From patchwork Fri Jul 17 22:28:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lakshmi Ramasubramanian X-Patchwork-Id: 11671289 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 CA230138C for ; Fri, 17 Jul 2020 22:28:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2DCA20775 for ; Fri, 17 Jul 2020 22:28:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="DCCbwIq6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726710AbgGQW2o (ORCPT ); Fri, 17 Jul 2020 18:28:44 -0400 Received: from linux.microsoft.com ([13.77.154.182]:46032 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726399AbgGQW2Z (ORCPT ); Fri, 17 Jul 2020 18:28:25 -0400 Received: from localhost.localdomain (c-73-42-176-67.hsd1.wa.comcast.net [73.42.176.67]) by linux.microsoft.com (Postfix) with ESMTPSA id 7C0B720B490A; Fri, 17 Jul 2020 15:28:24 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 7C0B720B490A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1595024904; bh=JPlRumbOfvyOco8L8nkT1d2Rp+0/lx8FfGi5jva830E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DCCbwIq6QToosLKT/34ObzUnj4GPjjOKO67Ms012lwH0qYgstUMs+s4mlCfKpXk+L Q/12+DzCBzyfH6ZZma/MSoJi3oWZrQKBCc9K5HA8QpRHEASPXwoAMd0IsKiXoRY3Kf cRnjoU3IlDcUmOFkddOaJ4IE0vecgRhfW40/MyYQ= From: Lakshmi Ramasubramanian To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com Cc: jmorris@namei.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/5] IMA: Add LSM_STATE func to measure LSM data Date: Fri, 17 Jul 2020 15:28:15 -0700 Message-Id: <20200717222819.26198-2-nramas@linux.microsoft.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200717222819.26198-1-nramas@linux.microsoft.com> References: <20200717222819.26198-1-nramas@linux.microsoft.com> MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Critical data structures of security modules need to be measured to enable an attestation service to verify if the policies and configuration have been setup correctly and that they haven't been tampered with at runtime. A new IMA policy is required for handling this measurement. Define a new IMA policy func namely LSM_STATE to measure data provided by security modules. Update ima_match_rules() to check for LSM_STATE and ima_parse_rule() to handle LSM_STATE. Signed-off-by: Lakshmi Ramasubramanian --- Documentation/ABI/testing/ima_policy | 6 +++++- security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_api.c | 2 +- security/integrity/ima/ima_policy.c | 29 +++++++++++++++++++++++----- 4 files changed, 31 insertions(+), 7 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index cd572912c593..355bc3eade33 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] [LSM_STATE] mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] [[^]MAY_EXEC] fsmagic:= hex value @@ -125,3 +125,7 @@ Description: keys added to .builtin_trusted_keys or .ima keyring: measure func=KEY_CHECK keyrings=.builtin_trusted_keys|.ima + + Example of measure rule using LSM_STATE to measure LSM data: + + measure func=LSM_STATE diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 4515975cc540..880fda11a61b 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(LSM_STATE, lsm_state) \ 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 bf22de8b7ce0..0cebd2404dcf 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 | LSM_STATE * mask: contains the permission mask * fsmagic: hex value * diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 66aa3e17a888..fc8457d9242b 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -417,15 +417,31 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, const char *keyring) { int i; + int funcmatch = 0; - if ((func == KEXEC_CMDLINE) || (func == KEY_CHECK)) { + switch (func) { + case KEXEC_CMDLINE: + case KEY_CHECK: + case LSM_STATE: if ((rule->flags & IMA_FUNC) && (rule->func == func)) { if (func == KEY_CHECK) - return ima_match_keyring(rule, keyring, cred); - return true; - } - return false; + funcmatch = ima_match_keyring(rule, keyring, + cred) ? 1 : -1; + else + funcmatch = 1; + } else + funcmatch = -1; + + break; + + default: + funcmatch = 0; + break; } + + if (funcmatch) + return (funcmatch == 1) ? true : false; + if ((rule->flags & IMA_FUNC) && (rule->func != func && func != POST_SETATTR)) return false; @@ -1068,6 +1084,9 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) entry->func = KEXEC_CMDLINE; else if (strcmp(args[0].from, "KEY_CHECK") == 0) entry->func = KEY_CHECK; + else if (strcmp(args[0].from, "LSM_STATE") == 0) + entry->func = LSM_STATE; + else result = -EINVAL; if (!result) From patchwork Fri Jul 17 22:28:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lakshmi Ramasubramanian X-Patchwork-Id: 11671281 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 5D5DC138C for ; Fri, 17 Jul 2020 22:28:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 436142074B for ; Fri, 17 Jul 2020 22:28:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="YVfP40hE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726784AbgGQW2Z (ORCPT ); Fri, 17 Jul 2020 18:28:25 -0400 Received: from linux.microsoft.com ([13.77.154.182]:46040 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726546AbgGQW2Z (ORCPT ); Fri, 17 Jul 2020 18:28:25 -0400 Received: from localhost.localdomain (c-73-42-176-67.hsd1.wa.comcast.net [73.42.176.67]) by linux.microsoft.com (Postfix) with ESMTPSA id BC35920B490C; Fri, 17 Jul 2020 15:28:24 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com BC35920B490C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1595024904; bh=uMfFSH8BKWRMGn0Ob/aAF/poLIpxKXFWWoJsEWCn7j0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YVfP40hEnxBsKkwDeaxnVTMhc7LN7IT8kG8YcZ+ZXHu9cM6KjnnrKLqydpNGLSBC/ 1WHUTzTnZdL7VM6F1hSZVAsjadaMffIan9wEG6BxnZbKwrwHfvHDSZBqcORhYY9OJC akYfBlGr526lVXP3W2Gz/Qnt67RIunVSwQzSGZvE= From: Lakshmi Ramasubramanian To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com Cc: jmorris@namei.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/5] IMA: Define an IMA hook to measure LSM data Date: Fri, 17 Jul 2020 15:28:16 -0700 Message-Id: <20200717222819.26198-3-nramas@linux.microsoft.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200717222819.26198-1-nramas@linux.microsoft.com> References: <20200717222819.26198-1-nramas@linux.microsoft.com> MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org IMA subsystem needs to define an IMA hook that the security modules can call to measure critical data of the security modules. Define a new IMA hook, namely ima_lsm_state(), that the security modules can call to measure data. Signed-off-by: Lakshmi Ramasubramanian --- include/linux/ima.h | 4 ++++ security/integrity/ima/ima_main.c | 17 +++++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/include/linux/ima.h b/include/linux/ima.h index 9164e1534ec9..7e2686f4953a 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -26,6 +26,7 @@ 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(const void *buf, int size); +extern void ima_lsm_state(const char *lsm_event_name, const void *buf, int size); #ifdef CONFIG_IMA_KEXEC extern void ima_add_kexec_buffer(struct kimage *image); @@ -104,6 +105,9 @@ static inline int ima_file_hash(struct file *file, char *buf, size_t buf_size) } static inline void ima_kexec_cmdline(const void *buf, int size) {} + +static inline void ima_lsm_state(const char *lsm_event_name, + const void *buf, int size) {} #endif /* CONFIG_IMA */ #ifndef CONFIG_IMA_KEXEC diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 8351b2fd48e0..04d9a1d35300 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -835,6 +835,23 @@ void ima_kexec_cmdline(const void *buf, int size) KEXEC_CMDLINE, 0, NULL); } +/** + * ima_lsm_state - measure LSM specific state + * @lsm_event_name: LSM event + * @buf: pointer to buffer containing LSM specific state + * @size: Number of bytes in buf + * + * Buffers can only be measured, not appraised. + */ +void ima_lsm_state(const char *lsm_event_name, const void *buf, int size) +{ + if (!lsm_event_name || !buf || !size) + return; + + process_buffer_measurement(buf, size, lsm_event_name, + LSM_STATE, 0, NULL); +} + static int __init init_ima(void) { int error; From patchwork Fri Jul 17 22:28:17 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lakshmi Ramasubramanian X-Patchwork-Id: 11671275 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 3F185138C for ; Fri, 17 Jul 2020 22:28:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 25D242074B for ; Fri, 17 Jul 2020 22:28:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="V+RNQ9Dj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726898AbgGQW20 (ORCPT ); Fri, 17 Jul 2020 18:28:26 -0400 Received: from linux.microsoft.com ([13.77.154.182]:46056 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726656AbgGQW20 (ORCPT ); Fri, 17 Jul 2020 18:28:26 -0400 Received: from localhost.localdomain (c-73-42-176-67.hsd1.wa.comcast.net [73.42.176.67]) by linux.microsoft.com (Postfix) with ESMTPSA id 0870920B490D; Fri, 17 Jul 2020 15:28:25 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 0870920B490D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1595024905; bh=IdQSrPA8ty21hAGthr+LlcK7k1tepvn9UlOK08+4/Kg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V+RNQ9DjFg302EnaTWPLdcf3JXEfSbkdWIONz1UOoB1n5ib/WysXq062Vib+Pwwql IDhocOQQ842tF7tqJi/Rldjxz/KCmTzamnBV+GVPW9Xs7lij6SIlnpvvnDsz11/lck ihWY6m2NAIqA5AvYWJxcsj7Vnt3HqUUwQ0pqyv8s= From: Lakshmi Ramasubramanian To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com Cc: jmorris@namei.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 3/5] LSM: Add security_measure_data in lsm_info struct Date: Fri, 17 Jul 2020 15:28:17 -0700 Message-Id: <20200717222819.26198-4-nramas@linux.microsoft.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200717222819.26198-1-nramas@linux.microsoft.com> References: <20200717222819.26198-1-nramas@linux.microsoft.com> MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org The security modules that require their data to be measured using the IMA subsystem need to define a function that the LSM can call to trigger the measurement. Add a function pointer field namely security_measure_data in lsm_info structure. Update LSM to call this security module function, if defined, to measure the security module's data using the IMA subsystem. Signed-off-by: Lakshmi Ramasubramanian --- include/linux/lsm_hooks.h | 3 +++ security/security.c | 48 ++++++++++++++++++++++++++++++++++++++- 2 files changed, 50 insertions(+), 1 deletion(-) diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 95b7c1d32062..17afdf319c55 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1591,6 +1591,9 @@ struct lsm_info { int *enabled; /* Optional: controlled by CONFIG_LSM */ int (*init)(void); /* Required. */ struct lsm_blob_sizes *blobs; /* Optional: for blob sharing. */ + void (*security_measure_data)(void); /* Optional: for measuring + * security module data. + */ }; extern struct lsm_info __start_lsm_info[], __end_lsm_info[]; diff --git a/security/security.c b/security/security.c index 70a7ad357bc6..88ce1b780ffd 100644 --- a/security/security.c +++ b/security/security.c @@ -86,6 +86,9 @@ static __initconst const char * const builtin_lsm_order = CONFIG_LSM; static __initdata struct lsm_info **ordered_lsms; static __initdata struct lsm_info *exclusive; +static struct lsm_info *security_state_lsms; +static int security_state_lsms_count; + static __initdata bool debug; #define init_debug(...) \ do { \ @@ -235,6 +238,45 @@ static void __init initialize_lsm(struct lsm_info *lsm) } } +static void measure_security_state(struct lsm_info *lsm) +{ + if (!lsm->security_measure_data) + return; + + lsm->security_measure_data(); +} + +static void __init initialize_security_state_lsms(void) +{ + struct lsm_info **lsm; + int count = 0; + int inx; + + for (lsm = ordered_lsms; *lsm; lsm++) { + if ((*lsm)->security_measure_data) + count++; + } + + if (count == 0) + return; + + security_state_lsms = kcalloc(count, sizeof(struct lsm_info), + GFP_KERNEL); + if (!security_state_lsms) + return; + + inx = 0; + for (lsm = ordered_lsms; *lsm; lsm++) { + if ((*lsm)->security_measure_data) { + security_state_lsms[inx].security_measure_data = + (*lsm)->security_measure_data; + inx++; + } + } + + security_state_lsms_count = count; +} + /* Populate ordered LSMs list from comma-separated LSM name list. */ static void __init ordered_lsm_parse(const char *order, const char *origin) { @@ -352,8 +394,12 @@ static void __init ordered_lsm_init(void) lsm_early_cred((struct cred *) current->cred); lsm_early_task(current); - for (lsm = ordered_lsms; *lsm; lsm++) + for (lsm = ordered_lsms; *lsm; lsm++) { initialize_lsm(*lsm); + measure_security_state(*lsm); + } + + initialize_security_state_lsms(); kfree(ordered_lsms); } From patchwork Fri Jul 17 22:28:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lakshmi Ramasubramanian X-Patchwork-Id: 11671269 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 57F8A161F for ; Fri, 17 Jul 2020 22:28:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 361FC2074B for ; Fri, 17 Jul 2020 22:28:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="qpdTMKfT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726761AbgGQW2d (ORCPT ); Fri, 17 Jul 2020 18:28:33 -0400 Received: from linux.microsoft.com ([13.77.154.182]:46066 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726710AbgGQW21 (ORCPT ); Fri, 17 Jul 2020 18:28:27 -0400 Received: from localhost.localdomain (c-73-42-176-67.hsd1.wa.comcast.net [73.42.176.67]) by linux.microsoft.com (Postfix) with ESMTPSA id 46CC220B490E; Fri, 17 Jul 2020 15:28:25 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 46CC220B490E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1595024905; bh=FlxPpoHRlEy/uLV0zIbVvaBsQsJDtwjFtee4zr3BQuQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qpdTMKfTRByOmxb6FUqMUf73lw6pUZIoQLqYguT0Kb4mZCaV5tvhiE/BzwCMC5pI6 JLUiy1Tzf7lOPLMOm2bnfRckqTjHtbLVw4p7jC4cD6n7HNnG1i/WVmHbNlC9jj6r1z vGam79+Lxo481uw+DodhGbAdQwEsE2mf9ZIoxQ6U= From: Lakshmi Ramasubramanian To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com Cc: jmorris@namei.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 4/5] LSM: Define SELinux function to measure security state Date: Fri, 17 Jul 2020 15:28:18 -0700 Message-Id: <20200717222819.26198-5-nramas@linux.microsoft.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200717222819.26198-1-nramas@linux.microsoft.com> References: <20200717222819.26198-1-nramas@linux.microsoft.com> MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org SELinux configuration and policy are some of the critical data for this security module that needs to be measured. To enable this measurement SELinux needs to implement the interface function, security_measure_data(), that the LSM can call. Define the security_measure_data() function in SELinux to measure SELinux configuration and policy. Call this function to measure SELinux data when there is a change in the security module's state. Sample measurement of SELinux state and hash of the policy: 10 e32e...5ac3 ima-buf sha256:86e8...4594 selinux-state 656e61626c65643d313b656e666f7263696e673d303b636865636b72657170726f743d313b6e6574706565723d313b6f70656e7065726d3d313b657874736f636b636c6173733d313b616c776179736e6574776f726b3d303b6367726f75707365636c6162656c3d313b6e6e706e6f737569647472616e736974696f6e3d313b67656e66737365636c6162656c73796d6c696e6b3d303b 10 f4a7...9408 ima-buf sha256:4941...68fc selinux-policy-hash 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). cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | grep -m 1 "selinux-state" | cut -d' ' -f 6 | xxd -r -p The output should be the list of key-value pairs. For example, 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 The data for selinux-policy-hash is the SHA256 hash of SELinux policy. 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 cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | grep -m 1 "selinux-policy-hash" | cut -d' ' -f 6 Signed-off-by: Lakshmi Ramasubramanian Suggested-by: Stephen Smalley Reported-by: kernel test robot Reported-by: kernel test robot Reported-by: kernel test robot --- security/selinux/Makefile | 2 + security/selinux/hooks.c | 4 + security/selinux/include/security.h | 18 ++++ security/selinux/measure.c | 155 ++++++++++++++++++++++++++++ security/selinux/selinuxfs.c | 1 + security/selinux/ss/services.c | 66 ++++++++++-- 6 files changed, 237 insertions(+), 9 deletions(-) create mode 100644 security/selinux/measure.c 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 efa6108b1ce9..cda1d328339f 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -7259,6 +7259,8 @@ static __init int selinux_init(void) fs_validate_description("selinux", selinux_fs_parameters); + selinux_init_measurement(); + return 0; } @@ -7284,6 +7286,7 @@ DEFINE_LSM(selinux) = { .enabled = &selinux_enabled_boot, .blobs = &selinux_blob_sizes, .init = selinux_init, + .security_measure_data = selinux_measure_data, }; #if defined(CONFIG_NETFILTER) @@ -7394,6 +7397,7 @@ int selinux_disable(struct selinux_state *state) } selinux_mark_disabled(state); + selinux_measure_state(state); pr_info("SELinux: Disabled at runtime.\n"); diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h index b0e02cfe3ce1..1f41c16a4845 100644 --- a/security/selinux/include/security.h +++ b/security/selinux/include/security.h @@ -222,16 +222,34 @@ static inline bool selinux_policycap_genfs_seclabel_symlinks(void) return state->policycap[POLICYDB_CAPABILITY_GENFS_SECLABEL_SYMLINKS]; } +static inline bool selinux_checkreqprot(const struct selinux_state *state) +{ + return READ_ONCE(state->checkreqprot); +} + int security_mls_enabled(struct selinux_state *state); int security_load_policy(struct selinux_state *state, void *data, size_t len); 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); size_t security_policydb_len(struct selinux_state *state); int security_policycap_supported(struct selinux_state *state, unsigned int req_cap); +#ifdef CONFIG_IMA +extern void __init selinux_init_measurement(void); +extern void selinux_measure_data(void); +extern void selinux_measure_state(struct selinux_state *selinux_state); +#else +static inline void __init selinux_init_measurement(void) {} +static inline void selinux_measure_data(void) {} +static inline void selinux_measure_state( + struct selinux_state *selinux_state) {} +#endif + #define SEL_VEC_MAX 32 struct av_decision { u32 allowed; diff --git a/security/selinux/measure.c b/security/selinux/measure.c new file mode 100644 index 000000000000..659011637ae7 --- /dev/null +++ b/security/selinux/measure.c @@ -0,0 +1,155 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Measure SELinux state using IMA subsystem. + */ +#include +#include "security.h" + +/* Pre-allocated buffer used for measuring state */ +static char *selinux_state_string; +static size_t selinux_state_string_len; +static char *str_format = "%s=%d;"; +static int selinux_state_count; + +void __init selinux_init_measurement(void) +{ + int i; + + /* + * enabled + * enforcing + * checkreqport + * All policy capability flags + */ + selinux_state_count = 3 + __POLICYDB_CAPABILITY_MAX; + + selinux_state_string_len = snprintf(NULL, 0, str_format, + "enabled", 0); + selinux_state_string_len += snprintf(NULL, 0, str_format, + "enforcing", 0); + selinux_state_string_len += snprintf(NULL, 0, str_format, + "checkreqprot", 0); + for (i = 3; i < selinux_state_count; i++) { + selinux_state_string_len += + snprintf(NULL, 0, str_format, + selinux_policycap_names[i-3], 0); + } + ++selinux_state_string_len; + + selinux_state_string = kzalloc(selinux_state_string_len, GFP_KERNEL); + if (!selinux_state_string) { + pr_warn("Failed to alloc memory for SELinux measurement\n"); + selinux_state_string_len = 0; + } +} + +static int selinux_hash_policy(const char *hash_alg_name, + void *policy, size_t policy_len, + void **policy_hash, int *policy_hash_len) +{ + struct crypto_shash *tfm; + struct shash_desc *desc = NULL; + void *digest = NULL; + int desc_size; + int digest_size; + int ret = 0; + + tfm = crypto_alloc_shash(hash_alg_name, 0, 0); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); + digest_size = crypto_shash_digestsize(tfm); + + digest = kmalloc(digest_size, GFP_KERNEL); + if (!digest) { + ret = -ENOMEM; + goto error; + } + + desc = kzalloc(desc_size, GFP_KERNEL); + if (!desc) { + ret = -ENOMEM; + goto error; + } + + desc->tfm = tfm; + + ret = crypto_shash_digest(desc, policy, policy_len, digest); + if (ret < 0) + goto error; + + *policy_hash_len = digest_size; + *policy_hash = digest; + digest = NULL; + +error: + kfree(desc); + kfree(digest); + + crypto_free_shash(tfm); + + return ret; +} + +void selinux_measure_state(struct selinux_state *selinux_state) +{ + void *policy = NULL; + void *policy_hash = NULL; + size_t curr, buflen; + int i, policy_hash_len, rc = 0; + + if (!selinux_initialized(selinux_state)) { + pr_warn("%s: SELinux not yet initialized.\n", __func__); + return; + } + + if (!selinux_state_string) { + pr_warn("%s: Buffer for state not allocated.\n", __func__); + return; + } + + curr = snprintf(selinux_state_string, selinux_state_string_len, + str_format, "enabled", + !selinux_disabled(selinux_state)); + curr += snprintf((selinux_state_string + curr), + (selinux_state_string_len - curr), + str_format, "enforcing", + enforcing_enabled(selinux_state)); + curr += snprintf((selinux_state_string + curr), + (selinux_state_string_len - curr), + str_format, "checkreqprot", + selinux_checkreqprot(selinux_state)); + + for (i = 3; i < selinux_state_count; i++) { + curr += snprintf((selinux_state_string + curr), + (selinux_state_string_len - curr), + str_format, + selinux_policycap_names[i - 3], + selinux_state->policycap[i - 3]); + } + + if (curr >= 0 && curr < selinux_state_string_len) + ima_lsm_state("selinux-state", selinux_state_string, curr); + else { + rc = -EINVAL; + goto out; + } + + rc = security_read_policy_kernel(selinux_state, &policy, &buflen); + if (!rc) + rc = selinux_hash_policy("sha256", policy, buflen, + &policy_hash, &policy_hash_len); + if (!rc) + ima_lsm_state("selinux-policy-hash", policy_hash, + policy_hash_len); + +out: + vfree(policy); + kfree(policy_hash); +} + +void selinux_measure_data(void) +{ + selinux_measure_state(&selinux_state); +} diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c index 4781314c2510..b1f70739d709 100644 --- a/security/selinux/selinuxfs.c +++ b/security/selinux/selinuxfs.c @@ -173,6 +173,7 @@ static ssize_t sel_write_enforce(struct file *file, const char __user *buf, from_kuid(&init_user_ns, audit_get_loginuid(current)), audit_get_sessionid(current)); enforcing_set(state, new_value); + selinux_measure_state(&selinux_state); if (new_value) avc_ss_reset(state->avc, 0); selnl_notify_setenforce(new_value); diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index ef0afd878bfc..79a6b462f1fe 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -3720,14 +3720,22 @@ int security_netlbl_sid_to_secattr(struct selinux_state *state, } #endif /* CONFIG_NETLABEL */ +static int security_read_policy_len(struct selinux_state *state, size_t *len) +{ + if (!selinux_initialized(state)) + return -EINVAL; + + *len = security_policydb_len(state); + return 0; +} + /** * security_read_policy - read the policy. * @data: binary policy data * @len: length of data in bytes - * */ -int security_read_policy(struct selinux_state *state, - void **data, size_t *len) +int security_read_selinux_policy(struct selinux_state *state, + void **data, size_t *len) { struct policydb *policydb = &state->ss->policydb; int rc; @@ -3736,12 +3744,6 @@ int security_read_policy(struct selinux_state *state, if (!selinux_initialized(state)) return -EINVAL; - *len = security_policydb_len(state); - - *data = vmalloc_user(*len); - if (!*data) - return -ENOMEM; - fp.data = *data; fp.len = *len; @@ -3754,5 +3756,51 @@ int security_read_policy(struct selinux_state *state, *len = (unsigned long)fp.data - (unsigned long)*data; return 0; +} + +/** + * security_read_policy - read the policy. + * @data: binary policy data + * @len: length of data in bytes + * + */ +int security_read_policy(struct selinux_state *state, + void **data, size_t *len) +{ + int rc; + + rc = security_read_policy_len(state, len); + if (rc) + return rc; + + *data = vmalloc_user(*len); + if (!*data) + return -ENOMEM; + + return security_read_selinux_policy(state, data, len); +} + +/** + * security_read_policy_kernel - read the policy. + * @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 + */ +int security_read_policy_kernel(struct selinux_state *state, + void **data, size_t *len) +{ + int rc; + + rc = security_read_policy_len(state, len); + if (rc) + return rc; + + *data = vmalloc(*len); + if (!*data) + return -ENOMEM; + return security_read_selinux_policy(state, data, len); } From patchwork Fri Jul 17 22:28:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lakshmi Ramasubramanian X-Patchwork-Id: 11671261 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 39713161F for ; Fri, 17 Jul 2020 22:28:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2211220739 for ; Fri, 17 Jul 2020 22:28:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="U4egA04G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726945AbgGQW20 (ORCPT ); Fri, 17 Jul 2020 18:28:26 -0400 Received: from linux.microsoft.com ([13.77.154.182]:46074 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726761AbgGQW20 (ORCPT ); Fri, 17 Jul 2020 18:28:26 -0400 Received: from localhost.localdomain (c-73-42-176-67.hsd1.wa.comcast.net [73.42.176.67]) by linux.microsoft.com (Postfix) with ESMTPSA id 8A2BC20B490F; Fri, 17 Jul 2020 15:28:25 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 8A2BC20B490F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1595024905; bh=V1TG6A62AlhkeMm5nI6RacUJ4gr3crF9A3ZVYUcYMRs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U4egA04GbOb67I6EwS8hIDOLDfPZ06IiIRb3g7gaFNjxo466qCpZF4nkvZpZAKO7s V6Fhr3J6GGOS2P5TGri9M0E+xGgHfALxR0d25Nqn6al9LhixozKO0Psk2hSnXopPh9 210GfbhPj9HlOC+R4Nk/O4dEShIPGeylZeSpHJLQ= From: Lakshmi Ramasubramanian To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com Cc: jmorris@namei.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 5/5] LSM: Define workqueue for measuring security module state Date: Fri, 17 Jul 2020 15:28:19 -0700 Message-Id: <20200717222819.26198-6-nramas@linux.microsoft.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200717222819.26198-1-nramas@linux.microsoft.com> References: <20200717222819.26198-1-nramas@linux.microsoft.com> MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Data structures critical to the functioning of a security module could be tampered with by malware or changed inadvertently at runtime thereby disabling or reducing the security guarantees provided by the security module. Such critical data need to be periodically checked and measured, if there is any change. This would enable an attestation service, for instance, to verify that the security modules are operating with the configuration and policy setup by the system administrator. Define a workqueue in the LSM and invoke the security modules in the workqueue handler to check their data and measure. Note that the data given by the security module would be measured by the IMA subsystem only if it has changed since the last time it was measured. Signed-off-by: Lakshmi Ramasubramanian --- security/security.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/security/security.c b/security/security.c index 88ce1b780ffd..6e746a024ed5 100644 --- a/security/security.c +++ b/security/security.c @@ -89,6 +89,11 @@ static __initdata struct lsm_info *exclusive; static struct lsm_info *security_state_lsms; static int security_state_lsms_count; +static long security_state_timeout = 300000; /* 5 Minutes */ +static void security_state_handler(struct work_struct *work); +static DECLARE_DELAYED_WORK(security_state_delayed_work, + security_state_handler); + static __initdata bool debug; #define init_debug(...) \ do { \ @@ -277,6 +282,26 @@ static void __init initialize_security_state_lsms(void) security_state_lsms_count = count; } +static void initialize_security_state_monitor(void) +{ + if (security_state_lsms_count == 0) + return; + + schedule_delayed_work(&security_state_delayed_work, + msecs_to_jiffies(security_state_timeout)); +} + +static void security_state_handler(struct work_struct *work) +{ + int inx; + + for (inx = 0; inx < security_state_lsms_count; inx++) + measure_security_state(&(security_state_lsms[inx])); + + schedule_delayed_work(&security_state_delayed_work, + msecs_to_jiffies(security_state_timeout)); +} + /* Populate ordered LSMs list from comma-separated LSM name list. */ static void __init ordered_lsm_parse(const char *order, const char *origin) { @@ -400,6 +425,7 @@ static void __init ordered_lsm_init(void) } initialize_security_state_lsms(); + initialize_security_state_monitor(); kfree(ordered_lsms); }