[PATCH] gssd: set $HOME to prevent recursion when home dirs are on kerberized NFS mount

[Jeff Layton <jlayton@redhat.com>]

Some krb5 routines will attempt to access files in the user's home
directory. This is problematic for gssd when the user's homedir is
on a kerberized NFS mount as it will end up deadlocked.

Fix this by setting $HOME unconditionally to "/".

Fixes this Fedora bug:

    https://bugzilla.redhat.com/show_bug.cgi?id=1052902

Reported-by: Enrico Scholz <rh-bugzilla@ensc.de>
Reported-by: nmorey <nmorey@kalray.eu>
Tested-by: Michael Young <m.a.young@durham.ac.uk>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 utils/gssd/gssd.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/utils/gssd/gssd.c b/utils/gssd/gssd.c
index fdad153..611ef1a 100644
--- a/utils/gssd/gssd.c
+++ b/utils/gssd/gssd.c
@@ -46,6 +46,7 @@
 
 #include <unistd.h>
 #include <err.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -161,6 +162,18 @@ main(int argc, char *argv[])
 		}
 	}
 
+	/*
+	 * Some krb5 routines try to scrape info out of files in the user's
+	 * home directory. This can easily deadlock when that homedir is on a
+	 * kerberized NFS mount. By setting $HOME unconditionally to "/", we
+	 * prevent this behavior in routines that use $HOME in preference to
+	 * the results of getpw*.
+	 */
+	if (setenv("HOME", "/", 1)) {
+		printerr(1, "Unable to set $HOME: %s\n", strerror(errno));
+		exit(1);
+	}
+
 	i = 0;
 	ccachesearch[i++] = strtok(ccachedir, ":");
 	do {
-- 
1.8.4.2