openssh/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 1.20 2001/08/30 20:36:34 stevesk 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 #include "misc.h"
  24
  25 /* Flags set authorized_keys flags */
  26 int no_port_forwarding_flag = 0;
  27 int no_agent_forwarding_flag = 0;
  28 int no_x11_forwarding_flag = 0;
  29 int no_pty_flag = 0;
  30
  31 /* "command=" option. */
  32 char *forced_command = NULL;
  33
  34 /* "environment=" options. */
  35 struct envstring *custom_environment = NULL;
  36
  37 extern ServerOptions options;
  38
  39 void
  40 auth_clear_options(void)
  41 {
  42         no_agent_forwarding_flag = 0;
  43         no_port_forwarding_flag = 0;
  44         no_pty_flag = 0;
  45         no_x11_forwarding_flag = 0;
  46         while (custom_environment) {
  47                 struct envstring *ce = custom_environment;
  48                 custom_environment = ce->next;
  49                 xfree(ce->s);
  50                 xfree(ce);
  51         }
  52         if (forced_command) {
  53                 xfree(forced_command);
  54                 forced_command = NULL;
  55         }
  56         channel_clear_permitted_opens();
  57 }
  58
  59 /*
  60  * return 1 if access is granted, 0 if not.
  61  * side effect: sets key option flags
  62  */
  63 int
  64 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
  65 {
  66         const char *cp;
  67         int i;
  68
  69         /* reset options */
  70         auth_clear_options();
  71
  72         if (!opts)
  73                 return 1;
  74
  75         while (*opts && *opts != ' ' && *opts != '\t') {
  76                 cp = "no-port-forwarding";
  77                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  78                         packet_send_debug("Port forwarding disabled.");
  79                         no_port_forwarding_flag = 1;
  80                         opts += strlen(cp);
  81                         goto next_option;
  82                 }
  83                 cp = "no-agent-forwarding";
  84                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  85                         packet_send_debug("Agent forwarding disabled.");
  86                         no_agent_forwarding_flag = 1;
  87                         opts += strlen(cp);
  88                         goto next_option;
  89                 }
  90                 cp = "no-X11-forwarding";
  91                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  92                         packet_send_debug("X11 forwarding disabled.");
  93                         no_x11_forwarding_flag = 1;
  94                         opts += strlen(cp);
  95                         goto next_option;
  96                 }
  97                 cp = "no-pty";
  98                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  99                         packet_send_debug("Pty allocation disabled.");
 100                         no_pty_flag = 1;
 101                         opts += strlen(cp);
 102                         goto next_option;
 103                 }
 104                 cp = "command=\"";
 105                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 106                         opts += strlen(cp);
 107                         forced_command = xmalloc(strlen(opts) + 1);
 108                         i = 0;
 109                         while (*opts) {
 110                                 if (*opts == '"')
 111                                         break;
 112                                 if (*opts == '\\' && opts[1] == '"') {
 113                                         opts += 2;
 114                                         forced_command[i++] = '"';
 115                                         continue;
 116                                 }
 117                                 forced_command[i++] = *opts++;
 118                         }
 119                         if (!*opts) {
 120                                 debug("%.100s, line %lu: missing end quote",
 121                                     file, linenum);
 122                                 packet_send_debug("%.100s, line %lu: missing end quote",
 123                                     file, linenum);
 124                                 xfree(forced_command);
 125                                 forced_command = NULL;
 126                                 goto bad_option;
 127                         }
 128                         forced_command[i] = 0;
 129                         packet_send_debug("Forced command: %.900s", forced_command);
 130                         opts++;
 131                         goto next_option;
 132                 }
 133                 cp = "environment=\"";
 134                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 135                         char *s;
 136                         struct envstring *new_envstring;
 137
 138                         opts += strlen(cp);
 139                         s = xmalloc(strlen(opts) + 1);
 140                         i = 0;
 141                         while (*opts) {
 142                                 if (*opts == '"')
 143                                         break;
 144                                 if (*opts == '\\' && opts[1] == '"') {
 145                                         opts += 2;
 146                                         s[i++] = '"';
 147                                         continue;
 148                                 }
 149                                 s[i++] = *opts++;
 150                         }
 151                         if (!*opts) {
 152                                 debug("%.100s, line %lu: missing end quote",
 153                                     file, linenum);
 154                                 packet_send_debug("%.100s, line %lu: missing end quote",
 155                                     file, linenum);
 156                                 xfree(s);
 157                                 goto bad_option;
 158                         }
 159                         s[i] = 0;
 160                         packet_send_debug("Adding to environment: %.900s", s);
 161                         debug("Adding to environment: %.900s", s);
 162                         opts++;
 163                         new_envstring = xmalloc(sizeof(struct envstring));
 164                         new_envstring->s = s;
 165                         new_envstring->next = custom_environment;
 166                         custom_environment = new_envstring;
 167                         goto next_option;
 168                 }
 169                 cp = "from=\"";
 170                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 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                         if (match_host_and_ip(remote_host, remote_ip,
 199                             patterns) != 1) {
 200                                 xfree(patterns);
 201                                 log("Authentication tried for %.100s with "
 202                                     "correct key but not from a permitted "
 203                                     "host (host=%.200s, ip=%.200s).",
 204                                     pw->pw_name, remote_host, remote_ip);
 205                                 packet_send_debug("Your host '%.200s' is not "
 206                                     "permitted to use this key for login.",
 207                                     remote_host);
 208                                 /* deny access */
 209                                 return 0;
 210                         }
 211                         xfree(patterns);
 212                         /* Host name matches. */
 213                         goto next_option;
 214                 }
 215                 cp = "permitopen=\"";
 216                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 217                         char host[256], sport[6];
 218                         u_short port;
 219                         char *patterns = xmalloc(strlen(opts) + 1);
 220
 221                         opts += strlen(cp);
 222                         i = 0;
 223                         while (*opts) {
 224                                 if (*opts == '"')
 225                                         break;
 226                                 if (*opts == '\\' && opts[1] == '"') {
 227                                         opts += 2;
 228                                         patterns[i++] = '"';
 229                                         continue;
 230                                 }
 231                                 patterns[i++] = *opts++;
 232                         }
 233                         if (!*opts) {
 234                                 debug("%.100s, line %lu: missing end quote",
 235                                     file, linenum);
 236                                 packet_send_debug("%.100s, line %lu: missing end quote",
 237                                     file, linenum);
 238                                 xfree(patterns);
 239                                 goto bad_option;
 240                         }
 241                         patterns[i] = 0;
 242                         opts++;
 243                         if (sscanf(patterns, "%255[^:]:%5[0-9]", host, sport) != 2 &&
 244                             sscanf(patterns, "%255[^/]/%5[0-9]", host, sport) != 2) {
 245                                 debug("%.100s, line %lu: Bad permitopen specification "
 246                                     "<%.100s>", file, linenum, patterns);
 247                                 packet_send_debug("%.100s, line %lu: "
 248                                     "Bad permitopen specification", file, linenum);
 249                                 xfree(patterns);
 250                                 goto bad_option;
 251                         }
 252                         if ((port = a2port(sport)) == 0) {
 253                                 debug("%.100s, line %lu: Bad permitopen port <%.100s>",
 254                                     file, linenum, sport);
 255                                 packet_send_debug("%.100s, line %lu: "
 256                                     "Bad permitopen port", file, linenum);
 257                                 xfree(patterns);
 258                                 goto bad_option;
 259                         }
 260                         if (options.allow_tcp_forwarding)
 261                                 channel_add_permitted_opens(host, port);
 262                         xfree(patterns);
 263                         goto next_option;
 264                 }
 265 next_option:
 266                 /*
 267                  * Skip the comma, and move to the next option
 268                  * (or break out if there are no more).
 269                  */
 270                 if (!*opts)
 271                         fatal("Bugs in auth-options.c option processing.");
 272                 if (*opts == ' ' || *opts == '\t')
 273                         break;          /* End of options. */
 274                 if (*opts != ',')
 275                         goto bad_option;
 276                 opts++;
 277                 /* Process the next option. */
 278         }
 279         /* grant access */
 280         return 1;
 281
 282 bad_option:
 283         log("Bad options in %.100s file, line %lu: %.50s",
 284             file, linenum, opts);
 285         packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
 286             file, linenum, opts);
 287         /* deny access */
 288         return 0;
 289 }