auth-options.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * As far as I am concerned, the code I have written for this software
   6  * can be used freely for any purpose.  Any derived versions of this
   7  * software must be clearly marked as such, and if the derived work is
   8  * incompatible with the protocol description in the RFC file, it must be
   9  * called by a name other than "ssh" or "Secure Shell".
  10  */
  11
  12 #include "includes.h"
  13 RCSID("$OpenBSD: auth-options.c,v 1.31 2005/03/10 22:40:38 deraadt Exp $");
  14
  15 #include "xmalloc.h"
  16 #include "match.h"
  17 #include "log.h"
  18 #include "canohost.h"
  19 #include "channels.h"
  20 #include "auth-options.h"
  21 #include "servconf.h"
  22 #include "misc.h"
  23 #include "monitor_wrap.h"
  24 #include "auth.h"
  25
  26 /* Flags set authorized_keys flags */
  27 int no_port_forwarding_flag = 0;
  28 int no_agent_forwarding_flag = 0;
  29 int no_x11_forwarding_flag = 0;
  30 int no_pty_flag = 0;
  31
  32 /* "command=" option. */
  33 char *forced_command = NULL;
  34
  35 /* "environment=" options. */
  36 struct envstring *custom_environment = NULL;
  37
  38 extern ServerOptions options;
  39
  40 void
  41 auth_clear_options(void)
  42 {
  43         no_agent_forwarding_flag = 0;
  44         no_port_forwarding_flag = 0;
  45         no_pty_flag = 0;
  46         no_x11_forwarding_flag = 0;
  47         while (custom_environment) {
  48                 struct envstring *ce = custom_environment;
  49                 custom_environment = ce->next;
  50                 xfree(ce->s);
  51                 xfree(ce);
  52         }
  53         if (forced_command) {
  54                 xfree(forced_command);
  55                 forced_command = NULL;
  56         }
  57         channel_clear_permitted_opens();
  58         auth_debug_reset();
  59 }
  60
  61 /*
  62  * return 1 if access is granted, 0 if not.
  63  * side effect: sets key option flags
  64  */
  65 int
  66 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
  67 {
  68         const char *cp;
  69         int i;
  70
  71         /* reset options */
  72         auth_clear_options();
  73
  74         if (!opts)
  75                 return 1;
  76
  77         while (*opts && *opts != ' ' && *opts != '\t') {
  78                 cp = "no-port-forwarding";
  79                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  80                         auth_debug_add("Port forwarding disabled.");
  81                         no_port_forwarding_flag = 1;
  82                         opts += strlen(cp);
  83                         goto next_option;
  84                 }
  85                 cp = "no-agent-forwarding";
  86                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  87                         auth_debug_add("Agent forwarding disabled.");
  88                         no_agent_forwarding_flag = 1;
  89                         opts += strlen(cp);
  90                         goto next_option;
  91                 }
  92                 cp = "no-X11-forwarding";
  93                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  94                         auth_debug_add("X11 forwarding disabled.");
  95                         no_x11_forwarding_flag = 1;
  96                         opts += strlen(cp);
  97                         goto next_option;
  98                 }
  99                 cp = "no-pty";
 100                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 101                         auth_debug_add("Pty allocation disabled.");
 102                         no_pty_flag = 1;
 103                         opts += strlen(cp);
 104                         goto next_option;
 105                 }
 106                 cp = "command=\"";
 107                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 108                         opts += strlen(cp);
 109                         forced_command = xmalloc(strlen(opts) + 1);
 110                         i = 0;
 111                         while (*opts) {
 112                                 if (*opts == '"')
 113                                         break;
 114                                 if (*opts == '\\' && opts[1] == '"') {
 115                                         opts += 2;
 116                                         forced_command[i++] = '"';
 117                                         continue;
 118                                 }
 119                                 forced_command[i++] = *opts++;
 120                         }
 121                         if (!*opts) {
 122                                 debug("%.100s, line %lu: missing end quote",
 123                                     file, linenum);
 124                                 auth_debug_add("%.100s, line %lu: missing end quote",
 125                                     file, linenum);
 126                                 xfree(forced_command);
 127                                 forced_command = NULL;
 128                                 goto bad_option;
 129                         }
 130                         forced_command[i] = 0;
 131                         auth_debug_add("Forced command: %.900s", forced_command);
 132                         opts++;
 133                         goto next_option;
 134                 }
 135                 cp = "environment=\"";
 136                 if (options.permit_user_env &&
 137                     strncasecmp(opts, cp, strlen(cp)) == 0) {
 138                         char *s;
 139                         struct envstring *new_envstring;
 140
 141                         opts += strlen(cp);
 142                         s = xmalloc(strlen(opts) + 1);
 143                         i = 0;
 144                         while (*opts) {
 145                                 if (*opts == '"')
 146                                         break;
 147                                 if (*opts == '\\' && opts[1] == '"') {
 148                                         opts += 2;
 149                                         s[i++] = '"';
 150                                         continue;
 151                                 }
 152                                 s[i++] = *opts++;
 153                         }
 154                         if (!*opts) {
 155                                 debug("%.100s, line %lu: missing end quote",
 156                                     file, linenum);
 157                                 auth_debug_add("%.100s, line %lu: missing end quote",
 158                                     file, linenum);
 159                                 xfree(s);
 160                                 goto bad_option;
 161                         }
 162                         s[i] = 0;
 163                         auth_debug_add("Adding to environment: %.900s", s);
 164                         debug("Adding to environment: %.900s", s);
 165                         opts++;
 166                         new_envstring = xmalloc(sizeof(struct envstring));
 167                         new_envstring->s = s;
 168                         new_envstring->next = custom_environment;
 169                         custom_environment = new_envstring;
 170                         goto next_option;
 171                 }
 172                 cp = "from=\"";
 173                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 174                         const char *remote_ip = get_remote_ipaddr();
 175                         const char *remote_host = get_canonical_hostname(
 176                             options.use_dns);
 177                         char *patterns = xmalloc(strlen(opts) + 1);
 178
 179                         opts += strlen(cp);
 180                         i = 0;
 181                         while (*opts) {
 182                                 if (*opts == '"')
 183                                         break;
 184                                 if (*opts == '\\' && opts[1] == '"') {
 185                                         opts += 2;
 186                                         patterns[i++] = '"';
 187                                         continue;
 188                                 }
 189                                 patterns[i++] = *opts++;
 190                         }
 191                         if (!*opts) {
 192                                 debug("%.100s, line %lu: missing end quote",
 193                                     file, linenum);
 194                                 auth_debug_add("%.100s, line %lu: missing end quote",
 195                                     file, linenum);
 196                                 xfree(patterns);
 197                                 goto bad_option;
 198                         }
 199                         patterns[i] = 0;
 200                         opts++;
 201                         if (match_host_and_ip(remote_host, remote_ip,
 202                             patterns) != 1) {
 203                                 xfree(patterns);
 204                                 logit("Authentication tried for %.100s with "
 205                                     "correct key but not from a permitted "
 206                                     "host (host=%.200s, ip=%.200s).",
 207                                     pw->pw_name, remote_host, remote_ip);
 208                                 auth_debug_add("Your host '%.200s' is not "
 209                                     "permitted to use this key for login.",
 210                                     remote_host);
 211                                 /* deny access */
 212                                 return 0;
 213                         }
 214                         xfree(patterns);
 215                         /* Host name matches. */
 216                         goto next_option;
 217                 }
 218                 cp = "permitopen=\"";
 219                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 220                         char *host, *p;
 221                         u_short port;
 222                         char *patterns = xmalloc(strlen(opts) + 1);
 223
 224                         opts += strlen(cp);
 225                         i = 0;
 226                         while (*opts) {
 227                                 if (*opts == '"')
 228                                         break;
 229                                 if (*opts == '\\' && opts[1] == '"') {
 230                                         opts += 2;
 231                                         patterns[i++] = '"';
 232                                         continue;
 233                                 }
 234                                 patterns[i++] = *opts++;
 235                         }
 236                         if (!*opts) {
 237                                 debug("%.100s, line %lu: missing end quote",
 238                                     file, linenum);
 239                                 auth_debug_add("%.100s, line %lu: missing "
 240                                     "end quote", file, linenum);
 241                                 xfree(patterns);
 242                                 goto bad_option;
 243                         }
 244                         patterns[i] = 0;
 245                         opts++;
 246                         p = patterns;
 247                         host = hpdelim(&p);
 248                         if (host == NULL || strlen(host) >= NI_MAXHOST) {
 249                                 debug("%.100s, line %lu: Bad permitopen "
 250                                     "specification <%.100s>", file, linenum,
 251                                     patterns);
 252                                 auth_debug_add("%.100s, line %lu: "
 253                                     "Bad permitopen specification", file,
 254                                     linenum);
 255                                 xfree(patterns);
 256                                 goto bad_option;
 257                         }
 258                         host = cleanhostname(host);
 259                         if (p == NULL || (port = a2port(p)) == 0) {
 260                                 debug("%.100s, line %lu: Bad permitopen port "
 261                                     "<%.100s>", file, linenum, p ? p : "");
 262                                 auth_debug_add("%.100s, line %lu: "
 263                                     "Bad permitopen port", file, linenum);
 264                                 xfree(patterns);
 265                                 goto bad_option;
 266                         }
 267                         if (options.allow_tcp_forwarding)
 268                                 channel_add_permitted_opens(host, port);
 269                         xfree(patterns);
 270                         goto next_option;
 271                 }
 272 next_option:
 273                 /*
 274                  * Skip the comma, and move to the next option
 275                  * (or break out if there are no more).
 276                  */
 277                 if (!*opts)
 278                         fatal("Bugs in auth-options.c option processing.");
 279                 if (*opts == ' ' || *opts == '\t')
 280                         break;          /* End of options. */
 281                 if (*opts != ',')
 282                         goto bad_option;
 283                 opts++;
 284                 /* Process the next option. */
 285         }
 286
 287         if (!use_privsep)
 288                 auth_debug_send();
 289
 290         /* grant access */
 291         return 1;
 292
 293 bad_option:
 294         logit("Bad options in %.100s file, line %lu: %.50s",
 295             file, linenum, opts);
 296         auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
 297             file, linenum, opts);
 298
 299         if (!use_privsep)
 300                 auth_debug_send();
 301
 302         /* deny access */
 303         return 0;
 304 }