samba-mirror/source3/rpc_parse/parse_sec.c

/* 
 *  Unix SMB/CIFS implementation.
 *  RPC Pipe client / server routines
 *  Copyright (C) Andrew Tridgell              1992-1998,
 *  Copyright (C) Jeremy R. Allison            1995-1998
 *  Copyright (C) Luke Kenneth Casson Leighton 1996-1998,
 *  Copyright (C) Paul Ashton                  1997-1998.
 *  
 *  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"

/*******************************************************************
 Sets up a SEC_ACCESS structure.
********************************************************************/

void init_sec_access(SEC_ACCESS *t, uint32 mask)
{
	t->mask = mask;
}

/*******************************************************************
 Reads or writes a SEC_ACCESS structure.
********************************************************************/

BOOL sec_io_access(char *desc, SEC_ACCESS *t, prs_struct *ps, int depth)
{
	if (t == NULL)
		return False;

	prs_debug(ps, depth, desc, "sec_io_access");
	depth++;

	if(!prs_align(ps))
		return False;
	
	if(!prs_uint32("mask", ps, depth, &(t->mask)))
		return False;

	return True;
}

/*******************************************************************
 Check if ACE has OBJECT type.
********************************************************************/

BOOL sec_ace_object(uint8 type)
{
	if (type == SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT ||
            type == SEC_ACE_TYPE_ACCESS_DENIED_OBJECT ||
            type == SEC_ACE_TYPE_SYSTEM_AUDIT_OBJECT ||
            type == SEC_ACE_TYPE_SYSTEM_ALARM_OBJECT) {
		return True;
	}
	return False;
}

/*******************************************************************
 copy a SEC_ACE structure.
********************************************************************/
void sec_ace_copy(SEC_ACE *ace_dest, SEC_ACE *ace_src)
{
	ace_dest->type  = ace_src->type;
	ace_dest->flags = ace_src->flags;
	ace_dest->size  = ace_src->size;
	ace_dest->info.mask = ace_src->info.mask;
	ace_dest->obj_flags = ace_src->obj_flags;
	memcpy(&ace_dest->obj_guid, &ace_src->obj_guid, GUID_SIZE);
	memcpy(&ace_dest->inh_guid, &ace_src->inh_guid, GUID_SIZE);	
	sid_copy(&ace_dest->trustee, &ace_src->trustee);
}

/*******************************************************************
 Sets up a SEC_ACE structure.
********************************************************************/

void init_sec_ace(SEC_ACE *t, DOM_SID *sid, uint8 type, SEC_ACCESS mask, uint8 flag)
{
	t->type = type;
	t->flags = flag;
	t->size = sid_size(sid) + 8;
	t->info = mask;

	ZERO_STRUCTP(&t->trustee);
	sid_copy(&t->trustee, sid);
}

/*******************************************************************
 Reads or writes a SEC_ACE structure.
********************************************************************/

BOOL sec_io_ace(char *desc, SEC_ACE *psa, prs_struct *ps, int depth)
{
	uint32 old_offset;
	uint32 offset_ace_size;

	if (psa == NULL)
		return False;

	prs_debug(ps, depth, desc, "sec_io_ace");
	depth++;

	if(!prs_align(ps))
		return False;
	
	old_offset = prs_offset(ps);

	if(!prs_uint8("type ", ps, depth, &psa->type))
		return False;

	if(!prs_uint8("flags", ps, depth, &psa->flags))
		return False;

	if(!prs_uint16_pre("size ", ps, depth, &psa->size, &offset_ace_size))
		return False;

	if(!sec_io_access("info ", &psa->info, ps, depth))
		return False;

	if(!prs_align(ps))
		return False;

	/* check whether object access is present */
	if (!sec_ace_object(psa->type)) {
		if (!smb_io_dom_sid("trustee  ", &psa->trustee , ps, depth))
			return False;
	} else {
		if (!prs_uint32("obj_flags", ps, depth, &psa->obj_flags))
			return False;

		if (psa->obj_flags & SEC_ACE_OBJECT_PRESENT)
			if (!prs_uint8s(False, "obj_guid", ps, depth, psa->obj_guid.info, GUID_SIZE))
				return False;

		if (psa->obj_flags & SEC_ACE_OBJECT_INHERITED_PRESENT)
			if (!prs_uint8s(False, "inh_guid", ps, depth, psa->inh_guid.info, GUID_SIZE))
				return False;

		if(!smb_io_dom_sid("trustee  ", &psa->trustee , ps, depth))
			return False;
	}

	if(!prs_uint16_post("size ", ps, depth, &psa->size, offset_ace_size, old_offset))
		return False;
	return True;
}

/*******************************************************************
 adds new SID with its permissions to ACE list
********************************************************************/

NTSTATUS sec_ace_add_sid(TALLOC_CTX *ctx, SEC_ACE **new, SEC_ACE *old, size_t *num, DOM_SID *sid, uint32 mask)
{
	int i = 0;
	
	if (!ctx || !new || !old || !sid || !num)  return NT_STATUS_INVALID_PARAMETER;

	*num += 1;
	
	if((new[0] = (SEC_ACE *) talloc_zero(ctx, *num * sizeof(SEC_ACE))) == 0)
		return NT_STATUS_NO_MEMORY;

	for (i = 0; i < *num - 1; i ++)
		sec_ace_copy(&(*new)[i], &old[i]);

	(*new)[i].type  = 0;
	(*new)[i].flags = 0;
	(*new)[i].size  = SEC_ACE_HEADER_SIZE + sid_size(sid);
	(*new)[i].info.mask = mask;
	sid_copy(&(*new)[i].trustee, sid);
	return NT_STATUS_OK;
}

/*******************************************************************
  modify SID's permissions at ACL 
********************************************************************/

NTSTATUS sec_ace_mod_sid(SEC_ACE *ace, size_t num, DOM_SID *sid, uint32 mask)
{
	int i = 0;

	if (!ace || !sid)  return NT_STATUS_INVALID_PARAMETER;

	for (i = 0; i < num; i ++) {
		if (sid_compare(&ace[i].trustee, sid) == 0) {
			ace[i].info.mask = mask;
			return NT_STATUS_OK;
		}
	}
	return NT_STATUS_NOT_FOUND;
}

/*******************************************************************
 delete SID from ACL
********************************************************************/

NTSTATUS sec_ace_del_sid(TALLOC_CTX *ctx, SEC_ACE **new, SEC_ACE *old, size_t *num, DOM_SID *sid)
{
	int i     = 0;
	int n_del = 0;

	if (!ctx || !new || !old || !sid || !num)  return NT_STATUS_INVALID_PARAMETER;

	if((new[0] = (SEC_ACE *) talloc_zero(ctx, *num * sizeof(SEC_ACE))) == 0)
		return NT_STATUS_NO_MEMORY;

	for (i = 0; i < *num; i ++) {
		if (sid_compare(&old[i].trustee, sid) != 0)
			sec_ace_copy(&(*new)[i], &old[i]);
		else
			n_del ++;
	}
	if (n_del == 0)
		return NT_STATUS_NOT_FOUND;
	else {
		*num -= n_del;
		return NT_STATUS_OK;
	}
}

/*******************************************************************
 Create a SEC_ACL structure.  
********************************************************************/

SEC_ACL *make_sec_acl(TALLOC_CTX *ctx, uint16 revision, int num_aces, SEC_ACE *ace_list)
{
	SEC_ACL *dst;
	int i;

	if((dst = (SEC_ACL *)talloc_zero(ctx,sizeof(SEC_ACL))) == NULL)
		return NULL;

	dst->revision = revision;
	dst->num_aces = num_aces;
	dst->size = SEC_ACL_HEADER_SIZE;

	/* Now we need to return a non-NULL address for the ace list even
	   if the number of aces required is zero.  This is because there
	   is a distinct difference between a NULL ace and an ace with zero
	   entries in it.  This is achieved by checking that num_aces is a
	   positive number. */

	if ((num_aces) && 
            ((dst->ace = (SEC_ACE *)talloc(ctx, sizeof(SEC_ACE) * num_aces)) 
             == NULL)) {
		return NULL;
	}
        
	for (i = 0; i < num_aces; i++) {
		dst->ace[i] = ace_list[i]; /* Structure copy. */
		dst->size += ace_list[i].size;
	}

	return dst;
}

/*******************************************************************
 Duplicate a SEC_ACL structure.  
********************************************************************/

SEC_ACL *dup_sec_acl(TALLOC_CTX *ctx, SEC_ACL *src)
{
	if(src == NULL)
		return NULL;

	return make_sec_acl(ctx, src->revision, src->num_aces, src->ace);
}

/*******************************************************************
 Reads or writes a SEC_ACL structure.  

 First of the xx_io_xx functions that allocates its data structures
 for you as it reads them.
********************************************************************/

BOOL sec_io_acl(char *desc, SEC_ACL **ppsa, prs_struct *ps, int depth)
{
	int i;
	uint32 old_offset;
	uint32 offset_acl_size;
	SEC_ACL *psa;

	if (ppsa == NULL)
		return False;

	psa = *ppsa;

	if(UNMARSHALLING(ps) && psa == NULL) {
		/*
		 * This is a read and we must allocate the stuct to read into.
		 */
		if((psa = (SEC_ACL *)prs_alloc_mem(ps, sizeof(SEC_ACL))) == NULL)
			return False;
		*ppsa = psa;
	}

	prs_debug(ps, depth, desc, "sec_io_acl");
	depth++;

	if(!prs_align(ps))
		return False;
	
	old_offset = prs_offset(ps);

	if(!prs_uint16("revision", ps, depth, &psa->revision))
		return False;

	if(!prs_uint16_pre("size     ", ps, depth, &psa->size, &offset_acl_size))
		return False;

	if(!prs_uint32("num_aces ", ps, depth, &psa->num_aces))
		return False;

	if (UNMARSHALLING(ps)) {
		/*
		 * Even if the num_aces is zero, allocate memory as there's a difference
		 * between a non-present DACL (allow all access) and a DACL with no ACE's
		 * (allow no access).
		 */
		if((psa->ace = (SEC_ACE *)prs_alloc_mem(ps,sizeof(psa->ace[0]) * (psa->num_aces+1))) == NULL)
			return False;
	}

	for (i = 0; i < psa->num_aces; i++) {
		fstring tmp;
		slprintf(tmp, sizeof(tmp)-1, "ace_list[%02d]: ", i);
		if(!sec_io_ace(tmp, &psa->ace[i], ps, depth))
			return False;
	}

	if(!prs_align(ps))
		return False;

	if(!prs_uint16_post("size     ", ps, depth, &psa->size, offset_acl_size, old_offset))
		return False;

	return True;
}

/*******************************************************************
 Works out the linearization size of a SEC_DESC.
********************************************************************/

size_t sec_desc_size(SEC_DESC *psd)
{
	size_t offset;

	if (!psd) return 0;

	offset = SEC_DESC_HEADER_SIZE;

	if (psd->owner_sid != NULL)
		offset += ((sid_size(psd->owner_sid) + 3) & ~3);

	if (psd->grp_sid != NULL)
		offset += ((sid_size(psd->grp_sid) + 3) & ~3);

	if (psd->sacl != NULL)
		offset += ((psd->sacl->size + 3) & ~3);

	if (psd->dacl != NULL)
		offset += ((psd->dacl->size + 3) & ~3);

	return offset;
}

/*******************************************************************
 Compares two SEC_ACE structures
********************************************************************/

BOOL sec_ace_equal(SEC_ACE *s1, SEC_ACE *s2)
{
	/* Trivial case */

	if (!s1 && !s2) return True;

	/* Check top level stuff */

	if (s1->type != s2->type || s1->flags != s2->flags ||
	    s1->info.mask != s2->info.mask) {
		return False;
	}

	/* Check SID */

	if (!sid_equal(&s1->trustee, &s2->trustee)) {
		return False;
	}

	return True;
}

/*******************************************************************
 Compares two SEC_ACL structures
********************************************************************/

BOOL sec_acl_equal(SEC_ACL *s1, SEC_ACL *s2)
{
	int i, j;

	/* Trivial cases */

	if (!s1 && !s2) return True;
	if (!s1 || !s2) return False;

	/* Check top level stuff */

	if (s1->revision != s2->revision) {
		DEBUG(10, ("sec_acl_equal(): revision differs (%d != %d)\n",
			   s1->revision, s2->revision));
		return False;
	}

	if (s1->num_aces != s2->num_aces) {
		DEBUG(10, ("sec_acl_equal(): num_aces differs (%d != %d)\n",
			   s1->revision, s2->revision));
		return False;
	}

	/* The ACEs could be in any order so check each ACE in s1 against 
	   each ACE in s2. */

	for (i = 0; i < s1->num_aces; i++) {
		BOOL found = False;

		for (j = 0; j < s2->num_aces; j++) {
			if (sec_ace_equal(&s1->ace[i], &s2->ace[j])) {
				found = True;
				break;
			}
		}

		if (!found) return False;
	}

	return True;
}

/*******************************************************************
 Compares two SEC_DESC structures
********************************************************************/

BOOL sec_desc_equal(SEC_DESC *s1, SEC_DESC *s2)
{
	/* Trivial case */

	if (!s1 && !s2) {
		goto done;
	}

	/* Check top level stuff */

	if (s1->revision != s2->revision) {
		DEBUG(10, ("sec_desc_equal(): revision differs (%d != %d)\n",
			   s1->revision, s2->revision));
		return False;
	}

	if (s1->type!= s2->type) {
		DEBUG(10, ("sec_desc_equal(): type differs (%d != %d)\n",
			   s1->type, s2->type));
		return False;
	}

	/* Check owner and group */

	if (!sid_equal(s1->owner_sid, s2->owner_sid)) {
		fstring str1, str2;

		sid_to_string(str1, s1->owner_sid);
		sid_to_string(str2, s2->owner_sid);

		DEBUG(10, ("sec_desc_equal(): owner differs (%s != %s)\n",
			   str1, str2));
		return False;
	}

	if (!sid_equal(s1->grp_sid, s2->grp_sid)) {
		fstring str1, str2;

		sid_to_string(str1, s1->grp_sid);
		sid_to_string(str2, s2->grp_sid);

		DEBUG(10, ("sec_desc_equal(): group differs (%s != %s)\n",
			   str1, str2));
		return False;
	}

	/* Check ACLs present in one but not the other */

	if ((s1->dacl && !s2->dacl) || (!s1->dacl && s2->dacl) ||
	    (s1->sacl && !s2->sacl) || (!s1->sacl && s2->sacl)) {
		DEBUG(10, ("sec_desc_equal(): dacl or sacl not present\n"));
		return False;
	}

	/* Sigh - we have to do it the hard way by iterating over all
	   the ACEs in the ACLs */

	if (!sec_acl_equal(s1->dacl, s2->dacl) ||
	    !sec_acl_equal(s1->sacl, s2->sacl)) {
		DEBUG(10, ("sec_desc_equal(): dacl/sacl list not equal\n"));
		return False;
	}

 done:
	DEBUG(10, ("sec_desc_equal(): secdescs are identical\n"));
	return True;
}

/*******************************************************************
 Merge part of security descriptor old_sec in to the empty sections of 
 security descriptor new_sec.
********************************************************************/

SEC_DESC_BUF *sec_desc_merge(TALLOC_CTX *ctx, SEC_DESC_BUF *new_sdb, SEC_DESC_BUF *old_sdb)
{
	DOM_SID *owner_sid, *group_sid;
	SEC_DESC_BUF *return_sdb;
	SEC_ACL *dacl, *sacl;
	SEC_DESC *psd = NULL;
	uint16 secdesc_type;
	size_t secdesc_size;

	/* Copy over owner and group sids.  There seems to be no flag for
	   this so just check the pointer values. */

	owner_sid = new_sdb->sec->owner_sid ? new_sdb->sec->owner_sid :
		old_sdb->sec->owner_sid;

	group_sid = new_sdb->sec->grp_sid ? new_sdb->sec->grp_sid :
		old_sdb->sec->grp_sid;
	
	secdesc_type = new_sdb->sec->type;

	/* Ignore changes to the system ACL.  This has the effect of making
	   changes through the security tab audit button not sticking. 
	   Perhaps in future Samba could implement these settings somehow. */

	sacl = NULL;
	secdesc_type &= ~SEC_DESC_SACL_PRESENT;

	/* Copy across discretionary ACL */

	if (secdesc_type & SEC_DESC_DACL_PRESENT) {
		dacl = new_sdb->sec->dacl;
	} else {
		dacl = old_sdb->sec->dacl;
	}

	/* Create new security descriptor from bits */

	psd = make_sec_desc(ctx, new_sdb->sec->revision, 
			    owner_sid, group_sid, sacl, dacl, &secdesc_size);

	return_sdb = make_sec_desc_buf(ctx, secdesc_size, psd);

	return(return_sdb);
}

/*******************************************************************
 Tallocs a duplicate SID. 
********************************************************************/ 

static DOM_SID *sid_dup_talloc(TALLOC_CTX *ctx, DOM_SID *src)
{
  DOM_SID *dst;

  if(!src)
    return NULL;

  if((dst = talloc_zero(ctx, sizeof(DOM_SID))) != NULL) {
    sid_copy( dst, src);
  }

  return dst;
}

/*******************************************************************
 Creates a SEC_DESC structure
********************************************************************/

SEC_DESC *make_sec_desc(TALLOC_CTX *ctx, uint16 revision, 
			DOM_SID *owner_sid, DOM_SID *grp_sid,
			SEC_ACL *sacl, SEC_ACL *dacl, size_t *sd_size)
{
	SEC_DESC *dst;
	uint32 offset     = 0;
	uint32 offset_sid = SEC_DESC_HEADER_SIZE;
	uint32 offset_acl = 0;

	*sd_size = 0;

	if(( dst = (SEC_DESC *)talloc_zero(ctx, sizeof(SEC_DESC))) == NULL)
		return NULL;

	dst->revision = revision;
	dst->type     = SEC_DESC_SELF_RELATIVE;

	if (sacl) dst->type |= SEC_DESC_SACL_PRESENT;
	if (dacl) dst->type |= SEC_DESC_DACL_PRESENT;

	dst->off_owner_sid = 0;
	dst->off_grp_sid   = 0;
	dst->off_sacl      = 0;
	dst->off_dacl      = 0;

	if(owner_sid && ((dst->owner_sid = sid_dup_talloc(ctx,owner_sid)) == NULL))
		goto error_exit;

	if(grp_sid && ((dst->grp_sid = sid_dup_talloc(ctx,grp_sid)) == NULL))
		goto error_exit;

	if(sacl && ((dst->sacl = dup_sec_acl(ctx, sacl)) == NULL))
		goto error_exit;

	if(dacl && ((dst->dacl = dup_sec_acl(ctx, dacl)) == NULL))
		goto error_exit;

	offset = 0;

	/*
	 * Work out the linearization sizes.
	 */
	if (dst->owner_sid != NULL) {

		if (offset == 0)
			offset = SEC_DESC_HEADER_SIZE;

		offset += ((sid_size(dst->owner_sid) + 3) & ~3);
	}

	if (dst->grp_sid != NULL) {

		if (offset == 0)
			offset = SEC_DESC_HEADER_SIZE;

		offset += ((sid_size(dst->grp_sid) + 3) & ~3);
	}

	if (dst->sacl != NULL) {

		offset_acl = SEC_DESC_HEADER_SIZE;

		dst->off_sacl  = offset_acl;
		offset_acl    += ((dst->sacl->size + 3) & ~3);
		offset        += dst->sacl->size;
		offset_sid    += dst->sacl->size;
	}

	if (dst->dacl != NULL) {

		if (offset_acl == 0)
			offset_acl = SEC_DESC_HEADER_SIZE;

		dst->off_dacl  = offset_acl;
		offset_acl    += ((dst->dacl->size + 3) & ~3);
		offset        += dst->dacl->size;
		offset_sid    += dst->dacl->size;
	}

	*sd_size = (size_t)((offset == 0) ? SEC_DESC_HEADER_SIZE : offset);

	dst->off_owner_sid = offset_sid;

	if (dst->owner_sid != NULL)
		dst->off_grp_sid = offset_sid + sid_size(dst->owner_sid);
	else
		dst->off_grp_sid = offset_sid;

	return dst;

error_exit:

	*sd_size = 0;
	return NULL;
}

/*******************************************************************
 Duplicate a SEC_DESC structure.  
********************************************************************/

SEC_DESC *dup_sec_desc( TALLOC_CTX *ctx, SEC_DESC *src)
{
	size_t dummy;

	if(src == NULL)
		return NULL;

	return make_sec_desc( ctx, src->revision, 
				src->owner_sid, src->grp_sid, src->sacl,
				src->dacl, &dummy);
}

/*******************************************************************
 Creates a SEC_DESC structure with typical defaults.
********************************************************************/

SEC_DESC *make_standard_sec_desc(TALLOC_CTX *ctx, DOM_SID *owner_sid, DOM_SID *grp_sid,
				 SEC_ACL *dacl, size_t *sd_size)
{
	return make_sec_desc(ctx, SEC_DESC_REVISION,
			     owner_sid, grp_sid, NULL, dacl, sd_size);
}

/*******************************************************************
 Reads or writes a SEC_DESC structure.
 If reading and the *ppsd = NULL, allocates the structure.
********************************************************************/

BOOL sec_io_desc(char *desc, SEC_DESC **ppsd, prs_struct *ps, int depth)
{
	uint32 old_offset;
	uint32 max_offset = 0; /* after we're done, move offset to end */
	uint32 tmp_offset = 0;
	
	SEC_DESC *psd;

	if (ppsd == NULL)
		return False;

	psd = *ppsd;

	if (psd == NULL) {
		if(UNMARSHALLING(ps)) {
			if((psd = (SEC_DESC *)prs_alloc_mem(ps,sizeof(SEC_DESC))) == NULL)
				return False;
			*ppsd = psd;
		} else {
			/* Marshalling - just ignore. */
			return True;
		}
	}

	prs_debug(ps, depth, desc, "sec_io_desc");
	depth++;

	if(!prs_align(ps))
		return False;
	
	/* start of security descriptor stored for back-calc offset purposes */
	old_offset = prs_offset(ps);

	if(!prs_uint16("revision ", ps, depth, &psd->revision))
		return False;

	if(!prs_uint16("type     ", ps, depth, &psd->type))
		return False;

	if(!prs_uint32("off_owner_sid", ps, depth, &psd->off_owner_sid))
		return False;

	if(!prs_uint32("off_grp_sid  ", ps, depth, &psd->off_grp_sid))
		return False;

	if(!prs_uint32("off_sacl     ", ps, depth, &psd->off_sacl))
		return False;

	if(!prs_uint32("off_dacl     ", ps, depth, &psd->off_dacl))
		return False;

	max_offset = MAX(max_offset, prs_offset(ps));

	if (psd->off_owner_sid != 0) {

		if (UNMARSHALLING(ps)) {
			if(!prs_set_offset(ps, old_offset + psd->off_owner_sid))
				return False;
			/* reading */
			if((psd->owner_sid = (DOM_SID *)prs_alloc_mem(ps,sizeof(*psd->owner_sid))) == NULL)
				return False;
		}

		tmp_offset = ps->data_offset;
		ps->data_offset = psd->off_owner_sid;

		if(!smb_io_dom_sid("owner_sid ", psd->owner_sid , ps, depth))
			return False;
		if(!prs_align(ps))
			return False;

		ps->data_offset = tmp_offset;
	}

	max_offset = MAX(max_offset, prs_offset(ps));

	if (psd->off_grp_sid != 0) {

		if (UNMARSHALLING(ps)) {
			/* reading */
			if(!prs_set_offset(ps, old_offset + psd->off_grp_sid))
				return False;
			if((psd->grp_sid = (DOM_SID *)prs_alloc_mem(ps,sizeof(*psd->grp_sid))) == NULL)
				return False;
		}

		tmp_offset = ps->data_offset;
		ps->data_offset = psd->off_grp_sid;

		if(!smb_io_dom_sid("grp_sid", psd->grp_sid, ps, depth))
			return False;
		if(!prs_align(ps))
			return False;

		ps->data_offset = tmp_offset;
	}

	max_offset = MAX(max_offset, prs_offset(ps));

	if ((psd->type & SEC_DESC_SACL_PRESENT) && psd->off_sacl) {
		if(!prs_set_offset(ps, old_offset + psd->off_sacl))
			return False;
		if(!sec_io_acl("sacl", &psd->sacl, ps, depth))
			return False;
		if(!prs_align(ps))
			return False;
	}

	max_offset = MAX(max_offset, prs_offset(ps));

	if ((psd->type & SEC_DESC_DACL_PRESENT) && psd->off_dacl != 0) {
		if(!prs_set_offset(ps, old_offset + psd->off_dacl))
			return False;
		if(!sec_io_acl("dacl", &psd->dacl, ps, depth))
			return False;
		if(!prs_align(ps))
			return False;
	}

	max_offset = MAX(max_offset, prs_offset(ps));

	if(!prs_set_offset(ps, max_offset))
		return False;
	return True;
}

/*******************************************************************
 Creates a SEC_DESC_BUF structure.
********************************************************************/

SEC_DESC_BUF *make_sec_desc_buf(TALLOC_CTX *ctx, size_t len, SEC_DESC *sec_desc)
{
	SEC_DESC_BUF *dst;

	if((dst = (SEC_DESC_BUF *)talloc_zero(ctx, sizeof(SEC_DESC_BUF))) == NULL)
		return NULL;

	/* max buffer size (allocated size) */
	dst->max_len = (uint32)len;
	dst->len = (uint32)len;
	
	if(sec_desc && ((dst->sec = dup_sec_desc(ctx, sec_desc)) == NULL)) {
		return NULL;
	}

	dst->ptr = 0x1;

	return dst;
}

/*******************************************************************
 Duplicates a SEC_DESC_BUF structure.
********************************************************************/

SEC_DESC_BUF *dup_sec_desc_buf(TALLOC_CTX *ctx, SEC_DESC_BUF *src)
{
	if(src == NULL)
		return NULL;

	return make_sec_desc_buf( ctx, src->len, src->sec);
}

/*******************************************************************
 Reads or writes a SEC_DESC_BUF structure.
********************************************************************/

BOOL sec_io_desc_buf(char *desc, SEC_DESC_BUF **ppsdb, prs_struct *ps, int depth)
{
	uint32 off_len;
	uint32 off_max_len;
	uint32 old_offset;
	uint32 size;
	SEC_DESC_BUF *psdb;

	if (ppsdb == NULL)
		return False;

	psdb = *ppsdb;

	if (UNMARSHALLING(ps) && psdb == NULL) {
		if((psdb = (SEC_DESC_BUF *)prs_alloc_mem(ps,sizeof(SEC_DESC_BUF))) == NULL)
			return False;
		*ppsdb = psdb;
	}

	prs_debug(ps, depth, desc, "sec_io_desc_buf");
	depth++;

	if(!prs_align(ps))
		return False;
	
	if(!prs_uint32_pre("max_len", ps, depth, &psdb->max_len, &off_max_len))
		return False;

	if(!prs_uint32    ("ptr  ", ps, depth, &psdb->ptr))
		return False;

	if(!prs_uint32_pre("len    ", ps, depth, &psdb->len, &off_len))
		return False;

	old_offset = prs_offset(ps);

	/* reading, length is non-zero; writing, descriptor is non-NULL */
	if ((UNMARSHALLING(ps) && psdb->len != 0) || (MARSHALLING(ps) && psdb->sec != NULL)) {
		if(!sec_io_desc("sec   ", &psdb->sec, ps, depth))
			return False;
	}

	if(!prs_align(ps))
		return False;
	
	size = prs_offset(ps) - old_offset;
	if(!prs_uint32_post("max_len", ps, depth, &psdb->max_len, off_max_len, size == 0 ? psdb->max_len : size))
		return False;

	if(!prs_uint32_post("len    ", ps, depth, &psdb->len, off_len, size))
		return False;

	return True;
}

/*******************************************************************
 adds new SID with its permissions to SEC_DESC
********************************************************************/

NTSTATUS sec_desc_add_sid(TALLOC_CTX *ctx, SEC_DESC **psd, DOM_SID *sid, uint32 mask, size_t *sd_size)
{
	SEC_DESC *sd   = 0;
	SEC_ACL  *dacl = 0;
	SEC_ACE  *ace  = 0;
	NTSTATUS  status;

	*sd_size = 0;

	if (!ctx || !psd || !sid || !sd_size)  return NT_STATUS_INVALID_PARAMETER;

	status = sec_ace_add_sid(ctx, &ace, psd[0]->dacl->ace, &psd[0]->dacl->num_aces, sid, mask);
	
	if (!NT_STATUS_IS_OK(status))
		return status;

	if (!(dacl = make_sec_acl(ctx, psd[0]->dacl->revision, psd[0]->dacl->num_aces, ace)))
		return NT_STATUS_UNSUCCESSFUL;
	
	if (!(sd = make_sec_desc(ctx, psd[0]->revision, psd[0]->owner_sid, 
		psd[0]->grp_sid, psd[0]->sacl, dacl, sd_size)))
		return NT_STATUS_UNSUCCESSFUL;

	*psd = sd;
	 sd  = 0;
	return NT_STATUS_OK;
}

/*******************************************************************
 modify SID's permissions at SEC_DESC
********************************************************************/

NTSTATUS sec_desc_mod_sid(SEC_DESC *sd, DOM_SID *sid, uint32 mask)
{
	NTSTATUS status;

	if (!sd || !sid) return NT_STATUS_INVALID_PARAMETER;

	status = sec_ace_mod_sid(sd->dacl->ace, sd->dacl->num_aces, sid, mask);

	if (!NT_STATUS_IS_OK(status))
		return status;
	
	return NT_STATUS_OK;
}

/*******************************************************************
 delete SID from SEC_DESC
********************************************************************/

NTSTATUS sec_desc_del_sid(TALLOC_CTX *ctx, SEC_DESC **psd, DOM_SID *sid, size_t *sd_size)
{
	SEC_DESC *sd   = 0;
	SEC_ACL  *dacl = 0;
	SEC_ACE  *ace  = 0;
	NTSTATUS  status;

	*sd_size = 0;
	
	if (!ctx || !psd[0] || !sid || !sd_size) return NT_STATUS_INVALID_PARAMETER;

	status = sec_ace_del_sid(ctx, &ace, psd[0]->dacl->ace, &psd[0]->dacl->num_aces, sid);

	if (!NT_STATUS_IS_OK(status))
		return status;

	if (!(dacl = make_sec_acl(ctx, psd[0]->dacl->revision, psd[0]->dacl->num_aces, ace)))
		return NT_STATUS_UNSUCCESSFUL;
	
	if (!(sd = make_sec_desc(ctx, psd[0]->revision, psd[0]->owner_sid, 
		psd[0]->grp_sid, psd[0]->sacl, dacl, sd_size)))
		return NT_STATUS_UNSUCCESSFUL;

	*psd = sd;
	 sd  = 0;
	return NT_STATUS_OK;
}