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/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
Copyright 2013 David Herrmann
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <fcntl.h>
#include <linux/input.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include "libudev.h"
#include "alloc-util.h"
#include "bus-util.h"
#include "fd-util.h"
#include "logind-session-device.h"
#include "missing.h"
#include "parse-util.h"
#include "sd-daemon.h"
#include "util.h"
enum SessionDeviceNotifications {
SESSION_DEVICE_RESUME,
SESSION_DEVICE_TRY_PAUSE,
SESSION_DEVICE_PAUSE,
SESSION_DEVICE_RELEASE,
};
static int session_device_notify(SessionDevice *sd, enum SessionDeviceNotifications type) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
_cleanup_free_ char *path = NULL;
const char *t = NULL;
uint32_t major, minor;
int r;
assert(sd);
major = major(sd->dev);
minor = minor(sd->dev);
if (!sd->session->controller)
return 0;
path = session_bus_path(sd->session);
if (!path)
return -ENOMEM;
r = sd_bus_message_new_signal(
sd->session->manager->bus,
&m, path,
"org.freedesktop.login1.Session",
(type == SESSION_DEVICE_RESUME) ? "ResumeDevice" : "PauseDevice");
if (!m)
return r;
r = sd_bus_message_set_destination(m, sd->session->controller);
if (r < 0)
return r;
switch (type) {
case SESSION_DEVICE_RESUME:
r = sd_bus_message_append(m, "uuh", major, minor, sd->fd);
if (r < 0)
return r;
break;
case SESSION_DEVICE_TRY_PAUSE:
t = "pause";
break;
case SESSION_DEVICE_PAUSE:
t = "force";
break;
case SESSION_DEVICE_RELEASE:
t = "gone";
break;
default:
return -EINVAL;
}
if (t) {
r = sd_bus_message_append(m, "uus", major, minor, t);
if (r < 0)
return r;
}
return sd_bus_send(sd->session->manager->bus, m, NULL);
}
static void sd_eviocrevoke(int fd) {
static bool warned = false;
assert(fd >= 0);
if (ioctl(fd, EVIOCREVOKE, NULL) < 0) {
if (errno == EINVAL && !warned) {
log_warning_errno(errno, "Kernel does not support evdev-revocation: %m");
warned = true;
}
}
}
static int sd_drmsetmaster(int fd) {
assert(fd >= 0);
if (ioctl(fd, DRM_IOCTL_SET_MASTER, 0) < 0)
return -errno;
return 0;
}
static int sd_drmdropmaster(int fd) {
assert(fd >= 0);
if (ioctl(fd, DRM_IOCTL_DROP_MASTER, 0) < 0)
return -errno;
return 0;
}
static int session_device_open(SessionDevice *sd, bool active) {
int fd, r;
assert(sd);
assert(sd->type != DEVICE_TYPE_UNKNOWN);
assert(sd->node);
/* open device and try to get an udev_device from it */
fd = open(sd->node, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
if (fd < 0)
return -errno;
switch (sd->type) {
case DEVICE_TYPE_DRM:
if (active) {
/* Weird legacy DRM semantics might return an error even though we're master. No way to detect
* that so fail at all times and let caller retry in inactive state. */
r = sd_drmsetmaster(fd);
if (r < 0) {
close_nointr(fd);
return r;
}
} else
/* DRM-Master is granted to the first user who opens a device automatically (ughh,
* racy!). Hence, we just drop DRM-Master in case we were the first. */
(void) sd_drmdropmaster(fd);
break;
case DEVICE_TYPE_EVDEV:
if (!active)
sd_eviocrevoke(fd);
break;
case DEVICE_TYPE_UNKNOWN:
default:
/* fallback for devices wihout synchronizations */
break;
}
return fd;
}
static int session_device_start(SessionDevice *sd) {
int r;
assert(sd);
assert(session_is_active(sd->session));
if (sd->active)
return 0;
switch (sd->type) {
case DEVICE_TYPE_DRM:
if (sd->fd < 0) {
log_error("Failed to re-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
return -EBADF;
}
/* Device is kept open. Simply call drmSetMaster() and hope there is no-one else. In case it fails, we
* keep the device paused. Maybe at some point we have a drmStealMaster(). */
r = sd_drmsetmaster(sd->fd);
if (r < 0)
return r;
break;
case DEVICE_TYPE_EVDEV:
/* Evdev devices are revoked while inactive. Reopen it and we are fine. */
r = session_device_open(sd, true);
if (r < 0)
return r;
/* For evdev devices, the file descriptor might be left uninitialized. This might happen while resuming
* into a session and logind has been restarted right before. */
safe_close(sd->fd);
sd->fd = r;
break;
case DEVICE_TYPE_UNKNOWN:
default:
/* fallback for devices without synchronizations */
break;
}
sd->active = true;
return 0;
}
static void session_device_stop(SessionDevice *sd) {
assert(sd);
if (!sd->active)
return;
switch (sd->type) {
case DEVICE_TYPE_DRM:
if (sd->fd < 0) {
log_error("Failed to de-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)");
return;
}
/* On DRM devices we simply drop DRM-Master but keep it open.
* This allows the user to keep resources allocated. The
* CAP_SYS_ADMIN restriction to DRM-Master prevents users from
* circumventing this. */
sd_drmdropmaster(sd->fd);
break;
case DEVICE_TYPE_EVDEV:
/* Revoke access on evdev file-descriptors during deactivation.
* This will basically prevent any operations on the fd and
* cannot be undone. Good side is: it needs no CAP_SYS_ADMIN
* protection this way. */
sd_eviocrevoke(sd->fd);
break;
case DEVICE_TYPE_UNKNOWN:
default:
/* fallback for devices without synchronization */
break;
}
sd->active = false;
}
static DeviceType detect_device_type(struct udev_device *dev) {
const char *sysname, *subsystem;
DeviceType type;
sysname = udev_device_get_sysname(dev);
subsystem = udev_device_get_subsystem(dev);
type = DEVICE_TYPE_UNKNOWN;
if (streq_ptr(subsystem, "drm")) {
if (startswith(sysname, "card"))
type = DEVICE_TYPE_DRM;
} else if (streq_ptr(subsystem, "input")) {
if (startswith(sysname, "event"))
type = DEVICE_TYPE_EVDEV;
}
return type;
}
static int session_device_verify(SessionDevice *sd) {
struct udev_device *dev, *p = NULL;
const char *sp, *node;
int r;
dev = udev_device_new_from_devnum(sd->session->manager->udev, 'c', sd->dev);
if (!dev)
return -ENODEV;
sp = udev_device_get_syspath(dev);
node = udev_device_get_devnode(dev);
if (!node) {
r = -EINVAL;
goto err_dev;
}
/* detect device type so we can find the correct sysfs parent */
sd->type = detect_device_type(dev);
if (sd->type == DEVICE_TYPE_UNKNOWN) {
r = -ENODEV;
goto err_dev;
} else if (sd->type == DEVICE_TYPE_EVDEV) {
/* for evdev devices we need the parent node as device */
p = dev;
dev = udev_device_get_parent_with_subsystem_devtype(p, "input", NULL);
if (!dev) {
r = -ENODEV;
goto err_dev;
}
sp = udev_device_get_syspath(dev);
} else if (sd->type != DEVICE_TYPE_DRM) {
/* Prevent opening unsupported devices. Especially devices of
* subsystem "input" must be opened via the evdev node as
* we require EVIOCREVOKE. */
r = -ENODEV;
goto err_dev;
}
/* search for an existing seat device and return it if available */
sd->device = hashmap_get(sd->session->manager->devices, sp);
if (!sd->device) {
/* The caller might have gotten the udev event before we were
* able to process it. Hence, fake the "add" event and let the
* logind-manager handle the new device. */
r = manager_process_seat_device(sd->session->manager, dev);
if (r < 0)
goto err_dev;
/* if it's still not available, then the device is invalid */
sd->device = hashmap_get(sd->session->manager->devices, sp);
if (!sd->device) {
r = -ENODEV;
goto err_dev;
}
}
if (sd->device->seat != sd->session->seat) {
r = -EPERM;
goto err_dev;
}
sd->node = strdup(node);
if (!sd->node) {
r = -ENOMEM;
goto err_dev;
}
r = 0;
err_dev:
udev_device_unref(p ? : dev);
return r;
}
int session_device_new(Session *s, dev_t dev, bool open_device, SessionDevice **out) {
SessionDevice *sd;
int r;
assert(s);
assert(out);
if (!s->seat)
return -EPERM;
sd = new0(SessionDevice, 1);
if (!sd)
return -ENOMEM;
sd->session = s;
sd->dev = dev;
sd->fd = -1;
sd->type = DEVICE_TYPE_UNKNOWN;
r = session_device_verify(sd);
if (r < 0)
goto error;
r = hashmap_put(s->devices, &sd->dev, sd);
if (r < 0)
goto error;
if (open_device) {
/* Open the device for the first time. We need a valid fd to pass back
* to the caller. If the session is not active, this _might_ immediately
* revoke access and thus invalidate the fd. But this is still needed
* to pass a valid fd back. */
sd->active = session_is_active(s);
r = session_device_open(sd, sd->active);
if (r < 0) {
/* EINVAL _may_ mean a master is active; retry inactive */
if (sd->active && r == -EINVAL) {
sd->active = false;
r = session_device_open(sd, false);
}
if (r < 0)
goto error;
}
sd->fd = r;
}
LIST_PREPEND(sd_by_device, sd->device->session_devices, sd);
*out = sd;
return 0;
error:
hashmap_remove(s->devices, &sd->dev);
free(sd->node);
free(sd);
return r;
}
void session_device_free(SessionDevice *sd) {
assert(sd);
/* Make sure to remove the pushed fd. */
if (sd->pushed_fd) {
_cleanup_free_ char *m = NULL;
const char *id;
int r;
/* Session ID does not contain separators. */
id = sd->session->id;
assert(*(id + strcspn(id, "-\n")) == '\0');
r = asprintf(&m, "FDSTOREREMOVE=1\n"
"FDNAME=session-%s-device-%u-%u\n",
id, major(sd->dev), minor(sd->dev));
if (r >= 0)
(void) sd_notify(false, m);
}
session_device_stop(sd);
session_device_notify(sd, SESSION_DEVICE_RELEASE);
safe_close(sd->fd);
LIST_REMOVE(sd_by_device, sd->device->session_devices, sd);
hashmap_remove(sd->session->devices, &sd->dev);
free(sd->node);
free(sd);
}
void session_device_complete_pause(SessionDevice *sd) {
SessionDevice *iter;
Iterator i;
if (!sd->active)
return;
session_device_stop(sd);
/* if not all devices are paused, wait for further completion events */
HASHMAP_FOREACH(iter, sd->session->devices, i)
if (iter->active)
return;
/* complete any pending session switch */
seat_complete_switch(sd->session->seat);
}
void session_device_resume_all(Session *s) {
SessionDevice *sd;
Iterator i;
assert(s);
HASHMAP_FOREACH(sd, s->devices, i) {
if (sd->active)
continue;
if (session_device_start(sd) < 0)
continue;
if (session_device_save(sd) < 0)
continue;
session_device_notify(sd, SESSION_DEVICE_RESUME);
}
}
void session_device_pause_all(Session *s) {
SessionDevice *sd;
Iterator i;
assert(s);
HASHMAP_FOREACH(sd, s->devices, i) {
if (!sd->active)
continue;
session_device_stop(sd);
session_device_notify(sd, SESSION_DEVICE_PAUSE);
}
}
unsigned int session_device_try_pause_all(Session *s) {
unsigned num_pending = 0;
SessionDevice *sd;
Iterator i;
assert(s);
HASHMAP_FOREACH(sd, s->devices, i) {
if (!sd->active)
continue;
session_device_notify(sd, SESSION_DEVICE_TRY_PAUSE);
num_pending++;
}
return num_pending;
}
int session_device_save(SessionDevice *sd) {
_cleanup_free_ char *m = NULL;
const char *id;
int r;
assert(sd);
/* Store device fd in PID1. It will send it back to us on restart so revocation will continue to work. To make
* things simple, send fds for all type of devices even if they don't support the revocation mechanism so we
* don't have to handle them differently later.
*
* Note: for device supporting revocation, PID1 will drop a stored fd automatically if the corresponding device
* is revoked. */
if (sd->pushed_fd)
return 0;
/* Session ID does not contain separators. */
id = sd->session->id;
assert(*(id + strcspn(id, "-\n")) == '\0');
r = asprintf(&m, "FDSTORE=1\n"
"FDNAME=session-%s-device-%u-%u\n",
id, major(sd->dev), minor(sd->dev));
if (r < 0)
return r;
r = sd_pid_notify_with_fds(0, false, m, &sd->fd, 1);
if (r < 0)
return r;
sd->pushed_fd = true;
return 1;
}
void session_device_attach_fd(SessionDevice *sd, int fd, bool active) {
assert(fd >= 0);
assert(sd);
assert(sd->fd < 0);
assert(!sd->active);
sd->fd = fd;
sd->pushed_fd = true;
sd->active = active;
}
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