logind: add a RequiresMountsFor= dependency from the session scope unit to the home directory of the user

This is useful so that during shutdown scope units are always terminated
before the mounts necessary for the home directory.

(Ideally we'd also add a similar dependency from the user@.service
instance to the home directory, but this isn't as easy as that service
is defined statically and not dynamically, and hence not easy to modify
dynamically, in particular when it comes to deps)

src/login/logind-core.c

@@ -134,7 +134,14 @@ int manager_add_session(Manager *m, const char *id, Session **_session) {
         return 0;
 }
 
-int manager_add_user(Manager *m, uid_t uid, gid_t gid, const char *name, User **_user) {
+int manager_add_user(
+                Manager *m,
+                uid_t uid,
+                gid_t gid,
+                const char *name,
+                const char *home,
+                User **_user) {
+
         User *u;
         int r;
 
@@ -143,7 +150,7 @@ int manager_add_user(Manager *m, uid_t uid, gid_t gid, const char *name, User **
 
         u = hashmap_get(m->users, UID_TO_PTR(uid));
         if (!u) {
-                r = user_new(&u, m, uid, gid, name);
+                r = user_new(&u, m, uid, gid, name, home);
                 if (r < 0)
                         return r;
         }
@@ -154,7 +161,12 @@ int manager_add_user(Manager *m, uid_t uid, gid_t gid, const char *name, User **
         return 0;
 }
 
-int manager_add_user_by_name(Manager *m, const char *name, User **_user) {
+int manager_add_user_by_name(
+                Manager *m,
+                const char *name,
+                User **_user) {
+
+        const char *home = NULL;
         uid_t uid;
         gid_t gid;
         int r;
@@ -162,11 +174,11 @@ int manager_add_user_by_name(Manager *m, const char *name, User **_user) {
         assert(m);
         assert(name);
 
-        r = get_user_creds(&name, &uid, &gid, NULL, NULL, 0);
+        r = get_user_creds(&name, &uid, &gid, &home, NULL, 0);
         if (r < 0)
                 return r;
 
-        return manager_add_user(m, uid, gid, name, _user);
+        return manager_add_user(m, uid, gid, name, home, _user);
 }
 
 int manager_add_user_by_uid(Manager *m, uid_t uid, User **_user) {
@@ -179,7 +191,7 @@ int manager_add_user_by_uid(Manager *m, uid_t uid, User **_user) {
         if (!p)
                 return errno > 0 ? -errno : -ENOENT;
 
-        return manager_add_user(m, uid, p->pw_gid, p->pw_name, _user);
+        return manager_add_user(m, uid, p->pw_gid, p->pw_name, p->pw_dir, _user);
 }
 
 int manager_add_inhibitor(Manager *m, const char* id, Inhibitor **_inhibitor) {

src/login/logind-dbus.c

@@ -2935,6 +2935,7 @@ int manager_start_scope(
                 const char *description,
                 char **wants,
                 char **after,
+                const char *requires_mounts_for,
                 sd_bus_message *more_properties,
                 sd_bus_error *error,
                 char **job) {
@@ -2990,6 +2991,12 @@ int manager_start_scope(
                         return r;
         }
 
+        if (!empty_or_root(requires_mounts_for)) {
+                r = sd_bus_message_append(m, "(sv)", "RequiresMountsFor", "as", 1, requires_mounts_for);
+                if (r < 0)
+                        return r;
+        }
+
         /* Make sure that the session shells are terminated with SIGHUP since bash and friends tend to ignore
          * SIGTERM */
         r = sd_bus_message_append(m, "(sv)", "SendSIGHUP", "b", true);

src/login/logind-session.c

@@ -642,6 +642,7 @@ static int session_start_scope(Session *s, sd_bus_message *properties, sd_bus_er
                                 description,
                                 STRV_MAKE(s->user->runtime_dir_service, s->user->service), /* These two have StopWhenUnneeded= set, hence add a dep towards them */
                                 STRV_MAKE("systemd-logind.service", "systemd-user-sessions.service", s->user->runtime_dir_service, s->user->service), /* And order us after some more */
+                                s->user->home,
                                 properties,
                                 error,
                                 &s->scope_job);

src/login/logind-user.c

@@ -30,7 +30,13 @@
 #include "user-util.h"
 #include "util.h"
 
-int user_new(User **ret, Manager *m, uid_t uid, gid_t gid, const char *name) {
+int user_new(User **ret,
+             Manager *m,
+             uid_t uid,
+             gid_t gid,
+             const char *name,
+             const char *home) {
+
         _cleanup_(user_freep) User *u = NULL;
         char lu[DECIMAL_STR_MAX(uid_t) + 1];
         int r;
@@ -54,6 +60,10 @@ int user_new(User **ret, Manager *m, uid_t uid, gid_t gid, const char *name) {
         if (!u->name)
                 return -ENOMEM;
 
+        u->home = strdup(home);
+        if (!u->home)
+                return -ENOMEM;
+
         if (asprintf(&u->state_file, "/run/systemd/users/"UID_FMT, uid) < 0)
                 return -ENOMEM;
 
@@ -124,6 +134,7 @@ User *user_free(User *u) {
         u->runtime_path = mfree(u->runtime_path);
         u->state_file = mfree(u->state_file);
         u->name = mfree(u->name);
+        u->home = mfree(u->home);
 
         return mfree(u);
 }

src/login/logind-user.h

@@ -23,6 +23,7 @@ struct User {
         uid_t uid;
         gid_t gid;
         char *name;
+        char *home;
         char *state_file;
         char *runtime_path;
 
@@ -49,7 +50,7 @@ struct User {
         LIST_FIELDS(User, gc_queue);
 };
 
-int user_new(User **out, Manager *m, uid_t uid, gid_t gid, const char *name);
+int user_new(User **out, Manager *m, uid_t uid, gid_t gid, const char *name, const char *home);
 User *user_free(User *u);
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(User *, user_free);

src/login/logind.h

@@ -134,7 +134,7 @@ int manager_add_device(Manager *m, const char *sysfs, bool master, Device **_dev
 int manager_add_button(Manager *m, const char *name, Button **_button);
 int manager_add_seat(Manager *m, const char *id, Seat **_seat);
 int manager_add_session(Manager *m, const char *id, Session **_session);
-int manager_add_user(Manager *m, uid_t uid, gid_t gid, const char *name, User **_user);
+int manager_add_user(Manager *m, uid_t uid, gid_t gid, const char *name, const char *home, User **_user);
 int manager_add_user_by_name(Manager *m, const char *name, User **_user);
 int manager_add_user_by_uid(Manager *m, uid_t uid, User **_user);
 int manager_add_inhibitor(Manager *m, const char* id, Inhibitor **_inhibitor);
@@ -171,7 +171,7 @@ int bus_manager_shutdown_or_sleep_now_or_later(Manager *m, const char *unit_name
 
 int manager_send_changed(Manager *manager, const char *property, ...) _sentinel_;
 
-int manager_start_scope(Manager *manager, const char *scope, pid_t pid, const char *slice, const char *description, char **wants, char **after, sd_bus_message *more_properties, sd_bus_error *error, char **job);
+int manager_start_scope(Manager *manager, const char *scope, pid_t pid, const char *slice, const char *description, char **wants, char **after, const char *requires_mounts_for, sd_bus_message *more_properties, sd_bus_error *error, char **job);
 int manager_start_unit(Manager *manager, const char *unit, sd_bus_error *error, char **job);
 int manager_stop_unit(Manager *manager, const char *unit, sd_bus_error *error, char **job);
 int manager_abandon_scope(Manager *manager, const char *scope, sd_bus_error *error);