From patchwork Wed Oct 4 22:09:36 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fan Wu X-Patchwork-Id: 13409545 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8CB6EE9370C for ; Wed, 4 Oct 2023 22:10:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236547AbjJDWKL (ORCPT ); Wed, 4 Oct 2023 18:10:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233822AbjJDWJ6 (ORCPT ); Wed, 4 Oct 2023 18:09:58 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id A74DCFB; Wed, 4 Oct 2023 15:09:53 -0700 (PDT) Received: by linux.microsoft.com (Postfix, from userid 1052) id A87EC20B74D2; Wed, 4 Oct 2023 15:09:50 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A87EC20B74D2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1696457390; bh=3Nri8oDOekV6L4vSrwk6hrgqfGo/+ps3Zz2m4l0TszM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iJymOh1bxlwp5gixbtHY+bnBz11JHVppmjyJIhT/CW1IpH0MWiKg8xg7EAyend2cq 5YaMeLBKNPBND3U/lal+63vPKTfk162FrTD241z8mCBCedUXV+YR8dlr9Wp8DW6v9R 9/J/eHQUm9eb6F3PAultRk2OkwmFqPJXcukDBzck= From: Fan Wu To: corbet@lwn.net, zohar@linux.ibm.com, jmorris@namei.org, serge@hallyn.com, tytso@mit.edu, ebiggers@kernel.org, axboe@kernel.dk, agk@redhat.com, snitzer@kernel.org, eparis@redhat.com, paul@paul-moore.com Cc: linux-doc@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-block@vger.kernel.org, dm-devel@redhat.com, audit@vger.kernel.org, roberto.sassu@huawei.com, linux-kernel@vger.kernel.org, Deven Bowers , Fan Wu Subject: [RFC PATCH v11 09/19] ipe: add permissive toggle Date: Wed, 4 Oct 2023 15:09:36 -0700 Message-Id: <1696457386-3010-10-git-send-email-wufan@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1696457386-3010-1-git-send-email-wufan@linux.microsoft.com> References: <1696457386-3010-1-git-send-email-wufan@linux.microsoft.com> Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org From: Deven Bowers IPE, like SELinux, supports a permissive mode. This mode allows policy authors to test and evaluate IPE policy without it effecting their programs. When the mode is changed, a 1404 AUDIT_MAC_STATUS be reported. This patch adds the following audit records: audit: MAC_STATUS enforcing=0 old_enforcing=1 auid=4294967295 ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1 audit: MAC_STATUS enforcing=1 old_enforcing=0 auid=4294967295 ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1 The audit record only emit when the value from the user input is different from the current enforce value. Signed-off-by: Deven Bowers Signed-off-by: Fan Wu --- v2: + Split evaluation loop, access control hooks, and evaluation loop from policy parser and userspace interface to pass mailing list character limit v3: + Move ipe_load_properties to patch 04. + Remove useless 0-initializations + Prefix extern variables with ipe_ + Remove kernel module parameters, as these are exposed through sysctls. + Add more prose to the IPE base config option help text. + Use GFP_KERNEL for audit_log_start. + Remove unnecessary caching system. + Remove comments from headers + Use rcu_access_pointer for rcu-pointer null check + Remove usage of reqprot; use prot only. + Move policy load and activation audit event to 03/12 v4: + Remove sysctls in favor of securityfs nodes + Re-add kernel module parameters, as these are now exposed through securityfs. + Refactor property audit loop to a separate function. v5: + fix minor grammatical errors + do not group rule by curly-brace in audit record, reconstruct the exact rule. v6: + No changes v7: + Further split lsm creation into a separate commit from the evaluation loop and audit system, for easier review. + Propagating changes to support the new ipe_context structure in the evaluation loop. + Split out permissive functionality into a separate patch for easier review. + Remove permissive switch compile-time configuration option - this is trivial to add later. v8: + Remove "IPE" prefix from permissive audit record + align fields to the linux-audit field dictionary. This causes the following fields to change: enforce -> permissive + Remove duplicated information correlated with syscall record, that will always be present in the audit event. + Change audit types: + AUDIT_TRUST_STATUS -> AUDIT_MAC_STATUS + There is no significant difference in meaning between these types. v9: + Clean up ipe_context related code v10: + Change audit format to comform with the existing format selinux is using + Remove the audit record emission during init to align with selinux, which does not perform this action. v11: + Remove redundant code --- security/ipe/audit.c | 22 ++++++++++++++ security/ipe/audit.h | 1 + security/ipe/eval.c | 14 +++++++-- security/ipe/eval.h | 1 + security/ipe/fs.c | 68 ++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 104 insertions(+), 2 deletions(-) diff --git a/security/ipe/audit.c b/security/ipe/audit.c index e123701d5e3b..0dd5f10c318f 100644 --- a/security/ipe/audit.c +++ b/security/ipe/audit.c @@ -193,3 +193,25 @@ void ipe_audit_policy_load(const struct ipe_policy *const p) audit_log_end(ab); } + +/** + * ipe_audit_enforce - Audit a change in IPE's enforcement state. + * @new_enforce: The new value enforce to be set. + * @old_enforce: The old value currently in enforce. + */ +void ipe_audit_enforce(bool new_enforce, bool old_enforce) +{ + struct audit_buffer *ab; + + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS); + if (!ab) + return; + + audit_log_format(ab, "enforcing=%d old_enforcing=%d auid=%u ses=%u" + " enabled=1 old-enabled=1 lsm=ipe res=1", + new_enforce, old_enforce, + from_kuid(&init_user_ns, audit_get_loginuid(current)), + audit_get_sessionid(current)); + + audit_log_end(ab); +} diff --git a/security/ipe/audit.h b/security/ipe/audit.h index 0ff5a06808de..914f001e5286 100644 --- a/security/ipe/audit.h +++ b/security/ipe/audit.h @@ -14,5 +14,6 @@ void ipe_audit_match(const struct ipe_eval_ctx *const ctx, void ipe_audit_policy_load(const struct ipe_policy *const p); void ipe_audit_policy_activation(const struct ipe_policy *const op, const struct ipe_policy *const np); +void ipe_audit_enforce(bool new_enforce, bool old_enforce); #endif /* _IPE_AUDIT_H */ diff --git a/security/ipe/eval.c b/security/ipe/eval.c index 499b6b3338f2..78c54ff1fdd3 100644 --- a/security/ipe/eval.c +++ b/security/ipe/eval.c @@ -19,6 +19,7 @@ struct ipe_policy __rcu *ipe_active_policy; bool success_audit; +bool enforce = true; static const struct super_block *pinned_sb; static DEFINE_SPINLOCK(pin_lock); @@ -114,12 +115,14 @@ static bool evaluate_property(const struct ipe_eval_ctx *const ctx, int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) { bool match = false; + bool enforcing = true; enum ipe_action_type action; enum ipe_match match_type; struct ipe_policy *pol = NULL; const struct ipe_rule *rule = NULL; const struct ipe_op_table *rules = NULL; struct ipe_prop *prop = NULL; + int rc = 0; rcu_read_lock(); @@ -129,6 +132,8 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) return 0; } + enforcing = READ_ONCE(enforce); + if (ctx->op == IPE_OP_INVALID) { rcu_read_unlock(); action = pol->parsed->global_default_action; @@ -167,9 +172,12 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) ipe_audit_match(ctx, match_type, action, rule); if (action == IPE_ACTION_DENY) - return -EACCES; + rc = -EACCES; + + if (!enforcing) + rc = 0; - return 0; + return rc; } /** @@ -198,3 +206,5 @@ void ipe_invalidate_pinned_sb(const struct super_block *mnt_sb) module_param(success_audit, bool, 0400); MODULE_PARM_DESC(success_audit, "Start IPE with success auditing enabled"); +module_param(enforce, bool, 0400); +MODULE_PARM_DESC(enforce, "Start IPE in enforce or permissive mode"); diff --git a/security/ipe/eval.h b/security/ipe/eval.h index 5473f712566c..3f7f71452618 100644 --- a/security/ipe/eval.h +++ b/security/ipe/eval.h @@ -15,6 +15,7 @@ extern struct ipe_policy __rcu *ipe_active_policy; extern bool success_audit; +extern bool enforce; struct ipe_eval_ctx { enum ipe_op_type op; diff --git a/security/ipe/fs.c b/security/ipe/fs.c index dda7a5afc60c..0a1838432bd0 100644 --- a/security/ipe/fs.c +++ b/security/ipe/fs.c @@ -16,6 +16,7 @@ static struct dentry *np __ro_after_init; static struct dentry *root __ro_after_init; struct dentry *policy_root __ro_after_init; static struct dentry *audit_node __ro_after_init; +static struct dentry *enforce_node __ro_after_init; /** * setaudit - Write handler for the securityfs node, "ipe/success_audit" @@ -67,6 +68,60 @@ static ssize_t getaudit(struct file *f, char __user *data, return simple_read_from_buffer(data, len, offset, result, 1); } +/** + * setenforce - Write handler for the securityfs node, "ipe/enforce" + * @f: Supplies a file structure representing the securityfs node. + * @data: Supplies a buffer passed to the write syscall. + * @len: Supplies the length of @data. + * @offset: unused. + * + * Return: + * * >0 - Success, Length of buffer written + * * <0 - Error + */ +static ssize_t setenforce(struct file *f, const char __user *data, + size_t len, loff_t *offset) +{ + int rc = 0; + bool new_value, old_value; + + if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN)) + return -EPERM; + + old_value = READ_ONCE(enforce); + rc = kstrtobool_from_user(data, len, &new_value); + if (rc) + return rc; + + if (new_value != old_value) { + ipe_audit_enforce(new_value, old_value); + WRITE_ONCE(enforce, new_value); + } + + return len; +} + +/** + * getenforce - Read handler for the securityfs node, "ipe/enforce" + * @f: Supplies a file structure representing the securityfs node. + * @data: Supplies a buffer passed to the read syscall. + * @len: Supplies the length of @data. + * @offset: unused. + * + * Return: + * * >0 - Success, Length of buffer written + * * <0 - Error + */ +static ssize_t getenforce(struct file *f, char __user *data, + size_t len, loff_t *offset) +{ + const char *result; + + result = ((READ_ONCE(enforce)) ? "1" : "0"); + + return simple_read_from_buffer(data, len, offset, result, 1); +} + /** * new_policy - Write handler for the securityfs node, "ipe/new_policy". * @f: Supplies a file structure representing the securityfs node. @@ -120,6 +175,11 @@ static const struct file_operations audit_fops = { .read = getaudit, }; +static const struct file_operations enforce_fops = { + .write = setenforce, + .read = getenforce, +}; + /** * ipe_init_securityfs - Initialize IPE's securityfs tree at fsinit. * @@ -147,6 +207,13 @@ static int __init ipe_init_securityfs(void) goto err; } + enforce_node = securityfs_create_file("enforce", 0600, root, NULL, + &enforce_fops); + if (IS_ERR(enforce_node)) { + rc = PTR_ERR(enforce_node); + goto err; + } + policy_root = securityfs_create_dir("policies", root); if (IS_ERR(policy_root)) { rc = PTR_ERR(policy_root); @@ -163,6 +230,7 @@ static int __init ipe_init_securityfs(void) err: securityfs_remove(np); securityfs_remove(policy_root); + securityfs_remove(enforce_node); securityfs_remove(audit_node); securityfs_remove(root); return rc;