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clispnego.c

/* 
   Unix SMB/Netbios implementation.
   Version 3.0
   simple kerberos5/SPNEGO routines
   Copyright (C) Andrew Tridgell 2001
   
   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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

/*
  generate a negTokenInit packet given a GUID, a list of supported
  OIDs (the mechanisms) and a principal name string 
*/
DATA_BLOB spnego_gen_negTokenInit(uint8 guid[16], 
                          const char *OIDs[], 
                          const char *principal)
{
      int i;
      ASN1_DATA data;
      DATA_BLOB ret;

      memset(&data, 0, sizeof(data));

      asn1_write(&data, guid, 16);
      asn1_push_tag(&data,ASN1_APPLICATION(0));
      asn1_write_OID(&data,OID_SPNEGO);
      asn1_push_tag(&data,ASN1_CONTEXT(0));
      asn1_push_tag(&data,ASN1_SEQUENCE(0));

      asn1_push_tag(&data,ASN1_CONTEXT(0));
      asn1_push_tag(&data,ASN1_SEQUENCE(0));
      for (i=0; OIDs[i]; i++) {
            asn1_write_OID(&data,OIDs[i]);
      }
      asn1_pop_tag(&data);
      asn1_pop_tag(&data);

      asn1_push_tag(&data, ASN1_CONTEXT(3));
      asn1_push_tag(&data, ASN1_SEQUENCE(0));
      asn1_push_tag(&data, ASN1_CONTEXT(0));
      asn1_write_GeneralString(&data,principal);
      asn1_pop_tag(&data);
      asn1_pop_tag(&data);
      asn1_pop_tag(&data);

      asn1_pop_tag(&data);
      asn1_pop_tag(&data);

      asn1_pop_tag(&data);

      if (data.has_error) {
            DEBUG(1,("Failed to build negTokenInit at offset %d\n", (int)data.ofs));
            asn1_free(&data);
      }

      ret = data_blob(data.data, data.length);
      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(DATA_BLOB blob,
                         uint8 guid[16], 
                         char *OIDs[ASN1_MAX_OIDS], 
                         char **principal)
{
      int i;
      BOOL ret;
      ASN1_DATA data;

      asn1_load(&data, blob);

      asn1_read(&data, guid, 16);
      asn1_start_tag(&data,ASN1_APPLICATION(0));
      asn1_check_OID(&data,OID_SPNEGO);
      asn1_start_tag(&data,ASN1_CONTEXT(0));
      asn1_start_tag(&data,ASN1_SEQUENCE(0));

      asn1_start_tag(&data,ASN1_CONTEXT(0));
      asn1_start_tag(&data,ASN1_SEQUENCE(0));
      for (i=0; asn1_tag_remaining(&data) > 0 && i < ASN1_MAX_OIDS; i++) {
            char *oid = NULL;
            asn1_read_OID(&data,&oid);
            OIDs[i] = oid;
      }
      OIDs[i] = NULL;
      asn1_end_tag(&data);
      asn1_end_tag(&data);

      asn1_start_tag(&data, ASN1_CONTEXT(3));
      asn1_start_tag(&data, ASN1_SEQUENCE(0));
      asn1_start_tag(&data, ASN1_CONTEXT(0));
      asn1_read_GeneralString(&data,principal);
      asn1_end_tag(&data);
      asn1_end_tag(&data);
      asn1_end_tag(&data);

      asn1_end_tag(&data);
      asn1_end_tag(&data);

      asn1_end_tag(&data);

      ret = !data.has_error;
      asn1_free(&data);
      return ret;
}


/*
  generate a negTokenTarg packet given a list of OIDs and a security blob
*/
DATA_BLOB gen_negTokenTarg(const char *OIDs[], DATA_BLOB blob)
{
      int i;
      ASN1_DATA data;
      DATA_BLOB ret;

      memset(&data, 0, sizeof(data));

      asn1_push_tag(&data, ASN1_APPLICATION(0));
      asn1_write_OID(&data,OID_SPNEGO);
      asn1_push_tag(&data, ASN1_CONTEXT(0));
      asn1_push_tag(&data, ASN1_SEQUENCE(0));

      asn1_push_tag(&data, ASN1_CONTEXT(0));
      asn1_push_tag(&data, ASN1_SEQUENCE(0));
      for (i=0; OIDs[i]; i++) {
            asn1_write_OID(&data,OIDs[i]);
      }
      asn1_pop_tag(&data);
      asn1_pop_tag(&data);

      asn1_push_tag(&data, ASN1_CONTEXT(2));
      asn1_write_OctetString(&data,blob.data,blob.length);
      asn1_pop_tag(&data);

      asn1_pop_tag(&data);
      asn1_pop_tag(&data);

      asn1_pop_tag(&data);

      if (data.has_error) {
            DEBUG(1,("Failed to build negTokenTarg at offset %d\n", (int)data.ofs));
            asn1_free(&data);
      }

      ret = data_blob(data.data, data.length);
      asn1_free(&data);

      return ret;
}


/*
  parse a negTokenTarg packet giving a list of OIDs and a security blob
*/
BOOL parse_negTokenTarg(DATA_BLOB blob, char *OIDs[ASN1_MAX_OIDS], DATA_BLOB *secblob)
{
      int i;
      ASN1_DATA data;

      asn1_load(&data, blob);
      asn1_start_tag(&data, ASN1_APPLICATION(0));
      asn1_check_OID(&data,OID_SPNEGO);
      asn1_start_tag(&data, ASN1_CONTEXT(0));
      asn1_start_tag(&data, ASN1_SEQUENCE(0));

      asn1_start_tag(&data, ASN1_CONTEXT(0));
      asn1_start_tag(&data, ASN1_SEQUENCE(0));
      for (i=0; asn1_tag_remaining(&data) > 0 && i < ASN1_MAX_OIDS; i++) {
            char *oid = NULL;
            asn1_read_OID(&data,&oid);
            OIDs[i] = oid;
      }
      OIDs[i] = NULL;
      asn1_end_tag(&data);
      asn1_end_tag(&data);

      asn1_start_tag(&data, ASN1_CONTEXT(2));
      asn1_read_OctetString(&data,secblob);
      asn1_end_tag(&data);

      asn1_end_tag(&data);
      asn1_end_tag(&data);

      asn1_end_tag(&data);

      if (data.has_error) {
            DEBUG(1,("Failed to parse negTokenTarg at offset %d\n", (int)data.ofs));
            asn1_free(&data);
            return False;
      }

      asn1_free(&data);
      return True;
}

/*
  generate a krb5 GSS-API wrapper packet given a ticket
*/
static DATA_BLOB spnego_gen_krb5_wrap(DATA_BLOB ticket)
{
      ASN1_DATA data;
      DATA_BLOB ret;

      memset(&data, 0, sizeof(data));

      asn1_push_tag(&data, ASN1_APPLICATION(0));
      asn1_write_OID(&data, OID_KERBEROS5);
      asn1_write_BOOLEAN(&data, 0);
      asn1_write(&data, ticket.data, ticket.length);
      asn1_pop_tag(&data);

      if (data.has_error) {
            DEBUG(1,("Failed to build krb5 wrapper at offset %d\n", (int)data.ofs));
            asn1_free(&data);
      }

      ret = data_blob(data.data, data.length);
      asn1_free(&data);

      return ret;
}

/*
  parse a krb5 GSS-API wrapper packet giving a ticket
*/
BOOL spnego_parse_krb5_wrap(DATA_BLOB blob, DATA_BLOB *ticket)
{
      BOOL ret;
      ASN1_DATA data;
      int ata_remaining;

      asn1_load(&data, blob);
      asn1_start_tag(&data, ASN1_APPLICATION(0));
      asn1_check_OID(&data, OID_KERBEROS5);
      asn1_check_BOOLEAN(&data, 0);

      data_remaining = asn1_tag_remaining(&data);

      if (data_remaining < 1) {
            data.has_error = True;
      } else {
            *ticket = data_blob(data.data, data_remaining);
            asn1_read(&data, ticket->data, ticket->length);
      }

      asn1_end_tag(&data);

      ret = !data.has_error;

      asn1_free(&data);

      return ret;
}


/* 
   generate a SPNEGO negTokenTarg packet, ready for a EXTENDED_SECURITY
   kerberos session setup 
*/
DATA_BLOB spnego_gen_negTokenTarg(struct cli_state *cli, char *principal)
{
      DATA_BLOB tkt, tkt_wrapped, targ;
      const char *krb_mechs[] = {OID_KERBEROS5_OLD, OID_NTLMSSP, NULL};

      /* get a kerberos ticket for the service */
      tkt = krb5_get_ticket(principal);

      /* wrap that up in a nice GSS-API wrapping */
      tkt_wrapped = spnego_gen_krb5_wrap(tkt);

      /* and wrap that in a shiny SPNEGO wrapper */
      targ = gen_negTokenTarg(krb_mechs, tkt_wrapped);

      data_blob_free(&tkt_wrapped);
      data_blob_free(&tkt);

      return targ;
}


/*
  parse a spnego NTLMSSP challenge packet giving two security blobs
*/
BOOL spnego_parse_challenge(DATA_BLOB blob,
                      DATA_BLOB *chal1, DATA_BLOB *chal2)
{
      BOOL ret;
      ASN1_DATA data;

      ZERO_STRUCTP(chal1);
      ZERO_STRUCTP(chal2);

      asn1_load(&data, blob);
      asn1_start_tag(&data,ASN1_CONTEXT(1));
      asn1_start_tag(&data,ASN1_SEQUENCE(0));

      asn1_start_tag(&data,ASN1_CONTEXT(0));
      asn1_check_enumerated(&data,1);
      asn1_end_tag(&data);

      asn1_start_tag(&data,ASN1_CONTEXT(1));
      asn1_check_OID(&data, OID_NTLMSSP);
      asn1_end_tag(&data);

      asn1_start_tag(&data,ASN1_CONTEXT(2));
      asn1_read_OctetString(&data, chal1);
      asn1_end_tag(&data);

      /* the second challenge is optional (XP doesn't send it) */
      if (asn1_tag_remaining(&data)) {
            asn1_start_tag(&data,ASN1_CONTEXT(3));
            asn1_read_OctetString(&data, chal2);
            asn1_end_tag(&data);
      }

      asn1_end_tag(&data);
      asn1_end_tag(&data);

      ret = !data.has_error;
      asn1_free(&data);
      return ret;
}


/*
  generate a spnego NTLMSSP challenge packet given two security blobs
  The second challenge is optional
*/
BOOL spnego_gen_challenge(DATA_BLOB *blob,
                    DATA_BLOB *chal1, DATA_BLOB *chal2)
{
      ASN1_DATA data;

      ZERO_STRUCT(data);

      asn1_push_tag(&data,ASN1_CONTEXT(1));
      asn1_push_tag(&data,ASN1_SEQUENCE(0));

      asn1_push_tag(&data,ASN1_CONTEXT(0));
      asn1_write_enumerated(&data,1);
      asn1_pop_tag(&data);

      asn1_push_tag(&data,ASN1_CONTEXT(1));
      asn1_write_OID(&data, OID_NTLMSSP);
      asn1_pop_tag(&data);

      asn1_push_tag(&data,ASN1_CONTEXT(2));
      asn1_write_OctetString(&data, chal1->data, chal1->length);
      asn1_pop_tag(&data);

      /* the second challenge is optional (XP doesn't send it) */
      if (chal2) {
            asn1_push_tag(&data,ASN1_CONTEXT(3));
            asn1_write_OctetString(&data, chal2->data, chal2->length);
            asn1_pop_tag(&data);
      }

      asn1_pop_tag(&data);
      asn1_pop_tag(&data);

      if (data.has_error) {
            return False;
      }

      *blob = data_blob(data.data, data.length);
      asn1_free(&data);
      return True;
}

/*
 generate a SPNEGO NTLMSSP auth packet. This will contain the encrypted passwords
*/
DATA_BLOB spnego_gen_auth(DATA_BLOB blob)
{
      ASN1_DATA data;
      DATA_BLOB ret;

      memset(&data, 0, sizeof(data));

      asn1_push_tag(&data, ASN1_CONTEXT(1));
      asn1_push_tag(&data, ASN1_SEQUENCE(0));
      asn1_push_tag(&data, ASN1_CONTEXT(2));
      asn1_write_OctetString(&data,blob.data,blob.length);  
      asn1_pop_tag(&data);
      asn1_pop_tag(&data);
      asn1_pop_tag(&data);

      ret = data_blob(data.data, data.length);

      asn1_free(&data);

      return ret;
}

/*
 parse a SPNEGO NTLMSSP auth packet. This contains the encrypted passwords
*/
BOOL spnego_parse_auth(DATA_BLOB blob, DATA_BLOB *auth)
{
      ASN1_DATA data;

      asn1_load(&data, blob);
      asn1_start_tag(&data, ASN1_CONTEXT(1));
      asn1_start_tag(&data, ASN1_SEQUENCE(0));
      asn1_start_tag(&data, ASN1_CONTEXT(2));
      asn1_read_OctetString(&data,auth);
      asn1_end_tag(&data);
      asn1_end_tag(&data);
      asn1_end_tag(&data);

      if (data.has_error) {
            DEBUG(3,("spnego_parse_auth failed at %d\n", (int)data.ofs));
            asn1_free(&data);
            return False;
      }

      asn1_free(&data);
      return True;
}


/*
  this is a tiny msrpc packet generator. I am only using this to
  avoid tying this code to a particular varient of our rpc code. This
  generator is not general enough for all our rpc needs, its just
  enough for the spnego/ntlmssp code

  format specifiers are:

  U = unicode string (input is unix string)
  B = data blob (pointer + length)
  b = data blob in header (pointer + length)
  d = word (4 bytes)
  C = constant ascii string
 */
BOOL msrpc_gen(DATA_BLOB *blob,
             const char *format, ...)
{
      int i, n;
      va_list ap;
      char *s;
      uint8 *b;
      int head_size=0, data_size=0;
      int head_ofs, data_ofs;

      /* first scan the format to work out the header and body size */
      va_start(ap, format);
      for (i=0; format[i]; i++) {
            switch (format[i]) {
            case 'U':
                  s = va_arg(ap, char *);
                  head_size += 8;
                  data_size += str_charnum(s) * 2;
                  break;
            case 'B':
                  b = va_arg(ap, uint8 *);
                  head_size += 8;
                  data_size += va_arg(ap, int);
                  break;
            case 'b':
                  b = va_arg(ap, uint8 *);
                  head_size += va_arg(ap, int);
                  break;
            case 'd':
                  n = va_arg(ap, int);
                  head_size += 4;
                  break;
            case 'C':
                  s = va_arg(ap, char *);
                  head_size += str_charnum(s) + 1;
                  break;
            }
      }
      va_end(ap);

      /* allocate the space, then scan the format again to fill in the values */
      blob->data = malloc(head_size + data_size);
      blob->length = head_size + data_size;
      if (!blob->data) return False;

      head_ofs = 0;
      data_ofs = head_size;

      va_start(ap, format);
      for (i=0; format[i]; i++) {
            switch (format[i]) {
            case 'U':
                  s = va_arg(ap, char *);
                  n = str_charnum(s);
                  SSVAL(blob->data, head_ofs, n*2); head_ofs += 2;
                  SSVAL(blob->data, head_ofs, n*2); head_ofs += 2;
                  SIVAL(blob->data, head_ofs, data_ofs); head_ofs += 4;
                  push_string(NULL, blob->data+data_ofs, s, n*2, STR_UNICODE|STR_NOALIGN);
                  data_ofs += n*2;
                  break;
            case 'B':
                  b = va_arg(ap, uint8 *);
                  n = va_arg(ap, int);
                  SSVAL(blob->data, head_ofs, n); head_ofs += 2;
                  SSVAL(blob->data, head_ofs, n); head_ofs += 2;
                  SIVAL(blob->data, head_ofs, data_ofs); head_ofs += 4;
                  memcpy(blob->data+data_ofs, b, n);
                  data_ofs += n;
                  break;
            case 'd':
                  n = va_arg(ap, int);
                  SIVAL(blob->data, head_ofs, n); head_ofs += 4;
                  break;
            case 'b':
                  b = va_arg(ap, uint8 *);
                  n = va_arg(ap, int);
                  memcpy(blob->data + head_ofs, b, n);
                  head_ofs += n;
                  break;
            case 'C':
                  s = va_arg(ap, char *);
                  head_ofs += push_string(NULL, blob->data+head_ofs, s, -1, 
                                    STR_ASCII|STR_TERMINATE);
                  break;
            }
      }
      va_end(ap);

      return True;
}


/*
  this is a tiny msrpc packet parser. This the the partner of msrpc_gen

  format specifiers are:

  U = unicode string (input is unix string)
  B = data blob
  b = data blob in header
  d = word (4 bytes)
  C = constant ascii string
 */
BOOL msrpc_parse(DATA_BLOB *blob,
             const char *format, ...)
{
      int i;
      va_list ap;
      char **ps, *s;
      DATA_BLOB *b;
      int head_ofs = 0;
      uint16 len1, len2;
      uint32 ptr;
      uint32 *v;
      pstring p;

      va_start(ap, format);
      for (i=0; format[i]; i++) {
            switch (format[i]) {
            case 'U':
                  len1 = SVAL(blob->data, head_ofs); head_ofs += 2;
                  len2 = SVAL(blob->data, head_ofs); head_ofs += 2;
                  ptr =  IVAL(blob->data, head_ofs); head_ofs += 4;
                  /* make sure its in the right format - be strict */
                  if (len1 != len2 || (len1&1) || ptr + len1 > blob->length) {
                        return False;
                  }
                  ps = va_arg(ap, char **);
                  pull_string(NULL, p, blob->data + ptr, -1, len1, 
                            STR_UNICODE|STR_NOALIGN);
                  (*ps) = strdup(p);
                  break;
            case 'B':
                  len1 = SVAL(blob->data, head_ofs); head_ofs += 2;
                  len2 = SVAL(blob->data, head_ofs); head_ofs += 2;
                  ptr =  IVAL(blob->data, head_ofs); head_ofs += 4;
                  /* make sure its in the right format - be strict */
                  if (len1 != len2 || ptr + len1 > blob->length) {
                        return False;
                  }
                  b = (DATA_BLOB *)va_arg(ap, void *);
                  *b = data_blob(blob->data + ptr, len1);
                  break;
            case 'b':
                  b = (DATA_BLOB *)va_arg(ap, void *);
                  len1 = va_arg(ap, unsigned);
                  *b = data_blob(blob->data + head_ofs, len1);
                  head_ofs += len1;
                  break;
            case 'd':
                  v = va_arg(ap, uint32 *);
                  *v = IVAL(blob->data, head_ofs); head_ofs += 4;
                  break;
            case 'C':
                  s = va_arg(ap, char *);
                  head_ofs += pull_string(NULL, p, blob->data+head_ofs, -1, 
                                    blob->length - head_ofs, 
                                    STR_ASCII|STR_TERMINATE);
                  if (strcmp(s, p) != 0) {
                        return False;
                  }
                  break;
            }
      }
      va_end(ap);

      return True;
}

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