1 /* $NetBSD: getstack.c,v 1.1 2026/08/28 06:35:26 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2026 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __RCSID("$NetBSD: getstack.c,v 1.1 2026/08/28 06:35:26 riastradh Exp $"); 31 32 #include "getstack.h" 33 34 #include <sys/exec.h> 35 #include <sys/exec_elf.h> 36 #include <sys/resource.h> 37 #include <sys/sysctl.h> 38 #include <sys/types.h> 39 40 #include <dlfcn.h> 41 #include <err.h> 42 #include <pthread.h> 43 #include <signal.h> 44 #include <ucontext.h> 45 #include <unistd.h> 46 47 extern struct ps_strings *__ps_strings; /* XXX */ 48 49 void * 50 getstack_elf_auxv(void) 51 { 52 const AuxInfo *aux; 53 54 for (aux = _dlauxinfo(); aux->a_type != AT_NULL; aux++) { 55 if (aux->a_type == AT_STACKBASE) 56 return (void *)aux->a_v; 57 } 58 warnx("missing AT_STACKBASE in ELF auxv"); 59 return NULL; 60 } 61 62 void * 63 getstack_getcontext(size_t *usedsizep) 64 { 65 ucontext_t uc; 66 67 if (getcontext(&uc) == -1) { 68 warn("getcontext"); 69 *usedsizep = (size_t)-1; 70 return NULL; 71 } 72 *usedsizep = uc.uc_stack.ss_size; 73 return uc.uc_stack.ss_sp; 74 } 75 76 void * 77 getstack_psstrings(void) 78 { 79 80 if (__ps_strings == NULL) { 81 warnx("missing __ps_strings"); 82 return NULL; 83 } 84 85 #ifdef __MACHINE_STACK_GROWS_UP 86 return __ps_strings; 87 #else 88 return (char *)__ps_strings + sizeof(*__ps_strings); 89 #endif 90 } 91 92 void * 93 getstack_pthreadattr(size_t *minsizep) 94 { 95 pthread_attr_t attr_storage, *attr = NULL; 96 void *addr = NULL; 97 int error; 98 99 error = pthread_getattr_np(pthread_self(), &attr_storage); 100 if (error) { 101 warnc(error, "pthread_getattr_np"); 102 addr = NULL; 103 *minsizep = (size_t)-1; 104 goto out; 105 } 106 attr = &attr_storage; 107 108 error = pthread_attr_getstack(attr, &addr, minsizep); 109 if (error) { 110 warnc(error, "pthread_attr_getstack"); 111 addr = NULL; 112 *minsizep = (size_t)-1; 113 goto out; 114 } 115 116 #ifndef __MACHINE_STACK_GROWS_UP 117 addr = (char *)addr + *minsizep; 118 #endif 119 120 out: error = pthread_attr_destroy(attr); 121 if (error) 122 warnc(error, "pthread_attr_destroy"); 123 return addr; 124 } 125 126 void 127 getstack_rlimit(size_t *minsizep, size_t *maxsizep) 128 { 129 struct rlimit rlim; 130 131 if (getrlimit(RLIMIT_STACK, &rlim) == -1) { 132 warn("getrlimit(RLIMIT_STACK)"); 133 *minsizep = (size_t)-1; 134 *maxsizep = (size_t)-1; 135 return; 136 } 137 *minsizep = rlim.rlim_cur; 138 *maxsizep = rlim.rlim_max; 139 } 140 141 void * 142 getstack_sigaltstack(size_t *minsizep) 143 { 144 stack_t ss; 145 146 if (sigaltstack(NULL, &ss) == -1) { 147 warn("sigaltstack"); 148 *minsizep = (size_t)-1; 149 return NULL; 150 } 151 *minsizep = ss.ss_size; 152 return ss.ss_sp; 153 } 154 155 int 156 checkgetstack(void) 157 { 158 void *addr_elf_auxv; 159 void *addr_getcontext; 160 void *addr_psstrings; 161 void *addr_pthreadattr; 162 void *addr_sigaltstack; 163 size_t usedsize_getcontext; 164 size_t minsize_pthreadattr; 165 size_t minsize_rlimit; 166 size_t maxsize_rlimit; 167 size_t minsize_sigaltstack; 168 169 addr_elf_auxv = getstack_elf_auxv(); 170 addr_getcontext = getstack_getcontext(&usedsize_getcontext); 171 addr_psstrings = getstack_psstrings(); 172 addr_pthreadattr = getstack_pthreadattr(&minsize_pthreadattr); 173 getstack_rlimit(&minsize_rlimit, &maxsize_rlimit); 174 addr_sigaltstack = getstack_sigaltstack(&minsize_sigaltstack); 175 176 warnx("%16s: addr=%p", "ELF AT_STACKBASE", addr_elf_auxv); 177 warnx("%16s: addr=%-16p used=%zx", "getcontext", 178 addr_getcontext, usedsize_getcontext); 179 warnx("%16s: addr=%p", "__ps_strings", addr_psstrings); 180 warnx("%16s: addr=%-16p size=%zx", "pthread attr", 181 addr_pthreadattr, minsize_pthreadattr); 182 warnx("%16s: %-16s size=%zx min, %zx max", "RLIMIT_STACK", 183 "", minsize_rlimit, maxsize_rlimit); 184 warnx("%16s: addr=%-16p size=%zx", "sigaltstack", 185 addr_sigaltstack, minsize_sigaltstack); 186 187 if (addr_elf_auxv == addr_getcontext && 188 addr_elf_auxv == addr_psstrings && 189 addr_elf_auxv == addr_pthreadattr && 190 (addr_sigaltstack == NULL || addr_elf_auxv == addr_sigaltstack) && 191 usedsize_getcontext <= minsize_rlimit && 192 minsize_pthreadattr == minsize_rlimit && 193 (addr_sigaltstack == NULL || 194 minsize_pthreadattr == minsize_sigaltstack) && 195 minsize_rlimit <= maxsize_rlimit) { 196 warnx("Stack OK"); 197 return 0; 198 } 199 200 warnx("Stack disagreement!"); 201 return -1; 202 } 203 204 int 205 checkgetstack_singlethreaded(void) 206 { 207 void *addr_elf_auxv; 208 void *addr_getcontext; 209 void *addr_psstrings; 210 void *addr_sigaltstack; 211 size_t usedsize_getcontext; 212 size_t minsize_rlimit; 213 size_t maxsize_rlimit; 214 size_t minsize_sigaltstack; 215 216 addr_elf_auxv = getstack_elf_auxv(); 217 addr_getcontext = getstack_getcontext(&usedsize_getcontext); 218 addr_psstrings = getstack_psstrings(); 219 getstack_rlimit(&minsize_rlimit, &maxsize_rlimit); 220 addr_sigaltstack = getstack_sigaltstack(&minsize_sigaltstack); 221 222 warnx("%16s: addr=%p", "ELF AT_STACKBASE", addr_elf_auxv); 223 warnx("%16s: addr=%-16p used=%zx", "getcontext", 224 addr_getcontext, usedsize_getcontext); 225 warnx("%16s: addr=%p", "__ps_strings", addr_psstrings); 226 warnx("%16s: %-16s size=%zx min, %zx max", "RLIMIT_STACK", 227 "", minsize_rlimit, maxsize_rlimit); 228 warnx("%16s: addr=%-16p size=%zx", "sigaltstack", 229 addr_sigaltstack, minsize_sigaltstack); 230 231 if (addr_elf_auxv == addr_getcontext && 232 addr_elf_auxv == addr_psstrings && 233 (addr_sigaltstack == NULL || addr_elf_auxv == addr_sigaltstack) && 234 usedsize_getcontext <= minsize_rlimit && 235 (addr_sigaltstack == NULL || 236 minsize_rlimit == minsize_sigaltstack) && 237 minsize_rlimit <= maxsize_rlimit) { 238 warnx("Stack OK"); 239 return 0; 240 } 241 242 warnx("Stack disagreement!"); 243 return -1; 244 } 245
Indexes created Wed Sep 16 00:24:39 UTC 2026