From patchwork Fri Nov 22 14:33:41 2024 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: 13883239 Received: from smtp-1908.mail.infomaniak.ch (smtp-1908.mail.infomaniak.ch [185.125.25.8]) (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 81C491B0F0C for ; Fri, 22 Nov 2024 14:34:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.125.25.8 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732286062; cv=none; b=YPATH8tR8r9mrLAO7JjntcGT9AwjYJjMLxGXDiSprLPCoSrraFMlFJCBMomLH0iERcX3s+VyDDFPnEWZL4g3C6l+gOqrWesw9jsKqjrTX7za2zq9HlWFEhkWHOJ9mWG+UVADm94ecT/0ajqXVT5v5paLOK6e7lazsxD/RXqGkHY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732286062; c=relaxed/simple; bh=6kd3USl/v5quMElIHNSewxBHZwwNtlMc/QPwm7gFPjs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=e+mxC4GZVJ1j1VDEgJT7svklQeO1DfJB1BEAWc4bDOpyqVtf3cYAXuXtF/8dtm/s4eEMUPO5mCzRDZqjOxHN/M5h8jewize25izyYzi1hhcACId+SqR3HMUqHFe3xysfOf788ZWPqKxsaPoF8BVx7KM5EJ3jX3B/030PzMvY3eY= 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=BIc+0LYp; arc=none smtp.client-ip=185.125.25.8 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="BIc+0LYp" Received: from smtp-3-0000.mail.infomaniak.ch (unknown [IPv6:2001:1600:4:17::246b]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4XvyKP6cq8zlSd; Fri, 22 Nov 2024 15:34:17 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1732286057; bh=kk+ZrO9KuElri+1LTWSQtEzwM18pB5uBoFHaUi66ZKc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BIc+0LYp4Mg9RSnjDBBFqErOczP0XtRa5aiELSN41ta+AimREo3E7GYhJXW3VGAK3 5bfaBH64hFbfaRrzOHD4yg7EXgXOgSggsKxqvuGPyRf9uZF3Gnqv0kiGXQriZkw1Lx Kdm0DH1FbvfOn74Y18TQ3QzzQMRYRQOqp2GgCucw= Received: from unknown by smtp-3-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4XvyKN6gbTzmHf; Fri, 22 Nov 2024 15:34:16 +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 , 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 , audit@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v3 11/23] landlock: Log mount-related denials Date: Fri, 22 Nov 2024 15:33:41 +0100 Message-ID: <20241122143353.59367-12-mic@digikod.net> In-Reply-To: <20241122143353.59367-1-mic@digikod.net> References: <20241122143353.59367-1-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 Add audit support for sb_mount, move_mount, sb_umount, sb_remount, and sb_pivot_root hooks. Add and use a new landlock_match_layer_level() helper. Audit event sample: type=LL_DENY [...]: domain=195ba459b blockers=fs_change_layout name="/" dev="tmpfs" ino=1 Cc: Günther Noack Signed-off-by: Mickaël Salaün Link: https://lore.kernel.org/r/20241122143353.59367-12-mic@digikod.net --- Changes since v2: - Log the domain that denied the action because not all layers block FS layout changes. - Fix landlock_match_layer_level(). Changes since v1: - Rebased on the TCP patch series. - Don't log missing permissions, only domain layer, and then remove the permission word (suggested by Günther) --- security/landlock/audit.c | 3 ++ security/landlock/audit.h | 1 + security/landlock/fs.c | 64 ++++++++++++++++++++++++++++++++++--- security/landlock/ruleset.h | 31 ++++++++++++++++++ 4 files changed, 94 insertions(+), 5 deletions(-) diff --git a/security/landlock/audit.c b/security/landlock/audit.c index 2d0a96797dd4..a07b210ca524 100644 --- a/security/landlock/audit.c +++ b/security/landlock/audit.c @@ -21,6 +21,9 @@ static const char *get_blocker(const enum landlock_request_type type) switch (type) { case LANDLOCK_REQUEST_PTRACE: return "ptrace"; + + case LANDLOCK_REQUEST_FS_CHANGE_LAYOUT: + return "fs_change_layout"; } WARN_ON_ONCE(1); diff --git a/security/landlock/audit.h b/security/landlock/audit.h index 7a1b1652f21b..6f5ad04b83c2 100644 --- a/security/landlock/audit.h +++ b/security/landlock/audit.h @@ -15,6 +15,7 @@ enum landlock_request_type { LANDLOCK_REQUEST_PTRACE = 1, + LANDLOCK_REQUEST_FS_CHANGE_LAYOUT, }; /* diff --git a/security/landlock/fs.c b/security/landlock/fs.c index 9779170d9199..171012efb559 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -37,6 +38,7 @@ #include #include "access.h" +#include "audit.h" #include "common.h" #include "cred.h" #include "fs.h" @@ -1301,6 +1303,38 @@ static void hook_sb_delete(struct super_block *const sb) !atomic_long_read(&landlock_superblock(sb)->inode_refs)); } +static void +log_fs_change_layout_path(const struct landlock_ruleset *const domain, + const struct path *const path) +{ + const struct landlock_request request = { + .type = LANDLOCK_REQUEST_FS_CHANGE_LAYOUT, + .audit = { + .type = LSM_AUDIT_DATA_PATH, + .u.path = *path, + }, + .layer_plus_one = landlock_match_layer_level(domain, any_fs) + 1, + }; + + landlock_log_denial(domain, &request); +} + +static void +log_fs_change_layout_dentry(const struct landlock_ruleset *const domain, + struct dentry *const dentry) +{ + const struct landlock_request request = { + .type = LANDLOCK_REQUEST_FS_CHANGE_LAYOUT, + .audit = { + .type = LSM_AUDIT_DATA_DENTRY, + .u.dentry = dentry, + }, + .layer_plus_one = landlock_match_layer_level(domain, any_fs) + 1, + }; + + landlock_log_denial(domain, &request); +} + /* * Because a Landlock security policy is defined according to the filesystem * topology (i.e. the mount namespace), changing it may grant access to files @@ -1323,16 +1357,24 @@ static int hook_sb_mount(const char *const dev_name, const struct path *const path, const char *const type, const unsigned long flags, void *const data) { - if (!get_current_fs_domain()) + const struct landlock_ruleset *const dom = get_current_fs_domain(); + + if (!dom) return 0; + + log_fs_change_layout_path(dom, path); return -EPERM; } static int hook_move_mount(const struct path *const from_path, const struct path *const to_path) { - if (!get_current_fs_domain()) + const struct landlock_ruleset *const dom = get_current_fs_domain(); + + if (!dom) return 0; + + log_fs_change_layout_path(dom, to_path); return -EPERM; } @@ -1342,15 +1384,23 @@ static int hook_move_mount(const struct path *const from_path, */ static int hook_sb_umount(struct vfsmount *const mnt, const int flags) { - if (!get_current_fs_domain()) + const struct landlock_ruleset *const dom = get_current_fs_domain(); + + if (!dom) return 0; + + log_fs_change_layout_dentry(dom, mnt->mnt_root); return -EPERM; } static int hook_sb_remount(struct super_block *const sb, void *const mnt_opts) { - if (!get_current_fs_domain()) + const struct landlock_ruleset *const dom = get_current_fs_domain(); + + if (!dom) return 0; + + log_fs_change_layout_dentry(dom, sb->s_root); return -EPERM; } @@ -1365,8 +1415,12 @@ static int hook_sb_remount(struct super_block *const sb, void *const mnt_opts) static int hook_sb_pivotroot(const struct path *const old_path, const struct path *const new_path) { - if (!get_current_fs_domain()) + const struct landlock_ruleset *const dom = get_current_fs_domain(); + + if (!dom) return 0; + + log_fs_change_layout_path(dom, new_path); return -EPERM; } diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 73636f214aac..944126a92aec 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -268,6 +268,37 @@ landlock_get_applicable_domain(const struct landlock_ruleset *const domain, return NULL; } +/** + * landlock_match_layer_level - Return the layer level restricting @masks + * + * @domain: Landlock ruleset (used as a domain) + * @masks: access masks + * + * Returns: the number of the layer restricting/handling any right of @access, + * or return 0 (i.e. first layer) otherwise. + */ +static inline size_t +landlock_match_layer_level(const struct landlock_ruleset *const domain, + const struct access_masks masks) +{ + const union access_masks_all masks_all = { + .masks = masks, + }; + ssize_t layer_level; + + for (layer_level = domain->num_layers; layer_level >= 0; + layer_level--) { + union access_masks_all layer = { + .masks = domain->access_masks[layer_level], + }; + + if (masks_all.all & layer.all) + return layer_level; + } + + return 0; +} + static inline void landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset, const access_mask_t fs_access_mask,