From nobody Mon Feb 9 23:43:05 2026 Received: from smtp-8fab.mail.infomaniak.ch (smtp-8fab.mail.infomaniak.ch [83.166.143.171]) (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 A87C5215181 for ; Sat, 8 Mar 2025 18:44:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=83.166.143.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741459500; cv=none; b=cnl64uQMaJ9/WwA1JAJLMgEXi2nkuy5tLPj0MQGglWLPlbwmKPTCVIsPqPpgMrzlnENsnSvZixGDhoyE6wojAXcFD07ulQ/8V27h2Ufj8b9thb3zXkvjy571d2ZO9tZP6rEJ37/FuQm/xnK8Hq/5ObVFTMkMydJ3Ra9TR4ZjNDk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741459500; c=relaxed/simple; bh=cpV6J7vFv8QlFZY9S6XFDG63kp4XExRkTYYnDCOW2Zg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=PTrpOdMy7aQCR5Th5xGEdB0kvxd/WS22eAF4mfbFBIuCpg0ADFPEb89qIa/QpMPM9/XLcXC/Reg7nB9XMorDJ43Ter4B2PotdA4Ev1s3xpiRN3vAnjkWM+KnJD9hpEfVT3C3+GoD4Boy3iQnJpJjl7EKT7p4ckhI3QfuZiGpQTE= 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=Ts51/geC; arc=none smtp.client-ip=83.166.143.171 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="Ts51/geC" Received: from smtp-4-0000.mail.infomaniak.ch (smtp-4-0000.mail.infomaniak.ch [10.7.10.107]) by smtp-4-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4Z9Bsg6DYgzS6w; Sat, 8 Mar 2025 19:44:55 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1741459495; bh=v7zxGlR9p2Vk6aOhQ+9hHdnseZZyVA7sQx36u2Dx7Fs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ts51/geCAI90y4KlErY52fZVtW5rS8byJpifQ7ixm9wf9grvtX2gUw3HcgdeM4EsU UVXTvKtmLIecvxi2aJIec4JfZU9UfwtFy2xSz2YbKqKb9cFcaASrpCmgYOXF1yD1hP E7XTo20BVmZYCMDAVgIv2JwuEBWWsRc/OCfSAP7E= Received: from unknown by smtp-4-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4Z9Bsf6tT7zGbL; Sat, 8 Mar 2025 19:44:54 +0100 (CET) From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= To: Eric Paris , Paul Moore , =?UTF-8?q?G=C3=BCnther=20Noack?= , "Serge E . Hallyn" Cc: =?UTF-8?q?Micka=C3=ABl=20Sala=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 , 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 v6 15/26] landlock: Log scoped denials Date: Sat, 8 Mar 2025 19:44:11 +0100 Message-ID: <20250308184422.2159360-16-mic@digikod.net> In-Reply-To: <20250308184422.2159360-1-mic@digikod.net> References: <20250308184422.2159360-1-mic@digikod.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Infomaniak-Routing: alpha Add audit support for unix_stream_connect, unix_may_send, task_kill, and file_send_sigiotask hooks. The related blockers are: - scope.abstract_unix_socket - scope.signal Audit event sample for abstract unix socket: type=3DLANDLOCK_DENY msg=3Daudit(1729738800.268:30): domain=3D195ba459b b= lockers=3Dscope.abstract_unix_socket path=3D00666F6F Audit event sample for signal: type=3DLANDLOCK_DENY msg=3Daudit(1729738800.291:31): domain=3D195ba459b b= lockers=3Dscope.signal opid=3D1 ocomm=3D"systemd" Refactor and simplify error handling in LSM hooks. Extend struct landlock_file_security with fown_layer and use it to log the blocking domain. The struct aligned size is still 16 bytes. Cc: G=C3=BCnther Noack Cc: Tahera Fahimi Signed-off-by: Micka=C3=ABl Sala=C3=BCn Link: https://lore.kernel.org/r/20250308184422.2159360-16-mic@digikod.net --- Changes since v5: - Move request declarations in the landlock_log_denial() calls to not impact allowed requests with audit, and return as soon as possible when access is allowed. - Store a fown_layer per file and use it to log the blocking domain. - Refactor and simplify error handling in LSM hooks. Changes since v4: - Rebase on top of the landlock_log_denial() and subject type changes. Changes since v3: - Cosmetic change to the "scope.*" blocker names. - Extend commit message. Changes since v1: - New patch. --- security/landlock/audit.c | 8 ++++ security/landlock/audit.h | 2 + security/landlock/fs.c | 7 +++- security/landlock/fs.h | 14 +++++++ security/landlock/task.c | 79 +++++++++++++++++++++++++++++++-------- 5 files changed, 92 insertions(+), 18 deletions(-) diff --git a/security/landlock/audit.c b/security/landlock/audit.c index 6c34758b9ff2..d0eafb946f31 100644 --- a/security/landlock/audit.c +++ b/security/landlock/audit.c @@ -71,6 +71,14 @@ get_blocker(const enum landlock_request_type type, if (WARN_ON_ONCE(access_bit >=3D ARRAY_SIZE(net_access_strings))) return "unknown"; return net_access_strings[access_bit]; + + case LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET: + WARN_ON_ONCE(access_bit !=3D -1); + return "scope.abstract_unix_socket"; + + case LANDLOCK_REQUEST_SCOPE_SIGNAL: + WARN_ON_ONCE(access_bit !=3D -1); + return "scope.signal"; } =20 WARN_ON_ONCE(1); diff --git a/security/landlock/audit.h b/security/landlock/audit.h index eeff2c5bfa4f..aaf21b31baa8 100644 --- a/security/landlock/audit.h +++ b/security/landlock/audit.h @@ -20,6 +20,8 @@ enum landlock_request_type { LANDLOCK_REQUEST_FS_CHANGE_LAYOUT, LANDLOCK_REQUEST_FS_ACCESS, LANDLOCK_REQUEST_NET_ACCESS, + LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET, + LANDLOCK_REQUEST_SCOPE_SIGNAL, }; =20 /* diff --git a/security/landlock/fs.c b/security/landlock/fs.c index 14f9c6d9903f..34f316031ecf 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -1798,6 +1798,7 @@ static void hook_file_set_fowner(struct file *file) const struct landlock_cred_security *new_subject; struct landlock_cred_security *fown_subject; struct landlock_ruleset *prev_dom; + size_t handle_layer; =20 /* * Lock already held by __f_setown(), see commit 26f204380a3c ("fs: Fix @@ -1807,15 +1808,17 @@ static void hook_file_set_fowner(struct file *file) =20 fown_subject =3D &landlock_file(file)->fown_subject; prev_dom =3D fown_subject->domain; - new_subject =3D landlock_get_applicable_subject(current_cred(), - signal_scope, NULL); + new_subject =3D landlock_get_applicable_subject( + current_cred(), signal_scope, &handle_layer); if (new_subject) { landlock_get_ruleset(new_subject->domain); *fown_subject =3D *new_subject; + landlock_file(file)->fown_layer =3D handle_layer; } else { static const struct landlock_cred_security empty =3D {}; =20 *fown_subject =3D empty; + landlock_file(file)->fown_layer =3D 0; } =20 /* Called in an RCU read-side critical section. */ diff --git a/security/landlock/fs.h b/security/landlock/fs.h index 3a09ba985b74..a2a2014d68ae 100644 --- a/security/landlock/fs.h +++ b/security/landlock/fs.h @@ -9,6 +9,7 @@ #ifndef _SECURITY_LANDLOCK_FS_H #define _SECURITY_LANDLOCK_FS_H =20 +#include #include #include #include @@ -61,6 +62,11 @@ struct landlock_file_security { * _LANDLOCK_ACCESS_FS_OPTIONAL). */ deny_masks_t deny_masks; + /** + * @fown_layer: Layer level of @fown_subject->domain with + * LANDLOCK_SCOPE_SIGNAL. + */ + u8 fown_layer; #endif /* CONFIG_AUDIT */ =20 /** @@ -73,6 +79,14 @@ struct landlock_file_security { struct landlock_cred_security fown_subject; }; =20 +#ifdef CONFIG_AUDIT + +/* Makes sure all layers can be identified. */ +static_assert((typeof_member(struct landlock_file_security, fown_layer))~0= >=3D + LANDLOCK_MAX_NUM_LAYERS); + +#endif /* CONFIG_AUDIT */ + /** * struct landlock_superblock_security - Superblock security blob * diff --git a/security/landlock/task.c b/security/landlock/task.c index e8a0b4ead381..f6359cf4c11b 100644 --- a/security/landlock/task.c +++ b/security/landlock/task.c @@ -264,26 +264,41 @@ static int hook_unix_stream_connect(struct sock *cons= t sock, struct sock *const other, struct sock *const newsk) { + size_t handle_layer; const struct landlock_cred_security *const subject =3D landlock_get_applicable_subject(current_cred(), unix_scope, - NULL); + &handle_layer); =20 /* Quick return for non-landlocked tasks. */ if (!subject) return 0; =20 - if (is_abstract_socket(other) && sock_is_scoped(other, subject->domain)) - return -EPERM; + if (!is_abstract_socket(other)) + return 0; + + if (!sock_is_scoped(other, subject->domain)) + return 0; =20 - return 0; + landlock_log_denial(subject, &(struct landlock_request) { + .type =3D LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET, + .audit =3D { + .type =3D LSM_AUDIT_DATA_NET, + .u.net =3D &(struct lsm_network_audit) { + .sk =3D other, + }, + }, + .layer_plus_one =3D handle_layer + 1, + }); + return -EPERM; } =20 static int hook_unix_may_send(struct socket *const sock, struct socket *const other) { + size_t handle_layer; const struct landlock_cred_security *const subject =3D landlock_get_applicable_subject(current_cred(), unix_scope, - NULL); + &handle_layer); =20 if (!subject) return 0; @@ -295,11 +310,23 @@ static int hook_unix_may_send(struct socket *const so= ck, if (unix_peer(sock->sk) =3D=3D other->sk) return 0; =20 - if (is_abstract_socket(other->sk) && - sock_is_scoped(other->sk, subject->domain)) - return -EPERM; + if (!is_abstract_socket(other->sk)) + return 0; + + if (!sock_is_scoped(other->sk, subject->domain)) + return 0; =20 - return 0; + landlock_log_denial(subject, &(struct landlock_request) { + .type =3D LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET, + .audit =3D { + .type =3D LSM_AUDIT_DATA_NET, + .u.net =3D &(struct lsm_network_audit) { + .sk =3D other->sk, + }, + }, + .layer_plus_one =3D handle_layer + 1, + }); + return -EPERM; } =20 static const struct access_masks signal_scope =3D { @@ -311,13 +338,15 @@ static int hook_task_kill(struct task_struct *const p, const struct cred *cred) { bool is_scoped; + size_t handle_layer; const struct landlock_cred_security *subject; =20 if (!cred) /* Not dealing with USB IO. */ cred =3D current_cred(); =20 - subject =3D landlock_get_applicable_subject(cred, signal_scope, NULL); + subject =3D landlock_get_applicable_subject(cred, signal_scope, + &handle_layer); =20 /* Quick return for non-landlocked tasks. */ if (!subject) @@ -329,10 +358,19 @@ static int hook_task_kill(struct task_struct *const p, landlock_get_task_domain(p), signal_scope.scope); } - if (is_scoped) - return -EPERM; =20 - return 0; + if (!is_scoped) + return 0; + + landlock_log_denial(subject, &(struct landlock_request) { + .type =3D LANDLOCK_REQUEST_SCOPE_SIGNAL, + .audit =3D { + .type =3D LSM_AUDIT_DATA_TASK, + .u.tsk =3D p, + }, + .layer_plus_one =3D handle_layer + 1, + }); + return -EPERM; } =20 static int hook_file_send_sigiotask(struct task_struct *tsk, @@ -361,10 +399,19 @@ static int hook_file_send_sigiotask(struct task_struc= t *tsk, landlock_get_task_domain(tsk), signal_scope.scope); } - if (is_scoped) - return -EPERM; =20 - return 0; + if (!is_scoped) + return 0; + + landlock_log_denial(subject, &(struct landlock_request) { + .type =3D LANDLOCK_REQUEST_SCOPE_SIGNAL, + .audit =3D { + .type =3D LSM_AUDIT_DATA_TASK, + .u.tsk =3D tsk, + }, + .layer_plus_one =3D landlock_file(fown->file)->fown_layer + 1, + }); + return -EPERM; } =20 static struct security_hook_list landlock_hooks[] __ro_after_init =3D { --=20 2.48.1