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wireshark/asn1/spnego/packet-spnego-template.c

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/* packet-spnego.c
* Routines for the simple and protected GSS-API negotiation mechanism
* as described in RFC 2478.
* Copyright 2002, Tim Potter <tpot@samba.org>
* Copyright 2002, Richard Sharpe <rsharpe@ns.aus.com>
* Copyright 2003, Richard Sharpe <rsharpe@richardsharpe.com>
* Copyright 2005, Ronnie Sahlberg (krb decryption)
* Copyright 2005, Anders Broman (converted to asn2eth generated dissector)
*
* $Id$
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/* The heimdal code for decryption of GSSAPI wrappers using heimdal comes from
Heimdal 1.6 and has been modified for ethereal's requirements.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <glib.h>
#include <epan/packet.h>
#include "packet-dcerpc.h"
#include "packet-gssapi.h"
#include "packet-kerberos.h"
#include <epan/crypt-rc4.h>
#include <epan/conversation.h>
#include <epan/emem.h>
#include <stdio.h>
#include <string.h>
#include "packet-ber.h"
#define PNAME "Simple Protected Negotiation"
#define PSNAME "SPNEGO"
#define PFNAME "spnego"
/* Initialize the protocol and registered fields */
static int proto_spnego = -1;
static int proto_spnego_krb5 = -1;
static int hf_spnego = -1;
static int hf_spnego_wraptoken = -1;
static int hf_spnego_krb5_oid;
static int hf_spnego_krb5 = -1;
static int hf_spnego_krb5_tok_id = -1;
static int hf_spnego_krb5_sgn_alg = -1;
static int hf_spnego_krb5_seal_alg = -1;
static int hf_spnego_krb5_snd_seq = -1;
static int hf_spnego_krb5_sgn_cksum = -1;
static int hf_spnego_krb5_confounder = -1;
#include "packet-spnego-hf.c"
/* Global variables */
static const char *MechType_oid;
gssapi_oid_value *next_level_value;
gboolean saw_mechanism = FALSE;
/* Initialize the subtree pointers */
static gint ett_spnego;
static gint ett_spnego_wraptoken;
static gint ett_spnego_krb5 = -1;
#include "packet-spnego-ett.c"
static dissector_handle_t data_handle;
/*
* Unfortunately, we have to have a forward declaration of this,
* as the code generated by asn2eth includes a call before the
* definition.
*/
static int dissect_spnego_PrincipalSeq(gboolean implicit_tag, tvbuff_t *tvb,
int offset, packet_info *pinfo,
proto_tree *tree, int hf_index);
#include "packet-spnego-fn.c"
/*
* This is the SPNEGO KRB5 dissector. It is not true KRB5, but some ASN.1
* wrapped blob with an OID, USHORT token ID, and a Ticket, that is also
* ASN.1 wrapped by the looks of it. It conforms to RFC1964.
*/
#define KRB_TOKEN_AP_REQ 0x0001
#define KRB_TOKEN_AP_REP 0x0002
#define KRB_TOKEN_AP_ERR 0x0003
#define KRB_TOKEN_GETMIC 0x0101
#define KRB_TOKEN_WRAP 0x0102
#define KRB_TOKEN_DELETE_SEC_CONTEXT 0x0201
static const value_string spnego_krb5_tok_id_vals[] = {
{ KRB_TOKEN_AP_REQ, "KRB5_AP_REQ"},
{ KRB_TOKEN_AP_REP, "KRB5_AP_REP"},
{ KRB_TOKEN_AP_ERR, "KRB5_ERROR"},
{ KRB_TOKEN_GETMIC, "KRB5_GSS_GetMIC" },
{ KRB_TOKEN_WRAP, "KRB5_GSS_Wrap" },
{ KRB_TOKEN_DELETE_SEC_CONTEXT, "KRB5_GSS_Delete_sec_context" },
{ 0, NULL}
};
#define KRB_SGN_ALG_DES_MAC_MD5 0x0000
#define KRB_SGN_ALG_MD2_5 0x0001
#define KRB_SGN_ALG_DES_MAC 0x0002
#define KRB_SGN_ALG_HMAC 0x0011
static const value_string spnego_krb5_sgn_alg_vals[] = {
{ KRB_SGN_ALG_DES_MAC_MD5, "DES MAC MD5"},
{ KRB_SGN_ALG_MD2_5, "MD2.5"},
{ KRB_SGN_ALG_DES_MAC, "DES MAC"},
{ KRB_SGN_ALG_HMAC, "HMAC"},
{ 0, NULL}
};
#define KRB_SEAL_ALG_DES_CBC 0x0000
#define KRB_SEAL_ALG_RC4 0x0010
#define KRB_SEAL_ALG_NONE 0xffff
static const value_string spnego_krb5_seal_alg_vals[] = {
{ KRB_SEAL_ALG_DES_CBC, "DES CBC"},
{ KRB_SEAL_ALG_RC4, "RC4"},
{ KRB_SEAL_ALG_NONE, "None"},
{ 0, NULL}
};
/*
* XXX - is this for SPNEGO or just GSS-API?
* RFC 1964 is "The Kerberos Version 5 GSS-API Mechanism"; presumably one
* can directly designate Kerberos V5 as a mechanism in GSS-API, rather
* than designating SPNEGO as the mechanism, offering Kerberos V5, and
* getting it accepted.
*/
static int
dissect_spnego_krb5_getmic_base(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree);
static int
dissect_spnego_krb5_wrap_base(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree, guint16 token_id);
static void
dissect_spnego_krb5(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_item *item;
proto_tree *subtree;
int offset = 0;
guint16 token_id;
const char *oid;
gssapi_oid_value *value;
tvbuff_t *krb5_tvb;
gint8 class;
gboolean pc, ind = 0;
gint32 tag;
guint32 len;
item = proto_tree_add_item(tree, hf_spnego_krb5, tvb, offset,
-1, FALSE);
subtree = proto_item_add_subtree(item, ett_spnego_krb5);
/*
* The KRB5 blob conforms to RFC1964:
* [APPLICATION 0] {
* OID,
* USHORT (0x0001 == AP-REQ, 0x0002 == AP-REP, 0x0003 == ERROR),
* OCTET STRING }
*
* However, for some protocols, the KRB5 blob starts at the SHORT
* and has no DER encoded header etc.
*
* It appears that for some other protocols the KRB5 blob is just
* a Kerberos message, with no [APPLICATION 0] header, no OID,
* and no USHORT.
*
* So:
*
* If we see an [APPLICATION 0] HEADER, we show the OID and
* the USHORT, and then dissect the rest as a Kerberos message.
*
* If we see an [APPLICATION 14] or [APPLICATION 15] header,
* we assume it's an AP-REQ or AP-REP message, and dissect
* it all as a Kerberos message.
*
* Otherwise, we show the USHORT, and then dissect the rest
* as a Kerberos message.
*/
/*
* Get the first header ...
*/
get_ber_identifier(tvb, offset, &class, &pc, &tag);
if (class == BER_CLASS_APP && pc) {
/*
* [APPLICATION <tag>]
*/
offset = dissect_ber_identifier(pinfo, subtree, tvb, offset, &class, &pc, &tag);
offset = dissect_ber_length(pinfo, subtree, tvb, offset, &len, &ind);
switch (tag) {
case 0:
/*
* [APPLICATION 0]
*/
/* Next, the OID */
offset=dissect_ber_object_identifier_str(FALSE, pinfo, subtree, tvb, offset, hf_spnego_krb5_oid, &oid);
value = gssapi_lookup_oid_str(oid);
token_id = tvb_get_letohs(tvb, offset);
proto_tree_add_uint(subtree, hf_spnego_krb5_tok_id, tvb, offset, 2,
token_id);
offset += 2;
break;
case 14: /* [APPLICATION 14] */
case 15: /* [APPLICATION 15] */
/*
* No token ID - just dissect as a Kerberos message and
* return.
*/
offset = dissect_kerberos_main(tvb, pinfo, subtree, FALSE, NULL);
return;
default:
proto_tree_add_text(subtree, tvb, offset, 0,
"Unknown header (class=%d, pc=%d, tag=%d)",
class, pc, tag);
goto done;
}
} else {
/* Next, the token ID ... */
token_id = tvb_get_letohs(tvb, offset);
proto_tree_add_uint(subtree, hf_spnego_krb5_tok_id, tvb, offset, 2,
token_id);
offset += 2;
}
switch (token_id) {
case KRB_TOKEN_AP_REQ:
case KRB_TOKEN_AP_REP:
case KRB_TOKEN_AP_ERR:
krb5_tvb = tvb_new_subset(tvb, offset, -1, -1);
offset = dissect_kerberos_main(krb5_tvb, pinfo, subtree, FALSE, NULL);
break;
case KRB_TOKEN_GETMIC:
offset = dissect_spnego_krb5_getmic_base(tvb, offset, pinfo, subtree);
break;
case KRB_TOKEN_WRAP:
offset = dissect_spnego_krb5_wrap_base(tvb, offset, pinfo, subtree, token_id);
break;
case KRB_TOKEN_DELETE_SEC_CONTEXT:
break;
default:
break;
}
done:
return;
}
#ifdef HAVE_KERBEROS
#include <epan/crypt-md5.h>
#ifndef KEYTYPE_ARCFOUR_56
# define KEYTYPE_ARCFOUR_56 24
#endif
/* XXX - We should probably do a configure-time check for this instead */
#ifndef KRB5_KU_USAGE_SEAL
# define KRB5_KU_USAGE_SEAL 22
#endif
static int
arcfour_mic_key(void *key_data, size_t key_size, int key_type,
void *cksum_data, size_t cksum_size,
void *key6_data)
{
guint8 k5_data[16];
guint8 T[4];
memset(T, 0, 4);
if (key_type == KEYTYPE_ARCFOUR_56) {
guint8 L40[14] = "fortybits";
memcpy(L40 + 10, T, sizeof(T));
md5_hmac(
L40, 14,
key_data,
key_size,
k5_data);
memset(&k5_data[7], 0xAB, 9);
} else {
md5_hmac(
T, 4,
key_data,
key_size,
k5_data);
}
md5_hmac(
cksum_data, cksum_size,
k5_data,
16,
key6_data);
return 0;
}
static int
usage2arcfour(int usage)
{
switch (usage) {
case 3: /*KRB5_KU_AS_REP_ENC_PART 3 */
case 9: /*KRB5_KU_TGS_REP_ENC_PART_SUB_KEY 9 */
return 8;
case 22: /*KRB5_KU_USAGE_SEAL 22 */
return 13;
case 23: /*KRB5_KU_USAGE_SIGN 23 */
return 15;
case 24: /*KRB5_KU_USAGE_SEQ 24 */
return 0;
default :
return 0;
}
}
static int
arcfour_mic_cksum(guint8 *key_data, int key_length,
unsigned usage,
guint8 sgn_cksum[8],
const void *v1, size_t l1,
const void *v2, size_t l2,
const void *v3, size_t l3)
{
const guint8 signature[] = "signaturekey";
guint8 ksign_c[16];
unsigned char t[4];
md5_state_t ms;
unsigned char digest[16];
int rc4_usage;
guint8 cksum[16];
rc4_usage=usage2arcfour(usage);
md5_hmac(signature, sizeof(signature),
key_data, key_length,
ksign_c);
md5_init(&ms);
t[0] = (rc4_usage >> 0) & 0xFF;
t[1] = (rc4_usage >> 8) & 0xFF;
t[2] = (rc4_usage >> 16) & 0xFF;
t[3] = (rc4_usage >> 24) & 0xFF;
md5_append(&ms, t, 4);
md5_append(&ms, v1, l1);
md5_append(&ms, v2, l2);
md5_append(&ms, v3, l3);
md5_finish(&ms, digest);
md5_hmac(digest, 16, ksign_c, 16, cksum);
memcpy(sgn_cksum, cksum, 8);
return 0;
}
/*
* Verify padding of a gss wrapped message and return its length.
*/
static int
gssapi_verify_pad(unsigned char *wrapped_data, int wrapped_length,
size_t datalen,
size_t *padlen)
{
unsigned char *pad;
size_t padlength;
int i;
pad = wrapped_data + wrapped_length - 1;
padlength = *pad;
if (padlength > datalen)
return 1;
for (i = padlength; i > 0 && *pad == padlength; i--, pad--)
;
if (i != 0)
return 2;
*padlen = padlength;
return 0;
}
static int
decrypt_arcfour(packet_info *pinfo,
guint8 *input_message_buffer,
guint8 *output_message_buffer,
guint8 *key_value, int key_size, int key_type)
{
guint8 Klocaldata[16];
int ret;
gint32 seq_number;
size_t datalen;
guint8 k6_data[16], SND_SEQ[8], Confounder[8];
guint8 cksum_data[8];
int cmp;
int conf_flag;
size_t padlen = 0;
datalen = tvb_length(pinfo->gssapi_encrypted_tvb);
if(tvb_get_ntohs(pinfo->gssapi_wrap_tvb, 4)==0x1000){
conf_flag=1;
} else if (tvb_get_ntohs(pinfo->gssapi_wrap_tvb, 4)==0xffff){
conf_flag=0;
} else {
return -3;
}
if(tvb_get_ntohs(pinfo->gssapi_wrap_tvb, 6)!=0xffff){
return -4;
}
ret = arcfour_mic_key(key_value, key_size, key_type,
(void *)tvb_get_ptr(pinfo->gssapi_wrap_tvb, 16, 8),
8, /* SGN_CKSUM */
k6_data);
if (ret) {
return -5;
}
{
rc4_state_struct rc4_state;
crypt_rc4_init(&rc4_state, k6_data, sizeof(k6_data));
memcpy(SND_SEQ, (unsigned char *)tvb_get_ptr(pinfo->gssapi_wrap_tvb, 8, 8), 8);
crypt_rc4(&rc4_state, SND_SEQ, 8);
memset(k6_data, 0, sizeof(k6_data));
}
seq_number=g_ntohl(*((guint32 *)SND_SEQ));
cmp = memcmp(&SND_SEQ[4], "\xff\xff\xff\xff", 4);
if(cmp){
cmp = memcmp(&SND_SEQ[4], "\x00\x00\x00\x00", 4);
}
if (cmp != 0) {
return -6;
}
{
int i;
for (i = 0; i < 16; i++)
Klocaldata[i] = ((guint8 *)key_value)[i] ^ 0xF0;
}
ret = arcfour_mic_key(Klocaldata,sizeof(Klocaldata),key_type,
SND_SEQ, 4,
k6_data);
memset(Klocaldata, 0, sizeof(Klocaldata));
if (ret) {
return -7;
}
if(conf_flag) {
rc4_state_struct rc4_state;
crypt_rc4_init(&rc4_state, k6_data, sizeof(k6_data));
memcpy(Confounder, (unsigned char *)tvb_get_ptr(pinfo->gssapi_wrap_tvb, 24, 8), 8);
crypt_rc4(&rc4_state, Confounder, 8);
memcpy(output_message_buffer, input_message_buffer, datalen);
crypt_rc4(&rc4_state, output_message_buffer, datalen);
} else {
memcpy(Confounder,
tvb_get_ptr(pinfo->gssapi_wrap_tvb, 24, 8),
8); /* Confounder */
memcpy(output_message_buffer,
input_message_buffer,
datalen);
}
memset(k6_data, 0, sizeof(k6_data));
/* only normal (i.e. non DCE style wrapping use padding ? */
if(pinfo->decrypt_gssapi_tvb==DECRYPT_GSSAPI_NORMAL){
ret = gssapi_verify_pad(output_message_buffer,datalen,datalen, &padlen);
if (ret) {
return -9;
}
datalen -= padlen;
}
/* dont know what the checksum looks like for dce style gssapi */
if(pinfo->decrypt_gssapi_tvb==DECRYPT_GSSAPI_NORMAL){
ret = arcfour_mic_cksum(key_value, key_size,
KRB5_KU_USAGE_SEAL,
cksum_data,
tvb_get_ptr(pinfo->gssapi_wrap_tvb, 0, 8), 8,
Confounder, sizeof(Confounder),
output_message_buffer,
datalen + padlen);
if (ret) {
return -10;
}
cmp = memcmp(cksum_data,
tvb_get_ptr(pinfo->gssapi_wrap_tvb, 16, 8),
8); /* SGN_CKSUM */
if (cmp) {
return -11;
}
}
return datalen;
}
#if defined(HAVE_HEIMDAL_KERBEROS) || defined(HAVE_MIT_KERBEROS)
static void
decrypt_gssapi_krb_arcfour_wrap(proto_tree *tree, packet_info *pinfo, tvbuff_t *tvb, int keytype)
{
int ret;
enc_key_t *ek;
int length;
const guint8 *original_data;
static int omb_index=0;
static guint8 *omb_arr[4]={NULL,NULL,NULL,NULL};
static guint8 *cryptocopy=NULL; /* workaround for pre-0.6.1 heimdal bug */
guint8 *output_message_buffer;
omb_index++;
if(omb_index>=4){
omb_index=0;
}
output_message_buffer=omb_arr[omb_index];
length=tvb_length(pinfo->gssapi_encrypted_tvb);
original_data=tvb_get_ptr(pinfo->gssapi_encrypted_tvb, 0, length);
/* dont do anything if we are not attempting to decrypt data */
/*
if(!krb_decrypt){
return;
}
*/
/* XXX we should only do this for first time, then store somewhere */
/* XXX We also need to re-read the keytab when the preference changes */
cryptocopy=ep_alloc(length);
if(output_message_buffer){
g_free(output_message_buffer);
output_message_buffer=NULL;
}
output_message_buffer=g_malloc(length);
for(ek=enc_key_list;ek;ek=ek->next){
/* shortcircuit and bail out if enctypes are not matching */
if(ek->keytype!=keytype){
continue;
}
/* pre-0.6.1 versions of Heimdal would sometimes change
the cryptotext data even when the decryption failed.
This would obviously not work since we iterate over the
keys. So just give it a copy of the crypto data instead.
This has been seen for RC4-HMAC blobs.
*/
memcpy(cryptocopy, original_data, length);
ret=decrypt_arcfour(pinfo,
cryptocopy,
output_message_buffer,
ek->keyvalue,
ek->keylength,
ek->keytype
);
if (ret >= 0) {
proto_tree_add_text(tree, NULL, 0, 0, "[Decrypted using: %s]", ek->key_origin);
pinfo->gssapi_decrypted_tvb=tvb_new_real_data(
output_message_buffer,
ret, ret);
tvb_set_child_real_data_tvbuff(tvb, pinfo->gssapi_decrypted_tvb);
add_new_data_source(pinfo, pinfo->gssapi_decrypted_tvb, "Decrypted GSS-Krb5");
return;
}
}
return;
}
#endif /* HAVE_HEIMDAL_KERBEROS || HAVE_MIT_KERBEROS */
#endif
/*
* XXX - This is for GSSAPI Wrap tokens ...
*/
static int
dissect_spnego_krb5_wrap_base(tvbuff_t *tvb, int offset, packet_info *pinfo
#ifndef HAVE_KERBEROS
_U_
#endif
, proto_tree *tree, guint16 token_id
#ifndef HAVE_KERBEROS
_U_
#endif
)
{
guint16 sgn_alg, seal_alg;
#ifdef HAVE_KERBEROS
int start_offset=offset;
#endif
/*
* The KRB5 blob conforms to RFC1964:
* USHORT (0x0102 == GSS_Wrap)
* and so on }
*/
/* Now, the sign and seal algorithms ... */
sgn_alg = tvb_get_letohs(tvb, offset);
proto_tree_add_uint(tree, hf_spnego_krb5_sgn_alg, tvb, offset, 2,
sgn_alg);
offset += 2;
seal_alg = tvb_get_letohs(tvb, offset);
proto_tree_add_uint(tree, hf_spnego_krb5_seal_alg, tvb, offset, 2,
seal_alg);
offset += 2;
/* Skip the filler */
offset += 2;
/* Encrypted sequence number */
proto_tree_add_item(tree, hf_spnego_krb5_snd_seq, tvb, offset, 8,
TRUE);
offset += 8;
/* Checksum of plaintext padded data */
proto_tree_add_item(tree, hf_spnego_krb5_sgn_cksum, tvb, offset, 8,
TRUE);
offset += 8;
/*
* At least according to draft-brezak-win2k-krb-rc4-hmac-04,
* if the signing algorithm is KRB_SGN_ALG_HMAC, there's an
* extra 8 bytes of "Random confounder" after the checksum.
* It certainly confounds code expecting all Kerberos 5
* GSS_Wrap() tokens to look the same....
*/
if (sgn_alg == KRB_SGN_ALG_HMAC) {
proto_tree_add_item(tree, hf_spnego_krb5_confounder, tvb, offset, 8,
TRUE);
offset += 8;
}
/* Is the data encrypted? */
pinfo->gssapi_data_encrypted=(seal_alg!=KRB_SEAL_ALG_NONE);
#ifdef HAVE_KERBEROS
#define GSS_ARCFOUR_WRAP_TOKEN_SIZE 32
if(pinfo->decrypt_gssapi_tvb){
/* if the caller did not provide a tvb, then we just use
whatever is left of our current tvb.
*/
if(!pinfo->gssapi_encrypted_tvb){
int len;
len=tvb_reported_length_remaining(tvb,offset);
if(len>tvb_length_remaining(tvb, offset)){
/* no point in trying to decrypt,
we dont have the full pdu.
*/
return offset;
}
pinfo->gssapi_encrypted_tvb = tvb_new_subset(
tvb, offset, len, len);
}
/* if this is KRB5 wrapped rc4-hmac */
if((token_id==KRB_TOKEN_WRAP)
&&(sgn_alg==KRB_SGN_ALG_HMAC)
&&(seal_alg==KRB_SEAL_ALG_RC4)){
/* do we need to create a tvb for the wrapper
as well ?
*/
if(!pinfo->gssapi_wrap_tvb){
pinfo->gssapi_wrap_tvb = tvb_new_subset(
tvb, start_offset-2,
GSS_ARCFOUR_WRAP_TOKEN_SIZE,
GSS_ARCFOUR_WRAP_TOKEN_SIZE);
}
#if defined(HAVE_HEIMDAL_KERBEROS) || defined(HAVE_MIT_KERBEROS)
decrypt_gssapi_krb_arcfour_wrap(tree,
pinfo,
tvb,
23 /* rc4-hmac */);
#endif /* HAVE_HEIMDAL_KERBEROS || HAVE_MIT_KERBEROS */
}
}
#endif
/*
* Return the offset past the checksum, so that we know where
* the data we're wrapped around starts. Also, set the length
* of our top-level item to that offset, so it doesn't cover
* the data we're wrapped around.
*
* Note that for DCERPC the GSSAPI blobs comes after the data it wraps,
* not before.
*/
return offset;
}
/*
* XXX - This is for GSSAPI GetMIC tokens ...
*/
static int
dissect_spnego_krb5_getmic_base(tvbuff_t *tvb, int offset, packet_info *pinfo _U_, proto_tree *tree)
{
guint16 sgn_alg;
/*
* The KRB5 blob conforms to RFC1964:
* USHORT (0x0101 == GSS_GetMIC)
* and so on }
*/
/* Now, the sign algorithm ... */
sgn_alg = tvb_get_letohs(tvb, offset);
proto_tree_add_uint(tree, hf_spnego_krb5_sgn_alg, tvb, offset, 2,
sgn_alg);
offset += 2;
/* Skip the filler */
offset += 4;
/* Encrypted sequence number */
proto_tree_add_item(tree, hf_spnego_krb5_snd_seq, tvb, offset, 8,
TRUE);
offset += 8;
/* Checksum of plaintext padded data */
proto_tree_add_item(tree, hf_spnego_krb5_sgn_cksum, tvb, offset, 8,
TRUE);
offset += 8;
/*
* At least according to draft-brezak-win2k-krb-rc4-hmac-04,
* if the signing algorithm is KRB_SGN_ALG_HMAC, there's an
* extra 8 bytes of "Random confounder" after the checksum.
* It certainly confounds code expecting all Kerberos 5
* GSS_Wrap() tokens to look the same....
*/
if (sgn_alg == KRB_SGN_ALG_HMAC) {
proto_tree_add_item(tree, hf_spnego_krb5_confounder, tvb, offset, 8,
TRUE);
offset += 8;
}
/*
* Return the offset past the checksum, so that we know where
* the data we're wrapped around starts. Also, set the length
* of our top-level item to that offset, so it doesn't cover
* the data we're wrapped around.
*/
return offset;
}
/*
* XXX - is this for SPNEGO or just GSS-API?
* RFC 1964 is "The Kerberos Version 5 GSS-API Mechanism"; presumably one
* can directly designate Kerberos V5 as a mechanism in GSS-API, rather
* than designating SPNEGO as the mechanism, offering Kerberos V5, and
* getting it accepted.
*/
static int
dissect_spnego_krb5_wrap(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
{
proto_item *item;
proto_tree *subtree;
int offset = 0;
guint16 token_id;
item = proto_tree_add_item(tree, hf_spnego_krb5, tvb, 0, -1, FALSE);
subtree = proto_item_add_subtree(item, ett_spnego_krb5);
/*
* The KRB5 blob conforms to RFC1964:
* USHORT (0x0102 == GSS_Wrap)
* and so on }
*/
/* First, the token ID ... */
token_id = tvb_get_letohs(tvb, offset);
proto_tree_add_uint(subtree, hf_spnego_krb5_tok_id, tvb, offset, 2,
token_id);
offset += 2;
offset = dissect_spnego_krb5_wrap_base(tvb, offset, pinfo, subtree, token_id);
/*
* Return the offset past the checksum, so that we know where
* the data we're wrapped around starts. Also, set the length
* of our top-level item to that offset, so it doesn't cover
* the data we're wrapped around.
*/
proto_item_set_len(item, offset);
return offset;
}
/* Spnego stuff from here */
static int
dissect_spnego_wrap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_item *item;
proto_tree *subtree;
int offset = 0;
/*
* We need this later, so lets get it now ...
* It has to be per-frame as there can be more than one GSS-API
* negotiation in a conversation.
*/
item = proto_tree_add_item(tree, hf_spnego, tvb, offset,
-1, FALSE);
subtree = proto_item_add_subtree(item, ett_spnego);
/*
* The TVB contains a [0] header and a sequence that consists of an
* object ID and a blob containing the data ...
* XXX - is this RFC 2743's "Mechanism-Independent Token Format",
* with the "optional" "use in non-initial tokens" being chosen.
* ASN1 code addet to spnego.asn to handle this.
*/
offset = dissect_spnego_InitialContextToken(FALSE, tvb, offset, pinfo , subtree, -1);
return offset;
}
static void
dissect_spnego(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree)
{
proto_item *item;
proto_tree *subtree;
int offset = 0;
conversation_t *conversation;
/*
* We need this later, so lets get it now ...
* It has to be per-frame as there can be more than one GSS-API
* negotiation in a conversation.
*/
next_level_value = p_get_proto_data(pinfo->fd, proto_spnego);
if (!next_level_value && !pinfo->fd->flags.visited) {
/*
* No handle attached to this frame, but it's the first
* pass, so it'd be attached to the conversation.
* If we have a conversation, try to get the handle,
* and if we get one, attach it to the frame.
*/
conversation = find_conversation(pinfo->fd->num, &pinfo->src, &pinfo->dst,
pinfo->ptype, pinfo->srcport,
pinfo->destport, 0);
if (conversation) {
next_level_value = conversation_get_proto_data(conversation,
proto_spnego);
if (next_level_value)
p_add_proto_data(pinfo->fd, proto_spnego, next_level_value);
}
}
item = proto_tree_add_item(parent_tree, hf_spnego, tvb, offset,
-1, FALSE);
subtree = proto_item_add_subtree(item, ett_spnego);
/*
* The TVB contains a [0] header and a sequence that consists of an
* object ID and a blob containing the data ...
* Actually, it contains, according to RFC2478:
* NegotiationToken ::= CHOICE {
* negTokenInit [0] NegTokenInit,
* negTokenTarg [1] NegTokenTarg }
* NegTokenInit ::= SEQUENCE {
* mechTypes [0] MechTypeList OPTIONAL,
* reqFlags [1] ContextFlags OPTIONAL,
* mechToken [2] OCTET STRING OPTIONAL,
* mechListMIC [3] OCTET STRING OPTIONAL }
* NegTokenTarg ::= SEQUENCE {
* negResult [0] ENUMERATED {
* accept_completed (0),
* accept_incomplete (1),
* reject (2) } OPTIONAL,
* supportedMech [1] MechType OPTIONAL,
* responseToken [2] OCTET STRING OPTIONAL,
* mechListMIC [3] OCTET STRING OPTIONAL }
*
* Windows typically includes mechTypes and mechListMic ('NONE'
* in the case of NTLMSSP only).
* It seems to duplicate the responseToken into the mechListMic field
* as well. Naughty, naughty.
*
*/
offset = dissect_spnego_NegotiationToken(FALSE, tvb, offset, pinfo, subtree, -1);
}
/*--- proto_register_spnego -------------------------------------------*/
void proto_register_spnego(void) {
/* List of fields */
static hf_register_info hf[] = {
{ &hf_spnego,
{ "SPNEGO", "spnego", FT_NONE, BASE_NONE, NULL, 0x0,
"SPNEGO", HFILL }},
{ &hf_spnego_wraptoken,
{ "wrapToken", "spnego.wraptoken",
FT_NONE, BASE_NONE, NULL, 0x0, "SPNEGO wrapToken",
HFILL}},
{ &hf_spnego_krb5,
{ "krb5_blob", "spnego.krb5.blob", FT_BYTES,
BASE_NONE, NULL, 0, "krb5_blob", HFILL }},
{ &hf_spnego_krb5_oid,
{ "KRB5 OID", "spnego.krb5_oid", FT_STRING,
BASE_NONE, NULL, 0, "KRB5 OID", HFILL }},
{ &hf_spnego_krb5_tok_id,
{ "krb5_tok_id", "spnego.krb5.tok_id", FT_UINT16, BASE_HEX,
VALS(spnego_krb5_tok_id_vals), 0, "KRB5 Token Id", HFILL}},
{ &hf_spnego_krb5_sgn_alg,
{ "krb5_sgn_alg", "spnego.krb5.sgn_alg", FT_UINT16, BASE_HEX,
VALS(spnego_krb5_sgn_alg_vals), 0, "KRB5 Signing Algorithm", HFILL}},
{ &hf_spnego_krb5_seal_alg,
{ "krb5_seal_alg", "spnego.krb5.seal_alg", FT_UINT16, BASE_HEX,
VALS(spnego_krb5_seal_alg_vals), 0, "KRB5 Sealing Algorithm", HFILL}},
{ &hf_spnego_krb5_snd_seq,
{ "krb5_snd_seq", "spnego.krb5.snd_seq", FT_BYTES, BASE_NONE,
NULL, 0, "KRB5 Encrypted Sequence Number", HFILL}},
{ &hf_spnego_krb5_sgn_cksum,
{ "krb5_sgn_cksum", "spnego.krb5.sgn_cksum", FT_BYTES, BASE_NONE,
NULL, 0, "KRB5 Data Checksum", HFILL}},
{ &hf_spnego_krb5_confounder,
{ "krb5_confounder", "spnego.krb5.confounder", FT_BYTES, BASE_NONE,
NULL, 0, "KRB5 Confounder", HFILL}},
#include "packet-spnego-hfarr.c"
};
/* List of subtrees */
static gint *ett[] = {
&ett_spnego,
&ett_spnego_wraptoken,
&ett_spnego_krb5,
#include "packet-spnego-ettarr.c"
};
/* Register protocol */
proto_spnego = proto_register_protocol(PNAME, PSNAME, PFNAME);
proto_spnego_krb5 = proto_register_protocol("SPNEGO-KRB5",
"SPNEGO-KRB5",
"spnego-krb5");
/* Register fields and subtrees */
proto_register_field_array(proto_spnego, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
/*--- proto_reg_handoff_spnego ---------------------------------------*/
void proto_reg_handoff_spnego(void) {
dissector_handle_t spnego_handle, spnego_wrap_handle;
dissector_handle_t spnego_krb5_handle, spnego_krb5_wrap_handle;
/* Register protocol with GSS-API module */
spnego_handle = create_dissector_handle(dissect_spnego, proto_spnego);
spnego_wrap_handle = new_create_dissector_handle(dissect_spnego_wrap,
proto_spnego);
gssapi_init_oid("1.3.6.1.5.5.2", proto_spnego, ett_spnego,
spnego_handle, spnego_wrap_handle,
"SPNEGO - Simple Protected Negotiation");
/* Register both the one MS created and the real one */
/*
* Thanks to Jean-Baptiste Marchand and Richard B Ward, the
* mystery of the MS KRB5 OID is cleared up. It was due to a library
* that did not handle OID components greater than 16 bits, and was
* fixed in Win2K SP2 as well as WinXP.
* See the archive of <ietf-krb-wg@anl.gov> for the thread topic
* SPNEGO implementation issues. 3-Dec-2002.
*/
spnego_krb5_handle = create_dissector_handle(dissect_spnego_krb5,
proto_spnego_krb5);
spnego_krb5_wrap_handle = new_create_dissector_handle(dissect_spnego_krb5_wrap,
proto_spnego_krb5);
gssapi_init_oid("1.2.840.48018.1.2.2", proto_spnego_krb5, ett_spnego_krb5,
spnego_krb5_handle, spnego_krb5_wrap_handle,
"MS KRB5 - Microsoft Kerberos 5");
gssapi_init_oid("1.2.840.113554.1.2.2", proto_spnego_krb5, ett_spnego_krb5,
spnego_krb5_handle, spnego_krb5_wrap_handle,
"KRB5 - Kerberos 5");
gssapi_init_oid("1.2.840.113554.1.2.2.3", proto_spnego_krb5, ett_spnego_krb5,
spnego_krb5_handle, spnego_krb5_wrap_handle,
"KRB5 - Kerberos 5 - User to User");
/*
* Find the data handle for some calls
*/
data_handle = find_dissector("data");
}
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