crypto/openssh-5/auth-options.c

   1 /* $OpenBSD: auth-options.c,v 1.41 2008/03/26 21:28:14 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 "xmalloc.h"
  24 #include "match.h"
  25 #include "log.h"
  26 #include "canohost.h"
  27 #include "buffer.h"
  28 #include "channels.h"
  29 #include "auth-options.h"
  30 #include "servconf.h"
  31 #include "misc.h"
  32 #include "key.h"
  33 #include "hostfile.h"
  34 #include "auth.h"
  35 #ifdef GSSAPI
  36 #include "ssh-gss.h"
  37 #endif
  38 #include "monitor_wrap.h"
  39
  40 /* Flags set authorized_keys flags */
  41 int no_port_forwarding_flag = 0;
  42 int no_agent_forwarding_flag = 0;
  43 int no_x11_forwarding_flag = 0;
  44 int no_pty_flag = 0;
  45 int no_user_rc = 0;
  46
  47 /* "command=" option. */
  48 char *forced_command = NULL;
  49
  50 /* "environment=" options. */
  51 struct envstring *custom_environment = NULL;
  52
  53 /* "tunnel=" option. */
  54 int forced_tun_device = -1;
  55
  56 extern ServerOptions options;
  57
  58 void
  59 auth_clear_options(void)
  60 {
  61         no_agent_forwarding_flag = 0;
  62         no_port_forwarding_flag = 0;
  63         no_pty_flag = 0;
  64         no_x11_forwarding_flag = 0;
  65         no_user_rc = 0;
  66         while (custom_environment) {
  67                 struct envstring *ce = custom_environment;
  68                 custom_environment = ce->next;
  69                 xfree(ce->s);
  70                 xfree(ce);
  71         }
  72         if (forced_command) {
  73                 xfree(forced_command);
  74                 forced_command = NULL;
  75         }
  76         forced_tun_device = -1;
  77         channel_clear_permitted_opens();
  78         auth_debug_reset();
  79 }
  80
  81 /*
  82  * return 1 if access is granted, 0 if not.
  83  * side effect: sets key option flags
  84  */
  85 int
  86 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
  87 {
  88         const char *cp;
  89         int i;
  90
  91         /* reset options */
  92         auth_clear_options();
  93
  94         if (!opts)
  95                 return 1;
  96
  97         while (*opts && *opts != ' ' && *opts != '\t') {
  98                 cp = "no-port-forwarding";
  99                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 100                         auth_debug_add("Port forwarding disabled.");
 101                         no_port_forwarding_flag = 1;
 102                         opts += strlen(cp);
 103                         goto next_option;
 104                 }
 105                 cp = "no-agent-forwarding";
 106                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 107                         auth_debug_add("Agent forwarding disabled.");
 108                         no_agent_forwarding_flag = 1;
 109                         opts += strlen(cp);
 110                         goto next_option;
 111                 }
 112                 cp = "no-X11-forwarding";
 113                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 114                         auth_debug_add("X11 forwarding disabled.");
 115                         no_x11_forwarding_flag = 1;
 116                         opts += strlen(cp);
 117                         goto next_option;
 118                 }
 119                 cp = "no-pty";
 120                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 121                         auth_debug_add("Pty allocation disabled.");
 122                         no_pty_flag = 1;
 123                         opts += strlen(cp);
 124                         goto next_option;
 125                 }
 126                 cp = "no-user-rc";
 127                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 128                         auth_debug_add("User rc file execution disabled.");
 129                         no_user_rc = 1;
 130                         opts += strlen(cp);
 131                         goto next_option;
 132                 }
 133                 cp = "command=\"";
 134                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 135                         opts += strlen(cp);
 136                         forced_command = xmalloc(strlen(opts) + 1);
 137                         i = 0;
 138                         while (*opts) {
 139                                 if (*opts == '"')
 140                                         break;
 141                                 if (*opts == '\\' && opts[1] == '"') {
 142                                         opts += 2;
 143                                         forced_command[i++] = '"';
 144                                         continue;
 145                                 }
 146                                 forced_command[i++] = *opts++;
 147                         }
 148                         if (!*opts) {
 149                                 debug("%.100s, line %lu: missing end quote",
 150                                     file, linenum);
 151                                 auth_debug_add("%.100s, line %lu: missing end quote",
 152                                     file, linenum);
 153                                 xfree(forced_command);
 154                                 forced_command = NULL;
 155                                 goto bad_option;
 156                         }
 157                         forced_command[i] = '\0';
 158                         auth_debug_add("Forced command: %.900s", forced_command);
 159                         opts++;
 160                         goto next_option;
 161                 }
 162                 cp = "environment=\"";
 163                 if (options.permit_user_env &&
 164                     strncasecmp(opts, cp, strlen(cp)) == 0) {
 165                         char *s;
 166                         struct envstring *new_envstring;
 167
 168                         opts += strlen(cp);
 169                         s = xmalloc(strlen(opts) + 1);
 170                         i = 0;
 171                         while (*opts) {
 172                                 if (*opts == '"')
 173                                         break;
 174                                 if (*opts == '\\' && opts[1] == '"') {
 175                                         opts += 2;
 176                                         s[i++] = '"';
 177                                         continue;
 178                                 }
 179                                 s[i++] = *opts++;
 180                         }
 181                         if (!*opts) {
 182                                 debug("%.100s, line %lu: missing end quote",
 183                                     file, linenum);
 184                                 auth_debug_add("%.100s, line %lu: missing end quote",
 185                                     file, linenum);
 186                                 xfree(s);
 187                                 goto bad_option;
 188                         }
 189                         s[i] = '\0';
 190                         auth_debug_add("Adding to environment: %.900s", s);
 191                         debug("Adding to environment: %.900s", s);
 192                         opts++;
 193                         new_envstring = xmalloc(sizeof(struct envstring));
 194                         new_envstring->s = s;
 195                         new_envstring->next = custom_environment;
 196                         custom_environment = new_envstring;
 197                         goto next_option;
 198                 }
 199                 cp = "from=\"";
 200                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 201                         const char *remote_ip = get_remote_ipaddr();
 202                         const char *remote_host = get_canonical_hostname(
 203                             options.use_dns);
 204                         char *patterns = xmalloc(strlen(opts) + 1);
 205
 206                         opts += strlen(cp);
 207                         i = 0;
 208                         while (*opts) {
 209                                 if (*opts == '"')
 210                                         break;
 211                                 if (*opts == '\\' && opts[1] == '"') {
 212                                         opts += 2;
 213                                         patterns[i++] = '"';
 214                                         continue;
 215                                 }
 216                                 patterns[i++] = *opts++;
 217                         }
 218                         if (!*opts) {
 219                                 debug("%.100s, line %lu: missing end quote",
 220                                     file, linenum);
 221                                 auth_debug_add("%.100s, line %lu: missing end quote",
 222                                     file, linenum);
 223                                 xfree(patterns);
 224                                 goto bad_option;
 225                         }
 226                         patterns[i] = '\0';
 227                         opts++;
 228                         if (match_host_and_ip(remote_host, remote_ip,
 229                             patterns) != 1) {
 230                                 xfree(patterns);
 231                                 logit("Authentication tried for %.100s with "
 232                                     "correct key but not from a permitted "
 233                                     "host (host=%.200s, ip=%.200s).",
 234                                     pw->pw_name, remote_host, remote_ip);
 235                                 auth_debug_add("Your host '%.200s' is not "
 236                                     "permitted to use this key for login.",
 237                                     remote_host);
 238                                 /* deny access */
 239                                 return 0;
 240                         }
 241                         xfree(patterns);
 242                         /* Host name matches. */
 243                         goto next_option;
 244                 }
 245                 cp = "permitopen=\"";
 246                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 247                         char *host, *p;
 248                         u_short port;
 249                         char *patterns = xmalloc(strlen(opts) + 1);
 250
 251                         opts += strlen(cp);
 252                         i = 0;
 253                         while (*opts) {
 254                                 if (*opts == '"')
 255                                         break;
 256                                 if (*opts == '\\' && opts[1] == '"') {
 257                                         opts += 2;
 258                                         patterns[i++] = '"';
 259                                         continue;
 260                                 }
 261                                 patterns[i++] = *opts++;
 262                         }
 263                         if (!*opts) {
 264                                 debug("%.100s, line %lu: missing end quote",
 265                                     file, linenum);
 266                                 auth_debug_add("%.100s, line %lu: missing "
 267                                     "end quote", file, linenum);
 268                                 xfree(patterns);
 269                                 goto bad_option;
 270                         }
 271                         patterns[i] = '\0';
 272                         opts++;
 273                         p = patterns;
 274                         host = hpdelim(&p);
 275                         if (host == NULL || strlen(host) >= NI_MAXHOST) {
 276                                 debug("%.100s, line %lu: Bad permitopen "
 277                                     "specification <%.100s>", file, linenum,
 278                                     patterns);
 279                                 auth_debug_add("%.100s, line %lu: "
 280                                     "Bad permitopen specification", file,
 281                                     linenum);
 282                                 xfree(patterns);
 283                                 goto bad_option;
 284                         }
 285                         host = cleanhostname(host);
 286                         if (p == NULL || (port = a2port(p)) == 0) {
 287                                 debug("%.100s, line %lu: Bad permitopen port "
 288                                     "<%.100s>", file, linenum, p ? p : "");
 289                                 auth_debug_add("%.100s, line %lu: "
 290                                     "Bad permitopen port", file, linenum);
 291                                 xfree(patterns);
 292                                 goto bad_option;
 293                         }
 294                         if (options.allow_tcp_forwarding)
 295                                 channel_add_permitted_opens(host, port);
 296                         xfree(patterns);
 297                         goto next_option;
 298                 }
 299                 cp = "tunnel=\"";
 300                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 301                         char *tun = NULL;
 302                         opts += strlen(cp);
 303                         tun = xmalloc(strlen(opts) + 1);
 304                         i = 0;
 305                         while (*opts) {
 306                                 if (*opts == '"')
 307                                         break;
 308                                 tun[i++] = *opts++;
 309                         }
 310                         if (!*opts) {
 311                                 debug("%.100s, line %lu: missing end quote",
 312                                     file, linenum);
 313                                 auth_debug_add("%.100s, line %lu: missing end quote",
 314                                     file, linenum);
 315                                 xfree(tun);
 316                                 forced_tun_device = -1;
 317                                 goto bad_option;
 318                         }
 319                         tun[i] = '\0';
 320                         forced_tun_device = a2tun(tun, NULL);
 321                         xfree(tun);
 322                         if (forced_tun_device == SSH_TUNID_ERR) {
 323                                 debug("%.100s, line %lu: invalid tun device",
 324                                     file, linenum);
 325                                 auth_debug_add("%.100s, line %lu: invalid tun device",
 326                                     file, linenum);
 327                                 forced_tun_device = -1;
 328                                 goto bad_option;
 329                         }
 330                         auth_debug_add("Forced tun device: %d", forced_tun_device);
 331                         opts++;
 332                         goto next_option;
 333                 }
 334 next_option:
 335                 /*
 336                  * Skip the comma, and move to the next option
 337                  * (or break out if there are no more).
 338                  */
 339                 if (!*opts)
 340                         fatal("Bugs in auth-options.c option processing.");
 341                 if (*opts == ' ' || *opts == '\t')
 342                         break;          /* End of options. */
 343                 if (*opts != ',')
 344                         goto bad_option;
 345                 opts++;
 346                 /* Process the next option. */
 347         }
 348
 349         if (!use_privsep)
 350                 auth_debug_send();
 351
 352         /* grant access */
 353         return 1;
 354
 355 bad_option:
 356         logit("Bad options in %.100s file, line %lu: %.50s",
 357             file, linenum, opts);
 358         auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
 359             file, linenum, opts);
 360
 361         if (!use_privsep)
 362                 auth_debug_send();
 363
 364         /* deny access */
 365         return 0;
 366 }