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 * 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 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 * 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 * 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 * 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 * 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 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->pt_map != NULL) 301 free(kd->pt_map); 302 if (kd->page_map != NULL) 303 free(kd->page_map); 304 if (kd->sparse_map != MAP_FAILED) 305 munmap(kd->sparse_map, kd->pt_sparse_size); 306 free((void *)kd); 307 308 return (error); 309 } 310 311 int 312 kvm_nlist2(kvm_t *kd, struct kvm_nlist *nl) 313 { 314 315 /* 316 * If called via the public interface, permit initialization of 317 * further virtualized modules on demand. 318 */ 319 return (_kvm_nlist(kd, nl, 1)); 320 } 321 322 int 323 kvm_nlist(kvm_t *kd, struct nlist *nl) 324 { 325 struct kvm_nlist *kl; 326 int count, i, nfail; 327 328 /* 329 * Avoid reporting truncated addresses by failing for non-native 330 * cores. 331 */ 332 if (!kvm_native(kd)) { 333 _kvm_err(kd, kd->program, "kvm_nlist of non-native vmcore"); 334 return (-1); 335 } 336 337 for (count = 0; nl[count].n_name != NULL && nl[count].n_name[0] != '\0'; 338 count++) 339 ; 340 if (count == 0) 341 return (0); 342 kl = calloc(count + 1, sizeof(*kl)); 343 for (i = 0; i < count; i++) 344 kl[i].n_name = nl[i].n_name; 345 nfail = kvm_nlist2(kd, kl); 346 for (i = 0; i < count; i++) { 347 nl[i].n_type = kl[i].n_type; 348 nl[i].n_other = 0; 349 nl[i].n_desc = 0; 350 nl[i].n_value = kl[i].n_value; 351 } 352 return (nfail); 353 } 354 355 ssize_t 356 kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len) 357 { 358 359 return (kvm_read2(kd, kva, buf, len)); 360 } 361 362 ssize_t 363 kvm_read2(kvm_t *kd, kvaddr_t kva, void *buf, size_t len) 364 { 365 int cc; 366 ssize_t cr; 367 off_t pa; 368 char *cp; 369 370 if (ISALIVE(kd)) { 371 /* 372 * We're using /dev/kmem. Just read straight from the 373 * device and let the active kernel do the address translation. 374 */ 375 errno = 0; 376 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) { 377 _kvm_err(kd, 0, "invalid address (0x%jx)", 378 (uintmax_t)kva); 379 return (-1); 380 } 381 cr = read(kd->vmfd, buf, len); 382 if (cr < 0) { 383 _kvm_syserr(kd, 0, "kvm_read"); 384 return (-1); 385 } else if (cr < (ssize_t)len) 386 _kvm_err(kd, kd->program, "short read"); 387 return (cr); 388 } 389 390 cp = buf; 391 while (len > 0) { 392 cc = kd->arch->ka_kvatop(kd, kva, &pa); 393 if (cc == 0) 394 return (-1); 395 if (cc > (ssize_t)len) 396 cc = len; 397 errno = 0; 398 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) { 399 _kvm_syserr(kd, 0, _PATH_MEM); 400 break; 401 } 402 cr = read(kd->pmfd, cp, cc); 403 if (cr < 0) { 404 _kvm_syserr(kd, kd->program, "kvm_read"); 405 break; 406 } 407 /* 408 * If ka_kvatop returns a bogus value or our core file is 409 * truncated, we might wind up seeking beyond the end of the 410 * core file in which case the read will return 0 (EOF). 411 */ 412 if (cr == 0) 413 break; 414 cp += cr; 415 kva += cr; 416 len -= cr; 417 } 418 419 return (cp - (char *)buf); 420 } 421 422 ssize_t 423 kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len) 424 { 425 int cc; 426 ssize_t cw; 427 off_t pa; 428 const char *cp; 429 430 if (!ISALIVE(kd) && !kd->writable) { 431 _kvm_err(kd, kd->program, 432 "kvm_write not implemented for dead kernels"); 433 return (-1); 434 } 435 436 if (ISALIVE(kd)) { 437 /* 438 * Just like kvm_read, only we write. 439 */ 440 errno = 0; 441 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) { 442 _kvm_err(kd, 0, "invalid address (%lx)", kva); 443 return (-1); 444 } 445 cc = write(kd->vmfd, buf, len); 446 if (cc < 0) { 447 _kvm_syserr(kd, 0, "kvm_write"); 448 return (-1); 449 } else if ((size_t)cc < len) 450 _kvm_err(kd, kd->program, "short write"); 451 return (cc); 452 } 453 454 cp = buf; 455 while (len > 0) { 456 cc = kd->arch->ka_kvatop(kd, kva, &pa); 457 if (cc == 0) 458 return (-1); 459 if (cc > (ssize_t)len) 460 cc = len; 461 errno = 0; 462 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) { 463 _kvm_syserr(kd, 0, _PATH_MEM); 464 break; 465 } 466 cw = write(kd->pmfd, cp, cc); 467 if (cw < 0) { 468 _kvm_syserr(kd, kd->program, "kvm_write"); 469 break; 470 } 471 /* 472 * If ka_kvatop returns a bogus value or our core file is 473 * truncated, we might wind up seeking beyond the end of the 474 * core file in which case the read will return 0 (EOF). 475 */ 476 if (cw == 0) 477 break; 478 cp += cw; 479 kva += cw; 480 len -= cw; 481 } 482 483 return (cp - (const char *)buf); 484 } 485 486 int 487 kvm_native(kvm_t *kd) 488 { 489 490 if (ISALIVE(kd)) 491 return (1); 492 return (kd->arch->ka_native(kd)); 493 } 494 495 int 496 kvm_walk_pages(kvm_t *kd, kvm_walk_pages_cb_t *cb, void *closure) 497 { 498 499 if (kd->arch->ka_walk_pages == NULL) 500 return (0); 501 502 return (kd->arch->ka_walk_pages(kd, cb, closure)); 503 } 504 505 kssize_t 506 kvm_kerndisp(kvm_t *kd) 507 { 508 unsigned long kernbase, rel_kernbase; 509 size_t kernbase_len = sizeof(kernbase); 510 size_t rel_kernbase_len = sizeof(rel_kernbase); 511 512 if (ISALIVE(kd)) { 513 if (sysctlbyname("kern.base_address", &kernbase, 514 &kernbase_len, NULL, 0) == -1) { 515 _kvm_syserr(kd, kd->program, 516 "failed to get kernel base address"); 517 return (0); 518 } 519 if (sysctlbyname("kern.relbase_address", &rel_kernbase, 520 &rel_kernbase_len, NULL, 0) == -1) { 521 _kvm_syserr(kd, kd->program, 522 "failed to get relocated kernel base address"); 523 return (0); 524 } 525 return (rel_kernbase - kernbase); 526 } 527 528 if (kd->arch->ka_kerndisp == NULL) 529 return (0); 530 531 return (kd->arch->ka_kerndisp(kd)); 532 } 533