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 kvm_t *
 136 _kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout)
 137 {
 138         struct stat st;
 139
 140         kd->vmfd = -1;
 141         kd->pmfd = -1;
 142         kd->nlfd = -1;
 143         kd->vmst = 0;
 144         kd->procbase = NULL;
 145         kd->procend = NULL;
 146         kd->argspc = 0;
 147         kd->argv = 0;
 148
 149         if (uf == 0)
 150                 uf = getbootfile();
 151         else if (strlen(uf) >= MAXPATHLEN) {
 152                 _kvm_err(kd, kd->program, "exec file name too long");
 153                 goto failed;
 154         }
 155         if (flag & ~O_RDWR) {
 156                 _kvm_err(kd, kd->program, "bad flags arg");
 157                 goto failed;
 158         }
 159         if (mf == 0)
 160                 mf = _PATH_MEM;
 161
 162         if ((kd->pmfd = open(mf, flag, 0)) < 0) {
 163                 _kvm_syserr(kd, kd->program, "%s", mf);
 164                 goto failed;
 165         }
 166         if (fstat(kd->pmfd, &st) < 0) {
 167                 _kvm_syserr(kd, kd->program, "%s", mf);
 168                 goto failed;
 169         }
 170         if (S_ISREG(st.st_mode) && st.st_size <= 0) {
 171                 errno = EINVAL;
 172                 _kvm_syserr(kd, kd->program, "empty file");
 173                 goto failed;
 174         }
 175         if (fcntl(kd->pmfd, F_SETFD, FD_CLOEXEC) < 0) {
 176                 _kvm_syserr(kd, kd->program, "%s", mf);
 177                 goto failed;
 178         }
 179         if (S_ISCHR(st.st_mode)) {
 180                 /*
 181                  * If this is a character special device, then check that
 182                  * it's /dev/mem.  If so, open kmem too.  (Maybe we should
 183                  * make it work for either /dev/mem or /dev/kmem -- in either
 184                  * case you're working with a live kernel.)
 185                  */
 186                 if (strcmp(mf, _PATH_DEVNULL) == 0) {
 187                         kd->vmfd = open(_PATH_DEVNULL, O_RDONLY);
 188                 } else {
 189                         if ((kd->vmfd = open(_PATH_KMEM, flag)) < 0) {
 190                                 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
 191                                 goto failed;
 192                         }
 193                         if (fcntl(kd->vmfd, F_SETFD, FD_CLOEXEC) < 0) {
 194                                 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
 195                                 goto failed;
 196                         }
 197                 }
 198         } else {
 199                 /*
 200                  * This is a crash dump.
 201                  * Initialize the virtual address translation machinery,
 202                  * but first setup the namelist fd.
 203                  */
 204                 if ((kd->nlfd = open(uf, O_RDONLY, 0)) < 0) {
 205                         _kvm_syserr(kd, kd->program, "%s", uf);
 206                         goto failed;
 207                 }
 208                 if (fcntl(kd->nlfd, F_SETFD, FD_CLOEXEC) < 0) {
 209                         _kvm_syserr(kd, kd->program, "%s", uf);
 210                         goto failed;
 211                 }
 212                 if (_kvm_initvtop(kd) < 0)
 213                         goto failed;
 214         }
 215         return (kd);
 216 failed:
 217         /*
 218          * Copy out the error if doing sane error semantics.
 219          */
 220         if (errout != 0)
 221                 strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
 222         (void)kvm_close(kd);
 223         return (0);
 224 }
 225
 226 kvm_t *
 227 kvm_openfiles(const char *uf, const char *mf, const char *sf, int flag,
 228               char *errout)
 229 {
 230         kvm_t *kd;
 231
 232         if ((kd = malloc(sizeof(*kd))) == NULL) {
 233                 (void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
 234                 return (0);
 235         }
 236         memset(kd, 0, sizeof(*kd));
 237         kd->program = 0;
 238         return (_kvm_open(kd, uf, mf, flag, errout));
 239 }
 240
 241 kvm_t *
 242 kvm_open(const char *uf, const char *mf, const char *sf, int flag,
 243          const char *errstr)
 244 {
 245         kvm_t *kd;
 246
 247         if ((kd = malloc(sizeof(*kd))) == NULL) {
 248                 if (errstr != NULL)
 249                         (void)fprintf(stderr, "%s: %s\n",
 250                                       errstr, strerror(errno));
 251                 return (0);
 252         }
 253         memset(kd, 0, sizeof(*kd));
 254         kd->program = errstr;
 255         return (_kvm_open(kd, uf, mf, flag, NULL));
 256 }
 257
 258 int
 259 kvm_close(kvm_t *kd)
 260 {
 261         int error = 0;
 262
 263         if (kd->pmfd >= 0)
 264                 error |= close(kd->pmfd);
 265         if (kd->vmfd >= 0)
 266                 error |= close(kd->vmfd);
 267         if (kd->nlfd >= 0)
 268                 error |= close(kd->nlfd);
 269         if (kd->vmst)
 270                 _kvm_freevtop(kd);
 271         if (kd->procbase != NULL)
 272                 free(kd->procbase);
 273         if (kd->argv != 0)
 274                 free((void *)kd->argv);
 275         free((void *)kd);
 276
 277         return (0);
 278 }
 279
 280 int
 281 kvm_nlist(kvm_t *kd, struct nlist *nl)
 282 {
 283         struct nlist *p;
 284         int nvalid;
 285         struct kld_sym_lookup lookup;
 286         int error;
 287
 288         /*
 289          * If we can't use the kld symbol lookup, revert to the
 290          * slow library call.
 291          */
 292         if (!ISALIVE(kd))
 293                 return (__fdnlist(kd->nlfd, nl));
 294
 295         /*
 296          * We can use the kld lookup syscall.  Go through each nlist entry
 297          * and look it up with a kldsym(2) syscall.
 298          */
 299         nvalid = 0;
 300         for (p = nl; p->n_name && p->n_name[0]; ++p) {
 301                 lookup.version = sizeof(lookup);
 302                 lookup.symname = p->n_name;
 303                 lookup.symvalue = 0;
 304                 lookup.symsize = 0;
 305
 306                 if (lookup.symname[0] == '_')
 307                         lookup.symname++;
 308
 309                 if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
 310                         p->n_type = N_TEXT;
 311                         p->n_other = 0;
 312                         p->n_desc = 0;
 313                         p->n_value = lookup.symvalue;
 314                         ++nvalid;
 315                         /* lookup.symsize */
 316                 }
 317         }
 318         /*
 319          * Return the number of entries that weren't found. If they exist,
 320          * also fill internal error buffer.
 321          */
 322         error = ((p - nl) - nvalid);
 323         if (error)
 324                 _kvm_syserr(kd, kd->program, "kvm_nlist");
 325         return (error);
 326 }
 327
 328 ssize_t
 329 kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
 330 {
 331         int cc;
 332         void *cp;
 333
 334         if (ISALIVE(kd)) {
 335                 /*
 336                  * We're using /dev/kmem.  Just read straight from the
 337                  * device and let the active kernel do the address translation.
 338                  */
 339                 errno = 0;
 340                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 341                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 342                         return (-1);
 343                 }
 344
 345                 /*
 346                  * Try to pre-fault the user memory to reduce instances of
 347                  * races within the kernel.  XXX workaround for kernel bug
 348                  * where kernel does a sanity check, but user faults during
 349                  * the copy can block and race against another kernel entity
 350                  * unmapping the memory in question.
 351                  */
 352                 bzero(buf, len);
 353                 cc = read(kd->vmfd, buf, len);
 354                 if (cc < 0) {
 355                         _kvm_syserr(kd, 0, "kvm_read");
 356                         return (-1);
 357                 } else if (cc < len)
 358                         _kvm_err(kd, kd->program, "short read");
 359                 return (cc);
 360         } else {
 361                 cp = buf;
 362                 while (len > 0) {
 363                         u_long pa;
 364
 365                         cc = _kvm_kvatop(kd, kva, &pa);
 366                         if (cc == 0)
 367                                 return (-1);
 368                         if (cc > len)
 369                                 cc = len;
 370                         errno = 0;
 371                         if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
 372                                 _kvm_syserr(kd, 0, _PATH_MEM);
 373                                 break;
 374                         }
 375                         bzero(cp, cc);
 376                         cc = read(kd->pmfd, cp, cc);
 377                         if (cc < 0) {
 378                                 _kvm_syserr(kd, kd->program, "kvm_read");
 379                                 break;
 380                         }
 381                         /*
 382                          * If kvm_kvatop returns a bogus value or our core
 383                          * file is truncated, we might wind up seeking beyond
 384                          * the end of the core file in which case the read will
 385                          * return 0 (EOF).
 386                          */
 387                         if (cc == 0)
 388                                 break;
 389                         cp = (char *)cp + cc;
 390                         kva += cc;
 391                         len -= cc;
 392                 }
 393                 return ((char *)cp - (char *)buf);
 394         }
 395         /* NOTREACHED */
 396 }
 397
 398 char *
 399 kvm_readstr(kvm_t *kd, u_long kva, char *buf, size_t *lenp)
 400 {
 401         size_t len, cc, pos;
 402         char ch;
 403         int asize = -1;
 404
 405         if (buf == NULL) {
 406                 asize = len = 16;
 407                 buf = malloc(len);
 408                 if (buf == NULL) {
 409                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 410                         return NULL;
 411                 }
 412         } else {
 413                 len = *lenp;
 414         }
 415
 416         if (ISALIVE(kd)) {
 417                 /*
 418                  * We're using /dev/kmem.  Just read straight from the
 419                  * device and let the active kernel do the address translation.
 420                  */
 421                 errno = 0;
 422                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 423                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 424                         return NULL;
 425                 }
 426
 427                 for (pos = 0, ch = -1; ch != 0; pos++) {
 428                         cc = read(kd->vmfd, &ch, 1);
 429                         if ((ssize_t)cc < 0) {
 430                                 _kvm_syserr(kd, 0, "kvm_readstr");
 431                                 return NULL;
 432                         } else if (cc < 1)
 433                                 _kvm_err(kd, kd->program, "short read");
 434                         if (pos == asize) {
 435                                 buf = realloc(buf, asize *= 2);
 436                                 if (buf == NULL) {
 437                                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 438                                         return NULL;
 439                                 }
 440                                 len = asize;
 441                         }
 442                         if (pos < len)
 443                                 buf[pos] = ch;
 444                 }
 445
 446                 if (lenp != NULL)
 447                         *lenp = pos;
 448                 if (pos > len)
 449                         return NULL;
 450                 else
 451                         return buf;
 452         } else {
 453                 size_t left = 0;
 454                 for (pos = 0, ch = -1; ch != 0; pos++, left--, kva++) {
 455                         if (left == 0) {
 456                                 u_long pa;
 457
 458                                 left = _kvm_kvatop(kd, kva, &pa);
 459                                 if (left == 0)
 460                                         return NULL;
 461                                 errno = 0;
 462                                 if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
 463                                         _kvm_syserr(kd, 0, _PATH_MEM);
 464                                         return NULL;
 465                                 }
 466                         }
 467                         cc = read(kd->pmfd, &ch, 1);
 468                         if ((ssize_t)cc < 0) {
 469                                 _kvm_syserr(kd, 0, "kvm_readstr");
 470                                 return NULL;
 471                         } else if (cc < 1)
 472                                 _kvm_err(kd, kd->program, "short read");
 473                         if (pos == asize) {
 474                                 buf = realloc(buf, asize *= 2);
 475                                 if (buf == NULL) {
 476                                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 477                                         return NULL;
 478                                 }
 479                                 len = asize;
 480                         }
 481                         if (pos < len)
 482                                 buf[pos] = ch;
 483                 }
 484
 485                 if (lenp != NULL)
 486                         *lenp = pos;
 487                 if (pos > len)
 488                         return NULL;
 489                 else
 490                         return buf;
 491         }
 492         /* NOTREACHED */
 493 }
 494
 495 ssize_t
 496 kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
 497 {
 498         int cc;
 499
 500         if (ISALIVE(kd)) {
 501                 /*
 502                  * Just like kvm_read, only we write.
 503                  */
 504                 errno = 0;
 505                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 506                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 507                         return (-1);
 508                 }
 509                 cc = write(kd->vmfd, buf, len);
 510                 if (cc < 0) {
 511                         _kvm_syserr(kd, 0, "kvm_write");
 512                         return (-1);
 513                 } else if (cc < len)
 514                         _kvm_err(kd, kd->program, "short write");
 515                 return (cc);
 516         } else {
 517                 _kvm_err(kd, kd->program,
 518                     "kvm_write not implemented for dead kernels");
 519                 return (-1);
 520         }
 521         /* NOTREACHED */
 522 }