From patchwork Thu Mar 20 19:06:57 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= X-Patchwork-Id: 14024447 X-Patchwork-Delegate: paul@paul-moore.com Received: from smtp-8fa8.mail.infomaniak.ch (smtp-8fa8.mail.infomaniak.ch [83.166.143.168]) (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 AD432227EB1 for ; Thu, 20 Mar 2025 19:07:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=83.166.143.168 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742497661; cv=none; b=cvFi3OwbZwmH3oPpy21dgpo6b5X2+QR858pwHIJ3Ymhd7Qni2hMqxzCGyUw8h4O0KyNAx27dCv8ZqCmQMdQPv9ycbozU1FtQobkTOXisH7tILBudgfCPOTPnT5OQeWWV1UVuZcZMhtnawFecs3/m6i+yTN58P3xPsyexfbZKzQs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742497661; c=relaxed/simple; bh=TS7HZ1tKjXQnVztsV6C3ej4LWIVlk+jcfBJsAi/DHNE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Mmp5nG+RHkZcE7GyqsSM7acA5EEw3SlMrKVqugqU9TeLgGkKJCvAgXJS/2pPKSPVEixStHmhRLD+PeY50769iRXksPQoIctZAiZDyrp8iPrUsxuznTGBcBmSuYqmxhCpWHF+XTfs8cA2HGKEl3ufdsiCnjjCe7d5qEchm85o2Qc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net; spf=pass smtp.mailfrom=digikod.net; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b=UGaKNES8; arc=none smtp.client-ip=83.166.143.168 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=digikod.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b="UGaKNES8" Received: from smtp-3-0001.mail.infomaniak.ch (smtp-3-0001.mail.infomaniak.ch [10.4.36.108]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4ZJZpJ6gqNznK; Thu, 20 Mar 2025 20:07:36 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1742497656; bh=Iln42cUtkMn9/d1YlfuMQNlo3p0jfKXK7NGjwJaBbRE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UGaKNES8SylO8RlSkJ12HpR/gWSiAHZBzLgEGTvBLBrQCmSh8Mu/s/5E6hdmvz5MA h1w/65fflI1P6ArcUU/hFKB1cYyY42mwU5AblTckejO6RT1HGxDtF7zWzIKUU3+geh cIJxjFzHe/YgnYtMqY3hb1r20ix5d8sDRJBD6PTA= Received: from unknown by smtp-3-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4ZJZpJ1F4WzCsL; Thu, 20 Mar 2025 20:07:36 +0100 (CET) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: Eric Paris , Paul Moore , =?utf-8?q?G=C3=BCnther_Noack?= , "Serge E . Hallyn" Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Ben Scarlato , Casey Schaufler , Charles Zaffery , Daniel Burgener , Francis Laniel , James Morris , Jann Horn , Jeff Xu , Jorge Lucangeli Obes , Kees Cook , Konstantin Meskhidze , Matt Bobrowski , Matthieu Buffet , Mikhail Ivanov , Phil Sutter , Praveen K Paladugu , Robert Salvet , Shervin Oloumi , Song Liu , Tahera Fahimi , Tingmao Wang , Tyler Hicks , audit@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v7 08/28] landlock: Identify domain execution crossing Date: Thu, 20 Mar 2025 20:06:57 +0100 Message-ID: <20250320190717.2287696-9-mic@digikod.net> In-Reply-To: <20250320190717.2287696-1-mic@digikod.net> References: <20250320190717.2287696-1-mic@digikod.net> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Infomaniak-Routing: alpha Extend struct landlock_cred_security with a domain_exec bitmask to identify which Landlock domain were created by the current task's bprm. The whole bitmask is reset on each execve(2) call. Cc: Günther Noack Cc: Paul Moore Signed-off-by: Mickaël Salaün --- Changes since v5: - Add documentation and pack struct landlock_cred_security to minimize struct landlock_file_security. Changes since v4: - New patch. --- security/landlock/cred.c | 26 ++++++++++++++++++++++---- security/landlock/cred.h | 32 +++++++++++++++++++++++++++++++- security/landlock/syscalls.c | 5 +++++ 3 files changed, 58 insertions(+), 5 deletions(-) diff --git a/security/landlock/cred.c b/security/landlock/cred.c index db9fe7d906ba..a22756fe3b71 100644 --- a/security/landlock/cred.c +++ b/security/landlock/cred.c @@ -4,8 +4,10 @@ * * Copyright © 2017-2020 Mickaël Salaün * Copyright © 2018-2020 ANSSI + * Copyright © 2025 Microsoft Corporation */ +#include #include #include @@ -17,11 +19,12 @@ static void hook_cred_transfer(struct cred *const new, const struct cred *const old) { - struct landlock_ruleset *const old_dom = landlock_cred(old)->domain; + const struct landlock_cred_security *const old_llcred = + landlock_cred(old); - if (old_dom) { - landlock_get_ruleset(old_dom); - landlock_cred(new)->domain = old_dom; + if (old_llcred->domain) { + landlock_get_ruleset(old_llcred->domain); + *landlock_cred(new) = *old_llcred; } } @@ -40,10 +43,25 @@ static void hook_cred_free(struct cred *const cred) landlock_put_ruleset_deferred(dom); } +#ifdef CONFIG_AUDIT + +static int hook_bprm_creds_for_exec(struct linux_binprm *const bprm) +{ + /* Resets for each execution. */ + landlock_cred(bprm->cred)->domain_exec = 0; + return 0; +} + +#endif /* CONFIG_AUDIT */ + static struct security_hook_list landlock_hooks[] __ro_after_init = { LSM_HOOK_INIT(cred_prepare, hook_cred_prepare), LSM_HOOK_INIT(cred_transfer, hook_cred_transfer), LSM_HOOK_INIT(cred_free, hook_cred_free), + +#ifdef CONFIG_AUDIT + LSM_HOOK_INIT(bprm_creds_for_exec, hook_bprm_creds_for_exec), +#endif /* CONFIG_AUDIT */ }; __init void landlock_add_cred_hooks(void) diff --git a/security/landlock/cred.h b/security/landlock/cred.h index eb691130dd67..3bf18551d7b8 100644 --- a/security/landlock/cred.h +++ b/security/landlock/cred.h @@ -10,17 +10,47 @@ #ifndef _SECURITY_LANDLOCK_CRED_H #define _SECURITY_LANDLOCK_CRED_H +#include #include #include #include #include "access.h" +#include "limits.h" #include "ruleset.h" #include "setup.h" +/** + * struct landlock_cred_security - Credential security blob + * + * This structure is packed to minimize the size of struct + * landlock_file_security. However, it is always aligned in the LSM cred blob, + * see lsm_set_blob_size(). + */ struct landlock_cred_security { + /** + * @domain: Immutable ruleset enforced on a task. + */ struct landlock_ruleset *domain; -}; + +#ifdef CONFIG_AUDIT + /** + * @domain_exec: Bitmask identifying the domain layers that were enforced by + * the current task's executed file (i.e. no new execve(2) since + * landlock_restrict_self(2)). + */ + u16 domain_exec; +#endif /* CONFIG_AUDIT */ +} __packed; + +#ifdef CONFIG_AUDIT + +/* Makes sure all layer executions can be stored. */ +static_assert(BITS_PER_TYPE(typeof_member(struct landlock_cred_security, + domain_exec)) >= + LANDLOCK_MAX_NUM_LAYERS); + +#endif /* CONFIG_AUDIT */ static inline struct landlock_cred_security * landlock_cred(const struct cred *cred) diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index cf9e0483e542..b7b268f43a3b 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -510,5 +510,10 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32, /* Replaces the old (prepared) domain. */ landlock_put_ruleset(new_llcred->domain); new_llcred->domain = new_dom; + +#ifdef CONFIG_AUDIT + new_llcred->domain_exec |= 1 << (new_dom->num_layers - 1); +#endif /* CONFIG_AUDIT */ + return commit_creds(new_cred); }