/*
 * Copyright (c) 2017 Richard Palethorpe <rpalethorpe@suse.com>
 * Copyright (c) 2012, Kees Cook <keescook@chromium.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
/*
 * Check that memory after the string terminator in all the utsname fields has
 * been zeroed. cve-2012-0957 leaked kernel memory through the release field
 * when the UNAME26 personality was set.
 *
 * Thanks to Kees Cook for the original proof of concept:
 * http://www.securityfocus.com/bid/55855/info
 */

#include <string.h>
#include <sys/utsname.h>
#include <sys/personality.h>
#include "tst_test.h"

#define UNAME26 0x0020000

static int check_field(char *bytes, size_t length, char *field)
{
	size_t i = strlen(bytes) + 1;

	for (; i < length; i++) {
		if (bytes[i]) {
			tst_res(TFAIL, "Bytes leaked in %s!", field);
			return 1;
		}
	}
	return 0;
}


static void try_leak_bytes(void)
{
	struct utsname buf;

	if (uname(&buf))
		tst_brk(TBROK | TERRNO, "Call to uname failed");

#define CHECK_FIELD(field_name) \
	(check_field(buf.field_name, ARRAY_SIZE(buf.field_name), #field_name))

	if (!(CHECK_FIELD(release) |
	    CHECK_FIELD(sysname) |
	    CHECK_FIELD(nodename) |
	    CHECK_FIELD(version) |
	    CHECK_FIELD(machine) |
#ifdef HAVE_STRUCT_UTSNAME_DOMAINNAME
	    CHECK_FIELD(domainname) |
#endif
		    0)) {
		tst_res(TPASS, "All fields zeroed after string terminator");
	}
#undef CHECK_FIELD
}

static void run(unsigned int test_nr)
{
	if (!test_nr) {
		tst_res(TINFO, "Calling uname with default personality");
		try_leak_bytes();
	} else {
		if (personality(PER_LINUX | UNAME26) < 0)
			tst_brk(TCONF | TERRNO,
				"Could not change personality to UNAME26");
		tst_res(TINFO, "Calling uname with UNAME26 personality");
		try_leak_bytes();
	}
}

static struct tst_test test = {
	.test = run,
	.tcnt = 2,
};
