From 4887f9ab1f8b585fad235d1bbd5407a5fda84402 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 22 Mar 2012 02:06:40 +0100
Subject: [PATCH] logind: close FIFO before ending sessions cleanly

For clean session endings ask logind explicitly to get rid of the FIFO
before closing it so that the FIFO logic doesn't result in su/sudo to be
terminated immediately.
(cherry picked from commit 75c8e3cffd7da8eede614cf61384957af2c82a29)
---
 src/login/logind-dbus.c |   30 ++++++++++++++++++++
 src/login/pam-module.c  |   71 +++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 98 insertions(+), 3 deletions(-)

diff --git a/src/login/logind-dbus.c b/src/login/logind-dbus.c
index d8f4d89..ea6b89f 100644
--- a/src/login/logind-dbus.c
+++ b/src/login/logind-dbus.c
@@ -80,6 +80,9 @@
         "   <arg name=\"seat\" type=\"s\" direction=\"out\"/>\n"        \
         "   <arg name=\"vtnr\" type=\"u\" direction=\"out\"/>\n"        \
         "  </method>\n"                                                 \
+        "  <method name=\"ReleaseSession\">\n"                          \
+        "   <arg name=\"id\" type=\"s\" direction=\"in\"/>\n"           \
+        "  </method>\n"                                                 \
         "  <method name=\"ActivateSession\">\n"                         \
         "   <arg name=\"id\" type=\"s\" direction=\"in\"/>\n"           \
         "  </method>\n"                                                 \
@@ -1075,6 +1078,33 @@ static DBusHandlerResult manager_message_handler(
                 if (r < 0)
                         return bus_send_error_reply(connection, message, &error, r);
 
+        } else if (dbus_message_is_method_call(message, "org.freedesktop.login1.Manager", "ReleaseSession")) {
+                const char *name;
+                Session *session;
+
+                if (!dbus_message_get_args(
+                                    message,
+                                    &error,
+                                    DBUS_TYPE_STRING, &name,
+                                    DBUS_TYPE_INVALID))
+                        return bus_send_error_reply(connection, message, &error, -EINVAL);
+
+                session = hashmap_get(m->sessions, name);
+                if (!session)
+                        return bus_send_error_reply(connection, message, &error, -ENOENT);
+
+                /* We use the FIFO to detect stray sessions where the
+                process invoking PAM dies abnormally. We need to make
+                sure that that process is not killed if at the clean
+                end of the session it closes the FIFO. Hence, with
+                this call explicitly turn off the FIFO logic, so that
+                the PAM code can finish clean up on its own */
+                session_remove_fifo(session);
+
+                reply = dbus_message_new_method_return(message);
+                if (!reply)
+                        goto oom;
+
         } else if (dbus_message_is_method_call(message, "org.freedesktop.login1.Manager", "ActivateSession")) {
                 const char *name;
                 Session *session;
diff --git a/src/login/pam-module.c b/src/login/pam-module.c
index 8544413..4106d2b 100644
--- a/src/login/pam-module.c
+++ b/src/login/pam-module.c
@@ -414,7 +414,6 @@ _public_ PAM_EXTERN int pam_sm_open_session(
                         "/org/freedesktop/login1",
                         "org.freedesktop.login1.Manager",
                         "CreateSession");
-
         if (!m) {
                 pam_syslog(handle, LOG_ERR, "Could not allocate create session message.");
                 r = PAM_BUF_ERR;
@@ -620,11 +619,77 @@ _public_ PAM_EXTERN int pam_sm_close_session(
                 int argc, const char **argv) {
 
         const void *p = NULL;
+        const char *id;
+        DBusConnection *bus = NULL;
+        DBusMessage *m = NULL, *reply = NULL;
+        DBusError error;
+        int r;
 
-        pam_get_data(handle, "systemd.session-fd", &p);
+        assert(handle);
+
+        dbus_error_init(&error);
+
+        id = pam_getenv(handle, "XDG_SESSION_ID");
+        if (id) {
+
+                /* Before we go and close the FIFO we need to tell
+                 * logind that this is a clean session shutdown, so
+                 * that it doesn't just go and slaughter us
+                 * immediately after closing the fd */
+
+                bus = dbus_bus_get_private(DBUS_BUS_SYSTEM, &error);
+                if (!bus) {
+                        pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", bus_error_message(&error));
+                        r = PAM_SESSION_ERR;
+                        goto finish;
+                }
+
+                m = dbus_message_new_method_call(
+                                "org.freedesktop.login1",
+                                "/org/freedesktop/login1",
+                                "org.freedesktop.login1.Manager",
+                                "ReleaseSession");
+                if (!m) {
+                        pam_syslog(handle, LOG_ERR, "Could not allocate release session message.");
+                        r = PAM_BUF_ERR;
+                        goto finish;
+                }
+
+                if (!dbus_message_append_args(m,
+                                              DBUS_TYPE_STRING, &id,
+                                              DBUS_TYPE_INVALID)) {
+                        pam_syslog(handle, LOG_ERR, "Could not attach parameters to message.");
+                        r = PAM_BUF_ERR;
+                        goto finish;
+                }
 
+                reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error);
+                if (!reply) {
+                        pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error));
+                        r = PAM_SESSION_ERR;
+                        goto finish;
+                }
+        }
+
+        r = PAM_SUCCESS;
+
+finish:
+        pam_get_data(handle, "systemd.session-fd", &p);
         if (p)
                 close_nointr(PTR_TO_INT(p) - 1);
 
-        return PAM_SUCCESS;
+        dbus_error_free(&error);
+
+        if (bus) {
+                dbus_connection_close(bus);
+                dbus_connection_unref(bus);
+        }
+
+        if (m)
+                dbus_message_unref(m);
+
+        if (reply)
+                dbus_message_unref(reply);
+
+        return r;
 }