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Systemd/src/login/logind-seat-dbus.c
Lennart Poettering 3b92c086a8 logind: make "self" and "auto" magic strings when operating on seats + sessions 
Most of the operations one can do on sessions so far accepted an empty
session name as a shortcut for the caller's session. This is quite
useful traditionally, but much less useful than it used to be, since
most user code now (rightfully) runs in --user context, not in a
session.

With this change we tweak the logic a bit: we introduce the two special
session and seat names "self" and "auto". The former refers to the
session/seat the client is in, and is hence mostly equivalent to te
empty string "" as before. However, the latter refers to the
session/seat the client is in if that exists, with a fallback of the
user's display session if not. Clients can hence reference "auto"
instead of the empty string if they really don't want to think much
about sessions.

Why "self" btw? Previously, we'd already expose a special dbus object
with the path /org/freedesktop/login1/session/self (and similar for the
seat), matching what the empty string did for bus calls that took a
session name. With this scheme we reuse this identifier and introduce
"auto" in a similar way.

Of course this means real-life seats and sessions can never be named
"self" or "auto", but they aren't anyway: valid seat names have to start
with "seat" anyway, and sessions are generated server-side as either a
numeric value or "c" suffixed with a counter ID.

Fixes: #12399
2019-05-24 15:05:27 +02:00

412 lines
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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <errno.h>
#include <string.h>
#include "alloc-util.h"
#include "bus-common-errors.h"
#include "bus-label.h"
#include "bus-util.h"
#include "logind-seat.h"
#include "logind.h"
#include "missing_capability.h"
#include "strv.h"
#include "user-util.h"
#include "util.h"
static BUS_DEFINE_PROPERTY_GET(property_get_can_multi_session, "b", Seat, seat_can_multi_session);
static BUS_DEFINE_PROPERTY_GET(property_get_can_tty, "b", Seat, seat_can_tty);
static BUS_DEFINE_PROPERTY_GET(property_get_can_graphical, "b", Seat, seat_can_graphical);
static int property_get_active_session(
sd_bus *bus,
const char *path,
const char *interface,
const char *property,
sd_bus_message *reply,
void *userdata,
sd_bus_error *error) {
_cleanup_free_ char *p = NULL;
Seat *s = userdata;
assert(bus);
assert(reply);
assert(s);
p = s->active ? session_bus_path(s->active) : strdup("/");
if (!p)
return -ENOMEM;
return sd_bus_message_append(reply, "(so)", s->active ? s->active->id : "", p);
}
static int property_get_sessions(
sd_bus *bus,
const char *path,
const char *interface,
const char *property,
sd_bus_message *reply,
void *userdata,
sd_bus_error *error) {
Seat *s = userdata;
Session *session;
int r;
assert(bus);
assert(reply);
assert(s);
r = sd_bus_message_open_container(reply, 'a', "(so)");
if (r < 0)
return r;
LIST_FOREACH(sessions_by_seat, session, s->sessions) {
_cleanup_free_ char *p = NULL;
p = session_bus_path(session);
if (!p)
return -ENOMEM;
r = sd_bus_message_append(reply, "(so)", session->id, p);
if (r < 0)
return r;
}
r = sd_bus_message_close_container(reply);
if (r < 0)
return r;
return 1;
}
static int property_get_idle_hint(
sd_bus *bus,
const char *path,
const char *interface,
const char *property,
sd_bus_message *reply,
void *userdata,
sd_bus_error *error) {
Seat *s = userdata;
assert(bus);
assert(reply);
assert(s);
return sd_bus_message_append(reply, "b", seat_get_idle_hint(s, NULL) > 0);
}
static int property_get_idle_since_hint(
sd_bus *bus,
const char *path,
const char *interface,
const char *property,
sd_bus_message *reply,
void *userdata,
sd_bus_error *error) {
Seat *s = userdata;
dual_timestamp t;
uint64_t u;
int r;
assert(bus);
assert(reply);
assert(s);
r = seat_get_idle_hint(s, &t);
if (r < 0)
return r;
u = streq(property, "IdleSinceHint") ? t.realtime : t.monotonic;
return sd_bus_message_append(reply, "t", u);
}
int bus_seat_method_terminate(sd_bus_message *message, void *userdata, sd_bus_error *error) {
Seat *s = userdata;
int r;
assert(message);
assert(s);
r = bus_verify_polkit_async(
message,
CAP_KILL,
"org.freedesktop.login1.manage",
NULL,
false,
UID_INVALID,
&s->manager->polkit_registry,
error);
if (r < 0)
return r;
if (r == 0)
return 1; /* Will call us back */
r = seat_stop_sessions(s, true);
if (r < 0)
return r;
return sd_bus_reply_method_return(message, NULL);
}
static int method_activate_session(sd_bus_message *message, void *userdata, sd_bus_error *error) {
Seat *s = userdata;
const char *name;
Session *session;
int r;
assert(message);
assert(s);
r = sd_bus_message_read(message, "s", &name);
if (r < 0)
return r;
session = hashmap_get(s->manager->sessions, name);
if (!session)
return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_SESSION, "No session '%s' known", name);
if (session->seat != s)
return sd_bus_error_setf(error, BUS_ERROR_SESSION_NOT_ON_SEAT, "Session %s not on seat %s", name, s->id);
r = session_activate(session);
if (r < 0)
return r;
return sd_bus_reply_method_return(message, NULL);
}
static int method_switch_to(sd_bus_message *message, void *userdata, sd_bus_error *error) {
Seat *s = userdata;
unsigned to;
int r;
assert(message);
assert(s);
r = sd_bus_message_read(message, "u", &to);
if (r < 0)
return r;
if (to <= 0)
return -EINVAL;
r = seat_switch_to(s, to);
if (r < 0)
return r;
return sd_bus_reply_method_return(message, NULL);
}
static int method_switch_to_next(sd_bus_message *message, void *userdata, sd_bus_error *error) {
Seat *s = userdata;
int r;
assert(message);
assert(s);
r = seat_switch_to_next(s);
if (r < 0)
return r;
return sd_bus_reply_method_return(message, NULL);
}
static int method_switch_to_previous(sd_bus_message *message, void *userdata, sd_bus_error *error) {
Seat *s = userdata;
int r;
assert(message);
assert(s);
r = seat_switch_to_previous(s);
if (r < 0)
return r;
return sd_bus_reply_method_return(message, NULL);
}
const sd_bus_vtable seat_vtable[] = {
SD_BUS_VTABLE_START(0),
SD_BUS_PROPERTY("Id", "s", NULL, offsetof(Seat, id), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("ActiveSession", "(so)", property_get_active_session, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
SD_BUS_PROPERTY("CanMultiSession", "b", property_get_can_multi_session, 0, SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("CanTTY", "b", property_get_can_tty, 0, SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("CanGraphical", "b", property_get_can_graphical, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
SD_BUS_PROPERTY("Sessions", "a(so)", property_get_sessions, 0, 0),
SD_BUS_PROPERTY("IdleHint", "b", property_get_idle_hint, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
SD_BUS_PROPERTY("IdleSinceHint", "t", property_get_idle_since_hint, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
SD_BUS_PROPERTY("IdleSinceHintMonotonic", "t", property_get_idle_since_hint, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
SD_BUS_METHOD("Terminate", NULL, NULL, bus_seat_method_terminate, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("ActivateSession", "s", NULL, method_activate_session, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("SwitchTo", "u", NULL, method_switch_to, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("SwitchToNext", NULL, NULL, method_switch_to_next, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("SwitchToPrevious", NULL, NULL, method_switch_to_previous, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_VTABLE_END
};
int seat_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error) {
_cleanup_free_ char *e = NULL;
sd_bus_message *message;
Manager *m = userdata;
const char *p;
Seat *seat;
int r;
assert(bus);
assert(path);
assert(interface);
assert(found);
assert(m);
p = startswith(path, "/org/freedesktop/login1/seat/");
if (!p)
return 0;
e = bus_label_unescape(p);
if (!e)
return -ENOMEM;
message = sd_bus_get_current_message(bus);
if (!message)
return 0;
r = manager_get_seat_from_creds(m, message, e, error, &seat);
if (r == -ENXIO) {
sd_bus_error_free(error);
return 0;
}
if (r < 0)
return r;
*found = seat;
return 1;
}
char *seat_bus_path(Seat *s) {
_cleanup_free_ char *t = NULL;
assert(s);
t = bus_label_escape(s->id);
if (!t)
return NULL;
return strappend("/org/freedesktop/login1/seat/", t);
}
int seat_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***nodes, sd_bus_error *error) {
_cleanup_strv_free_ char **l = NULL;
sd_bus_message *message;
Manager *m = userdata;
Seat *seat;
Iterator i;
int r;
assert(bus);
assert(path);
assert(nodes);
HASHMAP_FOREACH(seat, m->seats, i) {
char *p;
p = seat_bus_path(seat);
if (!p)
return -ENOMEM;
r = strv_consume(&l, p);
if (r < 0)
return r;
}
message = sd_bus_get_current_message(bus);
if (message) {
_cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_SESSION|SD_BUS_CREDS_OWNER_UID|SD_BUS_CREDS_AUGMENT, &creds);
if (r >= 0) {
bool may_auto = false;
const char *name;
r = sd_bus_creds_get_session(creds, &name);
if (r >= 0) {
Session *session;
session = hashmap_get(m->sessions, name);
if (session && session->seat) {
r = strv_extend(&l, "/org/freedesktop/login1/seat/self");
if (r < 0)
return r;
may_auto = true;
}
}
if (!may_auto) {
uid_t uid;
r = sd_bus_creds_get_owner_uid(creds, &uid);
if (r >= 0) {
User *user;
user = hashmap_get(m->users, UID_TO_PTR(uid));
may_auto = user && user->display && user->display->seat;
}
}
if (may_auto) {
r = strv_extend(&l, "/org/freedesktop/login1/seat/auto");
if (r < 0)
return r;
}
}
}
*nodes = TAKE_PTR(l);
return 1;
}
int seat_send_signal(Seat *s, bool new_seat) {
_cleanup_free_ char *p = NULL;
assert(s);
p = seat_bus_path(s);
if (!p)
return -ENOMEM;
return sd_bus_emit_signal(
s->manager->bus,
"/org/freedesktop/login1",
"org.freedesktop.login1.Manager",
new_seat ? "SeatNew" : "SeatRemoved",
"so", s->id, p);
}
int seat_send_changed(Seat *s, const char *properties, ...) {
_cleanup_free_ char *p = NULL;
char **l;
assert(s);
if (!s->started)
return 0;
p = seat_bus_path(s);
if (!p)
return -ENOMEM;
l = strv_from_stdarg_alloca(properties);
return sd_bus_emit_properties_changed_strv(s->manager->bus, p, "org.freedesktop.login1.Seat", l);
}
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