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wireshark/packet-gssapi.c

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/* packet-gssapi.c
* Dissector for GSS-API tokens as described in rfc2078, section 3.1
* Copyright 2002, Tim Potter <tpot@samba.org>
* Copyright 2002, Richard Sharpe <rsharpe@samba.org> Added a few
* bits and pieces ...
*
* $Id: packet-gssapi.c,v 1.29 2004/01/19 20:10:36 jmayer Exp $
*
* 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.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#include <string.h>
#include <glib.h>
#include <epan/packet.h>
#include "asn1.h"
#include "format-oid.h"
#include "packet-dcerpc.h"
#include "packet-gssapi.h"
#include "packet-frame.h"
#include "epan/conversation.h"
static int proto_gssapi = -1;
static int hf_gssapi = -1;
static gint ett_gssapi = -1;
/*
* Subdissectors
*/
static GHashTable *gssapi_oids;
static gint gssapi_oid_equal(gconstpointer k1, gconstpointer k2)
{
const char *key1 = (const char *)k1;
const char *key2 = (const char *)k2;
return strcmp(key1, key2) == 0;
}
static guint
gssapi_oid_hash(gconstpointer k)
{
const char *key = (const char *)k;
guint hash = 0, i;
for (i = 0; i < strlen(key); i++)
hash += key[i];
return hash;
}
void
gssapi_init_oid(char *oid, int proto, int ett, dissector_handle_t handle,
dissector_handle_t wrap_handle, gchar *comment)
{
char *key = g_strdup(oid);
gssapi_oid_value *value = g_malloc(sizeof(*value));
value->proto = find_protocol_by_id(proto);
value->ett = ett;
value->handle = handle;
value->wrap_handle = wrap_handle;
value->comment = comment;
g_hash_table_insert(gssapi_oids, key, value);
}
/*
* This takes an OID in binary form, not an OID as a text string, as
* an argument.
*/
gssapi_oid_value *
gssapi_lookup_oid(subid_t *oid, guint oid_len)
{
gchar *oid_key;
gchar *p;
unsigned int i;
int len;
gssapi_oid_value *value;
/*
* Convert the OID to a string, as text strings are used as
* keys in the OID hash table.
*/
oid_key = g_malloc(oid_len * 22 + 1);
p = oid_key;
len = sprintf(p, "%lu", (unsigned long)oid[0]);
p += len;
for (i = 1; i < oid_len;i++) {
len = sprintf(p, ".%lu", (unsigned long)oid[i]);
p += len;
}
value = g_hash_table_lookup(gssapi_oids, oid_key);
g_free(oid_key);
return value;
}
/* Display an ASN1 parse error. Taken from packet-snmp.c */
static dissector_handle_t data_handle;
static void
dissect_parse_error(tvbuff_t *tvb, int offset, packet_info *pinfo,
proto_tree *tree, const char *field_name, int ret)
{
char *errstr;
errstr = asn1_err_to_str(ret);
if (tree != NULL) {
proto_tree_add_text(tree, tvb, offset, 0,
"ERROR: Couldn't parse %s: %s", field_name, errstr);
call_dissector(data_handle,
tvb_new_subset(tvb, offset, -1, -1), pinfo, tree);
}
}
static int
dissect_gssapi_work(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
gboolean is_verifier)
{
proto_item *item;
proto_tree *subtree;
ASN1_SCK hnd;
int ret, offset = 0;
volatile int return_offset = 0;
gboolean def;
guint len1, oid_len, cls, con, tag, nbytes;
subid_t *oid;
gchar *oid_string;
gssapi_oid_value *value;
volatile dissector_handle_t handle;
conversation_t *volatile conversation;
tvbuff_t *oid_tvb;
int len;
/*
* We need this later, so lets get it now ...
*/
conversation = find_conversation(&pinfo->src, &pinfo->dst,
pinfo->ptype, pinfo->srcport,
pinfo->destport, 0);
item = proto_tree_add_item(
tree, hf_gssapi, tvb, offset, -1, FALSE);
subtree = proto_item_add_subtree(item, ett_gssapi);
/*
* Catch the ReportedBoundsError exception; the stuff we've been
* handed doesn't necessarily run to the end of the packet, it's
* an item inside a packet, so if it happens to be malformed (or
* we, or a dissector we call, has a bug), so that an exception
* is thrown, we want to report the error, but return and let
* our caller dissect the rest of the packet.
*
* If it gets a BoundsError, we can stop, as there's nothing more
* in the packet after our blob to see, so we just re-throw the
* exception.
*/
TRY {
/* Read header */
asn1_open(&hnd, tvb, offset);
ret = asn1_header_decode(&hnd, &cls, &con, &tag, &def, &len1);
if (ret != ASN1_ERR_NOERROR) {
dissect_parse_error(tvb, offset, pinfo, subtree,
"GSS-API header", ret);
return_offset = tvb_length(tvb);
goto done;
}
if (!(cls == ASN1_APL && con == ASN1_CON && tag == 0)) {
/*
* If we do not recognise an Application class,
* then we are probably dealing with an inner context
* token or a wrap token, and we should retrieve the
* gssapi_oid_value pointer from the per-frame data or,
* if there is no per-frame data (as would be the case
* the first time we dissect this frame), from the
* conversation that exists or that we created from
* pinfo (and then make it per-frame data).
* We need to make it per-frame data as there can be
* more than one GSS-API negotiation in a conversation.
*
* Note! We "cheat". Since we only need the pointer,
* we store that as the data. (That's not really
* "cheating" - the per-frame data and per-conversation
* data code doesn't care what you supply as a data
* pointer; it just treats it as an opaque pointer, it
* doesn't dereference it or free what it points to.)
*/
value = p_get_proto_data(pinfo->fd, proto_gssapi);
if (!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. */
if (conversation)
{
value = conversation_get_proto_data(conversation,
proto_gssapi);
if (value)
p_add_proto_data(pinfo->fd, proto_gssapi, value);
}
}
if (!value)
{
proto_tree_add_text(subtree, tvb, offset, 0,
"Unknown header (cls=%d, con=%d, tag=%d)",
cls, con, tag);
return_offset = tvb_length(tvb);
goto done;
}
else
{
tvbuff_t *oid_tvb;
/* Naughty ... no way to reset the offset */
/* Account for the fact we have consumed part of the */
/* ASN.1 and we want to get it back */
hnd.offset = offset;
oid_tvb = tvb_new_subset(tvb, offset, -1, -1);
if (is_verifier)
handle = value->wrap_handle;
else
handle = value->handle;
len = call_dissector(handle, oid_tvb, pinfo, subtree);
if (len == 0)
return_offset = tvb_length(tvb);
else
return_offset = offset + len;
goto done; /* We are finished here */
}
}
offset = hnd.offset;
/* Read oid */
ret = asn1_oid_decode(&hnd, &oid, &oid_len, &nbytes);
if (ret != ASN1_ERR_NOERROR) {
dissect_parse_error(tvb, offset, pinfo, subtree,
"GSS-API token", ret);
return_offset = tvb_length(tvb);
goto done;
}
oid_string = format_oid(oid, oid_len);
/*
* Hand off to subdissector.
*/
if (((value = gssapi_lookup_oid(oid, oid_len)) == NULL) ||
!proto_is_protocol_enabled(value->proto)) {
proto_tree_add_text(subtree, tvb, offset, nbytes,
"OID: %s",
oid_string);
offset += nbytes;
g_free(oid_string);
/* No dissector for this oid */
proto_tree_add_text(subtree, tvb, offset, -1,
"Token object");
return_offset = tvb_length(tvb);
goto done;
}
if (value)
proto_tree_add_text(subtree, tvb, offset, nbytes,
"OID: %s (%s)",
oid_string, value->comment);
else
proto_tree_add_text(subtree, tvb, offset, nbytes, "OID: %s",
oid_string);
offset += nbytes;
g_free(oid_string);
/*
* This is not needed, as the sub-dissector adds a tree
sub_item = proto_tree_add_item(subtree, value->proto, tvb,
offset, -1, FALSE);
oid_subtree = proto_item_add_subtree(sub_item, value->ett);
*/
/*
* Here we should create a conversation if needed and
* save a pointer to the data for that OID for the
* GSSAPI protocol.
*/
if (!conversation) { /* Create one */
conversation = conversation_new(&pinfo->src,
&pinfo->dst,
pinfo->ptype,
pinfo->srcport,
pinfo->destport, 0);
}
/*
* Now add the proto data ...
* but only if it is not already there.
*/
if (!conversation_get_proto_data(conversation,
proto_gssapi)) {
conversation_add_proto_data(conversation,
proto_gssapi, value);
}
if (is_verifier) {
handle = value->wrap_handle;
if (handle != NULL) {
oid_tvb = tvb_new_subset(tvb, offset, -1, -1);
len = call_dissector(handle, oid_tvb, pinfo,
subtree);
if (len == 0)
return_offset = tvb_length(tvb);
else
return_offset = offset + len;
} else {
proto_tree_add_text(subtree, tvb, offset, -1,
"Authentication verifier");
return_offset = tvb_length(tvb);
}
} else {
handle = value->handle;
if (handle != NULL) {
oid_tvb = tvb_new_subset(tvb, offset, -1, -1);
len = call_dissector(handle, oid_tvb, pinfo,
subtree);
if (len == 0)
return_offset = tvb_length(tvb);
else
return_offset = offset + len;
} else {
proto_tree_add_text(subtree, tvb, offset, -1,
"Authentication credentials");
return_offset = tvb_length(tvb);
}
}
done:
asn1_close(&hnd, &offset);
} CATCH(BoundsError) {
RETHROW;
} CATCH(ReportedBoundsError) {
show_reported_bounds_error(tvb, pinfo, tree);
} ENDTRY;
proto_item_set_len(item, return_offset);
return return_offset;
}
static void
dissect_gssapi(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
dissect_gssapi_work(tvb, pinfo, tree, FALSE);
}
static int
dissect_gssapi_verf(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
return dissect_gssapi_work(tvb, pinfo, tree, TRUE);
}
void
proto_register_gssapi(void)
{
static hf_register_info hf[] = {
{ &hf_gssapi,
{ "GSS-API", "gss-api", FT_NONE, BASE_NONE, NULL, 0x0,
"GSS-API", HFILL }},
};
static gint *ett[] = {
&ett_gssapi,
};
proto_gssapi = proto_register_protocol(
"Generic Security Service Application Program Interface",
"GSS-API", "gss-api");
proto_register_field_array(proto_gssapi, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
register_dissector("gssapi", dissect_gssapi, proto_gssapi);
new_register_dissector("gssapi_verf", dissect_gssapi_verf, proto_gssapi);
gssapi_oids = g_hash_table_new(gssapi_oid_hash, gssapi_oid_equal);
}
static int wrap_dissect_gssapi(tvbuff_t *tvb, int offset,
packet_info *pinfo,
proto_tree *tree, guint8 *drep _U_)
{
tvbuff_t *auth_tvb;
auth_tvb = tvb_new_subset(
tvb, offset, tvb_length_remaining(tvb, offset),
tvb_length_remaining(tvb, offset));
dissect_gssapi(auth_tvb, pinfo, tree);
return tvb_length_remaining(tvb, offset);
}
static int wrap_dissect_gssapi_verf(tvbuff_t *tvb, int offset,
packet_info *pinfo,
proto_tree *tree, guint8 *drep _U_)
{
tvbuff_t *auth_tvb;
auth_tvb = tvb_new_subset(
tvb, offset, tvb_length_remaining(tvb, offset),
tvb_length_remaining(tvb, offset));
return dissect_gssapi_verf(auth_tvb, pinfo, tree);
}
static dcerpc_auth_subdissector_fns gssapi_auth_fns = {
wrap_dissect_gssapi, /* Bind */
wrap_dissect_gssapi, /* Bind ACK */
wrap_dissect_gssapi, /* AUTH3 */
wrap_dissect_gssapi_verf, /* Request verifier */
wrap_dissect_gssapi_verf, /* Response verifier */
NULL, /* Request data */
NULL /* Response data */
};
void
proto_reg_handoff_gssapi(void)
{
data_handle = find_dissector("data");
register_dcerpc_auth_subdissector(DCE_C_AUTHN_LEVEL_PKT_PRIVACY,
DCE_C_RPC_AUTHN_PROTOCOL_SPNEGO,
&gssapi_auth_fns);
}
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