Add a simple regression test for mlock()/munlock() to make sure they

work on a single page as root, and fails on a single page as nobody.
Intended to help diagnose reports regarding insecure memory use with
gnupg.

tools/regression/mlock/Makefile

@@ -0,0 +1,6 @@
+# $FreeBSD$
+
+PROG=	mlock
+NO_MAN=	yes
+
+.include <bsd.prog.mk>

tools/regression/mlock/mlock.c

@@ -0,0 +1,91 @@
+/*-
+ * Copyright (c) 2005 Robert N. M. Watson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/types.h>
+#include <sys/mman.h>
+
+#include <err.h>
+#include <errno.h>
+#include <pwd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define	NOBODY	"nobody"
+
+/*
+ * Simple exercise for the mlock() system call -- confirm that mlock() and
+ * munlock() return success on an anonymously mapped memory page when running
+ * with privilege; confirm that they fail with EPERM when running
+ * unprivileged.
+ */
+int
+main(int argc, char *argv[])
+{
+	struct passwd *pwd;
+	int pagesize;
+	char *page;
+
+	if (geteuid() != 0)
+		errx(-1, "mlock must run as root");
+
+	errno = 0;
+	pwd = getpwnam(NOBODY);
+	if (pwd == NULL && errno == 0)
+		errx(-1, "getpwnam: user \"%s\" not found", NOBODY);
+	if (pwd == NULL)
+		errx(-1, "getpwnam: %s", strerror(errno));
+	if (pwd->pw_uid == 0)
+		errx(-1, "getpwnam: user \"%s\" has uid 0", NOBODY);
+
+	pagesize = getpagesize();
+	page = mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
+	if (page == MAP_FAILED)
+		errx(-1, "mmap: %s", strerror(errno));
+
+	if (mlock(page, pagesize) < 0)
+		errx(-1, "mlock privileged: %s", strerror(errno));
+
+	if (munlock(page, pagesize) < 0)
+		errx(-1, "munlock privileged: %s", strerror(errno));
+
+	if (seteuid(pwd->pw_uid) < 0)
+		errx(-1, "seteuid: %s", strerror(errno));
+
+	if (mlock(page, pagesize) == 0)
+		errx(-1, "mlock unprivileged: succeeded but shouldn't have");
+	if (errno != EPERM)
+		errx(-1, "mlock unprivileged: %s", strerror(errno));
+
+	if (munlock(page, pagesize) == 0)
+		errx(-1, "munlock unprivileged: succeeded but shouldn't have");
+	if (errno != EPERM)
+		errx(-1, "munlock unprivileged: %s", strerror(errno));
+
+	return (0);
+}