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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* The ASB.1/BER parsing code is derived from ip_nat_snmp_basic.c which was in
* turn derived from the gxsnmp package by Gregory McLean & Jochen Friedrich
*
* Copyright (c) 2000 RP Internet (www.rpi.net.au).
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/oid_registry.h>
#include "glob.h"
#include "asn1.h"
#include "connection.h"
#include "auth.h"
#include "ksmbd_spnego_negtokeninit.asn1.h"
#include "ksmbd_spnego_negtokentarg.asn1.h"
#define NTLMSSP_OID_LEN 10
static char NTLMSSP_OID_STR[NTLMSSP_OID_LEN] = { 0x2b, 0x06, 0x01, 0x04, 0x01,
0x82, 0x37, 0x02, 0x02, 0x0a };
int
ksmbd_decode_negTokenInit(unsigned char *security_blob, int length,
struct ksmbd_conn *conn)
{
return asn1_ber_decoder(&ksmbd_spnego_negtokeninit_decoder, conn,
security_blob, length);
}
int
ksmbd_decode_negTokenTarg(unsigned char *security_blob, int length,
struct ksmbd_conn *conn)
{
return asn1_ber_decoder(&ksmbd_spnego_negtokentarg_decoder, conn,
security_blob, length);
}
static int compute_asn_hdr_len_bytes(int len)
{
if (len > 0xFFFFFF)
return 4;
else if (len > 0xFFFF)
return 3;
else if (len > 0xFF)
return 2;
else if (len > 0x7F)
return 1;
else
return 0;
}
static void encode_asn_tag(char *buf, unsigned int *ofs, char tag, char seq,
int length)
{
int i;
int index = *ofs;
char hdr_len = compute_asn_hdr_len_bytes(length);
int len = length + 2 + hdr_len;
/* insert tag */
buf[index++] = tag;
if (!hdr_len) {
buf[index++] = len;
} else {
buf[index++] = 0x80 | hdr_len;
for (i = hdr_len - 1; i >= 0; i--)
buf[index++] = (len >> (i * 8)) & 0xFF;
}
/* insert seq */
len = len - (index - *ofs);
buf[index++] = seq;
if (!hdr_len) {
buf[index++] = len;
} else {
buf[index++] = 0x80 | hdr_len;
for (i = hdr_len - 1; i >= 0; i--)
buf[index++] = (len >> (i * 8)) & 0xFF;
}
*ofs += (index - *ofs);
}
int build_spnego_ntlmssp_neg_blob(unsigned char **pbuffer, u16 *buflen,
char *ntlm_blob, int ntlm_blob_len)
{
char *buf;
unsigned int ofs = 0;
int neg_result_len = 4 + compute_asn_hdr_len_bytes(1) * 2 + 1;
int oid_len = 4 + compute_asn_hdr_len_bytes(NTLMSSP_OID_LEN) * 2 +
NTLMSSP_OID_LEN;
int ntlmssp_len = 4 + compute_asn_hdr_len_bytes(ntlm_blob_len) * 2 +
ntlm_blob_len;
int total_len = 4 + compute_asn_hdr_len_bytes(neg_result_len +
oid_len + ntlmssp_len) * 2 +
neg_result_len + oid_len + ntlmssp_len;
buf = kmalloc(total_len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
/* insert main gss header */
encode_asn_tag(buf, &ofs, 0xa1, 0x30, neg_result_len + oid_len +
ntlmssp_len);
/* insert neg result */
encode_asn_tag(buf, &ofs, 0xa0, 0x0a, 1);
buf[ofs++] = 1;
/* insert oid */
encode_asn_tag(buf, &ofs, 0xa1, 0x06, NTLMSSP_OID_LEN);
memcpy(buf + ofs, NTLMSSP_OID_STR, NTLMSSP_OID_LEN);
ofs += NTLMSSP_OID_LEN;
/* insert response token - ntlmssp blob */
encode_asn_tag(buf, &ofs, 0xa2, 0x04, ntlm_blob_len);
memcpy(buf + ofs, ntlm_blob, ntlm_blob_len);
ofs += ntlm_blob_len;
*pbuffer = buf;
*buflen = total_len;
return 0;
}
int build_spnego_ntlmssp_auth_blob(unsigned char **pbuffer, u16 *buflen,
int neg_result)
{
char *buf;
unsigned int ofs = 0;
int neg_result_len = 4 + compute_asn_hdr_len_bytes(1) * 2 + 1;
int total_len = 4 + compute_asn_hdr_len_bytes(neg_result_len) * 2 +
neg_result_len;
buf = kmalloc(total_len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
/* insert main gss header */
encode_asn_tag(buf, &ofs, 0xa1, 0x30, neg_result_len);
/* insert neg result */
encode_asn_tag(buf, &ofs, 0xa0, 0x0a, 1);
if (neg_result)
buf[ofs++] = 2;
else
buf[ofs++] = 0;
*pbuffer = buf;
*buflen = total_len;
return 0;
}
int ksmbd_gssapi_this_mech(void *context, size_t hdrlen, unsigned char tag,
const void *value, size_t vlen)
{
enum OID oid;
oid = look_up_OID(value, vlen);
if (oid != OID_spnego) {
char buf[50];
sprint_oid(value, vlen, buf, sizeof(buf));
ksmbd_debug(AUTH, "Unexpected OID: %s\n", buf);
return -EBADMSG;
}
return 0;
}
int ksmbd_neg_token_init_mech_type(void *context, size_t hdrlen,
unsigned char tag, const void *value,
size_t vlen)
{
struct ksmbd_conn *conn = context;
enum OID oid;
int mech_type;
oid = look_up_OID(value, vlen);
if (oid == OID_ntlmssp) {
mech_type = KSMBD_AUTH_NTLMSSP;
} else if (oid == OID_mskrb5) {
mech_type = KSMBD_AUTH_MSKRB5;
} else if (oid == OID_krb5) {
mech_type = KSMBD_AUTH_KRB5;
} else if (oid == OID_krb5u2u) {
mech_type = KSMBD_AUTH_KRB5U2U;
} else {
char buf[50];
sprint_oid(value, vlen, buf, sizeof(buf));
ksmbd_debug(AUTH, "Unexpected OID: %s\n", buf);
return -EBADMSG;
}
conn->auth_mechs |= mech_type;
if (conn->preferred_auth_mech == 0)
conn->preferred_auth_mech = mech_type;
return 0;
}
static int ksmbd_neg_token_alloc(void *context, size_t hdrlen,
unsigned char tag, const void *value,
size_t vlen)
{
struct ksmbd_conn *conn = context;
conn->mechToken = kmalloc(vlen + 1, GFP_KERNEL);
if (!conn->mechToken)
return -ENOMEM;
memcpy(conn->mechToken, value, vlen);
conn->mechToken[vlen] = '\0';
return 0;
}
int ksmbd_neg_token_init_mech_token(void *context, size_t hdrlen,
unsigned char tag, const void *value,
size_t vlen)
{
return ksmbd_neg_token_alloc(context, hdrlen, tag, value, vlen);
}
int ksmbd_neg_token_targ_resp_token(void *context, size_t hdrlen,
unsigned char tag, const void *value,
size_t vlen)
{
return ksmbd_neg_token_alloc(context, hdrlen, tag, value, vlen);
}
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