text: /*
   * 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;
  }
  