/* $NetBSD: t_sigstack.c,v 1.12.2.2 2024/08/23 16:56:29 martin Exp $ */ /*- * Copyright (c) 2024 The NetBSD Foundation, Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include __RCSID("$NetBSD: t_sigstack.c,v 1.12.2.2 2024/08/23 16:56:29 martin Exp $"); #include #include #include #include #include #include "h_macros.h" struct sigaltstack ss[3]; jmp_buf jmp; sigjmp_buf sigjmp; unsigned nentries; const char *bailname; void (*bailfn)(void) __dead; static void on_sigusr1(int signo, siginfo_t *si, void *ctx) { ucontext_t *uc = ctx; void *sp = (void *)(uintptr_t)_UC_MACHINE_SP(uc); void *fp = __builtin_frame_address(0); struct sigaltstack *ssp; /* * Ensure we haven't re-entered the signal handler too many * times. We should enter only twice. */ ATF_REQUIRE_MSG(nentries < 2, "%u recursive signal handler entries is too many in this test", nentries + 1); /* * Ensure that the signal handler was called in the alternate * signal stack. */ ssp = &ss[nentries]; ATF_REQUIRE_MSG((fp >= ssp->ss_sp && fp < (void *)((char *)ssp->ss_sp + ssp->ss_size)), "sigaltstack failed to take effect on entry %u --" " signal handler's frame pointer %p doesn't lie in sigaltstack" " [%p, %p), size 0x%zx", nentries, fp, ssp->ss_sp, (char *)ssp->ss_sp + ssp->ss_size, ssp->ss_size); /* * Ensure that if we enter the signal handler, we are entering * it from the original stack, not from any of the alternate * signal stacks. * * On some architectures, this is broken. Those that appear to * get this right are: * * aarch64 * alpha * arm * i386 * m68k * or1k * powerpc * powerpc64 * riscv * vax * x86_64 */ #if defined __hppa__ || \ defined __ia64__ || defined __mips__ || \ defined __sparc__ || defined __sparc64__ if (nentries > 0) atf_tc_expect_fail("PR lib/57946"); #endif for (ssp = &ss[0]; ssp < &ss[__arraycount(ss)]; ssp++) { ATF_REQUIRE_MSG((sp < ssp->ss_sp || sp >= (void *)((char *)ssp->ss_sp + ssp->ss_size)), "%s failed to restore stack" " before allowing signal on entry %u --" " interrupted stack pointer %p lies in sigaltstack %zd" " [%p, %p), size 0x%zx", bailname, nentries, sp, ssp - ss, ssp->ss_sp, (char *)ssp->ss_sp + ssp->ss_size, ssp->ss_size); } /* * First time through, we want to test whether longjmp restores * the signal mask first, or restores the stack pointer first. * The signal should be blocked at this point, so we re-raise * the signal to queue it up for delivery as soon as it is * unmasked -- which should wait until the stack pointer has * been restored in longjmp. */ if (nentries++ == 0) RL(raise(SIGUSR1)); /* * Set up the next sigaltstack. We can't reuse the current one * for the next signal handler re-entry until the system clears * the SS_ONSTACK process state -- which normal return from * signal handler does, but which longjmp does not. So to keep * it simple (ha), we just use another sigaltstack. */ RL(sigaltstack(&ss[nentries], NULL)); /* * Jump back to the original context. */ (*bailfn)(); } static void go(const char *name, void (*fn)(void) __dead) { struct sigaction sa; unsigned i; bailname = name; bailfn = fn; /* * Allocate a stack for the signal handler to run in, and * configure the system to use the first one. * * XXX Should maybe use a guard page but this is simpler. */ for (i = 0; i < __arraycount(ss); i++) { ss[i].ss_size = SIGSTKSZ; REQUIRE_LIBC(ss[i].ss_sp = malloc(ss[i].ss_size), NULL); } RL(sigaltstack(&ss[0], NULL)); /* * Set up a test signal handler for SIGUSR1. Allow all * signals, except SIGUSR1 (which is masked by default) -- that * way we don't inadvertently obscure weird crashes in the * signal handler. * * Set SA_SIGINFO so the system will pass siginfo -- and, more * to the point, ucontext, so the signal handler can determine * the stack pointer of the logic it interrupted. * * Set SA_ONSTACK so the system will use the alternate signal * stack to call the signal handler -- that way, it can tell * whether the stack was restored before the second time * around. */ memset(&sa, 0, sizeof(sa)); sa.sa_sigaction = &on_sigusr1; RL(sigemptyset(&sa.sa_mask)); sa.sa_flags = SA_SIGINFO|SA_ONSTACK; RL(sigaction(SIGUSR1, &sa, NULL)); /* * Raise the signal to enter the signal handler the first time. */ RL(raise(SIGUSR1)); /* * If we ever reach this point, something went seriously wrong. */ atf_tc_fail("unreachable"); } static void __dead bail_longjmp(void) { longjmp(jmp, 1); } ATF_TC(setjmp); ATF_TC_HEAD(setjmp, tc) { atf_tc_set_md_var(tc, "descr", "Test longjmp restores stack first, then signal mask"); } ATF_TC_BODY(setjmp, tc) { /* * Set up a return point for the signal handler: when the * signal handler does longjmp(jmp, 1), it comes flying out of * here. */ if (setjmp(jmp) == 1) return; /* * Run the test with longjmp. */ go("longjmp", &bail_longjmp); } static void __dead bail_siglongjmp(void) { siglongjmp(sigjmp, 1); } ATF_TC(sigsetjmp); ATF_TC_HEAD(sigsetjmp, tc) { atf_tc_set_md_var(tc, "descr", "Test siglongjmp restores stack first, then signal mask"); } ATF_TC_BODY(sigsetjmp, tc) { /* * Set up a return point for the signal handler: when the * signal handler does siglongjmp(sigjmp, 1), it comes flying * out of here. */ if (sigsetjmp(sigjmp, /*savesigmask*/1) == 1) return; /* * Run the test with siglongjmp. */ go("siglongjmp", &bail_siglongjmp); } ATF_TP_ADD_TCS(tp) { ATF_TP_ADD_TC(tp, setjmp); ATF_TP_ADD_TC(tp, sigsetjmp); return atf_no_error(); }