Update sepgsql to add mandatory access control for TRUNCATE

Use SELinux "db_table: { truncate }" to check if permission is granted to
TRUNCATE. Update example SELinux policy to grant needed permission for
TRUNCATE. Add new regression test to demonstrate a positive and negative
cases. Test will only be run if the loaded SELinux policy has the
"db_table: { truncate }" permission. Makes use of recent commit which added
object TRUNCATE hook. Patch by Yuli Khodorkovskiy with minor
editorialization by me. Not back-patched because the object TRUNCATE hook
was not.

Author: Yuli Khodorkovskiy
Reviewed-by: Joe Conway
Discussion: https://postgr.es/m/CAFL5wJcomybj1Xdw7qWmPJRpGuFukKgNrDb6uVBaCMgYS9dkaA%40mail.gmail.com

1 files changed, 3 insertions, 0 deletions

diff --git a/contrib/sepgsql/selinux.c b/contrib/sepgsql/selinux.c
index b7c489cc336..5e6189a4c31 100644
--- a/contrib/sepgsql/selinux.c
+++ b/contrib/sepgsql/selinux.c
@@ -360,6 +360,9 @@ static struct
 				"lock", SEPG_DB_TABLE__LOCK
 			},
 			{
+				"truncate", SEPG_DB_TABLE__TRUNCATE
+			},
+			{
 				NULL, 0UL
 			},
 		}