From 88e70da170e8945f6b1c1299083d1b942705beb5 Mon Sep 17 00:00:00 2001 From: Lakshmi Ramasubramanian Date: Wed, 11 Dec 2019 08:47:04 -0800 Subject: IMA: Define an IMA hook to measure keys Measure asymmetric keys used for verifying file signatures, certificates, etc. This patch defines a new IMA hook namely ima_post_key_create_or_update() to measure the payload used to create a new asymmetric key or update an existing asymmetric key. Asymmetric key structure is defined only when CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE is defined. Since the IMA hook measures asymmetric keys, the IMA hook is defined in a new file namely ima_asymmetric_keys.c which is built only if CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE is defined. Signed-off-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar --- security/integrity/ima/Makefile | 1 + security/integrity/ima/ima_asymmetric_keys.c | 52 ++++++++++++++++++++++++++++ 2 files changed, 53 insertions(+) create mode 100644 security/integrity/ima/ima_asymmetric_keys.c (limited to 'security') diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile index 31d57cdf2421..207a0a9eb72c 100644 --- a/security/integrity/ima/Makefile +++ b/security/integrity/ima/Makefile @@ -12,3 +12,4 @@ ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o +obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += ima_asymmetric_keys.o diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c new file mode 100644 index 000000000000..994d89d58af9 --- /dev/null +++ b/security/integrity/ima/ima_asymmetric_keys.c @@ -0,0 +1,52 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2019 Microsoft Corporation + * + * Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com) + * + * File: ima_asymmetric_keys.c + * Defines an IMA hook to measure asymmetric keys on key + * create or update. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include "ima.h" + +/** + * ima_post_key_create_or_update - measure asymmetric keys + * @keyring: keyring to which the key is linked to + * @key: created or updated key + * @payload: The data used to instantiate or update the key. + * @payload_len: The length of @payload. + * @flags: key flags + * @create: flag indicating whether the key was created or updated + * + * Keys can only be measured, not appraised. + * The payload data used to instantiate or update the key is measured. + */ +void ima_post_key_create_or_update(struct key *keyring, struct key *key, + const void *payload, size_t payload_len, + unsigned long flags, bool create) +{ + /* Only asymmetric keys are handled by this hook. */ + if (key->type != &key_type_asymmetric) + return; + + if (!payload || (payload_len == 0)) + return; + + /* + * keyring->description points to the name of the keyring + * (such as ".builtin_trusted_keys", ".ima", etc.) to + * which the given key is linked to. + * + * The name of the keyring is passed in the "eventname" + * parameter to process_buffer_measurement() and is set + * in the "eventname" field in ima_event_data for + * the key measurement IMA event. + */ + process_buffer_measurement(payload, payload_len, + keyring->description, KEY_CHECK, 0); +} -- cgit v1.2.3