epan/dissectors/packet-kpasswd.c

   1 /* packet-kpasswd.c
   2  * Routines for kpasswd packet dissection
   3  *    Ronnie Sahlberg 2003
   4  *
   5  * See RFC 3244
   6  *
   7  * $Id$
   8  *
   9  * Wireshark - Network traffic analyzer
  10  * By Gerald Combs <gerald@wireshark.org>
  11  * Copyright 1998 Gerald Combs
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * as published by the Free Software Foundation; either version 2
  16  * of the License, or (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  26  */
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <epan/packet.h>
  33 #include <epan/asn1.h>
  34 #include "packet-tcp.h"
  35 #include "packet-kerberos.h"
  36 #include "packet-ber.h"
  37 #include <epan/prefs.h>
  38
  39 /* Desegment Kerberos over TCP messages */
  40 static gboolean kpasswd_desegment = TRUE;
  41
  42 static int proto_kpasswd = -1;
  43 static int hf_kpasswd_message_len = -1;
  44 static int hf_kpasswd_version = -1;
  45 static int hf_kpasswd_result = -1;
  46 static int hf_kpasswd_result_string = -1;
  47 static int hf_kpasswd_newpassword = -1;
  48 static int hf_kpasswd_ap_req_len = -1;
  49 static int hf_kpasswd_ap_req_data = -1;
  50 static int hf_kpasswd_krb_priv_message = -1;
  51 static int hf_kpasswd_ChangePasswdData = -1;
  52
  53 static gint ett_kpasswd = -1;
  54 static gint ett_ap_req_data = -1;
  55 static gint ett_krb_priv_message = -1;
  56 static gint ett_ChangePasswdData = -1;
  57
  58
  59 #define UDP_PORT_KPASSWD                464
  60 #define TCP_PORT_KPASSWD                464
  61
  62
  63 static const value_string vers_vals[] = {
  64         { 0x0001,       "Reply" },
  65         { 0xff80,       "Request" },
  66         { 0,    NULL },
  67 };
  68
  69
  70 /** Dissects AP-REQ or AP-REP part of password change. */
  71 static void
  72 dissect_kpasswd_ap_req_data(packet_info *pinfo _U_, tvbuff_t *tvb, proto_tree *parent_tree)
  73 {
  74         proto_item *it;
  75         proto_tree *tree=NULL;
  76
  77         if(parent_tree){
  78                 it=proto_tree_add_item(parent_tree, hf_kpasswd_ap_req_data, tvb, 0, -1, ENC_NA);
  79                 tree=proto_item_add_subtree(it, ett_ap_req_data);
  80         }
  81         dissect_kerberos_main(tvb, pinfo, tree, FALSE, NULL);
  82 }
  83
  84
  85 static int dissect_kpasswd_newpassword(proto_tree *tree, tvbuff_t *tvb, int offset, asn1_ctx_t *actx _U_)
  86 {
  87         offset=dissect_ber_octet_string_wcb(FALSE, actx, tree, tvb, offset, hf_kpasswd_newpassword, NULL);
  88
  89         return offset;
  90 }
  91
  92 static ber_old_sequence_t ChangePasswdData_sequence[] = {
  93         { BER_CLASS_CON, 0, 0,
  94                 dissect_kpasswd_newpassword },
  95         { BER_CLASS_CON, 1, BER_FLAGS_OPTIONAL,
  96                 dissect_krb5_cname },
  97         { BER_CLASS_CON, 2, BER_FLAGS_OPTIONAL,
  98                 dissect_krb5_realm },
  99         { 0, 0, 0, NULL }
 100 };
 101
 102 static int
 103 dissect_kpasswd_user_data_request(packet_info *pinfo, tvbuff_t *tvb, proto_tree *tree)
 104 {
 105     int offset=0;
 106         asn1_ctx_t asn1_ctx;
 107         asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, TRUE, pinfo);
 108
 109     offset=dissect_ber_old_sequence(FALSE, &asn1_ctx, tree, tvb, offset, ChangePasswdData_sequence, hf_kpasswd_ChangePasswdData, ett_ChangePasswdData);
 110
 111     return offset;
 112 }
 113
 114 static kerberos_callbacks cb_req[] = {
 115     { KRB_CBTAG_PRIV_USER_DATA,      dissect_kpasswd_user_data_request },
 116     { 0, NULL }
 117 };
 118
 119 #define KRB5_KPASSWD_SUCCESS             0
 120 #define KRB5_KPASSWD_MALFORMED           1
 121 #define KRB5_KPASSWD_HARDERROR           2
 122 #define KRB5_KPASSWD_AUTHERROR           3
 123 #define KRB5_KPASSWD_SOFTERROR           4
 124 #define KRB5_KPASSWD_ACCESSDENIED        5
 125 #define KRB5_KPASSWD_BAD_VERSION         6
 126 #define KRB5_KPASSWD_INITIAL_FLAG_NEEDED 7
 127 static const value_string kpasswd_result_types[] = {
 128     { KRB5_KPASSWD_SUCCESS, "Success" },
 129     { KRB5_KPASSWD_MALFORMED, "Malformed" },
 130     { KRB5_KPASSWD_HARDERROR, "HardError" },
 131     { KRB5_KPASSWD_AUTHERROR, "AuthError" },
 132     { KRB5_KPASSWD_SOFTERROR, "SoftError" },
 133     { KRB5_KPASSWD_ACCESSDENIED, "AccessDenied" },
 134     { KRB5_KPASSWD_BAD_VERSION, "BadVersion" },
 135     { KRB5_KPASSWD_INITIAL_FLAG_NEEDED, "InitialFlagNeeded" },
 136     { 0, NULL }
 137 };
 138
 139 static int
 140 dissect_kpasswd_user_data_reply(packet_info *pinfo, tvbuff_t *tvb, proto_tree *tree)
 141 {
 142     int offset=0;
 143     guint16 result;
 144
 145     /* result */
 146     result = tvb_get_ntohs(tvb, offset);
 147     proto_tree_add_uint(tree, hf_kpasswd_result, tvb, offset, 2, result);
 148     offset+=2;
 149     if (check_col(pinfo->cinfo, COL_INFO))
 150         col_add_str(pinfo->cinfo, COL_INFO,
 151                    val_to_str(result, kpasswd_result_types, "Result: %u"));
 152
 153
 154     /* optional result string */
 155     if(tvb_length_remaining(tvb, offset)){
 156         proto_tree_add_item(tree, hf_kpasswd_result_string, tvb, offset, tvb_length_remaining(tvb, offset), ENC_ASCII|ENC_NA);
 157         offset+=tvb_length_remaining(tvb, offset);
 158     }
 159
 160     return offset;
 161 }
 162
 163
 164 static kerberos_callbacks cb_rep[] = {
 165     { KRB_CBTAG_PRIV_USER_DATA,      dissect_kpasswd_user_data_reply },
 166     { 0, NULL }
 167 };
 168
 169 static gint
 170 dissect_kpasswd_krb_priv_message(packet_info *pinfo _U_, tvbuff_t *tvb, proto_tree *parent_tree, gboolean isrequest)
 171 {
 172         proto_item *it;
 173         proto_tree *tree=NULL;
 174         gint offset;
 175
 176         if(parent_tree){
 177                 it=proto_tree_add_item(parent_tree, hf_kpasswd_krb_priv_message, tvb, 0, -1, ENC_NA);
 178                 tree=proto_item_add_subtree(it, ett_krb_priv_message);
 179         }
 180         if(isrequest){
 181                 offset = dissect_kerberos_main(tvb, pinfo, tree, FALSE, cb_req);
 182         } else {
 183                 offset = dissect_kerberos_main(tvb, pinfo, tree, FALSE, cb_rep);
 184         }
 185
 186         /* offset is bytes consumed in child tvb given to us */
 187         return offset;
 188 }
 189
 190
 191 static gint
 192 dissect_kpasswd_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean have_rm)
 193 {
 194         proto_item *kpasswd_item=NULL;
 195         proto_tree *kpasswd_tree=NULL;
 196         int offset = 0;
 197         guint16 message_len, version, ap_req_len;
 198         tvbuff_t *next_tvb;
 199
 200         /* TCP record mark and length */
 201         guint32 krb_rm = 0;
 202         gint krb_reclen = 0;
 203         gint krb_rm_size = 0;    /* bytes consumed by record mark: 0 or 4 */
 204
 205         col_set_str(pinfo->cinfo, COL_PROTOCOL, "KPASSWD");
 206         col_clear(pinfo->cinfo, COL_INFO);
 207
 208         /* can't pass have_rm to dissect_kerberos_main, so strip rm first */
 209         if (have_rm) {
 210             krb_rm = tvb_get_ntohl(tvb, offset);
 211             krb_reclen = kerberos_rm_to_reclen(krb_rm);
 212             krb_rm_size = 4;
 213             /*
 214              * What is a reasonable size limit?
 215              */
 216             if (krb_reclen > 10 * 1024 * 1024) {
 217                 return (-1);
 218             }
 219             offset += krb_rm_size;
 220         }
 221
 222         /* it might be a KERBEROS ERROR */
 223         if(tvb_get_guint8(tvb, offset)==0x7e){
 224                 /* TCP record mark, if any, not displayed.  But hopefully
 225                    KRB-ERROR dissection will proceed correctly. */
 226                 next_tvb=tvb_new_subset_remaining(tvb, offset);
 227                 return dissect_kerberos_main(next_tvb, pinfo, tree, FALSE, NULL);
 228         }
 229
 230         message_len=tvb_get_ntohs(tvb, offset);
 231         version=tvb_get_ntohs(tvb, offset+2);
 232         ap_req_len=tvb_get_ntohs(tvb, offset+4);
 233         if(tree){
 234                 kpasswd_item=proto_tree_add_item(tree, proto_kpasswd, tvb, offset-krb_rm_size, message_len+krb_rm_size, ENC_NA);
 235                 kpasswd_tree=proto_item_add_subtree(kpasswd_item, ett_kpasswd);
 236                 if (have_rm) {
 237                     show_krb_recordmark(kpasswd_tree, tvb, offset-krb_rm_size, krb_rm);
 238                 }
 239         }
 240
 241         proto_tree_add_uint(kpasswd_tree, hf_kpasswd_message_len, tvb, offset, 2, message_len);
 242         proto_tree_add_uint(kpasswd_tree, hf_kpasswd_version, tvb, offset+2, 2, version);
 243         if (check_col(pinfo->cinfo, COL_INFO))
 244                 col_add_str(pinfo->cinfo, COL_INFO, val_to_str(version, vers_vals, "Unknown command"));
 245         proto_tree_add_uint(kpasswd_tree, hf_kpasswd_ap_req_len, tvb, offset+4, 2, ap_req_len);
 246         offset+=6;
 247
 248         /* AP-REQ / AP-REP data */
 249         next_tvb=tvb_new_subset(tvb, offset, ap_req_len, ap_req_len);
 250         dissect_kpasswd_ap_req_data(pinfo, next_tvb, kpasswd_tree);
 251         offset+=ap_req_len;
 252
 253         /* KRB-PRIV message */
 254         next_tvb=tvb_new_subset_remaining(tvb, offset);
 255         offset += dissect_kpasswd_krb_priv_message(pinfo, next_tvb, kpasswd_tree, (version==0xff80));
 256
 257         proto_item_set_len(kpasswd_item, offset);
 258         return offset;
 259
 260 }
 261
 262 static void
 263 dissect_kpasswd_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 264 {
 265
 266         dissect_kpasswd_common(tvb, pinfo, tree, FALSE);
 267
 268 }
 269
 270 static void
 271 dissect_kpasswd_tcp_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 272 {
 273     pinfo->fragmented = TRUE;
 274     if (dissect_kpasswd_common(tvb, pinfo, tree, TRUE) < 0) {
 275         /*
 276          * The dissector failed to recognize this as a valid
 277          * Kerberos message.  Mark it as a continuation packet.
 278          */
 279         col_set_str(pinfo->cinfo, COL_INFO, "Continuation");
 280     }
 281 }
 282
 283 static void
 284 dissect_kpasswd_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 285 {
 286     col_set_str(pinfo->cinfo, COL_PROTOCOL, "KPASSWD");
 287     col_clear(pinfo->cinfo, COL_INFO);
 288
 289     tcp_dissect_pdus(tvb, pinfo, tree, kpasswd_desegment, 4, get_krb_pdu_len,
 290         dissect_kpasswd_tcp_pdu);
 291 }
 292
 293 void
 294 proto_register_kpasswd(void)
 295 {
 296         static hf_register_info hf[] = {
 297         { &hf_kpasswd_message_len,
 298                 { "Message Length", "kpasswd.message_len", FT_UINT16, BASE_DEC,
 299                 NULL, 0, NULL, HFILL }},
 300         { &hf_kpasswd_ap_req_len,
 301                 { "AP_REQ Length", "kpasswd.ap_req_len", FT_UINT16, BASE_DEC,
 302                 NULL, 0, "Length of AP_REQ data", HFILL }},
 303         { &hf_kpasswd_version,
 304                 { "Version", "kpasswd.version", FT_UINT16, BASE_HEX,
 305                 VALS(vers_vals), 0, NULL, HFILL }},
 306         { &hf_kpasswd_result,
 307                 { "Result", "kpasswd.result", FT_UINT16, BASE_DEC,
 308                 VALS(kpasswd_result_types), 0, NULL, HFILL }},
 309         { &hf_kpasswd_result_string,
 310                 { "Result String", "kpasswd.result_string", FT_STRING, BASE_NONE,
 311                 NULL, 0, NULL, HFILL }},
 312         { &hf_kpasswd_newpassword,
 313                 { "New Password", "kpasswd.new_password", FT_STRING, BASE_NONE,
 314                 NULL, 0, NULL, HFILL }},
 315         { &hf_kpasswd_ap_req_data,
 316                 { "AP_REQ", "kpasswd.ap_req", FT_NONE, BASE_NONE,
 317                 NULL, 0, "AP_REQ structure", HFILL }},
 318         { &hf_kpasswd_krb_priv_message,
 319                 { "KRB-PRIV", "kpasswd.krb_priv", FT_NONE, BASE_NONE,
 320                 NULL, 0, "KRB-PRIV message", HFILL }},
 321         { &hf_kpasswd_ChangePasswdData, {
 322             "ChangePasswdData", "kpasswd.ChangePasswdData", FT_NONE, BASE_NONE,
 323             NULL, 0, "Change Password Data structure", HFILL }},
 324         };
 325
 326         static gint *ett[] = {
 327                 &ett_kpasswd,
 328                 &ett_ap_req_data,
 329                 &ett_krb_priv_message,
 330                 &ett_ChangePasswdData,
 331         };
 332         module_t *kpasswd_module;
 333
 334         proto_kpasswd = proto_register_protocol("MS Kpasswd",
 335                 "Kpasswd", "kpasswd");
 336         proto_register_field_array(proto_kpasswd, hf, array_length(hf));
 337         proto_register_subtree_array(ett, array_length(ett));
 338
 339         /* Register preferences */
 340         kpasswd_module = prefs_register_protocol(proto_kpasswd, NULL);
 341         prefs_register_bool_preference(kpasswd_module, "desegment",
 342             "Reassemble Kpasswd over TCP messages spanning multiple TCP segments",
 343             "Whether the Kpasswd dissector should reassemble messages spanning multiple TCP segments."
 344             " To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\" in the TCP protocol settings.",
 345         &kpasswd_desegment);
 346 }
 347
 348 void
 349 proto_reg_handoff_kpasswd(void)
 350 {
 351         dissector_handle_t kpasswd_handle_udp;
 352         dissector_handle_t kpasswd_handle_tcp;
 353
 354         kpasswd_handle_udp = create_dissector_handle(dissect_kpasswd_udp, proto_kpasswd);
 355         kpasswd_handle_tcp = create_dissector_handle(dissect_kpasswd_tcp, proto_kpasswd);
 356         dissector_add_uint("udp.port", UDP_PORT_KPASSWD, kpasswd_handle_udp);
 357         dissector_add_uint("tcp.port", TCP_PORT_KPASSWD, kpasswd_handle_tcp);
 358
 359 }