LXR linux/tools/testing/selftests/x86/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
  23static int nerrs = 0;
  24
  25static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
  26                       int flags)
  27{
  28        struct sigaction sa;
  29        memset(&sa, 0, sizeof(sa));
  30        sa.sa_sigaction = handler;
  31        sa.sa_flags = SA_SIGINFO | flags;
  32        sigemptyset(&sa.sa_mask);
  33        if (sigaction(sig, &sa, 0))
  34                err(1, "sigaction");
  35
  36}
  37
  38static void clearhandler(int sig)
  39{
  40        struct sigaction sa;
  41        memset(&sa, 0, sizeof(sa));
  42        sa.sa_handler = SIG_DFL;
  43        sigemptyset(&sa.sa_mask);
  44        if (sigaction(sig, &sa, 0))
  45                err(1, "sigaction");
  46}
  47
  48static jmp_buf jmpbuf;
  49
  50static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
  51{
  52        siglongjmp(jmpbuf, 1);
  53}
  54
  55static bool try_outb(unsigned short port)
  56{
  57        sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
  58        if (sigsetjmp(jmpbuf, 1) != 0) {
  59                return false;
  60        } else {
  61                asm volatile ("outb %%al, %w[port]"
  62                              : : [port] "Nd" (port), "a" (0));
  63                return true;
  64        }
  65        clearhandler(SIGSEGV);
  66}
  67
  68static void expect_ok(unsigned short port)
  69{
  70        if (!try_outb(port)) {
  71                printf("[FAIL]\toutb to 0x%02hx failed\n", port);
  72                exit(1);
  73        }
  74
  75        printf("[OK]\toutb to 0x%02hx worked\n", port);
  76}
  77
  78static void expect_gp(unsigned short port)
  79{
  80        if (try_outb(port)) {
  81                printf("[FAIL]\toutb to 0x%02hx worked\n", port);
  82                exit(1);
  83        }
  84
  85        printf("[OK]\toutb to 0x%02hx failed\n", port);
  86}
  87
  88int main(void)
  89{
  90        cpu_set_t cpuset;
  91        CPU_ZERO(&cpuset);
  92        CPU_SET(0, &cpuset);
  93        if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
  94                err(1, "sched_setaffinity to CPU 0");
  95
  96        expect_gp(0x80);
  97        expect_gp(0xed);
  98
  99        /*
 100         * Probe for ioperm support.  Note that clearing ioperm bits
 101         * works even as nonroot.
 102         */
 103        printf("[RUN]\tenable 0x80\n");
 104        if (ioperm(0x80, 1, 1) != 0) {
 105                printf("[OK]\tioperm(0x80, 1, 1) failed (%d) -- try running as root\n",
 106                       errno);
 107                return 0;
 108        }
 109        expect_ok(0x80);
 110        expect_gp(0xed);
 111
 112        printf("[RUN]\tdisable 0x80\n");
 113        if (ioperm(0x80, 1, 0) != 0) {
 114                printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
 115                return 1;
 116        }
 117        expect_gp(0x80);
 118        expect_gp(0xed);
 119
 120        /* Make sure that fork() preserves ioperm. */
 121        if (ioperm(0x80, 1, 1) != 0) {
 122                printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
 123                return 1;
 124        }
 125
 126        pid_t child = fork();
 127        if (child == -1)
 128                err(1, "fork");
 129
 130        if (child == 0) {
 131                printf("[RUN]\tchild: check that we inherited permissions\n");
 132                expect_ok(0x80);
 133                expect_gp(0xed);
 134                return 0;
 135        } else {
 136                int status;
 137                if (waitpid(child, &status, 0) != child ||
 138                    !WIFEXITED(status)) {
 139                        printf("[FAIL]\tChild died\n");
 140                        nerrs++;
 141                } else if (WEXITSTATUS(status) != 0) {
 142                        printf("[FAIL]\tChild failed\n");
 143                        nerrs++;
 144                } else {
 145                        printf("[OK]\tChild succeeded\n");
 146                }
 147        }
 148
 149        /* Test the capability checks. */
 150
 151        printf("\tDrop privileges\n");
 152        if (setresuid(1, 1, 1) != 0) {
 153                printf("[WARN]\tDropping privileges failed\n");
 154                return 0;
 155        }
 156
 157        printf("[RUN]\tdisable 0x80\n");
 158        if (ioperm(0x80, 1, 0) != 0) {
 159                printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
 160                return 1;
 161        }
 162        printf("[OK]\tit worked\n");
 163
 164        printf("[RUN]\tenable 0x80 again\n");
 165        if (ioperm(0x80, 1, 1) == 0) {
 166                printf("[FAIL]\tit succeeded but should have failed.\n");
 167                return 1;
 168        }
 169        printf("[OK]\tit failed\n");
 170        return 0;
 171}
 172