// SPDX-License-Identifier: GPL-2.0-only /* * vdso_restorer.c - tests vDSO-based signal restore * Copyright (c) 2015 Andrew Lutomirski * * This makes sure that sa_restorer == NULL keeps working on 32-bit * configurations. Modern glibc doesn't use it under any circumstances, * so it's easy to overlook breakage. * * 64-bit userspace has never supported sa_restorer == NULL, so this is * 32-bit only. */ #define _GNU_SOURCE #include <err.h> #include <stdio.h> #include <dlfcn.h> #include <string.h> #include <signal.h> #include <unistd.h> #include <syscall.h> #include <sys/syscall.h> /* Open-code this -- the headers are too messy to easily use them. */ struct real_sigaction { void *handler; unsigned long flags; void *restorer; unsigned int mask[2]; }; static volatile sig_atomic_t handler_called; static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void) { handler_called = 1; } static void handler_without_siginfo(int sig) { handler_called = 1; } int main() { int nerrs = 0; struct real_sigaction sa; void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); if (!vdso) vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); if (!vdso) { printf("[SKIP]\tFailed to find vDSO. Tests are not expected to work.\n"); return 0; } memset(&sa, 0, sizeof(sa)); sa.handler = handler_with_siginfo; sa.flags = SA_SIGINFO; sa.restorer = NULL; /* request kernel-provided restorer */ printf("[RUN]\tRaise a signal, SA_SIGINFO, sa.restorer == NULL\n"); if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0) err(1, "raw rt_sigaction syscall"); raise(SIGUSR1); if (handler_called) { printf("[OK]\tSA_SIGINFO handler returned successfully\n"); } else { printf("[FAIL]\tSA_SIGINFO handler was not called\n"); nerrs++; } printf("[RUN]\tRaise a signal, !SA_SIGINFO, sa.restorer == NULL\n"); sa.flags = 0; sa.handler = handler_without_siginfo; if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0) err(1, "raw sigaction syscall"); handler_called = 0; raise(SIGUSR1); if (handler_called) { printf("[OK]\t!SA_SIGINFO handler returned successfully\n"); } else { printf("[FAIL]\t!SA_SIGINFO handler was not called\n"); nerrs++; } return nerrs; }