tools/testing/selftests/x86/ioperm.c

   1 /*
   2  * ioperm.c - Test case for ioperm(2)
   3  * Copyright (c) 2015 Andrew Lutomirski
   4  */
   5
   6 #define _GNU_SOURCE
   7 #include <err.h>
   8 #include <stdio.h>
   9 #include <stdint.h>
  10 #include <signal.h>
  11 #include <setjmp.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <errno.h>
  15 #include <unistd.h>
  16 #include <sys/types.h>
  17 #include <sys/wait.h>
  18 #include <stdbool.h>
  19 #include <sched.h>
  20 #include <sys/io.h>
  21
  22 static int nerrs = 0;
  23
  24 static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
  25                        int flags)
  26 {
  27         struct sigaction sa;
  28         memset(&sa, 0, sizeof(sa));
  29         sa.sa_sigaction = handler;
  30         sa.sa_flags = SA_SIGINFO | flags;
  31         sigemptyset(&sa.sa_mask);
  32         if (sigaction(sig, &sa, 0))
  33                 err(1, "sigaction");
  34
  35 }
  36
  37 static void clearhandler(int sig)
  38 {
  39         struct sigaction sa;
  40         memset(&sa, 0, sizeof(sa));
  41         sa.sa_handler = SIG_DFL;
  42         sigemptyset(&sa.sa_mask);
  43         if (sigaction(sig, &sa, 0))
  44                 err(1, "sigaction");
  45 }
  46
  47 static jmp_buf jmpbuf;
  48
  49 static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
  50 {
  51         siglongjmp(jmpbuf, 1);
  52 }
  53
  54 static bool try_outb(unsigned short port)
  55 {
  56         sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
  57         if (sigsetjmp(jmpbuf, 1) != 0) {
  58                 return false;
  59         } else {
  60                 asm volatile ("outb %%al, %w[port]"
  61                               : : [port] "Nd" (port), "a" (0));
  62                 return true;
  63         }
  64         clearhandler(SIGSEGV);
  65 }
  66
  67 static void expect_ok(unsigned short port)
  68 {
  69         if (!try_outb(port)) {
  70                 printf("[FAIL]\toutb to 0x%02hx failed\n", port);
  71                 exit(1);
  72         }
  73
  74         printf("[OK]\toutb to 0x%02hx worked\n", port);
  75 }
  76
  77 static void expect_gp(unsigned short port)
  78 {
  79         if (try_outb(port)) {
  80                 printf("[FAIL]\toutb to 0x%02hx worked\n", port);
  81                 exit(1);
  82         }
  83
  84         printf("[OK]\toutb to 0x%02hx failed\n", port);
  85 }
  86
  87 int main(void)
  88 {
  89         cpu_set_t cpuset;
  90         CPU_ZERO(&cpuset);
  91         CPU_SET(0, &cpuset);
  92         if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
  93                 err(1, "sched_setaffinity to CPU 0");
  94
  95         expect_gp(0x80);
  96         expect_gp(0xed);
  97
  98         /*
  99          * Probe for ioperm support.  Note that clearing ioperm bits
 100          * works even as nonroot.
 101          */
 102         printf("[RUN]\tenable 0x80\n");
 103         if (ioperm(0x80, 1, 1) != 0) {
 104                 printf("[OK]\tioperm(0x80, 1, 1) failed (%d) -- try running as root\n",
 105                        errno);
 106                 return 0;
 107         }
 108         expect_ok(0x80);
 109         expect_gp(0xed);
 110
 111         printf("[RUN]\tdisable 0x80\n");
 112         if (ioperm(0x80, 1, 0) != 0) {
 113                 printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
 114                 return 1;
 115         }
 116         expect_gp(0x80);
 117         expect_gp(0xed);
 118
 119         /* Make sure that fork() preserves ioperm. */
 120         if (ioperm(0x80, 1, 1) != 0) {
 121                 printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
 122                 return 1;
 123         }
 124
 125         pid_t child = fork();
 126         if (child == -1)
 127                 err(1, "fork");
 128
 129         if (child == 0) {
 130                 printf("[RUN]\tchild: check that we inherited permissions\n");
 131                 expect_ok(0x80);
 132                 expect_gp(0xed);
 133                 return 0;
 134         } else {
 135                 int status;
 136                 if (waitpid(child, &status, 0) != child ||
 137                     !WIFEXITED(status)) {
 138                         printf("[FAIL]\tChild died\n");
 139                         nerrs++;
 140                 } else if (WEXITSTATUS(status) != 0) {
 141                         printf("[FAIL]\tChild failed\n");
 142                         nerrs++;
 143                 } else {
 144                         printf("[OK]\tChild succeeded\n");
 145                 }
 146         }
 147
 148         /* Test the capability checks. */
 149
 150         printf("\tDrop privileges\n");
 151         if (setresuid(1, 1, 1) != 0) {
 152                 printf("[WARN]\tDropping privileges failed\n");
 153                 return 0;
 154         }
 155
 156         printf("[RUN]\tdisable 0x80\n");
 157         if (ioperm(0x80, 1, 0) != 0) {
 158                 printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
 159                 return 1;
 160         }
 161         printf("[OK]\tit worked\n");
 162
 163         printf("[RUN]\tenable 0x80 again\n");
 164         if (ioperm(0x80, 1, 1) == 0) {
 165                 printf("[FAIL]\tit succeeded but should have failed.\n");
 166                 return 1;
 167         }
 168         printf("[OK]\tit failed\n");
 169         return 0;
 170 }