1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2019 Microsoft Corporation
4 *
5 * Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
6 *
7 * File: ima_asymmetric_keys.c
8 * Defines an IMA hook to measure asymmetric keys on key
9 * create or update.
10 */
11
12 #include <keys/asymmetric-type.h>
13 #include <linux/user_namespace.h>
14 #include <linux/ima.h>
15 #include "ima.h"
16
17 /**
18 * ima_post_key_create_or_update - measure asymmetric keys
19 * @keyring: keyring to which the key is linked to
20 * @key: created or updated key
21 * @payload: The data used to instantiate or update the key.
22 * @payload_len: The length of @payload.
23 * @flags: key flags
24 * @create: flag indicating whether the key was created or updated
25 *
26 * Keys can only be measured, not appraised.
27 * The payload data used to instantiate or update the key is measured.
28 */
29 void ima_post_key_create_or_update(struct key *keyring, struct key *key,
30 const void *payload, size_t payload_len,
31 unsigned long flags, bool create)
32 {
33 bool queued = false;
34
35 /* Only asymmetric keys are handled by this hook. */
36 if (key->type != &key_type_asymmetric)
37 return;
38
39 if (!payload || (payload_len == 0))
40 return;
41
42 if (ima_should_queue_key())
43 queued = ima_queue_key(keyring, payload, payload_len);
44
45 if (queued)
46 return;
47
48 /*
49 * keyring->description points to the name of the keyring
50 * (such as ".builtin_trusted_keys", ".ima", etc.) to
51 * which the given key is linked to.
52 *
53 * The name of the keyring is passed in the "eventname"
54 * parameter to process_buffer_measurement() and is set
55 * in the "eventname" field in ima_event_data for
56 * the key measurement IMA event.
57 *
58 * The name of the keyring is also passed in the "keyring"
59 * parameter to process_buffer_measurement() to check
60 * if the IMA policy is configured to measure a key linked
61 * to the given keyring.
62 */
63 process_buffer_measurement(&nop_mnt_idmap, NULL, payload, payload_len,
64 keyring->description, KEY_CHECK, 0,
65 keyring->description, false, NULL, 0);
66 }
67
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