ioperm.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * ioperm.c - Test case for ioperm(2)
  4 * Copyright (c) 2015 Andrew Lutomirski
  5 */
  6
  7#define _GNU_SOURCE
  8#include <err.h>
  9#include <stdio.h>
 10#include <stdint.h>
 11#include <signal.h>
 12#include <setjmp.h>
 13#include <stdlib.h>
 14#include <string.h>
 15#include <errno.h>
 16#include <unistd.h>
 17#include <sys/types.h>
 18#include <sys/wait.h>
 19#include <stdbool.h>
 20#include <sched.h>
 21#include <sys/io.h>
 22
 23#include "helpers.h"
 24
 25static int nerrs = 0;
 26
 27static jmp_buf jmpbuf;
 28
 29static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
 30{
 31	siglongjmp(jmpbuf, 1);
 32}
 33
 34static bool try_outb(unsigned short port)
 35{
 36	sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
 37	if (sigsetjmp(jmpbuf, 1) != 0) {
 38		return false;
 39	} else {
 40		asm volatile ("outb %%al, %w[port]"
 41			      : : [port] "Nd" (port), "a" (0));
 42		return true;
 43	}
 44	clearhandler(SIGSEGV);
 45}
 46
 47static void expect_ok(unsigned short port)
 48{
 49	if (!try_outb(port)) {
 50		printf("[FAIL]\toutb to 0x%02hx failed\n", port);
 51		exit(1);
 52	}
 53
 54	printf("[OK]\toutb to 0x%02hx worked\n", port);
 55}
 56
 57static void expect_gp(unsigned short port)
 58{
 59	if (try_outb(port)) {
 60		printf("[FAIL]\toutb to 0x%02hx worked\n", port);
 61		exit(1);
 62	}
 63
 64	printf("[OK]\toutb to 0x%02hx failed\n", port);
 65}
 66
 67int main(void)
 68{
 69	cpu_set_t cpuset;
 70	CPU_ZERO(&cpuset);
 71	CPU_SET(0, &cpuset);
 72	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
 73		err(1, "sched_setaffinity to CPU 0");
 74
 75	expect_gp(0x80);
 76	expect_gp(0xed);
 77
 78	/*
 79	 * Probe for ioperm support.  Note that clearing ioperm bits
 80	 * works even as nonroot.
 81	 */
 82	printf("[RUN]\tenable 0x80\n");
 83	if (ioperm(0x80, 1, 1) != 0) {
 84		printf("[OK]\tioperm(0x80, 1, 1) failed (%d) -- try running as root\n",
 85		       errno);
 86		return 0;
 87	}
 88	expect_ok(0x80);
 89	expect_gp(0xed);
 90
 91	printf("[RUN]\tdisable 0x80\n");
 92	if (ioperm(0x80, 1, 0) != 0) {
 93		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
 94		return 1;
 95	}
 96	expect_gp(0x80);
 97	expect_gp(0xed);
 98
 99	/* Make sure that fork() preserves ioperm. */
100	if (ioperm(0x80, 1, 1) != 0) {
101		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
102		return 1;
103	}
104
105	pid_t child = fork();
106	if (child == -1)
107		err(1, "fork");
108
109	if (child == 0) {
110		printf("[RUN]\tchild: check that we inherited permissions\n");
111		expect_ok(0x80);
112		expect_gp(0xed);
113		printf("[RUN]\tchild: Extend permissions to 0x81\n");
114		if (ioperm(0x81, 1, 1) != 0) {
115			printf("[FAIL]\tioperm(0x81, 1, 1) failed (%d)", errno);
116			return 1;
117		}
118		printf("[RUN]\tchild: Drop permissions to 0x80\n");
119		if (ioperm(0x80, 1, 0) != 0) {
120			printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
121			return 1;
122		}
123		expect_gp(0x80);
124		return 0;
125	} else {
126		int status;
127		if (waitpid(child, &status, 0) != child ||
128		    !WIFEXITED(status)) {
129			printf("[FAIL]\tChild died\n");
130			nerrs++;
131		} else if (WEXITSTATUS(status) != 0) {
132			printf("[FAIL]\tChild failed\n");
133			nerrs++;
134		} else {
135			printf("[OK]\tChild succeeded\n");
136		}
137	}
138
139	/* Verify that the child dropping 0x80 did not affect the parent */
140	printf("\tVerify that unsharing the bitmap worked\n");
141	expect_ok(0x80);
142
143	/* Test the capability checks. */
144	printf("\tDrop privileges\n");
145	if (setresuid(1, 1, 1) != 0) {
146		printf("[WARN]\tDropping privileges failed\n");
147		return 0;
148	}
149
150	printf("[RUN]\tdisable 0x80\n");
151	if (ioperm(0x80, 1, 0) != 0) {
152		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
153		return 1;
154	}
155	printf("[OK]\tit worked\n");
156
157	printf("[RUN]\tenable 0x80 again\n");
158	if (ioperm(0x80, 1, 1) == 0) {
159		printf("[FAIL]\tit succeeded but should have failed.\n");
160		return 1;
161	}
162	printf("[OK]\tit failed\n");
163	return 0;
164}