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/*
Unix SMB/CIFS implementation.
simple kerberos5/SPNEGO routines
Copyright (C) Andrew Tridgell 2001
Copyright (C) Jim McDonough <jmcd@us.ibm.com> 2002
Copyright (C) Luke Howard 2003
Copyright (C) Jeremy Allison 2010
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "../libcli/auth/spnego.h"
#include "smb_krb5.h"
#include "../lib/util/asn1.h"
/*
parse a negTokenInit packet giving a GUID, a list of supported
OIDs (the mechanisms) and a principal name string
*/
bool spnego_parse_negTokenInit(TALLOC_CTX *ctx,
DATA_BLOB blob,
char *OIDs[ASN1_MAX_OIDS],
char **principal,
DATA_BLOB *secblob)
{
int i;
bool ret = false;
ASN1_DATA *data;
for (i = 0; i < ASN1_MAX_OIDS; i++) {
OIDs[i] = NULL;
}
if (principal) {
*principal = NULL;
}
if (secblob) {
*secblob = data_blob_null;
}
data = asn1_init(talloc_tos(), ASN1_MAX_TREE_DEPTH);
if (data == NULL) {
return false;
}
if (!asn1_load(data, blob)) goto err;
if (!asn1_start_tag(data,ASN1_APPLICATION(0))) goto err;
if (!asn1_check_OID(data,OID_SPNEGO)) goto err;
/* negTokenInit [0] NegTokenInit */
if (!asn1_start_tag(data,ASN1_CONTEXT(0))) goto err;
if (!asn1_start_tag(data,ASN1_SEQUENCE(0))) goto err;
/* mechTypes [0] MechTypeList OPTIONAL */
/* Not really optional, we depend on this to decide
* what mechanisms we have to work with. */
if (!asn1_start_tag(data,ASN1_CONTEXT(0))) goto err;
if (!asn1_start_tag(data,ASN1_SEQUENCE(0))) goto err;
for (i=0; asn1_tag_remaining(data) > 0 && i < ASN1_MAX_OIDS-1; i++) {
if (!asn1_read_OID(data,ctx, &OIDs[i])) {
goto err;
}
if (asn1_has_error(data)) {
goto err;
}
}
OIDs[i] = NULL;
if (!asn1_end_tag(data)) goto err;
if (!asn1_end_tag(data)) goto err;
/*
Win7 + Live Sign-in Assistant attaches a mechToken
ASN1_CONTEXT(2) to the negTokenInit packet
which breaks our negotiation if we just assume
the next tag is ASN1_CONTEXT(3).
*/
if (asn1_peek_tag(data, ASN1_CONTEXT(1))) {
uint8_t flags;
/* reqFlags [1] ContextFlags OPTIONAL */
if (!asn1_start_tag(data, ASN1_CONTEXT(1))) goto err;
if (!asn1_start_tag(data, ASN1_BIT_STRING)) goto err;
while (asn1_tag_remaining(data) > 0) {
if (!asn1_read_uint8(data, &flags)) goto err;
}
if (!asn1_end_tag(data)) goto err;
if (!asn1_end_tag(data)) goto err;
}
if (asn1_peek_tag(data, ASN1_CONTEXT(2))) {
DATA_BLOB sblob = data_blob_null;
/* mechToken [2] OCTET STRING OPTIONAL */
if (!asn1_start_tag(data, ASN1_CONTEXT(2))) goto err;
if (!asn1_read_OctetString(data, ctx, &sblob)) goto err;
if (!asn1_end_tag(data)) {
data_blob_free(&sblob);
goto err;
}
if (secblob) {
*secblob = sblob;
} else {
data_blob_free(&sblob);
}
}
if (asn1_peek_tag(data, ASN1_CONTEXT(3))) {
char *princ = NULL;
/* mechListMIC [3] OCTET STRING OPTIONAL */
if (!asn1_start_tag(data, ASN1_CONTEXT(3))) goto err;
if (!asn1_start_tag(data, ASN1_SEQUENCE(0))) goto err;
if (!asn1_start_tag(data, ASN1_CONTEXT(0))) goto err;
if (!asn1_read_GeneralString(data, ctx, &princ)) goto err;
if (!asn1_end_tag(data)) goto err;
if (!asn1_end_tag(data)) goto err;
if (!asn1_end_tag(data)) goto err;
if (principal) {
*principal = princ;
} else {
TALLOC_FREE(princ);
}
}
if (!asn1_end_tag(data)) goto err;
if (!asn1_end_tag(data)) goto err;
if (!asn1_end_tag(data)) goto err;
ret = !asn1_has_error(data);
err:
if (asn1_has_error(data)) {
int j;
if (principal) {
TALLOC_FREE(*principal);
}
if (secblob) {
data_blob_free(secblob);
}
for(j = 0; j < i && j < ASN1_MAX_OIDS-1; j++) {
TALLOC_FREE(OIDs[j]);
}
}
asn1_free(data);
return ret;
}
/*
generate a krb5 GSS-API wrapper packet given a ticket
*/
DATA_BLOB spnego_gen_krb5_wrap(TALLOC_CTX *ctx, const DATA_BLOB ticket, const uint8_t tok_id[2])
{
ASN1_DATA *data;
DATA_BLOB ret = data_blob_null;
data = asn1_init(talloc_tos(), ASN1_MAX_TREE_DEPTH);
if (data == NULL) {
return data_blob_null;
}
if (!asn1_push_tag(data, ASN1_APPLICATION(0))) goto err;
if (!asn1_write_OID(data, OID_KERBEROS5)) goto err;
if (!asn1_write(data, tok_id, 2)) goto err;
if (!asn1_write(data, ticket.data, ticket.length)) goto err;
if (!asn1_pop_tag(data)) goto err;
if (!asn1_extract_blob(data, ctx, &ret)) {
goto err;
}
asn1_free(data);
data = NULL;
err:
if (data != NULL) {
if (asn1_has_error(data)) {
DEBUG(1, ("Failed to build krb5 wrapper at offset %d\n",
(int)asn1_current_ofs(data)));
}
asn1_free(data);
}
return ret;
}
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