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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef KEYSTORE_PERMISSIONS_H_
#define KEYSTORE_PERMISSIONS_H_
#include <unistd.h>
/* Here are the permissions, actions, users, and the main function. */
enum perm_t {
P_GET_STATE = 1 << 0,
P_GET = 1 << 1,
P_INSERT = 1 << 2,
P_DELETE = 1 << 3,
P_EXIST = 1 << 4,
P_LIST = 1 << 5,
P_RESET = 1 << 6,
P_PASSWORD = 1 << 7,
P_LOCK = 1 << 8,
P_UNLOCK = 1 << 9,
P_IS_EMPTY = 1 << 10,
P_SIGN = 1 << 11,
P_VERIFY = 1 << 12,
P_GRANT = 1 << 13,
P_DUPLICATE = 1 << 14,
P_CLEAR_UID = 1 << 15,
P_ADD_AUTH = 1 << 16,
P_USER_CHANGED = 1 << 17,
P_GEN_UNIQUE_ID = 1 << 18,
};
const char* get_perm_label(perm_t perm);
/**
* Returns the UID that the callingUid should act as. This is here for
* legacy support of the WiFi and VPN systems and should be removed
* when WiFi can operate in its own namespace.
*/
uid_t get_keystore_euid(uid_t uid);
/**
* Returns true if the uid/pid/sid has a permission. Checks based on sid if available.
*
* sid may be null on older kernels
*/
bool has_permission(uid_t uid, perm_t perm, pid_t spid, const char* sid);
/**
* Returns true if the callingUid is allowed to interact in the targetUid's
* namespace.
*/
bool is_granted_to(uid_t callingUid, uid_t targetUid);
int configure_selinux();
/*
* Keystore grants.
*
* What are keystore grants?
*
* Keystore grants are a mechanism that allows an app to grant the permission to use one of its
* keys to an other app.
*
* Liftime of a grant:
*
* A keystore grant is ephemeral in that is never persistently stored. When the keystore process
* exits, all grants are lost. Also, grants can be explicitly revoked by the granter by invoking
* the ungrant operation.
*
* What happens when a grant is created?
*
* The grant operation expects a valid key alias and the uid of the grantee, i.e., the app that
* shall be allowed to use the key denoted by the alias. It then makes an entry in the grant store
* which generates a new alias of the form <alias>_KEYSTOREGRANT_<random_grant_no_>. This grant
* alias is returned to the caller which can pass the new alias to the grantee. For every grantee,
* the grant store keeps a set of grants, an entry of which holds the following information:
* - the owner of the key by uid, aka granter uid,
* - the original alias of the granted key, and
* - the random grant number.
* (See "grant_store.h:class Grant")
*
* What happens when a grant is used?
*
* Upon any keystore operation that expects an alias, the alias and the caller's uid are used
* to retrieve a key file. If that fails some operations try to retrieve a key file indirectly
* through a grant. These operations include:
* - attestKey
* - begin
* - exportKey
* - get
* - getKeyCharacteristics
* - del
* - exist
* - getmtime
* Operations that DO NOT follow the grant indirection are:
* - import
* - generate
* - grant
* - ungrant
* Especially, the latter two mean that neither can a grantee transitively grant a granted key
* to a third, nor can they relinquish access to the key or revoke access to the key by a third.
*/
#endif // KEYSTORE_PERMISSIONS_H_
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