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 1.12 2001/02/03 10:08:36 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 "auth-options.h"
  21 #include "servconf.h"
  22
  23 /* Flags set authorized_keys flags */
  24 int no_port_forwarding_flag = 0;
  25 int no_agent_forwarding_flag = 0;
  26 int no_x11_forwarding_flag = 0;
  27 int no_pty_flag = 0;
  28
  29 /* "command=" option. */
  30 char *forced_command = NULL;
  31
  32 /* "environment=" options. */
  33 struct envstring *custom_environment = NULL;
  34
  35 extern ServerOptions options;
  36
  37 void
  38 auth_clear_options(void)
  39 {
  40         no_agent_forwarding_flag = 0;
  41         no_port_forwarding_flag = 0;
  42         no_pty_flag = 0;
  43         no_x11_forwarding_flag = 0;
  44         while (custom_environment) {
  45                 struct envstring *ce = custom_environment;
  46                 custom_environment = ce->next;
  47                 xfree(ce->s);
  48                 xfree(ce);
  49         }
  50         if (forced_command) {
  51                 xfree(forced_command);
  52                 forced_command = NULL;
  53         }
  54 }
  55
  56 /*
  57  * return 1 if access is granted, 0 if not.
  58  * side effect: sets key option flags
  59  */
  60 int
  61 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
  62 {
  63         const char *cp;
  64         if (!opts)
  65                 return 1;
  66
  67         /* reset options */
  68         auth_clear_options();
  69
  70         while (*opts && *opts != ' ' && *opts != '\t') {
  71                 cp = "no-port-forwarding";
  72                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  73                         packet_send_debug("Port forwarding disabled.");
  74                         no_port_forwarding_flag = 1;
  75                         opts += strlen(cp);
  76                         goto next_option;
  77                 }
  78                 cp = "no-agent-forwarding";
  79                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  80                         packet_send_debug("Agent forwarding disabled.");
  81                         no_agent_forwarding_flag = 1;
  82                         opts += strlen(cp);
  83                         goto next_option;
  84                 }
  85                 cp = "no-X11-forwarding";
  86                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  87                         packet_send_debug("X11 forwarding disabled.");
  88                         no_x11_forwarding_flag = 1;
  89                         opts += strlen(cp);
  90                         goto next_option;
  91                 }
  92                 cp = "no-pty";
  93                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  94                         packet_send_debug("Pty allocation disabled.");
  95                         no_pty_flag = 1;
  96                         opts += strlen(cp);
  97                         goto next_option;
  98                 }
  99                 cp = "command=\"";
 100                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 101                         int i;
 102                         opts += strlen(cp);
 103                         forced_command = xmalloc(strlen(opts) + 1);
 104                         i = 0;
 105                         while (*opts) {
 106                                 if (*opts == '"')
 107                                         break;
 108                                 if (*opts == '\\' && opts[1] == '"') {
 109                                         opts += 2;
 110                                         forced_command[i++] = '"';
 111                                         continue;
 112                                 }
 113                                 forced_command[i++] = *opts++;
 114                         }
 115                         if (!*opts) {
 116                                 debug("%.100s, line %lu: missing end quote",
 117                                     file, linenum);
 118                                 packet_send_debug("%.100s, line %lu: missing end quote",
 119                                     file, linenum);
 120                                 continue;
 121                         }
 122                         forced_command[i] = 0;
 123                         packet_send_debug("Forced command: %.900s", forced_command);
 124                         opts++;
 125                         goto next_option;
 126                 }
 127                 cp = "environment=\"";
 128                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 129                         int i;
 130                         char *s;
 131                         struct envstring *new_envstring;
 132                         opts += strlen(cp);
 133                         s = xmalloc(strlen(opts) + 1);
 134                         i = 0;
 135                         while (*opts) {
 136                                 if (*opts == '"')
 137                                         break;
 138                                 if (*opts == '\\' && opts[1] == '"') {
 139                                         opts += 2;
 140                                         s[i++] = '"';
 141                                         continue;
 142                                 }
 143                                 s[i++] = *opts++;
 144                         }
 145                         if (!*opts) {
 146                                 debug("%.100s, line %lu: missing end quote",
 147                                     file, linenum);
 148                                 packet_send_debug("%.100s, line %lu: missing end quote",
 149                                     file, linenum);
 150                                 continue;
 151                         }
 152                         s[i] = 0;
 153                         packet_send_debug("Adding to environment: %.900s", s);
 154                         debug("Adding to environment: %.900s", s);
 155                         opts++;
 156                         new_envstring = xmalloc(sizeof(struct envstring));
 157                         new_envstring->s = s;
 158                         new_envstring->next = custom_environment;
 159                         custom_environment = new_envstring;
 160                         goto next_option;
 161                 }
 162                 cp = "from=\"";
 163                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 164                         int mname, mip;
 165                         const char *remote_ip = get_remote_ipaddr();
 166                         const char *remote_host = get_canonical_hostname(
 167                             options.reverse_mapping_check);
 168                         char *patterns = xmalloc(strlen(opts) + 1);
 169                         int i;
 170                         opts += strlen(cp);
 171                         i = 0;
 172                         while (*opts) {
 173                                 if (*opts == '"')
 174                                         break;
 175                                 if (*opts == '\\' && opts[1] == '"') {
 176                                         opts += 2;
 177                                         patterns[i++] = '"';
 178                                         continue;
 179                                 }
 180                                 patterns[i++] = *opts++;
 181                         }
 182                         if (!*opts) {
 183                                 debug("%.100s, line %lu: missing end quote",
 184                                     file, linenum);
 185                                 packet_send_debug("%.100s, line %lu: missing end quote",
 186                                     file, linenum);
 187                                 continue;
 188                         }
 189                         patterns[i] = 0;
 190                         opts++;
 191                         /*
 192                          * Deny access if we get a negative
 193                          * match for the hostname or the ip
 194                          * or if we get not match at all
 195                          */
 196                         mname = match_hostname(remote_host, patterns,
 197                             strlen(patterns));
 198                         mip = match_hostname(remote_ip, patterns,
 199                             strlen(patterns));
 200                         xfree(patterns);
 201                         if (mname == -1 || mip == -1 ||
 202                             (mname != 1 && mip != 1)) {
 203                                 log("Authentication tried for %.100s with "
 204                                     "correct key but not from a permitted "
 205                                     "host (host=%.200s, ip=%.200s).",
 206                                     pw->pw_name, remote_host, remote_ip);
 207                                 packet_send_debug("Your host '%.200s' is not "
 208                                     "permitted to use this key for login.",
 209                                     remote_host);
 210                                 /* deny access */
 211                                 return 0;
 212                         }
 213                         /* Host name matches. */
 214                         goto next_option;
 215                 }
 216 next_option:
 217                 /*
 218                  * Skip the comma, and move to the next option
 219                  * (or break out if there are no more).
 220                  */
 221                 if (!*opts)
 222                         fatal("Bugs in auth-options.c option processing.");
 223                 if (*opts == ' ' || *opts == '\t')
 224                         break;          /* End of options. */
 225                 if (*opts != ',')
 226                         goto bad_option;
 227                 opts++;
 228                 /* Process the next option. */
 229         }
 230         /* grant access */
 231         return 1;
 232
 233 bad_option:
 234         log("Bad options in %.100s file, line %lu: %.50s",
 235             file, linenum, opts);
 236         packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
 237             file, linenum, opts);
 238         /* deny access */
 239         return 0;
 240 }