1 /*
2 * vdso_restorer.c - tests vDSO-based signal restore
3 * Copyright (c) 2015 Andrew Lutomirski
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * This makes sure that sa_restorer == NULL keeps working on 32-bit
15 * configurations. Modern glibc doesn't use it under any circumstances,
16 * so it's easy to overlook breakage.
17 *
18 * 64-bit userspace has never supported sa_restorer == NULL, so this is
19 * 32-bit only.
20 */
21
22 #define _GNU_SOURCE
23
24 #include <err.h>
25 #include <stdio.h>
26 #include <string.h>
27 #include <signal.h>
28 #include <unistd.h>
29 #include <syscall.h>
30 #include <sys/syscall.h>
31
32 /* Open-code this -- the headers are too messy to easily use them. */
33 struct real_sigaction {
34 void *handler;
35 unsigned long flags;
36 void *restorer;
37 unsigned int mask[2];
38 };
39
40 static volatile sig_atomic_t handler_called;
41
handler_with_siginfo(int sig,siginfo_t * info,void * ctx_void)42 static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
43 {
44 handler_called = 1;
45 }
46
handler_without_siginfo(int sig)47 static void handler_without_siginfo(int sig)
48 {
49 handler_called = 1;
50 }
51
main()52 int main()
53 {
54 int nerrs = 0;
55 struct real_sigaction sa;
56
57 memset(&sa, 0, sizeof(sa));
58 sa.handler = handler_with_siginfo;
59 sa.flags = SA_SIGINFO;
60 sa.restorer = NULL; /* request kernel-provided restorer */
61
62 if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
63 err(1, "raw rt_sigaction syscall");
64
65 raise(SIGUSR1);
66
67 if (handler_called) {
68 printf("[OK]\tSA_SIGINFO handler returned successfully\n");
69 } else {
70 printf("[FAIL]\tSA_SIGINFO handler was not called\n");
71 nerrs++;
72 }
73
74 sa.flags = 0;
75 sa.handler = handler_without_siginfo;
76 if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
77 err(1, "raw sigaction syscall");
78 handler_called = 0;
79
80 raise(SIGUSR1);
81
82 if (handler_called) {
83 printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
84 } else {
85 printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
86 nerrs++;
87 }
88 }
89