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		printf("[RUN]\tchild: Extend permissions to 0x81\n");
135		if (ioperm(0x81, 1, 1) != 0) {
136			printf("[FAIL]\tioperm(0x81, 1, 1) failed (%d)", errno);
137			return 1;
138		}
139		printf("[RUN]\tchild: Drop permissions to 0x80\n");
140		if (ioperm(0x80, 1, 0) != 0) {
141			printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
142			return 1;
143		}
144		expect_gp(0x80);
145		return 0;
146	} else {
147		int status;
148		if (waitpid(child, &status, 0) != child ||
149		    !WIFEXITED(status)) {
150			printf("[FAIL]\tChild died\n");
151			nerrs++;
152		} else if (WEXITSTATUS(status) != 0) {
153			printf("[FAIL]\tChild failed\n");
154			nerrs++;
155		} else {
156			printf("[OK]\tChild succeeded\n");
157		}
158	}
159
160	/* Verify that the child dropping 0x80 did not affect the parent */
161	printf("\tVerify that unsharing the bitmap worked\n");
162	expect_ok(0x80);
163
164	/* Test the capability checks. */
165	printf("\tDrop privileges\n");
166	if (setresuid(1, 1, 1) != 0) {
167		printf("[WARN]\tDropping privileges failed\n");
168		return 0;
169	}
170
171	printf("[RUN]\tdisable 0x80\n");
172	if (ioperm(0x80, 1, 0) != 0) {
173		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
174		return 1;
175	}
176	printf("[OK]\tit worked\n");
177
178	printf("[RUN]\tenable 0x80 again\n");
179	if (ioperm(0x80, 1, 1) == 0) {
180		printf("[FAIL]\tit succeeded but should have failed.\n");
181		return 1;
182	}
183	printf("[OK]\tit failed\n");
184	return 0;
185}
186