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/*
Unix SMB/CIFS implementation.
security access checking routines
Copyright (C) Andrew Tridgell 2004
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"
#include "librpc/gen_ndr/ndr_security.h"
/*
check if a sid is in the supplied token
*/
static BOOL sid_active_in_token(const struct dom_sid *sid,
const struct security_token *token)
{
int i;
for (i=0;i<token->num_sids;i++) {
if (dom_sid_equal(sid, token->sids[i])) {
return True;
}
}
return False;
}
/*
perform a SEC_FLAG_MAXIMUM_ALLOWED access check
*/
static uint32_t access_check_max_allowed(const struct security_descriptor *sd,
const struct security_token *token)
{
uint32_t denied = 0, granted = 0;
unsigned i;
if (sid_active_in_token(sd->owner_sid, token)) {
granted |= SEC_STD_WRITE_DAC | SEC_STD_READ_CONTROL | SEC_STD_DELETE;
} else if (sec_privilege_check(token, SEC_PRIV_RESTORE)) {
granted |= SEC_STD_DELETE;
}
for (i = 0;i<sd->dacl->num_aces; i++) {
struct security_ace *ace = &sd->dacl->aces[i];
if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
continue;
}
if (!sid_active_in_token(&ace->trustee, token)) {
continue;
}
switch (ace->type) {
case SEC_ACE_TYPE_ACCESS_ALLOWED:
granted |= ace->access_mask;
break;
case SEC_ACE_TYPE_ACCESS_DENIED:
case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
denied |= ace->access_mask;
break;
default: /* Other ACE types not handled/supported */
break;
}
}
return granted & ~denied;
}
/*
the main entry point for access checking.
*/
NTSTATUS sec_access_check(const struct security_descriptor *sd,
const struct security_token *token,
uint32_t access_desired,
uint32_t *access_granted)
{
int i;
uint32_t bits_remaining;
*access_granted = access_desired;
bits_remaining = access_desired;
/* handle the maximum allowed flag */
if (access_desired & SEC_FLAG_MAXIMUM_ALLOWED) {
access_desired |= access_check_max_allowed(sd, token);
access_desired &= ~SEC_FLAG_MAXIMUM_ALLOWED;
*access_granted = access_desired;
bits_remaining = access_desired & ~SEC_STD_DELETE;
}
if (access_desired & SEC_FLAG_SYSTEM_SECURITY) {
if (sec_privilege_check(token, SEC_PRIV_SECURITY)) {
bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
} else {
return NT_STATUS_ACCESS_DENIED;
}
}
/* dacl not present allows access */
if (!(sd->type & SEC_DESC_DACL_PRESENT)) {
*access_granted = access_desired;
return NT_STATUS_OK;
}
/* empty dacl denies access */
if (sd->dacl == NULL || sd->dacl->num_aces == 0) {
return NT_STATUS_ACCESS_DENIED;
}
/* the owner always gets SEC_STD_WRITE_DAC, SEC_STD_READ_CONTROL and SEC_STD_DELETE */
if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE)) &&
sid_active_in_token(sd->owner_sid, token)) {
bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
}
if ((bits_remaining & SEC_STD_DELETE) &&
sec_privilege_check(token, SEC_PRIV_RESTORE)) {
bits_remaining &= ~SEC_STD_DELETE;
}
/* check each ace in turn. */
for (i=0; bits_remaining && i < sd->dacl->num_aces; i++) {
struct security_ace *ace = &sd->dacl->aces[i];
if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
continue;
}
if (!sid_active_in_token(&ace->trustee, token)) {
continue;
}
switch (ace->type) {
case SEC_ACE_TYPE_ACCESS_ALLOWED:
bits_remaining &= ~ace->access_mask;
break;
case SEC_ACE_TYPE_ACCESS_DENIED:
case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
if (bits_remaining & ace->access_mask) {
return NT_STATUS_ACCESS_DENIED;
}
break;
default: /* Other ACE types not handled/supported */
break;
}
}
if (bits_remaining != 0) {
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}
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