auth-options.c

   1 /* $OpenBSD: auth-options.c,v 1.42 2008/05/08 12:02:23 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * As far as I am concerned, the code I have written for this software
   7  * can be used freely for any purpose.  Any derived versions of this
   8  * software must be clearly marked as such, and if the derived work is
   9  * incompatible with the protocol description in the RFC file, it must be
  10  * called by a name other than "ssh" or "Secure Shell".
  11  */
  12
  13 #include "includes.h"
  14
  15 #include <sys/types.h>
  16
  17 #include <netdb.h>
  18 #include <pwd.h>
  19 #include <string.h>
  20 #include <stdio.h>
  21 #include <stdarg.h>
  22
  23 #include "openbsd-compat/sys-queue.h"
  24 #include "xmalloc.h"
  25 #include "match.h"
  26 #include "log.h"
  27 #include "canohost.h"
  28 #include "buffer.h"
  29 #include "channels.h"
  30 #include "auth-options.h"
  31 #include "servconf.h"
  32 #include "misc.h"
  33 #include "key.h"
  34 #include "hostfile.h"
  35 #include "auth.h"
  36 #ifdef GSSAPI
  37 #include "ssh-gss.h"
  38 #endif
  39 #include "monitor_wrap.h"
  40
  41 /* Flags set authorized_keys flags */
  42 int no_port_forwarding_flag = 0;
  43 int no_agent_forwarding_flag = 0;
  44 int no_x11_forwarding_flag = 0;
  45 int no_pty_flag = 0;
  46 int no_user_rc = 0;
  47
  48 /* "command=" option. */
  49 char *forced_command = NULL;
  50
  51 /* "environment=" options. */
  52 struct envstring *custom_environment = NULL;
  53
  54 /* "tunnel=" option. */
  55 int forced_tun_device = -1;
  56
  57 extern ServerOptions options;
  58
  59 void
  60 auth_clear_options(void)
  61 {
  62         no_agent_forwarding_flag = 0;
  63         no_port_forwarding_flag = 0;
  64         no_pty_flag = 0;
  65         no_x11_forwarding_flag = 0;
  66         no_user_rc = 0;
  67         while (custom_environment) {
  68                 struct envstring *ce = custom_environment;
  69                 custom_environment = ce->next;
  70                 xfree(ce->s);
  71                 xfree(ce);
  72         }
  73         if (forced_command) {
  74                 xfree(forced_command);
  75                 forced_command = NULL;
  76         }
  77         forced_tun_device = -1;
  78         channel_clear_permitted_opens();
  79         auth_debug_reset();
  80 }
  81
  82 /*
  83  * return 1 if access is granted, 0 if not.
  84  * side effect: sets key option flags
  85  */
  86 int
  87 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
  88 {
  89         const char *cp;
  90         int i;
  91
  92         /* reset options */
  93         auth_clear_options();
  94
  95         if (!opts)
  96                 return 1;
  97
  98         while (*opts && *opts != ' ' && *opts != '\t') {
  99                 cp = "no-port-forwarding";
 100                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 101                         auth_debug_add("Port forwarding disabled.");
 102                         no_port_forwarding_flag = 1;
 103                         opts += strlen(cp);
 104                         goto next_option;
 105                 }
 106                 cp = "no-agent-forwarding";
 107                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 108                         auth_debug_add("Agent forwarding disabled.");
 109                         no_agent_forwarding_flag = 1;
 110                         opts += strlen(cp);
 111                         goto next_option;
 112                 }
 113                 cp = "no-X11-forwarding";
 114                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 115                         auth_debug_add("X11 forwarding disabled.");
 116                         no_x11_forwarding_flag = 1;
 117                         opts += strlen(cp);
 118                         goto next_option;
 119                 }
 120                 cp = "no-pty";
 121                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 122                         auth_debug_add("Pty allocation disabled.");
 123                         no_pty_flag = 1;
 124                         opts += strlen(cp);
 125                         goto next_option;
 126                 }
 127                 cp = "no-user-rc";
 128                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 129                         auth_debug_add("User rc file execution disabled.");
 130                         no_user_rc = 1;
 131                         opts += strlen(cp);
 132                         goto next_option;
 133                 }
 134                 cp = "command=\"";
 135                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 136                         opts += strlen(cp);
 137                         forced_command = xmalloc(strlen(opts) + 1);
 138                         i = 0;
 139                         while (*opts) {
 140                                 if (*opts == '"')
 141                                         break;
 142                                 if (*opts == '\\' && opts[1] == '"') {
 143                                         opts += 2;
 144                                         forced_command[i++] = '"';
 145                                         continue;
 146                                 }
 147                                 forced_command[i++] = *opts++;
 148                         }
 149                         if (!*opts) {
 150                                 debug("%.100s, line %lu: missing end quote",
 151                                     file, linenum);
 152                                 auth_debug_add("%.100s, line %lu: missing end quote",
 153                                     file, linenum);
 154                                 xfree(forced_command);
 155                                 forced_command = NULL;
 156                                 goto bad_option;
 157                         }
 158                         forced_command[i] = '\0';
 159                         auth_debug_add("Forced command: %.900s", forced_command);
 160                         opts++;
 161                         goto next_option;
 162                 }
 163                 cp = "environment=\"";
 164                 if (options.permit_user_env &&
 165                     strncasecmp(opts, cp, strlen(cp)) == 0) {
 166                         char *s;
 167                         struct envstring *new_envstring;
 168
 169                         opts += strlen(cp);
 170                         s = xmalloc(strlen(opts) + 1);
 171                         i = 0;
 172                         while (*opts) {
 173                                 if (*opts == '"')
 174                                         break;
 175                                 if (*opts == '\\' && opts[1] == '"') {
 176                                         opts += 2;
 177                                         s[i++] = '"';
 178                                         continue;
 179                                 }
 180                                 s[i++] = *opts++;
 181                         }
 182                         if (!*opts) {
 183                                 debug("%.100s, line %lu: missing end quote",
 184                                     file, linenum);
 185                                 auth_debug_add("%.100s, line %lu: missing end quote",
 186                                     file, linenum);
 187                                 xfree(s);
 188                                 goto bad_option;
 189                         }
 190                         s[i] = '\0';
 191                         auth_debug_add("Adding to environment: %.900s", s);
 192                         debug("Adding to environment: %.900s", s);
 193                         opts++;
 194                         new_envstring = xmalloc(sizeof(struct envstring));
 195                         new_envstring->s = s;
 196                         new_envstring->next = custom_environment;
 197                         custom_environment = new_envstring;
 198                         goto next_option;
 199                 }
 200                 cp = "from=\"";
 201                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 202                         const char *remote_ip = get_remote_ipaddr();
 203                         const char *remote_host = get_canonical_hostname(
 204                             options.use_dns);
 205                         char *patterns = xmalloc(strlen(opts) + 1);
 206
 207                         opts += strlen(cp);
 208                         i = 0;
 209                         while (*opts) {
 210                                 if (*opts == '"')
 211                                         break;
 212                                 if (*opts == '\\' && opts[1] == '"') {
 213                                         opts += 2;
 214                                         patterns[i++] = '"';
 215                                         continue;
 216                                 }
 217                                 patterns[i++] = *opts++;
 218                         }
 219                         if (!*opts) {
 220                                 debug("%.100s, line %lu: missing end quote",
 221                                     file, linenum);
 222                                 auth_debug_add("%.100s, line %lu: missing end quote",
 223                                     file, linenum);
 224                                 xfree(patterns);
 225                                 goto bad_option;
 226                         }
 227                         patterns[i] = '\0';
 228                         opts++;
 229                         if (match_host_and_ip(remote_host, remote_ip,
 230                             patterns) != 1) {
 231                                 xfree(patterns);
 232                                 logit("Authentication tried for %.100s with "
 233                                     "correct key but not from a permitted "
 234                                     "host (host=%.200s, ip=%.200s).",
 235                                     pw->pw_name, remote_host, remote_ip);
 236                                 auth_debug_add("Your host '%.200s' is not "
 237                                     "permitted to use this key for login.",
 238                                     remote_host);
 239                                 /* deny access */
 240                                 return 0;
 241                         }
 242                         xfree(patterns);
 243                         /* Host name matches. */
 244                         goto next_option;
 245                 }
 246                 cp = "permitopen=\"";
 247                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 248                         char *host, *p;
 249                         u_short port;
 250                         char *patterns = xmalloc(strlen(opts) + 1);
 251
 252                         opts += strlen(cp);
 253                         i = 0;
 254                         while (*opts) {
 255                                 if (*opts == '"')
 256                                         break;
 257                                 if (*opts == '\\' && opts[1] == '"') {
 258                                         opts += 2;
 259                                         patterns[i++] = '"';
 260                                         continue;
 261                                 }
 262                                 patterns[i++] = *opts++;
 263                         }
 264                         if (!*opts) {
 265                                 debug("%.100s, line %lu: missing end quote",
 266                                     file, linenum);
 267                                 auth_debug_add("%.100s, line %lu: missing "
 268                                     "end quote", file, linenum);
 269                                 xfree(patterns);
 270                                 goto bad_option;
 271                         }
 272                         patterns[i] = '\0';
 273                         opts++;
 274                         p = patterns;
 275                         host = hpdelim(&p);
 276                         if (host == NULL || strlen(host) >= NI_MAXHOST) {
 277                                 debug("%.100s, line %lu: Bad permitopen "
 278                                     "specification <%.100s>", file, linenum,
 279                                     patterns);
 280                                 auth_debug_add("%.100s, line %lu: "
 281                                     "Bad permitopen specification", file,
 282                                     linenum);
 283                                 xfree(patterns);
 284                                 goto bad_option;
 285                         }
 286                         host = cleanhostname(host);
 287                         if (p == NULL || (port = a2port(p)) == 0) {
 288                                 debug("%.100s, line %lu: Bad permitopen port "
 289                                     "<%.100s>", file, linenum, p ? p : "");
 290                                 auth_debug_add("%.100s, line %lu: "
 291                                     "Bad permitopen port", file, linenum);
 292                                 xfree(patterns);
 293                                 goto bad_option;
 294                         }
 295                         if (options.allow_tcp_forwarding)
 296                                 channel_add_permitted_opens(host, port);
 297                         xfree(patterns);
 298                         goto next_option;
 299                 }
 300                 cp = "tunnel=\"";
 301                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 302                         char *tun = NULL;
 303                         opts += strlen(cp);
 304                         tun = xmalloc(strlen(opts) + 1);
 305                         i = 0;
 306                         while (*opts) {
 307                                 if (*opts == '"')
 308                                         break;
 309                                 tun[i++] = *opts++;
 310                         }
 311                         if (!*opts) {
 312                                 debug("%.100s, line %lu: missing end quote",
 313                                     file, linenum);
 314                                 auth_debug_add("%.100s, line %lu: missing end quote",
 315                                     file, linenum);
 316                                 xfree(tun);
 317                                 forced_tun_device = -1;
 318                                 goto bad_option;
 319                         }
 320                         tun[i] = '\0';
 321                         forced_tun_device = a2tun(tun, NULL);
 322                         xfree(tun);
 323                         if (forced_tun_device == SSH_TUNID_ERR) {
 324                                 debug("%.100s, line %lu: invalid tun device",
 325                                     file, linenum);
 326                                 auth_debug_add("%.100s, line %lu: invalid tun device",
 327                                     file, linenum);
 328                                 forced_tun_device = -1;
 329                                 goto bad_option;
 330                         }
 331                         auth_debug_add("Forced tun device: %d", forced_tun_device);
 332                         opts++;
 333                         goto next_option;
 334                 }
 335 next_option:
 336                 /*
 337                  * Skip the comma, and move to the next option
 338                  * (or break out if there are no more).
 339                  */
 340                 if (!*opts)
 341                         fatal("Bugs in auth-options.c option processing.");
 342                 if (*opts == ' ' || *opts == '\t')
 343                         break;          /* End of options. */
 344                 if (*opts != ',')
 345                         goto bad_option;
 346                 opts++;
 347                 /* Process the next option. */
 348         }
 349
 350         if (!use_privsep)
 351                 auth_debug_send();
 352
 353         /* grant access */
 354         return 1;
 355
 356 bad_option:
 357         logit("Bad options in %.100s file, line %lu: %.50s",
 358             file, linenum, opts);
 359         auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
 360             file, linenum, opts);
 361
 362         if (!use_privsep)
 363                 auth_debug_send();
 364
 365         /* deny access */
 366         return 0;
 367 }