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 1.11 2007/12/03 14:42:45 hasso 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
 287         /*
 288          * If we can't use the kld symbol lookup, revert to the
 289          * slow library call.
 290          */
 291         if (!ISALIVE(kd))
 292                 return (__fdnlist(kd->nlfd, nl));
 293
 294         /*
 295          * We can use the kld lookup syscall.  Go through each nlist entry
 296          * and look it up with a kldsym(2) syscall.
 297          */
 298         nvalid = 0;
 299         for (p = nl; p->n_name && p->n_name[0]; ++p) {
 300                 lookup.version = sizeof(lookup);
 301                 lookup.symname = p->n_name;
 302                 lookup.symvalue = 0;
 303                 lookup.symsize = 0;
 304
 305                 if (lookup.symname[0] == '_')
 306                         lookup.symname++;
 307
 308                 if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
 309                         p->n_type = N_TEXT;
 310                         p->n_other = 0;
 311                         p->n_desc = 0;
 312                         p->n_value = lookup.symvalue;
 313                         ++nvalid;
 314                         /* lookup.symsize */
 315                 }
 316         }
 317         /*
 318          * Return the number of entries that weren't found.
 319          */
 320         return ((p - nl) - nvalid);
 321 }
 322
 323 ssize_t
 324 kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
 325 {
 326         int cc;
 327         void *cp;
 328
 329         if (ISALIVE(kd)) {
 330                 /*
 331                  * We're using /dev/kmem.  Just read straight from the
 332                  * device and let the active kernel do the address translation.
 333                  */
 334                 errno = 0;
 335                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 336                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 337                         return (-1);
 338                 }
 339
 340                 /*
 341                  * Try to pre-fault the user memory to reduce instances of
 342                  * races within the kernel.  XXX workaround for kernel bug
 343                  * where kernel does a sanity check, but user faults during
 344                  * the copy can block and race against another kernel entity
 345                  * unmapping the memory in question.
 346                  */
 347                 bzero(buf, len);
 348                 cc = read(kd->vmfd, buf, len);
 349                 if (cc < 0) {
 350                         _kvm_syserr(kd, 0, "kvm_read");
 351                         return (-1);
 352                 } else if (cc < len)
 353                         _kvm_err(kd, kd->program, "short read");
 354                 return (cc);
 355         } else {
 356                 cp = buf;
 357                 while (len > 0) {
 358                         u_long pa;
 359
 360                         cc = _kvm_kvatop(kd, kva, &pa);
 361                         if (cc == 0)
 362                                 return (-1);
 363                         if (cc > len)
 364                                 cc = len;
 365                         errno = 0;
 366                         if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
 367                                 _kvm_syserr(kd, 0, _PATH_MEM);
 368                                 break;
 369                         }
 370                         bzero(cp, cc);
 371                         cc = read(kd->pmfd, cp, cc);
 372                         if (cc < 0) {
 373                                 _kvm_syserr(kd, kd->program, "kvm_read");
 374                                 break;
 375                         }
 376                         /*
 377                          * If kvm_kvatop returns a bogus value or our core
 378                          * file is truncated, we might wind up seeking beyond
 379                          * the end of the core file in which case the read will
 380                          * return 0 (EOF).
 381                          */
 382                         if (cc == 0)
 383                                 break;
 384                         cp = (char *)cp + cc;
 385                         kva += cc;
 386                         len -= cc;
 387                 }
 388                 return ((char *)cp - (char *)buf);
 389         }
 390         /* NOTREACHED */
 391 }
 392
 393 char *
 394 kvm_readstr(kvm_t *kd, u_long kva, char *buf, size_t *lenp)
 395 {
 396         size_t len, cc, pos;
 397         char ch;
 398         int asize = -1;
 399
 400         if (buf == NULL) {
 401                 asize = len = 16;
 402                 buf = malloc(len);
 403                 if (buf == NULL) {
 404                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 405                         return NULL;
 406                 }
 407         } else {
 408                 len = *lenp;
 409         }
 410
 411         if (ISALIVE(kd)) {
 412                 /*
 413                  * We're using /dev/kmem.  Just read straight from the
 414                  * device and let the active kernel do the address translation.
 415                  */
 416                 errno = 0;
 417                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 418                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 419                         return NULL;
 420                 }
 421
 422                 for (pos = 0, ch = -1; ch != 0; pos++) {
 423                         cc = read(kd->vmfd, &ch, 1);
 424                         if ((ssize_t)cc < 0) {
 425                                 _kvm_syserr(kd, 0, "kvm_readstr");
 426                                 return NULL;
 427                         } else if (cc < 1)
 428                                 _kvm_err(kd, kd->program, "short read");
 429                         if (pos == asize) {
 430                                 buf = realloc(buf, asize *= 2);
 431                                 if (buf == NULL) {
 432                                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 433                                         return NULL;
 434                                 }
 435                                 len = asize;
 436                         }
 437                         if (pos < len)
 438                                 buf[pos] = ch;
 439                 }
 440
 441                 if (lenp != NULL)
 442                         *lenp = pos;
 443                 if (pos > len)
 444                         return NULL;
 445                 else
 446                         return buf;
 447         } else {
 448                 size_t left = 0;
 449                 for (pos = 0, ch = -1; ch != 0; pos++, left--, kva++) {
 450                         if (left == 0) {
 451                                 u_long pa;
 452
 453                                 left = _kvm_kvatop(kd, kva, &pa);
 454                                 if (left == 0)
 455                                         return NULL;
 456                                 errno = 0;
 457                                 if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
 458                                         _kvm_syserr(kd, 0, _PATH_MEM);
 459                                         return NULL;
 460                                 }
 461                         }
 462                         cc = read(kd->pmfd, &ch, 1);
 463                         if ((ssize_t)cc < 0) {
 464                                 _kvm_syserr(kd, 0, "kvm_readstr");
 465                                 return NULL;
 466                         } else if (cc < 1)
 467                                 _kvm_err(kd, kd->program, "short read");
 468                         if (pos == asize) {
 469                                 buf = realloc(buf, asize *= 2);
 470                                 if (buf == NULL) {
 471                                         _kvm_syserr(kd, kd->program, "kvm_readstr");
 472                                         return NULL;
 473                                 }
 474                                 len = asize;
 475                         }
 476                         if (pos < len)
 477                                 buf[pos] = ch;
 478                 }
 479
 480                 if (lenp != NULL)
 481                         *lenp = pos;
 482                 if (pos > len)
 483                         return NULL;
 484                 else
 485                         return buf;
 486         }
 487         /* NOTREACHED */
 488 }
 489
 490 ssize_t
 491 kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
 492 {
 493         int cc;
 494
 495         if (ISALIVE(kd)) {
 496                 /*
 497                  * Just like kvm_read, only we write.
 498                  */
 499                 errno = 0;
 500                 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
 501                         _kvm_err(kd, 0, "invalid address (%x)", kva);
 502                         return (-1);
 503                 }
 504                 cc = write(kd->vmfd, buf, len);
 505                 if (cc < 0) {
 506                         _kvm_syserr(kd, 0, "kvm_write");
 507                         return (-1);
 508                 } else if (cc < len)
 509                         _kvm_err(kd, kd->program, "short write");
 510                 return (cc);
 511         } else {
 512                 _kvm_err(kd, kd->program,
 513                     "kvm_write not implemented for dead kernels");
 514                 return (-1);
 515         }
 516         /* NOTREACHED */
 517 }