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samba-mirror/libcli/security/access_check.c
Stefan Metzmacher 4928d66fc2 libcli/security: make sure that we don't grant SEC_STD_DELETE to the owner by default
In the file server SEC_STD_DELETE is granted on the file/directory
or by FILE_DELETE_CHILD on the parent directory.

metze

Autobuild-User: Stefan Metzmacher <metze@samba.org>
Autobuild-Date: Mon Mar 21 23:25:05 CET 2011 on sn-devel-104
2011-03-21 23:25:05 +01:00

407 lines
12 KiB
C

/*
Unix SMB/CIFS implementation.
Copyright (C) Andrew Tridgell 2004
Copyright (C) Gerald Carter 2005
Copyright (C) Volker Lendecke 2007
Copyright (C) Jeremy Allison 2008
Copyright (C) Andrew Bartlett 2010
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"
/* Map generic access rights to object specific rights. This technique is
used to give meaning to assigning read, write, execute and all access to
objects. Each type of object has its own mapping of generic to object
specific access rights. */
void se_map_generic(uint32_t *access_mask, const struct generic_mapping *mapping)
{
uint32_t old_mask = *access_mask;
if (*access_mask & GENERIC_READ_ACCESS) {
*access_mask &= ~GENERIC_READ_ACCESS;
*access_mask |= mapping->generic_read;
}
if (*access_mask & GENERIC_WRITE_ACCESS) {
*access_mask &= ~GENERIC_WRITE_ACCESS;
*access_mask |= mapping->generic_write;
}
if (*access_mask & GENERIC_EXECUTE_ACCESS) {
*access_mask &= ~GENERIC_EXECUTE_ACCESS;
*access_mask |= mapping->generic_execute;
}
if (*access_mask & GENERIC_ALL_ACCESS) {
*access_mask &= ~GENERIC_ALL_ACCESS;
*access_mask |= mapping->generic_all;
}
if (old_mask != *access_mask) {
DEBUG(10, ("se_map_generic(): mapped mask 0x%08x to 0x%08x\n",
old_mask, *access_mask));
}
}
/* Map generic access rights to object specific rights for all the ACE's
* in a security_acl.
*/
void security_acl_map_generic(struct security_acl *sa,
const struct generic_mapping *mapping)
{
unsigned int i;
if (!sa) {
return;
}
for (i = 0; i < sa->num_aces; i++) {
se_map_generic(&sa->aces[i].access_mask, mapping);
}
}
/* Map standard access rights to object specific rights. This technique is
used to give meaning to assigning read, write, execute and all access to
objects. Each type of object has its own mapping of standard to object
specific access rights. */
void se_map_standard(uint32_t *access_mask, const struct standard_mapping *mapping)
{
uint32_t old_mask = *access_mask;
if (*access_mask & SEC_STD_READ_CONTROL) {
*access_mask &= ~SEC_STD_READ_CONTROL;
*access_mask |= mapping->std_read;
}
if (*access_mask & (SEC_STD_DELETE|SEC_STD_WRITE_DAC|SEC_STD_WRITE_OWNER|SEC_STD_SYNCHRONIZE)) {
*access_mask &= ~(SEC_STD_DELETE|SEC_STD_WRITE_DAC|SEC_STD_WRITE_OWNER|SEC_STD_SYNCHRONIZE);
*access_mask |= mapping->std_all;
}
if (old_mask != *access_mask) {
DEBUG(10, ("se_map_standard(): mapped mask 0x%08x to 0x%08x\n",
old_mask, *access_mask));
}
}
/*
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;
}
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;
}
/*
The main entry point for access checking. If returning ACCESS_DENIED
this function returns the denied bits in the uint32_t pointed
to by the access_granted pointer.
*/
NTSTATUS se_access_check(const struct security_descriptor *sd,
const struct security_token *token,
uint32_t access_desired,
uint32_t *access_granted)
{
uint32_t 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) {
uint32_t orig_access_desired = access_desired;
access_desired |= access_check_max_allowed(sd, token);
access_desired &= ~SEC_FLAG_MAXIMUM_ALLOWED;
*access_granted = access_desired;
bits_remaining = access_desired;
DEBUG(10,("se_access_check: MAX desired = 0x%x, granted = 0x%x, remaining = 0x%x\n",
orig_access_desired,
*access_granted,
bits_remaining));
}
/* s3 had this with #if 0 previously. To be sure the merge
doesn't change any behaviour, we have the above #if check
on _SAMBA_BUILD_. */
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;
}
}
/* the owner always gets SEC_STD_WRITE_DAC and SEC_STD_READ_CONTROL */
if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL)) &&
security_token_has_sid(token, sd->owner_sid)) {
bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL);
}
/* TODO: remove this, as it is file server specific */
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);
}
/* a NULL dacl allows access */
if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
*access_granted = access_desired;
return NT_STATUS_OK;
}
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) {
*access_granted = bits_remaining;
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}
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;
}
/* 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,
struct dom_sid *replace_sid)
{
uint32_t i;
uint32_t bits_remaining;
struct object_tree *node;
const struct GUID *type;
struct dom_sid *ps_sid = dom_sid_parse_talloc(NULL, SID_NT_SELF);
*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;
}
if (access_desired & SEC_FLAG_SYSTEM_SECURITY) {
if (security_token_has_privilege(token, SEC_PRIV_SECURITY)) {
bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
} else {
talloc_free(ps_sid);
return NT_STATUS_PRIVILEGE_NOT_HELD;
}
}
/* the owner always gets SEC_STD_WRITE_DAC and SEC_STD_READ_CONTROL */
if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL)) &&
security_token_has_sid(token, sd->owner_sid)) {
bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL);
}
/* TODO: remove this, as it is file server specific */
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);
}
/* a NULL dacl allows access */
if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
*access_granted = access_desired;
talloc_free(ps_sid);
return NT_STATUS_OK;
}
if (sd->dacl == NULL) {
goto done;
}
/* check each ace in turn. */
for (i=0; bits_remaining && i < sd->dacl->num_aces; i++) {
struct dom_sid *trustee;
struct security_ace *ace = &sd->dacl->aces[i];
if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
continue;
}
if (dom_sid_equal(&ace->trustee, ps_sid) && replace_sid) {
trustee = replace_sid;
}
else
{
trustee = &ace->trustee;
}
if (!security_token_has_sid(token, 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) {
talloc_free(ps_sid);
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);
if (node->remaining_access == 0) {
talloc_free(ps_sid);
return NT_STATUS_OK;
}
} else {
if (node->remaining_access & ace->access_mask){
talloc_free(ps_sid);
return NT_STATUS_ACCESS_DENIED;
}
}
break;
default: /* Other ACE types not handled/supported */
break;
}
}
done:
talloc_free(ps_sid);
if (bits_remaining != 0) {
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}