From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-25.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2365FC433E6 for ; Tue, 5 Jan 2021 18:54:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D700C22D72 for ; Tue, 5 Jan 2021 18:54:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729619AbhAESxr (ORCPT ); Tue, 5 Jan 2021 13:53:47 -0500 Received: from linux.microsoft.com ([13.77.154.182]:34276 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726258AbhAESxr (ORCPT ); Tue, 5 Jan 2021 13:53:47 -0500 Received: from [192.168.86.31] (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id 167CF20B7192; Tue, 5 Jan 2021 10:53:05 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 167CF20B7192 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1609872786; bh=4z0o1Q8ayYYboZSCQkOiVolnujOFfwOB2QkQyjTsAWE=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=jZyYAnaB9eK3CuK0Ewu7CmvJoRWBLCBCMZWVFAzdfUA2jknYGnBTUMcEZklImzaYz l1KgcpBPp67qtRox4suu7A0AFaAxfNKjFG6Qk1cfEiIE17LRYX0hhC3w3JGzawYLEC 5emVQZXR+1yklfN/Hsj8IbUAfgfE8v8ct+iBxJaY= Subject: Re: [PATCH v9 2/8] IMA: add support to measure buffer data hash To: Mimi Zohar , stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.com, paul@paul-moore.com Cc: tyhicks@linux.microsoft.com, sashal@kernel.org, jmorris@namei.org, nramas@linux.microsoft.com, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com References: <20201212180251.9943-1-tusharsu@linux.microsoft.com> <20201212180251.9943-3-tusharsu@linux.microsoft.com> <4e83480731b937cea479f688029560444b9cb66a.camel@linux.ibm.com> From: Tushar Sugandhi Message-ID: <3fdb72ae-f291-386b-e7b9-688dfe092dc5@linux.microsoft.com> Date: Tue, 5 Jan 2021 10:53:04 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <4e83480731b937cea479f688029560444b9cb66a.camel@linux.ibm.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On 2020-12-23 4:03 p.m., Mimi Zohar wrote: > On Sat, 2020-12-12 at 10:02 -0800, Tushar Sugandhi wrote: >> The original IMA buffer data measurement sizes were small (e.g. boot >> command line), but the new buffer data measurement use cases have data >> sizes that are a lot larger. Just as IMA measures the file data hash, >> not the file data, IMA should similarly support the option for measuring >> the hash of the buffer data. >> >> Measuring in-memory buffer-data/buffer-data-hash is different than >> measuring file-data/file-data-hash. For the file, IMA stores the >> measurements in both measurement log and the file's extended attribute - >> which can later be used for appraisal as well. For buffer, the >> measurements are only stored in the IMA log, since the buffer has no >> extended attributes associated with it. > > By definition, buffer data is only measured. Nothing new is added by > the above paragraph. Please remove it. > Sure. Will remove. >> >> Introduce a boolean parameter measure_buf_hash to support measuring >> hash of a buffer, which would be much smaller, instead of the buffer >> itself. > > Like the patch Subject line use "the buffer data hash" instead of the > "hash of a buffer". > Will do. > There's no need to include the boolean parameter name > "measure_buf_hash". Please remove it. > Will do. >> >> Signed-off-by: Tushar Sugandhi >> Reviewed-by: Tyler Hicks >> --- >> security/integrity/ima/ima.h | 3 +- >> security/integrity/ima/ima_appraise.c | 2 +- >> security/integrity/ima/ima_asymmetric_keys.c | 2 +- >> security/integrity/ima/ima_main.c | 38 +++++++++++++++++--- >> security/integrity/ima/ima_queue_keys.c | 3 +- >> 5 files changed, 39 insertions(+), 9 deletions(-) >> >> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h >> index e5622ce8cbb1..fa3044a7539f 100644 >> --- a/security/integrity/ima/ima.h >> +++ b/security/integrity/ima/ima.h >> @@ -268,7 +268,8 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file, >> struct ima_template_desc *template_desc); >> void process_buffer_measurement(struct inode *inode, const void *buf, int size, >> const char *eventname, enum ima_hooks func, >> - int pcr, const char *func_data); >> + int pcr, const char *func_data, >> + bool measure_buf_hash); > > Please abbreviate the boolean name to "hash". The test would then be > "if (hash == true)" or "if (hash)". > Will do. >> void ima_audit_measurement(struct integrity_iint_cache *iint, >> const unsigned char *filename); >> int ima_alloc_init_template(struct ima_event_data *event_data, >> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c >> index 8361941ee0a1..46ffa38bab12 100644 >> --- a/security/integrity/ima/ima_appraise.c >> +++ b/security/integrity/ima/ima_appraise.c >> @@ -352,7 +352,7 @@ int ima_check_blacklist(struct integrity_iint_cache *iint, >> if ((rc == -EPERM) && (iint->flags & IMA_MEASURE)) >> process_buffer_measurement(NULL, digest, digestsize, >> "blacklisted-hash", NONE, >> - pcr, NULL); >> + pcr, NULL, false); >> } >> >> return rc; >> diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c >> index 1c68c500c26f..a74095793936 100644 >> --- a/security/integrity/ima/ima_asymmetric_keys.c >> +++ b/security/integrity/ima/ima_asymmetric_keys.c >> @@ -60,5 +60,5 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key, >> */ >> process_buffer_measurement(NULL, payload, payload_len, >> keyring->description, KEY_CHECK, 0, >> - keyring->description); >> + keyring->description, false); >> } >> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c >> index e76ef4bfd0f4..0f8409d77602 100644 >> --- a/security/integrity/ima/ima_main.c >> +++ b/security/integrity/ima/ima_main.c >> @@ -779,7 +779,7 @@ int ima_post_load_data(char *buf, loff_t size, >> } >> >> /* >> - * process_buffer_measurement - Measure the buffer to ima log. >> + * process_buffer_measurement - Measure the buffer or the buffer data hash >> * @inode: inode associated with the object being measured (NULL for KEY_CHECK) >> * @buf: pointer to the buffer that needs to be added to the log. >> * @size: size of buffer(in bytes). >> @@ -787,12 +787,23 @@ int ima_post_load_data(char *buf, loff_t size, >> * @func: IMA hook >> * @pcr: pcr to extend the measurement >> * @func_data: private data specific to @func, can be NULL. >> + * @measure_buf_hash: measure buffer hash > > ^@hash: measure buffer data hash > Agreed. Will fix. >> * >> - * Based on policy, the buffer is measured into the ima log. >> + * Measure the buffer into the IMA log, and extend the @pcr. > > IMA always measures/appraises files and measures buffer data based on > policy. The above sentence succintly summarizes what > process_buffer_measurement() does. This patch adds support for > measuring the "buffer data hash". The following would be an > appropriate change. > > * Based on policy, either the buffer data or buffer data hash is > measured > Sounds good. Will update. >> + * >> + * Determine what buffers are allowed to be measured, based on the policy rules >> + * and the IMA hook passed using @func. >> + * >> + * Use @func_data, if provided, to match against the measurement policy rule >> + * data for @func. >> + * >> + * If @measure_buf_hash is set to true - measure hash of the buffer data, >> + * else measure the buffer data itself. > > This patch should be limited to adding "buffer data hash" support. > These changes don't belong in this patch. Please remove. > Agreed. Will remove. >> */ >> void process_buffer_measurement(struct inode *inode, const void *buf, int size, >> const char *eventname, enum ima_hooks func, >> - int pcr, const char *func_data) >> + int pcr, const char *func_data, >> + bool measure_buf_hash) >> { >> int ret = 0; >> const char *audit_cause = "ENOMEM"; >> @@ -807,6 +818,8 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size, >> struct ima_digest_data hdr; >> char digest[IMA_MAX_DIGEST_SIZE]; >> } hash = {}; >> + char buf_hash[IMA_MAX_DIGEST_SIZE]; >> + int buf_hash_len = hash_digest_size[ima_hash_algo]; >> int violation = 0; >> int action = 0; >> u32 secid; >> @@ -849,13 +862,27 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size, >> goto out; >> } >> >> + if (measure_buf_hash) { > > ^ if (hash) { Yes. >> + memcpy(buf_hash, hash.hdr.digest, buf_hash_len); >> + >> + ret = ima_calc_buffer_hash(buf_hash, buf_hash_len, >> + iint.ima_hash); >> + if (ret < 0) { >> + audit_cause = "measure_buf_hash_error"; > > I don't see a good no reason for defining a new audit cause. Use the > existing "hashing_error". > > thanks, > > Mimi > Thanks, Tushar >> + goto out; >> + } >> + >> + event_data.buf = buf_hash; >> + event_data.buf_len = buf_hash_len; >> + } >> + >> ret = ima_alloc_init_template(&event_data, &entry, template); >> if (ret < 0) { >> audit_cause = "alloc_entry"; >> goto out; >> } >> >> - ret = ima_store_template(entry, violation, NULL, buf, pcr); >> + ret = ima_store_template(entry, violation, NULL, event_data.buf, pcr); >> if (ret < 0) { >> audit_cause = "store_entry"; >> ima_free_template_entry(entry); >> @@ -890,7 +917,8 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) >> return; >> >> process_buffer_measurement(file_inode(f.file), buf, size, >> - "kexec-cmdline", KEXEC_CMDLINE, 0, NULL); >> + "kexec-cmdline", KEXEC_CMDLINE, 0, NULL, >> + false); >> fdput(f); >> } >> >> diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c >> index 69a8626a35c0..c2f2ad34f9b7 100644 >> --- a/security/integrity/ima/ima_queue_keys.c >> +++ b/security/integrity/ima/ima_queue_keys.c >> @@ -162,7 +162,8 @@ void ima_process_queued_keys(void) >> entry->payload_len, >> entry->keyring_name, >> KEY_CHECK, 0, >> - entry->keyring_name); >> + entry->keyring_name, >> + false); >> list_del(&entry->list); >> ima_free_key_entry(entry); >> } >