src/login/logind-session-device.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2013 David Herrmann
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <fcntl.h>
  21 #include <linux/input.h>
  22 #include <string.h>
  23 #include <sys/ioctl.h>
  24 #include <sys/types.h>
  25
  26 #include "libudev.h"
  27
  28 #include "alloc-util.h"
  29 #include "bus-util.h"
  30 #include "fd-util.h"
  31 #include "logind-session-device.h"
  32 #include "missing.h"
  33 #include "util.h"
  34
  35 enum SessionDeviceNotifications {
  36         SESSION_DEVICE_RESUME,
  37         SESSION_DEVICE_TRY_PAUSE,
  38         SESSION_DEVICE_PAUSE,
  39         SESSION_DEVICE_RELEASE,
  40 };
  41
  42 static int session_device_notify(SessionDevice *sd, enum SessionDeviceNotifications type) {
  43         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  44         _cleanup_free_ char *path = NULL;
  45         const char *t = NULL;
  46         uint32_t major, minor;
  47         int r;
  48
  49         assert(sd);
  50
  51         major = major(sd->dev);
  52         minor = minor(sd->dev);
  53
  54         if (!sd->session->controller)
  55                 return 0;
  56
  57         path = session_bus_path(sd->session);
  58         if (!path)
  59                 return -ENOMEM;
  60
  61         r = sd_bus_message_new_signal(
  62                         sd->session->manager->bus,
  63                         &m, path,
  64                         "org.freedesktop.login1.Session",
  65                         (type == SESSION_DEVICE_RESUME) ? "ResumeDevice" : "PauseDevice");
  66         if (!m)
  67                 return r;
  68
  69         r = sd_bus_message_set_destination(m, sd->session->controller);
  70         if (r < 0)
  71                 return r;
  72
  73         switch (type) {
  74         case SESSION_DEVICE_RESUME:
  75                 r = sd_bus_message_append(m, "uuh", major, minor, sd->fd);
  76                 if (r < 0)
  77                         return r;
  78                 break;
  79         case SESSION_DEVICE_TRY_PAUSE:
  80                 t = "pause";
  81                 break;
  82         case SESSION_DEVICE_PAUSE:
  83                 t = "force";
  84                 break;
  85         case SESSION_DEVICE_RELEASE:
  86                 t = "gone";
  87                 break;
  88         default:
  89                 return -EINVAL;
  90         }
  91
  92         if (t) {
  93                 r = sd_bus_message_append(m, "uus", major, minor, t);
  94                 if (r < 0)
  95                         return r;
  96         }
  97
  98         return sd_bus_send(sd->session->manager->bus, m, NULL);
  99 }
 100
 101 static int sd_eviocrevoke(int fd) {
 102         static bool warned;
 103         int r;
 104
 105         assert(fd >= 0);
 106
 107         r = ioctl(fd, EVIOCREVOKE, NULL);
 108         if (r < 0) {
 109                 r = -errno;
 110                 if (r == -EINVAL && !warned) {
 111                         warned = true;
 112                         log_warning("kernel does not support evdev-revocation");
 113                 }
 114         }
 115
 116         return 0;
 117 }
 118
 119 static int sd_drmsetmaster(int fd) {
 120         int r;
 121
 122         assert(fd >= 0);
 123
 124         r = ioctl(fd, DRM_IOCTL_SET_MASTER, 0);
 125         if (r < 0)
 126                 return -errno;
 127
 128         return 0;
 129 }
 130
 131 static int sd_drmdropmaster(int fd) {
 132         int r;
 133
 134         assert(fd >= 0);
 135
 136         r = ioctl(fd, DRM_IOCTL_DROP_MASTER, 0);
 137         if (r < 0)
 138                 return -errno;
 139
 140         return 0;
 141 }
 142
 143 static int session_device_open(SessionDevice *sd, bool active) {
 144         int fd, r;
 145
 146         assert(sd->type != DEVICE_TYPE_UNKNOWN);
 147
 148         /* open device and try to get an udev_device from it */
 149         fd = open(sd->node, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
 150         if (fd < 0)
 151                 return -errno;
 152
 153         switch (sd->type) {
 154         case DEVICE_TYPE_DRM:
 155                 if (active) {
 156                         /* Weird legacy DRM semantics might return an error
 157                          * even though we're master. No way to detect that so
 158                          * fail at all times and let caller retry in inactive
 159                          * state. */
 160                         r = sd_drmsetmaster(fd);
 161                         if (r < 0) {
 162                                 close_nointr(fd);
 163                                 return r;
 164                         }
 165                 } else {
 166                         /* DRM-Master is granted to the first user who opens a
 167                          * device automatically (ughh, racy!). Hence, we just
 168                          * drop DRM-Master in case we were the first. */
 169                         sd_drmdropmaster(fd);
 170                 }
 171                 break;
 172         case DEVICE_TYPE_EVDEV:
 173                 if (!active)
 174                         sd_eviocrevoke(fd);
 175                 break;
 176         case DEVICE_TYPE_UNKNOWN:
 177         default:
 178                 /* fallback for devices wihout synchronizations */
 179                 break;
 180         }
 181
 182         return fd;
 183 }
 184
 185 static int session_device_start(SessionDevice *sd) {
 186         int r;
 187
 188         assert(sd);
 189         assert(session_is_active(sd->session));
 190
 191         if (sd->active)
 192                 return 0;
 193
 194         switch (sd->type) {
 195         case DEVICE_TYPE_DRM:
 196                 /* Device is kept open. Simply call drmSetMaster() and hope
 197                  * there is no-one else. In case it fails, we keep the device
 198                  * paused. Maybe at some point we have a drmStealMaster(). */
 199                 r = sd_drmsetmaster(sd->fd);
 200                 if (r < 0)
 201                         return r;
 202                 break;
 203         case DEVICE_TYPE_EVDEV:
 204                 /* Evdev devices are revoked while inactive. Reopen it and we
 205                  * are fine. */
 206                 r = session_device_open(sd, true);
 207                 if (r < 0)
 208                         return r;
 209                 close_nointr(sd->fd);
 210                 sd->fd = r;
 211                 break;
 212         case DEVICE_TYPE_UNKNOWN:
 213         default:
 214                 /* fallback for devices wihout synchronizations */
 215                 break;
 216         }
 217
 218         sd->active = true;
 219         return 0;
 220 }
 221
 222 static void session_device_stop(SessionDevice *sd) {
 223         assert(sd);
 224
 225         if (!sd->active)
 226                 return;
 227
 228         switch (sd->type) {
 229         case DEVICE_TYPE_DRM:
 230                 /* On DRM devices we simply drop DRM-Master but keep it open.
 231                  * This allows the user to keep resources allocated. The
 232                  * CAP_SYS_ADMIN restriction to DRM-Master prevents users from
 233                  * circumventing this. */
 234                 sd_drmdropmaster(sd->fd);
 235                 break;
 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         case DEVICE_TYPE_UNKNOWN:
 244         default:
 245                 /* fallback for devices without synchronization */
 246                 break;
 247         }
 248
 249         sd->active = false;
 250 }
 251
 252 static DeviceType detect_device_type(struct udev_device *dev) {
 253         const char *sysname, *subsystem;
 254         DeviceType type;
 255
 256         sysname = udev_device_get_sysname(dev);
 257         subsystem = udev_device_get_subsystem(dev);
 258         type = DEVICE_TYPE_UNKNOWN;
 259
 260         if (streq_ptr(subsystem, "drm")) {
 261                 if (startswith(sysname, "card"))
 262                         type = DEVICE_TYPE_DRM;
 263         } else if (streq_ptr(subsystem, "input")) {
 264                 if (startswith(sysname, "event"))
 265                         type = DEVICE_TYPE_EVDEV;
 266         }
 267
 268         return type;
 269 }
 270
 271 static int session_device_verify(SessionDevice *sd) {
 272         struct udev_device *dev, *p = NULL;
 273         const char *sp, *node;
 274         int r;
 275
 276         dev = udev_device_new_from_devnum(sd->session->manager->udev, 'c', sd->dev);
 277         if (!dev)
 278                 return -ENODEV;
 279
 280         sp = udev_device_get_syspath(dev);
 281         node = udev_device_get_devnode(dev);
 282         if (!node) {
 283                 r = -EINVAL;
 284                 goto err_dev;
 285         }
 286
 287         /* detect device type so we can find the correct sysfs parent */
 288         sd->type = detect_device_type(dev);
 289         if (sd->type == DEVICE_TYPE_UNKNOWN) {
 290                 r = -ENODEV;
 291                 goto err_dev;
 292         } else if (sd->type == DEVICE_TYPE_EVDEV) {
 293                 /* for evdev devices we need the parent node as device */
 294                 p = dev;
 295                 dev = udev_device_get_parent_with_subsystem_devtype(p, "input", NULL);
 296                 if (!dev) {
 297                         r = -ENODEV;
 298                         goto err_dev;
 299                 }
 300                 sp = udev_device_get_syspath(dev);
 301         } else if (sd->type != DEVICE_TYPE_DRM) {
 302                 /* Prevent opening unsupported devices. Especially devices of
 303                  * subsystem "input" must be opened via the evdev node as
 304                  * we require EVIOCREVOKE. */
 305                 r = -ENODEV;
 306                 goto err_dev;
 307         }
 308
 309         /* search for an existing seat device and return it if available */
 310         sd->device = hashmap_get(sd->session->manager->devices, sp);
 311         if (!sd->device) {
 312                 /* The caller might have gotten the udev event before we were
 313                  * able to process it. Hence, fake the "add" event and let the
 314                  * logind-manager handle the new device. */
 315                 r = manager_process_seat_device(sd->session->manager, dev);
 316                 if (r < 0)
 317                         goto err_dev;
 318
 319                 /* if it's still not available, then the device is invalid */
 320                 sd->device = hashmap_get(sd->session->manager->devices, sp);
 321                 if (!sd->device) {
 322                         r = -ENODEV;
 323                         goto err_dev;
 324                 }
 325         }
 326
 327         if (sd->device->seat != sd->session->seat) {
 328                 r = -EPERM;
 329                 goto err_dev;
 330         }
 331
 332         sd->node = strdup(node);
 333         if (!sd->node) {
 334                 r = -ENOMEM;
 335                 goto err_dev;
 336         }
 337
 338         r = 0;
 339 err_dev:
 340         udev_device_unref(p ? : dev);
 341         return r;
 342 }
 343
 344 int session_device_new(Session *s, dev_t dev, SessionDevice **out) {
 345         SessionDevice *sd;
 346         int r;
 347
 348         assert(s);
 349         assert(out);
 350
 351         if (!s->seat)
 352                 return -EPERM;
 353
 354         sd = new0(SessionDevice, 1);
 355         if (!sd)
 356                 return -ENOMEM;
 357
 358         sd->session = s;
 359         sd->dev = dev;
 360         sd->fd = -1;
 361         sd->type = DEVICE_TYPE_UNKNOWN;
 362
 363         r = session_device_verify(sd);
 364         if (r < 0)
 365                 goto error;
 366
 367         r = hashmap_put(s->devices, &sd->dev, sd);
 368         if (r < 0) {
 369                 r = -ENOMEM;
 370                 goto error;
 371         }
 372
 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         LIST_PREPEND(sd_by_device, sd->device->session_devices, sd);
 391
 392         *out = sd;
 393         return 0;
 394
 395 error:
 396         hashmap_remove(s->devices, &sd->dev);
 397         free(sd->node);
 398         free(sd);
 399         return r;
 400 }
 401
 402 void session_device_free(SessionDevice *sd) {
 403         assert(sd);
 404
 405         session_device_stop(sd);
 406         session_device_notify(sd, SESSION_DEVICE_RELEASE);
 407         close_nointr(sd->fd);
 408
 409         LIST_REMOVE(sd_by_device, sd->device->session_devices, sd);
 410
 411         hashmap_remove(sd->session->devices, &sd->dev);
 412
 413         free(sd->node);
 414         free(sd);
 415 }
 416
 417 void session_device_complete_pause(SessionDevice *sd) {
 418         SessionDevice *iter;
 419         Iterator i;
 420
 421         if (!sd->active)
 422                 return;
 423
 424         session_device_stop(sd);
 425
 426         /* if not all devices are paused, wait for further completion events */
 427         HASHMAP_FOREACH(iter, sd->session->devices, i)
 428                 if (iter->active)
 429                         return;
 430
 431         /* complete any pending session switch */
 432         seat_complete_switch(sd->session->seat);
 433 }
 434
 435 void session_device_resume_all(Session *s) {
 436         SessionDevice *sd;
 437         Iterator i;
 438         int r;
 439
 440         assert(s);
 441
 442         HASHMAP_FOREACH(sd, s->devices, i) {
 443                 if (!sd->active) {
 444                         r = session_device_start(sd);
 445                         if (!r)
 446                                 session_device_notify(sd, SESSION_DEVICE_RESUME);
 447                 }
 448         }
 449 }
 450
 451 void session_device_pause_all(Session *s) {
 452         SessionDevice *sd;
 453         Iterator i;
 454
 455         assert(s);
 456
 457         HASHMAP_FOREACH(sd, s->devices, i) {
 458                 if (sd->active) {
 459                         session_device_stop(sd);
 460                         session_device_notify(sd, SESSION_DEVICE_PAUSE);
 461                 }
 462         }
 463 }
 464
 465 unsigned int session_device_try_pause_all(Session *s) {
 466         SessionDevice *sd;
 467         Iterator i;
 468         unsigned int num_pending = 0;
 469
 470         assert(s);
 471
 472         HASHMAP_FOREACH(sd, s->devices, i) {
 473                 if (sd->active) {
 474                         session_device_notify(sd, SESSION_DEVICE_TRY_PAUSE);
 475                         ++num_pending;
 476                 }
 477         }
 478
 479         return num_pending;
 480 }