auth-options.c

   1 /* $OpenBSD: auth-options.c,v 1.36 2006/07/06 16:03:53 stevesk 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 <pwd.h>
  18
  19 #include "xmalloc.h"
  20 #include "match.h"
  21 #include "log.h"
  22 #include "canohost.h"
  23 #include "channels.h"
  24 #include "auth-options.h"
  25 #include "servconf.h"
  26 #include "misc.h"
  27 #include "monitor_wrap.h"
  28 #include "auth.h"
  29
  30 /* Flags set authorized_keys flags */
  31 int no_port_forwarding_flag = 0;
  32 int no_agent_forwarding_flag = 0;
  33 int no_x11_forwarding_flag = 0;
  34 int no_pty_flag = 0;
  35
  36 /* "command=" option. */
  37 char *forced_command = NULL;
  38
  39 /* "environment=" options. */
  40 struct envstring *custom_environment = NULL;
  41
  42 /* "tunnel=" option. */
  43 int forced_tun_device = -1;
  44
  45 extern ServerOptions options;
  46
  47 void
  48 auth_clear_options(void)
  49 {
  50         no_agent_forwarding_flag = 0;
  51         no_port_forwarding_flag = 0;
  52         no_pty_flag = 0;
  53         no_x11_forwarding_flag = 0;
  54         while (custom_environment) {
  55                 struct envstring *ce = custom_environment;
  56                 custom_environment = ce->next;
  57                 xfree(ce->s);
  58                 xfree(ce);
  59         }
  60         if (forced_command) {
  61                 xfree(forced_command);
  62                 forced_command = NULL;
  63         }
  64         forced_tun_device = -1;
  65         channel_clear_permitted_opens();
  66         auth_debug_reset();
  67 }
  68
  69 /*
  70  * return 1 if access is granted, 0 if not.
  71  * side effect: sets key option flags
  72  */
  73 int
  74 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
  75 {
  76         const char *cp;
  77         int i;
  78
  79         /* reset options */
  80         auth_clear_options();
  81
  82         if (!opts)
  83                 return 1;
  84
  85         while (*opts && *opts != ' ' && *opts != '\t') {
  86                 cp = "no-port-forwarding";
  87                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  88                         auth_debug_add("Port forwarding disabled.");
  89                         no_port_forwarding_flag = 1;
  90                         opts += strlen(cp);
  91                         goto next_option;
  92                 }
  93                 cp = "no-agent-forwarding";
  94                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  95                         auth_debug_add("Agent forwarding disabled.");
  96                         no_agent_forwarding_flag = 1;
  97                         opts += strlen(cp);
  98                         goto next_option;
  99                 }
 100                 cp = "no-X11-forwarding";
 101                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 102                         auth_debug_add("X11 forwarding disabled.");
 103                         no_x11_forwarding_flag = 1;
 104                         opts += strlen(cp);
 105                         goto next_option;
 106                 }
 107                 cp = "no-pty";
 108                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 109                         auth_debug_add("Pty allocation disabled.");
 110                         no_pty_flag = 1;
 111                         opts += strlen(cp);
 112                         goto next_option;
 113                 }
 114                 cp = "command=\"";
 115                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 116                         opts += strlen(cp);
 117                         forced_command = xmalloc(strlen(opts) + 1);
 118                         i = 0;
 119                         while (*opts) {
 120                                 if (*opts == '"')
 121                                         break;
 122                                 if (*opts == '\\' && opts[1] == '"') {
 123                                         opts += 2;
 124                                         forced_command[i++] = '"';
 125                                         continue;
 126                                 }
 127                                 forced_command[i++] = *opts++;
 128                         }
 129                         if (!*opts) {
 130                                 debug("%.100s, line %lu: missing end quote",
 131                                     file, linenum);
 132                                 auth_debug_add("%.100s, line %lu: missing end quote",
 133                                     file, linenum);
 134                                 xfree(forced_command);
 135                                 forced_command = NULL;
 136                                 goto bad_option;
 137                         }
 138                         forced_command[i] = 0;
 139                         auth_debug_add("Forced command: %.900s", forced_command);
 140                         opts++;
 141                         goto next_option;
 142                 }
 143                 cp = "environment=\"";
 144                 if (options.permit_user_env &&
 145                     strncasecmp(opts, cp, strlen(cp)) == 0) {
 146                         char *s;
 147                         struct envstring *new_envstring;
 148
 149                         opts += strlen(cp);
 150                         s = xmalloc(strlen(opts) + 1);
 151                         i = 0;
 152                         while (*opts) {
 153                                 if (*opts == '"')
 154                                         break;
 155                                 if (*opts == '\\' && opts[1] == '"') {
 156                                         opts += 2;
 157                                         s[i++] = '"';
 158                                         continue;
 159                                 }
 160                                 s[i++] = *opts++;
 161                         }
 162                         if (!*opts) {
 163                                 debug("%.100s, line %lu: missing end quote",
 164                                     file, linenum);
 165                                 auth_debug_add("%.100s, line %lu: missing end quote",
 166                                     file, linenum);
 167                                 xfree(s);
 168                                 goto bad_option;
 169                         }
 170                         s[i] = 0;
 171                         auth_debug_add("Adding to environment: %.900s", s);
 172                         debug("Adding to environment: %.900s", s);
 173                         opts++;
 174                         new_envstring = xmalloc(sizeof(struct envstring));
 175                         new_envstring->s = s;
 176                         new_envstring->next = custom_environment;
 177                         custom_environment = new_envstring;
 178                         goto next_option;
 179                 }
 180                 cp = "from=\"";
 181                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 182                         const char *remote_ip = get_remote_ipaddr();
 183                         const char *remote_host = get_canonical_hostname(
 184                             options.use_dns);
 185                         char *patterns = xmalloc(strlen(opts) + 1);
 186
 187                         opts += strlen(cp);
 188                         i = 0;
 189                         while (*opts) {
 190                                 if (*opts == '"')
 191                                         break;
 192                                 if (*opts == '\\' && opts[1] == '"') {
 193                                         opts += 2;
 194                                         patterns[i++] = '"';
 195                                         continue;
 196                                 }
 197                                 patterns[i++] = *opts++;
 198                         }
 199                         if (!*opts) {
 200                                 debug("%.100s, line %lu: missing end quote",
 201                                     file, linenum);
 202                                 auth_debug_add("%.100s, line %lu: missing end quote",
 203                                     file, linenum);
 204                                 xfree(patterns);
 205                                 goto bad_option;
 206                         }
 207                         patterns[i] = 0;
 208                         opts++;
 209                         if (match_host_and_ip(remote_host, remote_ip,
 210                             patterns) != 1) {
 211                                 xfree(patterns);
 212                                 logit("Authentication tried for %.100s with "
 213                                     "correct key but not from a permitted "
 214                                     "host (host=%.200s, ip=%.200s).",
 215                                     pw->pw_name, remote_host, remote_ip);
 216                                 auth_debug_add("Your host '%.200s' is not "
 217                                     "permitted to use this key for login.",
 218                                     remote_host);
 219                                 /* deny access */
 220                                 return 0;
 221                         }
 222                         xfree(patterns);
 223                         /* Host name matches. */
 224                         goto next_option;
 225                 }
 226                 cp = "permitopen=\"";
 227                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 228                         char *host, *p;
 229                         u_short port;
 230                         char *patterns = xmalloc(strlen(opts) + 1);
 231
 232                         opts += strlen(cp);
 233                         i = 0;
 234                         while (*opts) {
 235                                 if (*opts == '"')
 236                                         break;
 237                                 if (*opts == '\\' && opts[1] == '"') {
 238                                         opts += 2;
 239                                         patterns[i++] = '"';
 240                                         continue;
 241                                 }
 242                                 patterns[i++] = *opts++;
 243                         }
 244                         if (!*opts) {
 245                                 debug("%.100s, line %lu: missing end quote",
 246                                     file, linenum);
 247                                 auth_debug_add("%.100s, line %lu: missing "
 248                                     "end quote", file, linenum);
 249                                 xfree(patterns);
 250                                 goto bad_option;
 251                         }
 252                         patterns[i] = 0;
 253                         opts++;
 254                         p = patterns;
 255                         host = hpdelim(&p);
 256                         if (host == NULL || strlen(host) >= NI_MAXHOST) {
 257                                 debug("%.100s, line %lu: Bad permitopen "
 258                                     "specification <%.100s>", file, linenum,
 259                                     patterns);
 260                                 auth_debug_add("%.100s, line %lu: "
 261                                     "Bad permitopen specification", file,
 262                                     linenum);
 263                                 xfree(patterns);
 264                                 goto bad_option;
 265                         }
 266                         host = cleanhostname(host);
 267                         if (p == NULL || (port = a2port(p)) == 0) {
 268                                 debug("%.100s, line %lu: Bad permitopen port "
 269                                     "<%.100s>", file, linenum, p ? p : "");
 270                                 auth_debug_add("%.100s, line %lu: "
 271                                     "Bad permitopen port", file, linenum);
 272                                 xfree(patterns);
 273                                 goto bad_option;
 274                         }
 275                         if (options.allow_tcp_forwarding)
 276                                 channel_add_permitted_opens(host, port);
 277                         xfree(patterns);
 278                         goto next_option;
 279                 }
 280                 cp = "tunnel=\"";
 281                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 282                         char *tun = NULL;
 283                         opts += strlen(cp);
 284                         tun = xmalloc(strlen(opts) + 1);
 285                         i = 0;
 286                         while (*opts) {
 287                                 if (*opts == '"')
 288                                         break;
 289                                 tun[i++] = *opts++;
 290                         }
 291                         if (!*opts) {
 292                                 debug("%.100s, line %lu: missing end quote",
 293                                     file, linenum);
 294                                 auth_debug_add("%.100s, line %lu: missing end quote",
 295                                     file, linenum);
 296                                 xfree(tun);
 297                                 forced_tun_device = -1;
 298                                 goto bad_option;
 299                         }
 300                         tun[i] = 0;
 301                         forced_tun_device = a2tun(tun, NULL);
 302                         xfree(tun);
 303                         if (forced_tun_device == SSH_TUNID_ERR) {
 304                                 debug("%.100s, line %lu: invalid tun device",
 305                                     file, linenum);
 306                                 auth_debug_add("%.100s, line %lu: invalid tun device",
 307                                     file, linenum);
 308                                 forced_tun_device = -1;
 309                                 goto bad_option;
 310                         }
 311                         auth_debug_add("Forced tun device: %d", forced_tun_device);
 312                         opts++;
 313                         goto next_option;
 314                 }
 315 next_option:
 316                 /*
 317                  * Skip the comma, and move to the next option
 318                  * (or break out if there are no more).
 319                  */
 320                 if (!*opts)
 321                         fatal("Bugs in auth-options.c option processing.");
 322                 if (*opts == ' ' || *opts == '\t')
 323                         break;          /* End of options. */
 324                 if (*opts != ',')
 325                         goto bad_option;
 326                 opts++;
 327                 /* Process the next option. */
 328         }
 329
 330         if (!use_privsep)
 331                 auth_debug_send();
 332
 333         /* grant access */
 334         return 1;
 335
 336 bad_option:
 337         logit("Bad options in %.100s file, line %lu: %.50s",
 338             file, linenum, opts);
 339         auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
 340             file, linenum, opts);
 341
 342         if (!use_privsep)
 343                 auth_debug_send();
 344
 345         /* deny access */
 346         return 0;
 347 }