1 /* $NetBSD: kern_core.c,v 1.27 2019/11/10 14:20:50 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 1.27 2019/11/10 14:20:50 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 67 static int 68 coredump_modcmd(modcmd_t cmd, void *arg) 69 { 70 71 switch (cmd) { 72 case MODULE_CMD_INIT: 73 MODULE_HOOK_SET(coredump_hook, "coredump", coredump); 74 return 0; 75 case MODULE_CMD_FINI: 76 /* 77 * In theory we don't need to UNSET this, as the various 78 * exec formats depend on this module. If this module has 79 * no references, and so can be unloaded, no user programs 80 * can be running and so nothing can call *coredump_vec. 81 */ 82 83 MODULE_HOOK_UNSET(coredump_hook); 84 return 0; 85 default: 86 return ENOTTY; 87 } 88 } 89 90 /* 91 * Dump core, into a file named "progname.core" or "core" (depending on the 92 * value of shortcorename), unless the process was setuid/setgid. 93 */ 94 static int 95 coredump(struct lwp *l, const char *pattern) 96 { 97 struct vnode *vp; 98 struct proc *p; 99 struct vmspace *vm; 100 kauth_cred_t cred; 101 struct pathbuf *pb; 102 struct nameidata nd; 103 struct vattr vattr; 104 struct coredump_iostate io; 105 struct plimit *lim; 106 int error, error1; 107 char *name, *lastslash; 108 109 name = PNBUF_GET(); 110 111 p = l->l_proc; 112 vm = p->p_vmspace; 113 114 mutex_enter(proc_lock); /* p_session */ 115 mutex_enter(p->p_lock); 116 117 /* 118 * Refuse to core if the data + stack + user size is larger than 119 * the core dump limit. XXX THIS IS WRONG, because of mapped 120 * data. 121 */ 122 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >= 123 p->p_rlimit[RLIMIT_CORE].rlim_cur) { 124 error = EFBIG; /* better error code? */ 125 mutex_exit(p->p_lock); 126 mutex_exit(proc_lock); 127 goto done; 128 } 129 130 /* 131 * It may well not be curproc, so grab a reference to its current 132 * credentials. 133 */ 134 kauth_cred_hold(p->p_cred); 135 cred = p->p_cred; 136 137 /* 138 * Make sure the process has not set-id, to prevent data leaks, 139 * unless it was specifically requested to allow set-id coredumps. 140 */ 141 if (p->p_flag & PK_SUGID) { 142 if (!security_setidcore_dump) { 143 error = EPERM; 144 mutex_exit(p->p_lock); 145 mutex_exit(proc_lock); 146 goto done; 147 } 148 pattern = security_setidcore_path; 149 } 150 151 /* Lock, as p_limit and pl_corename might change. */ 152 lim = p->p_limit; 153 mutex_enter(&lim->pl_lock); 154 if (pattern == NULL) { 155 pattern = lim->pl_corename; 156 } 157 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 158 mutex_exit(&lim->pl_lock); 159 160 if (error) { 161 mutex_exit(p->p_lock); 162 mutex_exit(proc_lock); 163 goto done; 164 } 165 166 /* 167 * On a simple filename, see if the filesystem allow us to write 168 * core dumps there. 169 */ 170 lastslash = strrchr(name, '/'); 171 if (!lastslash) { 172 vp = p->p_cwdi->cwdi_cdir; 173 if (vp->v_mount == NULL || 174 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 175 error = EPERM; 176 } 177 178 mutex_exit(p->p_lock); 179 mutex_exit(proc_lock); 180 if (error) 181 goto done; 182 183 /* 184 * On a complex filename, see if the filesystem allow us to write 185 * core dumps there. 186 * 187 * XXX: We should have an API that avoids double lookups 188 */ 189 if (lastslash) { 190 char c[2]; 191 192 if (lastslash - name >= MAXPATHLEN - 2) { 193 error = EPERM; 194 goto done; 195 } 196 197 c[0] = lastslash[1]; 198 c[1] = lastslash[2]; 199 lastslash[1] = '.'; 200 lastslash[2] = '\0'; 201 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 202 if (error) 203 goto done; 204 if (vp->v_mount == NULL || 205 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 206 error = EPERM; 207 vrele(vp); 208 if (error) 209 goto done; 210 lastslash[1] = c[0]; 211 lastslash[2] = c[1]; 212 } 213 214 pb = pathbuf_create(name); 215 if (pb == NULL) { 216 error = ENOMEM; 217 goto done; 218 } 219 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 220 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 221 S_IRUSR | S_IWUSR)) != 0) { 222 pathbuf_destroy(pb); 223 goto done; 224 } 225 vp = nd.ni_vp; 226 pathbuf_destroy(pb); 227 228 /* 229 * Don't dump to: 230 * - non-regular files 231 * - files with links 232 * - files we don't own 233 */ 234 if (vp->v_type != VREG || 235 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 236 vattr.va_uid != kauth_cred_geteuid(cred)) { 237 error = EACCES; 238 goto out; 239 } 240 vattr_null(&vattr); 241 vattr.va_size = 0; 242 243 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 244 vattr.va_uid = security_setidcore_owner; 245 vattr.va_gid = security_setidcore_group; 246 vattr.va_mode = security_setidcore_mode; 247 } 248 249 VOP_SETATTR(vp, &vattr, cred); 250 p->p_acflag |= ACORE; 251 252 io.io_lwp = l; 253 io.io_vp = vp; 254 io.io_cred = cred; 255 io.io_offset = 0; 256 257 /* Now dump the actual core file. */ 258 error = (*p->p_execsw->es_coredump)(l, &io); 259 out: 260 VOP_UNLOCK(vp); 261 error1 = vn_close(vp, FWRITE, cred); 262 if (error == 0) 263 error = error1; 264 done: 265 if (name != NULL) 266 PNBUF_PUT(name); 267 return error; 268 } 269 270 static int 271 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 272 { 273 const char *s; 274 char *d, *end; 275 int i; 276 277 KASSERT(mutex_owned(proc_lock)); 278 279 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 280 if (*s == '%') { 281 switch (*(s + 1)) { 282 case 'n': 283 i = snprintf(d, end - d, "%s", p->p_comm); 284 break; 285 case 'p': 286 i = snprintf(d, end - d, "%d", p->p_pid); 287 break; 288 case 'u': 289 i = snprintf(d, end - d, "%.*s", 290 (int)sizeof p->p_pgrp->pg_session->s_login, 291 p->p_pgrp->pg_session->s_login); 292 break; 293 case 't': 294 i = snprintf(d, end - d, "%lld", 295 (long long)p->p_stats->p_start.tv_sec); 296 break; 297 default: 298 goto copy; 299 } 300 d += i; 301 s++; 302 } else { 303 copy: *d = *s; 304 d++; 305 } 306 if (d >= end) 307 return (ENAMETOOLONG); 308 } 309 *d = '\0'; 310 return 0; 311 } 312 313 int 314 coredump_write(struct coredump_iostate *io, enum uio_seg segflg, 315 const void *data, size_t len) 316 { 317 int error; 318 319 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 320 io->io_offset, segflg, 321 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 322 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 323 if (error) { 324 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 325 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 326 segflg == UIO_USERSPACE ? "user" : "system", 327 len, data, (long long) io->io_offset, error); 328 return (error); 329 } 330 331 io->io_offset += len; 332 return (0); 333 } 334 335 off_t 336 coredump_offset(struct coredump_iostate *io) 337 { 338 return io->io_offset; 339 } 340