1 /* $NetBSD: kern_core.c,v 1.24 2016/07/07 06:55:43 msaitoh 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 1.24 2016/07/07 06:55:43 msaitoh 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 54 MODULE(MODULE_CLASS_MISC, coredump, NULL); 55 56 struct coredump_iostate { 57 struct lwp *io_lwp; 58 struct vnode *io_vp; 59 kauth_cred_t io_cred; 60 off_t io_offset; 61 }; 62 63 static int coredump(struct lwp *, const char *); 64 static int coredump_buildname(struct proc *, char *, const char *, size_t); 65 66 static int 67 coredump_modcmd(modcmd_t cmd, void *arg) 68 { 69 70 switch (cmd) { 71 case MODULE_CMD_INIT: 72 coredump_vec = coredump; 73 return 0; 74 case MODULE_CMD_FINI: 75 /* 76 * In theory we don't need to patch this, as the various 77 * exec formats depend on this module. If this module has 78 * no references, and so can be unloaded, no user programs 79 * can be running and so nothing can call *coredump_vec. 80 */ 81 coredump_vec = (int (*)(struct lwp *, const char *))enosys; 82 return 0; 83 default: 84 return ENOTTY; 85 } 86 } 87 88 /* 89 * Dump core, into a file named "progname.core" or "core" (depending on the 90 * value of shortcorename), unless the process was setuid/setgid. 91 */ 92 static int 93 coredump(struct lwp *l, const char *pattern) 94 { 95 struct vnode *vp; 96 struct proc *p; 97 struct vmspace *vm; 98 kauth_cred_t cred; 99 struct pathbuf *pb; 100 struct nameidata nd; 101 struct vattr vattr; 102 struct coredump_iostate io; 103 struct plimit *lim; 104 int error, error1; 105 char *name, *lastslash; 106 107 name = PNBUF_GET(); 108 109 p = l->l_proc; 110 vm = p->p_vmspace; 111 112 mutex_enter(proc_lock); /* p_session */ 113 mutex_enter(p->p_lock); 114 115 /* 116 * Refuse to core if the data + stack + user size is larger than 117 * the core dump limit. XXX THIS IS WRONG, because of mapped 118 * data. 119 */ 120 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >= 121 p->p_rlimit[RLIMIT_CORE].rlim_cur) { 122 error = EFBIG; /* better error code? */ 123 mutex_exit(p->p_lock); 124 mutex_exit(proc_lock); 125 goto done; 126 } 127 128 /* 129 * It may well not be curproc, so grab a reference to its current 130 * credentials. 131 */ 132 kauth_cred_hold(p->p_cred); 133 cred = p->p_cred; 134 135 /* 136 * Make sure the process has not set-id, to prevent data leaks, 137 * unless it was specifically requested to allow set-id coredumps. 138 */ 139 if (p->p_flag & PK_SUGID) { 140 if (!security_setidcore_dump) { 141 error = EPERM; 142 mutex_exit(p->p_lock); 143 mutex_exit(proc_lock); 144 goto done; 145 } 146 pattern = security_setidcore_path; 147 } 148 149 /* Lock, as p_limit and pl_corename might change. */ 150 lim = p->p_limit; 151 mutex_enter(&lim->pl_lock); 152 if (pattern == NULL) { 153 pattern = lim->pl_corename; 154 } 155 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 156 mutex_exit(&lim->pl_lock); 157 158 if (error) { 159 mutex_exit(p->p_lock); 160 mutex_exit(proc_lock); 161 goto done; 162 } 163 164 /* 165 * On a simple filename, see if the filesystem allow us to write 166 * core dumps there. 167 */ 168 lastslash = strrchr(name, '/'); 169 if (!lastslash) { 170 vp = p->p_cwdi->cwdi_cdir; 171 if (vp->v_mount == NULL || 172 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 173 error = EPERM; 174 } 175 176 mutex_exit(p->p_lock); 177 mutex_exit(proc_lock); 178 if (error) 179 goto done; 180 181 /* 182 * On a complex filename, see if the filesystem allow us to write 183 * core dumps there. 184 * 185 * XXX: We should have an API that avoids double lookups 186 */ 187 if (lastslash) { 188 char c[2]; 189 190 if (lastslash - name >= MAXPATHLEN - 2) { 191 error = EPERM; 192 goto done; 193 } 194 195 c[0] = lastslash[1]; 196 c[1] = lastslash[2]; 197 lastslash[1] = '.'; 198 lastslash[2] = '\0'; 199 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 200 if (error) 201 goto done; 202 if (vp->v_mount == NULL || 203 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 204 error = EPERM; 205 vrele(vp); 206 if (error) 207 goto done; 208 lastslash[1] = c[0]; 209 lastslash[2] = c[1]; 210 } 211 212 pb = pathbuf_create(name); 213 if (pb == NULL) { 214 error = ENOMEM; 215 goto done; 216 } 217 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 218 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 219 S_IRUSR | S_IWUSR)) != 0) { 220 pathbuf_destroy(pb); 221 goto done; 222 } 223 vp = nd.ni_vp; 224 pathbuf_destroy(pb); 225 226 /* 227 * Don't dump to: 228 * - non-regular files 229 * - files with links 230 * - files we don't own 231 */ 232 if (vp->v_type != VREG || 233 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 234 vattr.va_uid != kauth_cred_geteuid(cred)) { 235 error = EACCES; 236 goto out; 237 } 238 vattr_null(&vattr); 239 vattr.va_size = 0; 240 241 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 242 vattr.va_uid = security_setidcore_owner; 243 vattr.va_gid = security_setidcore_group; 244 vattr.va_mode = security_setidcore_mode; 245 } 246 247 VOP_SETATTR(vp, &vattr, cred); 248 p->p_acflag |= ACORE; 249 250 io.io_lwp = l; 251 io.io_vp = vp; 252 io.io_cred = cred; 253 io.io_offset = 0; 254 255 /* Now dump the actual core file. */ 256 error = (*p->p_execsw->es_coredump)(l, &io); 257 out: 258 VOP_UNLOCK(vp); 259 error1 = vn_close(vp, FWRITE, cred); 260 if (error == 0) 261 error = error1; 262 done: 263 if (name != NULL) 264 PNBUF_PUT(name); 265 return error; 266 } 267 268 static int 269 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 270 { 271 const char *s; 272 char *d, *end; 273 int i; 274 275 KASSERT(mutex_owned(proc_lock)); 276 277 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 278 if (*s == '%') { 279 switch (*(s + 1)) { 280 case 'n': 281 i = snprintf(d, end - d, "%s", p->p_comm); 282 break; 283 case 'p': 284 i = snprintf(d, end - d, "%d", p->p_pid); 285 break; 286 case 'u': 287 i = snprintf(d, end - d, "%.*s", 288 (int)sizeof p->p_pgrp->pg_session->s_login, 289 p->p_pgrp->pg_session->s_login); 290 break; 291 case 't': 292 i = snprintf(d, end - d, "%lld", 293 (long long)p->p_stats->p_start.tv_sec); 294 break; 295 default: 296 goto copy; 297 } 298 d += i; 299 s++; 300 } else { 301 copy: *d = *s; 302 d++; 303 } 304 if (d >= end) 305 return (ENAMETOOLONG); 306 } 307 *d = '\0'; 308 return 0; 309 } 310 311 int 312 coredump_write(struct coredump_iostate *io, enum uio_seg segflg, 313 const void *data, size_t len) 314 { 315 int error; 316 317 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 318 io->io_offset, segflg, 319 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 320 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 321 if (error) { 322 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 323 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 324 segflg == UIO_USERSPACE ? "user" : "system", 325 len, data, (long long) io->io_offset, error); 326 return (error); 327 } 328 329 io->io_offset += len; 330 return (0); 331 } 332 333 off_t 334 coredump_offset(struct coredump_iostate *io) 335 { 336 return io->io_offset; 337 } 338