From patchwork Sat Mar 16 03:35:33 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fan Wu X-Patchwork-Id: 13594246 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CA200468E; Sat, 16 Mar 2024 03:35:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710560155; cv=none; b=kDsUQXBWcY+GyuBJ9mCXYDMGwwH/dfkODdKdIgynQ86l7VKwlFz21nWZUz9csg+7VcObbyhjJ4hIVQbppErcHNe3JWP/X21OfVgMwX4NNHaocv7MXLdcm0Izr/hSTXreX/nOUeoCtbBC1FPjF9uCpx7dEs9uVDBLmZ9/taA9GtI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710560155; c=relaxed/simple; bh=0HYMmXFQiUYdpor45HdVAZ7TnZ3SPpBu02cqhIfQcXY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=o0l2k3fIlYCMRowwl6TXZ0WK7f+Gy7ak8BqFULsOsIJVUt5+zUwY2ecQF1pLfQsO+Lj/r7CGcSPx4G7yJ2GMVXwKNjlvncVbNOrE/xgWepn98gqAYJI4Rb9SM3nuzafJecq1QUJfyOqHZtLOGXDwL38zRRa51LeL7faVFKZdpiw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=l0Ezzo1w; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="l0Ezzo1w" Received: by linux.microsoft.com (Postfix, from userid 1052) id 5270F20B74C5; Fri, 15 Mar 2024 20:35:53 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 5270F20B74C5 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1710560153; bh=lNvLTgbnDJF5Hx/jhgStjSzrLIJ4pmc6ggvHSNQSq0k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l0Ezzo1wIEWC0z7JvhKhANr1UKjij2613CmDB8A3oi9wI+S2mT1U25NjlfPQ1UlNz 49xKzVY43HhsiW+ipArVpSnayU1Ft8kvHLHLWCmhHQ4JCXX4DqBeuqo6asGfdMDCEf OkadjdPUcaoDi2gTyCy8P6w8qhrgIunGsFjqA0gk= 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, fsverity@lists.linux.dev, linux-block@vger.kernel.org, dm-devel@lists.linux.dev, audit@vger.kernel.org, linux-kernel@vger.kernel.org, Deven Bowers , Fan Wu Subject: [RFC PATCH v15 03/21] ipe: add evaluation loop Date: Fri, 15 Mar 2024 20:35:33 -0700 Message-Id: <1710560151-28904-4-git-send-email-wufan@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1710560151-28904-1-git-send-email-wufan@linux.microsoft.com> References: <1710560151-28904-1-git-send-email-wufan@linux.microsoft.com> Precedence: bulk X-Mailing-List: fsverity@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Deven Bowers IPE must have a centralized function to evaluate incoming callers against IPE's policy. This iteration of the policy for against the rules for that specific caller is known as the evaluation loop. 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. v8: + Remove ipe_hook enumeration; hooks can be correlated via syscall record. v9: + Remove ipe_context related code and simplify the evaluation loop. v10: + Split eval part and boot_verified part v11: + Fix code style issues v12: + Correct an rcu_read_unlock usage + Add a WARN to unknown op during evaluation v13: + No changes v14: + No changes v15: + No changes --- security/ipe/Makefile | 1 + security/ipe/eval.c | 100 ++++++++++++++++++++++++++++++++++++++++++ security/ipe/eval.h | 24 ++++++++++ 3 files changed, 125 insertions(+) create mode 100644 security/ipe/eval.c create mode 100644 security/ipe/eval.h diff --git a/security/ipe/Makefile b/security/ipe/Makefile index c09aec4904f2..57fe922cf1fc 100644 --- a/security/ipe/Makefile +++ b/security/ipe/Makefile @@ -6,6 +6,7 @@ # obj-$(CONFIG_SECURITY_IPE) += \ + eval.o \ ipe.o \ policy.o \ policy_parser.o \ diff --git a/security/ipe/eval.c b/security/ipe/eval.c new file mode 100644 index 000000000000..af56815ed0fa --- /dev/null +++ b/security/ipe/eval.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ + +#include +#include +#include +#include +#include +#include + +#include "ipe.h" +#include "eval.h" +#include "policy.h" + +struct ipe_policy __rcu *ipe_active_policy; + +/** + * evaluate_property - Analyze @ctx against a property. + * @ctx: Supplies a pointer to the context to be evaluated. + * @p: Supplies a pointer to the property to be evaluated. + * + * Return: + * * true - The current @ctx match the @p + * * false - The current @ctx doesn't match the @p + */ +static bool evaluate_property(const struct ipe_eval_ctx *const ctx, + struct ipe_prop *p) +{ + return false; +} + +/** + * ipe_evaluate_event - Analyze @ctx against the current active policy. + * @ctx: Supplies a pointer to the context to be evaluated. + * + * This is the loop where all policy evaluation happens against IPE policy. + * + * Return: + * * 0 - OK + * * -EACCES - @ctx did not pass evaluation. + * * !0 - Error + */ +int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) +{ + bool match = false; + enum ipe_action_type action; + struct ipe_policy *pol = NULL; + const struct ipe_rule *rule = NULL; + const struct ipe_op_table *rules = NULL; + struct ipe_prop *prop = NULL; + + rcu_read_lock(); + + pol = rcu_dereference(ipe_active_policy); + if (!pol) { + rcu_read_unlock(); + return 0; + } + + if (ctx->op == IPE_OP_INVALID) { + if (pol->parsed->global_default_action == IPE_ACTION_DENY) { + rcu_read_unlock(); + return -EACCES; + } + if (pol->parsed->global_default_action == IPE_ACTION_INVALID) + WARN(1, "no default rule set for unknown op, ALLOW it"); + rcu_read_unlock(); + return 0; + } + + rules = &pol->parsed->rules[ctx->op]; + + list_for_each_entry(rule, &rules->rules, next) { + match = true; + + list_for_each_entry(prop, &rule->props, next) { + match = evaluate_property(ctx, prop); + if (!match) + break; + } + + if (match) + break; + } + + if (match) + action = rule->action; + else if (rules->default_action != IPE_ACTION_INVALID) + action = rules->default_action; + else + action = pol->parsed->global_default_action; + + rcu_read_unlock(); + if (action == IPE_ACTION_DENY) + return -EACCES; + + return 0; +} diff --git a/security/ipe/eval.h b/security/ipe/eval.h new file mode 100644 index 000000000000..6b434515968f --- /dev/null +++ b/security/ipe/eval.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) Microsoft Corporation. All rights reserved. + */ + +#ifndef _IPE_EVAL_H +#define _IPE_EVAL_H + +#include +#include + +#include "policy.h" + +extern struct ipe_policy __rcu *ipe_active_policy; + +struct ipe_eval_ctx { + enum ipe_op_type op; + + const struct file *file; +}; + +int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx); + +#endif /* _IPE_EVAL_H */