audit: allow audit matching on inode gid

Much like the ability to filter audit on the uid of an inode collected, we
should be able to filter on the gid of the inode.

Signed-off-by: Eric Paris <eparis@redhat.com>

kernel/auditsc.c

@@ -598,6 +598,18 @@ static int audit_filter_rules(struct task_struct *tsk,
 				}
 			}
 			break;
+		case AUDIT_OBJ_GID:
+			if (name) {
+				result = audit_comparator(name->gid, f->op, f->val);
+			} else if (ctx) {
+				list_for_each_entry(n, &ctx->names_list, list) {
+					if (audit_comparator(n->gid, f->op, f->val)) {
+						++result;
+						break;
+					}
+				}
+			}
+			break;
 		case AUDIT_WATCH:
 			if (name)
 				result = audit_watch_compare(rule->watch, name->ino, name->dev);