xref: /xnu-11215.81.4/tests/reply_port_defense.c (revision d4514f0bc1d3f944c22d92e68b646ac3fb40d452)

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <darwintest.h>
#include <spawn.h>
#include <mach/mach.h>
#include <sys/sysctl.h>
#include <signal.h>
#include "excserver_protect_state.h"
#include "../osfmk/ipc/ipc_init.h"
#include "../osfmk/mach/port.h"
#include "../osfmk/kern/exc_guard.h"
#include "exc_helpers.h"
#include <sys/code_signing.h>
#include "cs_helpers.h"
#include <TargetConditionals.h>

#define MAX_TEST_NUM 10
#define MAX_ARGV 3

extern char **environ;
static mach_exception_data_type_t received_exception_code = 0;
static exception_type_t exception_taken = 0;

/*
 * This test infrastructure is inspired from imm_pinned_control_port.c.
 * It verifies no reply port security semantics are violated.
 *
 * 1. The rcv right of the port would be marked immovable.
 */
T_GLOBAL_META(
	T_META_NAMESPACE("xnu.ipc"),
	T_META_RADAR_COMPONENT_NAME("xnu"),
	T_META_RADAR_COMPONENT_VERSION("IPC"),
	T_META_TIMEOUT(10),
	T_META_RUN_CONCURRENTLY(TRUE));

static mach_port_t
alloc_exception_port(void)
{
	kern_return_t kret;
	mach_port_t exc_port = MACH_PORT_NULL;
	mach_port_t task = mach_task_self();

	kret = mach_port_allocate(task, MACH_PORT_RIGHT_RECEIVE, &exc_port);
	T_QUIET; T_EXPECT_MACH_SUCCESS(kret, "mach_port_allocate exc_port");

	kret = mach_port_insert_right(task, exc_port, exc_port, MACH_MSG_TYPE_MAKE_SEND);
	T_QUIET; T_EXPECT_MACH_SUCCESS(kret, "mach_port_insert_right exc_port");

	return exc_port;
}

kern_return_t
catch_mach_exception_raise_state(mach_port_t exception_port,
    exception_type_t exception,
    const mach_exception_data_t code,
    mach_msg_type_number_t code_count,
    int * flavor,
    const thread_state_t old_state,
    mach_msg_type_number_t old_state_count,
    thread_state_t new_state,
    mach_msg_type_number_t * new_state_count)
{
#pragma unused(exception_port, exception, code, code_count, flavor, old_state, old_state_count, new_state, new_state_count)
	T_FAIL("Unsupported catch_mach_exception_raise_state");
	return KERN_NOT_SUPPORTED;
}

kern_return_t
catch_mach_exception_raise_state_identity(mach_port_t exception_port,
    mach_port_t thread,
    mach_port_t task,
    exception_type_t exception,
    mach_exception_data_t code,
    mach_msg_type_number_t code_count,
    int * flavor,
    thread_state_t old_state,
    mach_msg_type_number_t old_state_count,
    thread_state_t new_state,
    mach_msg_type_number_t * new_state_count)
{
#pragma unused(exception_port, thread, task, exception, code, code_count, flavor, old_state, old_state_count, new_state, new_state_count)
	T_FAIL("Unsupported catch_mach_exception_raise_state_identity");
	return KERN_NOT_SUPPORTED;
}

kern_return_t
catch_mach_exception_raise_state_identity_protected(
	__unused mach_port_t      exception_port,
	uint64_t                  thread_id,
	mach_port_t               task_id_token,
	exception_type_t          exception,
	mach_exception_data_t     codes,
	mach_msg_type_number_t    codeCnt,
	__unused int * flavor,
	__unused thread_state_t old_state,
	__unused mach_msg_type_number_t old_state_count,
	__unused thread_state_t new_state,
	__unused mach_msg_type_number_t * new_state_count)
{
#pragma unused(exception_port, thread_id, task_id_token, exception, codes, codeCnt)

	T_FAIL("Unsupported catch_mach_exception_raise_state_identity_protected");
	return KERN_NOT_SUPPORTED;
}

kern_return_t
catch_mach_exception_raise_identity_protected(
	__unused mach_port_t      exception_port,
	uint64_t                  thread_id,
	mach_port_t               task_id_token,
	exception_type_t          exception,
	mach_exception_data_t     codes,
	mach_msg_type_number_t    codeCnt)
{
#pragma unused(exception_port, thread_id, task_id_token)

	T_ASSERT_GT_UINT(codeCnt, 0, "CodeCnt");

	T_LOG("Caught exception type: %d code: 0x%llx", exception, codes[0]);
	exception_taken = exception;
	if (exception == EXC_GUARD) {
		received_exception_code = EXC_GUARD_DECODE_GUARD_FLAVOR((uint64_t)codes[0]);
	} else {
		T_FAIL("Unexpected exception");
	}
	return KERN_SUCCESS;
}

kern_return_t
catch_mach_exception_raise(mach_port_t exception_port,
    mach_port_t thread,
    mach_port_t task,
    exception_type_t exception,
    mach_exception_data_t code,
    mach_msg_type_number_t code_count)
{
#pragma unused(exception_port, thread, task, exception, code, code_count)
	T_FAIL("Unsupported catch_mach_exception_raise_state_identity");
	return KERN_NOT_SUPPORTED;
}

static void *
exception_server_thread(void *arg)
{
	kern_return_t kr;
	mach_port_t exc_port = *(mach_port_t *)arg;

	/* Handle exceptions on exc_port */
	kr = mach_msg_server_once(mach_exc_server, 4096, exc_port, 0);
	T_QUIET; T_EXPECT_MACH_SUCCESS(kr, "mach_msg_server_once");

	return NULL;
}

static void
reply_port_defense(const bool thirdparty_hardened, int test_index, mach_exception_data_type_t expected_exception_code, bool triggers_exception)
{
	int ret = 0;

	uint32_t task_exc_guard = 0;
	size_t te_size = sizeof(&task_exc_guard);

	/* Test that the behavior is the same between these two */
	char *test_prog_name = thirdparty_hardened ?
	    "./reply_port_defense_client_3P_hardened" : "./reply_port_defense_client";
	char *child_args[MAX_ARGV];
	pid_t client_pid = 0;
	posix_spawnattr_t attrs;

	pthread_t s_exc_thread;
	mach_port_t exc_port;

	T_LOG("Check if task_exc_guard exception has been enabled\n");
	ret = sysctlbyname("kern.task_exc_guard_default", &task_exc_guard, &te_size, NULL, 0);
	T_ASSERT_EQ(ret, 0, "sysctlbyname");

	if (!(task_exc_guard & TASK_EXC_GUARD_MP_DELIVER)) {
		T_SKIP("task_exc_guard exception is not enabled");
	}

	exc_port = alloc_exception_port();
	T_QUIET; T_ASSERT_NE(exc_port, MACH_PORT_NULL, "Create a new exception port");

	/* Create exception serving thread */
	ret = pthread_create(&s_exc_thread, NULL, exception_server_thread, &exc_port);
	T_QUIET; T_ASSERT_POSIX_SUCCESS(ret, "pthread_create exception_server_thread");

	/* Initialize posix_spawn attributes */
	posix_spawnattr_init(&attrs);

	/*
	 * It is allowed for us to set an exception port because we are entitled test process.
	 * If you are using this code as an example for platform binaries,
	 * use `EXCEPTION_IDENTITY_PROTECTED` instead of `EXCEPTION_DEFAULT`
	 */
	int err = posix_spawnattr_setexceptionports_np(&attrs, EXC_MASK_GUARD, exc_port,
	    (exception_behavior_t) (EXCEPTION_IDENTITY_PROTECTED | MACH_EXCEPTION_CODES), 0);
	T_QUIET; T_ASSERT_POSIX_SUCCESS(err, "posix_spawnattr_setflags");

	child_args[0] = test_prog_name;
	char test_num[10];
	sprintf(test_num, "%d", test_index);
	child_args[1] = test_num;
	child_args[2] = NULL;

	T_LOG("========== Spawning new child ==========");
	err = posix_spawn(&client_pid, child_args[0], NULL, &attrs, &child_args[0], environ);
	T_ASSERT_POSIX_SUCCESS(err, "posix_spawn reply_port_defense_client = %d", client_pid);

	int child_status;
	/* Wait for child and check for exception */
	if (-1 == waitpid(-1, &child_status, 0)) {
		T_FAIL("%s waitpid: child", strerror(errno));
	}
	if (WIFEXITED(child_status) && WEXITSTATUS(child_status)) {
		T_FAIL("Child exited with status = 0x%x", child_status);
	}
	sleep(1);
	kill(1, SIGKILL);
	if (triggers_exception) {
		ret = pthread_join(s_exc_thread, NULL);
		T_QUIET; T_ASSERT_POSIX_SUCCESS(ret, "pthread_join");
	}

	mach_port_deallocate(mach_task_self(), exc_port);

	T_LOG("Exception code: Received code = 0x%llx Expected code = 0x%llx", received_exception_code, expected_exception_code);
	T_EXPECT_EQ(received_exception_code, expected_exception_code, "Exception code: Received == Expected");
}

T_DECL(reply_port_defense,
    "Test reply port semantics violations",
    T_META_IGNORECRASHES(".*reply_port_defense_client.*"),
    T_META_CHECK_LEAKS(false),
    T_META_TAG_VM_NOT_PREFERRED) {
	bool triggers_exception = true;
	/* The first test is setup as moving immovable receive right of a reply port. */
	reply_port_defense(true, 0, kGUARD_EXC_IMMOVABLE, triggers_exception);
	reply_port_defense(false, 0, kGUARD_EXC_IMMOVABLE, triggers_exception);

	int rp_defense_max_test_idx = 3;
	/* Run the reply_port_defense tests 1, 2, and 3 */
	mach_exception_data_type_t expected_exception_code = kGUARD_EXC_INVALID_RIGHT;
	for (int i = 1; i <= rp_defense_max_test_idx; i++) {
		reply_port_defense(true, i, expected_exception_code, triggers_exception);
		reply_port_defense(false, i, expected_exception_code, triggers_exception);
	}
}


T_DECL(test_move_provisional_reply_port,
    "provisional reply ports are immovable",
    T_META_IGNORECRASHES(".*reply_port_defense_client.*"),
    T_META_CHECK_LEAKS(false)) {
	int test_num = 4;
	mach_exception_data_type_t expected_exception_code = 0;
	bool triggers_exception = false;
	reply_port_defense(true, test_num, expected_exception_code, triggers_exception);
	reply_port_defense(false, test_num, expected_exception_code, triggers_exception);
}

T_DECL(test_unentitled_thread_set_exception_ports,
    "thread_set_exception_ports should fail without an entitlement",
    T_META_IGNORECRASHES(".*reply_port_defense_client.*"),
    T_META_CHECK_LEAKS(false)) {
	int test_num = 5;
	mach_exception_data_type_t expected_exception_code = kGUARD_EXC_EXCEPTION_BEHAVIOR_ENFORCE;
	bool triggers_exception = true;

#if TARGET_OS_OSX
	T_SKIP("Test disabled on macOS due to SIP disabled and AMFI boot args usage on BATS");
	/*
	 * CS_CONFIG_GET_OUT_OF_MY_WAY (enabled via AMFI boot-args)
	 * disables this security feature. This boot-arg previously
	 * caused a headache for developers on macos, who frequently use it for
	 * testing purposes, because all of their 3rd party apps will
	 * crash due to being treated as platform code. Unfortunately
	 * BATS runs with this boot-arg enabled.
	 */
	code_signing_config_t cs_config = 0;
	size_t cs_config_size = sizeof(cs_config);
	sysctlbyname("security.codesigning.config", &cs_config, &cs_config_size, NULL, 0);
	if (cs_config & CS_CONFIG_GET_OUT_OF_MY_WAY) {
		expected_exception_code = 0;
		triggers_exception = false;
		T_LOG("task identity security policy for thread_set_exception_ports"
		    " disabled due to AMFI boot-args.");
	} else
#endif /* TARGET_OS_OSX */
	{
		T_LOG("task identity security policy for thread_set_exception_ports enabled");
	}

	reply_port_defense(true, test_num, expected_exception_code, triggers_exception);
	reply_port_defense(false, test_num, expected_exception_code, triggers_exception);
}

T_DECL(test_unentitled_thread_set_state,
    "thread_set_state should fail without an entitlement",
    T_META_IGNORECRASHES(".*reply_port_defense_client.*"),
    T_META_CHECK_LEAKS(false),
    T_META_ENABLED(false /* rdar://133955889 */))
{
	int test_num = 6;
	mach_exception_data_type_t expected_exception_code = (mach_exception_data_type_t)kGUARD_EXC_THREAD_SET_STATE;
	bool triggers_exception = true;

#if TARGET_OS_OSX
	T_SKIP("Test disabled on macOS due to mach hardening opt out");
#endif /* TARGET_OS_OSX */

	reply_port_defense(true, test_num, expected_exception_code, triggers_exception);
	reply_port_defense(false, test_num, expected_exception_code, triggers_exception);
}

T_DECL(unentitled_set_exception_ports_pass,
    "set_exception_ports should succeed",
    T_META_IGNORECRASHES(".*reply_port_defense_client.*"),
    T_META_CHECK_LEAKS(false)) {
	int test_num = 7;
	mach_exception_data_type_t expected_exception_code = (mach_exception_data_type_t)0;
	bool triggers_exception = false;
	reply_port_defense(true, test_num, expected_exception_code, triggers_exception);
	reply_port_defense(false, test_num, expected_exception_code, triggers_exception);
}


T_DECL(kobject_reply_port_defense,
    "sending messages to kobjects without a proper reply port should crash",
    T_META_IGNORECRASHES(".*reply_port_defense_client.*"),
    T_META_CHECK_LEAKS(false),
    T_META_ENABLED(!TARGET_OS_OSX)) {     /* disable on macOS due to BATS boot-args */
	int test_num = 9;
#if __x86_64__
	mach_exception_data_type_t expected_exception_code = (mach_exception_data_type_t)kGUARD_EXC_REQUIRE_REPLY_PORT_SEMANTICS;
#else
	mach_exception_data_type_t expected_exception_code = (mach_exception_data_type_t)kGUARD_EXC_SEND_INVALID_REPLY;
#endif
	bool triggers_exception = true;
	reply_port_defense(true, test_num, expected_exception_code, triggers_exception);
	reply_port_defense(false, test_num, expected_exception_code, triggers_exception);
}