kvm.c revision 312382
1/*- 2 * Copyright (c) 1989, 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software developed by the Computer Systems 6 * Engineering group at Lawrence Berkeley Laboratory under DARPA contract 7 * BG 91-66 and contributed to Berkeley. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#include <sys/cdefs.h> 35__FBSDID("$FreeBSD: stable/10/lib/libkvm/kvm.c 312382 2017-01-18 14:14:00Z avg $"); 36 37#if defined(LIBC_SCCS) && !defined(lint) 38#if 0 39static char sccsid[] = "@(#)kvm.c 8.2 (Berkeley) 2/13/94"; 40#endif 41#endif /* LIBC_SCCS and not lint */ 42 43#include <sys/param.h> 44 45#define _WANT_VNET 46 47#include <sys/user.h> 48#include <sys/proc.h> 49#include <sys/ioctl.h> 50#include <sys/stat.h> 51#include <sys/sysctl.h> 52#include <sys/linker.h> 53#include <sys/pcpu.h> 54 55#include <net/vnet.h> 56 57#include <vm/vm.h> 58#include <vm/vm_param.h> 59 60#include <machine/vmparam.h> 61 62#include <ctype.h> 63#include <fcntl.h> 64#include <kvm.h> 65#include <limits.h> 66#include <nlist.h> 67#include <paths.h> 68#include <stdio.h> 69#include <stdlib.h> 70#include <string.h> 71#include <strings.h> 72#include <unistd.h> 73 74#include "kvm_private.h" 75 76/* from src/lib/libc/gen/nlist.c */ 77int __fdnlist(int, struct nlist *); 78 79char * 80kvm_geterr(kvm_t *kd) 81{ 82 return (kd->errbuf); 83} 84 85#include <stdarg.h> 86 87/* 88 * Report an error using printf style arguments. "program" is kd->program 89 * on hard errors, and 0 on soft errors, so that under sun error emulation, 90 * only hard errors are printed out (otherwise, programs like gdb will 91 * generate tons of error messages when trying to access bogus pointers). 92 */ 93void 94_kvm_err(kvm_t *kd, const char *program, const char *fmt, ...) 95{ 96 va_list ap; 97 98 va_start(ap, fmt); 99 if (program != NULL) { 100 (void)fprintf(stderr, "%s: ", program); 101 (void)vfprintf(stderr, fmt, ap); 102 (void)fputc('\n', stderr); 103 } else 104 (void)vsnprintf(kd->errbuf, 105 sizeof(kd->errbuf), fmt, ap); 106 107 va_end(ap); 108} 109 110void 111_kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...) 112{ 113 va_list ap; 114 int n; 115 116 va_start(ap, fmt); 117 if (program != NULL) { 118 (void)fprintf(stderr, "%s: ", program); 119 (void)vfprintf(stderr, fmt, ap); 120 (void)fprintf(stderr, ": %s\n", strerror(errno)); 121 } else { 122 char *cp = kd->errbuf; 123 124 (void)vsnprintf(cp, sizeof(kd->errbuf), fmt, ap); 125 n = strlen(cp); 126 (void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s", 127 strerror(errno)); 128 } 129 va_end(ap); 130} 131 132void * 133_kvm_malloc(kvm_t *kd, size_t n) 134{ 135 void *p; 136 137 if ((p = calloc(n, sizeof(char))) == NULL) 138 _kvm_err(kd, kd->program, "can't allocate %zu bytes: %s", 139 n, strerror(errno)); 140 return (p); 141} 142 143static kvm_t * 144_kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout) 145{ 146 struct stat st; 147 148 kd->vmfd = -1; 149 kd->pmfd = -1; 150 kd->nlfd = -1; 151 kd->vmst = 0; 152 kd->procbase = 0; 153 kd->argspc = 0; 154 kd->argv = 0; 155 156 if (uf == 0) 157 uf = getbootfile(); 158 else if (strlen(uf) >= MAXPATHLEN) { 159 _kvm_err(kd, kd->program, "exec file name too long"); 160 goto failed; 161 } 162 if (flag & ~O_RDWR) { 163 _kvm_err(kd, kd->program, "bad flags arg"); 164 goto failed; 165 } 166 if (mf == 0) 167 mf = _PATH_MEM; 168 169 if ((kd->pmfd = open(mf, flag | O_CLOEXEC, 0)) < 0) { 170 _kvm_syserr(kd, kd->program, "%s", mf); 171 goto failed; 172 } 173 if (fstat(kd->pmfd, &st) < 0) { 174 _kvm_syserr(kd, kd->program, "%s", mf); 175 goto failed; 176 } 177 if (S_ISREG(st.st_mode) && st.st_size <= 0) { 178 errno = EINVAL; 179 _kvm_syserr(kd, kd->program, "empty file"); 180 goto failed; 181 } 182 if (S_ISCHR(st.st_mode)) { 183 /* 184 * If this is a character special device, then check that 185 * it's /dev/mem. If so, open kmem too. (Maybe we should 186 * make it work for either /dev/mem or /dev/kmem -- in either 187 * case you're working with a live kernel.) 188 */ 189 if (strcmp(mf, _PATH_DEVNULL) == 0) { 190 kd->vmfd = open(_PATH_DEVNULL, O_RDONLY | O_CLOEXEC); 191 return (kd); 192 } else if (strcmp(mf, _PATH_MEM) == 0) { 193 if ((kd->vmfd = open(_PATH_KMEM, flag | O_CLOEXEC)) < 194 0) { 195 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM); 196 goto failed; 197 } 198 return (kd); 199 } 200 } 201 202 /* 203 * This is either a crash dump or a remote live system with its physical 204 * memory fully accessible via a special device. 205 * Initialize the virtual address translation machinery, 206 * but first setup the namelist fd. 207 */ 208 if ((kd->nlfd = open(uf, O_RDONLY | O_CLOEXEC, 0)) < 0) { 209 _kvm_syserr(kd, kd->program, "%s", uf); 210 goto failed; 211 } 212 if (strncmp(mf, _PATH_FWMEM, strlen(_PATH_FWMEM)) == 0 || 213 strncmp(mf, _PATH_DEVVMM, strlen(_PATH_DEVVMM)) == 0) { 214 kd->rawdump = 1; 215 kd->writable = 1; 216 } 217 if (_kvm_initvtop(kd) < 0) 218 goto failed; 219 return (kd); 220failed: 221 /* 222 * Copy out the error if doing sane error semantics. 223 */ 224 if (errout != 0) 225 strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX); 226 (void)kvm_close(kd); 227 return (0); 228} 229 230kvm_t * 231kvm_openfiles(const char *uf, const char *mf, const char *sf __unused, int flag, 232 char *errout) 233{ 234 kvm_t *kd; 235 236 if ((kd = calloc(1, sizeof(*kd))) == NULL) { 237 (void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX); 238 return (0); 239 } 240 kd->program = 0; 241 return (_kvm_open(kd, uf, mf, flag, errout)); 242} 243 244kvm_t * 245kvm_open(const char *uf, const char *mf, const char *sf __unused, int flag, 246 const char *errstr) 247{ 248 kvm_t *kd; 249 250 if ((kd = calloc(1, sizeof(*kd))) == NULL) { 251 if (errstr != NULL) 252 (void)fprintf(stderr, "%s: %s\n", 253 errstr, strerror(errno)); 254 return (0); 255 } 256 kd->program = errstr; 257 return (_kvm_open(kd, uf, mf, flag, NULL)); 258} 259 260int 261kvm_close(kvm_t *kd) 262{ 263 int error = 0; 264 265 if (kd->pmfd >= 0) 266 error |= close(kd->pmfd); 267 if (kd->vmfd >= 0) 268 error |= close(kd->vmfd); 269 if (kd->nlfd >= 0) 270 error |= close(kd->nlfd); 271 if (kd->vmst) 272 _kvm_freevtop(kd); 273 if (kd->procbase != 0) 274 free((void *)kd->procbase); 275 if (kd->argbuf != 0) 276 free((void *) kd->argbuf); 277 if (kd->argspc != 0) 278 free((void *) kd->argspc); 279 if (kd->argv != 0) 280 free((void *)kd->argv); 281 free((void *)kd); 282 283 return (0); 284} 285 286/* 287 * Walk the list of unresolved symbols, generate a new list and prefix the 288 * symbol names, try again, and merge back what we could resolve. 289 */ 290static int 291kvm_fdnlist_prefix(kvm_t *kd, struct nlist *nl, int missing, const char *prefix, 292 uintptr_t (*validate_fn)(kvm_t *, uintptr_t)) 293{ 294 struct nlist *n, *np, *p; 295 char *cp, *ce; 296 const char *ccp; 297 size_t len; 298 int slen, unresolved; 299 300 /* 301 * Calculate the space we need to malloc for nlist and names. 302 * We are going to store the name twice for later lookups: once 303 * with the prefix and once the unmodified name delmited by \0. 304 */ 305 len = 0; 306 unresolved = 0; 307 for (p = nl; p->n_name && p->n_name[0]; ++p) { 308 if (p->n_type != N_UNDF) 309 continue; 310 len += sizeof(struct nlist) + strlen(prefix) + 311 2 * (strlen(p->n_name) + 1); 312 unresolved++; 313 } 314 if (unresolved == 0) 315 return (unresolved); 316 /* Add space for the terminating nlist entry. */ 317 len += sizeof(struct nlist); 318 unresolved++; 319 320 /* Alloc one chunk for (nlist, [names]) and setup pointers. */ 321 n = np = malloc(len); 322 bzero(n, len); 323 if (n == NULL) 324 return (missing); 325 cp = ce = (char *)np; 326 cp += unresolved * sizeof(struct nlist); 327 ce += len; 328 329 /* Generate shortened nlist with special prefix. */ 330 unresolved = 0; 331 for (p = nl; p->n_name && p->n_name[0]; ++p) { 332 if (p->n_type != N_UNDF) 333 continue; 334 bcopy(p, np, sizeof(struct nlist)); 335 /* Save the new\0orig. name so we can later match it again. */ 336 slen = snprintf(cp, ce - cp, "%s%s%c%s", prefix, 337 (prefix[0] != '\0' && p->n_name[0] == '_') ? 338 (p->n_name + 1) : p->n_name, '\0', p->n_name); 339 if (slen < 0 || slen >= ce - cp) 340 continue; 341 np->n_name = cp; 342 cp += slen + 1; 343 np++; 344 unresolved++; 345 } 346 347 /* Do lookup on the reduced list. */ 348 np = n; 349 unresolved = __fdnlist(kd->nlfd, np); 350 351 /* Check if we could resolve further symbols and update the list. */ 352 if (unresolved >= 0 && unresolved < missing) { 353 /* Find the first freshly resolved entry. */ 354 for (; np->n_name && np->n_name[0]; np++) 355 if (np->n_type != N_UNDF) 356 break; 357 /* 358 * The lists are both in the same order, 359 * so we can walk them in parallel. 360 */ 361 for (p = nl; np->n_name && np->n_name[0] && 362 p->n_name && p->n_name[0]; ++p) { 363 if (p->n_type != N_UNDF) 364 continue; 365 /* Skip expanded name and compare to orig. one. */ 366 ccp = np->n_name + strlen(np->n_name) + 1; 367 if (strcmp(ccp, p->n_name) != 0) 368 continue; 369 /* Update nlist with new, translated results. */ 370 p->n_type = np->n_type; 371 p->n_other = np->n_other; 372 p->n_desc = np->n_desc; 373 if (validate_fn) 374 p->n_value = (*validate_fn)(kd, np->n_value); 375 else 376 p->n_value = np->n_value; 377 missing--; 378 /* Find next freshly resolved entry. */ 379 for (np++; np->n_name && np->n_name[0]; np++) 380 if (np->n_type != N_UNDF) 381 break; 382 } 383 } 384 /* We could assert missing = unresolved here. */ 385 386 free(n); 387 return (unresolved); 388} 389 390int 391_kvm_nlist(kvm_t *kd, struct nlist *nl, int initialize) 392{ 393 struct nlist *p; 394 int nvalid; 395 struct kld_sym_lookup lookup; 396 int error; 397 const char *prefix = ""; 398 char symname[1024]; /* XXX-BZ symbol name length limit? */ 399 int tried_vnet, tried_dpcpu; 400 401 /* 402 * If we can't use the kld symbol lookup, revert to the 403 * slow library call. 404 */ 405 if (!ISALIVE(kd)) { 406 error = __fdnlist(kd->nlfd, nl); 407 if (error <= 0) /* Hard error or success. */ 408 return (error); 409 410 if (_kvm_vnet_initialized(kd, initialize)) 411 error = kvm_fdnlist_prefix(kd, nl, error, 412 VNET_SYMPREFIX, _kvm_vnet_validaddr); 413 414 if (error > 0 && _kvm_dpcpu_initialized(kd, initialize)) 415 error = kvm_fdnlist_prefix(kd, nl, error, 416 DPCPU_SYMPREFIX, _kvm_dpcpu_validaddr); 417 418 return (error); 419 } 420 421 /* 422 * We can use the kld lookup syscall. Go through each nlist entry 423 * and look it up with a kldsym(2) syscall. 424 */ 425 nvalid = 0; 426 tried_vnet = 0; 427 tried_dpcpu = 0; 428again: 429 for (p = nl; p->n_name && p->n_name[0]; ++p) { 430 if (p->n_type != N_UNDF) 431 continue; 432 433 lookup.version = sizeof(lookup); 434 lookup.symvalue = 0; 435 lookup.symsize = 0; 436 437 error = snprintf(symname, sizeof(symname), "%s%s", prefix, 438 (prefix[0] != '\0' && p->n_name[0] == '_') ? 439 (p->n_name + 1) : p->n_name); 440 if (error < 0 || error >= (int)sizeof(symname)) 441 continue; 442 lookup.symname = symname; 443 if (lookup.symname[0] == '_') 444 lookup.symname++; 445 446 if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) { 447 p->n_type = N_TEXT; 448 p->n_other = 0; 449 p->n_desc = 0; 450 if (_kvm_vnet_initialized(kd, initialize) && 451 strcmp(prefix, VNET_SYMPREFIX) == 0) 452 p->n_value = 453 _kvm_vnet_validaddr(kd, lookup.symvalue); 454 else if (_kvm_dpcpu_initialized(kd, initialize) && 455 strcmp(prefix, DPCPU_SYMPREFIX) == 0) 456 p->n_value = 457 _kvm_dpcpu_validaddr(kd, lookup.symvalue); 458 else 459 p->n_value = lookup.symvalue; 460 ++nvalid; 461 /* lookup.symsize */ 462 } 463 } 464 465 /* 466 * Check the number of entries that weren't found. If they exist, 467 * try again with a prefix for virtualized or DPCPU symbol names. 468 */ 469 error = ((p - nl) - nvalid); 470 if (error && _kvm_vnet_initialized(kd, initialize) && !tried_vnet) { 471 tried_vnet = 1; 472 prefix = VNET_SYMPREFIX; 473 goto again; 474 } 475 if (error && _kvm_dpcpu_initialized(kd, initialize) && !tried_dpcpu) { 476 tried_dpcpu = 1; 477 prefix = DPCPU_SYMPREFIX; 478 goto again; 479 } 480 481 /* 482 * Return the number of entries that weren't found. If they exist, 483 * also fill internal error buffer. 484 */ 485 error = ((p - nl) - nvalid); 486 if (error) 487 _kvm_syserr(kd, kd->program, "kvm_nlist"); 488 return (error); 489} 490 491int 492kvm_nlist(kvm_t *kd, struct nlist *nl) 493{ 494 495 /* 496 * If called via the public interface, permit intialization of 497 * further virtualized modules on demand. 498 */ 499 return (_kvm_nlist(kd, nl, 1)); 500} 501 502ssize_t 503kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len) 504{ 505 int cc; 506 ssize_t cr; 507 off_t pa; 508 char *cp; 509 510 if (ISALIVE(kd)) { 511 /* 512 * We're using /dev/kmem. Just read straight from the 513 * device and let the active kernel do the address translation. 514 */ 515 errno = 0; 516 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) { 517 _kvm_err(kd, 0, "invalid address (%lx)", kva); 518 return (-1); 519 } 520 cr = read(kd->vmfd, buf, len); 521 if (cr < 0) { 522 _kvm_syserr(kd, 0, "kvm_read"); 523 return (-1); 524 } else if (cr < (ssize_t)len) 525 _kvm_err(kd, kd->program, "short read"); 526 return (cr); 527 } 528 529 cp = buf; 530 while (len > 0) { 531 cc = _kvm_kvatop(kd, kva, &pa); 532 if (cc == 0) 533 return (-1); 534 if (cc > (ssize_t)len) 535 cc = len; 536 errno = 0; 537 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) { 538 _kvm_syserr(kd, 0, _PATH_MEM); 539 break; 540 } 541 cr = read(kd->pmfd, cp, cc); 542 if (cr < 0) { 543 _kvm_syserr(kd, kd->program, "kvm_read"); 544 break; 545 } 546 /* 547 * If kvm_kvatop returns a bogus value or our core file is 548 * truncated, we might wind up seeking beyond the end of the 549 * core file in which case the read will return 0 (EOF). 550 */ 551 if (cr == 0) 552 break; 553 cp += cr; 554 kva += cr; 555 len -= cr; 556 } 557 558 return (cp - (char *)buf); 559} 560 561ssize_t 562kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len) 563{ 564 int cc; 565 ssize_t cw; 566 off_t pa; 567 const char *cp; 568 569 if (!ISALIVE(kd) && !kd->writable) { 570 _kvm_err(kd, kd->program, 571 "kvm_write not implemented for dead kernels"); 572 return (-1); 573 } 574 575 if (ISALIVE(kd)) { 576 /* 577 * Just like kvm_read, only we write. 578 */ 579 errno = 0; 580 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) { 581 _kvm_err(kd, 0, "invalid address (%lx)", kva); 582 return (-1); 583 } 584 cc = write(kd->vmfd, buf, len); 585 if (cc < 0) { 586 _kvm_syserr(kd, 0, "kvm_write"); 587 return (-1); 588 } else if ((size_t)cc < len) 589 _kvm_err(kd, kd->program, "short write"); 590 return (cc); 591 } 592 593 cp = buf; 594 while (len > 0) { 595 cc = _kvm_kvatop(kd, kva, &pa); 596 if (cc == 0) 597 return (-1); 598 if (cc > (ssize_t)len) 599 cc = len; 600 errno = 0; 601 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) { 602 _kvm_syserr(kd, 0, _PATH_MEM); 603 break; 604 } 605 cw = write(kd->pmfd, cp, cc); 606 if (cw < 0) { 607 _kvm_syserr(kd, kd->program, "kvm_write"); 608 break; 609 } 610 /* 611 * If ka_kvatop returns a bogus value or our core file is 612 * truncated, we might wind up seeking beyond the end of the 613 * core file in which case the read will return 0 (EOF). 614 */ 615 if (cw == 0) 616 break; 617 cp += cw; 618 kva += cw; 619 len -= cw; 620 } 621 622 return (cp - (char *)buf); 623} 624