diff options
Diffstat (limited to 'src/login/logind-session-device.c')
| -rw-r--r-- | src/login/logind-session-device.c | 518 |
1 files changed, 518 insertions, 0 deletions
diff --git a/src/login/logind-session-device.c b/src/login/logind-session-device.c new file mode 100644 index 0000000..f2adb96 --- /dev/null +++ b/src/login/logind-session-device.c @@ -0,0 +1,518 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <fcntl.h> +#include <string.h> +#include <sys/ioctl.h> +#include <sys/types.h> + +#include "sd-device.h" +#include "sd-daemon.h" + +#include "alloc-util.h" +#include "bus-util.h" +#include "fd-util.h" +#include "logind-session-dbus.h" +#include "logind-session-device.h" +#include "missing_drm.h" +#include "missing_input.h" +#include "parse-util.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 without 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) + return log_error_errno(SYNTHETIC_ERRNO(EBADF), + "Failed to re-activate DRM fd, as the fd was lost (maybe logind restart went wrong?)"); + + /* 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. */ + CLOSE_AND_REPLACE(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(sd_device *dev) { + const char *sysname, *subsystem; + DeviceType type = DEVICE_TYPE_UNKNOWN; + + if (sd_device_get_sysname(dev, &sysname) < 0 || + sd_device_get_subsystem(dev, &subsystem) < 0) + return type; + + if (streq(subsystem, "drm")) { + if (startswith(sysname, "card")) + type = DEVICE_TYPE_DRM; + } else if (streq(subsystem, "input")) { + if (startswith(sysname, "event")) + type = DEVICE_TYPE_EVDEV; + } + + return type; +} + +static int session_device_verify(SessionDevice *sd) { + _cleanup_(sd_device_unrefp) sd_device *p = NULL; + const char *sp, *node; + sd_device *dev; + int r; + + r = sd_device_new_from_devnum(&p, 'c', sd->dev); + if (r < 0) + return r; + + dev = p; + + if (sd_device_get_syspath(dev, &sp) < 0 || + sd_device_get_devname(dev, &node) < 0) + return -EINVAL; + + /* detect device type so we can find the correct sysfs parent */ + sd->type = detect_device_type(dev); + if (sd->type == DEVICE_TYPE_UNKNOWN) + return -ENODEV; + + else if (sd->type == DEVICE_TYPE_EVDEV) { + /* for evdev devices we need the parent node as device */ + if (sd_device_get_parent_with_subsystem_devtype(p, "input", NULL, &dev) < 0) + return -ENODEV; + if (sd_device_get_syspath(dev, &sp) < 0) + return -ENODEV; + + } 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. */ + return -ENODEV; + + /* 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) + return r; + + /* if it's still not available, then the device is invalid */ + sd->device = hashmap_get(sd->session->manager->devices, sp); + if (!sd->device) + return -ENODEV; + } + + if (sd->device->seat != sd->session->seat) + return -EPERM; + + sd->node = strdup(node); + if (!sd->node) + return -ENOMEM; + + return 0; +} + +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) + (void) sd_notifyf(false, + "FDSTOREREMOVE=1\n" + "FDNAME=session-%s-device-%u-%u", + sd->session->id, major(sd->dev), minor(sd->dev)); + + 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; + + 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) + if (iter->active) + return; + + /* complete any pending session switch */ + seat_complete_switch(sd->session->seat); +} + +void session_device_resume_all(Session *s) { + SessionDevice *sd; + + assert(s); + + HASHMAP_FOREACH(sd, s->devices) { + 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; + + assert(s); + + HASHMAP_FOREACH(sd, s->devices) { + if (!sd->active) + continue; + + session_device_stop(sd); + session_device_notify(sd, SESSION_DEVICE_PAUSE); + } +} + +unsigned session_device_try_pause_all(Session *s) { + unsigned num_pending = 0; + SessionDevice *sd; + + assert(s); + + HASHMAP_FOREACH(sd, s->devices) { + 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; +} |