);
 380                 r = session_device_open(sd, sd->active);
 381                 if (r < 0) {
 382                         /* EINVAL _may_ mean a master is active; retry inactive */
 383                         if (sd->active && r == -EINVAL) {
 384                                 sd->active = false;
 385                                 r = session_device_open(sd, false);
 386                         }
 387                         if (r < 0)
 388                                 goto error;
 389                 }
 390                 sd->fd = r;
 391         }
 392
 393         LIST_PREPEND(sd_by_device, sd->device->session_devices, sd);
 394
 395         *out = sd;
 396         return 0;
 397
 398 error:
 399         hashmap_remove(s->devices, &sd->dev);
 400         free(sd->node);
 401         free(sd);
 402         return r;
 403 }
 404
 405 void session_device_free(SessionDevice *sd) {
 406         assert(sd);
 407
 408         /* Make sure to remove the pushed fd. */
 409         if (sd->pushed_fd) {
 410                 _cleanup_free_ char *m = NULL;
 411                 const char *id;
 412                 int r;
 413
 414                 /* Session ID does not contain separators. */
 415                 id = sd->session->id;
 416                 assert(*(id + strcspn(id, "-\n")) == '\0');
 417
 418                 r = asprintf(&m, "FDSTOREREMOVE=1\n"
 419                                  "FDNAME=session-%s-device-%u-%u\n",
 420                                  id, major(sd->dev), minor(sd->dev));
 421                 if (r >= 0)
 422                         (void) sd_notify(false, m);
 423         }
 424
 425         session_device_stop(sd);
 426         session_device_notify(sd, SESSION_DEVICE_RELEASE);
 427         safe_close(sd->fd);
 428
 429         LIST_REMOVE(sd_by_device, sd->device->session_devices, sd);
 430
 431         hashmap_remove(sd->session->devices, &sd->dev);
 432
 433         free(sd->node);
 434         free(sd);
 435 }
 436
 437 void session_device_complete_pause(SessionDevice *sd) {
 438         SessionDevice *iter;
 439         Iterator i;
 440
 441         if (!sd->active)
 442                 return;
 443
 444         session_device_stop(sd);
 445
 446         /* if not all devices are paused, wait for further completion events */
 447         HASHMAP_FOREACH(iter, sd->session->devices, i)
 448                 if (iter->active)
 449                         return;
 450
 451         /* complete any pending session switch */
 452         seat_complete_switch(sd->session->seat);
 453 }
 454
 455 void session_device_resume_all(Session *s) {
 456         SessionDevice *sd;
 457         Iterator i;
 458
 459         assert(s);
 460
 461         HASHMAP_FOREACH(sd, s->devices, i) {
 462                 if (sd->active)
 463                         continue;
 464
 465                 if (session_device_start(sd) < 0)
 466                         continue;
 467                 if (session_device_save(sd) < 0)
 468                         continue;
 469
 470                 session_device_notify(sd, SESSION_DEVICE_RESUME);
 471         }
 472 }
 473
 474 void session_device_pause_all(Session *s) {
 475         SessionDevice *sd;
 476         Iterator i;
 477
 478         assert(s);
 479
 480         HASHMAP_FOREACH(sd, s->devices, i) {
 481                 if (!sd->active)
 482                         continue;
 483
 484                 session_device_stop(sd);
 485                 session_device_notify(sd, SESSION_DEVICE_PAUSE);
 486         }
 487 }
 488
 489 unsigned int session_device_try_pause_all(Session *s) {
 490         unsigned num_pending = 0;
 491         SessionDevice *sd;
 492         Iterator i;
 493
 494         assert(s);
 495
 496         HASHMAP_FOREACH(sd, s->devices, i) {
 497                 if (!sd->active)
 498                         continue;
 499
 500                 session_device_notify(sd, SESSION_DEVICE_TRY_PAUSE);
 501                 num_pending++;
 502         }
 503
 504         return num_pending;
 505 }
 506
 507 int session_device_save(SessionDevice *sd) {
 508         _cleanup_free_ char *m = NULL;
 509         const char *id;
 510         int r;
 511
 512         assert(sd);
 513
 514         /* Store device fd in PID1. It will send it back to us on restart so revocation will continue to work. To make
 515          * things simple, send fds for all type of devices even if they don't support the revocation mechanism so we
 516          * don't have to handle them differently later.
 517          *
 518          * Note: for device supporting revocation, PID1 will drop a stored fd automatically if the corresponding device
 519          * is revoked. */
 520
 521         if (sd->pushed_fd)
 522                 return 0;
 523
 524         /* Session ID does not contain separators. */
 525         id = sd->session->id;
 526         assert(*(id + strcspn(id, "-\n")) == '\0');
 527
 528         r = asprintf(&m, "FDSTORE=1\n"
 529                          "FDNAME=session-%s-device-%u-%u\n",
 530                          id, major(sd->dev), minor(sd->dev));
 531         if (r < 0)
 532                 return r;
 533
 534         r = sd_pid_notify_with_fds(0, false, m, &sd->fd, 1);
 535         if (r < 0)
 536                 return r;
 537
 538         sd->pushed_fd = true;
 539         return 1;
 540 }
 541
 542 void session_device_attach_fd(SessionDevice *sd, int fd, bool active) {
 543         assert(fd >= 0);
 544         assert(sd);
 545         assert(sd->fd < 0);
 546         assert(!sd->active);
 547
 548         sd->fd = fd;
 549         sd->pushed_fd = true;
 550         sd->active = active;
 551 }