crypto/openssh/misc.c

   1 /* $OpenBSD: misc.c,v 1.113 2017/08/18 05:48:04 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  * Copyright (c) 2005,2006 Damien Miller.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #include <sys/types.h>
  30 #include <sys/ioctl.h>
  31 #include <sys/socket.h>
  32 #include <sys/stat.h>
  33 #include <sys/time.h>
  34 #include <sys/wait.h>
  35 #include <sys/un.h>
  36
  37 #include <limits.h>
  38 #ifdef HAVE_LIBGEN_H
  39 # include <libgen.h>
  40 #endif
  41 #include <signal.h>
  42 #include <stdarg.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46 #include <time.h>
  47 #include <unistd.h>
  48
  49 #include <netinet/in.h>
  50 #include <netinet/in_systm.h>
  51 #include <netinet/ip.h>
  52 #include <netinet/tcp.h>
  53
  54 #include <ctype.h>
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <netdb.h>
  58 #ifdef HAVE_PATHS_H
  59 # include <paths.h>
  60 #include <pwd.h>
  61 #endif
  62 #ifdef SSH_TUN_OPENBSD
  63 #include <net/if.h>
  64 #endif
  65
  66 #include "xmalloc.h"
  67 #include "misc.h"
  68 #include "log.h"
  69 #include "ssh.h"
  70 #include "sshbuf.h"
  71 #include "ssherr.h"
  72 #include "uidswap.h"
  73 #include "platform.h"
  74
  75 /* remove newline at end of string */
  76 char *
  77 chop(char *s)
  78 {
  79         char *t = s;
  80         while (*t) {
  81                 if (*t == '\n' || *t == '\r') {
  82                         *t = '\0';
  83                         return s;
  84                 }
  85                 t++;
  86         }
  87         return s;
  88
  89 }
  90
  91 /* set/unset filedescriptor to non-blocking */
  92 int
  93 set_nonblock(int fd)
  94 {
  95         int val;
  96
  97         val = fcntl(fd, F_GETFL);
  98         if (val < 0) {
  99                 error("fcntl(%d, F_GETFL): %s", fd, strerror(errno));
 100                 return (-1);
 101         }
 102         if (val & O_NONBLOCK) {
 103                 debug3("fd %d is O_NONBLOCK", fd);
 104                 return (0);
 105         }
 106         debug2("fd %d setting O_NONBLOCK", fd);
 107         val |= O_NONBLOCK;
 108         if (fcntl(fd, F_SETFL, val) == -1) {
 109                 debug("fcntl(%d, F_SETFL, O_NONBLOCK): %s", fd,
 110                     strerror(errno));
 111                 return (-1);
 112         }
 113         return (0);
 114 }
 115
 116 int
 117 unset_nonblock(int fd)
 118 {
 119         int val;
 120
 121         val = fcntl(fd, F_GETFL);
 122         if (val < 0) {
 123                 error("fcntl(%d, F_GETFL): %s", fd, strerror(errno));
 124                 return (-1);
 125         }
 126         if (!(val & O_NONBLOCK)) {
 127                 debug3("fd %d is not O_NONBLOCK", fd);
 128                 return (0);
 129         }
 130         debug("fd %d clearing O_NONBLOCK", fd);
 131         val &= ~O_NONBLOCK;
 132         if (fcntl(fd, F_SETFL, val) == -1) {
 133                 debug("fcntl(%d, F_SETFL, ~O_NONBLOCK): %s",
 134                     fd, strerror(errno));
 135                 return (-1);
 136         }
 137         return (0);
 138 }
 139
 140 const char *
 141 ssh_gai_strerror(int gaierr)
 142 {
 143         if (gaierr == EAI_SYSTEM && errno != 0)
 144                 return strerror(errno);
 145         return gai_strerror(gaierr);
 146 }
 147
 148 /* disable nagle on socket */
 149 void
 150 set_nodelay(int fd)
 151 {
 152         int opt;
 153         socklen_t optlen;
 154
 155         optlen = sizeof opt;
 156         if (getsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, &optlen) == -1) {
 157                 debug("getsockopt TCP_NODELAY: %.100s", strerror(errno));
 158                 return;
 159         }
 160         if (opt == 1) {
 161                 debug2("fd %d is TCP_NODELAY", fd);
 162                 return;
 163         }
 164         opt = 1;
 165         debug2("fd %d setting TCP_NODELAY", fd);
 166         if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof opt) == -1)
 167                 error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
 168 }
 169
 170 /* Characters considered whitespace in strsep calls. */
 171 #define WHITESPACE " \t\r\n"
 172 #define QUOTE   "\""
 173
 174 /* return next token in configuration line */
 175 char *
 176 strdelim(char **s)
 177 {
 178         char *old;
 179         int wspace = 0;
 180
 181         if (*s == NULL)
 182                 return NULL;
 183
 184         old = *s;
 185
 186         *s = strpbrk(*s, WHITESPACE QUOTE "=");
 187         if (*s == NULL)
 188                 return (old);
 189
 190         if (*s[0] == '\"') {
 191                 memmove(*s, *s + 1, strlen(*s)); /* move nul too */
 192                 /* Find matching quote */
 193                 if ((*s = strpbrk(*s, QUOTE)) == NULL) {
 194                         return (NULL);          /* no matching quote */
 195                 } else {
 196                         *s[0] = '\0';
 197                         *s += strspn(*s + 1, WHITESPACE) + 1;
 198                         return (old);
 199                 }
 200         }
 201
 202         /* Allow only one '=' to be skipped */
 203         if (*s[0] == '=')
 204                 wspace = 1;
 205         *s[0] = '\0';
 206
 207         /* Skip any extra whitespace after first token */
 208         *s += strspn(*s + 1, WHITESPACE) + 1;
 209         if (*s[0] == '=' && !wspace)
 210                 *s += strspn(*s + 1, WHITESPACE) + 1;
 211
 212         return (old);
 213 }
 214
 215 struct passwd *
 216 pwcopy(struct passwd *pw)
 217 {
 218         struct passwd *copy = xcalloc(1, sizeof(*copy));
 219
 220         copy->pw_name = xstrdup(pw->pw_name);
 221         copy->pw_passwd = xstrdup(pw->pw_passwd);
 222 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
 223         copy->pw_gecos = xstrdup(pw->pw_gecos);
 224 #endif
 225         copy->pw_uid = pw->pw_uid;
 226         copy->pw_gid = pw->pw_gid;
 227 #ifdef HAVE_STRUCT_PASSWD_PW_EXPIRE
 228         copy->pw_expire = pw->pw_expire;
 229 #endif
 230 #ifdef HAVE_STRUCT_PASSWD_PW_CHANGE
 231         copy->pw_change = pw->pw_change;
 232 #endif
 233 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
 234         copy->pw_class = xstrdup(pw->pw_class);
 235 #endif
 236         copy->pw_dir = xstrdup(pw->pw_dir);
 237         copy->pw_shell = xstrdup(pw->pw_shell);
 238         return copy;
 239 }
 240
 241 /*
 242  * Convert ASCII string to TCP/IP port number.
 243  * Port must be >=0 and <=65535.
 244  * Return -1 if invalid.
 245  */
 246 int
 247 a2port(const char *s)
 248 {
 249         long long port;
 250         const char *errstr;
 251
 252         port = strtonum(s, 0, 65535, &errstr);
 253         if (errstr != NULL)
 254                 return -1;
 255         return (int)port;
 256 }
 257
 258 int
 259 a2tun(const char *s, int *remote)
 260 {
 261         const char *errstr = NULL;
 262         char *sp, *ep;
 263         int tun;
 264
 265         if (remote != NULL) {
 266                 *remote = SSH_TUNID_ANY;
 267                 sp = xstrdup(s);
 268                 if ((ep = strchr(sp, ':')) == NULL) {
 269                         free(sp);
 270                         return (a2tun(s, NULL));
 271                 }
 272                 ep[0] = '\0'; ep++;
 273                 *remote = a2tun(ep, NULL);
 274                 tun = a2tun(sp, NULL);
 275                 free(sp);
 276                 return (*remote == SSH_TUNID_ERR ? *remote : tun);
 277         }
 278
 279         if (strcasecmp(s, "any") == 0)
 280                 return (SSH_TUNID_ANY);
 281
 282         tun = strtonum(s, 0, SSH_TUNID_MAX, &errstr);
 283         if (errstr != NULL)
 284                 return (SSH_TUNID_ERR);
 285
 286         return (tun);
 287 }
 288
 289 #define SECONDS         1
 290 #define MINUTES         (SECONDS * 60)
 291 #define HOURS           (MINUTES * 60)
 292 #define DAYS            (HOURS * 24)
 293 #define WEEKS           (DAYS * 7)
 294
 295 /*
 296  * Convert a time string into seconds; format is
 297  * a sequence of:
 298  *      time[qualifier]
 299  *
 300  * Valid time qualifiers are:
 301  *      <none>  seconds
 302  *      s|S     seconds
 303  *      m|M     minutes
 304  *      h|H     hours
 305  *      d|D     days
 306  *      w|W     weeks
 307  *
 308  * Examples:
 309  *      90m     90 minutes
 310  *      1h30m   90 minutes
 311  *      2d      2 days
 312  *      1w      1 week
 313  *
 314  * Return -1 if time string is invalid.
 315  */
 316 long
 317 convtime(const char *s)
 318 {
 319         long total, secs, multiplier = 1;
 320         const char *p;
 321         char *endp;
 322
 323         errno = 0;
 324         total = 0;
 325         p = s;
 326
 327         if (p == NULL || *p == '\0')
 328                 return -1;
 329
 330         while (*p) {
 331                 secs = strtol(p, &endp, 10);
 332                 if (p == endp ||
 333                     (errno == ERANGE && (secs == LONG_MIN || secs == LONG_MAX)) ||
 334                     secs < 0)
 335                         return -1;
 336
 337                 switch (*endp++) {
 338                 case '\0':
 339                         endp--;
 340                         break;
 341                 case 's':
 342                 case 'S':
 343                         break;
 344                 case 'm':
 345                 case 'M':
 346                         multiplier = MINUTES;
 347                         break;
 348                 case 'h':
 349                 case 'H':
 350                         multiplier = HOURS;
 351                         break;
 352                 case 'd':
 353                 case 'D':
 354                         multiplier = DAYS;
 355                         break;
 356                 case 'w':
 357                 case 'W':
 358                         multiplier = WEEKS;
 359                         break;
 360                 default:
 361                         return -1;
 362                 }
 363                 if (secs >= LONG_MAX / multiplier)
 364                         return -1;
 365                 secs *= multiplier;
 366                 if  (total >= LONG_MAX - secs)
 367                         return -1;
 368                 total += secs;
 369                 if (total < 0)
 370                         return -1;
 371                 p = endp;
 372         }
 373
 374         return total;
 375 }
 376
 377 /*
 378  * Returns a standardized host+port identifier string.
 379  * Caller must free returned string.
 380  */
 381 char *
 382 put_host_port(const char *host, u_short port)
 383 {
 384         char *hoststr;
 385
 386         if (port == 0 || port == SSH_DEFAULT_PORT)
 387                 return(xstrdup(host));
 388         if (asprintf(&hoststr, "[%s]:%d", host, (int)port) < 0)
 389                 fatal("put_host_port: asprintf: %s", strerror(errno));
 390         debug3("put_host_port: %s", hoststr);
 391         return hoststr;
 392 }
 393
 394 /*
 395  * Search for next delimiter between hostnames/addresses and ports.
 396  * Argument may be modified (for termination).
 397  * Returns *cp if parsing succeeds.
 398  * *cp is set to the start of the next delimiter, if one was found.
 399  * If this is the last field, *cp is set to NULL.
 400  */
 401 char *
 402 hpdelim(char **cp)
 403 {
 404         char *s, *old;
 405
 406         if (cp == NULL || *cp == NULL)
 407                 return NULL;
 408
 409         old = s = *cp;
 410         if (*s == '[') {
 411                 if ((s = strchr(s, ']')) == NULL)
 412                         return NULL;
 413                 else
 414                         s++;
 415         } else if ((s = strpbrk(s, ":/")) == NULL)
 416                 s = *cp + strlen(*cp); /* skip to end (see first case below) */
 417
 418         switch (*s) {
 419         case '\0':
 420                 *cp = NULL;     /* no more fields*/
 421                 break;
 422
 423         case ':':
 424         case '/':
 425                 *s = '\0';      /* terminate */
 426                 *cp = s + 1;
 427                 break;
 428
 429         default:
 430                 return NULL;
 431         }
 432
 433         return old;
 434 }
 435
 436 char *
 437 cleanhostname(char *host)
 438 {
 439         if (*host == '[' && host[strlen(host) - 1] == ']') {
 440                 host[strlen(host) - 1] = '\0';
 441                 return (host + 1);
 442         } else
 443                 return host;
 444 }
 445
 446 char *
 447 colon(char *cp)
 448 {
 449         int flag = 0;
 450
 451         if (*cp == ':')         /* Leading colon is part of file name. */
 452                 return NULL;
 453         if (*cp == '[')
 454                 flag = 1;
 455
 456         for (; *cp; ++cp) {
 457                 if (*cp == '@' && *(cp+1) == '[')
 458                         flag = 1;
 459                 if (*cp == ']' && *(cp+1) == ':' && flag)
 460                         return (cp+1);
 461                 if (*cp == ':' && !flag)
 462                         return (cp);
 463                 if (*cp == '/')
 464                         return NULL;
 465         }
 466         return NULL;
 467 }
 468
 469 /*
 470  * Parse a [user@]host[:port] string.
 471  * Caller must free returned user and host.
 472  * Any of the pointer return arguments may be NULL (useful for syntax checking).
 473  * If user was not specified then *userp will be set to NULL.
 474  * If port was not specified then *portp will be -1.
 475  * Returns 0 on success, -1 on failure.
 476  */
 477 int
 478 parse_user_host_port(const char *s, char **userp, char **hostp, int *portp)
 479 {
 480         char *sdup, *cp, *tmp;
 481         char *user = NULL, *host = NULL;
 482         int port = -1, ret = -1;
 483
 484         if (userp != NULL)
 485                 *userp = NULL;
 486         if (hostp != NULL)
 487                 *hostp = NULL;
 488         if (portp != NULL)
 489                 *portp = -1;
 490
 491         if ((sdup = tmp = strdup(s)) == NULL)
 492                 return -1;
 493         /* Extract optional username */
 494         if ((cp = strchr(tmp, '@')) != NULL) {
 495                 *cp = '\0';
 496                 if (*tmp == '\0')
 497                         goto out;
 498                 if ((user = strdup(tmp)) == NULL)
 499                         goto out;
 500                 tmp = cp + 1;
 501         }
 502         /* Extract mandatory hostname */
 503         if ((cp = hpdelim(&tmp)) == NULL || *cp == '\0')
 504                 goto out;
 505         host = xstrdup(cleanhostname(cp));
 506         /* Convert and verify optional port */
 507         if (tmp != NULL && *tmp != '\0') {
 508                 if ((port = a2port(tmp)) <= 0)
 509                         goto out;
 510         }
 511         /* Success */
 512         if (userp != NULL) {
 513                 *userp = user;
 514                 user = NULL;
 515         }
 516         if (hostp != NULL) {
 517                 *hostp = host;
 518                 host = NULL;
 519         }
 520         if (portp != NULL)
 521                 *portp = port;
 522         ret = 0;
 523  out:
 524         free(sdup);
 525         free(user);
 526         free(host);
 527         return ret;
 528 }
 529
 530 /* function to assist building execv() arguments */
 531 void
 532 addargs(arglist *args, char *fmt, ...)
 533 {
 534         va_list ap;
 535         char *cp;
 536         u_int nalloc;
 537         int r;
 538
 539         va_start(ap, fmt);
 540         r = vasprintf(&cp, fmt, ap);
 541         va_end(ap);
 542         if (r == -1)
 543                 fatal("addargs: argument too long");
 544
 545         nalloc = args->nalloc;
 546         if (args->list == NULL) {
 547                 nalloc = 32;
 548                 args->num = 0;
 549         } else if (args->num+2 >= nalloc)
 550                 nalloc *= 2;
 551
 552         args->list = xrecallocarray(args->list, args->nalloc, nalloc, sizeof(char *));
 553         args->nalloc = nalloc;
 554         args->list[args->num++] = cp;
 555         args->list[args->num] = NULL;
 556 }
 557
 558 void
 559 replacearg(arglist *args, u_int which, char *fmt, ...)
 560 {
 561         va_list ap;
 562         char *cp;
 563         int r;
 564
 565         va_start(ap, fmt);
 566         r = vasprintf(&cp, fmt, ap);
 567         va_end(ap);
 568         if (r == -1)
 569                 fatal("replacearg: argument too long");
 570
 571         if (which >= args->num)
 572                 fatal("replacearg: tried to replace invalid arg %d >= %d",
 573                     which, args->num);
 574         free(args->list[which]);
 575         args->list[which] = cp;
 576 }
 577
 578 void
 579 freeargs(arglist *args)
 580 {
 581         u_int i;
 582
 583         if (args->list != NULL) {
 584                 for (i = 0; i < args->num; i++)
 585                         free(args->list[i]);
 586                 free(args->list);
 587                 args->nalloc = args->num = 0;
 588                 args->list = NULL;
 589         }
 590 }
 591
 592 /*
 593  * Expands tildes in the file name.  Returns data allocated by xmalloc.
 594  * Warning: this calls getpw*.
 595  */
 596 char *
 597 tilde_expand_filename(const char *filename, uid_t uid)
 598 {
 599         const char *path, *sep;
 600         char user[128], *ret;
 601         struct passwd *pw;
 602         u_int len, slash;
 603
 604         if (*filename != '~')
 605                 return (xstrdup(filename));
 606         filename++;
 607
 608         path = strchr(filename, '/');
 609         if (path != NULL && path > filename) {          /* ~user/path */
 610                 slash = path - filename;
 611                 if (slash > sizeof(user) - 1)
 612                         fatal("tilde_expand_filename: ~username too long");
 613                 memcpy(user, filename, slash);
 614                 user[slash] = '\0';
 615                 if ((pw = getpwnam(user)) == NULL)
 616                         fatal("tilde_expand_filename: No such user %s", user);
 617         } else if ((pw = getpwuid(uid)) == NULL)        /* ~/path */
 618                 fatal("tilde_expand_filename: No such uid %ld", (long)uid);
 619
 620         /* Make sure directory has a trailing '/' */
 621         len = strlen(pw->pw_dir);
 622         if (len == 0 || pw->pw_dir[len - 1] != '/')
 623                 sep = "/";
 624         else
 625                 sep = "";
 626
 627         /* Skip leading '/' from specified path */
 628         if (path != NULL)
 629                 filename = path + 1;
 630
 631         if (xasprintf(&ret, "%s%s%s", pw->pw_dir, sep, filename) >= PATH_MAX)
 632                 fatal("tilde_expand_filename: Path too long");
 633
 634         return (ret);
 635 }
 636
 637 /*
 638  * Expand a string with a set of %[char] escapes. A number of escapes may be
 639  * specified as (char *escape_chars, char *replacement) pairs. The list must
 640  * be terminated by a NULL escape_char. Returns replaced string in memory
 641  * allocated by xmalloc.
 642  */
 643 char *
 644 percent_expand(const char *string, ...)
 645 {
 646 #define EXPAND_MAX_KEYS 16
 647         u_int num_keys, i, j;
 648         struct {
 649                 const char *key;
 650                 const char *repl;
 651         } keys[EXPAND_MAX_KEYS];
 652         char buf[4096];
 653         va_list ap;
 654
 655         /* Gather keys */
 656         va_start(ap, string);
 657         for (num_keys = 0; num_keys < EXPAND_MAX_KEYS; num_keys++) {
 658                 keys[num_keys].key = va_arg(ap, char *);
 659                 if (keys[num_keys].key == NULL)
 660                         break;
 661                 keys[num_keys].repl = va_arg(ap, char *);
 662                 if (keys[num_keys].repl == NULL)
 663                         fatal("%s: NULL replacement", __func__);
 664         }
 665         if (num_keys == EXPAND_MAX_KEYS && va_arg(ap, char *) != NULL)
 666                 fatal("%s: too many keys", __func__);
 667         va_end(ap);
 668
 669         /* Expand string */
 670         *buf = '\0';
 671         for (i = 0; *string != '\0'; string++) {
 672                 if (*string != '%') {
 673  append:
 674                         buf[i++] = *string;
 675                         if (i >= sizeof(buf))
 676                                 fatal("%s: string too long", __func__);
 677                         buf[i] = '\0';
 678                         continue;
 679                 }
 680                 string++;
 681                 /* %% case */
 682                 if (*string == '%')
 683                         goto append;
 684                 if (*string == '\0')
 685                         fatal("%s: invalid format", __func__);
 686                 for (j = 0; j < num_keys; j++) {
 687                         if (strchr(keys[j].key, *string) != NULL) {
 688                                 i = strlcat(buf, keys[j].repl, sizeof(buf));
 689                                 if (i >= sizeof(buf))
 690                                         fatal("%s: string too long", __func__);
 691                                 break;
 692                         }
 693                 }
 694                 if (j >= num_keys)
 695                         fatal("%s: unknown key %%%c", __func__, *string);
 696         }
 697         return (xstrdup(buf));
 698 #undef EXPAND_MAX_KEYS
 699 }
 700
 701 /*
 702  * Read an entire line from a public key file into a static buffer, discarding
 703  * lines that exceed the buffer size.  Returns 0 on success, -1 on failure.
 704  */
 705 int
 706 read_keyfile_line(FILE *f, const char *filename, char *buf, size_t bufsz,
 707    u_long *lineno)
 708 {
 709         while (fgets(buf, bufsz, f) != NULL) {
 710                 if (buf[0] == '\0')
 711                         continue;
 712                 (*lineno)++;
 713                 if (buf[strlen(buf) - 1] == '\n' || feof(f)) {
 714                         return 0;
 715                 } else {
 716                         debug("%s: %s line %lu exceeds size limit", __func__,
 717                             filename, *lineno);
 718                         /* discard remainder of line */
 719                         while (fgetc(f) != '\n' && !feof(f))
 720                                 ;       /* nothing */
 721                 }
 722         }
 723         return -1;
 724 }
 725
 726 int
 727 tun_open(int tun, int mode)
 728 {
 729 #if defined(CUSTOM_SYS_TUN_OPEN)
 730         return (sys_tun_open(tun, mode));
 731 #elif defined(SSH_TUN_OPENBSD)
 732         struct ifreq ifr;
 733         char name[100];
 734         int fd = -1, sock;
 735         const char *tunbase = "tun";
 736
 737         if (mode == SSH_TUNMODE_ETHERNET)
 738                 tunbase = "tap";
 739
 740         /* Open the tunnel device */
 741         if (tun <= SSH_TUNID_MAX) {
 742                 snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
 743                 fd = open(name, O_RDWR);
 744         } else if (tun == SSH_TUNID_ANY) {
 745                 for (tun = 100; tun >= 0; tun--) {
 746                         snprintf(name, sizeof(name), "/dev/%s%d",
 747                             tunbase, tun);
 748                         if ((fd = open(name, O_RDWR)) >= 0)
 749                                 break;
 750                 }
 751         } else {
 752                 debug("%s: invalid tunnel %u", __func__, tun);
 753                 return -1;
 754         }
 755
 756         if (fd < 0) {
 757                 debug("%s: %s open: %s", __func__, name, strerror(errno));
 758                 return -1;
 759         }
 760
 761         debug("%s: %s mode %d fd %d", __func__, name, mode, fd);
 762
 763         /* Bring interface up if it is not already */
 764         snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
 765         if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
 766                 goto failed;
 767
 768         if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1) {
 769                 debug("%s: get interface %s flags: %s", __func__,
 770                     ifr.ifr_name, strerror(errno));
 771                 goto failed;
 772         }
 773
 774         if (!(ifr.ifr_flags & IFF_UP)) {
 775                 ifr.ifr_flags |= IFF_UP;
 776                 if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1) {
 777                         debug("%s: activate interface %s: %s", __func__,
 778                             ifr.ifr_name, strerror(errno));
 779                         goto failed;
 780                 }
 781         }
 782
 783         close(sock);
 784         return fd;
 785
 786  failed:
 787         if (fd >= 0)
 788                 close(fd);
 789         if (sock >= 0)
 790                 close(sock);
 791         return -1;
 792 #else
 793         error("Tunnel interfaces are not supported on this platform");
 794         return (-1);
 795 #endif
 796 }
 797
 798 void
 799 sanitise_stdfd(void)
 800 {
 801         int nullfd, dupfd;
 802
 803         if ((nullfd = dupfd = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 804                 fprintf(stderr, "Couldn't open /dev/null: %s\n",
 805                     strerror(errno));
 806                 exit(1);
 807         }
 808         while (++dupfd <= STDERR_FILENO) {
 809                 /* Only populate closed fds. */
 810                 if (fcntl(dupfd, F_GETFL) == -1 && errno == EBADF) {
 811                         if (dup2(nullfd, dupfd) == -1) {
 812                                 fprintf(stderr, "dup2: %s\n", strerror(errno));
 813                                 exit(1);
 814                         }
 815                 }
 816         }
 817         if (nullfd > STDERR_FILENO)
 818                 close(nullfd);
 819 }
 820
 821 char *
 822 tohex(const void *vp, size_t l)
 823 {
 824         const u_char *p = (const u_char *)vp;
 825         char b[3], *r;
 826         size_t i, hl;
 827
 828         if (l > 65536)
 829                 return xstrdup("tohex: length > 65536");
 830
 831         hl = l * 2 + 1;
 832         r = xcalloc(1, hl);
 833         for (i = 0; i < l; i++) {
 834                 snprintf(b, sizeof(b), "%02x", p[i]);
 835                 strlcat(r, b, hl);
 836         }
 837         return (r);
 838 }
 839
 840 u_int64_t
 841 get_u64(const void *vp)
 842 {
 843         const u_char *p = (const u_char *)vp;
 844         u_int64_t v;
 845
 846         v  = (u_int64_t)p[0] << 56;
 847         v |= (u_int64_t)p[1] << 48;
 848         v |= (u_int64_t)p[2] << 40;
 849         v |= (u_int64_t)p[3] << 32;
 850         v |= (u_int64_t)p[4] << 24;
 851         v |= (u_int64_t)p[5] << 16;
 852         v |= (u_int64_t)p[6] << 8;
 853         v |= (u_int64_t)p[7];
 854
 855         return (v);
 856 }
 857
 858 u_int32_t
 859 get_u32(const void *vp)
 860 {
 861         const u_char *p = (const u_char *)vp;
 862         u_int32_t v;
 863
 864         v  = (u_int32_t)p[0] << 24;
 865         v |= (u_int32_t)p[1] << 16;
 866         v |= (u_int32_t)p[2] << 8;
 867         v |= (u_int32_t)p[3];
 868
 869         return (v);
 870 }
 871
 872 u_int32_t
 873 get_u32_le(const void *vp)
 874 {
 875         const u_char *p = (const u_char *)vp;
 876         u_int32_t v;
 877
 878         v  = (u_int32_t)p[0];
 879         v |= (u_int32_t)p[1] << 8;
 880         v |= (u_int32_t)p[2] << 16;
 881         v |= (u_int32_t)p[3] << 24;
 882
 883         return (v);
 884 }
 885
 886 u_int16_t
 887 get_u16(const void *vp)
 888 {
 889         const u_char *p = (const u_char *)vp;
 890         u_int16_t v;
 891
 892         v  = (u_int16_t)p[0] << 8;
 893         v |= (u_int16_t)p[1];
 894
 895         return (v);
 896 }
 897
 898 void
 899 put_u64(void *vp, u_int64_t v)
 900 {
 901         u_char *p = (u_char *)vp;
 902
 903         p[0] = (u_char)(v >> 56) & 0xff;
 904         p[1] = (u_char)(v >> 48) & 0xff;
 905         p[2] = (u_char)(v >> 40) & 0xff;
 906         p[3] = (u_char)(v >> 32) & 0xff;
 907         p[4] = (u_char)(v >> 24) & 0xff;
 908         p[5] = (u_char)(v >> 16) & 0xff;
 909         p[6] = (u_char)(v >> 8) & 0xff;
 910         p[7] = (u_char)v & 0xff;
 911 }
 912
 913 void
 914 put_u32(void *vp, u_int32_t v)
 915 {
 916         u_char *p = (u_char *)vp;
 917
 918         p[0] = (u_char)(v >> 24) & 0xff;
 919         p[1] = (u_char)(v >> 16) & 0xff;
 920         p[2] = (u_char)(v >> 8) & 0xff;
 921         p[3] = (u_char)v & 0xff;
 922 }
 923
 924 void
 925 put_u32_le(void *vp, u_int32_t v)
 926 {
 927         u_char *p = (u_char *)vp;
 928
 929         p[0] = (u_char)v & 0xff;
 930         p[1] = (u_char)(v >> 8) & 0xff;
 931         p[2] = (u_char)(v >> 16) & 0xff;
 932         p[3] = (u_char)(v >> 24) & 0xff;
 933 }
 934
 935 void
 936 put_u16(void *vp, u_int16_t v)
 937 {
 938         u_char *p = (u_char *)vp;
 939
 940         p[0] = (u_char)(v >> 8) & 0xff;
 941         p[1] = (u_char)v & 0xff;
 942 }
 943
 944 void
 945 ms_subtract_diff(struct timeval *start, int *ms)
 946 {
 947         struct timeval diff, finish;
 948
 949         gettimeofday(&finish, NULL);
 950         timersub(&finish, start, &diff);
 951         *ms -= (diff.tv_sec * 1000) + (diff.tv_usec / 1000);
 952 }
 953
 954 void
 955 ms_to_timeval(struct timeval *tv, int ms)
 956 {
 957         if (ms < 0)
 958                 ms = 0;
 959         tv->tv_sec = ms / 1000;
 960         tv->tv_usec = (ms % 1000) * 1000;
 961 }
 962
 963 time_t
 964 monotime(void)
 965 {
 966 #if defined(HAVE_CLOCK_GETTIME) && \
 967     (defined(CLOCK_MONOTONIC) || defined(CLOCK_BOOTTIME))
 968         struct timespec ts;
 969         static int gettime_failed = 0;
 970
 971         if (!gettime_failed) {
 972 #if defined(CLOCK_BOOTTIME)
 973                 if (clock_gettime(CLOCK_BOOTTIME, &ts) == 0)
 974                         return (ts.tv_sec);
 975 #endif
 976 #if defined(CLOCK_MONOTONIC)
 977                 if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
 978                         return (ts.tv_sec);
 979 #endif
 980                 debug3("clock_gettime: %s", strerror(errno));
 981                 gettime_failed = 1;
 982         }
 983 #endif /* HAVE_CLOCK_GETTIME && (CLOCK_MONOTONIC || CLOCK_BOOTTIME */
 984
 985         return time(NULL);
 986 }
 987
 988 double
 989 monotime_double(void)
 990 {
 991 #if defined(HAVE_CLOCK_GETTIME) && \
 992     (defined(CLOCK_MONOTONIC) || defined(CLOCK_BOOTTIME))
 993         struct timespec ts;
 994         static int gettime_failed = 0;
 995
 996         if (!gettime_failed) {
 997 #if defined(CLOCK_BOOTTIME)
 998                 if (clock_gettime(CLOCK_BOOTTIME, &ts) == 0)
 999                         return (ts.tv_sec + (double)ts.tv_nsec / 1000000000);
1000 #endif
1001 #if defined(CLOCK_MONOTONIC)
1002                 if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
1003                         return (ts.tv_sec + (double)ts.tv_nsec / 1000000000);
1004 #endif
1005                 debug3("clock_gettime: %s", strerror(errno));
1006                 gettime_failed = 1;
1007         }
1008 #endif /* HAVE_CLOCK_GETTIME && (CLOCK_MONOTONIC || CLOCK_BOOTTIME */
1009
1010         return (double)time(NULL);
1011 }
1012
1013 void
1014 bandwidth_limit_init(struct bwlimit *bw, u_int64_t kbps, size_t buflen)
1015 {
1016         bw->buflen = buflen;
1017         bw->rate = kbps;
1018         bw->thresh = bw->rate;
1019         bw->lamt = 0;
1020         timerclear(&bw->bwstart);
1021         timerclear(&bw->bwend);
1022 }
1023
1024 /* Callback from read/write loop to insert bandwidth-limiting delays */
1025 void
1026 bandwidth_limit(struct bwlimit *bw, size_t read_len)
1027 {
1028         u_int64_t waitlen;
1029         struct timespec ts, rm;
1030
1031         if (!timerisset(&bw->bwstart)) {
1032                 gettimeofday(&bw->bwstart, NULL);
1033                 return;
1034         }
1035
1036         bw->lamt += read_len;
1037         if (bw->lamt < bw->thresh)
1038                 return;
1039
1040         gettimeofday(&bw->bwend, NULL);
1041         timersub(&bw->bwend, &bw->bwstart, &bw->bwend);
1042         if (!timerisset(&bw->bwend))
1043                 return;
1044
1045         bw->lamt *= 8;
1046         waitlen = (double)1000000L * bw->lamt / bw->rate;
1047
1048         bw->bwstart.tv_sec = waitlen / 1000000L;
1049         bw->bwstart.tv_usec = waitlen % 1000000L;
1050
1051         if (timercmp(&bw->bwstart, &bw->bwend, >)) {
1052                 timersub(&bw->bwstart, &bw->bwend, &bw->bwend);
1053
1054                 /* Adjust the wait time */
1055                 if (bw->bwend.tv_sec) {
1056                         bw->thresh /= 2;
1057                         if (bw->thresh < bw->buflen / 4)
1058                                 bw->thresh = bw->buflen / 4;
1059                 } else if (bw->bwend.tv_usec < 10000) {
1060                         bw->thresh *= 2;
1061                         if (bw->thresh > bw->buflen * 8)
1062                                 bw->thresh = bw->buflen * 8;
1063                 }
1064
1065                 TIMEVAL_TO_TIMESPEC(&bw->bwend, &ts);
1066                 while (nanosleep(&ts, &rm) == -1) {
1067                         if (errno != EINTR)
1068                                 break;
1069                         ts = rm;
1070                 }
1071         }
1072
1073         bw->lamt = 0;
1074         gettimeofday(&bw->bwstart, NULL);
1075 }
1076
1077 /* Make a template filename for mk[sd]temp() */
1078 void
1079 mktemp_proto(char *s, size_t len)
1080 {
1081         const char *tmpdir;
1082         int r;
1083
1084         if ((tmpdir = getenv("TMPDIR")) != NULL) {
1085                 r = snprintf(s, len, "%s/ssh-XXXXXXXXXXXX", tmpdir);
1086                 if (r > 0 && (size_t)r < len)
1087                         return;
1088         }
1089         r = snprintf(s, len, "/tmp/ssh-XXXXXXXXXXXX");
1090         if (r < 0 || (size_t)r >= len)
1091                 fatal("%s: template string too short", __func__);
1092 }
1093
1094 static const struct {
1095         const char *name;
1096         int value;
1097 } ipqos[] = {
1098         { "none", INT_MAX },            /* can't use 0 here; that's CS0 */
1099         { "af11", IPTOS_DSCP_AF11 },
1100         { "af12", IPTOS_DSCP_AF12 },
1101         { "af13", IPTOS_DSCP_AF13 },
1102         { "af21", IPTOS_DSCP_AF21 },
1103         { "af22", IPTOS_DSCP_AF22 },
1104         { "af23", IPTOS_DSCP_AF23 },
1105         { "af31", IPTOS_DSCP_AF31 },
1106         { "af32", IPTOS_DSCP_AF32 },
1107         { "af33", IPTOS_DSCP_AF33 },
1108         { "af41", IPTOS_DSCP_AF41 },
1109         { "af42", IPTOS_DSCP_AF42 },
1110         { "af43", IPTOS_DSCP_AF43 },
1111         { "cs0", IPTOS_DSCP_CS0 },
1112         { "cs1", IPTOS_DSCP_CS1 },
1113         { "cs2", IPTOS_DSCP_CS2 },
1114         { "cs3", IPTOS_DSCP_CS3 },
1115         { "cs4", IPTOS_DSCP_CS4 },
1116         { "cs5", IPTOS_DSCP_CS5 },
1117         { "cs6", IPTOS_DSCP_CS6 },
1118         { "cs7", IPTOS_DSCP_CS7 },
1119         { "ef", IPTOS_DSCP_EF },
1120         { "lowdelay", IPTOS_LOWDELAY },
1121         { "throughput", IPTOS_THROUGHPUT },
1122         { "reliability", IPTOS_RELIABILITY },
1123         { NULL, -1 }
1124 };
1125
1126 int
1127 parse_ipqos(const char *cp)
1128 {
1129         u_int i;
1130         char *ep;
1131         long val;
1132
1133         if (cp == NULL)
1134                 return -1;
1135         for (i = 0; ipqos[i].name != NULL; i++) {
1136                 if (strcasecmp(cp, ipqos[i].name) == 0)
1137                         return ipqos[i].value;
1138         }
1139         /* Try parsing as an integer */
1140         val = strtol(cp, &ep, 0);
1141         if (*cp == '\0' || *ep != '\0' || val < 0 || val > 255)
1142                 return -1;
1143         return val;
1144 }
1145
1146 const char *
1147 iptos2str(int iptos)
1148 {
1149         int i;
1150         static char iptos_str[sizeof "0xff"];
1151
1152         for (i = 0; ipqos[i].name != NULL; i++) {
1153                 if (ipqos[i].value == iptos)
1154                         return ipqos[i].name;
1155         }
1156         snprintf(iptos_str, sizeof iptos_str, "0x%02x", iptos);
1157         return iptos_str;
1158 }
1159
1160 void
1161 lowercase(char *s)
1162 {
1163         for (; *s; s++)
1164                 *s = tolower((u_char)*s);
1165 }
1166
1167 int
1168 unix_listener(const char *path, int backlog, int unlink_first)
1169 {
1170         struct sockaddr_un sunaddr;
1171         int saved_errno, sock;
1172
1173         memset(&sunaddr, 0, sizeof(sunaddr));
1174         sunaddr.sun_family = AF_UNIX;
1175         if (strlcpy(sunaddr.sun_path, path, sizeof(sunaddr.sun_path)) >= sizeof(sunaddr.sun_path)) {
1176                 error("%s: \"%s\" too long for Unix domain socket", __func__,
1177                     path);
1178                 errno = ENAMETOOLONG;
1179                 return -1;
1180         }
1181
1182         sock = socket(PF_UNIX, SOCK_STREAM, 0);
1183         if (sock < 0) {
1184                 saved_errno = errno;
1185                 error("socket: %.100s", strerror(errno));
1186                 errno = saved_errno;
1187                 return -1;
1188         }
1189         if (unlink_first == 1) {
1190                 if (unlink(path) != 0 && errno != ENOENT)
1191                         error("unlink(%s): %.100s", path, strerror(errno));
1192         }
1193         if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) {
1194                 saved_errno = errno;
1195                 error("bind: %.100s", strerror(errno));
1196                 close(sock);
1197                 error("%s: cannot bind to path: %s", __func__, path);
1198                 errno = saved_errno;
1199                 return -1;
1200         }
1201         if (listen(sock, backlog) < 0) {
1202                 saved_errno = errno;
1203                 error("listen: %.100s", strerror(errno));
1204                 close(sock);
1205                 unlink(path);
1206                 error("%s: cannot listen on path: %s", __func__, path);
1207                 errno = saved_errno;
1208                 return -1;
1209         }
1210         return sock;
1211 }
1212
1213 void
1214 sock_set_v6only(int s)
1215 {
1216 #if defined(IPV6_V6ONLY) && !defined(__OpenBSD__)
1217         int on = 1;
1218
1219         debug3("%s: set socket %d IPV6_V6ONLY", __func__, s);
1220         if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) == -1)
1221                 error("setsockopt IPV6_V6ONLY: %s", strerror(errno));
1222 #endif
1223 }
1224
1225 /*
1226  * Compares two strings that maybe be NULL. Returns non-zero if strings
1227  * are both NULL or are identical, returns zero otherwise.
1228  */
1229 static int
1230 strcmp_maybe_null(const char *a, const char *b)
1231 {
1232         if ((a == NULL && b != NULL) || (a != NULL && b == NULL))
1233                 return 0;
1234         if (a != NULL && strcmp(a, b) != 0)
1235                 return 0;
1236         return 1;
1237 }
1238
1239 /*
1240  * Compare two forwards, returning non-zero if they are identical or
1241  * zero otherwise.
1242  */
1243 int
1244 forward_equals(const struct Forward *a, const struct Forward *b)
1245 {
1246         if (strcmp_maybe_null(a->listen_host, b->listen_host) == 0)
1247                 return 0;
1248         if (a->listen_port != b->listen_port)
1249                 return 0;
1250         if (strcmp_maybe_null(a->listen_path, b->listen_path) == 0)
1251                 return 0;
1252         if (strcmp_maybe_null(a->connect_host, b->connect_host) == 0)
1253                 return 0;
1254         if (a->connect_port != b->connect_port)
1255                 return 0;
1256         if (strcmp_maybe_null(a->connect_path, b->connect_path) == 0)
1257                 return 0;
1258         /* allocated_port and handle are not checked */
1259         return 1;
1260 }
1261
1262 /* returns 1 if bind to specified port by specified user is permitted */
1263 int
1264 bind_permitted(int port, uid_t uid)
1265 {
1266         if (port < IPPORT_RESERVED && uid != 0)
1267                 return 0;
1268         return 1;
1269 }
1270
1271 /* returns 1 if process is already daemonized, 0 otherwise */
1272 int
1273 daemonized(void)
1274 {
1275         int fd;
1276
1277         if ((fd = open(_PATH_TTY, O_RDONLY | O_NOCTTY)) >= 0) {
1278                 close(fd);
1279                 return 0;       /* have controlling terminal */
1280         }
1281         if (getppid() != 1)
1282                 return 0;       /* parent is not init */
1283         if (getsid(0) != getpid())
1284                 return 0;       /* not session leader */
1285         debug3("already daemonized");
1286         return 1;
1287 }
1288
1289
1290 /*
1291  * Splits 's' into an argument vector. Handles quoted string and basic
1292  * escape characters (\\, \", \'). Caller must free the argument vector
1293  * and its members.
1294  */
1295 int
1296 argv_split(const char *s, int *argcp, char ***argvp)
1297 {
1298         int r = SSH_ERR_INTERNAL_ERROR;
1299         int argc = 0, quote, i, j;
1300         char *arg, **argv = xcalloc(1, sizeof(*argv));
1301
1302         *argvp = NULL;
1303         *argcp = 0;
1304
1305         for (i = 0; s[i] != '\0'; i++) {
1306                 /* Skip leading whitespace */
1307                 if (s[i] == ' ' || s[i] == '\t')
1308                         continue;
1309
1310                 /* Start of a token */
1311                 quote = 0;
1312                 if (s[i] == '\\' &&
1313                     (s[i + 1] == '\'' || s[i + 1] == '\"' || s[i + 1] == '\\'))
1314                         i++;
1315                 else if (s[i] == '\'' || s[i] == '"')
1316                         quote = s[i++];
1317
1318                 argv = xreallocarray(argv, (argc + 2), sizeof(*argv));
1319                 arg = argv[argc++] = xcalloc(1, strlen(s + i) + 1);
1320                 argv[argc] = NULL;
1321
1322                 /* Copy the token in, removing escapes */
1323                 for (j = 0; s[i] != '\0'; i++) {
1324                         if (s[i] == '\\') {
1325                                 if (s[i + 1] == '\'' ||
1326                                     s[i + 1] == '\"' ||
1327                                     s[i + 1] == '\\') {
1328                                         i++; /* Skip '\' */
1329                                         arg[j++] = s[i];
1330                                 } else {
1331                                         /* Unrecognised escape */
1332                                         arg[j++] = s[i];
1333                                 }
1334                         } else if (quote == 0 && (s[i] == ' ' || s[i] == '\t'))
1335                                 break; /* done */
1336                         else if (quote != 0 && s[i] == quote)
1337                                 break; /* done */
1338                         else
1339                                 arg[j++] = s[i];
1340                 }
1341                 if (s[i] == '\0') {
1342                         if (quote != 0) {
1343                                 /* Ran out of string looking for close quote */
1344                                 r = SSH_ERR_INVALID_FORMAT;
1345                                 goto out;
1346                         }
1347                         break;
1348                 }
1349         }
1350         /* Success */
1351         *argcp = argc;
1352         *argvp = argv;
1353         argc = 0;
1354         argv = NULL;
1355         r = 0;
1356  out:
1357         if (argc != 0 && argv != NULL) {
1358                 for (i = 0; i < argc; i++)
1359                         free(argv[i]);
1360                 free(argv);
1361         }
1362         return r;
1363 }
1364
1365 /*
1366  * Reassemble an argument vector into a string, quoting and escaping as
1367  * necessary. Caller must free returned string.
1368  */
1369 char *
1370 argv_assemble(int argc, char **argv)
1371 {
1372         int i, j, ws, r;
1373         char c, *ret;
1374         struct sshbuf *buf, *arg;
1375
1376         if ((buf = sshbuf_new()) == NULL || (arg = sshbuf_new()) == NULL)
1377                 fatal("%s: sshbuf_new failed", __func__);
1378
1379         for (i = 0; i < argc; i++) {
1380                 ws = 0;
1381                 sshbuf_reset(arg);
1382                 for (j = 0; argv[i][j] != '\0'; j++) {
1383                         r = 0;
1384                         c = argv[i][j];
1385                         switch (c) {
1386                         case ' ':
1387                         case '\t':
1388                                 ws = 1;
1389                                 r = sshbuf_put_u8(arg, c);
1390                                 break;
1391                         case '\\':
1392                         case '\'':
1393                         case '"':
1394                                 if ((r = sshbuf_put_u8(arg, '\\')) != 0)
1395                                         break;
1396                                 /* FALLTHROUGH */
1397                         default:
1398                                 r = sshbuf_put_u8(arg, c);
1399                                 break;
1400                         }
1401                         if (r != 0)
1402                                 fatal("%s: sshbuf_put_u8: %s",
1403                                     __func__, ssh_err(r));
1404                 }
1405                 if ((i != 0 && (r = sshbuf_put_u8(buf, ' ')) != 0) ||
1406                     (ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0) ||
1407                     (r = sshbuf_putb(buf, arg)) != 0 ||
1408                     (ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0))
1409                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
1410         }
1411         if ((ret = malloc(sshbuf_len(buf) + 1)) == NULL)
1412                 fatal("%s: malloc failed", __func__);
1413         memcpy(ret, sshbuf_ptr(buf), sshbuf_len(buf));
1414         ret[sshbuf_len(buf)] = '\0';
1415         sshbuf_free(buf);
1416         sshbuf_free(arg);
1417         return ret;
1418 }
1419
1420 /*
1421  * Runs command in a subprocess wuth a minimal environment.
1422  * Returns pid on success, 0 on failure.
1423  * The child stdout and stderr maybe captured, left attached or sent to
1424  * /dev/null depending on the contents of flags.
1425  * "tag" is prepended to log messages.
1426  * NB. "command" is only used for logging; the actual command executed is
1427  * av[0].
1428  */
1429 pid_t
1430 subprocess(const char *tag, struct passwd *pw, const char *command,
1431     int ac, char **av, FILE **child, u_int flags)
1432 {
1433         FILE *f = NULL;
1434         struct stat st;
1435         int fd, devnull, p[2], i;
1436         pid_t pid;
1437         char *cp, errmsg[512];
1438         u_int envsize;
1439         char **child_env;
1440
1441         if (child != NULL)
1442                 *child = NULL;
1443
1444         debug3("%s: %s command \"%s\" running as %s (flags 0x%x)", __func__,
1445             tag, command, pw->pw_name, flags);
1446
1447         /* Check consistency */
1448         if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
1449             (flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) {
1450                 error("%s: inconsistent flags", __func__);
1451                 return 0;
1452         }
1453         if (((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) != (child == NULL)) {
1454                 error("%s: inconsistent flags/output", __func__);
1455                 return 0;
1456         }
1457
1458         /*
1459          * If executing an explicit binary, then verify the it exists
1460          * and appears safe-ish to execute
1461          */
1462         if (*av[0] != '/') {
1463                 error("%s path is not absolute", tag);
1464                 return 0;
1465         }
1466         temporarily_use_uid(pw);
1467         if (stat(av[0], &st) < 0) {
1468                 error("Could not stat %s \"%s\": %s", tag,
1469                     av[0], strerror(errno));
1470                 restore_uid();
1471                 return 0;
1472         }
1473         if (safe_path(av[0], &st, NULL, 0, errmsg, sizeof(errmsg)) != 0) {
1474                 error("Unsafe %s \"%s\": %s", tag, av[0], errmsg);
1475                 restore_uid();
1476                 return 0;
1477         }
1478         /* Prepare to keep the child's stdout if requested */
1479         if (pipe(p) != 0) {
1480                 error("%s: pipe: %s", tag, strerror(errno));
1481                 restore_uid();
1482                 return 0;
1483         }
1484         restore_uid();
1485
1486         switch ((pid = fork())) {
1487         case -1: /* error */
1488                 error("%s: fork: %s", tag, strerror(errno));
1489                 close(p[0]);
1490                 close(p[1]);
1491                 return 0;
1492         case 0: /* child */
1493                 /* Prepare a minimal environment for the child. */
1494                 envsize = 5;
1495                 child_env = xcalloc(sizeof(*child_env), envsize);
1496                 child_set_env(&child_env, &envsize, "PATH", _PATH_STDPATH);
1497                 child_set_env(&child_env, &envsize, "USER", pw->pw_name);
1498                 child_set_env(&child_env, &envsize, "LOGNAME", pw->pw_name);
1499                 child_set_env(&child_env, &envsize, "HOME", pw->pw_dir);
1500                 if ((cp = getenv("LANG")) != NULL)
1501                         child_set_env(&child_env, &envsize, "LANG", cp);
1502
1503                 for (i = 0; i < NSIG; i++)
1504                         signal(i, SIG_DFL);
1505
1506                 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1507                         error("%s: open %s: %s", tag, _PATH_DEVNULL,
1508                             strerror(errno));
1509                         _exit(1);
1510                 }
1511                 if (dup2(devnull, STDIN_FILENO) == -1) {
1512                         error("%s: dup2: %s", tag, strerror(errno));
1513                         _exit(1);
1514                 }
1515
1516                 /* Set up stdout as requested; leave stderr in place for now. */
1517                 fd = -1;
1518                 if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0)
1519                         fd = p[1];
1520                 else if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0)
1521                         fd = devnull;
1522                 if (fd != -1 && dup2(fd, STDOUT_FILENO) == -1) {
1523                         error("%s: dup2: %s", tag, strerror(errno));
1524                         _exit(1);
1525                 }
1526                 closefrom(STDERR_FILENO + 1);
1527
1528                 /* Don't use permanently_set_uid() here to avoid fatal() */
1529                 if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
1530                         error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid,
1531                             strerror(errno));
1532                         _exit(1);
1533                 }
1534                 if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) {
1535                         error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid,
1536                             strerror(errno));
1537                         _exit(1);
1538                 }
1539                 /* stdin is pointed to /dev/null at this point */
1540                 if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
1541                     dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
1542                         error("%s: dup2: %s", tag, strerror(errno));
1543                         _exit(1);
1544                 }
1545
1546                 execve(av[0], av, child_env);
1547                 error("%s exec \"%s\": %s", tag, command, strerror(errno));
1548                 _exit(127);
1549         default: /* parent */
1550                 break;
1551         }
1552
1553         close(p[1]);
1554         if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0)
1555                 close(p[0]);
1556         else if ((f = fdopen(p[0], "r")) == NULL) {
1557                 error("%s: fdopen: %s", tag, strerror(errno));
1558                 close(p[0]);
1559                 /* Don't leave zombie child */
1560                 kill(pid, SIGTERM);
1561                 while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
1562                         ;
1563                 return 0;
1564         }
1565         /* Success */
1566         debug3("%s: %s pid %ld", __func__, tag, (long)pid);
1567         if (child != NULL)
1568                 *child = f;
1569         return pid;
1570 }
1571
1572 /* Returns 0 if pid exited cleanly, non-zero otherwise */
1573 int
1574 exited_cleanly(pid_t pid, const char *tag, const char *cmd, int quiet)
1575 {
1576         int status;
1577
1578         while (waitpid(pid, &status, 0) == -1) {
1579                 if (errno != EINTR) {
1580                         error("%s: waitpid: %s", tag, strerror(errno));
1581                         return -1;
1582                 }
1583         }
1584         if (WIFSIGNALED(status)) {
1585                 error("%s %s exited on signal %d", tag, cmd, WTERMSIG(status));
1586                 return -1;
1587         } else if (WEXITSTATUS(status) != 0) {
1588                 do_log2(quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_INFO,
1589                     "%s %s failed, status %d", tag, cmd, WEXITSTATUS(status));
1590                 return -1;
1591         }
1592         return 0;
1593 }
1594
1595 /*
1596  * Check a given path for security. This is defined as all components
1597  * of the path to the file must be owned by either the owner of
1598  * of the file or root and no directories must be group or world writable.
1599  *
1600  * XXX Should any specific check be done for sym links ?
1601  *
1602  * Takes a file name, its stat information (preferably from fstat() to
1603  * avoid races), the uid of the expected owner, their home directory and an
1604  * error buffer plus max size as arguments.
1605  *
1606  * Returns 0 on success and -1 on failure
1607  */
1608 int
1609 safe_path(const char *name, struct stat *stp, const char *pw_dir,
1610     uid_t uid, char *err, size_t errlen)
1611 {
1612         char buf[PATH_MAX], homedir[PATH_MAX];
1613         char *cp;
1614         int comparehome = 0;
1615         struct stat st;
1616
1617         if (realpath(name, buf) == NULL) {
1618                 snprintf(err, errlen, "realpath %s failed: %s", name,
1619                     strerror(errno));
1620                 return -1;
1621         }
1622         if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
1623                 comparehome = 1;
1624
1625         if (!S_ISREG(stp->st_mode)) {
1626                 snprintf(err, errlen, "%s is not a regular file", buf);
1627                 return -1;
1628         }
1629         if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
1630             (stp->st_mode & 022) != 0) {
1631                 snprintf(err, errlen, "bad ownership or modes for file %s",
1632                     buf);
1633                 return -1;
1634         }
1635
1636         /* for each component of the canonical path, walking upwards */
1637         for (;;) {
1638                 if ((cp = dirname(buf)) == NULL) {
1639                         snprintf(err, errlen, "dirname() failed");
1640                         return -1;
1641                 }
1642                 strlcpy(buf, cp, sizeof(buf));
1643
1644                 if (stat(buf, &st) < 0 ||
1645                     (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
1646                     (st.st_mode & 022) != 0) {
1647                         snprintf(err, errlen,
1648                             "bad ownership or modes for directory %s", buf);
1649                         return -1;
1650                 }
1651
1652                 /* If are past the homedir then we can stop */
1653                 if (comparehome && strcmp(homedir, buf) == 0)
1654                         break;
1655
1656                 /*
1657                  * dirname should always complete with a "/" path,
1658                  * but we can be paranoid and check for "." too
1659                  */
1660                 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
1661                         break;
1662         }
1663         return 0;
1664 }
1665
1666 /*
1667  * Version of safe_path() that accepts an open file descriptor to
1668  * avoid races.
1669  *
1670  * Returns 0 on success and -1 on failure
1671  */
1672 int
1673 safe_path_fd(int fd, const char *file, struct passwd *pw,
1674     char *err, size_t errlen)
1675 {
1676         struct stat st;
1677
1678         /* check the open file to avoid races */
1679         if (fstat(fd, &st) < 0) {
1680                 snprintf(err, errlen, "cannot stat file %s: %s",
1681                     file, strerror(errno));
1682                 return -1;
1683         }
1684         return safe_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
1685 }
1686
1687 /*
1688  * Sets the value of the given variable in the environment.  If the variable
1689  * already exists, its value is overridden.
1690  */
1691 void
1692 child_set_env(char ***envp, u_int *envsizep, const char *name,
1693         const char *value)
1694 {
1695         char **env;
1696         u_int envsize;
1697         u_int i, namelen;
1698
1699         if (strchr(name, '=') != NULL) {
1700                 error("Invalid environment variable \"%.100s\"", name);
1701                 return;
1702         }
1703
1704         /*
1705          * If we're passed an uninitialized list, allocate a single null
1706          * entry before continuing.
1707          */
1708         if (*envp == NULL && *envsizep == 0) {
1709                 *envp = xmalloc(sizeof(char *));
1710                 *envp[0] = NULL;
1711                 *envsizep = 1;
1712         }
1713
1714         /*
1715          * Find the slot where the value should be stored.  If the variable
1716          * already exists, we reuse the slot; otherwise we append a new slot
1717          * at the end of the array, expanding if necessary.
1718          */
1719         env = *envp;
1720         namelen = strlen(name);
1721         for (i = 0; env[i]; i++)
1722                 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
1723                         break;
1724         if (env[i]) {
1725                 /* Reuse the slot. */
1726                 free(env[i]);
1727         } else {
1728                 /* New variable.  Expand if necessary. */
1729                 envsize = *envsizep;
1730                 if (i >= envsize - 1) {
1731                         if (envsize >= 1000)
1732                                 fatal("child_set_env: too many env vars");
1733                         envsize += 50;
1734                         env = (*envp) = xreallocarray(env, envsize, sizeof(char *));
1735                         *envsizep = envsize;
1736                 }
1737                 /* Need to set the NULL pointer at end of array beyond the new slot. */
1738                 env[i + 1] = NULL;
1739         }
1740
1741         /* Allocate space and format the variable in the appropriate slot. */
1742         env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
1743         snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
1744 }
1745