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/* $NetBSD: t_mprotect.c,v 1.3 2011/07/20 22:53:44 jym Exp $ */
/*-
* Copyright (c) 2011 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jukka Ruohonen.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: t_mprotect.c,v 1.3 2011/07/20 22:53:44 jym Exp $");
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/sysctl.h>
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <atf-c.h>
#include "../common/exec_prot.h"
static long page = 0;
static int pax_global = -1;
static int pax_enabled = -1;
static char path[] = "mmap";
static void sighandler(int);
static bool paxinit(void);
static bool paxset(int, int);
static void
sighandler(int signo)
{
_exit(signo);
}
static bool
paxinit(void)
{
size_t len = sizeof(int);
int rv;
rv = sysctlbyname("security.pax.mprotect.global",
&pax_global, &len, NULL, 0);
if (rv != 0)
return false;
rv = sysctlbyname("security.pax.mprotect.enabled",
&pax_enabled, &len, NULL, 0);
if (rv != 0)
return false;
return paxset(1, 1);
}
static bool
paxset(int global, int enabled)
{
size_t len = sizeof(int);
int rv;
rv = sysctlbyname("security.pax.mprotect.global",
NULL, NULL, &global, len);
if (rv != 0)
return false;
rv = sysctlbyname("security.pax.mprotect.enabled",
NULL, NULL, &enabled, len);
if (rv != 0)
return false;
return true;
}
ATF_TC_WITH_CLEANUP(mprotect_access);
ATF_TC_HEAD(mprotect_access, tc)
{
atf_tc_set_md_var(tc, "descr", "Test for EACCES from mprotect(2)");
}
ATF_TC_BODY(mprotect_access, tc)
{
int prot[2] = { PROT_NONE, PROT_READ };
void *map;
size_t i;
int fd;
fd = open(path, O_RDONLY | O_CREAT);
ATF_REQUIRE(fd >= 0);
/*
* The call should fail with EACCES if we try to mark
* a PROT_NONE or PROT_READ file/section as PROT_WRITE.
*/
for (i = 0; i < __arraycount(prot); i++) {
map = mmap(NULL, page, prot[i], MAP_SHARED, fd, 0);
if (map == MAP_FAILED)
continue;
errno = 0;
ATF_REQUIRE(mprotect(map, page, PROT_WRITE) != 0);
ATF_REQUIRE(errno == EACCES);
ATF_REQUIRE(munmap(map, page) == 0);
}
ATF_REQUIRE(close(fd) == 0);
}
ATF_TC_CLEANUP(mprotect_access, tc)
{
(void)unlink(path);
}
ATF_TC(mprotect_err);
ATF_TC_HEAD(mprotect_err, tc)
{
atf_tc_set_md_var(tc, "descr", "Test error conditions of mprotect(2)");
}
ATF_TC_BODY(mprotect_err, tc)
{
errno = 0;
ATF_REQUIRE(mprotect((char *)-1, 1, PROT_READ) != 0);
ATF_REQUIRE(errno == EINVAL);
}
ATF_TC(mprotect_exec);
ATF_TC_HEAD(mprotect_exec, tc)
{
atf_tc_set_md_var(tc, "descr",
"Test mprotect(2) executable space protections");
}
/*
* Trivial function -- should fit into a page
*/
ATF_TC_BODY(mprotect_exec, tc)
{
pid_t pid;
void *map;
int sta, xp_support;
xp_support = exec_prot_support();
switch (xp_support) {
case NOTIMPL:
atf_tc_skip(
"Execute protection callback check not implemented");
break;
case NO_XP:
atf_tc_skip(
"Host does not support executable space protection");
break;
case PARTIAL_XP: case PERPAGE_XP: default:
break;
}
/*
* Map a page read/write and copy a trivial assembly function inside.
* We will then change the mapping rights:
* - first by setting the execution right, and check that we can
* call the code found in the allocated page.
* - second by removing the execution right. This should generate
* a SIGSEGV on architectures that can enforce --x permissions.
*/
map = mmap(NULL, page, PROT_WRITE|PROT_READ, MAP_ANON, -1, 0);
ATF_REQUIRE(map != MAP_FAILED);
memcpy(map, (void *)return_one,
(uintptr_t)return_one_end - (uintptr_t)return_one);
/* give r-x rights then call code in page */
ATF_REQUIRE(mprotect(map, page, PROT_EXEC|PROT_READ) == 0);
ATF_REQUIRE(((int (*)(void))map)() == 1);
/* remove --x right */
ATF_REQUIRE(mprotect(map, page, PROT_READ) == 0);
pid = fork();
ATF_REQUIRE(pid >= 0);
if (pid == 0) {
ATF_REQUIRE(signal(SIGSEGV, sighandler) != SIG_ERR);
ATF_CHECK(((int (*)(void))map)() == 1);
_exit(0);
}
(void)wait(&sta);
ATF_REQUIRE(munmap(map, page) == 0);
ATF_REQUIRE(WIFEXITED(sta) != 0);
switch (xp_support) {
case PARTIAL_XP:
/* Partial protection might fail; skip the test when it does */
if (WEXITSTATUS(sta) != SIGSEGV) {
atf_tc_skip("Host only supports "
"partial executable space protection");
}
break;
case PERPAGE_XP: default:
/* Per-page --x protection should not fail */
ATF_REQUIRE(WEXITSTATUS(sta) == SIGSEGV);
break;
}
}
ATF_TC(mprotect_pax);
ATF_TC_HEAD(mprotect_pax, tc)
{
atf_tc_set_md_var(tc, "descr", "PaX restrictions and mprotect(2)");
atf_tc_set_md_var(tc, "require.user", "root");
}
ATF_TC_BODY(mprotect_pax, tc)
{
const int prot[4] = { PROT_NONE, PROT_READ, PROT_WRITE };
const char *str = NULL;
void *map;
size_t i;
int rv;
if (paxinit() != true)
return;
/*
* As noted in the original PaX documentation [1],
* the following restrictions should apply:
*
* (1) creating executable anonymous mappings
*
* (2) creating executable/writable file mappings
*
* (3) making a non-executable mapping executable
*
* (4) making an executable/read-only file mapping
* writable except for performing relocations
* on an ET_DYN ELF file (non-PIC shared library)
*
* The following will test only the case (3).
*
* [1] http://pax.grsecurity.net/docs/mprotect.txt
*
* (Sun Apr 3 11:06:53 EEST 2011.)
*/
for (i = 0; i < __arraycount(prot); i++) {
map = mmap(NULL, page, prot[i], MAP_ANON, -1, 0);
if (map == MAP_FAILED)
continue;
rv = mprotect(map, 1, prot[i] | PROT_EXEC);
(void)munmap(map, page);
if (rv == 0) {
str = "non-executable mapping made executable";
goto out;
}
}
out:
if (pax_global != -1 && pax_enabled != -1)
(void)paxset(pax_global, pax_enabled);
if (str != NULL)
atf_tc_fail("%s", str);
}
ATF_TC(mprotect_write);
ATF_TC_HEAD(mprotect_write, tc)
{
atf_tc_set_md_var(tc, "descr", "Test mprotect(2) write protections");
}
ATF_TC_BODY(mprotect_write, tc)
{
pid_t pid;
void *map;
int sta;
/*
* Map a page read/write, change the protection
* to read-only with mprotect(2), and try to write
* to the page. This should generate a SIGSEGV.
*/
map = mmap(NULL, page, PROT_WRITE|PROT_READ, MAP_ANON, -1, 0);
ATF_REQUIRE(map != MAP_FAILED);
ATF_REQUIRE(strlcpy(map, "XXX", 3) == 3);
ATF_REQUIRE(mprotect(map, page, PROT_READ) == 0);
pid = fork();
ATF_REQUIRE(pid >= 0);
if (pid == 0) {
ATF_REQUIRE(signal(SIGSEGV, sighandler) != SIG_ERR);
ATF_REQUIRE(strlcpy(map, "XXX", 3) == 0);
}
(void)wait(&sta);
ATF_REQUIRE(WIFEXITED(sta) != 0);
ATF_REQUIRE(WEXITSTATUS(sta) == SIGSEGV);
ATF_REQUIRE(munmap(map, page) == 0);
}
ATF_TP_ADD_TCS(tp)
{
page = sysconf(_SC_PAGESIZE);
ATF_REQUIRE(page >= 0);
ATF_TP_ADD_TC(tp, mprotect_access);
ATF_TP_ADD_TC(tp, mprotect_err);
ATF_TP_ADD_TC(tp, mprotect_exec);
ATF_TP_ADD_TC(tp, mprotect_pax);
ATF_TP_ADD_TC(tp, mprotect_write);
return atf_no_error();
}
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