1 /* $NetBSD: kern_core.c,v 1.39 2023/10/04 22:17:09 ad 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 1.39 2023/10/04 22:17:09 ad Exp $");
41
42 #ifdef _KERNEL_OPT
43 #include "opt_execfmt.h"
44 #include "opt_compat_netbsd32.h"
45 #endif
46
47 #include <sys/param.h>
48 #include <sys/vnode.h>
49 #include <sys/namei.h>
50 #include <sys/acct.h>
51 #include <sys/file.h>
52 #include <sys/stat.h>
53 #include <sys/proc.h>
54 #include <sys/exec.h>
55 #include <sys/filedesc.h>
56 #include <sys/kauth.h>
57 #include <sys/module.h>
58 #include <sys/compat_stub.h>
59 #include <sys/exec_elf.h>
60 #include <sys/resourcevar.h>
61
62 MODULE(MODULE_CLASS_MISC, coredump, NULL);
63
64 struct coredump_iostate {
65 struct lwp *io_lwp;
66 struct vnode *io_vp;
67 kauth_cred_t io_cred;
68 off_t io_offset;
69 };
70
71 static int coredump(struct lwp *, const char *);
72 static int coredump_buildname(struct proc *, char *, const char *, size_t);
73 static int coredump_write(struct coredump_iostate *, enum uio_seg segflg,
74 const void *, size_t);
75 static off_t coredump_offset(struct coredump_iostate *);
76
77 static int
coredump_modcmd(modcmd_t cmd,void * arg)78 coredump_modcmd(modcmd_t cmd, void *arg)
79 {
80
81 switch (cmd) {
82 case MODULE_CMD_INIT:
83 MODULE_HOOK_SET(coredump_hook, coredump);
84 MODULE_HOOK_SET(coredump_write_hook, coredump_write);
85 MODULE_HOOK_SET(coredump_offset_hook, coredump_offset);
86 MODULE_HOOK_SET(coredump_netbsd_hook, real_coredump_netbsd);
87 #if defined(EXEC_ELF64)
88 MODULE_HOOK_SET(coredump_elf64_hook, real_coredump_elf64);
89 #elif defined(EXEC_ELF32)
90 MODULE_HOOK_SET(coredump_elf32_hook, real_coredump_elf32);
91 #endif
92 MODULE_HOOK_SET(uvm_coredump_walkmap_hook,
93 uvm_coredump_walkmap);
94 MODULE_HOOK_SET(uvm_coredump_count_segs_hook,
95 uvm_coredump_count_segs);
96 return 0;
97 case MODULE_CMD_FINI:
98 MODULE_HOOK_UNSET(uvm_coredump_count_segs_hook);
99 MODULE_HOOK_UNSET(uvm_coredump_walkmap_hook);
100 #if defined(EXEC_ELF64)
101 MODULE_HOOK_UNSET(coredump_elf64_hook);
102 #elif defined(EXEC_ELF32)
103 MODULE_HOOK_UNSET(coredump_elf32_hook);
104 #endif
105 MODULE_HOOK_UNSET(coredump_netbsd_hook);
106 MODULE_HOOK_UNSET(coredump_offset_hook);
107 MODULE_HOOK_UNSET(coredump_write_hook);
108 MODULE_HOOK_UNSET(coredump_hook);
109 return 0;
110 default:
111 return ENOTTY;
112 }
113 }
114
115 /*
116 * Dump core, into a file named "progname.core" or "core" (depending on the
117 * value of shortcorename), unless the process was setuid/setgid.
118 */
119 static int
coredump(struct lwp * l,const char * pattern)120 coredump(struct lwp *l, const char *pattern)
121 {
122 struct vnode *vp;
123 struct proc *p;
124 struct vmspace *vm;
125 kauth_cred_t cred = NULL;
126 struct pathbuf *pb;
127 struct vattr vattr;
128 struct coredump_iostate io;
129 struct plimit *lim;
130 int error, error1;
131 char *name, *lastslash = NULL /* XXXgcc */;
132
133 name = PNBUF_GET();
134
135 p = l->l_proc;
136 vm = p->p_vmspace;
137
138 mutex_enter(&proc_lock); /* p_session */
139 mutex_enter(p->p_lock);
140
141 /*
142 * Refuse to core if the data + stack + user size is larger than
143 * the core dump limit. XXX THIS IS WRONG, because of mapped
144 * data.
145 */
146 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >=
147 p->p_rlimit[RLIMIT_CORE].rlim_cur) {
148 error = EFBIG; /* better error code? */
149 goto release;
150 }
151
152 /*
153 * It may well not be curproc, so grab a reference to its current
154 * credentials.
155 */
156 cred = kauth_cred_hold(p->p_cred);
157
158 /*
159 * Make sure the process has not set-id, to prevent data leaks,
160 * unless it was specifically requested to allow set-id coredumps.
161 */
162 if (p->p_flag & PK_SUGID) {
163 if (!security_setidcore_dump) {
164 error = EPERM;
165 goto release;
166 }
167 pattern = security_setidcore_path;
168 }
169
170 /* Lock, as p_limit and pl_corename might change. */
171 lim = p->p_limit;
172 mutex_enter(&lim->pl_lock);
173 if (pattern == NULL) {
174 pattern = lim->pl_corename;
175 }
176 error = coredump_buildname(p, name, pattern, MAXPATHLEN);
177 mutex_exit(&lim->pl_lock);
178
179 if (error)
180 goto release;
181
182 /*
183 * On a simple filename, see if the filesystem allow us to write
184 * core dumps there.
185 */
186 lastslash = strrchr(name, '/');
187 if (!lastslash) {
188 vp = p->p_cwdi->cwdi_cdir;
189 if (vp->v_mount == NULL ||
190 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0)
191 error = EPERM;
192 }
193
194 release:
195 mutex_exit(p->p_lock);
196 mutex_exit(&proc_lock);
197 if (error)
198 goto done;
199
200 /*
201 * On a complex filename, see if the filesystem allow us to write
202 * core dumps there.
203 *
204 * XXX: We should have an API that avoids double lookups
205 */
206 if (lastslash) {
207 char c[2];
208
209 if (lastslash - name >= MAXPATHLEN - 2) {
210 error = EPERM;
211 goto done;
212 }
213
214 c[0] = lastslash[1];
215 c[1] = lastslash[2];
216 lastslash[1] = '.';
217 lastslash[2] = '\0';
218 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp);
219 if (error)
220 goto done;
221 if (vp->v_mount == NULL ||
222 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0)
223 error = EPERM;
224 vrele(vp);
225 if (error)
226 goto done;
227 lastslash[1] = c[0];
228 lastslash[2] = c[1];
229 }
230
231 pb = pathbuf_create(name);
232 if (pb == NULL) {
233 error = ENOMEM;
234 goto done;
235 }
236 error = vn_open(NULL, pb, 0, O_CREAT | O_NOFOLLOW | FWRITE,
237 S_IRUSR | S_IWUSR, &vp, NULL, NULL);
238 if (error != 0) {
239 pathbuf_destroy(pb);
240 goto done;
241 }
242 pathbuf_destroy(pb);
243
244 /*
245 * Don't dump to:
246 * - non-regular files
247 * - files with links
248 * - files we don't own
249 */
250 if (vp->v_type != VREG ||
251 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 ||
252 vattr.va_uid != kauth_cred_geteuid(cred)) {
253 error = EACCES;
254 goto out;
255 }
256 vattr_null(&vattr);
257 vattr.va_size = 0;
258
259 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) {
260 vattr.va_uid = security_setidcore_owner;
261 vattr.va_gid = security_setidcore_group;
262 vattr.va_mode = security_setidcore_mode;
263 }
264
265 VOP_SETATTR(vp, &vattr, cred);
266 p->p_acflag |= ACORE;
267
268 io.io_lwp = l;
269 io.io_vp = vp;
270 io.io_cred = cred;
271 io.io_offset = 0;
272
273 /* Now dump the actual core file. */
274 error = (*p->p_execsw->es_coredump)(l, &io);
275 out:
276 VOP_UNLOCK(vp);
277 error1 = vn_close(vp, FWRITE, cred);
278 if (error == 0)
279 error = error1;
280 done:
281 if (cred != NULL)
282 kauth_cred_free(cred);
283 if (name != NULL)
284 PNBUF_PUT(name);
285 return error;
286 }
287
288 static int
coredump_buildname(struct proc * p,char * dst,const char * src,size_t len)289 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len)
290 {
291 const char *s;
292 char *d, *end;
293 int i;
294
295 KASSERT(mutex_owned(&proc_lock));
296
297 for (s = src, d = dst, end = d + len; *s != '\0'; s++) {
298 if (*s == '%') {
299 switch (*(s + 1)) {
300 case 'n':
301 i = snprintf(d, end - d, "%s", p->p_comm);
302 break;
303 case 'p':
304 i = snprintf(d, end - d, "%d", p->p_pid);
305 break;
306 case 'u':
307 i = snprintf(d, end - d, "%.*s",
308 (int)sizeof p->p_pgrp->pg_session->s_login,
309 p->p_pgrp->pg_session->s_login);
310 break;
311 case 't':
312 i = snprintf(d, end - d, "%lld",
313 (long long)p->p_stats->p_start.tv_sec);
314 break;
315 default:
316 goto copy;
317 }
318 d += i;
319 s++;
320 } else {
321 copy: *d = *s;
322 d++;
323 }
324 if (d >= end)
325 return (ENAMETOOLONG);
326 }
327 *d = '\0';
328 return 0;
329 }
330
331 static int
coredump_write(struct coredump_iostate * io,enum uio_seg segflg,const void * data,size_t len)332 coredump_write(struct coredump_iostate *io, enum uio_seg segflg,
333 const void *data, size_t len)
334 {
335 int error;
336
337 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len,
338 io->io_offset, segflg,
339 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL,
340 segflg == UIO_USERSPACE ? io->io_lwp : NULL);
341 if (error) {
342 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n",
343 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm,
344 segflg == UIO_USERSPACE ? "user" : "system",
345 len, data, (long long) io->io_offset, error);
346 return (error);
347 }
348
349 io->io_offset += len;
350 return (0);
351 }
352
353 static off_t
coredump_offset(struct coredump_iostate * io)354 coredump_offset(struct coredump_iostate *io)
355 {
356 return io->io_offset;
357 }
358