lib/libkvm/kvm.c

   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  * 3. All advertising materials mentioning features or use of this software
  18  *    must display the following acknowledgement:
  19  *      This product includes software developed by the University of
  20  *      California, Berkeley and its contributors.
  21  * 4. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  * @(#)kvm.c    8.2 (Berkeley) 2/13/94
  38  * $FreeBSD: src/lib/libkvm/kvm.c,v 1.12.2.3 2002/09/13 14:53:43 nectar Exp $
  39  * $DragonFly: src/lib/libkvm/kvm.c,v 1.12 2008/02/13 00:12:46 corecode Exp $
  40  */
  41
  42 #include <sys/user.h>   /* MUST BE FIRST */
  43 #include <sys/param.h>
  44 #include <sys/proc.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/stat.h>
  47 #include <sys/sysctl.h>
  48 #include <sys/linker.h>
  49
  50 #include <vm/vm.h>
  51 #include <vm/vm_param.h>
  52 #include <vm/swap_pager.h>
  53
  54 #include <machine/vmparam.h>
  55
  56 #include <ctype.h>
  57 #include <fcntl.h>
  58 #include <kvm.h>
  59 #include <limits.h>
  60 #include <nlist.h>
  61 #include <paths.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65 #include <stdarg.h>
  66 #include <unistd.h>
  67
  68 #include "kvm_private.h"
  69
  70 /* from src/lib/libc/gen/nlist.c */
  71 int __fdnlist           (int, struct nlist *);
  72
  73 char *
  74 kvm_geterr(kvm_t *kd)
  75 {
  76         return (kd->errbuf);
  77 }
  78
  79 /*
  80  * Report an error using printf style arguments.  "program" is kd->program
  81  * on hard errors, and 0 on soft errors, so that under sun error emulation,
  82  * only hard errors are printed out (otherwise, programs like gdb will
  83  * generate tons of error messages when trying to access bogus pointers).
  84  */
  85 void
  86 _kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
  87 {
  88         va_list ap;
  89
  90         va_start(ap, fmt);
  91         if (program != NULL) {
  92                 (void)fprintf(stderr, "%s: ", program);
  93                 (void)vfprintf(stderr, fmt, ap);
  94                 (void)fputc('\n', stderr);
  95         } else
  96                 (void)vsnprintf(kd->errbuf,
  97                     sizeof(kd->errbuf), (char *)fmt, ap);
  98
  99         va_end(ap);
 100 }
 101
 102 void
 103 _kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
 104 {
 105         va_list ap;
 106         int n;
 107
 108         va_start(ap, fmt);
 109         if (program != NULL) {
 110                 (void)fprintf(stderr, "%s: ", program);
 111                 (void)vfprintf(stderr, fmt, ap);
 112                 (void)fprintf(stderr, ": %s\n", strerror(errno));
 113         } else {
 114                 char *cp = kd->errbuf;
 115
 116                 (void)vsnprintf(cp, sizeof(kd->errbuf), (char *)fmt, ap);
 117                 n = strlen(cp);
 118                 (void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
 119                     strerror(errno));
 120         }
 121         va_end(ap);
 122 }
 123
 124 void *
 125 _kvm_malloc(kvm_t *kd, size_t n)
 126 {
 127         void *p;
 128
 129         if ((p = calloc(n, sizeof(char))) == NULL)
 130                 _kvm_err(kd, kd->program, "can't allocate %u bytes: %s",
 131                          n, strerror(errno));
 132         return (p);
 133 }
 134
 135 static int
 136 is_proc_mem(const char *p)
 137 {
 138         static char proc[] = "/proc/";
 139         static char mem[] = "/mem";
 140         if (strncmp(proc, p, sizeof(proc) - 1))
 141                 return 0;
 142         p += sizeof(proc) - 1;
 143         for (; p != '\0'; ++p)
 144                 if (!isdigit(*p))
 145                         break;
 146         if (!isdigit(*(p - 1)))
 147                 return 0;
 148         return !strncmp(p, mem, sizeof(mem) - 1);
 149 }
 150
 151 static kvm_t *
 152 _kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout)
 153 {
 154         struct stat st;
 155
 156         kd->vmfd = -1;
 157         kd->pmfd = -1;
 158         kd->nlfd = -1;
 159         kd->vmst = 0;
 160         kd->procbase = NULL;
 161         kd->procend = NULL;
 162         kd->argspc = 0;
 163         kd->argv = 0;
 164         kd->flags = 0;
 165
 166         if (uf == 0)
 167                 uf = getbootfile();
 168         else if (strlen(uf) >= MAXPATHLEN) {
 169                 _kvm_err(kd, kd->program, "exec file name too long");
 170                 goto failed;
 171         }
 172         if (flag & ~O_RDWR) {
 173                 _kvm_err(kd, kd->program, "bad flags arg");
 174                 goto failed;
 175         }
 176         if (mf == 0)
 177                 mf = _PATH_MEM;
 178
 179         if ((kd->pmfd = open(mf, flag, 0)) < 0) {
 180                 _kvm_syserr(kd, kd->program, "%s", mf);
 181                 goto failed;
 182         }
 183         if (fstat(kd->pmfd, &st) < 0) {
 184                 _kvm_syserr(kd, kd->program, "%s", mf);
 185                 goto failed;
 186         }
 187         if (fcntl(kd->pmfd, F_SETFD, FD_CLOEXEC) < 0) {
 188                 _kvm_syserr(kd, kd->program, "%s", mf);
 189                 goto failed;
 190         }
 191         if (S_ISCHR(st.st_mode)) {
 192                 /*
 193                  * If this is a character special device, then check that
 194                  * it's /dev/mem.  If so, open kmem too.  (Maybe we should
 195                  * make it work for either /dev/mem or /dev/kmem -- in either
 196                  * case you're working with a live kernel.)
 197                  */
 198                 if (strcmp(mf, _PATH_DEVNULL) == 0) {
 199                         kd->vmfd = open(_PATH_DEVNULL, O_RDONLY);
 200                 } else {
 201                         if ((kd->vmfd = open(_PATH_KMEM, flag)) < 0) {
 202                                 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
 203                                 goto failed;
 204                         }
 205                         if (fcntl(kd->vmfd, F_SETFD, FD_CLOEXEC) < 0) {
 206                                 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
 207                                 goto failed;
 208                         }
 209                 }
 210                 kd->flags |= KVMF_HOST;
 211         } else {
 212                 /*
 213                  * Crash dump or vkernel /proc/$pid/mem file:
 214                  * can't use kldsym, we are going to need ->nlfd
 215                  */
 216                 if ((kd->nlfd = open(uf, O_RDONLY, 0)) < 0) {
 217                         _kvm_syserr(kd, kd->program, "%s", uf);
 218                         goto failed;
 219                 }
 220                 if (fcntl(kd->nlfd, F_SETFD, FD_CLOEXEC) < 0) {
 221                         _kvm_syserr(kd, kd->program, "%s", uf);
 222                         goto failed;
 223                 }
 224                 if(is_proc_mem(mf)) {
 225                         /*
 226                          * It's /proc/$pid/mem, so we rely on the host
 227                          * kernel to do address translation for us.
 228                          */
 229                         kd->vmfd = kd->pmfd;
 230                         kd->pmfd = -1;
 231                         kd->flags |= KVMF_VKERN;
 232                 } else {
 233                         if (st.st_size <= 0) {
 234                                 errno = EINVAL;
 235                                 _kvm_syserr(kd, kd->program, "empty file");
 236                                 goto failed;
 237                         }
 238
 239                         /*
 240                          * This is a crash dump.
 241                          * Initialize the virtual address translation machinery,
 242                          * but first setup the namelist fd.
 243                          */
 244                         if (_kvm_initvtop(kd) < 0)
 245                                 goto failed;
 246                 }
 247         }
 248         return (kd);
 249 failed:
 250         /*
 251          * Copy out the error if doing sane error semantics.
 252          */
 253         if (errout != 0)
 254                 strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
 255         (void)kvm_close(kd);
 256         return (0);
 257 }
 258
 259 kvm_t *
 260 kvm_openfiles(const char *uf, const char *mf, const char *sf, int flag,
 261               char *errout)
 262 {
 263         kvm_t *kd;
 264
 265         if ((kd = malloc(sizeof(*kd))) == NULL) {
 266                 (void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
 267                 return (0);
 268         }
 269         memset(kd, 0, sizeof(*kd));
 270         kd->program = 0;
 271         return (_kvm_open(kd, uf, mf, flag, errout));
 272 }
 273
 274 kvm_t *
 275 kvm_open(const char *uf, const char *mf, const char *sf, int flag,
 276          const char *errstr)
 277 {
 278         kvm_t *kd;
 279
 280         if ((kd = malloc(sizeof(*kd))) == NULL) {
 281                 if (errstr != NULL)
 282                         (void)fprintf(stderr, "%s: %s\n",
 283                                       errstr, strerror(errno));
 284                 return (0);
 285         }
 286         memset(kd, 0, sizeof(*kd));
 287         kd->program = errstr;
 288         return (_kvm_open(kd, uf, mf, flag, NULL));
 289 }
 290
 291 int
 292 kvm_close(kvm_t *kd)
 293 {
 294         int error = 0;
 295
 296         if (kd->pmfd >= 0)
 297                 error |= close(kd->pmfd);
 298         if (kd->vmfd >= 0)
 299                 error |= close(kd->vmfd);
 300         if (kd->nlfd >= 0)
 301                 error |= close(kd->nlfd);
 302         if (kd->vmst)
 303                 _kvm_freevtop(kd);
 304         if (kd->procbase != NULL)
 305                 free(kd->procbase);
 306         if (kd->argv != 0)
 307                 free((void *)kd->argv);
 308         free((void *)kd);
 309
 310         return (0);
 311 }
 312
 313 int
 314 kvm_nlist(kvm_t *kd, struct nlist *nl)
 315 {
 316         struct nlist *p;
 317         int nvalid;
 318         struct kld_sym_lookup lookup;
 319         int error;
 320
 321         /*
 322          * If we can't use the kld symbol lookup, revert to the
 323          * slow library call.
 324          */
 325         if (!kvm_ishost(kd))
 326                 return (__fdnlist(kd->nlfd, nl));
 327
 328         /*
 329          * We can use the kld lookup syscall.  Go through each nlist entry
 330          * and look it up with a kldsym(2) syscall.
 331          */
 332         nvalid = 0;
 333         for (p = nl; p->n_name && p->n_name[0]; ++p) {
 334                 lookup.version = sizeof(lookup);
 335                 lookup.symname = p->n_name;
 336                 lookup.symvalue = 0;
 337                 lookup.symsize = 0;
 338
 339                 if (lookup.symname[0] == '_')
 340                         lookup.symname++;
 341
 342                 if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
 343                         p->n_type = N_TEXT;
 344                         p->n_other = 0;
 345                         p->n_desc = 0;
 346                         p->n_value = lookup.symvalue;
 347                         ++nvalid;
 348                         /* lookup.symsize */
 349                 }
 350         }
 351         /*
 352          * Return the number of entries that weren't found. If they exist,
 353          * also fill internal error buffer.
 354          */
 355         error = ((p - nl) - nvalid);
 356         if (error)
 357                 _kvm_syserr(kd, kd->program, "kvm_nlist");
 358         return (error);
 359 }
 360
 361 ssize_t
 362 kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
 363 {
 364         int cc;
 365         void *cp;
 366
 367         if (kvm_notrans(kd)) {
 368                 /*
 369                  * We're using /dev/kmem.  Just read straight from the
 370                  * device and let the active kernel do the address translation.
 371                  */
 372                 errno = 0;
 373                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 374                         _kvm_err(kd, 0, "invalid address (%lx)", kva);
 375                         return (-1);
 376                 }
 377
 378                 /*
 379                  * Try to pre-fault the user memory to reduce instances of
 380                  * races within the kernel.  XXX workaround for kernel bug
 381                  * where kernel does a sanity check, but user faults during
 382                  * the copy can block and race against another kernel entity
 383                  * unmapping the memory in question.
 384                  */
 385                 bzero(buf, len);
 386                 cc = read(kd->vmfd, buf, len);
 387                 if (cc < 0) {
 388                         _kvm_syserr(kd, 0, "kvm_read");
 389                         return (-1);
 390                 } else if (cc < len)
 391                         _kvm_err(kd, kd->program, "short read");
 392                 return (cc);
 393         } else {
 394                 cp = buf;
 395                 while (len > 0) {
 396                         u_long pa;
 397
 398                         cc = _kvm_kvatop(kd, kva, &pa);
 399                         if (cc == 0)
 400                                 return (-1);
 401                         if (cc > len)
 402                                 cc = len;
 403                         errno = 0;
 404                         if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
 405                                 _kvm_syserr(kd, 0, _PATH_MEM);
 406                                 break;
 407                         }
 408                         bzero(cp, cc);
 409                         cc = read(kd->pmfd, cp, cc);
 410                         if (cc < 0) {
 411                                 _kvm_syserr(kd, kd->program, "kvm_read");
 412                                 break;
 413                         }
 414                         /*
 415                          * If kvm_kvatop returns a bogus value or our core
 416                          * file is truncated, we might wind up seeking beyond
 417                          * the end of the core file in which case the read will
 418                          * return 0 (EOF).
 419                          */
 420                         if (cc == 0)
 421                                 break;
 422                         cp = (char *)cp + cc;
 423                         kva += cc;
 424                         len -= cc;
 425                 }
 426                 return ((char *)cp - (char *)buf);
 427         }
 428         /* NOTREACHED */
 429 }
 430
 431 char *
 432 kvm_readstr(kvm_t *kd, u_long kva, char *buf, size_t *lenp)
 433 {
 434         size_t len, cc, pos;
 435         char ch;
 436         int asize = -1;
 437
 438         if (buf == NULL) {
 439                 asize = len = 16;
 440                 buf = malloc(len);
 441                 if (buf == NULL) {
 442                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 443                         return NULL;
 444                 }
 445         } else {
 446                 len = *lenp;
 447         }
 448
 449         if (kvm_notrans(kd)) {
 450                 /*
 451                  * We're using /dev/kmem.  Just read straight from the
 452                  * device and let the active kernel do the address translation.
 453                  */
 454                 errno = 0;
 455                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 456                         _kvm_err(kd, 0, "invalid address (%lx)", kva);
 457                         return NULL;
 458                 }
 459
 460                 for (pos = 0, ch = -1; ch != 0; pos++) {
 461                         cc = read(kd->vmfd, &ch, 1);
 462                         if ((ssize_t)cc < 0) {
 463                                 _kvm_syserr(kd, 0, "kvm_readstr");
 464                                 return NULL;
 465                         } else if (cc < 1)
 466                                 _kvm_err(kd, kd->program, "short read");
 467                         if (pos == asize) {
 468                                 buf = realloc(buf, asize *= 2);
 469                                 if (buf == NULL) {
 470                                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 471                                         return NULL;
 472                                 }
 473                                 len = asize;
 474                         }
 475                         if (pos < len)
 476                                 buf[pos] = ch;
 477                 }
 478
 479                 if (lenp != NULL)
 480                         *lenp = pos;
 481                 if (pos > len)
 482                         return NULL;
 483                 else
 484                         return buf;
 485         } else {
 486                 size_t left = 0;
 487                 for (pos = 0, ch = -1; ch != 0; pos++, left--, kva++) {
 488                         if (left == 0) {
 489                                 u_long pa;
 490
 491                                 left = _kvm_kvatop(kd, kva, &pa);
 492                                 if (left == 0)
 493                                         return NULL;
 494                                 errno = 0;
 495                                 if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
 496                                         _kvm_syserr(kd, 0, _PATH_MEM);
 497                                         return NULL;
 498                                 }
 499                         }
 500                         cc = read(kd->pmfd, &ch, 1);
 501                         if ((ssize_t)cc < 0) {
 502                                 _kvm_syserr(kd, 0, "kvm_readstr");
 503                                 return NULL;
 504                         } else if (cc < 1)
 505                                 _kvm_err(kd, kd->program, "short read");
 506                         if (pos == asize) {
 507                                 buf = realloc(buf, asize *= 2);
 508                                 if (buf == NULL) {
 509                                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 510                                         return NULL;
 511                                 }
 512                                 len = asize;
 513                         }
 514                         if (pos < len)
 515                                 buf[pos] = ch;
 516                 }
 517
 518                 if (lenp != NULL)
 519                         *lenp = pos;
 520                 if (pos > len)
 521                         return NULL;
 522                 else
 523                         return buf;
 524         }
 525         /* NOTREACHED */
 526 }
 527
 528 ssize_t
 529 kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
 530 {
 531         int cc;
 532
 533         if (kvm_notrans(kd)) {
 534                 /*
 535                  * Just like kvm_read, only we write.
 536                  */
 537                 errno = 0;
 538                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 539                         _kvm_err(kd, 0, "invalid address (%lx)", kva);
 540                         return (-1);
 541                 }
 542                 cc = write(kd->vmfd, buf, len);
 543                 if (cc < 0) {
 544                         _kvm_syserr(kd, 0, "kvm_write");
 545                         return (-1);
 546                 } else if (cc < len)
 547                         _kvm_err(kd, kd->program, "short write");
 548                 return (cc);
 549         } else {
 550                 _kvm_err(kd, kd->program,
 551                     "kvm_write not implemented for dead kernels");
 552                 return (-1);
 553         }
 554         /* NOTREACHED */
 555 }