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 
23 static int nerrs = 0;
24 
25 static 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 
38 static 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 
48 static jmp_buf jmpbuf;
49 
50 static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
51 {
52 	siglongjmp(jmpbuf, 1);
53 }
54 
55 static 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 
68 static 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 
78 static 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 
88 int 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