From patchwork Thu Oct 5 18:25:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 13410601 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D203E92727 for ; Thu, 5 Oct 2023 18:26:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231182AbjJES0P (ORCPT ); Thu, 5 Oct 2023 14:26:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230520AbjJES0O (ORCPT ); Thu, 5 Oct 2023 14:26:14 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6E0079F for ; Thu, 5 Oct 2023 11:26:13 -0700 (PDT) Received: from tushar-HP-Pavilion-Laptop-15-eg0xxx.lan (unknown [50.46.228.62]) by linux.microsoft.com (Postfix) with ESMTPSA id 40C5D20B74C3; Thu, 5 Oct 2023 11:26:12 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 40C5D20B74C3 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1696530372; bh=jTgIKen7lOsEgySVaootVrx/1KoXxKlHIzYHAp+LQX8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IKHGNshri6kq4ulxSHipZH9PjQLTb2G0gVRuVEgo13Amyndbvug3oV9DlxA7IuV36 Sgqvq7nl/l6i9WtZfRCS3zH6JvwkkT9sCdDv2AK46gxEGkVc1RVT7XGzv1Tw2m79Wf LzF+CQFcB4Z/syEzcGfaC62Sn1xBeft+C0kZ0+b8= From: Tushar Sugandhi To: zohar@linux.ibm.com, ebiederm@xmission.com, noodles@fb.com, bauermann@kolabnow.com, kexec@lists.infradead.org, linux-integrity@vger.kernel.org Cc: code@tyhicks.com, nramas@linux.microsoft.com, paul@paul-moore.com Subject: [PATCH v2 2/7] ima: move ima_dump_measurement_list call from kexec load to execute Date: Thu, 5 Oct 2023 11:25:57 -0700 Message-Id: <20231005182602.634615-3-tusharsu@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20231005182602.634615-1-tusharsu@linux.microsoft.com> References: <20231005182602.634615-1-tusharsu@linux.microsoft.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org In the current IMA implementation, ima_dump_measurement_list() is called during the kexec 'load' operation. This can result in loss of IMA measurements taken between the 'load' and 'execute' phases when the system goes through Kexec soft reboot to a new Kernel. The call to the function ima_dump_measurement_list() needs to be moved out of the function ima_add_kexec_buffer() and needs to be called during the kexec 'execute' operation. Implement a function ima_update_kexec_buffer() that is called during kexec 'execute', allowing IMA to update the measurement list with the events between kexec 'load' and 'execute'. Move the ima_dump_measurement_list() call from ima_add_kexec_buffer() to ima_update_kexec_buffer(). Make ima_kexec_buffer and kexec_segment_size variables global, so that they can be accessed during both kexec 'load' and 'execute'. Add functions ima_measurements_suspend() and ima_measurements_resume() to set and reset the 'suspend_ima_measurements' variable respectively, to suspend/resume IMA measurements. Use the existing 'ima_extend_list_mutex' to ensure that the operations are thread-safe. These function calls will help maintaining the integrity of the IMA log while it is being copied to the new Kernel's buffer. Add a reboot notifier_block 'update_buffer_nb' to ensure the function ima_update_kexec_buffer() gets called during kexec soft-reboot. Signed-off-by: Tushar Sugandhi --- security/integrity/ima/ima.h | 2 ++ security/integrity/ima/ima_kexec.c | 58 +++++++++++++++++++++++++----- security/integrity/ima/ima_queue.c | 18 ++++++++++ 3 files changed, 69 insertions(+), 9 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index c29db699c996..49a6047dd8eb 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -161,6 +161,8 @@ bool ima_template_has_modsig(const struct ima_template_desc *ima_template); int ima_restore_measurement_entry(struct ima_template_entry *entry); int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_measurements_show(struct seq_file *m, void *v); +void ima_measurements_suspend(void); +void ima_measurements_resume(void); unsigned long ima_get_binary_runtime_size(void); int ima_init_template(void); void ima_init_template_list(void); diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index 307e07991865..2c11bbe6efef 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -17,6 +17,8 @@ #ifdef CONFIG_IMA_KEXEC struct seq_file ima_kexec_file; struct ima_kexec_hdr ima_khdr; +static void *ima_kexec_buffer; +static size_t kexec_segment_size; void ima_clear_kexec_file(void) { @@ -142,7 +144,6 @@ void ima_add_kexec_buffer(struct kimage *image) /* use more understandable variable names than defined in kbuf */ void *kexec_buffer = NULL; size_t kexec_buffer_size; - size_t kexec_segment_size; int ret; /* @@ -167,14 +168,6 @@ void ima_add_kexec_buffer(struct kimage *image) return; } - ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, - kexec_segment_size); - if (ret < 0) { - pr_err("%s: Failed to dump IMA measurements. Error:%d.\n", - __func__, ret); - return; - } - kbuf.buffer = kexec_buffer; kbuf.bufsz = kexec_buffer_size; kbuf.memsz = kexec_segment_size; @@ -192,6 +185,53 @@ void ima_add_kexec_buffer(struct kimage *image) pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n", kbuf.mem); } + +/* + * Called during kexec execute so that IMA can update the measurement list. + */ +static int ima_update_kexec_buffer(struct notifier_block *self, + unsigned long action, void *data) +{ + void *buf = NULL; + size_t buf_size; + bool resume = false; + int ret; + + if (!kexec_in_progress) { + pr_info("%s: No kexec in progress.\n", __func__); + return NOTIFY_OK; + } + + if (!ima_kexec_buffer) { + pr_err("%s: Kexec buffer not set.\n", __func__); + return NOTIFY_OK; + } + + ima_measurements_suspend(); + + buf_size = ima_get_binary_runtime_size(); + ret = ima_dump_measurement_list(&buf_size, &buf, + kexec_segment_size); + + if (!buf || ret < 0) { + pr_err("%s: Dump measurements failed. Error:%d\n", + __func__, ret); + resume = true; + goto out; + } + memcpy(ima_kexec_buffer, buf, buf_size); +out: + ima_kexec_buffer = NULL; + + if (resume) + ima_measurements_resume(); + + return NOTIFY_OK; +} +struct notifier_block update_buffer_nb = { + .notifier_call = ima_update_kexec_buffer, +}; + #endif /* IMA_KEXEC */ /* diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c index 532da87ce519..9e7d1196006e 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -44,6 +44,11 @@ struct ima_h_table ima_htable = { */ static DEFINE_MUTEX(ima_extend_list_mutex); +/* + * Used internally by the kernel to suspend-resume ima measurements. + */ +static atomic_t suspend_ima_measurements; + /* lookup up the digest value in the hash table, and return the entry */ static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value, int pcr) @@ -147,6 +152,19 @@ static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr) pr_err("Error Communicating to TPM chip, result: %d\n", result); return result; } +void ima_measurements_suspend(void) +{ + mutex_lock(&ima_extend_list_mutex); + atomic_set(&suspend_ima_measurements, 1); + mutex_unlock(&ima_extend_list_mutex); +} + +void ima_measurements_resume(void) +{ + mutex_lock(&ima_extend_list_mutex); + atomic_set(&suspend_ima_measurements, 0); + mutex_unlock(&ima_extend_list_mutex); +} /* * Add template entry to the measurement list and hash table, and