From patchwork Wed Sep 23 19:20:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11795545 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BAF95112E for ; Wed, 23 Sep 2020 19:20:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FFFD21D92 for ; Wed, 23 Sep 2020 19:20:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="rfBgp964" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726780AbgIWTU2 (ORCPT ); Wed, 23 Sep 2020 15:20:28 -0400 Received: from linux.microsoft.com ([13.77.154.182]:47356 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726638AbgIWTUW (ORCPT ); Wed, 23 Sep 2020 15:20:22 -0400 Received: from tusharsu-Ubuntu.lan (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id 4447C2089E54; Wed, 23 Sep 2020 12:20:19 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 4447C2089E54 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1600888819; bh=SOTaZce6/RdN7od+EbMFXj1LgFxOXmnEyQ3AaS1qrxU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rfBgp9640BotbUFbtAcr2pea/uKjcZ5sSvft2z+zVclFD7THE82dXzLTQT/uS7knV kU4peJ4JktGLrDNKYL1DYcvsTzhj9fQ2NfykT6tOWtDhFiN0DL7gF59qC51ZQIXBYK QA/c+wgcDlv28dTp02FpRb6UZA6Yogj0ungUonAE= From: Tushar Sugandhi To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.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 Subject: [PATCH v4 1/6] IMA: generalize keyring specific measurement constructs Date: Wed, 23 Sep 2020 12:20:06 -0700 Message-Id: <20200923192011.5293-2-tusharsu@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923192011.5293-1-tusharsu@linux.microsoft.com> References: <20200923192011.5293-1-tusharsu@linux.microsoft.com> Precedence: bulk List-ID: IMA functions such as ima_match_keyring(), process_buffer_measurement(), ima_match_policy() etc. handle data specific to keyrings. Currently, these constructs are not generic to handle any func specific data. This makes it harder to extend without code duplication. Refactor the keyring specific measurement constructs to be generic and reusable in other measurement scenarios. Signed-off-by: Tushar Sugandhi --- security/integrity/ima/ima.h | 6 ++--- security/integrity/ima/ima_api.c | 6 ++--- security/integrity/ima/ima_main.c | 6 ++--- security/integrity/ima/ima_policy.c | 38 ++++++++++++++++------------- 4 files changed, 30 insertions(+), 26 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 38043074ce5e..8875085db689 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -255,7 +255,7 @@ static inline void ima_process_queued_keys(void) {} int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid, int mask, enum ima_hooks func, int *pcr, struct ima_template_desc **template_desc, - const char *keyring); + const char *func_data); int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func); int ima_collect_measurement(struct integrity_iint_cache *iint, struct file *file, void *buf, loff_t size, @@ -267,7 +267,7 @@ 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 *keyring); + int pcr, const char *func_data); void ima_audit_measurement(struct integrity_iint_cache *iint, const unsigned char *filename); int ima_alloc_init_template(struct ima_event_data *event_data, @@ -283,7 +283,7 @@ const char *ima_d_path(const struct path *path, char **pathbuf, char *filename); int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid, enum ima_hooks func, int mask, int flags, int *pcr, struct ima_template_desc **template_desc, - const char *keyring); + const char *func_data); void ima_init_policy(void); void ima_update_policy(void); void ima_update_policy_flag(void); diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index 4f39fb93f278..af218babd198 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -170,7 +170,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename, * @func: caller identifier * @pcr: pointer filled in if matched measure policy sets pcr= * @template_desc: pointer filled in if matched measure policy sets template= - * @keyring: keyring name used to determine the action + * @func_data: private data specific to @func, can be NULL. * * The policy is defined in terms of keypairs: * subj=, obj=, type=, func=, mask=, fsmagic= @@ -186,14 +186,14 @@ void ima_add_violation(struct file *file, const unsigned char *filename, int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid, int mask, enum ima_hooks func, int *pcr, struct ima_template_desc **template_desc, - const char *keyring) + const char *func_data) { int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE | IMA_HASH; flags &= ima_policy_flag; return ima_match_policy(inode, cred, secid, func, mask, flags, pcr, - template_desc, keyring); + template_desc, func_data); } /* diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 8a91711ca79b..c870fd6d2f83 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -732,13 +732,13 @@ int ima_load_data(enum kernel_load_data_id id) * @eventname: event name to be used for the buffer entry. * @func: IMA hook * @pcr: pcr to extend the measurement - * @keyring: keyring name to determine the action to be performed + * @func_data: private data specific to @func, can be NULL. * * Based on policy, the buffer is measured into the ima log. */ void process_buffer_measurement(struct inode *inode, const void *buf, int size, const char *eventname, enum ima_hooks func, - int pcr, const char *keyring) + int pcr, const char *func_data) { int ret = 0; const char *audit_cause = "ENOMEM"; @@ -770,7 +770,7 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size, if (func) { security_task_getsecid(current, &secid); action = ima_get_action(inode, current_cred(), secid, 0, func, - &pcr, &template, keyring); + &pcr, &template, func_data); if (!(action & IMA_MEASURE)) return; } diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index fe1df373c113..31a772d8a86b 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -451,15 +451,19 @@ int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event, } /** - * ima_match_keyring - determine whether the keyring matches the measure rule - * @rule: a pointer to a rule - * @keyring: name of the keyring to match against the measure rule + * ima_match_rule_data - determine whether the given func_data matches + * the measure rule data + * @rule: IMA policy rule + * @opt_list: rule data to match func_data against + * @func_data: data to match against the measure rule data * @cred: a pointer to a credentials structure for user validation * - * Returns true if keyring matches one in the rule, false otherwise. + * Returns true if func_data matches one in the rule, false otherwise. */ -static bool ima_match_keyring(struct ima_rule_entry *rule, - const char *keyring, const struct cred *cred) +static bool ima_match_rule_data(struct ima_rule_entry *rule, + const struct ima_rule_opt_list *opt_list, + const char *func_data, + const struct cred *cred) { bool matched = false; size_t i; @@ -467,14 +471,14 @@ static bool ima_match_keyring(struct ima_rule_entry *rule, if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid)) return false; - if (!rule->keyrings) + if (!opt_list) return true; - if (!keyring) + if (!func_data) return false; - for (i = 0; i < rule->keyrings->count; i++) { - if (!strcmp(rule->keyrings->items[i], keyring)) { + for (i = 0; i < opt_list->count; i++) { + if (!strcmp(opt_list->items[i], func_data)) { matched = true; break; } @@ -491,20 +495,21 @@ static bool ima_match_keyring(struct ima_rule_entry *rule, * @secid: the secid of the task to be validated * @func: LIM hook identifier * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC) - * @keyring: keyring name to check in policy for KEY_CHECK func + * @func_data: private data specific to @func, can be NULL. * * Returns true on rule match, false on failure. */ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, const struct cred *cred, u32 secid, enum ima_hooks func, int mask, - const char *keyring) + const char *func_data) { int i; if (func == KEY_CHECK) { return (rule->flags & IMA_FUNC) && (rule->func == func) && - ima_match_keyring(rule, keyring, cred); + ima_match_rule_data(rule, rule->keyrings, func_data, + cred); } if ((rule->flags & IMA_FUNC) && (rule->func != func && func != POST_SETATTR)) @@ -608,8 +613,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func) * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC) * @pcr: set the pcr to extend * @template_desc: the template that should be used for this rule - * @keyring: the keyring name, if given, to be used to check in the policy. - * keyring can be NULL if func is anything other than KEY_CHECK. + * @func_data: private data specific to @func, can be NULL. * * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type) * conditions. @@ -621,7 +625,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func) int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid, enum ima_hooks func, int mask, int flags, int *pcr, struct ima_template_desc **template_desc, - const char *keyring) + const char *func_data) { struct ima_rule_entry *entry; int action = 0, actmask = flags | (flags << 1); @@ -636,7 +640,7 @@ int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid, continue; if (!ima_match_rules(entry, inode, cred, secid, func, mask, - keyring)) + func_data)) continue; action |= entry->flags & IMA_ACTION_FLAGS; From patchwork Wed Sep 23 19:20:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11795537 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2E8B9112E for ; Wed, 23 Sep 2020 19:20:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 09FF520BED for ; Wed, 23 Sep 2020 19:20:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="m7RL+cJJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726760AbgIWTUV (ORCPT ); Wed, 23 Sep 2020 15:20:21 -0400 Received: from linux.microsoft.com ([13.77.154.182]:47374 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726498AbgIWTUU (ORCPT ); Wed, 23 Sep 2020 15:20:20 -0400 Received: from tusharsu-Ubuntu.lan (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id BF3E420B36E7; Wed, 23 Sep 2020 12:20:19 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com BF3E420B36E7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1600888820; bh=msIiW4AnSlFN198DxHsM0/k20Lg9ddIuwcYdunV1Csc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m7RL+cJJpxVV/AF4UUNJvcJiibwinq+e4AdIbro/l70SzJ8ilEVriJlWR++7+6Dtr qagJZPU4s+bB8ndhibWdoJwooDaIRdh4+tM+dsymPoWroOA3XcVhOAjScdGjxpXMAN P/TKZdqRZ46Lb04mkQbRKAzBspH94cABUafIGPWc= From: Tushar Sugandhi To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.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 Subject: [PATCH v4 2/6] IMA: conditionally allow empty rule data Date: Wed, 23 Sep 2020 12:20:07 -0700 Message-Id: <20200923192011.5293-3-tusharsu@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923192011.5293-1-tusharsu@linux.microsoft.com> References: <20200923192011.5293-1-tusharsu@linux.microsoft.com> Precedence: bulk List-ID: ima_match_rule_data() permits the func to pass empty func_data. For instance, for the following func, the func_data keyrings= is optional. measure func=KEY_CHECK keyrings=.ima But a new func in future may want to constrain the func_data to be non-empty. ima_match_rule_data() should support this constraint and it shouldn't be hard-coded in ima_match_rule_data(). Update ima_match_rule_data() to conditionally allow empty func_data for the func that needs it. Signed-off-by: Tushar Sugandhi --- security/integrity/ima/ima_policy.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 31a772d8a86b..8866e84d0062 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -456,6 +456,7 @@ int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event, * @rule: IMA policy rule * @opt_list: rule data to match func_data against * @func_data: data to match against the measure rule data + * @allow_empty_opt_list: If true matches all func_data * @cred: a pointer to a credentials structure for user validation * * Returns true if func_data matches one in the rule, false otherwise. @@ -463,6 +464,7 @@ int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event, static bool ima_match_rule_data(struct ima_rule_entry *rule, const struct ima_rule_opt_list *opt_list, const char *func_data, + bool allow_empty_opt_list, const struct cred *cred) { bool matched = false; @@ -472,7 +474,7 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule, return false; if (!opt_list) - return true; + return allow_empty_opt_list; if (!func_data) return false; @@ -509,7 +511,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, if (func == KEY_CHECK) { return (rule->flags & IMA_FUNC) && (rule->func == func) && ima_match_rule_data(rule, rule->keyrings, func_data, - cred); + true, cred); } if ((rule->flags & IMA_FUNC) && (rule->func != func && func != POST_SETATTR)) From patchwork Wed Sep 23 19:20:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11795575 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D5A63112E for ; Wed, 23 Sep 2020 19:20:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE047221EF for ; Wed, 23 Sep 2020 19:20:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="oaU1G+GL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726711AbgIWTUn (ORCPT ); Wed, 23 Sep 2020 15:20:43 -0400 Received: from linux.microsoft.com ([13.77.154.182]:47388 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726613AbgIWTUW (ORCPT ); Wed, 23 Sep 2020 15:20:22 -0400 Received: from tusharsu-Ubuntu.lan (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id 450352089E57; Wed, 23 Sep 2020 12:20:20 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 450352089E57 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1600888820; bh=pcLyMA0uNkykd7e9lq2gKboYQH9AWY9Kdkta8tpqSsw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oaU1G+GL318AUbfV78EANkWork+aJE4AVqJfgsfPA3yWu/1Mh3HIzMJ4PpkXXFBb0 x7B3wZD/g22immRpaIe9Tab93VohJy3idzPfNjeCyf0kOEzuZOGzzzEIjafVp2w7Hu Lr0jpcN1n8mURwrDPh6fyILxUK3T6U4IBVkrobCI= From: Tushar Sugandhi To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.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 Subject: [PATCH v4 3/6] IMA: update process_buffer_measurement to measure buffer hash Date: Wed, 23 Sep 2020 12:20:08 -0700 Message-Id: <20200923192011.5293-4-tusharsu@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923192011.5293-1-tusharsu@linux.microsoft.com> References: <20200923192011.5293-1-tusharsu@linux.microsoft.com> MIME-Version: 1.0 Precedence: bulk List-ID: process_buffer_measurement() currently only measures the input buffer. In case of SeLinux policy measurement, the policy being measured could be large (several MB). This may result in a large entry in IMA measurement log. Introduce a boolean parameter measure_buf_hash to support measuring hash of a buffer, which would be much smaller, instead of the buffer itself. To use the functionality introduced in this patch, the attestation client and the server changes need to go hand in hand. The client/kernel would know what data is being measured as-is (e.g. KEXEC_CMDLINE), and what data has it’s hash measured (e.g. SeLinux Policy). And the attestation server should verify data/hash accordingly. Just like the data being measured in other cases, the attestation server will know what are possible values of the large buffers being measured. e.g. the possible valid SeLinux policy values that are being pushed to the client. The attestation server will have to maintain the hash of those buffer values. Signed-off-by: Tushar Sugandhi --- 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 | 25 ++++++++++++++++++-- security/integrity/ima/ima_queue_keys.c | 3 ++- 5 files changed, 29 insertions(+), 6 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 8875085db689..0f77e0b697a3 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -267,7 +267,8 @@ 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); 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 372d16382960..20adffe5bf58 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -336,7 +336,7 @@ 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 c870fd6d2f83..6888fc372abf 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -733,12 +733,15 @@ int ima_load_data(enum kernel_load_data_id id) * @func: IMA hook * @pcr: pcr to extend the measurement * @func_data: private data specific to @func, can be NULL. + * @measure_buf_hash: if set to true - will measure hash of the buf, + * instead of buf * * Based on policy, the buffer is measured into the ima log. */ 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"; @@ -753,6 +756,8 @@ 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 digest_hash[IMA_MAX_DIGEST_SIZE]; + int hash_len = hash_digest_size[ima_hash_algo]; int violation = 0; int action = 0; u32 secid; @@ -801,6 +806,21 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size, goto out; } + if (measure_buf_hash) { + memcpy(digest_hash, hash.hdr.digest, hash_len); + + ret = ima_calc_buffer_hash(digest_hash, + hash_len, + iint.ima_hash); + if (ret < 0) { + audit_cause = "measure_buf_hash_error"; + goto out; + } + + event_data.buf = digest_hash; + event_data.buf_len = hash_len; + } + ret = ima_alloc_init_template(&event_data, &entry, template); if (ret < 0) { audit_cause = "alloc_entry"; @@ -842,7 +862,8 @@ 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); } From patchwork Wed Sep 23 19:20:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11795555 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 02BCC112C for ; Wed, 23 Sep 2020 19:20:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D6A5920BED for ; Wed, 23 Sep 2020 19:20:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="Nftv16el" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726806AbgIWTU3 (ORCPT ); Wed, 23 Sep 2020 15:20:29 -0400 Received: from linux.microsoft.com ([13.77.154.182]:47400 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726761AbgIWTUW (ORCPT ); Wed, 23 Sep 2020 15:20:22 -0400 Received: from tusharsu-Ubuntu.lan (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id C73252089E58; Wed, 23 Sep 2020 12:20:20 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com C73252089E58 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1600888821; bh=2FNwvx49AfXNiGqLOUX6pzzqyCNzi5u8FEaXRE5OT/I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Nftv16elAWhpMY6rI6VQCO/6/lsNQgClY9rx60Pn7tpmtcxVxngLn6Yws1M9ZxScT dGuqErmY5EZ07/+iIBLfA5tvb6d/mC1wDB4pUEavUzWQYg5fNFx/qGZSKltG8JNLkC qX6hHKKDXeyO6dhNWrR26dFzMJsq28P0EsQZhvCA= From: Tushar Sugandhi To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.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 Subject: [PATCH v4 4/6] IMA: add policy to measure critical data from kernel components Date: Wed, 23 Sep 2020 12:20:09 -0700 Message-Id: <20200923192011.5293-5-tusharsu@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923192011.5293-1-tusharsu@linux.microsoft.com> References: <20200923192011.5293-1-tusharsu@linux.microsoft.com> Precedence: bulk List-ID: There would be several candidate kernel components suitable for IMA measurement. Not all of them would have support for IMA measurement. Also, system administrators may not want to measure data for all of them, even when they support IMA measurement. An IMA policy option specific to various kernel components is needed to measure their respective critical data. This policy option needs to be constrained to measure data for specific kernel components that are specified as input values to the policy option. Add a new IMA policy option - "data_sources:=" to allow measuring various critical kernel components. This policy option would enable the system administrators to limit the measurement to the components listed in "data_sources:=", if the components support IMA measurement. The new policy option "data_sources:=" is different from the existing policy option "keyrings:=". In case of "keyrings:=", a policy may measure all keyrings (when "keyrings:=" option is not provided for func KEY_CHECK), or may constrain which keyrings need to be measured (when "keyrings:=" option is provided for func KEY_CHECK). But unlike "keyrings:=", the entries in "data_sources:=" would have different data format. Further, the components listed in "data_sources:=" need to be modified to call IMA to measure their data. Therefore, unlike "keyrings:=", IMA shouldn't measure all of the components by default, when "data_sources:=" is not specified. Because measuring non-vetted components just by specifying them as a policy option value may impact the overall reliability of the system. To address this, "data_sources:=" should be a mandatory policy option for func=CRITICAL_DATA. This func is introduced in the 5th patch in this series). And the compile-time vetting functionality described above is introduced in the 6th patch in this series. Signed-off-by: Tushar Sugandhi --- Documentation/ABI/testing/ima_policy | 3 +++ security/integrity/ima/ima_policy.c | 29 +++++++++++++++++++++++++++- 2 files changed, 31 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index cd572912c593..a81cf79fb255 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -48,6 +48,9 @@ Description: template:= name of a defined IMA template type (eg, ima-ng). Only valid when action is "measure". pcr:= decimal value + data_sources:= list of kernel components + (eg, selinux|apparmor|dm-crypt) that contain data critical + to the security of the kernel. default policy: # PROC_SUPER_MAGIC diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 8866e84d0062..89452245f54a 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -33,6 +33,7 @@ #define IMA_PCR 0x0100 #define IMA_FSNAME 0x0200 #define IMA_KEYRINGS 0x0400 +#define IMA_DATA_SOURCES 0x0800 #define UNKNOWN 0 #define MEASURE 0x0001 /* same as IMA_MEASURE */ @@ -84,6 +85,7 @@ struct ima_rule_entry { } lsm[MAX_LSM_RULES]; char *fsname; struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */ + struct ima_rule_opt_list *data_sources; /* Measure data from these sources */ struct ima_template_desc *template; }; @@ -911,7 +913,7 @@ enum { Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt, Opt_appraise_type, Opt_appraise_flag, Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings, - Opt_err + Opt_data_sources, Opt_err }; static const match_table_t policy_tokens = { @@ -948,6 +950,7 @@ static const match_table_t policy_tokens = { {Opt_pcr, "pcr=%s"}, {Opt_template, "template=%s"}, {Opt_keyrings, "keyrings=%s"}, + {Opt_data_sources, "data_sources=%s"}, {Opt_err, NULL} }; @@ -1312,6 +1315,24 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) entry->flags |= IMA_KEYRINGS; break; + case Opt_data_sources: + ima_log_string(ab, "data_sources", + args[0].from); + + if (entry->data_sources) { + result = -EINVAL; + break; + } + + entry->data_sources = ima_alloc_rule_opt_list(args); + if (IS_ERR(entry->data_sources)) { + result = PTR_ERR(entry->data_sources); + entry->data_sources = NULL; + break; + } + + entry->flags |= IMA_DATA_SOURCES; + break; case Opt_fsuuid: ima_log_string(ab, "fsuuid", args[0].from); @@ -1692,6 +1713,12 @@ int ima_policy_show(struct seq_file *m, void *v) seq_puts(m, " "); } + if (entry->flags & IMA_DATA_SOURCES) { + seq_puts(m, "data_sources="); + ima_show_rule_opt_list(m, entry->data_sources); + seq_puts(m, " "); + } + if (entry->flags & IMA_PCR) { snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr); seq_printf(m, pt(Opt_pcr), tbuf); From patchwork Wed Sep 23 19:20:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11795547 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 03A43112C for ; Wed, 23 Sep 2020 19:20:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0FDF21D92 for ; Wed, 23 Sep 2020 19:20:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="jchluQdF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726498AbgIWTU3 (ORCPT ); Wed, 23 Sep 2020 15:20:29 -0400 Received: from linux.microsoft.com ([13.77.154.182]:47420 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726763AbgIWTUX (ORCPT ); Wed, 23 Sep 2020 15:20:23 -0400 Received: from tusharsu-Ubuntu.lan (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id 602502089E59; Wed, 23 Sep 2020 12:20:21 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 602502089E59 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1600888821; bh=CeqH2fYkLev2SJspNAVR1dakUWyzaHtLEkKWdj02GVY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jchluQdFaJAGEDwKfZt61ntxdfJSXObOh535SgxUbztshSKNqeew34hyvMV8qjwLp OJ9lgtx/zOI2sQGzBxW/4wz++B5UZVHTcQAea8dTDwujRdAsbh27WpXdGuS/UO4LwD Zohe/JXbVb5L+mj3rqsC7BDPuL5gQ39Nu1WJWTU8= From: Tushar Sugandhi To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.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 Subject: [PATCH v4 5/6] IMA: add hook to measure critical data from kernel components Date: Wed, 23 Sep 2020 12:20:10 -0700 Message-Id: <20200923192011.5293-6-tusharsu@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923192011.5293-1-tusharsu@linux.microsoft.com> References: <20200923192011.5293-1-tusharsu@linux.microsoft.com> Precedence: bulk List-ID: Currently, IMA does not provide a generic function for kernel components to measure their data. A generic function provided by IMA would enable various parts of the kernel with easier and faster on-boarding to use IMA infrastructure, would avoid code duplication, and consistent usage of IMA policy option "data_sources:=" across the kernel. Add a new IMA func CRITICAL_DATA and a corresponding IMA hook ima_measure_critical_data() to support measuring various critical kernel components. Limit the measurement to the components that are specified in the IMA policy - CRITICAL_DATA+data_sources. Signed-off-by: Tushar Sugandhi --- Documentation/ABI/testing/ima_policy | 8 ++++++- include/linux/ima.h | 8 +++++++ security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_api.c | 2 +- security/integrity/ima/ima_main.c | 26 +++++++++++++++++++++ security/integrity/ima/ima_policy.c | 34 ++++++++++++++++++++++++---- 6 files changed, 72 insertions(+), 7 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index a81cf79fb255..d33bb51309fc 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -29,7 +29,7 @@ Description: base: func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK] [FIRMWARE_CHECK] [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK] - [KEXEC_CMDLINE] [KEY_CHECK] + [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA] mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] [[^]MAY_EXEC] fsmagic:= hex value @@ -51,6 +51,8 @@ Description: data_sources:= list of kernel components (eg, selinux|apparmor|dm-crypt) that contain data critical to the security of the kernel. + Only valid when action is "measure" and func is + CRITICAL_DATA. default policy: # PROC_SUPER_MAGIC @@ -128,3 +130,7 @@ Description: keys added to .builtin_trusted_keys or .ima keyring: measure func=KEY_CHECK keyrings=.builtin_trusted_keys|.ima + + Example of measure rule using CRITICAL_DATA to measure critical data + + measure func=CRITICAL_DATA data_sources=selinux|apparmor|dm-crypt diff --git a/include/linux/ima.h b/include/linux/ima.h index d15100de6cdd..4040f484ac63 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -26,6 +26,10 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size, extern void ima_post_path_mknod(struct dentry *dentry); extern int ima_file_hash(struct file *file, char *buf, size_t buf_size); extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size); +extern void ima_measure_critical_data(const char *event_name, + const char *event_data_source, + const void *buf, int buf_len, + bool measure_buf_hash); #ifdef CONFIG_IMA_KEXEC extern void ima_add_kexec_buffer(struct kimage *image); @@ -104,6 +108,10 @@ static inline int ima_file_hash(struct file *file, char *buf, size_t buf_size) } static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {} +static inline void ima_measure_critical_data(const char *event_name, + const char *event_data_source, + const void *buf, int buf_len, + bool measure_buf_hash) {} #endif /* CONFIG_IMA */ #ifndef CONFIG_IMA_KEXEC diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 0f77e0b697a3..c1acf88e1b5d 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -200,6 +200,7 @@ static inline unsigned int ima_hash_key(u8 *digest) hook(POLICY_CHECK, policy) \ hook(KEXEC_CMDLINE, kexec_cmdline) \ hook(KEY_CHECK, key) \ + hook(CRITICAL_DATA, critical_data) \ hook(MAX_CHECK, none) #define __ima_hook_enumify(ENUM, str) ENUM, diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index af218babd198..9917e1730cb6 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -176,7 +176,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename, * subj=, obj=, type=, func=, mask=, fsmagic= * subj,obj, and type: are LSM specific. * func: FILE_CHECK | BPRM_CHECK | CREDS_CHECK | MMAP_CHECK | MODULE_CHECK - * | KEXEC_CMDLINE | KEY_CHECK + * | KEXEC_CMDLINE | KEY_CHECK | CRITICAL_DATA * mask: contains the permission mask * fsmagic: hex value * diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 6888fc372abf..d55896f28790 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -867,6 +867,32 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) fdput(f); } +/** + * ima_measure_critical_data - measure critical data + * @event_name: name for the given data + * @event_data_source: name of the event data source + * @buf: pointer to buffer containing data to measure + * @buf_len: length of buffer(in bytes) + * @measure_buf_hash: if set to true - will measure hash of the buf, + * instead of buf + * + * Buffers can only be measured, not appraised. + */ +void ima_measure_critical_data(const char *event_name, + const char *event_data_source, + const void *buf, int buf_len, + bool measure_buf_hash) +{ + if (!event_name || !event_data_source || !buf || !buf_len) { + pr_err("Invalid arguments passed to %s().\n", __func__); + return; + } + + process_buffer_measurement(NULL, buf, buf_len, event_name, + CRITICAL_DATA, 0, event_data_source, + measure_buf_hash); +} + static int __init init_ima(void) { int error; diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 89452245f54a..491017df7589 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -510,14 +510,23 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, { int i; - if (func == KEY_CHECK) { - return (rule->flags & IMA_FUNC) && (rule->func == func) && - ima_match_rule_data(rule, rule->keyrings, func_data, - true, cred); - } if ((rule->flags & IMA_FUNC) && (rule->func != func && func != POST_SETATTR)) return false; + + switch (func) { + case KEY_CHECK: + return ((rule->func == func) && + ima_match_rule_data(rule, rule->keyrings, + func_data, true, cred)); + case CRITICAL_DATA: + return ((rule->func == func) && + ima_match_rule_data(rule, rule->data_sources, + func_data, false, cred)); + default: + break; + } + if ((rule->flags & IMA_MASK) && (rule->mask != mask && func != POST_SETATTR)) return false; @@ -1113,6 +1122,19 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) if (ima_rule_contains_lsm_cond(entry)) return false; + break; + case CRITICAL_DATA: + if (entry->action & ~(MEASURE | DONT_MEASURE)) + return false; + + if (!(entry->flags & IMA_DATA_SOURCES) || + (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR | + IMA_DATA_SOURCES))) + return false; + + if (ima_rule_contains_lsm_cond(entry)) + return false; + break; default: return false; @@ -1245,6 +1267,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) && strcmp(args[0].from, "KEY_CHECK") == 0) entry->func = KEY_CHECK; + else if (strcmp(args[0].from, "CRITICAL_DATA") == 0) + entry->func = CRITICAL_DATA; else result = -EINVAL; if (!result) From patchwork Wed Sep 23 19:20:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11795563 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4DAC0618 for ; Wed, 23 Sep 2020 19:20:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2818B2145D for ; Wed, 23 Sep 2020 19:20:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="aRdqgvrm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726784AbgIWTU2 (ORCPT ); Wed, 23 Sep 2020 15:20:28 -0400 Received: from linux.microsoft.com ([13.77.154.182]:47440 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726769AbgIWTUX (ORCPT ); Wed, 23 Sep 2020 15:20:23 -0400 Received: from tusharsu-Ubuntu.lan (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id E0E2420C27C2; Wed, 23 Sep 2020 12:20:21 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com E0E2420C27C2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1600888822; bh=reBEdoxabfOCKhw3FcEkYrdBVaobSeguzwc4Zi2Mc64=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aRdqgvrmqBjuiB3g/c60qJg38PSNvNZ4PCtZEjWIYURSuE+hJl29EJIseL8lZ4KWh Ibt5qhQSG9RI8msrtVoGbqto9S+XOIvkSgj+obdGErDc+956zeTqYN0NIjqIV/O9bi /LyHtbTduC5tCb0jkDy5+J4TqTZsJIeb3i5WrY0c= From: Tushar Sugandhi To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.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 Subject: [PATCH v4 6/6] IMA: validate supported kernel data sources before measurement Date: Wed, 23 Sep 2020 12:20:11 -0700 Message-Id: <20200923192011.5293-7-tusharsu@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923192011.5293-1-tusharsu@linux.microsoft.com> References: <20200923192011.5293-1-tusharsu@linux.microsoft.com> Precedence: bulk List-ID: Currently, IMA does not restrict random data sources from measuring their data using ima_measure_critical_data(). Any kernel data source can call the function, and it's data will get measured as long as the input event_data_source is part of the IMA policy - RITICAL_DATA+data_sources. Supporting random data sources at run-time may impact the reliability of the system. To ensure that only data from supported sources are measured, the kernel component needs to be added to a compile-time list of supported sources (an "allowed list of components"). IMA then validates the input parameter - "event_data_source" passed to ima_measure_critical_data() against this allowed list at run-time. This compile time list must be updated when kernel components are updated to measure their data using IMA. Provide an infrastructure for kernel data sources to be added to IMA's supported data sources list at compile-time. Update ima_measure_critical_data() to validate, at run-time, that the data source is supported before measuring the data coming from that source. Signed-off-by: Tushar Sugandhi --- security/integrity/ima/ima.h | 29 +++++++++++++++++++++++++++++ security/integrity/ima/ima_main.c | 6 ++++++ 2 files changed, 35 insertions(+) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index c1acf88e1b5d..4a35db010d91 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -228,6 +228,35 @@ extern const char *const func_tokens[]; struct modsig; +#define __ima_supported_kernel_data_sources(source) \ + source(MIN_SOURCE, min_source) \ + source(MAX_SOURCE, max_source) + +#define __ima_enum_stringify(ENUM, str) (#str), + +enum ima_supported_kernel_data_sources { + __ima_supported_kernel_data_sources(__ima_hook_enumify) +}; + +static const char * const ima_supported_kernel_data_sources_str[] = { + __ima_supported_kernel_data_sources(__ima_enum_stringify) +}; + +static inline bool ima_kernel_data_source_is_supported(const char *source) +{ + int i; + + if (!source) + return false; + + for (i = MIN_SOURCE + 1; i < MAX_SOURCE; i++) { + if (!strcmp(ima_supported_kernel_data_sources_str[i], source)) + return true; + } + + return false; +} + #ifdef CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS /* * To track keys that need to be measured. diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index d55896f28790..61f9642747a8 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -888,6 +888,12 @@ void ima_measure_critical_data(const char *event_name, return; } + if (!ima_kernel_data_source_is_supported(event_data_source)) { + pr_err("measuring data source %s is not permitted", + event_data_source); + return; + } + process_buffer_measurement(NULL, buf, buf_len, event_name, CRITICAL_DATA, 0, event_data_source, measure_buf_hash);