summaryrefslogtreecommitdiffstats
path: root/tools/testing/selftests/sigaltstack/sas.c
blob: 228c2ae47687dd753250e696456f7fcedb99b17a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
// SPDX-License-Identifier: GPL-2.0
/*
 * Stas Sergeev <stsp@users.sourceforge.net>
 *
 * test sigaltstack(SS_ONSTACK | SS_AUTODISARM)
 * If that succeeds, then swapcontext() can be used inside sighandler safely.
 *
 */

#define _GNU_SOURCE
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <ucontext.h>
#include <alloca.h>
#include <string.h>
#include <assert.h>
#include <errno.h>

#include "../kselftest.h"

#ifndef SS_AUTODISARM
#define SS_AUTODISARM  (1U << 31)
#endif

static void *sstack, *ustack;
static ucontext_t uc, sc;
static const char *msg = "[OK]\tStack preserved";
static const char *msg2 = "[FAIL]\tStack corrupted";
struct stk_data {
	char msg[128];
	int flag;
};

void my_usr1(int sig, siginfo_t *si, void *u)
{
	char *aa;
	int err;
	stack_t stk;
	struct stk_data *p;

#if __s390x__
	register unsigned long sp asm("%15");
#else
	register unsigned long sp asm("sp");
#endif

	if (sp < (unsigned long)sstack ||
			sp >= (unsigned long)sstack + SIGSTKSZ) {
		ksft_exit_fail_msg("SP is not on sigaltstack\n");
	}
	/* put some data on stack. other sighandler will try to overwrite it */
	aa = alloca(1024);
	assert(aa);
	p = (struct stk_data *)(aa + 512);
	strcpy(p->msg, msg);
	p->flag = 1;
	ksft_print_msg("[RUN]\tsignal USR1\n");
	err = sigaltstack(NULL, &stk);
	if (err) {
		ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
		exit(EXIT_FAILURE);
	}
	if (stk.ss_flags != SS_DISABLE)
		ksft_test_result_fail("tss_flags=%x, should be SS_DISABLE\n",
				stk.ss_flags);
	else
		ksft_test_result_pass(
				"sigaltstack is disabled in sighandler\n");
	swapcontext(&sc, &uc);
	ksft_print_msg("%s\n", p->msg);
	if (!p->flag) {
		ksft_exit_skip("[RUN]\tAborting\n");
		exit(EXIT_FAILURE);
	}
}

void my_usr2(int sig, siginfo_t *si, void *u)
{
	char *aa;
	struct stk_data *p;

	ksft_print_msg("[RUN]\tsignal USR2\n");
	aa = alloca(1024);
	/* dont run valgrind on this */
	/* try to find the data stored by previous sighandler */
	p = memmem(aa, 1024, msg, strlen(msg));
	if (p) {
		ksft_test_result_fail("sigaltstack re-used\n");
		/* corrupt the data */
		strcpy(p->msg, msg2);
		/* tell other sighandler that his data is corrupted */
		p->flag = 0;
	}
}

static void switch_fn(void)
{
	ksft_print_msg("[RUN]\tswitched to user ctx\n");
	raise(SIGUSR2);
	setcontext(&sc);
}

int main(void)
{
	struct sigaction act;
	stack_t stk;
	int err;

	ksft_print_header();

	sigemptyset(&act.sa_mask);
	act.sa_flags = SA_ONSTACK | SA_SIGINFO;
	act.sa_sigaction = my_usr1;
	sigaction(SIGUSR1, &act, NULL);
	act.sa_sigaction = my_usr2;
	sigaction(SIGUSR2, &act, NULL);
	sstack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
		      MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
	if (sstack == MAP_FAILED) {
		ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
		return EXIT_FAILURE;
	}

	err = sigaltstack(NULL, &stk);
	if (err) {
		ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
		exit(EXIT_FAILURE);
	}
	if (stk.ss_flags == SS_DISABLE) {
		ksft_test_result_pass(
				"Initial sigaltstack state was SS_DISABLE\n");
	} else {
		ksft_exit_fail_msg("Initial sigaltstack state was %x; "
		       "should have been SS_DISABLE\n", stk.ss_flags);
		return EXIT_FAILURE;
	}

	stk.ss_sp = sstack;
	stk.ss_size = SIGSTKSZ;
	stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;
	err = sigaltstack(&stk, NULL);
	if (err) {
		if (errno == EINVAL) {
			ksft_exit_skip(
				"[NOTE]\tThe running kernel doesn't support SS_AUTODISARM\n");
			/*
			 * If test cases for the !SS_AUTODISARM variant were
			 * added, we could still run them.  We don't have any
			 * test cases like that yet, so just exit and report
			 * success.
			 */
			return 0;
		} else {
			ksft_exit_fail_msg(
				"sigaltstack(SS_ONSTACK | SS_AUTODISARM)  %s\n",
					strerror(errno));
			return EXIT_FAILURE;
		}
	}

	ustack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
		      MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
	if (ustack == MAP_FAILED) {
		ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
		return EXIT_FAILURE;
	}
	getcontext(&uc);
	uc.uc_link = NULL;
	uc.uc_stack.ss_sp = ustack;
	uc.uc_stack.ss_size = SIGSTKSZ;
	makecontext(&uc, switch_fn, 0);
	raise(SIGUSR1);

	err = sigaltstack(NULL, &stk);
	if (err) {
		ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
		exit(EXIT_FAILURE);
	}
	if (stk.ss_flags != SS_AUTODISARM) {
		ksft_exit_fail_msg("ss_flags=%x, should be SS_AUTODISARM\n",
				stk.ss_flags);
		exit(EXIT_FAILURE);
	}
	ksft_test_result_pass(
			"sigaltstack is still SS_AUTODISARM after signal\n");

	ksft_exit_pass();
	return 0;
}