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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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "libcli/security/security.h"
/*
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 (security_token_has_sid(token, sd->owner_sid)) {
granted |= SEC_STD_WRITE_DAC | SEC_STD_READ_CONTROL | SEC_STD_DELETE;
} else if (security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
granted |= SEC_STD_DELETE;
}
if (sd->dacl == NULL) {
return granted & ~denied;
}
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 (!security_token_has_sid(token, &ace->trustee)) {
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;
}
static const struct GUID *get_ace_object_type(struct security_ace *ace)
{
struct GUID *type;
if (ace->object.object.flags & SEC_ACE_OBJECT_TYPE_PRESENT)
type = &ace->object.object.type.type;
else if (ace->object.object.flags & SEC_ACE_INHERITED_OBJECT_TYPE_PRESENT)
type = &ace->object.object.inherited_type.inherited_type; /* This doesn't look right. Is something wrong with the IDL? */
else
type = NULL;
return type;
}
/*
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 (security_token_has_privilege(token, SEC_PRIV_SECURITY)) {
bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
} else {
return NT_STATUS_PRIVILEGE_NOT_HELD;
}
}
/* a NULL dacl allows access */
if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
*access_granted = access_desired;
return NT_STATUS_OK;
}
/* 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)) &&
security_token_has_sid(token, sd->owner_sid)) {
bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
}
if ((bits_remaining & SEC_RIGHTS_PRIV_RESTORE) &&
security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
bits_remaining &= ~(SEC_RIGHTS_PRIV_RESTORE);
}
if ((bits_remaining & SEC_RIGHTS_PRIV_BACKUP) &&
security_token_has_privilege(token, SEC_PRIV_BACKUP)) {
bits_remaining &= ~(SEC_RIGHTS_PRIV_BACKUP);
}
if (sd->dacl == NULL) {
goto done;
}
/* 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 (!security_token_has_sid(token, &ace->trustee)) {
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;
}
}
done:
if (bits_remaining != 0) {
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}
/* modified access check for the purposes of DS security
* Lots of code duplication, it will ve united in just one
* function eventually */
NTSTATUS sec_access_check_ds(const struct security_descriptor *sd,
const struct security_token *token,
uint32_t access_desired,
uint32_t *access_granted,
struct object_tree *tree)
{
int i;
uint32_t bits_remaining;
struct object_tree *node;
struct GUID *type;
*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 (security_token_has_privilege(token, SEC_PRIV_SECURITY)) {
bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
} else {
return NT_STATUS_PRIVILEGE_NOT_HELD;
}
}
/* a NULL dacl allows access */
if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
*access_granted = access_desired;
return NT_STATUS_OK;
}
/* 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)) &&
security_token_has_sid(token, sd->owner_sid)) {
bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
}
if ((bits_remaining & SEC_STD_DELETE) &&
security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
bits_remaining &= ~SEC_STD_DELETE;
}
if (sd->dacl == NULL) {
goto done;
}
/* 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 (!security_token_has_sid(token, &ace->trustee)) {
continue;
}
switch (ace->type) {
case SEC_ACE_TYPE_ACCESS_ALLOWED:
if (tree)
object_tree_modify_access(tree, ace->access_mask);
bits_remaining &= ~ace->access_mask;
break;
case SEC_ACE_TYPE_ACCESS_DENIED:
if (bits_remaining & ace->access_mask) {
return NT_STATUS_ACCESS_DENIED;
}
break;
case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
case SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT:
/* check only in case we have provided a tree,
* the ACE has an object type and that type
* is in the tree */
type = get_ace_object_type(ace);
if (!tree)
continue;
if (!type)
node = tree;
else
if (!(node = get_object_tree_by_GUID(tree, type)))
continue;
if (ace->type == SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT){
object_tree_modify_access(node, ace->access_mask);
}
else {
if (node->remaining_access & ace->access_mask){
return NT_STATUS_ACCESS_DENIED;
}
}
break;
default: /* Other ACE types not handled/supported */
break;
}
}
done:
if (bits_remaining != 0) {
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}
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