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 1.16 2001/03/18 12:07:52 markus Exp $");
  14
  15 #include "packet.h"
  16 #include "xmalloc.h"
  17 #include "match.h"
  18 #include "log.h"
  19 #include "canohost.h"
  20 #include "channels.h"
  21 #include "auth-options.h"
  22 #include "servconf.h"
  23
  24 /* Flags set authorized_keys flags */
  25 int no_port_forwarding_flag = 0;
  26 int no_agent_forwarding_flag = 0;
  27 int no_x11_forwarding_flag = 0;
  28 int no_pty_flag = 0;
  29
  30 /* "command=" option. */
  31 char *forced_command = NULL;
  32
  33 /* "environment=" options. */
  34 struct envstring *custom_environment = NULL;
  35
  36 extern ServerOptions options;
  37
  38 void
  39 auth_clear_options(void)
  40 {
  41         no_agent_forwarding_flag = 0;
  42         no_port_forwarding_flag = 0;
  43         no_pty_flag = 0;
  44         no_x11_forwarding_flag = 0;
  45         while (custom_environment) {
  46                 struct envstring *ce = custom_environment;
  47                 custom_environment = ce->next;
  48                 xfree(ce->s);
  49                 xfree(ce);
  50         }
  51         if (forced_command) {
  52                 xfree(forced_command);
  53                 forced_command = NULL;
  54         }
  55         channel_clear_permitted_opens();
  56 }
  57
  58 /*
  59  * return 1 if access is granted, 0 if not.
  60  * side effect: sets key option flags
  61  */
  62 int
  63 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
  64 {
  65         const char *cp;
  66         int i;
  67
  68         /* reset options */
  69         auth_clear_options();
  70
  71         if (!opts)
  72                 return 1;
  73
  74         while (*opts && *opts != ' ' && *opts != '\t') {
  75                 cp = "no-port-forwarding";
  76                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  77                         packet_send_debug("Port forwarding disabled.");
  78                         no_port_forwarding_flag = 1;
  79                         opts += strlen(cp);
  80                         goto next_option;
  81                 }
  82                 cp = "no-agent-forwarding";
  83                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  84                         packet_send_debug("Agent forwarding disabled.");
  85                         no_agent_forwarding_flag = 1;
  86                         opts += strlen(cp);
  87                         goto next_option;
  88                 }
  89                 cp = "no-X11-forwarding";
  90                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  91                         packet_send_debug("X11 forwarding disabled.");
  92                         no_x11_forwarding_flag = 1;
  93                         opts += strlen(cp);
  94                         goto next_option;
  95                 }
  96                 cp = "no-pty";
  97                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  98                         packet_send_debug("Pty allocation disabled.");
  99                         no_pty_flag = 1;
 100                         opts += strlen(cp);
 101                         goto next_option;
 102                 }
 103                 cp = "command=\"";
 104                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 105                         opts += strlen(cp);
 106                         forced_command = xmalloc(strlen(opts) + 1);
 107                         i = 0;
 108                         while (*opts) {
 109                                 if (*opts == '"')
 110                                         break;
 111                                 if (*opts == '\\' && opts[1] == '"') {
 112                                         opts += 2;
 113                                         forced_command[i++] = '"';
 114                                         continue;
 115                                 }
 116                                 forced_command[i++] = *opts++;
 117                         }
 118                         if (!*opts) {
 119                                 debug("%.100s, line %lu: missing end quote",
 120                                     file, linenum);
 121                                 packet_send_debug("%.100s, line %lu: missing end quote",
 122                                     file, linenum);
 123                                 xfree(forced_command);
 124                                 forced_command = NULL;
 125                                 goto bad_option;
 126                         }
 127                         forced_command[i] = 0;
 128                         packet_send_debug("Forced command: %.900s", forced_command);
 129                         opts++;
 130                         goto next_option;
 131                 }
 132                 cp = "environment=\"";
 133                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 134                         char *s;
 135                         struct envstring *new_envstring;
 136
 137                         opts += strlen(cp);
 138                         s = xmalloc(strlen(opts) + 1);
 139                         i = 0;
 140                         while (*opts) {
 141                                 if (*opts == '"')
 142                                         break;
 143                                 if (*opts == '\\' && opts[1] == '"') {
 144                                         opts += 2;
 145                                         s[i++] = '"';
 146                                         continue;
 147                                 }
 148                                 s[i++] = *opts++;
 149                         }
 150                         if (!*opts) {
 151                                 debug("%.100s, line %lu: missing end quote",
 152                                     file, linenum);
 153                                 packet_send_debug("%.100s, line %lu: missing end quote",
 154                                     file, linenum);
 155                                 xfree(s);
 156                                 goto bad_option;
 157                         }
 158                         s[i] = 0;
 159                         packet_send_debug("Adding to environment: %.900s", s);
 160                         debug("Adding to environment: %.900s", s);
 161                         opts++;
 162                         new_envstring = xmalloc(sizeof(struct envstring));
 163                         new_envstring->s = s;
 164                         new_envstring->next = custom_environment;
 165                         custom_environment = new_envstring;
 166                         goto next_option;
 167                 }
 168                 cp = "from=\"";
 169                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 170                         int mname, mip;
 171                         const char *remote_ip = get_remote_ipaddr();
 172                         const char *remote_host = get_canonical_hostname(
 173                             options.reverse_mapping_check);
 174                         char *patterns = xmalloc(strlen(opts) + 1);
 175
 176                         opts += strlen(cp);
 177                         i = 0;
 178                         while (*opts) {
 179                                 if (*opts == '"')
 180                                         break;
 181                                 if (*opts == '\\' && opts[1] == '"') {
 182                                         opts += 2;
 183                                         patterns[i++] = '"';
 184                                         continue;
 185                                 }
 186                                 patterns[i++] = *opts++;
 187                         }
 188                         if (!*opts) {
 189                                 debug("%.100s, line %lu: missing end quote",
 190                                     file, linenum);
 191                                 packet_send_debug("%.100s, line %lu: missing end quote",
 192                                     file, linenum);
 193                                 xfree(patterns);
 194                                 goto bad_option;
 195                         }
 196                         patterns[i] = 0;
 197                         opts++;
 198                         /*
 199                          * Deny access if we get a negative
 200                          * match for the hostname or the ip
 201                          * or if we get not match at all
 202                          */
 203                         mname = match_hostname(remote_host, patterns,
 204                             strlen(patterns));
 205                         mip = match_hostname(remote_ip, patterns,
 206                             strlen(patterns));
 207                         xfree(patterns);
 208                         if (mname == -1 || mip == -1 ||
 209                             (mname != 1 && mip != 1)) {
 210                                 log("Authentication tried for %.100s with "
 211                                     "correct key but not from a permitted "
 212                                     "host (host=%.200s, ip=%.200s).",
 213                                     pw->pw_name, remote_host, remote_ip);
 214                                 packet_send_debug("Your host '%.200s' is not "
 215                                     "permitted to use this key for login.",
 216                                     remote_host);
 217                                 /* deny access */
 218                                 return 0;
 219                         }
 220                         /* Host name matches. */
 221                         goto next_option;
 222                 }
 223                 cp = "permitopen=\"";
 224                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 225                         u_short port;
 226                         char *c, *ep;
 227                         char *patterns = xmalloc(strlen(opts) + 1);
 228
 229                         opts += strlen(cp);
 230                         i = 0;
 231                         while (*opts) {
 232                                 if (*opts == '"')
 233                                         break;
 234                                 if (*opts == '\\' && opts[1] == '"') {
 235                                         opts += 2;
 236                                         patterns[i++] = '"';
 237                                         continue;
 238                                 }
 239                                 patterns[i++] = *opts++;
 240                         }
 241                         if (!*opts) {
 242                                 debug("%.100s, line %lu: missing end quote",
 243                                     file, linenum);
 244                                 packet_send_debug("%.100s, line %lu: missing end quote",
 245                                     file, linenum);
 246                                 xfree(patterns);
 247                                 goto bad_option;
 248                         }
 249                         patterns[i] = 0;
 250                         opts++;
 251                         c = strchr(patterns, ':');
 252                         if (c == NULL) {
 253                                 debug("%.100s, line %lu: permitopen: missing colon <%.100s>",
 254                                     file, linenum, patterns);
 255                                 packet_send_debug("%.100s, line %lu: missing colon",
 256                                     file, linenum);
 257                                 xfree(patterns);
 258                                 goto bad_option;
 259                         }
 260                         *c = 0;
 261                         c++;
 262                         port = strtol(c, &ep, 0);
 263                         if (c == ep) {
 264                                 debug("%.100s, line %lu: permitopen: missing port <%.100s>",
 265                                     file, linenum, patterns);
 266                                 packet_send_debug("%.100s, line %lu: missing port",
 267                                     file, linenum);
 268                                 xfree(patterns);
 269                                 goto bad_option;
 270                         }
 271                         if (options.allow_tcp_forwarding)
 272                                 channel_add_permitted_opens(patterns, port);
 273                         xfree(patterns);
 274                         goto next_option;
 275                 }
 276 next_option:
 277                 /*
 278                  * Skip the comma, and move to the next option
 279                  * (or break out if there are no more).
 280                  */
 281                 if (!*opts)
 282                         fatal("Bugs in auth-options.c option processing.");
 283                 if (*opts == ' ' || *opts == '\t')
 284                         break;          /* End of options. */
 285                 if (*opts != ',')
 286                         goto bad_option;
 287                 opts++;
 288                 /* Process the next option. */
 289         }
 290         /* grant access */
 291         return 1;
 292
 293 bad_option:
 294         log("Bad options in %.100s file, line %lu: %.50s",
 295             file, linenum, opts);
 296         packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
 297             file, linenum, opts);
 298         /* deny access */
 299         return 0;
 300 }