From patchwork Tue Oct 22 16:10:04 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: 13845918 X-Patchwork-Delegate: paul@paul-moore.com Received: from smtp-42ad.mail.infomaniak.ch (smtp-42ad.mail.infomaniak.ch [84.16.66.173]) (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 436751B5808; Tue, 22 Oct 2024 16:10:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=84.16.66.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729613437; cv=none; b=HFMU7gBzWIEcmezIXD9PwSVrIitzAe+fxDqrFinibbYwZIpzIdY6vboJZSQdUFm8qIuqhm8B/uO7o5y3KXV96yy9lvVBJ5kHYq/vkpJK3HbhWZrFl9ulfRnG3e8fVqKA+ogMJRzthpy1GXcav30c3Z0Llc3M9eutCzX8ixpEC74= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729613437; c=relaxed/simple; bh=CbChgtXckXk3u1m3Yox0x6RBMdZITj8ROOX7Y3B0368=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=nWmkxH97UcyRNN6VcqvtkZIdw51mJTRefKRJgNfsZzPm9KVloNXaD/z5o+5lbBRNL7+663ZBjp8SwRi+UoxmZl9MsbXCUhIEiGlEDOdUU+K+a1rWqRdyoPBi7CbNQ3XtAXpOdGFqVqOb1sv1T0O93X+C6qApntwQmcPrCZkmZ5Y= 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=WQstIalo; arc=none smtp.client-ip=84.16.66.173 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="WQstIalo" Received: from smtp-4-0001.mail.infomaniak.ch (unknown [IPv6:2001:1600:7:10:40ca:feff:fe05:1]) by smtp-4-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4XXxwm1dmRzvm; Tue, 22 Oct 2024 18:10:32 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1729613432; bh=JIkFdcA2MSd0H2lV7JeqWVnBj8kE454w4i9hCEh/p08=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WQstIalo/8jZU1OYFvp0FdW++30j1fOyZZJqdKc1yLUnd0wsDTdEx+HI74LnYwu4m nhF4YH5RCw0nXACPx5pSi93ZxouwgFu/Rqcu+Qn97SA4HTLI82Fb8DwAYoLfo438Wp bRTC/Z4QnTcL2uJzcEZ8sJ6RG4gHCKdOSFXYRkJo= Received: from unknown by smtp-4-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4XXxwl2w77z1D4; Tue, 22 Oct 2024 18:10:31 +0200 (CEST) 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 , James Morris , Jann Horn , Jeff Xu , Jorge Lucangeli Obes , Kees Cook , Konstantin Meskhidze , Matt Bobrowski , Mikhail Ivanov , 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: [RFC PATCH v2 09/14] landlock: Log mount-related denials Date: Tue, 22 Oct 2024 18:10:04 +0200 Message-ID: <20241022161009.982584-10-mic@digikod.net> In-Reply-To: <20241022161009.982584-1-mic@digikod.net> References: <20241022161009.982584-1-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 record sample: DENY: blockers=fs_change_layout name="/" dev="tmpfs" ino=1 SYSCALL: arch=c000003e syscall=166 success=no exit=-1 ... Cc: Günther Noack Signed-off-by: Mickaël Salaün Link: https://lore.kernel.org/r/20241022161009.982584-10-mic@digikod.net --- Changes since v2: * Log the domain that denied the action because not all layers block FS layout changes. 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 f5860f396044..4cd9407459d2 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 e0e5775b75ae..a099167d2347 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" @@ -1308,6 +1310,38 @@ 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 @@ -1330,16 +1364,24 @@ 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; } @@ -1349,15 +1391,23 @@ 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; } @@ -1372,8 +1422,12 @@ 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 1fe88027404b..c463ff9a6615 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -278,6 +278,37 @@ landlock_match_ruleset(const struct landlock_ruleset *const ruleset, return NULL; } +/** + * landlock_match_layer_level - Return the layer level restricting @masks + * + * @ruleset: 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 ruleset, + const struct access_masks masks) +{ + const union access_masks_all masks_all = { + .masks = masks, + }; + size_t layer_level; + + for (layer_level = ruleset->num_layers; layer_level >= 0; + layer_level--) { + union access_masks_all layer = { + .masks = ruleset->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,