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 1.14 2001/03/13 17:34:42 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
  65         /* reset options */
  66         auth_clear_options();
  67
  68         if (!opts)
  69                 return 1;
  70
  71         while (*opts && *opts != ' ' && *opts != '\t') {
  72                 cp = "no-port-forwarding";
  73                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  74                         packet_send_debug("Port forwarding disabled.");
  75                         no_port_forwarding_flag = 1;
  76                         opts += strlen(cp);
  77                         goto next_option;
  78                 }
  79                 cp = "no-agent-forwarding";
  80                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  81                         packet_send_debug("Agent forwarding disabled.");
  82                         no_agent_forwarding_flag = 1;
  83                         opts += strlen(cp);
  84                         goto next_option;
  85                 }
  86                 cp = "no-X11-forwarding";
  87                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  88                         packet_send_debug("X11 forwarding disabled.");
  89                         no_x11_forwarding_flag = 1;
  90                         opts += strlen(cp);
  91                         goto next_option;
  92                 }
  93                 cp = "no-pty";
  94                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
  95                         packet_send_debug("Pty allocation disabled.");
  96                         no_pty_flag = 1;
  97                         opts += strlen(cp);
  98                         goto next_option;
  99                 }
 100                 cp = "command=\"";
 101                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 102                         int i;
 103                         opts += strlen(cp);
 104                         forced_command = xmalloc(strlen(opts) + 1);
 105                         i = 0;
 106                         while (*opts) {
 107                                 if (*opts == '"')
 108                                         break;
 109                                 if (*opts == '\\' && opts[1] == '"') {
 110                                         opts += 2;
 111                                         forced_command[i++] = '"';
 112                                         continue;
 113                                 }
 114                                 forced_command[i++] = *opts++;
 115                         }
 116                         if (!*opts) {
 117                                 debug("%.100s, line %lu: missing end quote",
 118                                     file, linenum);
 119                                 packet_send_debug("%.100s, line %lu: missing end quote",
 120                                     file, linenum);
 121                                 xfree(forced_command);
 122                                 forced_command = NULL;
 123                                 goto bad_option;
 124                         }
 125                         forced_command[i] = 0;
 126                         packet_send_debug("Forced command: %.900s", forced_command);
 127                         opts++;
 128                         goto next_option;
 129                 }
 130                 cp = "environment=\"";
 131                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 132                         int i;
 133                         char *s;
 134                         struct envstring *new_envstring;
 135                         opts += strlen(cp);
 136                         s = xmalloc(strlen(opts) + 1);
 137                         i = 0;
 138                         while (*opts) {
 139                                 if (*opts == '"')
 140                                         break;
 141                                 if (*opts == '\\' && opts[1] == '"') {
 142                                         opts += 2;
 143                                         s[i++] = '"';
 144                                         continue;
 145                                 }
 146                                 s[i++] = *opts++;
 147                         }
 148                         if (!*opts) {
 149                                 debug("%.100s, line %lu: missing end quote",
 150                                     file, linenum);
 151                                 packet_send_debug("%.100s, line %lu: missing end quote",
 152                                     file, linenum);
 153                                 xfree(s);
 154                                 goto bad_option;
 155                         }
 156                         s[i] = 0;
 157                         packet_send_debug("Adding to environment: %.900s", s);
 158                         debug("Adding to environment: %.900s", s);
 159                         opts++;
 160                         new_envstring = xmalloc(sizeof(struct envstring));
 161                         new_envstring->s = s;
 162                         new_envstring->next = custom_environment;
 163                         custom_environment = new_envstring;
 164                         goto next_option;
 165                 }
 166                 cp = "from=\"";
 167                 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
 168                         int mname, mip;
 169                         const char *remote_ip = get_remote_ipaddr();
 170                         const char *remote_host = get_canonical_hostname(
 171                             options.reverse_mapping_check);
 172                         char *patterns = xmalloc(strlen(opts) + 1);
 173                         int i;
 174                         opts += strlen(cp);
 175                         i = 0;
 176                         while (*opts) {
 177                                 if (*opts == '"')
 178                                         break;
 179                                 if (*opts == '\\' && opts[1] == '"') {
 180                                         opts += 2;
 181                                         patterns[i++] = '"';
 182                                         continue;
 183                                 }
 184                                 patterns[i++] = *opts++;
 185                         }
 186                         if (!*opts) {
 187                                 debug("%.100s, line %lu: missing end quote",
 188                                     file, linenum);
 189                                 packet_send_debug("%.100s, line %lu: missing end quote",
 190                                     file, linenum);
 191                                 xfree(patterns);
 192                                 goto bad_option;
 193                         }
 194                         patterns[i] = 0;
 195                         opts++;
 196                         /*
 197                          * Deny access if we get a negative
 198                          * match for the hostname or the ip
 199                          * or if we get not match at all
 200                          */
 201                         mname = match_hostname(remote_host, patterns,
 202                             strlen(patterns));
 203                         mip = match_hostname(remote_ip, patterns,
 204                             strlen(patterns));
 205                         xfree(patterns);
 206                         if (mname == -1 || mip == -1 ||
 207                             (mname != 1 && mip != 1)) {
 208                                 log("Authentication tried for %.100s with "
 209                                     "correct key but not from a permitted "
 210                                     "host (host=%.200s, ip=%.200s).",
 211                                     pw->pw_name, remote_host, remote_ip);
 212                                 packet_send_debug("Your host '%.200s' is not "
 213                                     "permitted to use this key for login.",
 214                                     remote_host);
 215                                 /* deny access */
 216                                 return 0;
 217                         }
 218                         /* Host name matches. */
 219                         goto next_option;
 220                 }
 221 next_option:
 222                 /*
 223                  * Skip the comma, and move to the next option
 224                  * (or break out if there are no more).
 225                  */
 226                 if (!*opts)
 227                         fatal("Bugs in auth-options.c option processing.");
 228                 if (*opts == ' ' || *opts == '\t')
 229                         break;          /* End of options. */
 230                 if (*opts != ',')
 231                         goto bad_option;
 232                 opts++;
 233                 /* Process the next option. */
 234         }
 235         /* grant access */
 236         return 1;
 237
 238 bad_option:
 239         log("Bad options in %.100s file, line %lu: %.50s",
 240             file, linenum, opts);
 241         packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
 242             file, linenum, opts);
 243         /* deny access */
 244         return 0;
 245 }