/* $NetBSD: t_ptrace.c,v 1.18 2017/01/13 21:30:41 christos Exp $ */
/*-
* Copyright (c) 2016 The NetBSD Foundation, Inc.
* 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 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_ptrace.c,v 1.18 2017/01/13 21:30:41 christos Exp $");
#include <sys/param.h>
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <err.h>
#include <errno.h>
#include <unistd.h>
#include <atf-c.h>
#include "h_macros.h"
/*
* A child process cannot call atf functions and expect them to magically
* work like in the parent.
* The printf(3) messaging from a child will not work out of the box as well
* without estabilishing a communication protocol with its parent. To not
* overcomplicate the tests - do not log from a child and use err(3)/errx(3)
* wrapped with FORKEE_ASSERT()/FORKEE_ASSERTX() as that is guaranteed to work.
*/
#define FORKEE_ASSERTX(x) \
do { \
int ret = (x); \
if (!ret) \
errx(EXIT_FAILURE, "%s:%d %s(): Assertion failed for: %s", \
__FILE__, __LINE__, __func__, #x); \
} while (0)
#define FORKEE_ASSERT(x) \
do { \
int ret = (x); \
if (!ret) \
err(EXIT_FAILURE, "%s:%d %s(): Assertion failed for: %s", \
__FILE__, __LINE__, __func__, #x); \
} while (0)
ATF_TC(attach_pid0);
ATF_TC_HEAD(attach_pid0, tc)
{
atf_tc_set_md_var(tc, "descr",
"Assert that a debugger cannot attach to PID 0");
}
ATF_TC_BODY(attach_pid0, tc)
{
errno = 0;
ATF_REQUIRE_ERRNO(EPERM, ptrace(PT_ATTACH, 0, NULL, 0) == -1);
}
ATF_TC(attach_pid1);
ATF_TC_HEAD(attach_pid1, tc)
{
atf_tc_set_md_var(tc, "descr",
"Assert that a debugger cannot attach to PID 1 (as non-root)");
atf_tc_set_md_var(tc, "require.user", "unprivileged");
}
ATF_TC_BODY(attach_pid1, tc)
{
ATF_REQUIRE_ERRNO(EPERM, ptrace(PT_ATTACH, 1, NULL, 0) == -1);
}
ATF_TC(attach_pid1_securelevel);
ATF_TC_HEAD(attach_pid1_securelevel, tc)
{
atf_tc_set_md_var(tc, "descr",
"Assert that a debugger cannot attach to PID 1 with "
"securelevel >= 1 (as root)");
atf_tc_set_md_var(tc, "require.user", "root");
}
ATF_TC_BODY(attach_pid1_securelevel, tc)
{
int level;
size_t len = sizeof(level);
ATF_REQUIRE(sysctlbyname("kern.securelevel", &level, &len, NULL, 0)
!= -1);
if (level < 1) {
atf_tc_skip("Test must be run with securelevel >= 1");
}
ATF_REQUIRE_ERRNO(EPERM, ptrace(PT_ATTACH, 1, NULL, 0) == -1);
}
ATF_TC(attach_self);
ATF_TC_HEAD(attach_self, tc)
{
atf_tc_set_md_var(tc, "descr",
"Assert that a debugger cannot attach to self (as it's nonsense)");
}
ATF_TC_BODY(attach_self, tc)
{
ATF_REQUIRE_ERRNO(EINVAL, ptrace(PT_ATTACH, getpid(), NULL, 0) == -1);
}
ATF_TC(attach_chroot);
ATF_TC_HEAD(attach_chroot, tc)
{
atf_tc_set_md_var(tc, "descr",
"Assert that a debugger cannot trace another process unless the "
"process's root directory is at or below the tracing process's "
"root");
atf_tc_set_md_var(tc, "require.user", "root");
}
ATF_TC_BODY(attach_chroot, tc)
{
char buf[PATH_MAX];
pid_t child;
int fds_toparent[2], fds_fromparent[2];
int rv;
uint8_t msg = 0xde; /* dummy message for IPC based on pipe(2) */
(void)memset(buf, '\0', sizeof(buf));
ATF_REQUIRE(getcwd(buf, sizeof(buf)) != NULL);
(void)strlcat(buf, "/dir", sizeof(buf));
ATF_REQUIRE(mkdir(buf, 0500) == 0);
ATF_REQUIRE(chdir(buf) == 0);
ATF_REQUIRE(pipe(fds_toparent) == 0);
ATF_REQUIRE(pipe(fds_fromparent) == 0);
child = atf_utils_fork();
if (child == 0) {
FORKEE_ASSERT(close(fds_toparent[0]) == 0);
FORKEE_ASSERT(close(fds_fromparent[1]) == 0);
FORKEE_ASSERT(chroot(buf) == 0);
rv = write(fds_toparent[1], &msg, sizeof(msg));
FORKEE_ASSERTX(rv == sizeof(msg));
ATF_REQUIRE_ERRNO(EPERM,
ptrace(PT_ATTACH, getppid(), NULL, 0) == -1);
rv = read(fds_fromparent[0], &msg, sizeof(msg));
FORKEE_ASSERTX(rv == sizeof(msg));
_exit(0);
}
ATF_REQUIRE(close(fds_toparent[1]) == 0);
ATF_REQUIRE(close(fds_fromparent[0]) == 0);
printf("Waiting for chrooting of the child PID %d", child);
rv = read(fds_toparent[0], &msg, sizeof(msg));
ATF_REQUIRE(rv == sizeof(msg));
printf("Child is ready, it will try to PT_ATTACH to parent\n");
rv = write(fds_fromparent[1], &msg, sizeof(msg));
ATF_REQUIRE(rv == sizeof(msg));
printf("fds_fromparent is no longer needed - close it\n");
ATF_REQUIRE(close(fds_fromparent[1]) == 0);
printf("fds_toparent is no longer needed - close it\n");
ATF_REQUIRE(close(fds_toparent[0]) == 0);
}
ATF_TP_ADD_TCS(tp)
{
setvbuf(stdout, NULL, _IONBF, 0);
setvbuf(stderr, NULL, _IONBF, 0);
ATF_TP_ADD_TC(tp, attach_pid0);
ATF_TP_ADD_TC(tp, attach_pid1);
ATF_TP_ADD_TC(tp, attach_pid1_securelevel);
ATF_TP_ADD_TC(tp, attach_self);
ATF_TP_ADD_TC(tp, attach_chroot);
return atf_no_error();
}