/*
parse a spnego NTLMSSP challenge packet giving two security blobs
*/
bool spnego_parse_challenge(TALLOC_CTX *ctx, const DATA_BLOB blob,
DATA_BLOB *chal1, DATA_BLOB *chal2)
{
bool ret = false;
ASN1_DATA *data;
ZERO_STRUCTP(chal1);
ZERO_STRUCTP(chal2);
data = asn1_init(talloc_tos());
if (data == NULL) {
return false;
}
if (!asn1_load(data, blob)) goto err;
if (!asn1_start_tag(data,ASN1_CONTEXT(1))) goto err;
if (!asn1_start_tag(data,ASN1_SEQUENCE(0))) goto err;
if (!asn1_start_tag(data,ASN1_CONTEXT(0))) goto err;
if (!asn1_check_enumerated(data,1)) goto err;
if (!asn1_end_tag(data)) goto err;
if (!asn1_start_tag(data,ASN1_CONTEXT(1))) goto err;
if (!asn1_check_OID(data, OID_NTLMSSP)) goto err;
if (!asn1_end_tag(data)) goto err;
if (!asn1_start_tag(data,ASN1_CONTEXT(2))) goto err;
if (!asn1_read_OctetString(data, ctx, chal1)) goto err;
if (!asn1_end_tag(data)) goto err;
/* the second challenge is optional (XP doesn't send it) */
if (asn1_tag_remaining(data)) {
if (!asn1_start_tag(data,ASN1_CONTEXT(3))) goto err;
if (!asn1_read_OctetString(data, ctx, chal2)) goto err;
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)) {
data_blob_free(chal1);
data_blob_free(chal2);
}
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());
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;
}
err:
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;
}
/*
magic check a GSS-API wrapper packet for an Kerberos OID
*/
static bool gensec_gssapi_check_oid(const DATA_BLOB *blob, const char *oid)
{
bool ret = false;
struct asn1_data *data = asn1_init(NULL);
if (!data) 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)) goto err;
ret = !asn1_has_error(data);
err:
asn1_free(data);
return ret;
}
/*
parse a SPNEGO auth packet. This contains the encrypted passwords
*/
bool spnego_parse_auth_response(TALLOC_CTX *ctx,
DATA_BLOB blob, NTSTATUS nt_status,
const char *mechOID,
DATA_BLOB *auth)
{
ASN1_DATA *data;
uint8_t negResult;
bool ret = false;
if (NT_STATUS_IS_OK(nt_status)) {
negResult = SPNEGO_ACCEPT_COMPLETED;
} else if (NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
negResult = SPNEGO_ACCEPT_INCOMPLETE;
} else {
negResult = SPNEGO_REJECT;
}
data = asn1_init(talloc_tos());
if (data == NULL) {
return false;
}
*auth = data_blob_null;
if (!asn1_load(data, blob)) goto err;
if (!asn1_start_tag(data, ASN1_CONTEXT(1))) goto err;
if (!asn1_start_tag(data, ASN1_SEQUENCE(0))) goto err;
if (!asn1_start_tag(data, ASN1_CONTEXT(0))) goto err;
if (!asn1_check_enumerated(data, negResult)) goto err;
if (!asn1_end_tag(data)) goto err;
if (asn1_tag_remaining(data)) {
if (!asn1_start_tag(data,ASN1_CONTEXT(1))) goto err;
if (!asn1_check_OID(data, mechOID)) goto err;
if (!asn1_end_tag(data)) goto err;
if (asn1_tag_remaining(data)) {
if (!asn1_start_tag(data,ASN1_CONTEXT(2))) goto err;
if (!asn1_read_OctetString(data, ctx, auth)) goto err;
if (!asn1_end_tag(data)) goto err;
}
} else if (negResult == SPNEGO_ACCEPT_INCOMPLETE) {
asn1_set_error(data);
goto err;
}
/* Binding against Win2K DC returns a duplicate of the responseToken in
* the optional mechListMIC field. This is a bug in Win2K. We ignore
* this field if it exists. Win2K8 may return a proper mechListMIC at
* which point we need to implement the integrity checking. */
if (asn1_tag_remaining(data)) {
DATA_BLOB mechList = data_blob_null;
if (!asn1_start_tag(data, ASN1_CONTEXT(3))) goto err;
if (!asn1_read_OctetString(data, ctx, &mechList)) goto err;
data_blob_free(&mechList);
if (!asn1_end_tag(data)) goto err;
DEBUG(5,("spnego_parse_auth_response received mechListMIC, "
"ignoring.\n"));
}
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)) {
DEBUG(3, ("spnego_parse_auth_response failed at %d\n",
(int)asn1_current_ofs(data)));
asn1_free(data);
data_blob_free(auth);
return false;
}
asn1_free(data);
return ret;
}
DATA_BLOB spnego_gen_negTokenInit(TALLOC_CTX *ctx,
const char *OIDs[],
DATA_BLOB *psecblob,
const char *principal)
{
int i;
ASN1_DATA *data;
DATA_BLOB ret = data_blob_null;
data = asn1_init(talloc_tos());
if (data == NULL) {
return data_blob_null;
}
if (!asn1_push_tag(data,ASN1_APPLICATION(0))) goto err;
if (!asn1_write_OID(data,OID_SPNEGO)) goto err;
if (!asn1_push_tag(data,ASN1_CONTEXT(0))) goto err;
if (!asn1_push_tag(data,ASN1_SEQUENCE(0))) goto err;
if (!asn1_push_tag(data,ASN1_CONTEXT(0))) goto err;
if (!asn1_push_tag(data,ASN1_SEQUENCE(0))) goto err;
for (i=0; OIDs[i]; i++) {
if (!asn1_write_OID(data,OIDs[i])) goto err;
}
if (!asn1_pop_tag(data)) goto err;
if (!asn1_pop_tag(data)) goto err;
if (psecblob && psecblob->length && psecblob->data) {
if (!asn1_push_tag(data, ASN1_CONTEXT(2))) goto err;
if (!asn1_write_OctetString(data,psecblob->data,
psecblob->length)) goto err;
if (!asn1_pop_tag(data)) goto err;
}
if (principal) {
if (!asn1_push_tag(data, ASN1_CONTEXT(3))) goto err;
if (!asn1_push_tag(data, ASN1_SEQUENCE(0))) goto err;
if (!asn1_push_tag(data, ASN1_CONTEXT(0))) goto err;
if (!asn1_write_GeneralString(data,principal)) goto err;
if (!asn1_pop_tag(data)) goto err;
if (!asn1_pop_tag(data)) goto err;
if (!asn1_pop_tag(data)) goto err;
}
if (!asn1_pop_tag(data)) goto err;
if (!asn1_pop_tag(data)) goto err;
if (!asn1_pop_tag(data)) goto err;
if (!asn1_extract_blob(data, ctx, &ret)) {
goto err;
}
err:
if (asn1_has_error(data)) {
DEBUG(1, ("Failed to build negTokenInit at offset %d\n",
(int)asn1_current_ofs(data)));
}
asn1_free(data);
return ret;
}
/*
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());
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;
}
