selftests/x86: Add a basic selftest for ioperm

.PHONY: all all_32 all_64 warn_32bit_failure clean

TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall test_mremap_vdso \

			check_initial_reg_state sigreturn ldt_gdt iopl mpx-mini-test \

			check_initial_reg_state sigreturn ldt_gdt iopl mpx-mini-test ioperm \

			protection_keys test_vdso

TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \

			test_FCMOV test_FCOMI test_FISTTP \

/*

 * ioperm.c - Test case for ioperm(2)

 * Copyright (c) 2015 Andrew Lutomirski

 */

#define _GNU_SOURCE

#include <err.h>

#include <stdio.h>

#include <stdint.h>

#include <signal.h>

#include <setjmp.h>

#include <stdlib.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <stdbool.h>

#include <sched.h>

#include <sys/io.h>

static int nerrs = 0;

static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),

		       int flags)

{

	struct sigaction sa;

	memset(&sa, 0, sizeof(sa));

	sa.sa_sigaction = handler;

	sa.sa_flags = SA_SIGINFO | flags;

	sigemptyset(&sa.sa_mask);

	if (sigaction(sig, &sa, 0))

		err(1, "sigaction");

}

static void clearhandler(int sig)

{

	struct sigaction sa;

	memset(&sa, 0, sizeof(sa));

	sa.sa_handler = SIG_DFL;

	sigemptyset(&sa.sa_mask);

	if (sigaction(sig, &sa, 0))

		err(1, "sigaction");

}

static jmp_buf jmpbuf;

static void sigsegv(int sig, siginfo_t *si, void *ctx_void)

{

	siglongjmp(jmpbuf, 1);

}

static bool try_outb(unsigned short port)

{

	sethandler(SIGSEGV, sigsegv, SA_RESETHAND);

	if (sigsetjmp(jmpbuf, 1) != 0) {

		return false;

	} else {

		asm volatile ("outb %%al, %w[port]"

			      : : [port] "Nd" (port), "a" (0));

		return true;

	}

	clearhandler(SIGSEGV);

}

static void expect_ok(unsigned short port)

{

	if (!try_outb(port)) {

		printf("[FAIL]\toutb to 0x%02hx failed\n", port);

		exit(1);

	}

	printf("[OK]\toutb to 0x%02hx worked\n", port);

}

static void expect_gp(unsigned short port)

{

	if (try_outb(port)) {

		printf("[FAIL]\toutb to 0x%02hx worked\n", port);

		exit(1);

	}

	printf("[OK]\toutb to 0x%02hx failed\n", port);

}

int main(void)

{

	cpu_set_t cpuset;

	CPU_ZERO(&cpuset);

	CPU_SET(0, &cpuset);

	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)

		err(1, "sched_setaffinity to CPU 0");

	expect_gp(0x80);

	expect_gp(0xed);

	/*

	 * Probe for ioperm support.  Note that clearing ioperm bits

	 * works even as nonroot.

	 */

	printf("[RUN]\tenable 0x80\n");

	if (ioperm(0x80, 1, 1) != 0) {

		printf("[OK]\tioperm(0x80, 1, 1) failed (%d) -- try running as root\n",

		       errno);

		return 0;

	}

	expect_ok(0x80);

	expect_gp(0xed);

	printf("[RUN]\tdisable 0x80\n");

	if (ioperm(0x80, 1, 0) != 0) {

		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);

		return 1;

	}

	expect_gp(0x80);

	expect_gp(0xed);

	/* Make sure that fork() preserves ioperm. */

	if (ioperm(0x80, 1, 1) != 0) {

		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);

		return 1;

	}

	pid_t child = fork();

	if (child == -1)

		err(1, "fork");

	if (child == 0) {

		printf("[RUN]\tchild: check that we inherited permissions\n");

		expect_ok(0x80);

		expect_gp(0xed);

		return 0;

	} else {

		int status;

		if (waitpid(child, &status, 0) != child ||

		    !WIFEXITED(status)) {

			printf("[FAIL]\tChild died\n");

			nerrs++;

		} else if (WEXITSTATUS(status) != 0) {

			printf("[FAIL]\tChild failed\n");

			nerrs++;

		} else {

			printf("[OK]\tChild succeeded\n");

		}

	}

	/* Test the capability checks. */

	printf("\tDrop privileges\n");

	if (setresuid(1, 1, 1) != 0) {

		printf("[WARN]\tDropping privileges failed\n");

		return 0;

	}

	printf("[RUN]\tdisable 0x80\n");

	if (ioperm(0x80, 1, 0) != 0) {

		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);

		return 1;

	}

	printf("[OK]\tit worked\n");

	printf("[RUN]\tenable 0x80 again\n");

	if (ioperm(0x80, 1, 1) == 0) {

		printf("[FAIL]\tit succeeded but should have failed.\n");

		return 1;

	}

	printf("[OK]\tit failed\n");

	return 0;

}