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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  26  */
  27
  28 #include "config.h"
  29
  30 #include <epan/packet.h>
  31 #include <epan/asn1.h>
  32 #include "packet-tcp.h"
  33 #include "packet-kerberos.h"
  34 #include "packet-ber.h"
  35 #include <epan/prefs.h>
  36
  37 /* Desegment Kerberos over TCP messages */
  38 static gboolean kpasswd_desegment = TRUE;
  39
  40 static int proto_kpasswd = -1;
  41 static int hf_kpasswd_message_len = -1;
  42 static int hf_kpasswd_version = -1;
  43 static int hf_kpasswd_result = -1;
  44 static int hf_kpasswd_result_string = -1;
  45 static int hf_kpasswd_newpassword = -1;
  46 static int hf_kpasswd_ap_req_len = -1;
  47 static int hf_kpasswd_ap_req_data = -1;
  48 static int hf_kpasswd_krb_priv_message = -1;
  49 static int hf_kpasswd_ChangePasswdData = -1;
  50
  51 static gint ett_kpasswd = -1;
  52 static gint ett_ap_req_data = -1;
  53 static gint ett_krb_priv_message = -1;
  54 static gint ett_ChangePasswdData = -1;
  55
  56
  57 #define UDP_PORT_KPASSWD        464
  58 #define TCP_PORT_KPASSWD        464
  59
  60
  61 static const value_string vers_vals[] = {
  62     { 0x0001, "Reply" },
  63     { 0xff80, "Request" },
  64     { 0,      NULL },
  65 };
  66
  67
  68 /** Dissects AP-REQ or AP-REP part of password change. */
  69 static void
  70 dissect_kpasswd_ap_req_data(packet_info *pinfo _U_, tvbuff_t *tvb, proto_tree *parent_tree)
  71 {
  72     proto_item *it;
  73     proto_tree *tree=NULL;
  74
  75     if(parent_tree){
  76         it=proto_tree_add_item(parent_tree, hf_kpasswd_ap_req_data, tvb, 0, -1, ENC_NA);
  77         tree=proto_item_add_subtree(it, ett_ap_req_data);
  78     }
  79     dissect_kerberos_main(tvb, pinfo, tree, FALSE, NULL);
  80 }
  81
  82
  83 static int dissect_kpasswd_newpassword(proto_tree *tree, tvbuff_t *tvb, int offset, asn1_ctx_t *actx _U_)
  84 {
  85     offset=dissect_ber_octet_string_wcb(FALSE, actx, tree, tvb, offset, hf_kpasswd_newpassword, NULL);
  86     return offset;
  87 }
  88
  89 static ber_old_sequence_t ChangePasswdData_sequence[] = {
  90     { BER_CLASS_CON, 0, 0, dissect_kpasswd_newpassword },
  91     { BER_CLASS_CON, 1, BER_FLAGS_OPTIONAL, dissect_krb5_cname },
  92     { BER_CLASS_CON, 2, BER_FLAGS_OPTIONAL, dissect_krb5_realm },
  93     { 0, 0, 0, NULL }
  94 };
  95
  96 static int
  97 dissect_kpasswd_user_data_request(packet_info *pinfo, tvbuff_t *tvb, proto_tree *tree)
  98 {
  99     int offset=0;
 100     asn1_ctx_t asn1_ctx;
 101     asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, TRUE, pinfo);
 102
 103     offset=dissect_ber_old_sequence(FALSE, &asn1_ctx, tree, tvb, offset, ChangePasswdData_sequence, hf_kpasswd_ChangePasswdData, ett_ChangePasswdData);
 104     return offset;
 105 }
 106
 107 static kerberos_callbacks cb_req[] = {
 108     { KRB_CBTAG_PRIV_USER_DATA, dissect_kpasswd_user_data_request },
 109     { 0, NULL }
 110 };
 111
 112 #define KRB5_KPASSWD_SUCCESS             0
 113 #define KRB5_KPASSWD_MALFORMED           1
 114 #define KRB5_KPASSWD_HARDERROR           2
 115 #define KRB5_KPASSWD_AUTHERROR           3
 116 #define KRB5_KPASSWD_SOFTERROR           4
 117 #define KRB5_KPASSWD_ACCESSDENIED        5
 118 #define KRB5_KPASSWD_BAD_VERSION         6
 119 #define KRB5_KPASSWD_INITIAL_FLAG_NEEDED 7
 120 static const value_string kpasswd_result_types[] = {
 121     { KRB5_KPASSWD_SUCCESS, "Success" },
 122     { KRB5_KPASSWD_MALFORMED, "Malformed" },
 123     { KRB5_KPASSWD_HARDERROR, "HardError" },
 124     { KRB5_KPASSWD_AUTHERROR, "AuthError" },
 125     { KRB5_KPASSWD_SOFTERROR, "SoftError" },
 126     { KRB5_KPASSWD_ACCESSDENIED, "AccessDenied" },
 127     { KRB5_KPASSWD_BAD_VERSION, "BadVersion" },
 128     { KRB5_KPASSWD_INITIAL_FLAG_NEEDED, "InitialFlagNeeded" },
 129     { 0, NULL }
 130 };
 131
 132 static int
 133 dissect_kpasswd_user_data_reply(packet_info *pinfo, tvbuff_t *tvb, proto_tree *tree)
 134 {
 135     int offset=0;
 136     guint16 result;
 137
 138     /* result */
 139     result = tvb_get_ntohs(tvb, offset);
 140     proto_tree_add_uint(tree, hf_kpasswd_result, tvb, offset, 2, result);
 141     offset+=2;
 142     col_add_str(pinfo->cinfo, COL_INFO,
 143         val_to_str(result, kpasswd_result_types, "Result: %u"));
 144
 145
 146     /* optional result string */
 147     if(tvb_reported_length_remaining(tvb, offset) > 0){
 148         proto_tree_add_item(tree, hf_kpasswd_result_string, tvb, offset, tvb_reported_length_remaining(tvb, offset), ENC_ASCII|ENC_NA);
 149         offset = tvb_reported_length(tvb);
 150     }
 151
 152     return offset;
 153 }
 154
 155
 156 static kerberos_callbacks cb_rep[] = {
 157     { KRB_CBTAG_PRIV_USER_DATA, dissect_kpasswd_user_data_reply },
 158     { 0, NULL }
 159 };
 160
 161 static gint
 162 dissect_kpasswd_krb_priv_message(packet_info *pinfo _U_, tvbuff_t *tvb, proto_tree *parent_tree, gboolean isrequest)
 163 {
 164     proto_item *it;
 165     proto_tree *tree=NULL;
 166     gint offset;
 167
 168     if(parent_tree){
 169         it=proto_tree_add_item(parent_tree, hf_kpasswd_krb_priv_message, tvb, 0, -1, ENC_NA);
 170         tree=proto_item_add_subtree(it, ett_krb_priv_message);
 171     }
 172     if(isrequest){
 173         offset = dissect_kerberos_main(tvb, pinfo, tree, FALSE, cb_req);
 174     } else {
 175         offset = dissect_kerberos_main(tvb, pinfo, tree, FALSE, cb_rep);
 176     }
 177
 178     /* offset is bytes consumed in child tvb given to us */
 179     return offset;
 180 }
 181
 182
 183 static gint
 184 dissect_kpasswd_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean have_rm)
 185 {
 186     proto_item *kpasswd_item=NULL;
 187     proto_tree *kpasswd_tree=NULL;
 188     int offset = 0;
 189     guint16 message_len, version, ap_req_len;
 190     tvbuff_t *next_tvb;
 191
 192     /* TCP record mark and length */
 193     guint32 krb_rm = 0;
 194     gint krb_reclen = 0;
 195     gint krb_rm_size = 0;    /* bytes consumed by record mark: 0 or 4 */
 196
 197     col_set_str(pinfo->cinfo, COL_PROTOCOL, "KPASSWD");
 198     col_clear(pinfo->cinfo, COL_INFO);
 199
 200     /* can't pass have_rm to dissect_kerberos_main, so strip rm first */
 201     if (have_rm) {
 202         krb_rm = tvb_get_ntohl(tvb, offset);
 203         krb_reclen = kerberos_rm_to_reclen(krb_rm);
 204         krb_rm_size = 4;
 205         /*
 206          * What is a reasonable size limit?
 207          */
 208         if (krb_reclen > 10 * 1024 * 1024) {
 209             return (-1);
 210         }
 211         offset += krb_rm_size;
 212     }
 213
 214     /* it might be a KERBEROS ERROR */
 215     if(tvb_get_guint8(tvb, offset)==0x7e){
 216         /* TCP record mark, if any, not displayed.  But hopefully
 217          * KRB-ERROR dissection will proceed correctly. */
 218         next_tvb=tvb_new_subset_remaining(tvb, offset);
 219         return dissect_kerberos_main(next_tvb, pinfo, tree, FALSE, NULL);
 220     }
 221
 222     message_len=tvb_get_ntohs(tvb, offset);
 223     version=tvb_get_ntohs(tvb, offset+2);
 224     ap_req_len=tvb_get_ntohs(tvb, offset+4);
 225     if(tree){
 226         kpasswd_item=proto_tree_add_item(tree, proto_kpasswd, tvb, offset-krb_rm_size, message_len+krb_rm_size, ENC_NA);
 227         kpasswd_tree=proto_item_add_subtree(kpasswd_item, ett_kpasswd);
 228         if (have_rm) {
 229             show_krb_recordmark(kpasswd_tree, tvb, offset-krb_rm_size, krb_rm);
 230         }
 231     }
 232
 233     proto_tree_add_uint(kpasswd_tree, hf_kpasswd_message_len, tvb, offset, 2, message_len);
 234     proto_tree_add_uint(kpasswd_tree, hf_kpasswd_version, tvb, offset+2, 2, version);
 235     col_set_str(pinfo->cinfo, COL_INFO, val_to_str_const(version, vers_vals, "Unknown command"));
 236     proto_tree_add_uint(kpasswd_tree, hf_kpasswd_ap_req_len, tvb, offset+4, 2, ap_req_len);
 237     offset+=6;
 238
 239     /* AP-REQ / AP-REP data */
 240     next_tvb=tvb_new_subset(tvb, offset, ap_req_len, ap_req_len);
 241     dissect_kpasswd_ap_req_data(pinfo, next_tvb, kpasswd_tree);
 242     offset+=ap_req_len;
 243
 244     /* KRB-PRIV message */
 245     next_tvb=tvb_new_subset_remaining(tvb, offset);
 246     offset += dissect_kpasswd_krb_priv_message(pinfo, next_tvb, kpasswd_tree, (version==0xff80));
 247
 248     proto_item_set_len(kpasswd_item, offset);
 249     return offset;
 250
 251 }
 252
 253 static void
 254 dissect_kpasswd_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 255 {
 256     dissect_kpasswd_common(tvb, pinfo, tree, FALSE);
 257 }
 258
 259 static int
 260 dissect_kpasswd_tcp_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
 261 {
 262     pinfo->fragmented = TRUE;
 263     if (dissect_kpasswd_common(tvb, pinfo, tree, TRUE) < 0) {
 264         /*
 265          * The dissector failed to recognize this as a valid
 266          * Kerberos message.  Mark it as a continuation packet.
 267          */
 268         col_set_str(pinfo->cinfo, COL_INFO, "Continuation");
 269     }
 270     return tvb_length(tvb);
 271 }
 272
 273 static int
 274 dissect_kpasswd_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
 275 {
 276     col_set_str(pinfo->cinfo, COL_PROTOCOL, "KPASSWD");
 277     col_clear(pinfo->cinfo, COL_INFO);
 278
 279     tcp_dissect_pdus(tvb, pinfo, tree, kpasswd_desegment, 4, get_krb_pdu_len, dissect_kpasswd_tcp_pdu, data);
 280     return tvb_length(tvb);
 281 }
 282
 283 void
 284 proto_register_kpasswd(void)
 285 {
 286     static hf_register_info hf[] = {
 287     { &hf_kpasswd_message_len,
 288         { "Message Length", "kpasswd.message_len", FT_UINT16, BASE_DEC,
 289         NULL, 0, NULL, HFILL }},
 290     { &hf_kpasswd_ap_req_len,
 291         { "AP_REQ Length", "kpasswd.ap_req_len", FT_UINT16, BASE_DEC,
 292         NULL, 0, "Length of AP_REQ data", HFILL }},
 293     { &hf_kpasswd_version,
 294         { "Version", "kpasswd.version", FT_UINT16, BASE_HEX,
 295         VALS(vers_vals), 0, NULL, HFILL }},
 296     { &hf_kpasswd_result,
 297         { "Result", "kpasswd.result", FT_UINT16, BASE_DEC,
 298         VALS(kpasswd_result_types), 0, NULL, HFILL }},
 299     { &hf_kpasswd_result_string,
 300         { "Result String", "kpasswd.result_string", FT_STRING, BASE_NONE,
 301         NULL, 0, NULL, HFILL }},
 302     { &hf_kpasswd_newpassword,
 303         { "New Password", "kpasswd.new_password", FT_STRING, BASE_NONE,
 304         NULL, 0, NULL, HFILL }},
 305     { &hf_kpasswd_ap_req_data,
 306         { "AP_REQ", "kpasswd.ap_req", FT_NONE, BASE_NONE,
 307         NULL, 0, "AP_REQ structure", HFILL }},
 308     { &hf_kpasswd_krb_priv_message,
 309         { "KRB-PRIV", "kpasswd.krb_priv", FT_NONE, BASE_NONE,
 310         NULL, 0, "KRB-PRIV message", HFILL }},
 311     { &hf_kpasswd_ChangePasswdData, {
 312         "ChangePasswdData", "kpasswd.ChangePasswdData", FT_NONE, BASE_NONE,
 313         NULL, 0, "Change Password Data structure", HFILL }},
 314     };
 315
 316     static gint *ett[] = {
 317         &ett_kpasswd,
 318         &ett_ap_req_data,
 319         &ett_krb_priv_message,
 320         &ett_ChangePasswdData,
 321     };
 322         module_t *kpasswd_module;
 323
 324     proto_kpasswd = proto_register_protocol("MS Kpasswd",
 325         "Kpasswd", "kpasswd");
 326     proto_register_field_array(proto_kpasswd, hf, array_length(hf));
 327     proto_register_subtree_array(ett, array_length(ett));
 328
 329     /* Register preferences */
 330     kpasswd_module = prefs_register_protocol(proto_kpasswd, NULL);
 331     prefs_register_bool_preference(kpasswd_module, "desegment",
 332         "Reassemble Kpasswd over TCP messages spanning multiple TCP segments",
 333         "Whether the Kpasswd dissector should reassemble messages spanning multiple TCP segments."
 334         " To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\" in the TCP protocol settings.",
 335         &kpasswd_desegment);
 336 }
 337
 338 void
 339 proto_reg_handoff_kpasswd(void)
 340 {
 341     dissector_handle_t kpasswd_handle_udp;
 342     dissector_handle_t kpasswd_handle_tcp;
 343
 344     kpasswd_handle_udp = create_dissector_handle(dissect_kpasswd_udp, proto_kpasswd);
 345     kpasswd_handle_tcp = new_create_dissector_handle(dissect_kpasswd_tcp, proto_kpasswd);
 346     dissector_add_uint("udp.port", UDP_PORT_KPASSWD, kpasswd_handle_udp);
 347     dissector_add_uint("tcp.port", TCP_PORT_KPASSWD, kpasswd_handle_tcp);
 348 }