kern_core.c revision 1.32
1 /* $NetBSD: kern_core.c,v 1.32 2020/10/20 13:47:30 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1989, 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)kern_sig.c 8.14 (Berkeley) 5/14/95 37 */ 38 39 #include <sys/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: kern_core.c,v 1.32 2020/10/20 13:47:30 christos Exp $"); 41 42 #ifdef _KERNEL_OPT 43 #include "opt_compat_netbsd32.h" 44 #endif 45 46 #include <sys/param.h> 47 #include <sys/vnode.h> 48 #include <sys/namei.h> 49 #include <sys/acct.h> 50 #include <sys/file.h> 51 #include <sys/stat.h> 52 #include <sys/proc.h> 53 #include <sys/exec.h> 54 #include <sys/filedesc.h> 55 #include <sys/kauth.h> 56 #include <sys/module.h> 57 #include <sys/compat_stub.h> 58 #include <sys/exec_elf.h> 59 60 #ifdef COMPAT_NETBSD32 61 #define COREDUMP_MODULE_DEP "compat_netbsd32_ptrace" 62 #else 63 #define COREDUMP_MODULE_DEP NULL 64 #endif 65 66 MODULE(MODULE_CLASS_MISC, coredump, COREDUMP_MODULE_DEP); 67 68 struct coredump_iostate { 69 struct lwp *io_lwp; 70 struct vnode *io_vp; 71 kauth_cred_t io_cred; 72 off_t io_offset; 73 }; 74 75 static int coredump(struct lwp *, const char *); 76 static int coredump_buildname(struct proc *, char *, const char *, size_t); 77 static int coredump_write(struct coredump_iostate *, enum uio_seg segflg, 78 const void *, size_t); 79 static off_t coredump_offset(struct coredump_iostate *); 80 81 static int 82 coredump_modcmd(modcmd_t cmd, void *arg) 83 { 84 85 switch (cmd) { 86 case MODULE_CMD_INIT: 87 MODULE_HOOK_SET(coredump_hook, coredump); 88 MODULE_HOOK_SET(coredump_write_hook, coredump_write); 89 MODULE_HOOK_SET(coredump_offset_hook, coredump_offset); 90 MODULE_HOOK_SET(coredump_netbsd_hook, real_coredump_netbsd); 91 #if !defined(_LP64) || defined(COMPAT_NETBSD32) 92 MODULE_HOOK_SET(coredump_elf32_hook, real_coredump_elf32); 93 #endif 94 #ifdef _LP64 95 MODULE_HOOK_SET(coredump_elf64_hook, real_coredump_elf64); 96 #endif 97 MODULE_HOOK_SET(uvm_coredump_walkmap_hook, 98 uvm_coredump_walkmap); 99 MODULE_HOOK_SET(uvm_coredump_count_segs_hook, 100 uvm_coredump_count_segs); 101 return 0; 102 case MODULE_CMD_FINI: 103 MODULE_HOOK_UNSET(uvm_coredump_count_segs_hook); 104 MODULE_HOOK_UNSET(uvm_coredump_walkmap_hook); 105 #ifdef _LP64 106 MODULE_HOOK_UNSET(coredump_elf64_hook); 107 #endif 108 #if !defined(_LP64) || defined(COMPAT_NETBSD32) 109 MODULE_HOOK_UNSET(coredump_elf32_hook); 110 #endif 111 MODULE_HOOK_UNSET(coredump_netbsd_hook); 112 MODULE_HOOK_UNSET(coredump_offset_hook); 113 MODULE_HOOK_UNSET(coredump_write_hook); 114 MODULE_HOOK_UNSET(coredump_hook); 115 return 0; 116 default: 117 return ENOTTY; 118 } 119 } 120 121 /* 122 * Dump core, into a file named "progname.core" or "core" (depending on the 123 * value of shortcorename), unless the process was setuid/setgid. 124 */ 125 static int 126 coredump(struct lwp *l, const char *pattern) 127 { 128 struct vnode *vp; 129 struct proc *p; 130 struct vmspace *vm; 131 kauth_cred_t cred; 132 struct pathbuf *pb; 133 struct nameidata nd; 134 struct vattr vattr; 135 struct coredump_iostate io; 136 struct plimit *lim; 137 int error, error1; 138 char *name, *lastslash; 139 140 name = PNBUF_GET(); 141 142 p = l->l_proc; 143 vm = p->p_vmspace; 144 145 mutex_enter(&proc_lock); /* p_session */ 146 mutex_enter(p->p_lock); 147 148 /* 149 * Refuse to core if the data + stack + user size is larger than 150 * the core dump limit. XXX THIS IS WRONG, because of mapped 151 * data. 152 */ 153 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >= 154 p->p_rlimit[RLIMIT_CORE].rlim_cur) { 155 error = EFBIG; /* better error code? */ 156 mutex_exit(p->p_lock); 157 mutex_exit(&proc_lock); 158 goto done; 159 } 160 161 /* 162 * It may well not be curproc, so grab a reference to its current 163 * credentials. 164 */ 165 kauth_cred_hold(p->p_cred); 166 cred = p->p_cred; 167 168 /* 169 * Make sure the process has not set-id, to prevent data leaks, 170 * unless it was specifically requested to allow set-id coredumps. 171 */ 172 if (p->p_flag & PK_SUGID) { 173 if (!security_setidcore_dump) { 174 error = EPERM; 175 mutex_exit(p->p_lock); 176 mutex_exit(&proc_lock); 177 goto done; 178 } 179 pattern = security_setidcore_path; 180 } 181 182 /* Lock, as p_limit and pl_corename might change. */ 183 lim = p->p_limit; 184 mutex_enter(&lim->pl_lock); 185 if (pattern == NULL) { 186 pattern = lim->pl_corename; 187 } 188 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 189 mutex_exit(&lim->pl_lock); 190 191 if (error) { 192 mutex_exit(p->p_lock); 193 mutex_exit(&proc_lock); 194 goto done; 195 } 196 197 /* 198 * On a simple filename, see if the filesystem allow us to write 199 * core dumps there. 200 */ 201 lastslash = strrchr(name, '/'); 202 if (!lastslash) { 203 vp = p->p_cwdi->cwdi_cdir; 204 if (vp->v_mount == NULL || 205 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 206 error = EPERM; 207 } 208 209 mutex_exit(p->p_lock); 210 mutex_exit(&proc_lock); 211 if (error) 212 goto done; 213 214 /* 215 * On a complex filename, see if the filesystem allow us to write 216 * core dumps there. 217 * 218 * XXX: We should have an API that avoids double lookups 219 */ 220 if (lastslash) { 221 char c[2]; 222 223 if (lastslash - name >= MAXPATHLEN - 2) { 224 error = EPERM; 225 goto done; 226 } 227 228 c[0] = lastslash[1]; 229 c[1] = lastslash[2]; 230 lastslash[1] = '.'; 231 lastslash[2] = '\0'; 232 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 233 if (error) 234 goto done; 235 if (vp->v_mount == NULL || 236 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 237 error = EPERM; 238 vrele(vp); 239 if (error) 240 goto done; 241 lastslash[1] = c[0]; 242 lastslash[2] = c[1]; 243 } 244 245 pb = pathbuf_create(name); 246 if (pb == NULL) { 247 error = ENOMEM; 248 goto done; 249 } 250 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 251 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 252 S_IRUSR | S_IWUSR)) != 0) { 253 pathbuf_destroy(pb); 254 goto done; 255 } 256 vp = nd.ni_vp; 257 pathbuf_destroy(pb); 258 259 /* 260 * Don't dump to: 261 * - non-regular files 262 * - files with links 263 * - files we don't own 264 */ 265 if (vp->v_type != VREG || 266 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 267 vattr.va_uid != kauth_cred_geteuid(cred)) { 268 error = EACCES; 269 goto out; 270 } 271 vattr_null(&vattr); 272 vattr.va_size = 0; 273 274 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 275 vattr.va_uid = security_setidcore_owner; 276 vattr.va_gid = security_setidcore_group; 277 vattr.va_mode = security_setidcore_mode; 278 } 279 280 VOP_SETATTR(vp, &vattr, cred); 281 p->p_acflag |= ACORE; 282 283 io.io_lwp = l; 284 io.io_vp = vp; 285 io.io_cred = cred; 286 io.io_offset = 0; 287 288 /* Now dump the actual core file. */ 289 error = (*p->p_execsw->es_coredump)(l, &io); 290 out: 291 VOP_UNLOCK(vp); 292 error1 = vn_close(vp, FWRITE, cred); 293 if (error == 0) 294 error = error1; 295 done: 296 if (name != NULL) 297 PNBUF_PUT(name); 298 return error; 299 } 300 301 static int 302 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 303 { 304 const char *s; 305 char *d, *end; 306 int i; 307 308 KASSERT(mutex_owned(&proc_lock)); 309 310 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 311 if (*s == '%') { 312 switch (*(s + 1)) { 313 case 'n': 314 i = snprintf(d, end - d, "%s", p->p_comm); 315 break; 316 case 'p': 317 i = snprintf(d, end - d, "%d", p->p_pid); 318 break; 319 case 'u': 320 i = snprintf(d, end - d, "%.*s", 321 (int)sizeof p->p_pgrp->pg_session->s_login, 322 p->p_pgrp->pg_session->s_login); 323 break; 324 case 't': 325 i = snprintf(d, end - d, "%lld", 326 (long long)p->p_stats->p_start.tv_sec); 327 break; 328 default: 329 goto copy; 330 } 331 d += i; 332 s++; 333 } else { 334 copy: *d = *s; 335 d++; 336 } 337 if (d >= end) 338 return (ENAMETOOLONG); 339 } 340 *d = '\0'; 341 return 0; 342 } 343 344 static int 345 coredump_write(struct coredump_iostate *io, enum uio_seg segflg, 346 const void *data, size_t len) 347 { 348 int error; 349 350 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 351 io->io_offset, segflg, 352 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 353 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 354 if (error) { 355 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 356 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 357 segflg == UIO_USERSPACE ? "user" : "system", 358 len, data, (long long) io->io_offset, error); 359 return (error); 360 } 361 362 io->io_offset += len; 363 return (0); 364 } 365 366 static off_t 367 coredump_offset(struct coredump_iostate *io) 368 { 369 return io->io_offset; 370 } 371
Indexes created Sun Sep 21 20:09:37 GMT 2025