kern_core.c revision 1.29
1 /* $NetBSD: kern_core.c,v 1.29 2019/12/12 02:15:43 pgoyette 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 1.29 2019/12/12 02:15:43 pgoyette Exp $"); 41 42 #include <sys/param.h> 43 #include <sys/vnode.h> 44 #include <sys/namei.h> 45 #include <sys/acct.h> 46 #include <sys/file.h> 47 #include <sys/stat.h> 48 #include <sys/proc.h> 49 #include <sys/exec.h> 50 #include <sys/filedesc.h> 51 #include <sys/kauth.h> 52 #include <sys/module.h> 53 #include <sys/compat_stub.h> 54 55 MODULE(MODULE_CLASS_MISC, coredump, NULL); 56 57 struct coredump_iostate { 58 struct lwp *io_lwp; 59 struct vnode *io_vp; 60 kauth_cred_t io_cred; 61 off_t io_offset; 62 }; 63 64 static int coredump(struct lwp *, const char *); 65 static int coredump_buildname(struct proc *, char *, const char *, size_t); 66 static int coredump_write(struct coredump_iostate *, enum uio_seg segflg, 67 const void *, size_t); 68 static off_t coredump_offset(struct coredump_iostate *); 69 70 static int 71 coredump_modcmd(modcmd_t cmd, void *arg) 72 { 73 74 switch (cmd) { 75 case MODULE_CMD_INIT: 76 MODULE_HOOK_SET(coredump_hook, coredump); 77 MODULE_HOOK_SET(coredump_write_hook, coredump_write); 78 MODULE_HOOK_SET(coredump_offset_hook, coredump_offset); 79 MODULE_HOOK_SET(coredump_netbsd_hook, real_coredump_netbsd); 80 MODULE_HOOK_SET(uvm_coredump_walkmap_hook, 81 uvm_coredump_walkmap); 82 MODULE_HOOK_SET(uvm_coredump_count_segs_hook, 83 uvm_coredump_count_segs); 84 return 0; 85 case MODULE_CMD_FINI: 86 MODULE_HOOK_UNSET(uvm_coredump_count_segs_hook); 87 MODULE_HOOK_UNSET(uvm_coredump_walkmap_hook); 88 MODULE_HOOK_UNSET(coredump_netbsd_hook); 89 MODULE_HOOK_UNSET(coredump_offset_hook); 90 MODULE_HOOK_UNSET(coredump_write_hook); 91 MODULE_HOOK_UNSET(coredump_hook); 92 return 0; 93 default: 94 return ENOTTY; 95 } 96 } 97 98 /* 99 * Dump core, into a file named "progname.core" or "core" (depending on the 100 * value of shortcorename), unless the process was setuid/setgid. 101 */ 102 static int 103 coredump(struct lwp *l, const char *pattern) 104 { 105 struct vnode *vp; 106 struct proc *p; 107 struct vmspace *vm; 108 kauth_cred_t cred; 109 struct pathbuf *pb; 110 struct nameidata nd; 111 struct vattr vattr; 112 struct coredump_iostate io; 113 struct plimit *lim; 114 int error, error1; 115 char *name, *lastslash; 116 117 name = PNBUF_GET(); 118 119 p = l->l_proc; 120 vm = p->p_vmspace; 121 122 mutex_enter(proc_lock); /* p_session */ 123 mutex_enter(p->p_lock); 124 125 /* 126 * Refuse to core if the data + stack + user size is larger than 127 * the core dump limit. XXX THIS IS WRONG, because of mapped 128 * data. 129 */ 130 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >= 131 p->p_rlimit[RLIMIT_CORE].rlim_cur) { 132 error = EFBIG; /* better error code? */ 133 mutex_exit(p->p_lock); 134 mutex_exit(proc_lock); 135 goto done; 136 } 137 138 /* 139 * It may well not be curproc, so grab a reference to its current 140 * credentials. 141 */ 142 kauth_cred_hold(p->p_cred); 143 cred = p->p_cred; 144 145 /* 146 * Make sure the process has not set-id, to prevent data leaks, 147 * unless it was specifically requested to allow set-id coredumps. 148 */ 149 if (p->p_flag & PK_SUGID) { 150 if (!security_setidcore_dump) { 151 error = EPERM; 152 mutex_exit(p->p_lock); 153 mutex_exit(proc_lock); 154 goto done; 155 } 156 pattern = security_setidcore_path; 157 } 158 159 /* Lock, as p_limit and pl_corename might change. */ 160 lim = p->p_limit; 161 mutex_enter(&lim->pl_lock); 162 if (pattern == NULL) { 163 pattern = lim->pl_corename; 164 } 165 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 166 mutex_exit(&lim->pl_lock); 167 168 if (error) { 169 mutex_exit(p->p_lock); 170 mutex_exit(proc_lock); 171 goto done; 172 } 173 174 /* 175 * On a simple filename, see if the filesystem allow us to write 176 * core dumps there. 177 */ 178 lastslash = strrchr(name, '/'); 179 if (!lastslash) { 180 vp = p->p_cwdi->cwdi_cdir; 181 if (vp->v_mount == NULL || 182 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 183 error = EPERM; 184 } 185 186 mutex_exit(p->p_lock); 187 mutex_exit(proc_lock); 188 if (error) 189 goto done; 190 191 /* 192 * On a complex filename, see if the filesystem allow us to write 193 * core dumps there. 194 * 195 * XXX: We should have an API that avoids double lookups 196 */ 197 if (lastslash) { 198 char c[2]; 199 200 if (lastslash - name >= MAXPATHLEN - 2) { 201 error = EPERM; 202 goto done; 203 } 204 205 c[0] = lastslash[1]; 206 c[1] = lastslash[2]; 207 lastslash[1] = '.'; 208 lastslash[2] = '\0'; 209 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 210 if (error) 211 goto done; 212 if (vp->v_mount == NULL || 213 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 214 error = EPERM; 215 vrele(vp); 216 if (error) 217 goto done; 218 lastslash[1] = c[0]; 219 lastslash[2] = c[1]; 220 } 221 222 pb = pathbuf_create(name); 223 if (pb == NULL) { 224 error = ENOMEM; 225 goto done; 226 } 227 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 228 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 229 S_IRUSR | S_IWUSR)) != 0) { 230 pathbuf_destroy(pb); 231 goto done; 232 } 233 vp = nd.ni_vp; 234 pathbuf_destroy(pb); 235 236 /* 237 * Don't dump to: 238 * - non-regular files 239 * - files with links 240 * - files we don't own 241 */ 242 if (vp->v_type != VREG || 243 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 244 vattr.va_uid != kauth_cred_geteuid(cred)) { 245 error = EACCES; 246 goto out; 247 } 248 vattr_null(&vattr); 249 vattr.va_size = 0; 250 251 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 252 vattr.va_uid = security_setidcore_owner; 253 vattr.va_gid = security_setidcore_group; 254 vattr.va_mode = security_setidcore_mode; 255 } 256 257 VOP_SETATTR(vp, &vattr, cred); 258 p->p_acflag |= ACORE; 259 260 io.io_lwp = l; 261 io.io_vp = vp; 262 io.io_cred = cred; 263 io.io_offset = 0; 264 265 /* Now dump the actual core file. */ 266 error = (*p->p_execsw->es_coredump)(l, &io); 267 out: 268 VOP_UNLOCK(vp); 269 error1 = vn_close(vp, FWRITE, cred); 270 if (error == 0) 271 error = error1; 272 done: 273 if (name != NULL) 274 PNBUF_PUT(name); 275 return error; 276 } 277 278 static int 279 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 280 { 281 const char *s; 282 char *d, *end; 283 int i; 284 285 KASSERT(mutex_owned(proc_lock)); 286 287 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 288 if (*s == '%') { 289 switch (*(s + 1)) { 290 case 'n': 291 i = snprintf(d, end - d, "%s", p->p_comm); 292 break; 293 case 'p': 294 i = snprintf(d, end - d, "%d", p->p_pid); 295 break; 296 case 'u': 297 i = snprintf(d, end - d, "%.*s", 298 (int)sizeof p->p_pgrp->pg_session->s_login, 299 p->p_pgrp->pg_session->s_login); 300 break; 301 case 't': 302 i = snprintf(d, end - d, "%lld", 303 (long long)p->p_stats->p_start.tv_sec); 304 break; 305 default: 306 goto copy; 307 } 308 d += i; 309 s++; 310 } else { 311 copy: *d = *s; 312 d++; 313 } 314 if (d >= end) 315 return (ENAMETOOLONG); 316 } 317 *d = '\0'; 318 return 0; 319 } 320 321 static int 322 coredump_write(struct coredump_iostate *io, enum uio_seg segflg, 323 const void *data, size_t len) 324 { 325 int error; 326 327 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 328 io->io_offset, segflg, 329 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 330 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 331 if (error) { 332 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 333 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 334 segflg == UIO_USERSPACE ? "user" : "system", 335 len, data, (long long) io->io_offset, error); 336 return (error); 337 } 338 339 io->io_offset += len; 340 return (0); 341 } 342 343 static off_t 344 coredump_offset(struct coredump_iostate *io) 345 { 346 return io->io_offset; 347 } 348
Indexes created Sun Sep 21 20:09:37 GMT 2025