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authorDavid Herrmann <dh.herrmann@gmail.com>2015-09-29 11:36:18 +0200
committerDavid Herrmann <dh.herrmann@gmail.com>2015-11-16 15:34:41 +0100
commita832ab6f9953d070ee8f5cf2c7869425760b2645 (patch)
tree32ac31723b32cbf713a8430b3140ce9ea0942f8b
parent090d92bd6f66afd7c6bf18ef07315058ce826f01 (diff)
login: fix re-use of users
If the last reference to a user is released, we queue stop-jobs for the user-service and slice. Only once those are finished, we drop the user-object. However, if a new session is opened before the user object is fully dropped, we currently incorrectly re-use the object. This has the effect, that we get stale sessions without a valid "systemd --user" instance. Fix this by properly allowing user_start() to be called, even if user->stopping is true.
-rw-r--r--src/login/logind-user.c43
1 files changed, 30 insertions, 13 deletions
diff --git a/src/login/logind-user.c b/src/login/logind-user.c
index b9d9d537e2..778f19b50d 100644
--- a/src/login/logind-user.c
+++ b/src/login/logind-user.c
@@ -452,15 +452,32 @@ int user_start(User *u) {
assert(u);
- if (u->started)
+ if (u->started && !u->stopping)
return 0;
- log_debug("New user %s logged in.", u->name);
-
- /* Make XDG_RUNTIME_DIR */
- r = user_mkdir_runtime_path(u);
- if (r < 0)
- return r;
+ /*
+ * If u->stopping is set, the user is marked for removal and the slice
+ * and service stop-jobs are queued. We have to clear that flag before
+ * queing the start-jobs again. If they succeed, the user object can be
+ * re-used just fine (pid1 takes care of job-ordering and proper
+ * restart), but if they fail, we want to force another user_stop() so
+ * possibly pending units are stopped.
+ * Note that we don't clear u->started, as we have no clue what state
+ * the user is in on failure here. Hence, we pretend the user is
+ * running so it will be properly taken down by GC. However, we clearly
+ * return an error from user_start() in that case, so no further
+ * reference to the user is taken.
+ */
+ u->stopping = false;
+
+ if (!u->started) {
+ log_debug("New user %s logged in.", u->name);
+
+ /* Make XDG_RUNTIME_DIR */
+ r = user_mkdir_runtime_path(u);
+ if (r < 0)
+ return r;
+ }
/* Create cgroup */
r = user_start_slice(u);
@@ -478,16 +495,16 @@ int user_start(User *u) {
if (r < 0)
return r;
- if (!dual_timestamp_is_set(&u->timestamp))
- dual_timestamp_get(&u->timestamp);
-
- u->started = true;
+ if (!u->started) {
+ if (!dual_timestamp_is_set(&u->timestamp))
+ dual_timestamp_get(&u->timestamp);
+ user_send_signal(u, true);
+ u->started = true;
+ }
/* Save new user data */
user_save(u);
- user_send_signal(u, true);
-
return 0;
}