kern_core.c revision 1.20
1 /* $NetBSD: kern_core.c,v 1.20 2011/09/24 22:53:50 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 1.20 2011/09/24 22:53:50 christos 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 /* 159 * On a simple filename, see if the filesystem allow us to write 160 * core dumps there. 161 */ 162 lastslash = strrchr(name, '/'); 163 if (!lastslash) { 164 vp = p->p_cwdi->cwdi_cdir; 165 if (vp->v_mount == NULL || 166 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 167 error = EPERM; 168 } 169 170 mutex_exit(p->p_lock); 171 mutex_exit(proc_lock); 172 if (error) 173 goto done; 174 175 /* 176 * On a complex filename, see if the filesystem allow us to write 177 * core dumps there. 178 * 179 * XXX: We should have an API that avoids double lookups 180 */ 181 if (lastslash) { 182 char c[2]; 183 184 if (lastslash - name >= MAXPATHLEN - 2) { 185 error = EPERM; 186 goto done; 187 } 188 189 c[0] = lastslash[1]; 190 c[1] = lastslash[2]; 191 lastslash[1] = '.'; 192 lastslash[2] = '\0'; 193 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 194 if (error) 195 goto done; 196 if (vp->v_mount == NULL || 197 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 198 error = EPERM; 199 vrele(vp); 200 if (error) 201 goto done; 202 lastslash[1] = c[0]; 203 lastslash[2] = c[1]; 204 } 205 206 pb = pathbuf_create(name); 207 if (pb == NULL) { 208 error = ENOMEM; 209 goto done; 210 } 211 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 212 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 213 S_IRUSR | S_IWUSR)) != 0) { 214 pathbuf_destroy(pb); 215 goto done; 216 } 217 vp = nd.ni_vp; 218 pathbuf_destroy(pb); 219 220 /* 221 * Don't dump to: 222 * - non-regular files 223 * - files with links 224 * - files we don't own 225 */ 226 if (vp->v_type != VREG || 227 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 228 vattr.va_uid != kauth_cred_geteuid(cred)) { 229 error = EACCES; 230 goto out; 231 } 232 vattr_null(&vattr); 233 vattr.va_size = 0; 234 235 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 236 vattr.va_uid = security_setidcore_owner; 237 vattr.va_gid = security_setidcore_group; 238 vattr.va_mode = security_setidcore_mode; 239 } 240 241 VOP_SETATTR(vp, &vattr, cred); 242 p->p_acflag |= ACORE; 243 244 io.io_lwp = l; 245 io.io_vp = vp; 246 io.io_cred = cred; 247 io.io_offset = 0; 248 249 /* Now dump the actual core file. */ 250 error = (*p->p_execsw->es_coredump)(l, &io); 251 out: 252 VOP_UNLOCK(vp); 253 error1 = vn_close(vp, FWRITE, cred); 254 if (error == 0) 255 error = error1; 256 done: 257 if (name != NULL) 258 PNBUF_PUT(name); 259 return error; 260 } 261 262 static int 263 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 264 { 265 const char *s; 266 char *d, *end; 267 int i; 268 269 KASSERT(mutex_owned(proc_lock)); 270 271 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 272 if (*s == '%') { 273 switch (*(s + 1)) { 274 case 'n': 275 i = snprintf(d, end - d, "%s", p->p_comm); 276 break; 277 case 'p': 278 i = snprintf(d, end - d, "%d", p->p_pid); 279 break; 280 case 'u': 281 i = snprintf(d, end - d, "%.*s", 282 (int)sizeof p->p_pgrp->pg_session->s_login, 283 p->p_pgrp->pg_session->s_login); 284 break; 285 case 't': 286 i = snprintf(d, end - d, "%lld", 287 (long long)p->p_stats->p_start.tv_sec); 288 break; 289 default: 290 goto copy; 291 } 292 d += i; 293 s++; 294 } else { 295 copy: *d = *s; 296 d++; 297 } 298 if (d >= end) 299 return (ENAMETOOLONG); 300 } 301 *d = '\0'; 302 return 0; 303 } 304 305 int 306 coredump_write(void *cookie, enum uio_seg segflg, const void *data, size_t len) 307 { 308 struct coredump_iostate *io = cookie; 309 int error; 310 311 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 312 io->io_offset, segflg, 313 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 314 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 315 if (error) { 316 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 317 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 318 segflg == UIO_USERSPACE ? "user" : "system", 319 len, data, (long long) io->io_offset, error); 320 return (error); 321 } 322 323 io->io_offset += len; 324 return (0); 325 } 326
Indexes created Sun Sep 21 18:09:52 GMT 2025