Revert "pam_systemd: set $DBUS_SESSION_BUS_ADDRESS unconditionally"

[thirdparty/systemd.git] / src / login / pam_systemd.c

diff --git a/src/login/pam_systemd.c b/src/login/pam_systemd.c
index a33d8f05c50fee73960af5dbed0680a15daa97f7..2fd930ec7d17d4a3c56d5ebb1d68540693f67222 100644 (file)
--- a/src/login/pam_systemd.c
+++ b/src/login/pam_systemd.c
@@ -196,13 +196,30 @@ static int export_legacy_dbus_address(
                 uid_t uid,
                 const char *runtime) {
 
-        _cleanup_free_ char *s = NULL;
+        const char *s;
+        _cleanup_free_ char *t = NULL;
         int r = PAM_BUF_ERR;
 
-        if (asprintf(&s, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
+        /* We need to export $DBUS_SESSION_BUS_ADDRESS because various applications will not connect
+         * correctly to the bus without it. This setting matches what dbus.socket does for the user
+         * session using 'systemctl --user set-environment'. We want to have the same configuration
+         * in processes started from the PAM session.
+         *
+         * The setting of the address is guarded by the access() check because it is also possible to compile
+         * dbus without --enable-user-session, in which case this socket is not used, and
+         * $DBUS_SESSION_BUS_ADDRESS should not be set. An alternative approach would to not do the access()
+         * check here, and let applications try on their own, by using "unix:path=%s/bus;autolaunch:". But we
+         * expect the socket to be present by the time we do this check, so we can just as well check once
+         * here. */
+
+        s = strjoina(runtime, "/bus");
+        if (access(s, F_OK) < 0)
+                return PAM_SUCCESS;
+
+        if (asprintf(&t, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0)
                 goto error;
 
-        r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", s, 0);
+        r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", t, 0);
         if (r != PAM_SUCCESS)
                 goto error;