1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1989, 1992, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software developed by the Computer Systems
8 * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
9 * BG 91-66 and contributed to Berkeley.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38 __SCCSID("@(#)kvm.c 8.2 (Berkeley) 2/13/94");
39
40 #include <sys/param.h>
41 #include <sys/fnv_hash.h>
42
43 #define _WANT_VNET
44
45 #include <sys/user.h>
46 #include <sys/linker.h>
47 #include <sys/pcpu.h>
48 #include <sys/stat.h>
49 #include <sys/sysctl.h>
50 #include <sys/mman.h>
51
52 #include <stdbool.h>
53 #include <net/vnet.h>
54
55 #include <fcntl.h>
56 #include <kvm.h>
57 #include <limits.h>
58 #include <paths.h>
59 #include <stdint.h>
60 #include <stdio.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include <unistd.h>
64
65 #include "kvm_private.h"
66
67 SET_DECLARE(kvm_arch, struct kvm_arch);
68
69 static char _kd_is_null[] = "";
70
71 char *
kvm_geterr(kvm_t * kd)72 kvm_geterr(kvm_t *kd)
73 {
74
75 if (kd == NULL)
76 return (_kd_is_null);
77 return (kd->errbuf);
78 }
79
80 static int
_kvm_read_kernel_ehdr(kvm_t * kd)81 _kvm_read_kernel_ehdr(kvm_t *kd)
82 {
83 Elf *elf;
84
85 if (elf_version(EV_CURRENT) == EV_NONE) {
86 _kvm_err(kd, kd->program, "Unsupported libelf");
87 return (-1);
88 }
89 elf = elf_begin(kd->nlfd, ELF_C_READ, NULL);
90 if (elf == NULL) {
91 _kvm_err(kd, kd->program, "%s", elf_errmsg(0));
92 return (-1);
93 }
94 if (elf_kind(elf) != ELF_K_ELF) {
95 _kvm_err(kd, kd->program, "kernel is not an ELF file");
96 return (-1);
97 }
98 if (gelf_getehdr(elf, &kd->nlehdr) == NULL) {
99 _kvm_err(kd, kd->program, "%s", elf_errmsg(0));
100 elf_end(elf);
101 return (-1);
102 }
103 elf_end(elf);
104
105 switch (kd->nlehdr.e_ident[EI_DATA]) {
106 case ELFDATA2LSB:
107 case ELFDATA2MSB:
108 return (0);
109 default:
110 _kvm_err(kd, kd->program,
111 "unsupported ELF data encoding for kernel");
112 return (-1);
113 }
114 }
115
116 static kvm_t *
_kvm_open(kvm_t * kd,const char * uf,const char * mf,int flag,char * errout)117 _kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout)
118 {
119 struct kvm_arch **parch;
120 struct stat st;
121
122 kd->vmfd = -1;
123 kd->pmfd = -1;
124 kd->nlfd = -1;
125 kd->vmst = NULL;
126 kd->procbase = NULL;
127 kd->argspc = NULL;
128 kd->argv = NULL;
129
130 if (uf == NULL)
131 uf = getbootfile();
132 else if (strlen(uf) >= MAXPATHLEN) {
133 _kvm_err(kd, kd->program, "exec file name too long");
134 goto failed;
135 }
136 if (flag & ~O_RDWR) {
137 _kvm_err(kd, kd->program, "bad flags arg");
138 goto failed;
139 }
140 if (mf == NULL)
141 mf = _PATH_MEM;
142
143 if ((kd->pmfd = open(mf, flag | O_CLOEXEC, 0)) < 0) {
144 _kvm_syserr(kd, kd->program, "%s", mf);
145 goto failed;
146 }
147 if (fstat(kd->pmfd, &st) < 0) {
148 _kvm_syserr(kd, kd->program, "%s", mf);
149 goto failed;
150 }
151 if (S_ISREG(st.st_mode) && st.st_size <= 0) {
152 errno = EINVAL;
153 _kvm_syserr(kd, kd->program, "empty file");
154 goto failed;
155 }
156 if (S_ISCHR(st.st_mode)) {
157 /*
158 * If this is a character special device, then check that
159 * it's /dev/mem. If so, open kmem too. (Maybe we should
160 * make it work for either /dev/mem or /dev/kmem -- in either
161 * case you're working with a live kernel.)
162 */
163 if (strcmp(mf, _PATH_DEVNULL) == 0) {
164 kd->vmfd = open(_PATH_DEVNULL, O_RDONLY | O_CLOEXEC);
165 return (kd);
166 } else if (strcmp(mf, _PATH_MEM) == 0) {
167 if ((kd->vmfd = open(_PATH_KMEM, flag | O_CLOEXEC)) <
168 0) {
169 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
170 goto failed;
171 }
172 return (kd);
173 }
174 }
175
176 /*
177 * This is either a crash dump or a remote live system with its physical
178 * memory fully accessible via a special device.
179 * Open the namelist fd and determine the architecture.
180 */
181 if ((kd->nlfd = open(uf, O_RDONLY | O_CLOEXEC, 0)) < 0) {
182 _kvm_syserr(kd, kd->program, "%s", uf);
183 goto failed;
184 }
185 if (_kvm_read_kernel_ehdr(kd) < 0)
186 goto failed;
187 if (strncmp(mf, _PATH_FWMEM, strlen(_PATH_FWMEM)) == 0 ||
188 strncmp(mf, _PATH_DEVVMM, strlen(_PATH_DEVVMM)) == 0) {
189 kd->rawdump = 1;
190 kd->writable = 1;
191 }
192 SET_FOREACH(parch, kvm_arch) {
193 if ((*parch)->ka_probe(kd)) {
194 kd->arch = *parch;
195 break;
196 }
197 }
198 if (kd->arch == NULL) {
199 _kvm_err(kd, kd->program, "unsupported architecture");
200 goto failed;
201 }
202
203 /*
204 * Non-native kernels require a symbol resolver.
205 */
206 if (!kd->arch->ka_native(kd) && kd->resolve_symbol == NULL) {
207 _kvm_err(kd, kd->program,
208 "non-native kernel requires a symbol resolver");
209 goto failed;
210 }
211
212 /*
213 * Initialize the virtual address translation machinery.
214 */
215 if (kd->arch->ka_initvtop(kd) < 0)
216 goto failed;
217 return (kd);
218 failed:
219 /*
220 * Copy out the error if doing sane error semantics.
221 */
222 if (errout != NULL)
223 strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
224 (void)kvm_close(kd);
225 return (NULL);
226 }
227
228 kvm_t *
kvm_openfiles(const char * uf,const char * mf,const char * sf __unused,int flag,char * errout)229 kvm_openfiles(const char *uf, const char *mf, const char *sf __unused, int flag,
230 char *errout)
231 {
232 kvm_t *kd;
233
234 if ((kd = calloc(1, sizeof(*kd))) == NULL) {
235 if (errout != NULL)
236 (void)strlcpy(errout, strerror(errno),
237 _POSIX2_LINE_MAX);
238 return (NULL);
239 }
240 return (_kvm_open(kd, uf, mf, flag, errout));
241 }
242
243 kvm_t *
kvm_open(const char * uf,const char * mf,const char * sf __unused,int flag,const char * errstr)244 kvm_open(const char *uf, const char *mf, const char *sf __unused, int flag,
245 const char *errstr)
246 {
247 kvm_t *kd;
248
249 if ((kd = calloc(1, sizeof(*kd))) == NULL) {
250 if (errstr != NULL)
251 (void)fprintf(stderr, "%s: %s\n",
252 errstr, strerror(errno));
253 return (NULL);
254 }
255 kd->program = errstr;
256 return (_kvm_open(kd, uf, mf, flag, NULL));
257 }
258
259 kvm_t *
kvm_open2(const char * uf,const char * mf,int flag,char * errout,int (* resolver)(const char *,kvaddr_t *))260 kvm_open2(const char *uf, const char *mf, int flag, char *errout,
261 int (*resolver)(const char *, kvaddr_t *))
262 {
263 kvm_t *kd;
264
265 if ((kd = calloc(1, sizeof(*kd))) == NULL) {
266 if (errout != NULL)
267 (void)strlcpy(errout, strerror(errno),
268 _POSIX2_LINE_MAX);
269 return (NULL);
270 }
271 kd->resolve_symbol = resolver;
272 return (_kvm_open(kd, uf, mf, flag, errout));
273 }
274
275 int
kvm_close(kvm_t * kd)276 kvm_close(kvm_t *kd)
277 {
278 int error = 0;
279
280 if (kd == NULL) {
281 errno = EINVAL;
282 return (-1);
283 }
284 if (kd->vmst != NULL)
285 kd->arch->ka_freevtop(kd);
286 if (kd->pmfd >= 0)
287 error |= close(kd->pmfd);
288 if (kd->vmfd >= 0)
289 error |= close(kd->vmfd);
290 if (kd->nlfd >= 0)
291 error |= close(kd->nlfd);
292 if (kd->procbase != 0)
293 free((void *)kd->procbase);
294 if (kd->argbuf != 0)
295 free((void *) kd->argbuf);
296 if (kd->argspc != 0)
297 free((void *) kd->argspc);
298 if (kd->argv != 0)
299 free((void *)kd->argv);
300 if (kd->dpcpu_initialized != 0)
301 free(kd->dpcpu_off);
302 if (kd->pt_map != NULL)
303 free(kd->pt_map);
304 if (kd->page_map != NULL)
305 free(kd->page_map);
306 if (kd->sparse_map != MAP_FAILED)
307 munmap(kd->sparse_map, kd->pt_sparse_size);
308 free((void *)kd);
309
310 return (error);
311 }
312
313 int
kvm_nlist2(kvm_t * kd,struct kvm_nlist * nl)314 kvm_nlist2(kvm_t *kd, struct kvm_nlist *nl)
315 {
316
317 /*
318 * If called via the public interface, permit initialization of
319 * further virtualized modules on demand.
320 */
321 return (_kvm_nlist(kd, nl, 1));
322 }
323
324 int
kvm_nlist(kvm_t * kd,struct nlist * nl)325 kvm_nlist(kvm_t *kd, struct nlist *nl)
326 {
327 struct kvm_nlist *kl;
328 int count, i, nfail;
329
330 /*
331 * Avoid reporting truncated addresses by failing for non-native
332 * cores.
333 */
334 if (!kvm_native(kd)) {
335 _kvm_err(kd, kd->program, "kvm_nlist of non-native vmcore");
336 return (-1);
337 }
338
339 for (count = 0; nl[count].n_name != NULL && nl[count].n_name[0] != '\0';
340 count++)
341 ;
342 if (count == 0)
343 return (0);
344 kl = calloc(count + 1, sizeof(*kl));
345 if (kl == NULL) {
346 _kvm_err(kd, kd->program, "cannot allocate memory");
347 return (-1);
348 }
349 for (i = 0; i < count; i++)
350 kl[i].n_name = nl[i].n_name;
351 nfail = kvm_nlist2(kd, kl);
352 for (i = 0; i < count; i++) {
353 nl[i].n_type = kl[i].n_type;
354 nl[i].n_other = 0;
355 nl[i].n_desc = 0;
356 nl[i].n_value = kl[i].n_value;
357 }
358 free(kl);
359 return (nfail);
360 }
361
362 ssize_t
kvm_read(kvm_t * kd,u_long kva,void * buf,size_t len)363 kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
364 {
365
366 return (kvm_read2(kd, kva, buf, len));
367 }
368
369 ssize_t
kvm_read2(kvm_t * kd,kvaddr_t kva,void * buf,size_t len)370 kvm_read2(kvm_t *kd, kvaddr_t kva, void *buf, size_t len)
371 {
372 int cc;
373 ssize_t cr;
374 off_t pa;
375 char *cp;
376
377 if (ISALIVE(kd)) {
378 /*
379 * We're using /dev/kmem. Just read straight from the
380 * device and let the active kernel do the address translation.
381 */
382 errno = 0;
383 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
384 _kvm_err(kd, 0, "invalid address (0x%jx)",
385 (uintmax_t)kva);
386 return (-1);
387 }
388 cr = read(kd->vmfd, buf, len);
389 if (cr < 0) {
390 _kvm_syserr(kd, 0, "kvm_read");
391 return (-1);
392 } else if (cr < (ssize_t)len)
393 _kvm_err(kd, kd->program, "short read");
394 return (cr);
395 }
396
397 cp = buf;
398 while (len > 0) {
399 cc = kd->arch->ka_kvatop(kd, kva, &pa);
400 if (cc == 0)
401 return (-1);
402 if (cc > (ssize_t)len)
403 cc = len;
404 errno = 0;
405 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
406 _kvm_syserr(kd, 0, _PATH_MEM);
407 break;
408 }
409 cr = read(kd->pmfd, cp, cc);
410 if (cr < 0) {
411 _kvm_syserr(kd, kd->program, "kvm_read");
412 break;
413 }
414 /*
415 * If ka_kvatop returns a bogus value or our core file is
416 * truncated, we might wind up seeking beyond the end of the
417 * core file in which case the read will return 0 (EOF).
418 */
419 if (cr == 0)
420 break;
421 cp += cr;
422 kva += cr;
423 len -= cr;
424 }
425
426 return (cp - (char *)buf);
427 }
428
429 ssize_t
kvm_write(kvm_t * kd,u_long kva,const void * buf,size_t len)430 kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
431 {
432 int cc;
433 ssize_t cw;
434 off_t pa;
435 const char *cp;
436
437 if (!ISALIVE(kd) && !kd->writable) {
438 _kvm_err(kd, kd->program,
439 "kvm_write not implemented for dead kernels");
440 return (-1);
441 }
442
443 if (ISALIVE(kd)) {
444 /*
445 * Just like kvm_read, only we write.
446 */
447 errno = 0;
448 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
449 _kvm_err(kd, 0, "invalid address (%lx)", kva);
450 return (-1);
451 }
452 cc = write(kd->vmfd, buf, len);
453 if (cc < 0) {
454 _kvm_syserr(kd, 0, "kvm_write");
455 return (-1);
456 } else if ((size_t)cc < len)
457 _kvm_err(kd, kd->program, "short write");
458 return (cc);
459 }
460
461 cp = buf;
462 while (len > 0) {
463 cc = kd->arch->ka_kvatop(kd, kva, &pa);
464 if (cc == 0)
465 return (-1);
466 if (cc > (ssize_t)len)
467 cc = len;
468 errno = 0;
469 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
470 _kvm_syserr(kd, 0, _PATH_MEM);
471 break;
472 }
473 cw = write(kd->pmfd, cp, cc);
474 if (cw < 0) {
475 _kvm_syserr(kd, kd->program, "kvm_write");
476 break;
477 }
478 /*
479 * If ka_kvatop returns a bogus value or our core file is
480 * truncated, we might wind up seeking beyond the end of the
481 * core file in which case the read will return 0 (EOF).
482 */
483 if (cw == 0)
484 break;
485 cp += cw;
486 kva += cw;
487 len -= cw;
488 }
489
490 return (cp - (const char *)buf);
491 }
492
493 int
kvm_native(kvm_t * kd)494 kvm_native(kvm_t *kd)
495 {
496
497 if (ISALIVE(kd))
498 return (1);
499 return (kd->arch->ka_native(kd));
500 }
501
502 int
kvm_walk_pages(kvm_t * kd,kvm_walk_pages_cb_t * cb,void * closure)503 kvm_walk_pages(kvm_t *kd, kvm_walk_pages_cb_t *cb, void *closure)
504 {
505
506 if (kd->arch->ka_walk_pages == NULL)
507 return (0);
508
509 return (kd->arch->ka_walk_pages(kd, cb, closure));
510 }
511
512 kssize_t
kvm_kerndisp(kvm_t * kd)513 kvm_kerndisp(kvm_t *kd)
514 {
515 unsigned long kernbase, rel_kernbase;
516 size_t kernbase_len = sizeof(kernbase);
517 size_t rel_kernbase_len = sizeof(rel_kernbase);
518
519 if (ISALIVE(kd)) {
520 if (sysctlbyname("kern.base_address", &kernbase,
521 &kernbase_len, NULL, 0) == -1) {
522 _kvm_syserr(kd, kd->program,
523 "failed to get kernel base address");
524 return (0);
525 }
526 if (sysctlbyname("kern.relbase_address", &rel_kernbase,
527 &rel_kernbase_len, NULL, 0) == -1) {
528 _kvm_syserr(kd, kd->program,
529 "failed to get relocated kernel base address");
530 return (0);
531 }
532 return (rel_kernbase - kernbase);
533 }
534
535 if (kd->arch->ka_kerndisp == NULL)
536 return (0);
537
538 return (kd->arch->ka_kerndisp(kd));
539 }
540