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