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Sun, 01 Nov 2020 17:26:37 -0500 X-MC-Unique: 0eQVawQbO5eqP_GoJXkn8A-1 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 ACC7120B4907; Sun, 1 Nov 2020 14:26:35 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com ACC7120B4907 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, paul@paul-moore.com Date: Sun, 1 Nov 2020 14:26:20 -0800 Message-Id: <20201101222626.6111-2-tusharsu@linux.microsoft.com> In-Reply-To: <20201101222626.6111-1-tusharsu@linux.microsoft.com> References: <20201101222626.6111-1-tusharsu@linux.microsoft.com> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 02 Nov 2020 02:58:01 -0500 Cc: sashal@kernel.org, dm-devel@redhat.com, selinux@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, nramas@linux.microsoft.com, linux-security-module@vger.kernel.org, tyhicks@linux.microsoft.com, linux-integrity@vger.kernel.org Subject: [dm-devel] [PATCH v5 1/7] IMA: generalize keyring specific measurement constructs X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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 them 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 | 49 ++++++++++++++++++----------- 4 files changed, 40 insertions(+), 27 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 2d1af8899cab..ae5da9f3339d 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -786,13 +786,13 @@ int ima_post_load_data(char *buf, loff_t size, * @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"; @@ -824,7 +824,7 @@ 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 9b5adeaa47fc..4edc9be62048 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -453,30 +453,44 @@ 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 + * @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 char *func_data, + const struct cred *cred) { + const struct ima_rule_opt_list *opt_list = NULL; bool matched = false; size_t i; if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid)) return false; - if (!rule->keyrings) - return true; + switch (rule->func) { + case KEY_CHECK: + if (!rule->keyrings) + return true; + else + opt_list = rule->keyrings; + break; + default: + break; + } - if (!keyring) + if (!func_data) + return false; + + if (!opt_list) 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; } @@ -493,20 +507,20 @@ 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, func_data, cred); } if ((rule->flags & IMA_FUNC) && (rule->func != func && func != POST_SETATTR)) @@ -610,8 +624,7 @@ 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. @@ -623,7 +636,7 @@ 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); @@ -638,7 +651,7 @@ 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 Sun Nov 1 22:26:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11873127 X-Patchwork-Delegate: snitzer@redhat.com 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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 5BA10C388F2 for ; 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Sun, 1 Nov 2020 22:26:40 +0000 (UTC) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by relay.mimecast.com with ESMTP id us-mta-196-0fR7FBpIP7eQSa00PfxrdQ-1; Sun, 01 Nov 2020 17:26:37 -0500 X-MC-Unique: 0fR7FBpIP7eQSa00PfxrdQ-1 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 449EF20B9C34; Sun, 1 Nov 2020 14:26:36 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 449EF20B9C34 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, paul@paul-moore.com Date: Sun, 1 Nov 2020 14:26:21 -0800 Message-Id: <20201101222626.6111-3-tusharsu@linux.microsoft.com> In-Reply-To: <20201101222626.6111-1-tusharsu@linux.microsoft.com> References: <20201101222626.6111-1-tusharsu@linux.microsoft.com> MIME-Version: 1.0 X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-MIME-Autoconverted: from quoted-printable to 8bit by lists01.pubmisc.prod.ext.phx2.redhat.com id 0A1MQh7D029354 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 02 Nov 2020 02:58:01 -0500 Cc: sashal@kernel.org, dm-devel@redhat.com, selinux@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, nramas@linux.microsoft.com, linux-security-module@vger.kernel.org, tyhicks@linux.microsoft.com, linux-integrity@vger.kernel.org Subject: [dm-devel] [PATCH v5 2/7] IMA: update process_buffer_measurement to measure buffer hash X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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 3dd8c2e4314e..be64c0bf62a7 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -347,7 +347,7 @@ 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 ae5da9f3339d..4485d87c0aa5 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -787,12 +787,15 @@ 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: 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"; @@ -807,6 +810,8 @@ 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; @@ -855,6 +860,21 @@ 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"; @@ -896,7 +916,8 @@ 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 Sun Nov 1 22:26:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11873123 X-Patchwork-Delegate: snitzer@redhat.com 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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 64A96C388F2 for ; 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Sun, 1 Nov 2020 22:26:42 +0000 (UTC) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by relay.mimecast.com with ESMTP id us-mta-76-zt8ER_NYPVe5HGTX0prIuw-1; Sun, 01 Nov 2020 17:26:38 -0500 X-MC-Unique: zt8ER_NYPVe5HGTX0prIuw-1 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 D7A1220B36E7; Sun, 1 Nov 2020 14:26:36 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com D7A1220B36E7 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, paul@paul-moore.com Date: Sun, 1 Nov 2020 14:26:22 -0800 Message-Id: <20201101222626.6111-4-tusharsu@linux.microsoft.com> In-Reply-To: <20201101222626.6111-1-tusharsu@linux.microsoft.com> References: <20201101222626.6111-1-tusharsu@linux.microsoft.com> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 02 Nov 2020 02:58:01 -0500 Cc: sashal@kernel.org, dm-devel@redhat.com, selinux@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, nramas@linux.microsoft.com, linux-security-module@vger.kernel.org, tyhicks@linux.microsoft.com, linux-integrity@vger.kernel.org Subject: [dm-devel] [PATCH v5 3/7] IMA: add hook to measure critical data X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Currently, IMA does not provide a generic function for kernel subsystems to measure their critical data. Examples of critical data in this context could be kernel in-memory r/o structures, hash of the memory structures, or data that represents a linux kernel subsystem state change. The critical data, if accidentally or maliciously altered, can compromise the integrity of the system. A generic function provided by IMA to measure critical data would enable various subsystems with easier and faster on-boarding to use IMA infrastructure and would also avoid code duplication. Add a new IMA func CRITICAL_DATA and a corresponding IMA hook ima_measure_critical_data() to support measuring critical data for various kernel subsystems. Signed-off-by: Tushar Sugandhi --- Documentation/ABI/testing/ima_policy | 2 +- include/linux/ima.h | 8 ++++++ security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_api.c | 2 +- security/integrity/ima/ima_main.c | 38 ++++++++++++++++++++++++++++ security/integrity/ima/ima_policy.c | 2 ++ 6 files changed, 51 insertions(+), 2 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index cd572912c593..3de6c774c37e 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 diff --git a/include/linux/ima.h b/include/linux/ima.h index 8fa7bcfb2da2..60ba073f1575 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -30,6 +30,10 @@ 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_data_source, + const char *event_name, + const void *buf, int buf_len, + bool measure_buf_hash); #ifdef CONFIG_IMA_KEXEC extern void ima_add_kexec_buffer(struct kimage *image); @@ -116,6 +120,10 @@ 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_data_source, + const char *event_name, + 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 4485d87c0aa5..6e1b11dcba53 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -921,6 +921,44 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) fdput(f); } +/** + * ima_measure_critical_data - measure kernel subsystem data + * critical to integrity of the kernel + * @event_data_source: name of the data source being measured; + * typically it should be the name of the kernel subsystem that is sending + * the data for measurement + * @event_name: name of an event from the kernel subsystem that is sending + * the data for measurement + * @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 + * + * A given kernel subsystem (event_data_source) may send + * data (buf) to be measured when the data or the subsystem state changes. + * The state/data change can be described by event_name. + * Examples of critical data (buf) could be kernel in-memory r/o structures, + * hash of the memory structures, or data that represents subsystem + * state change. + * measure_buf_hash can be used to save space, if the data being measured + * is too large. + * The data (buf) can only be measured, not appraised. + */ +void ima_measure_critical_data(const char *event_data_source, + const char *event_name, + 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 4edc9be62048..f48e82450fe1 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -1251,6 +1251,8 @@ 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 Sun Nov 1 22:26:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11873133 X-Patchwork-Delegate: snitzer@redhat.com 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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 0F151C4742C for ; 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Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 02 Nov 2020 02:58:01 -0500 Cc: sashal@kernel.org, dm-devel@redhat.com, selinux@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, nramas@linux.microsoft.com, linux-security-module@vger.kernel.org, tyhicks@linux.microsoft.com, linux-integrity@vger.kernel.org Subject: [dm-devel] [PATCH v5 4/7] IMA: add policy to measure critical data X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com System administrators should be able to choose which kernel subsystems they want to measure the critical data for. To enable that, an IMA policy option to choose specific kernel subsystems is needed. This policy option would constrain the measurement of the critical data to the given kernel subsystems. Add a new IMA policy option - "data_sources:=" to the IMA func CRITICAL_DATA to allow measurement of various kernel subsystems. This policy option would enable the system administrators to limit the measurement to the subsystems listed in "data_sources:=", if the subsystem measures its data by calling ima_measure_critical_data(). Limit the measurement to the subsystems that are specified in the IMA policy - CRITICAL_DATA+"data_sources:=". If "data_sources:=" is not provided with the func CRITICAL_DATA, measure the data from all the supported kernel subsystems. Signed-off-by: Tushar Sugandhi --- Documentation/ABI/testing/ima_policy | 4 ++ security/integrity/ima/ima_policy.c | 62 +++++++++++++++++++++++++--- 2 files changed, 61 insertions(+), 5 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 3de6c774c37e..15be8b16f6f3 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -48,6 +48,10 @@ 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 subsystems that contain + kernel in-memory data critical to the integrity of the kernel. + Only valid when action is "measure" and func is + CRITICAL_DATA. default policy: # PROC_SUPER_MAGIC diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index f48e82450fe1..ec99e0bb6c6f 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -34,6 +34,7 @@ #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 */ @@ -85,6 +86,7 @@ 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; }; @@ -479,6 +481,12 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule, else opt_list = rule->keyrings; break; + case CRITICAL_DATA: + if (!rule->data_sources) + return true; + else + opt_list = rule->data_sources; + break; default: break; } @@ -518,13 +526,19 @@ 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, func_data, cred); - } if ((rule->flags & IMA_FUNC) && (rule->func != func && func != POST_SETATTR)) return false; + + switch (func) { + case KEY_CHECK: + case CRITICAL_DATA: + return ((rule->func == func) && + ima_match_rule_data(rule, func_data, cred)); + default: + break; + } + if ((rule->flags & IMA_MASK) && (rule->mask != mask && func != POST_SETATTR)) return false; @@ -920,7 +934,7 @@ 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 = { @@ -957,6 +971,7 @@ 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} }; @@ -1119,6 +1134,19 @@ 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; @@ -1323,6 +1351,24 @@ 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); @@ -1703,6 +1749,12 @@ 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 Sun Nov 1 22:26:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11873125 X-Patchwork-Delegate: snitzer@redhat.com 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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 64298C00A89 for ; 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Sun, 1 Nov 2020 22:26:41 +0000 (UTC) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by relay.mimecast.com with ESMTP id us-mta-536-oM7irKBxMni_yl6NBzbFRA-1; Sun, 01 Nov 2020 17:26:39 -0500 X-MC-Unique: oM7irKBxMni_yl6NBzbFRA-1 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 127BC20BE4BC; Sun, 1 Nov 2020 14:26:38 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 127BC20BE4BC 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, paul@paul-moore.com Date: Sun, 1 Nov 2020 14:26:24 -0800 Message-Id: <20201101222626.6111-6-tusharsu@linux.microsoft.com> In-Reply-To: <20201101222626.6111-1-tusharsu@linux.microsoft.com> References: <20201101222626.6111-1-tusharsu@linux.microsoft.com> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 02 Nov 2020 02:58:01 -0500 Cc: sashal@kernel.org, dm-devel@redhat.com, selinux@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, nramas@linux.microsoft.com, linux-security-module@vger.kernel.org, tyhicks@linux.microsoft.com, linux-integrity@vger.kernel.org Subject: [dm-devel] [PATCH v5 5/7] IMA: validate supported kernel data sources before measurement X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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 - CRITICAL_DATA+data_sources. To ensure that only data from supported sources are measured, the kernel subsystem name 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 subsystems 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 | 12 ++++++++++++ 2 files changed, 41 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 6e1b11dcba53..091c2e58f3c7 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -937,6 +937,12 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) * A given kernel subsystem (event_data_source) may send * data (buf) to be measured when the data or the subsystem state changes. * The state/data change can be described by event_name. + * Before the first use of this function by a given kernel subsystem, + * the subsystem name (event_data_source) must be added to the + * compile-time list of data sources being measured - + * i.e. __ima_supported_kernel_data_sources. + * Otherwise, IMA will not measure any data for that event_data_source + * at run-time. * Examples of critical data (buf) could be kernel in-memory r/o structures, * hash of the memory structures, or data that represents subsystem * state change. @@ -954,6 +960,12 @@ void ima_measure_critical_data(const char *event_data_source, 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); From patchwork Sun Nov 1 22:26:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11873131 X-Patchwork-Delegate: snitzer@redhat.com 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=-7.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,UNWANTED_LANGUAGE_BODY 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 F341FC388F2 for ; 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Sun, 1 Nov 2020 22:26:44 +0000 (UTC) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by relay.mimecast.com with ESMTP id us-mta-415-5mhAmR_TOMidjHREeRWocA-1; Sun, 01 Nov 2020 17:26:39 -0500 X-MC-Unique: 5mhAmR_TOMidjHREeRWocA-1 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 A228920C1713; Sun, 1 Nov 2020 14:26:38 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A228920C1713 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, paul@paul-moore.com Date: Sun, 1 Nov 2020 14:26:25 -0800 Message-Id: <20201101222626.6111-7-tusharsu@linux.microsoft.com> In-Reply-To: <20201101222626.6111-1-tusharsu@linux.microsoft.com> References: <20201101222626.6111-1-tusharsu@linux.microsoft.com> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 02 Nov 2020 02:58:01 -0500 Cc: sashal@kernel.org, dm-devel@redhat.com, selinux@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, nramas@linux.microsoft.com, linux-security-module@vger.kernel.org, tyhicks@linux.microsoft.com, linux-integrity@vger.kernel.org Subject: [dm-devel] [PATCH v5 6/7] IMA: add critical_data to the built-in policy rules X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com From: Lakshmi Ramasubramanian The IMA hook to measure kernel critical data, namely ima_measure_critical_data(), could be called before a custom IMA policy is loaded. For example, SELinux calls ima_measure_critical_data() to measure its state and policy when they are initialized. This occurs before a custom IMA policy is loaded, and hence IMA hook will not measure the data. A built-in policy is therefore needed to measure critical data provided by callers before a custom IMA policy is loaded. Add CRITICAL_DATA to built-in IMA rules if the kernel command line contains "ima_policy=critical_data". Set the IMA template for this rule to "ima-buf" since ima_measure_critical_data() measures a buffer. Signed-off-by: Lakshmi Ramasubramanian --- security/integrity/ima/ima_policy.c | 32 +++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index ec99e0bb6c6f..dc8fe969d3fe 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -206,6 +206,10 @@ static struct ima_rule_entry secure_boot_rules[] __ro_after_init = { .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, }; +static struct ima_rule_entry critical_data_rules[] __ro_after_init = { + {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC}, +}; + /* An array of architecture specific rules */ static struct ima_rule_entry *arch_policy_entry __ro_after_init; @@ -228,6 +232,7 @@ __setup("ima_tcb", default_measure_policy_setup); static bool ima_use_appraise_tcb __initdata; static bool ima_use_secure_boot __initdata; +static bool ima_use_critical_data __ro_after_init; static bool ima_fail_unverifiable_sigs __ro_after_init; static int __init policy_setup(char *str) { @@ -242,6 +247,8 @@ static int __init policy_setup(char *str) ima_use_appraise_tcb = true; else if (strcmp(p, "secure_boot") == 0) ima_use_secure_boot = true; + else if (strcmp(p, "critical_data") == 0) + ima_use_critical_data = true; else if (strcmp(p, "fail_securely") == 0) ima_fail_unverifiable_sigs = true; else @@ -813,6 +820,8 @@ static int __init ima_init_arch_policy(void) void __init ima_init_policy(void) { int build_appraise_entries, arch_entries; + struct ima_template_desc *template = NULL; + int ret = 0; /* if !ima_policy, we load NO default rules */ if (ima_policy) @@ -875,6 +884,29 @@ void __init ima_init_policy(void) ARRAY_SIZE(default_appraise_rules), IMA_DEFAULT_POLICY); + if (ima_use_critical_data) { + template = lookup_template_desc("ima-buf"); + if (!template) { + ret = -EINVAL; + goto out; + } + + ret = template_desc_init_fields(template->fmt, + &(template->fields), + &(template->num_fields)); + if (ret) + goto out; + + critical_data_rules[0].template = template; 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Sun, 1 Nov 2020 14:26:39 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 3B1E6208A8F1 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, paul@paul-moore.com Date: Sun, 1 Nov 2020 14:26:26 -0800 Message-Id: <20201101222626.6111-8-tusharsu@linux.microsoft.com> In-Reply-To: <20201101222626.6111-1-tusharsu@linux.microsoft.com> References: <20201101222626.6111-1-tusharsu@linux.microsoft.com> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 02 Nov 2020 02:58:01 -0500 Cc: sashal@kernel.org, dm-devel@redhat.com, selinux@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, nramas@linux.microsoft.com, linux-security-module@vger.kernel.org, tyhicks@linux.microsoft.com, linux-integrity@vger.kernel.org Subject: [dm-devel] [PATCH v5 7/7] selinux: measure state and hash of the policy using IMA X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com From: Lakshmi Ramasubramanian Critical data structures of security modules are currently not measured. Therefore an attestation service, for instance, would not be able to attest whether the security modules are always operating with the policies and configurations that the system administrator had setup. The policies and configurations for the security modules could be tampered by rogue user mode agents or modified through some inadvertent actions on the system. Measuring such critical data would enable an attestation service to reliably assess the security configuration of the system. SELinux configuration and policy are some of the critical data for this security module that need to be measured. This measurement can be used by an attestation service, for instance, to verify if the configurations and policies have been setup correctly and that they haven't been tampered at run-time. Measure SELinux configurations, policy capabilities settings, and the hash of the loaded policy by calling the IMA hook ima_measure_critical_data(). Since the size of the loaded policy can be large (several MB), measure the hash of the policy instead of the entire policy to avoid bloating the IMA log entry. Add "selinux" to the list of supported data sources maintained by IMA to enable measuring SELinux data. To enable SELinux data measurement, the following steps are required: 1, Add "ima_policy=critical_data" to the kernel command line arguments to enable measuring SELinux data at boot time. For example, BOOT_IMAGE=/boot/vmlinuz-5.10.0-rc1+ root=UUID=fd643309-a5d2-4ed3-b10d-3c579a5fab2f ro nomodeset security=selinux ima_policy=critical_data 2, Add the following rule to /etc/ima/ima-policy measure func=CRITICAL_DATA data_sources=selinux template=ima-buf Sample measurement of SELinux state and hash of the policy: 10 e32e...5ac3 ima-buf sha256:86e8...4594 selinux-state-1595389364:287899386 696e697469616c697a65643d313b656e61626c65643d313b656e666f7263696e673d303b636865636b72657170726f743d313b6e6574776f726b5f706565725f636f6e74726f6c733d313b6f70656e5f7065726d733d313b657874656e6465645f736f636b65745f636c6173733d313b616c776179735f636865636b5f6e6574776f726b3d303b6367726f75705f7365636c6162656c3d313b6e6e705f6e6f737569645f7472616e736974696f6e3d313b67656e66735f7365636c6162656c5f73796d6c696e6b733d303 10 9e81...0857 ima-buf sha256:4941...68fc selinux-policy-hash-1597335667:462051628 8d1d...1834 To verify the measurement check the following: Execute the following command to extract the measured data from the IMA log for SELinux configuration (selinux-state). grep "selinux-state" /sys/kernel/security/integrity/ima/ascii_runtime_measurements | tail -1 | cut -d' ' -f 6 | xxd -r -p The output should be the list of key-value pairs. For example, initialized=1;enabled=1;enforcing=0;checkreqprot=1;network_peer_controls=1;open_perms=1;extended_socket_class=1;always_check_network=0;cgroup_seclabel=1;nnp_nosuid_transition=1;genfs_seclabel_symlinks=0; To verify the measured data with the current SELinux state: => enabled should be set to 1 if /sys/fs/selinux folder exists, 0 otherwise For other entries, compare the integer value in the files => /sys/fs/selinux/enforce => /sys/fs/selinux/checkreqprot And, each of the policy capabilities files under => /sys/fs/selinux/policy_capabilities Note that the actual verification would be against an expected state and done on a system other than the measured system, typically requiring "initialized=1; enabled=1;enforcing=1;checkreqprot=0;" for a secure state and then whatever policy capabilities are actually set in the expected policy (which can be extracted from the policy itself via seinfo, for example). For selinux-policy-hash, the hash of SELinux policy is included in the IMA log entry. To verify the measured data with the current SELinux policy run the following commands and verify the output hash values match. sha256sum /sys/fs/selinux/policy | cut -d' ' -f 1 grep "selinux-policy-hash" /sys/kernel/security/integrity/ima/ascii_runtime_measurements | tail -1 | cut -d' ' -f 6 Note that the actual verification of SELinux policy would require loading the expected policy into an identical kernel on a pristine/known-safe system and run the sha256sum /sys/kernel/selinux/policy there to get the expected hash. Signed-off-by: Lakshmi Ramasubramanian Suggested-by: Stephen Smalley --- Documentation/ABI/testing/ima_policy | 6 +- security/integrity/ima/ima.h | 1 + security/selinux/Makefile | 2 + security/selinux/hooks.c | 3 + security/selinux/include/security.h | 11 +- security/selinux/measure.c | 157 +++++++++++++++++++++++++++ security/selinux/selinuxfs.c | 9 ++ security/selinux/ss/services.c | 71 ++++++++++-- 8 files changed, 249 insertions(+), 11 deletions(-) create mode 100644 security/selinux/measure.c diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 15be8b16f6f3..2eb06c53a326 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -48,7 +48,7 @@ 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 subsystems that contain + data_sources:= list of kernel subsystems (eg, SeLinux) that contain kernel in-memory data critical to the integrity of the kernel. Only valid when action is "measure" and func is CRITICAL_DATA. @@ -129,3 +129,7 @@ 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 template=ima-buf diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 4a35db010d91..f10b9a368595 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -230,6 +230,7 @@ struct modsig; #define __ima_supported_kernel_data_sources(source) \ source(MIN_SOURCE, min_source) \ + source(SELINUX, selinux) \ source(MAX_SOURCE, max_source) #define __ima_enum_stringify(ENUM, str) (#str), diff --git a/security/selinux/Makefile b/security/selinux/Makefile index 4d8e0e8adf0b..83d512116341 100644 --- a/security/selinux/Makefile +++ b/security/selinux/Makefile @@ -16,6 +16,8 @@ selinux-$(CONFIG_NETLABEL) += netlabel.o selinux-$(CONFIG_SECURITY_INFINIBAND) += ibpkey.o +selinux-$(CONFIG_IMA) += measure.o + ccflags-y := -I$(srctree)/security/selinux -I$(srctree)/security/selinux/include $(addprefix $(obj)/,$(selinux-y)): $(obj)/flask.h diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 6b1826fc3658..8b9fde47ae28 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -7398,6 +7398,9 @@ int selinux_disable(struct selinux_state *state) } selinux_mark_disabled(state); + mutex_lock(&state->policy_mutex); + selinux_measure_state(state); + mutex_unlock(&state->policy_mutex); pr_info("SELinux: Disabled at runtime.\n"); diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h index 3cc8bab31ea8..18ee65c98446 100644 --- a/security/selinux/include/security.h +++ b/security/selinux/include/security.h @@ -229,7 +229,8 @@ void selinux_policy_cancel(struct selinux_state *state, struct selinux_policy *policy); int security_read_policy(struct selinux_state *state, void **data, size_t *len); - +int security_read_policy_kernel(struct selinux_state *state, + void **data, size_t *len); int security_policycap_supported(struct selinux_state *state, unsigned int req_cap); @@ -446,4 +447,12 @@ extern void ebitmap_cache_init(void); extern void hashtab_cache_init(void); extern int security_sidtab_hash_stats(struct selinux_state *state, char *page); +#ifdef CONFIG_IMA +extern void selinux_measure_state(struct selinux_state *selinux_state); +#else +static inline void selinux_measure_state(struct selinux_state *selinux_state) +{ +} +#endif + #endif /* _SELINUX_SECURITY_H_ */ diff --git a/security/selinux/measure.c b/security/selinux/measure.c new file mode 100644 index 000000000000..65d42059f588 --- /dev/null +++ b/security/selinux/measure.c @@ -0,0 +1,157 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Measure SELinux state using IMA subsystem. + */ +#include +#include +#include +#include "security.h" + +/* + * This function creates a unique name by appending the timestamp to + * the given string. This string is passed as "event_name" to the IMA + * hook to measure the given SELinux data. + * + * The data provided by SELinux to the IMA subsystem for measuring may have + * already been measured (for instance the same state existed earlier). + * But for SELinux the current data represents a state change and hence + * needs to be measured again. To enable this, pass a unique "event_name" + * to the IMA hook so that IMA subsystem will always measure the given data. + * + * For example, + * At time T0 SELinux data to be measured is "foo". IMA measures it. + * At time T1 the data is changed to "bar". IMA measures it. + * At time T2 the data is changed to "foo" again. IMA will not measure it + * (since it was already measured) unless the event_name, for instance, + * is different in this call. + */ +static char *selinux_event_name(const char *name_prefix) +{ + char *event_name = NULL; + struct timespec64 cur_time; + + ktime_get_real_ts64(&cur_time); + event_name = kasprintf(GFP_KERNEL, "%s-%lld:%09ld", name_prefix, + cur_time.tv_sec, cur_time.tv_nsec); + if (!event_name) { + pr_err("%s: event name not allocated.\n", __func__); + return NULL; + } + + return event_name; +} + +static int read_selinux_state(char **state_str, int *state_str_len, + struct selinux_state *state) +{ + char *buf, *str_fmt = "%s=%d;"; + int i, buf_len, curr; + bool initialized = selinux_initialized(state); + bool enabled = !selinux_disabled(state); + bool enforcing = enforcing_enabled(state); + bool checkreqprot = checkreqprot_get(state); + + buf_len = snprintf(NULL, 0, str_fmt, "initialized", initialized); + buf_len += snprintf(NULL, 0, str_fmt, "enabled", enabled); + buf_len += snprintf(NULL, 0, str_fmt, "enforcing", enforcing); + buf_len += snprintf(NULL, 0, str_fmt, "checkreqprot", checkreqprot); + + for (i = 0; i < __POLICYDB_CAPABILITY_MAX; i++) { + buf_len += snprintf(NULL, 0, str_fmt, + selinux_policycap_names[i], + state->policycap[i]); + } + ++buf_len; + + buf = kzalloc(buf_len, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + curr = scnprintf(buf, buf_len, str_fmt, + "initialized", initialized); + curr += scnprintf((buf + curr), (buf_len - curr), str_fmt, + "enabled", enabled); + curr += scnprintf((buf + curr), (buf_len - curr), str_fmt, + "enforcing", enforcing); + curr += scnprintf((buf + curr), (buf_len - curr), str_fmt, + "checkreqprot", checkreqprot); + + for (i = 0; i < __POLICYDB_CAPABILITY_MAX; i++) { + curr += scnprintf((buf + curr), (buf_len - curr), str_fmt, + selinux_policycap_names[i], + state->policycap[i]); + } + + *state_str = buf; + *state_str_len = curr; + + return 0; +} + +/* + * selinux_measure_state - Measure SELinux state configuration and hash of + * the SELinux policy. + * @state: selinux state struct + * + * NOTE: This function must be called with policy_mutex held. + */ +void selinux_measure_state(struct selinux_state *state) +{ + void *policy = NULL; + char *state_event_name = NULL; + char *policy_event_name = NULL; + char *state_str = NULL; + size_t policy_len; + int state_str_len, rc = 0; + bool initialized = selinux_initialized(state); + + /* + * Get a unique string for measuring the current SELinux state. + */ + state_event_name = selinux_event_name("selinux-state"); + if (!state_event_name) { + pr_err("%s: Event name for state not allocated.\n", + __func__); + rc = -ENOMEM; + goto out; + } + + rc = read_selinux_state(&state_str, &state_str_len, state); + if (rc) { + pr_err("%s: Failed to read state %d.\n", __func__, rc); + goto out; + } + + ima_measure_critical_data("selinux", state_event_name, + state_str, state_str_len, false); + + /* + * Measure SELinux policy only after initialization is completed. + */ + if (!initialized) + goto out; + + policy_event_name = selinux_event_name("selinux-policy-hash"); + if (!policy_event_name) { + pr_err("%s: Event name for policy not allocated.\n", + __func__); + rc = -ENOMEM; + goto out; + } + + rc = security_read_policy_kernel(state, &policy, &policy_len); + if (rc) { + pr_err("%s: Failed to read policy %d.\n", __func__, rc); + goto out; + } + + ima_measure_critical_data("selinux", policy_event_name, + policy, policy_len, true); + + vfree(policy); + +out: + kfree(policy_event_name); + kfree(state_str); + kfree(state_event_name); +} diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c index 4bde570d56a2..a4f1282f7178 100644 --- a/security/selinux/selinuxfs.c +++ b/security/selinux/selinuxfs.c @@ -182,6 +182,10 @@ static ssize_t sel_write_enforce(struct file *file, const char __user *buf, selinux_status_update_setenforce(state, new_value); if (!new_value) call_blocking_lsm_notifier(LSM_POLICY_CHANGE, NULL); + + mutex_lock(&state->policy_mutex); + selinux_measure_state(state); + mutex_unlock(&state->policy_mutex); } length = count; out: @@ -762,6 +766,11 @@ static ssize_t sel_write_checkreqprot(struct file *file, const char __user *buf, checkreqprot_set(fsi->state, (new_value ? 1 : 0)); length = count; + + mutex_lock(&fsi->state->policy_mutex); + selinux_measure_state(fsi->state); + mutex_unlock(&fsi->state->policy_mutex); + out: kfree(page); return length; diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index 9704c8a32303..dfa2e00894ae 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -2180,6 +2180,7 @@ static void selinux_notify_policy_change(struct selinux_state *state, selinux_status_update_policyload(state, seqno); selinux_netlbl_cache_invalidate(); selinux_xfrm_notify_policyload(); + selinux_measure_state(state); } void selinux_policy_commit(struct selinux_state *state, @@ -3875,8 +3876,33 @@ int security_netlbl_sid_to_secattr(struct selinux_state *state, } #endif /* CONFIG_NETLABEL */ +/** + * security_read_selinux_policy - read the policy. + * @policy: SELinux policy + * @data: binary policy data + * @len: length of data in bytes + * + */ +static int security_read_selinux_policy(struct selinux_policy *policy, + void *data, size_t *len) +{ + int rc; + struct policy_file fp; + + fp.data = data; + fp.len = *len; + + rc = policydb_write(&policy->policydb, &fp); + if (rc) + return rc; + + *len = (unsigned long)fp.data - (unsigned long)data; + return 0; +} + /** * security_read_policy - read the policy. + * @state: selinux_state * @data: binary policy data * @len: length of data in bytes * @@ -3885,8 +3911,6 @@ int security_read_policy(struct selinux_state *state, void **data, size_t *len) { struct selinux_policy *policy; - int rc; - struct policy_file fp; policy = rcu_dereference_protected( state->policy, lockdep_is_held(&state->policy_mutex)); @@ -3898,14 +3922,43 @@ int security_read_policy(struct selinux_state *state, if (!*data) return -ENOMEM; - fp.data = *data; - fp.len = *len; + return security_read_selinux_policy(policy, *data, len); +} - rc = policydb_write(&policy->policydb, &fp); - if (rc) - return rc; +/** + * security_read_policy_kernel - read the policy. + * @state: selinux_state + * @data: binary policy data + * @len: length of data in bytes + * + * Allocates kernel memory for reading SELinux policy. + * This function is for internal use only and should not + * be used for returning data to user space. + * + * This function must be called with policy_mutex held. + */ +int security_read_policy_kernel(struct selinux_state *state, + void **data, size_t *len) +{ + struct selinux_policy *policy; + int rc = 0; - *len = (unsigned long)fp.data - (unsigned long)*data; - return 0; + policy = rcu_dereference_protected( + state->policy, lockdep_is_held(&state->policy_mutex)); + if (!policy) { + rc = -EINVAL; + goto out; + } + + *len = policy->policydb.len; + *data = vmalloc(*len); + if (!*data) { + rc = -ENOMEM; + goto out; + } + rc = security_read_selinux_policy(policy, *data, len); + +out: + return rc; }