From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.hallyn.com (mail.hallyn.com [178.63.66.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3078E44C68; Sat, 10 Aug 2024 20:05:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.63.66.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723320331; cv=none; b=PDwpMA9SpFyD48hnc7qOAxUxQ+qoCub490PFMZjWc1tXhXcp/cVuRKbnCoc0Kj9wvg4w3vqe05unoLtauqDeKZ3OhOmSgEbvkJorIhSlUiKmVK9w+3szNlSWpSawD2vICCRMgR69qp8cZtaCZDS/qgJnhbK5UTr2F7Aru8zvZdQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723320331; c=relaxed/simple; bh=V8k+LowYYOyKVujwCvCYLKZqEzPBWcRIa/WNWwRJxt4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AXZlOlabBHE6PIlja5Z+LrOXDH7Ck5mZV5M5PyIAchsGXmMJ9RXAI851JNPUlFvGlfoAumhfzACozZK8XMwHX4L1O5LoxeMrtz3RvaoC1vQgd0Qmpc/6Vlh729FHRaEGnXOz2mUC/ElI8paiHLfgRKqZlx67UXJ8UkkzTPg1rrk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hallyn.com; spf=pass smtp.mailfrom=mail.hallyn.com; arc=none smtp.client-ip=178.63.66.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hallyn.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mail.hallyn.com Received: by mail.hallyn.com (Postfix, from userid 1001) id 4E34950; Sat, 10 Aug 2024 15:05:26 -0500 (CDT) Date: Sat, 10 Aug 2024 15:05:26 -0500 From: "Serge E. Hallyn" To: Fan Wu Cc: 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, mpatocka@redhat.com, eparis@redhat.com, paul@paul-moore.com, 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 Subject: Re: [PATCH v20 03/20] ipe: add evaluation loop Message-ID: <20240810200526.GA40028@mail.hallyn.com> References: <1722665314-21156-1-git-send-email-wufan@linux.microsoft.com> <1722665314-21156-4-git-send-email-wufan@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1722665314-21156-4-git-send-email-wufan@linux.microsoft.com> On Fri, Aug 02, 2024 at 11:08:17PM -0700, Fan Wu wrote: > From: Deven Bowers > > Introduce a core evaluation function in IPE that will be triggered by > various security hooks (e.g., mmap, bprm_check, kexec). This function > systematically assesses actions against the defined IPE policy, by > iterating over rules specific to the action being taken. This critical > addition enables IPE to enforce its security policies effectively, > ensuring that actions intercepted by these hooks are scrutinized for policy > compliance before they are allowed to proceed. > > Signed-off-by: Deven Bowers > Signed-off-by: Fan Wu (started at this longer than I care to admit) Reviewed-by: Serge Hallyn > > --- > 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 > > v16: > + No changes > > v17: > + Add years to license header > + Fix code and documentation style issues > > v18: > + No changes > > v19: > + No changes > > v20: > + No changes > --- > security/ipe/Makefile | 1 + > security/ipe/eval.c | 102 ++++++++++++++++++++++++++++++++++++++++++ > security/ipe/eval.h | 24 ++++++++++ > 3 files changed, 127 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 3093de1afd3e..4cc17eb92060 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..f6a681ca49f6 > --- /dev/null > +++ b/security/ipe/eval.c > @@ -0,0 +1,102 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2020-2024 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 rule property. > + * @ctx: Supplies a pointer to the context to be evaluated. > + * @p: Supplies a pointer to the property to be evaluated. > + * > + * This is a placeholder. The actual function will be introduced in the > + * latter commits. > + * > + * 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 evaluations happen against the IPE policy. > + * > + * Return: > + * * %0 - Success > + * * %-EACCES - @ctx did not pass evaluation > + */ > +int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) > +{ > + const struct ipe_op_table *rules = NULL; > + const struct ipe_rule *rule = NULL; > + struct ipe_policy *pol = NULL; > + struct ipe_prop *prop = NULL; > + enum ipe_action_type action; > + bool match = false; > + > + 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..b137f2107852 > --- /dev/null > +++ b/security/ipe/eval.h > @@ -0,0 +1,24 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) 2020-2024 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 */ > -- > 2.44.0