f9f5545824
1. Ungrant did not check the callers uid which allowed any caller to remove grants to any key. 2. Grants were not removed when a key was deleted. 3. clean_uid did not clear the grant cache of the target uid. This would leave state grants that could have been used by a new app that happend to get the same uid as the one that was previously uninstalled. 4. Various paths did not respect grants: del, exist, getmtime The del path was particularly awkward because it is required by upgradeKeyBlob. This means it must work when a key that needs upgrading is accessed through a grant alias. Bug: 65851049 Merged-In: I6709b7562d47ad6156bee88a9e2d961f8a4a797d Change-Id: I6709b7562d47ad6156bee88a9e2d961f8a4a797d
112 lines
3.6 KiB
C
112 lines
3.6 KiB
C
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef KEYSTORE_PERMISSIONS_H_
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#define KEYSTORE_PERMISSIONS_H_
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#include <unistd.h>
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/* Here are the permissions, actions, users, and the main function. */
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enum perm_t {
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P_GET_STATE = 1 << 0,
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P_GET = 1 << 1,
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P_INSERT = 1 << 2,
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P_DELETE = 1 << 3,
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P_EXIST = 1 << 4,
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P_LIST = 1 << 5,
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P_RESET = 1 << 6,
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P_PASSWORD = 1 << 7,
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P_LOCK = 1 << 8,
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P_UNLOCK = 1 << 9,
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P_IS_EMPTY = 1 << 10,
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P_SIGN = 1 << 11,
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P_VERIFY = 1 << 12,
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P_GRANT = 1 << 13,
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P_DUPLICATE = 1 << 14,
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P_CLEAR_UID = 1 << 15,
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P_ADD_AUTH = 1 << 16,
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P_USER_CHANGED = 1 << 17,
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P_GEN_UNIQUE_ID = 1 << 18,
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};
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const char* get_perm_label(perm_t perm);
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/**
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* Returns the UID that the callingUid should act as. This is here for
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* legacy support of the WiFi and VPN systems and should be removed
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* when WiFi can operate in its own namespace.
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*/
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uid_t get_keystore_euid(uid_t uid);
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bool has_permission(uid_t uid, perm_t perm, pid_t spid);
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/**
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* Returns true if the callingUid is allowed to interact in the targetUid's
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* namespace.
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*/
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bool is_granted_to(uid_t callingUid, uid_t targetUid);
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int configure_selinux();
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/*
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* Keystore grants.
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*
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* What are keystore grants?
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*
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* Keystore grants are a mechanism that allows an app to grant the permission to use one of its
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* keys to an other app.
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*
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* Liftime of a grant:
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*
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* A keystore grant is ephemeral in that is never persistently stored. When the keystore process
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* exits, all grants are lost. Also, grants can be explicitly revoked by the granter by invoking
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* the ungrant operation.
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*
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* What happens when a grant is created?
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*
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* The grant operation expects a valid key alias and the uid of the grantee, i.e., the app that
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* shall be allowed to use the key denoted by the alias. It then makes an entry in the grant store
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* which generates a new alias of the form <alias>_KEYSTOREGRANT_<random_grant_no_>. This grant
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* alias is returned to the caller which can pass the new alias to the grantee. For every grantee,
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* the grant store keeps a set of grants, an entry of which holds the following information:
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* - the owner of the key by uid, aka granter uid,
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* - the original alias of the granted key, and
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* - the random grant number.
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* (See "grant_store.h:class Grant")
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*
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* What happens when a grant is used?
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*
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* Upon any keystore operation that expects an alias, the alias and the caller's uid are used
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* to retrieve a key file. If that fails some operations try to retrieve a key file indirectly
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* through a grant. These operations include:
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* - attestKey
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* - begin
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* - exportKey
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* - get
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* - getKeyCharacteristics
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* - del
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* - exist
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* - getmtime
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* Operations that DO NOT follow the grant indirection are:
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* - import
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* - generate
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* - grant
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* - ungrant
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* Especially, the latter two mean that neither can a grantee transitively grant a granted key
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* to a third, nor can they relinquish access to the key or revoke access to the key by a third.
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*/
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#endif // KEYSTORE_PERMISSIONS_H_
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