kern_core.c revision 1.36
1 /* $NetBSD: kern_core.c,v 1.36 2022/09/09 14:30:17 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 1.36 2022/09/09 14:30:17 christos Exp $"); 41 42 #ifdef _KERNEL_OPT 43 #include "opt_execfmt.h" 44 #include "opt_compat_netbsd32.h" 45 #endif 46 47 #include <sys/param.h> 48 #include <sys/vnode.h> 49 #include <sys/namei.h> 50 #include <sys/acct.h> 51 #include <sys/file.h> 52 #include <sys/stat.h> 53 #include <sys/proc.h> 54 #include <sys/exec.h> 55 #include <sys/filedesc.h> 56 #include <sys/kauth.h> 57 #include <sys/module.h> 58 #include <sys/compat_stub.h> 59 #include <sys/exec_elf.h> 60 61 MODULE(MODULE_CLASS_MISC, coredump, NULL); 62 63 struct coredump_iostate { 64 struct lwp *io_lwp; 65 struct vnode *io_vp; 66 kauth_cred_t io_cred; 67 off_t io_offset; 68 }; 69 70 static int coredump(struct lwp *, const char *); 71 static int coredump_buildname(struct proc *, char *, const char *, size_t); 72 static int coredump_write(struct coredump_iostate *, enum uio_seg segflg, 73 const void *, size_t); 74 static off_t coredump_offset(struct coredump_iostate *); 75 76 static int 77 coredump_modcmd(modcmd_t cmd, void *arg) 78 { 79 80 switch (cmd) { 81 case MODULE_CMD_INIT: 82 MODULE_HOOK_SET(coredump_hook, coredump); 83 MODULE_HOOK_SET(coredump_write_hook, coredump_write); 84 MODULE_HOOK_SET(coredump_offset_hook, coredump_offset); 85 MODULE_HOOK_SET(coredump_netbsd_hook, real_coredump_netbsd); 86 #if defined(EXEC_ELF64) 87 MODULE_HOOK_SET(coredump_elf64_hook, real_coredump_elf64); 88 #elif defined(EXEC_ELF32) 89 MODULE_HOOK_SET(coredump_elf32_hook, real_coredump_elf32); 90 #endif 91 MODULE_HOOK_SET(uvm_coredump_walkmap_hook, 92 uvm_coredump_walkmap); 93 MODULE_HOOK_SET(uvm_coredump_count_segs_hook, 94 uvm_coredump_count_segs); 95 return 0; 96 case MODULE_CMD_FINI: 97 MODULE_HOOK_UNSET(uvm_coredump_count_segs_hook); 98 MODULE_HOOK_UNSET(uvm_coredump_walkmap_hook); 99 #if defined(EXEC_ELF64) 100 MODULE_HOOK_UNSET(coredump_elf64_hook); 101 #elif defined(EXEC_ELF32) 102 MODULE_HOOK_UNSET(coredump_elf32_hook); 103 #endif 104 MODULE_HOOK_UNSET(coredump_netbsd_hook); 105 MODULE_HOOK_UNSET(coredump_offset_hook); 106 MODULE_HOOK_UNSET(coredump_write_hook); 107 MODULE_HOOK_UNSET(coredump_hook); 108 return 0; 109 default: 110 return ENOTTY; 111 } 112 } 113 114 /* 115 * Dump core, into a file named "progname.core" or "core" (depending on the 116 * value of shortcorename), unless the process was setuid/setgid. 117 */ 118 static int 119 coredump(struct lwp *l, const char *pattern) 120 { 121 struct vnode *vp; 122 struct proc *p; 123 struct vmspace *vm; 124 kauth_cred_t cred = NULL; 125 struct pathbuf *pb; 126 struct vattr vattr; 127 struct coredump_iostate io; 128 struct plimit *lim; 129 int error, error1; 130 char *name, *lastslash; 131 132 name = PNBUF_GET(); 133 134 p = l->l_proc; 135 vm = p->p_vmspace; 136 137 mutex_enter(&proc_lock); /* p_session */ 138 mutex_enter(p->p_lock); 139 140 /* 141 * Refuse to core if the data + stack + user size is larger than 142 * the core dump limit. XXX THIS IS WRONG, because of mapped 143 * data. 144 */ 145 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >= 146 p->p_rlimit[RLIMIT_CORE].rlim_cur) { 147 error = EFBIG; /* better error code? */ 148 goto release; 149 } 150 151 /* 152 * It may well not be curproc, so grab a reference to its current 153 * credentials. 154 */ 155 kauth_cred_hold(p->p_cred); 156 cred = p->p_cred; 157 158 /* 159 * Make sure the process has not set-id, to prevent data leaks, 160 * unless it was specifically requested to allow set-id coredumps. 161 */ 162 if (p->p_flag & PK_SUGID) { 163 if (!security_setidcore_dump) { 164 error = EPERM; 165 goto release; 166 } 167 pattern = security_setidcore_path; 168 } 169 170 /* Lock, as p_limit and pl_corename might change. */ 171 lim = p->p_limit; 172 mutex_enter(&lim->pl_lock); 173 if (pattern == NULL) { 174 pattern = lim->pl_corename; 175 } 176 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 177 mutex_exit(&lim->pl_lock); 178 179 if (error) 180 goto release; 181 182 /* 183 * On a simple filename, see if the filesystem allow us to write 184 * core dumps there. 185 */ 186 lastslash = strrchr(name, '/'); 187 if (!lastslash) { 188 vp = p->p_cwdi->cwdi_cdir; 189 if (vp->v_mount == NULL || 190 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 191 error = EPERM; 192 } 193 194 release: 195 mutex_exit(p->p_lock); 196 mutex_exit(&proc_lock); 197 if (error) 198 goto done; 199 200 /* 201 * On a complex filename, see if the filesystem allow us to write 202 * core dumps there. 203 * 204 * XXX: We should have an API that avoids double lookups 205 */ 206 if (lastslash) { 207 char c[2]; 208 209 if (lastslash - name >= MAXPATHLEN - 2) { 210 error = EPERM; 211 goto done; 212 } 213 214 c[0] = lastslash[1]; 215 c[1] = lastslash[2]; 216 lastslash[1] = '.'; 217 lastslash[2] = '\0'; 218 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 219 if (error) 220 goto done; 221 if (vp->v_mount == NULL || 222 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 223 error = EPERM; 224 vrele(vp); 225 if (error) 226 goto done; 227 lastslash[1] = c[0]; 228 lastslash[2] = c[1]; 229 } 230 231 pb = pathbuf_create(name); 232 if (pb == NULL) { 233 error = ENOMEM; 234 goto done; 235 } 236 error = vn_open(NULL, pb, 0, O_CREAT | O_NOFOLLOW | FWRITE, 237 S_IRUSR | S_IWUSR, &vp, NULL, NULL); 238 if (error != 0) { 239 pathbuf_destroy(pb); 240 goto done; 241 } 242 pathbuf_destroy(pb); 243 244 /* 245 * Don't dump to: 246 * - non-regular files 247 * - files with links 248 * - files we don't own 249 */ 250 if (vp->v_type != VREG || 251 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 252 vattr.va_uid != kauth_cred_geteuid(cred)) { 253 error = EACCES; 254 goto out; 255 } 256 vattr_null(&vattr); 257 vattr.va_size = 0; 258 259 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 260 vattr.va_uid = security_setidcore_owner; 261 vattr.va_gid = security_setidcore_group; 262 vattr.va_mode = security_setidcore_mode; 263 } 264 265 VOP_SETATTR(vp, &vattr, cred); 266 p->p_acflag |= ACORE; 267 268 io.io_lwp = l; 269 io.io_vp = vp; 270 io.io_cred = cred; 271 io.io_offset = 0; 272 273 /* Now dump the actual core file. */ 274 error = (*p->p_execsw->es_coredump)(l, &io); 275 out: 276 VOP_UNLOCK(vp); 277 error1 = vn_close(vp, FWRITE, cred); 278 if (error == 0) 279 error = error1; 280 done: 281 if (cred != NULL) 282 kauth_cred_free(cred); 283 if (name != NULL) 284 PNBUF_PUT(name); 285 return error; 286 } 287 288 static int 289 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 290 { 291 const char *s; 292 char *d, *end; 293 int i; 294 295 KASSERT(mutex_owned(&proc_lock)); 296 297 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 298 if (*s == '%') { 299 switch (*(s + 1)) { 300 case 'n': 301 i = snprintf(d, end - d, "%s", p->p_comm); 302 break; 303 case 'p': 304 i = snprintf(d, end - d, "%d", p->p_pid); 305 break; 306 case 'u': 307 i = snprintf(d, end - d, "%.*s", 308 (int)sizeof p->p_pgrp->pg_session->s_login, 309 p->p_pgrp->pg_session->s_login); 310 break; 311 case 't': 312 i = snprintf(d, end - d, "%lld", 313 (long long)p->p_stats->p_start.tv_sec); 314 break; 315 default: 316 goto copy; 317 } 318 d += i; 319 s++; 320 } else { 321 copy: *d = *s; 322 d++; 323 } 324 if (d >= end) 325 return (ENAMETOOLONG); 326 } 327 *d = '\0'; 328 return 0; 329 } 330 331 static int 332 coredump_write(struct coredump_iostate *io, enum uio_seg segflg, 333 const void *data, size_t len) 334 { 335 int error; 336 337 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 338 io->io_offset, segflg, 339 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 340 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 341 if (error) { 342 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 343 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 344 segflg == UIO_USERSPACE ? "user" : "system", 345 len, data, (long long) io->io_offset, error); 346 return (error); 347 } 348 349 io->io_offset += len; 350 return (0); 351 } 352 353 static off_t 354 coredump_offset(struct coredump_iostate *io) 355 { 356 return io->io_offset; 357 } 358
Indexes created Sun Sep 21 18:09:52 GMT 2025