1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * vdso_restorer.c - tests vDSO-based signal restore
4  * Copyright (c) 2015 Andrew Lutomirski
5  *
6  * This makes sure that sa_restorer == NULL keeps working on 32-bit
7  * configurations.  Modern glibc doesn't use it under any circumstances,
8  * so it's easy to overlook breakage.
9  *
10  * 64-bit userspace has never supported sa_restorer == NULL, so this is
11  * 32-bit only.
12  */
13 
14 #define _GNU_SOURCE
15 
16 #include <err.h>
17 #include <stdio.h>
18 #include <dlfcn.h>
19 #include <string.h>
20 #include <signal.h>
21 #include <unistd.h>
22 #include <syscall.h>
23 #include <sys/syscall.h>
24 
25 /* Open-code this -- the headers are too messy to easily use them. */
26 struct real_sigaction {
27 	void *handler;
28 	unsigned long flags;
29 	void *restorer;
30 	unsigned int mask[2];
31 };
32 
33 static volatile sig_atomic_t handler_called;
34 
35 static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
36 {
37 	handler_called = 1;
38 }
39 
40 static void handler_without_siginfo(int sig)
41 {
42 	handler_called = 1;
43 }
44 
45 int main()
46 {
47 	int nerrs = 0;
48 	struct real_sigaction sa;
49 
50 	void *vdso = dlopen("linux-vdso.so.1",
51 			    RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
52 	if (!vdso)
53 		vdso = dlopen("linux-gate.so.1",
54 			      RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
55 	if (!vdso) {
56 		printf("[SKIP]\tFailed to find vDSO.  Tests are not expected to work.\n");
57 		return 0;
58 	}
59 
60 	memset(&sa, 0, sizeof(sa));
61 	sa.handler = handler_with_siginfo;
62 	sa.flags = SA_SIGINFO;
63 	sa.restorer = NULL;	/* request kernel-provided restorer */
64 
65 	printf("[RUN]\tRaise a signal, SA_SIGINFO, sa.restorer == NULL\n");
66 
67 	if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
68 		err(1, "raw rt_sigaction syscall");
69 
70 	raise(SIGUSR1);
71 
72 	if (handler_called) {
73 		printf("[OK]\tSA_SIGINFO handler returned successfully\n");
74 	} else {
75 		printf("[FAIL]\tSA_SIGINFO handler was not called\n");
76 		nerrs++;
77 	}
78 
79 	printf("[RUN]\tRaise a signal, !SA_SIGINFO, sa.restorer == NULL\n");
80 
81 	sa.flags = 0;
82 	sa.handler = handler_without_siginfo;
83 	if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
84 		err(1, "raw sigaction syscall");
85 	handler_called = 0;
86 
87 	raise(SIGUSR1);
88 
89 	if (handler_called) {
90 		printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
91 	} else {
92 		printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
93 		nerrs++;
94 	}
95 }
96