From 5f41d1f10fd97e93517b6a762b1bec247f4d1171 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Thu, 6 Feb 2014 18:32:14 +0100 Subject: logind: rework session shutdown logic Simplify the shutdown logic a bit: - Keep the session FIFO around in the PAM module, even after the session shutdown hook has been finished. This allows logind to track precisely when the PAM handler goes away. - In the ReleaseSession() call start a timer, that will stop terminate the session when elapsed. - Never fiddle with the KillMode of scopes to configure whether user processes should be killed or not. Instead, simply leave the scope units around when we terminate a session whose processes should not be killed. - When killing is enabled, stop the session scope on FIFO EOF or after the ReleaseSession() timeout. When killing is disabled, simply tell PID 1 to abandon the scope. Because the scopes stay around and hence all processes are always member of a scope, the system shutdown logic should be more robust, as the scopes can be shutdown as part of the usual shutdown logic. --- src/login/pam-module.c | 28 +++++++++++----------------- 1 file changed, 11 insertions(+), 17 deletions(-) (limited to 'src/login/pam-module.c') diff --git a/src/login/pam-module.c b/src/login/pam-module.c index 3b2966b30c..79a9042ffd 100644 --- a/src/login/pam-module.c +++ b/src/login/pam-module.c @@ -499,7 +499,7 @@ _public_ PAM_EXTERN int pam_sm_close_session( _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; _cleanup_bus_unref_ sd_bus *bus = NULL; - const void *p = NULL, *existing = NULL; + const void *existing = NULL; const char *id; int r; @@ -519,10 +519,8 @@ _public_ PAM_EXTERN int pam_sm_close_session( r = sd_bus_open_system(&bus); if (r < 0) { - pam_syslog(handle, LOG_ERR, - "Failed to connect to system bus: %s", strerror(-r)); - r = PAM_SESSION_ERR; - goto finish; + pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r)); + return PAM_SESSION_ERR; } r = sd_bus_call_method(bus, @@ -535,20 +533,16 @@ _public_ PAM_EXTERN int pam_sm_close_session( "s", id); if (r < 0) { - pam_syslog(handle, LOG_ERR, - "Failed to release session: %s", bus_error_message(&error, r)); - - r = PAM_SESSION_ERR; - goto finish; + pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r)); + return PAM_SESSION_ERR; } } - r = PAM_SUCCESS; + /* Note that we are knowingly leaking the FIFO fd here. This + * way, logind can watch us die. If we closed it here it would + * not have any clue when that is completed. Given that one + * cannot really have multiple PAM sessions open from the same + * process this means we will leak one FD at max. */ -finish: - pam_get_data(handle, "systemd.session-fd", &p); - if (p) - close_nointr(PTR_TO_INT(p) - 1); - - return r; + return PAM_SUCCESS; } -- cgit v1.2.3-54-g00ecf