integrity/ima/ima_asymmetric_keys.c

0001 // SPDX-License-Identifier: GPL-2.0+
0002 /*
0003  * Copyright (C) 2019 Microsoft Corporation
0004  *
0005  * Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
0006  *
0007  * File: ima_asymmetric_keys.c
0008  *       Defines an IMA hook to measure asymmetric keys on key
0009  *       create or update.
0010  */
0011
0012 #include <keys/asymmetric-type.h>
0013 #include <linux/user_namespace.h>
0014 #include <linux/ima.h>
0015 #include "ima.h"
0016
0017 /**
0018  * ima_post_key_create_or_update - measure asymmetric keys
0019  * @keyring: keyring to which the key is linked to
0020  * @key: created or updated key
0021  * @payload: The data used to instantiate or update the key.
0022  * @payload_len: The length of @payload.
0023  * @flags: key flags
0024  * @create: flag indicating whether the key was created or updated
0025  *
0026  * Keys can only be measured, not appraised.
0027  * The payload data used to instantiate or update the key is measured.
0028  */
0029 void ima_post_key_create_or_update(struct key *keyring, struct key *key,
0030                    const void *payload, size_t payload_len,
0031                    unsigned long flags, bool create)
0032 {
0033     bool queued = false;
0034
0035     /* Only asymmetric keys are handled by this hook. */
0036     if (key->type != &key_type_asymmetric)
0037         return;
0038
0039     if (!payload || (payload_len == 0))
0040         return;
0041
0042     if (ima_should_queue_key())
0043         queued = ima_queue_key(keyring, payload, payload_len);
0044
0045     if (queued)
0046         return;
0047
0048     /*
0049      * keyring->description points to the name of the keyring
0050      * (such as ".builtin_trusted_keys", ".ima", etc.) to
0051      * which the given key is linked to.
0052      *
0053      * The name of the keyring is passed in the "eventname"
0054      * parameter to process_buffer_measurement() and is set
0055      * in the "eventname" field in ima_event_data for
0056      * the key measurement IMA event.
0057      *
0058      * The name of the keyring is also passed in the "keyring"
0059      * parameter to process_buffer_measurement() to check
0060      * if the IMA policy is configured to measure a key linked
0061      * to the given keyring.
0062      */
0063     process_buffer_measurement(&init_user_ns, NULL, payload, payload_len,
0064                    keyring->description, KEY_CHECK, 0,
0065                    keyring->description, false, NULL, 0);
0066 }