1 /* $NetBSD: kern_core.c,v 1.17 2010/11/19 06:44:42 dholland 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 1.17 2010/11/19 06:44:42 dholland 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; 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 * The core dump will go in the current working directory. Make 137 * sure that the directory is still there and that the mount flags 138 * allow us to write core dumps there. 139 * 140 * XXX: this is partially bogus, it should be checking the directory 141 * into which the file is actually written - which probably needs 142 * a flag on namei() 143 */ 144 vp = p->p_cwdi->cwdi_cdir; 145 if (vp->v_mount == NULL || 146 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) { 147 error = EPERM; 148 mutex_exit(p->p_lock); 149 mutex_exit(proc_lock); 150 goto done; 151 } 152 153 /* 154 * Make sure the process has not set-id, to prevent data leaks, 155 * unless it was specifically requested to allow set-id coredumps. 156 */ 157 if (p->p_flag & PK_SUGID) { 158 if (!security_setidcore_dump) { 159 error = EPERM; 160 mutex_exit(p->p_lock); 161 mutex_exit(proc_lock); 162 goto done; 163 } 164 pattern = security_setidcore_path; 165 } 166 167 /* It is (just) possible for p_limit and pl_corename to change */ 168 lim = p->p_limit; 169 mutex_enter(&lim->pl_lock); 170 if (pattern == NULL) 171 pattern = lim->pl_corename; 172 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 173 mutex_exit(&lim->pl_lock); 174 mutex_exit(p->p_lock); 175 mutex_exit(proc_lock); 176 if (error) 177 goto done; 178 179 pb = pathbuf_create(name); 180 if (pb == NULL) { 181 error = ENOMEM; 182 goto done; 183 } 184 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 185 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 186 S_IRUSR | S_IWUSR)) != 0) { 187 pathbuf_destroy(pb); 188 goto done; 189 } 190 vp = nd.ni_vp; 191 pathbuf_destroy(pb); 192 193 /* Don't dump to non-regular files or files with links. */ 194 if (vp->v_type != VREG || 195 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1) { 196 error = EINVAL; 197 goto out; 198 } 199 vattr_null(&vattr); 200 vattr.va_size = 0; 201 202 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 203 vattr.va_uid = security_setidcore_owner; 204 vattr.va_gid = security_setidcore_group; 205 vattr.va_mode = security_setidcore_mode; 206 } 207 208 VOP_SETATTR(vp, &vattr, cred); 209 p->p_acflag |= ACORE; 210 211 io.io_lwp = l; 212 io.io_vp = vp; 213 io.io_cred = cred; 214 io.io_offset = 0; 215 216 /* Now dump the actual core file. */ 217 error = (*p->p_execsw->es_coredump)(l, &io); 218 out: 219 VOP_UNLOCK(vp); 220 error1 = vn_close(vp, FWRITE, cred); 221 if (error == 0) 222 error = error1; 223 done: 224 if (name != NULL) 225 PNBUF_PUT(name); 226 return error; 227 } 228 229 static int 230 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 231 { 232 const char *s; 233 char *d, *end; 234 int i; 235 236 KASSERT(mutex_owned(proc_lock)); 237 238 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 239 if (*s == '%') { 240 switch (*(s + 1)) { 241 case 'n': 242 i = snprintf(d, end - d, "%s", p->p_comm); 243 break; 244 case 'p': 245 i = snprintf(d, end - d, "%d", p->p_pid); 246 break; 247 case 'u': 248 i = snprintf(d, end - d, "%.*s", 249 (int)sizeof p->p_pgrp->pg_session->s_login, 250 p->p_pgrp->pg_session->s_login); 251 break; 252 case 't': 253 i = snprintf(d, end - d, "%lld", 254 (long long)p->p_stats->p_start.tv_sec); 255 break; 256 default: 257 goto copy; 258 } 259 d += i; 260 s++; 261 } else { 262 copy: *d = *s; 263 d++; 264 } 265 if (d >= end) 266 return (ENAMETOOLONG); 267 } 268 *d = '\0'; 269 return 0; 270 } 271 272 int 273 coredump_write(void *cookie, enum uio_seg segflg, const void *data, size_t len) 274 { 275 struct coredump_iostate *io = cookie; 276 int error; 277 278 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 279 io->io_offset, segflg, 280 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 281 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 282 if (error) { 283 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 284 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 285 segflg == UIO_USERSPACE ? "user" : "system", 286 len, data, (long long) io->io_offset, error); 287 return (error); 288 } 289 290 io->io_offset += len; 291 return (0); 292 } 293