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 return nerrs; 97 } 98