From c81280b16e1831ab0bdd0383486c7e2d1eaf1b5e Mon Sep 17 00:00:00 2001
From: Balint Reczey <balint@balintreczey.hu>
Date: Wed, 4 Dec 2019 18:12:49 +0100
Subject: pam_motd: Export MOTD_SHOWN=pam after showing MOTD

This is a useful indication for update-motd profile.d snippet which can
also try to show MOTD when it is not already shown.

The use-case for that is showing MOTD in shells in containers without
PAM being involved.

* modules/pam_motd/pam_motd.c: Export MOTD_SHOWN=pam after showing MOTD
* modules/pam_motd/pam_motd.8.xml: Mention setting MOTD_SHOWN=pam in the man page
---
 modules/pam_motd/pam_motd.8.xml | 5 +++++
 modules/pam_motd/pam_motd.c     | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/modules/pam_motd/pam_motd.8.xml b/modules/pam_motd/pam_motd.8.xml
index 4e2110c1..d939ad7e 100644
--- a/modules/pam_motd/pam_motd.8.xml
+++ b/modules/pam_motd/pam_motd.8.xml
@@ -77,6 +77,11 @@
     <para>
       <command>ln -s /dev/null /etc/motd.d/my_motd</command>
     </para>
+    <para>
+      The <emphasis remap='B'>MOTD_SHOWN=pam</emphasis> environment variable
+      is set after showing the motd files, even when all of them were silenced
+      using symbolic links.
+    </para>
   </refsect1>
 
   <refsect1 id="pam_motd-options">
diff --git a/modules/pam_motd/pam_motd.c b/modules/pam_motd/pam_motd.c
index dbd718b6..51b0168b 100644
--- a/modules/pam_motd/pam_motd.c
+++ b/modules/pam_motd/pam_motd.c
@@ -396,6 +396,8 @@ int pam_sm_open_session(pam_handle_t *pamh, int flags,
     _pam_drop(motd_dir_path_copy);
     _pam_drop(motd_dir_path_split);
 
+    retval = pam_putenv(pamh, "MOTD_SHOWN=pam");
+
     return retval;
 }
 
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