logind: when a bus call is done on a session, user or seat, optionally determine them from the caller credentials

More specifically, if an operation is requested on a session with an
empty name, the caller's session is used. If an operation is requested
on a seat with an empty name, the seat of the caller's session is used.
Finally, if an operation on the user with UID -1 is requested, the user
of the client's session is used (and not the UID of the client!).

1 files changed, 10 insertions, 17 deletions

diff --git a/src/login/logind-user-dbus.c b/src/login/logind-user-dbus.c
index e811b3736..717740ad0 100644
--- a/src/login/logind-user-dbus.c
+++ b/src/login/logind-user-dbus.c
@@ -235,6 +235,7 @@ const sd_bus_vtable user_vtable[] = {
 
 int user_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error) {
         Manager *m = userdata;
+        uid_t uid;
         User *user;
         int r;
 
@@ -247,39 +248,31 @@ int user_object_find(sd_bus *bus, const char *path, const char *interface, void
         if (streq(path, "/org/freedesktop/login1/user/self")) {
                 _cleanup_bus_creds_unref_ sd_bus_creds *creds = NULL;
                 sd_bus_message *message;
-                pid_t pid;
 
                 message = sd_bus_get_current_message(bus);
                 if (!message)
                         return 0;
 
-                r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_PID, &creds);
+                r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_OWNER_UID|SD_BUS_CREDS_AUGMENT, &creds);
                 if (r < 0)
                         return r;
 
-                r = sd_bus_creds_get_pid(creds, &pid);
-                if (r < 0)
-                        return r;
-
-                r = manager_get_user_by_pid(m, pid, &user);
-                if (r <= 0)
-                        return 0;
+                r = sd_bus_creds_get_owner_uid(creds, &uid);
         } else {
-                unsigned long lu;
                 const char *p;
 
                 p = startswith(path, "/org/freedesktop/login1/user/_");
                 if (!p)
                         return 0;
 
-                r = safe_atolu(p, &lu);
-                if (r < 0)
-                        return 0;
-
-                user = hashmap_get(m->users, ULONG_TO_PTR(lu));
-                if (!user)
-                        return 0;
+                r = parse_uid(p, &uid);
         }
+        if (r < 0)
+                return 0;
+
+        user = hashmap_get(m->users, ULONG_TO_PTR((unsigned long) uid));
+        if (!user)
+                return 0;
 
         *found = user;
         return 1;