[deliverable/linux.git] / tools / testing / selftests / x86 / iopl.c

/*
 * iopl.c - Test case for a Linux on Xen 64-bit bug
 * 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 jmp_buf jmpbuf;

static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
{
	siglongjmp(jmpbuf, 1);
}

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");

	/* Probe for iopl support.  Note that iopl(0) works even as nonroot. */
	if (iopl(3) != 0) {
		printf("[OK]\tiopl(3) failed (%d) -- try running as root\n",
		       errno);
		return 0;
	}

	/* Restore our original state prior to starting the test. */
	if (iopl(0) != 0)
		err(1, "iopl(0)");

	pid_t child = fork();
	if (child == -1)
		err(1, "fork");

	if (child == 0) {
		printf("\tchild: set IOPL to 3\n");
		if (iopl(3) != 0)
			err(1, "iopl");

		printf("[RUN]\tchild: write to 0x80\n");
		asm volatile ("outb %%al, $0x80" : : "a" (0));

		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");
		}
	}

	printf("[RUN]\tparent: write to 0x80 (should fail)\n");

	sethandler(SIGSEGV, sigsegv, 0);
	if (sigsetjmp(jmpbuf, 1) != 0) {
		printf("[OK]\twrite was denied\n");
	} else {
		asm volatile ("outb %%al, $0x80" : : "a" (0));
		printf("[FAIL]\twrite was allowed\n");
		nerrs++;
	}

	/* Test the capability checks. */
	printf("\tiopl(3)\n");
	if (iopl(3) != 0)
		err(1, "iopl(3)");

	printf("\tDrop privileges\n");
	if (setresuid(1, 1, 1) != 0) {
		printf("[WARN]\tDropping privileges failed\n");
		goto done;
	}

	printf("[RUN]\tiopl(3) unprivileged but with IOPL==3\n");
	if (iopl(3) != 0) {
		printf("[FAIL]\tiopl(3) should work if iopl is already 3 even if unprivileged\n");
		nerrs++;
	}

	printf("[RUN]\tiopl(0) unprivileged\n");
	if (iopl(0) != 0) {
		printf("[FAIL]\tiopl(0) should work if iopl is already 3 even if unprivileged\n");
		nerrs++;
	}

	printf("[RUN]\tiopl(3) unprivileged\n");
	if (iopl(3) == 0) {
		printf("[FAIL]\tiopl(3) should fail if when unprivileged if iopl==0\n");
		nerrs++;
	} else {
		printf("[OK]\tFailed as expected\n");
	}

done:
	return nerrs ? 1 : 0;
}
Commit	Line	Data
b0898301 AL	1	/*
	2	* iopl.c - Test case for a Linux on Xen 64-bit bug
	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 jmp_buf jmpbuf;
	38
	39	static void sigsegv(int sig, siginfo_t si, void ctx_void)
	40	{
	41	siglongjmp(jmpbuf, 1);
	42	}
	43
	44	int main(void)
	45	{
	46	cpu_set_t cpuset;
	47	CPU_ZERO(&cpuset);
	48	CPU_SET(0, &cpuset);
	49	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
	50	err(1, "sched_setaffinity to CPU 0");
	51
	52	/* Probe for iopl support. Note that iopl(0) works even as nonroot. */
	53	if (iopl(3) != 0) {
	54	printf("[OK]\tiopl(3) failed (%d) -- try running as root\n",
	55	errno);
	56	return 0;
	57	}
	58
	59	/* Restore our original state prior to starting the test. */
	60	if (iopl(0) != 0)
	61	err(1, "iopl(0)");
	62
	63	pid_t child = fork();
	64	if (child == -1)
65	err(1, "fork");
66
67	if (child == 0) {
68	printf("\tchild: set IOPL to 3\n");
69	if (iopl(3) != 0)
70	err(1, "iopl");
71
72	printf("[RUN]\tchild: write to 0x80\n");
73	asm volatile ("outb %%al, $0x80" : : "a" (0));
74
75	return 0;
76	} else {
77	int status;
78	if (waitpid(child, &status, 0) != child \|\|
79	!WIFEXITED(status)) {
80	printf("[FAIL]\tChild died\n");
81	nerrs++;
82	} else if (WEXITSTATUS(status) != 0) {
83	printf("[FAIL]\tChild failed\n");
84	nerrs++;
85	} else {
86	printf("[OK]\tChild succeeded\n");
87	}
88	}
89
90	printf("[RUN]\tparent: write to 0x80 (should fail)\n");
91
92	sethandler(SIGSEGV, sigsegv, 0);
93	if (sigsetjmp(jmpbuf, 1) != 0) {
94	printf("[OK]\twrite was denied\n");
95	} else {
96	asm volatile ("outb %%al, $0x80" : : "a" (0));
97	printf("[FAIL]\twrite was allowed\n");
98	nerrs++;
99	}
100
101	/* Test the capability checks. */
102	printf("\tiopl(3)\n");
103	if (iopl(3) != 0)
104	err(1, "iopl(3)");
105
106	printf("\tDrop privileges\n");
107	if (setresuid(1, 1, 1) != 0) {
108	printf("[WARN]\tDropping privileges failed\n");
109	goto done;
110	}
111
112	printf("[RUN]\tiopl(3) unprivileged but with IOPL==3\n");
113	if (iopl(3) != 0) {
114	printf("[FAIL]\tiopl(3) should work if iopl is already 3 even if unprivileged\n");
115	nerrs++;
116	}
117
118	printf("[RUN]\tiopl(0) unprivileged\n");
119	if (iopl(0) != 0) {
120	printf("[FAIL]\tiopl(0) should work if iopl is already 3 even if unprivileged\n");
121	nerrs++;
122	}
123
124	printf("[RUN]\tiopl(3) unprivileged\n");
125	if (iopl(3) == 0) {
126	printf("[FAIL]\tiopl(3) should fail if when unprivileged if iopl==0\n");
127	nerrs++;
128	} else {
129	printf("[OK]\tFailed as expected\n");
130	}
131
132	done:
133	return nerrs ? 1 : 0;
134	}
135