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 42 static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void) 43 { 44 handler_called = 1; 45 } 46 47 static void handler_without_siginfo(int sig) 48 { 49 handler_called = 1; 50 } 51 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
