kvm.c revision 316070
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 316070 2017-03-28 05:57:20Z ngie $"); 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 (NULL); 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 (NULL); 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 (NULL); 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 == NULL) { 266 errno = EINVAL; 267 return (-1); 268 } 269 if (kd->pmfd >= 0) 270 error |= close(kd->pmfd); 271 if (kd->vmfd >= 0) 272 error |= close(kd->vmfd); 273 if (kd->nlfd >= 0) 274 error |= close(kd->nlfd); 275 if (kd->vmst) 276 _kvm_freevtop(kd); 277 if (kd->procbase != 0) 278 free((void *)kd->procbase); 279 if (kd->argbuf != 0) 280 free((void *) kd->argbuf); 281 if (kd->argspc != 0) 282 free((void *) kd->argspc); 283 if (kd->argv != 0) 284 free((void *)kd->argv); 285 free((void *)kd); 286 287 return (error); 288} 289 290/* 291 * Walk the list of unresolved symbols, generate a new list and prefix the 292 * symbol names, try again, and merge back what we could resolve. 293 */ 294static int 295kvm_fdnlist_prefix(kvm_t *kd, struct nlist *nl, int missing, const char *prefix, 296 uintptr_t (*validate_fn)(kvm_t *, uintptr_t)) 297{ 298 struct nlist *n, *np, *p; 299 char *cp, *ce; 300 const char *ccp; 301 size_t len; 302 int slen, unresolved; 303 304 /* 305 * Calculate the space we need to malloc for nlist and names. 306 * We are going to store the name twice for later lookups: once 307 * with the prefix and once the unmodified name delmited by \0. 308 */ 309 len = 0; 310 unresolved = 0; 311 for (p = nl; p->n_name && p->n_name[0]; ++p) { 312 if (p->n_type != N_UNDF) 313 continue; 314 len += sizeof(struct nlist) + strlen(prefix) + 315 2 * (strlen(p->n_name) + 1); 316 unresolved++; 317 } 318 if (unresolved == 0) 319 return (unresolved); 320 /* Add space for the terminating nlist entry. */ 321 len += sizeof(struct nlist); 322 unresolved++; 323 324 /* Alloc one chunk for (nlist, [names]) and setup pointers. */ 325 n = np = malloc(len); 326 bzero(n, len); 327 if (n == NULL) 328 return (missing); 329 cp = ce = (char *)np; 330 cp += unresolved * sizeof(struct nlist); 331 ce += len; 332 333 /* Generate shortened nlist with special prefix. */ 334 unresolved = 0; 335 for (p = nl; p->n_name && p->n_name[0]; ++p) { 336 if (p->n_type != N_UNDF) 337 continue; 338 bcopy(p, np, sizeof(struct nlist)); 339 /* Save the new\0orig. name so we can later match it again. */ 340 slen = snprintf(cp, ce - cp, "%s%s%c%s", prefix, 341 (prefix[0] != '\0' && p->n_name[0] == '_') ? 342 (p->n_name + 1) : p->n_name, '\0', p->n_name); 343 if (slen < 0 || slen >= ce - cp) 344 continue; 345 np->n_name = cp; 346 cp += slen + 1; 347 np++; 348 unresolved++; 349 } 350 351 /* Do lookup on the reduced list. */ 352 np = n; 353 unresolved = __fdnlist(kd->nlfd, np); 354 355 /* Check if we could resolve further symbols and update the list. */ 356 if (unresolved >= 0 && unresolved < missing) { 357 /* Find the first freshly resolved entry. */ 358 for (; np->n_name && np->n_name[0]; np++) 359 if (np->n_type != N_UNDF) 360 break; 361 /* 362 * The lists are both in the same order, 363 * so we can walk them in parallel. 364 */ 365 for (p = nl; np->n_name && np->n_name[0] && 366 p->n_name && p->n_name[0]; ++p) { 367 if (p->n_type != N_UNDF) 368 continue; 369 /* Skip expanded name and compare to orig. one. */ 370 ccp = np->n_name + strlen(np->n_name) + 1; 371 if (strcmp(ccp, p->n_name) != 0) 372 continue; 373 /* Update nlist with new, translated results. */ 374 p->n_type = np->n_type; 375 p->n_other = np->n_other; 376 p->n_desc = np->n_desc; 377 if (validate_fn) 378 p->n_value = (*validate_fn)(kd, np->n_value); 379 else 380 p->n_value = np->n_value; 381 missing--; 382 /* Find next freshly resolved entry. */ 383 for (np++; np->n_name && np->n_name[0]; np++) 384 if (np->n_type != N_UNDF) 385 break; 386 } 387 } 388 /* We could assert missing = unresolved here. */ 389 390 free(n); 391 return (unresolved); 392} 393 394int 395_kvm_nlist(kvm_t *kd, struct nlist *nl, int initialize) 396{ 397 struct nlist *p; 398 int nvalid; 399 struct kld_sym_lookup lookup; 400 int error; 401 const char *prefix = ""; 402 char symname[1024]; /* XXX-BZ symbol name length limit? */ 403 int tried_vnet, tried_dpcpu; 404 405 /* 406 * If we can't use the kld symbol lookup, revert to the 407 * slow library call. 408 */ 409 if (!ISALIVE(kd)) { 410 error = __fdnlist(kd->nlfd, nl); 411 if (error <= 0) /* Hard error or success. */ 412 return (error); 413 414 if (_kvm_vnet_initialized(kd, initialize)) 415 error = kvm_fdnlist_prefix(kd, nl, error, 416 VNET_SYMPREFIX, _kvm_vnet_validaddr); 417 418 if (error > 0 && _kvm_dpcpu_initialized(kd, initialize)) 419 error = kvm_fdnlist_prefix(kd, nl, error, 420 DPCPU_SYMPREFIX, _kvm_dpcpu_validaddr); 421 422 return (error); 423 } 424 425 /* 426 * We can use the kld lookup syscall. Go through each nlist entry 427 * and look it up with a kldsym(2) syscall. 428 */ 429 nvalid = 0; 430 tried_vnet = 0; 431 tried_dpcpu = 0; 432again: 433 for (p = nl; p->n_name && p->n_name[0]; ++p) { 434 if (p->n_type != N_UNDF) 435 continue; 436 437 lookup.version = sizeof(lookup); 438 lookup.symvalue = 0; 439 lookup.symsize = 0; 440 441 error = snprintf(symname, sizeof(symname), "%s%s", prefix, 442 (prefix[0] != '\0' && p->n_name[0] == '_') ? 443 (p->n_name + 1) : p->n_name); 444 if (error < 0 || error >= (int)sizeof(symname)) 445 continue; 446 lookup.symname = symname; 447 if (lookup.symname[0] == '_') 448 lookup.symname++; 449 450 if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) { 451 p->n_type = N_TEXT; 452 p->n_other = 0; 453 p->n_desc = 0; 454 if (_kvm_vnet_initialized(kd, initialize) && 455 strcmp(prefix, VNET_SYMPREFIX) == 0) 456 p->n_value = 457 _kvm_vnet_validaddr(kd, lookup.symvalue); 458 else if (_kvm_dpcpu_initialized(kd, initialize) && 459 strcmp(prefix, DPCPU_SYMPREFIX) == 0) 460 p->n_value = 461 _kvm_dpcpu_validaddr(kd, lookup.symvalue); 462 else 463 p->n_value = lookup.symvalue; 464 ++nvalid; 465 /* lookup.symsize */ 466 } 467 } 468 469 /* 470 * Check the number of entries that weren't found. If they exist, 471 * try again with a prefix for virtualized or DPCPU symbol names. 472 */ 473 error = ((p - nl) - nvalid); 474 if (error && _kvm_vnet_initialized(kd, initialize) && !tried_vnet) { 475 tried_vnet = 1; 476 prefix = VNET_SYMPREFIX; 477 goto again; 478 } 479 if (error && _kvm_dpcpu_initialized(kd, initialize) && !tried_dpcpu) { 480 tried_dpcpu = 1; 481 prefix = DPCPU_SYMPREFIX; 482 goto again; 483 } 484 485 /* 486 * Return the number of entries that weren't found. If they exist, 487 * also fill internal error buffer. 488 */ 489 error = ((p - nl) - nvalid); 490 if (error) 491 _kvm_syserr(kd, kd->program, "kvm_nlist"); 492 return (error); 493} 494 495int 496kvm_nlist(kvm_t *kd, struct nlist *nl) 497{ 498 499 /* 500 * If called via the public interface, permit intialization of 501 * further virtualized modules on demand. 502 */ 503 return (_kvm_nlist(kd, nl, 1)); 504} 505 506ssize_t 507kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len) 508{ 509 int cc; 510 ssize_t cr; 511 off_t pa; 512 char *cp; 513 514 if (ISALIVE(kd)) { 515 /* 516 * We're using /dev/kmem. Just read straight from the 517 * device and let the active kernel do the address translation. 518 */ 519 errno = 0; 520 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) { 521 _kvm_err(kd, 0, "invalid address (%lx)", kva); 522 return (-1); 523 } 524 cr = read(kd->vmfd, buf, len); 525 if (cr < 0) { 526 _kvm_syserr(kd, 0, "kvm_read"); 527 return (-1); 528 } else if (cr < (ssize_t)len) 529 _kvm_err(kd, kd->program, "short read"); 530 return (cr); 531 } 532 533 cp = buf; 534 while (len > 0) { 535 cc = _kvm_kvatop(kd, kva, &pa); 536 if (cc == 0) 537 return (-1); 538 if (cc > (ssize_t)len) 539 cc = len; 540 errno = 0; 541 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) { 542 _kvm_syserr(kd, 0, _PATH_MEM); 543 break; 544 } 545 cr = read(kd->pmfd, cp, cc); 546 if (cr < 0) { 547 _kvm_syserr(kd, kd->program, "kvm_read"); 548 break; 549 } 550 /* 551 * If kvm_kvatop returns a bogus value or our core file is 552 * truncated, we might wind up seeking beyond the end of the 553 * core file in which case the read will return 0 (EOF). 554 */ 555 if (cr == 0) 556 break; 557 cp += cr; 558 kva += cr; 559 len -= cr; 560 } 561 562 return (cp - (char *)buf); 563} 564 565ssize_t 566kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len) 567{ 568 int cc; 569 ssize_t cw; 570 off_t pa; 571 const char *cp; 572 573 if (!ISALIVE(kd) && !kd->writable) { 574 _kvm_err(kd, kd->program, 575 "kvm_write not implemented for dead kernels"); 576 return (-1); 577 } 578 579 if (ISALIVE(kd)) { 580 /* 581 * Just like kvm_read, only we write. 582 */ 583 errno = 0; 584 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) { 585 _kvm_err(kd, 0, "invalid address (%lx)", kva); 586 return (-1); 587 } 588 cc = write(kd->vmfd, buf, len); 589 if (cc < 0) { 590 _kvm_syserr(kd, 0, "kvm_write"); 591 return (-1); 592 } else if ((size_t)cc < len) 593 _kvm_err(kd, kd->program, "short write"); 594 return (cc); 595 } 596 597 cp = buf; 598 while (len > 0) { 599 cc = _kvm_kvatop(kd, kva, &pa); 600 if (cc == 0) 601 return (-1); 602 if (cc > (ssize_t)len) 603 cc = len; 604 errno = 0; 605 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) { 606 _kvm_syserr(kd, 0, _PATH_MEM); 607 break; 608 } 609 cw = write(kd->pmfd, cp, cc); 610 if (cw < 0) { 611 _kvm_syserr(kd, kd->program, "kvm_write"); 612 break; 613 } 614 /* 615 * If ka_kvatop returns a bogus value or our core file is 616 * truncated, we might wind up seeking beyond the end of the 617 * core file in which case the read will return 0 (EOF). 618 */ 619 if (cw == 0) 620 break; 621 cp += cw; 622 kva += cw; 623 len -= cw; 624 } 625 626 return (cp - (char *)buf); 627} 628