kern_core.c revision 1.31
1 /* $NetBSD: kern_core.c,v 1.31 2020/10/19 19:33:02 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 1.31 2020/10/19 19:33:02 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 MODULE_HOOK_SET(coredump_elf32_hook, real_coredump_elf32); 92 #ifdef _LP64 93 MODULE_HOOK_SET(coredump_elf64_hook, real_coredump_elf64); 94 #endif 95 MODULE_HOOK_SET(uvm_coredump_walkmap_hook, 96 uvm_coredump_walkmap); 97 MODULE_HOOK_SET(uvm_coredump_count_segs_hook, 98 uvm_coredump_count_segs); 99 return 0; 100 case MODULE_CMD_FINI: 101 MODULE_HOOK_UNSET(uvm_coredump_count_segs_hook); 102 MODULE_HOOK_UNSET(uvm_coredump_walkmap_hook); 103 #ifdef _LP64 104 MODULE_HOOK_UNSET(coredump_elf64_hook); 105 #endif 106 MODULE_HOOK_UNSET(coredump_elf32_hook); 107 MODULE_HOOK_UNSET(coredump_netbsd_hook); 108 MODULE_HOOK_UNSET(coredump_offset_hook); 109 MODULE_HOOK_UNSET(coredump_write_hook); 110 MODULE_HOOK_UNSET(coredump_hook); 111 return 0; 112 default: 113 return ENOTTY; 114 } 115 } 116 117 /* 118 * Dump core, into a file named "progname.core" or "core" (depending on the 119 * value of shortcorename), unless the process was setuid/setgid. 120 */ 121 static int 122 coredump(struct lwp *l, const char *pattern) 123 { 124 struct vnode *vp; 125 struct proc *p; 126 struct vmspace *vm; 127 kauth_cred_t cred; 128 struct pathbuf *pb; 129 struct nameidata nd; 130 struct vattr vattr; 131 struct coredump_iostate io; 132 struct plimit *lim; 133 int error, error1; 134 char *name, *lastslash; 135 136 name = PNBUF_GET(); 137 138 p = l->l_proc; 139 vm = p->p_vmspace; 140 141 mutex_enter(&proc_lock); /* p_session */ 142 mutex_enter(p->p_lock); 143 144 /* 145 * Refuse to core if the data + stack + user size is larger than 146 * the core dump limit. XXX THIS IS WRONG, because of mapped 147 * data. 148 */ 149 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >= 150 p->p_rlimit[RLIMIT_CORE].rlim_cur) { 151 error = EFBIG; /* better error code? */ 152 mutex_exit(p->p_lock); 153 mutex_exit(&proc_lock); 154 goto done; 155 } 156 157 /* 158 * It may well not be curproc, so grab a reference to its current 159 * credentials. 160 */ 161 kauth_cred_hold(p->p_cred); 162 cred = p->p_cred; 163 164 /* 165 * Make sure the process has not set-id, to prevent data leaks, 166 * unless it was specifically requested to allow set-id coredumps. 167 */ 168 if (p->p_flag & PK_SUGID) { 169 if (!security_setidcore_dump) { 170 error = EPERM; 171 mutex_exit(p->p_lock); 172 mutex_exit(&proc_lock); 173 goto done; 174 } 175 pattern = security_setidcore_path; 176 } 177 178 /* Lock, as p_limit and pl_corename might change. */ 179 lim = p->p_limit; 180 mutex_enter(&lim->pl_lock); 181 if (pattern == NULL) { 182 pattern = lim->pl_corename; 183 } 184 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 185 mutex_exit(&lim->pl_lock); 186 187 if (error) { 188 mutex_exit(p->p_lock); 189 mutex_exit(&proc_lock); 190 goto done; 191 } 192 193 /* 194 * On a simple filename, see if the filesystem allow us to write 195 * core dumps there. 196 */ 197 lastslash = strrchr(name, '/'); 198 if (!lastslash) { 199 vp = p->p_cwdi->cwdi_cdir; 200 if (vp->v_mount == NULL || 201 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 202 error = EPERM; 203 } 204 205 mutex_exit(p->p_lock); 206 mutex_exit(&proc_lock); 207 if (error) 208 goto done; 209 210 /* 211 * On a complex filename, see if the filesystem allow us to write 212 * core dumps there. 213 * 214 * XXX: We should have an API that avoids double lookups 215 */ 216 if (lastslash) { 217 char c[2]; 218 219 if (lastslash - name >= MAXPATHLEN - 2) { 220 error = EPERM; 221 goto done; 222 } 223 224 c[0] = lastslash[1]; 225 c[1] = lastslash[2]; 226 lastslash[1] = '.'; 227 lastslash[2] = '\0'; 228 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 229 if (error) 230 goto done; 231 if (vp->v_mount == NULL || 232 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 233 error = EPERM; 234 vrele(vp); 235 if (error) 236 goto done; 237 lastslash[1] = c[0]; 238 lastslash[2] = c[1]; 239 } 240 241 pb = pathbuf_create(name); 242 if (pb == NULL) { 243 error = ENOMEM; 244 goto done; 245 } 246 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 247 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 248 S_IRUSR | S_IWUSR)) != 0) { 249 pathbuf_destroy(pb); 250 goto done; 251 } 252 vp = nd.ni_vp; 253 pathbuf_destroy(pb); 254 255 /* 256 * Don't dump to: 257 * - non-regular files 258 * - files with links 259 * - files we don't own 260 */ 261 if (vp->v_type != VREG || 262 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 263 vattr.va_uid != kauth_cred_geteuid(cred)) { 264 error = EACCES; 265 goto out; 266 } 267 vattr_null(&vattr); 268 vattr.va_size = 0; 269 270 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 271 vattr.va_uid = security_setidcore_owner; 272 vattr.va_gid = security_setidcore_group; 273 vattr.va_mode = security_setidcore_mode; 274 } 275 276 VOP_SETATTR(vp, &vattr, cred); 277 p->p_acflag |= ACORE; 278 279 io.io_lwp = l; 280 io.io_vp = vp; 281 io.io_cred = cred; 282 io.io_offset = 0; 283 284 /* Now dump the actual core file. */ 285 error = (*p->p_execsw->es_coredump)(l, &io); 286 out: 287 VOP_UNLOCK(vp); 288 error1 = vn_close(vp, FWRITE, cred); 289 if (error == 0) 290 error = error1; 291 done: 292 if (name != NULL) 293 PNBUF_PUT(name); 294 return error; 295 } 296 297 static int 298 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 299 { 300 const char *s; 301 char *d, *end; 302 int i; 303 304 KASSERT(mutex_owned(&proc_lock)); 305 306 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 307 if (*s == '%') { 308 switch (*(s + 1)) { 309 case 'n': 310 i = snprintf(d, end - d, "%s", p->p_comm); 311 break; 312 case 'p': 313 i = snprintf(d, end - d, "%d", p->p_pid); 314 break; 315 case 'u': 316 i = snprintf(d, end - d, "%.*s", 317 (int)sizeof p->p_pgrp->pg_session->s_login, 318 p->p_pgrp->pg_session->s_login); 319 break; 320 case 't': 321 i = snprintf(d, end - d, "%lld", 322 (long long)p->p_stats->p_start.tv_sec); 323 break; 324 default: 325 goto copy; 326 } 327 d += i; 328 s++; 329 } else { 330 copy: *d = *s; 331 d++; 332 } 333 if (d >= end) 334 return (ENAMETOOLONG); 335 } 336 *d = '\0'; 337 return 0; 338 } 339 340 static int 341 coredump_write(struct coredump_iostate *io, enum uio_seg segflg, 342 const void *data, size_t len) 343 { 344 int error; 345 346 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 347 io->io_offset, segflg, 348 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 349 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 350 if (error) { 351 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 352 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 353 segflg == UIO_USERSPACE ? "user" : "system", 354 len, data, (long long) io->io_offset, error); 355 return (error); 356 } 357 358 io->io_offset += len; 359 return (0); 360 } 361 362 static off_t 363 coredump_offset(struct coredump_iostate *io) 364 { 365 return io->io_offset; 366 } 367
Indexes created Sun Sep 21 18:09:52 GMT 2025