From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 90F32413D70; Fri, 15 May 2026 20:02:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778875324; cv=none; b=V6Ycp/5+ijFaFB/atJGaCYfVcpB38n2Xt+Ky2l15EK7LXBE8v9E2UrYDjV4CDa2PNA7K/uc23gva4nEZlJ76misMrKqdODZgZG6dEq0zCRg14IVM+2eiw3X83vs+q73YlmGPcIfu0p5Kuto9ozWu3LQr8AyS57r8EzUrOHmVNSc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778875324; c=relaxed/simple; bh=H3mauhjxXzt3MNQ8wiMIz9gf//TGdRnFjHyrwfsKtKk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=diUVOip1dYPMzYkJoFaeyGKPYSVBhIT9qsRG26JP9BJJp9LnEQxGwwr6nCK1lhgrniGb3xcZD6E46VZF+uFcWLSDy+yK8pzIBaV7HKlRiDG6ZqQaPjXD3jyA4+/Sp0D1XlR3U2XtwdCEyQNQwlgMEUn/Ns4m23oABXk3IaOwuKc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ymr48TPh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ymr48TPh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9ABD9C2BCB3; Fri, 15 May 2026 20:02:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778875324; bh=H3mauhjxXzt3MNQ8wiMIz9gf//TGdRnFjHyrwfsKtKk=; h=From:To:Cc:Subject:Date:From; b=Ymr48TPha+NxkbyIp7QknXbyjmcq/HjAkmjWfswQCWmTL7/oS3qXgEI9njVSL396g WqM+TsEtwDcaHrgpzJnvYALMccS+ryprcdU+OKq+HSP0cY4Gbht/La0b9z+hRCE/Up 05iI+J3jKERBWBQeEsyGCYwLM6xXdAdYO31ev1gRuo/d82Jj2e4pEniz4mj7gHB7zc khZDBQ96fro0UTs3qmo5OrgotHiUrlWK5sBWmBV6g+xXVgpmRUF5FoZkrm/gdn35kY 3YgT/EtwXExE/vQBPBG1y5NONPW/iCvGx+R9wzePHgGSkmZOjv+/7yH6iCb7FPns/K vGi1+MHS0WRoA== From: Song Liu To: linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, selinux@vger.kernel.org, apparmor@lists.ubuntu.com Cc: paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, john.johansen@canonical.com, stephen.smalley.work@gmail.com, omosnace@redhat.com, mic@digikod.net, gnoack@google.com, takedakn@nttdata.co.jp, penguin-kernel@I-love.SAKURA.ne.jp, herton@canonical.com, kernel-team@meta.com, Song Liu Subject: [PATCH v4 0/7] lsm: Replace security_sb_mount with granular mount hooks Date: Fri, 15 May 2026 13:01:51 -0700 Message-ID: <20260515200158.4081915-1-song@kernel.org> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This series replaces the monolithic security_sb_mount() hook with per-operation mount hooks, addressing two main issues: 1. TOCTOU: security_sb_mount() receives dev_name as a string, which LSMs like AppArmor and Tomoyo re-resolve via kern_path(). The new hooks pass pre-resolved struct path pointers where possible (bind mount, move mount), eliminating the double-resolution. 2. Conflation: security_sb_mount() handles bind, new mount, remount, move, propagation changes, and mount reconfiguration through a single hook, requiring LSMs to dispatch on flags internally. The new hooks are called at the operation level with appropriate context. The new hooks are: mount_bind - bind mount (pre-resolved source path) mount_new - new filesystem mount (with fs_context) mount_remount - filesystem remount (with fs_context) mount_reconfigure - mount flag reconfiguration (MS_REMOUNT|MS_BIND) mount_move - move mount (pre-resolved paths) mount_change_type - propagation type changes mount_new and mount_remount are called after parse_monolithic_mount_data(), so LSMs have access to the fs_context with parsed mount options. They also receive the original mount(2) flags and data pointer for LSMs (AppArmor, Tomoyo) that need them for policy matching. The series also replaces security_move_mount() with the new mount_move hook, unifying the old mount(2) MS_MOVE path with the move_mount(2) syscall path. All existing LSM behaviors are preserved: AppArmor: same policy matching, TOCTOU fixed for bind/move SELinux: same permission checks (FILE__MOUNTON, FILESYSTEM__REMOUNT) Landlock: same deny-all for sandboxed processes Tomoyo: same policy matching, TOCTOU fixed for bind/move, unused data_page parameter removed This work is inspired by earlier discussions: [1] https://lore.kernel.org/bpf/20251127005011.1872209-1-song@kernel.org/ [2] https://lore.kernel.org/linux-security-module/20250708230504.3994335-1-song@kernel.org/ Changes v3 => v4: 1. Move LSM_HOOK_INIT(move_mount, ...) removal from patch 7/7 to each per-LSM conversion patch (3/7, 4/7, 5/7). (Paul Moore) 2. Add kdoc comments to tomoyo mount hook functions and rename tomoyo_move_mount to tomoyo_mount_move in patch 6/7. (Tetsuo Handa) 3. Add Acked-by from Tetsuo Handa to patch 6/7. v3: https://lore.kernel.org/linux-security-module/20260509015208.3853132-1-song@kernel.org/ Changes v2 => v3: 1. Rebase. 2. Move security_mount_move() call in vfs_move_mount() from patch 7/7 to patch 1/7. (Paul Moore) v2: https://lore.kernel.org/linux-security-module/20260430000315.918964-1-song@kernel.org/ Changes v1 => v2: 1. Rebase. 2. Add Reviewed-by and Tested-by from Stephen Smalley. v1: https://lore.kernel.org/linux-security-module/20260318184400.3502908-1-song@kernel.org/ Song Liu (7): lsm: Add granular mount hooks to replace security_sb_mount apparmor: Remove redundant MS_MGC_MSK stripping in apparmor_sb_mount apparmor: Convert from sb_mount to granular mount hooks selinux: Convert from sb_mount to granular mount hooks landlock: Convert from sb_mount to granular mount hooks tomoyo: Convert from sb_mount to granular mount hooks lsm: Remove security_sb_mount and security_move_mount fs/namespace.c | 41 +++++++--- include/linux/lsm_hook_defs.h | 14 +++- include/linux/security.h | 56 +++++++++++--- kernel/bpf/bpf_lsm.c | 7 +- security/apparmor/include/mount.h | 5 +- security/apparmor/lsm.c | 102 ++++++++++++++++++------- security/apparmor/mount.c | 37 ++-------- security/landlock/fs.c | 41 ++++++++-- security/security.c | 119 +++++++++++++++++++++++------- security/selinux/hooks.c | 49 ++++++++---- security/tomoyo/common.h | 2 +- security/tomoyo/mount.c | 31 +++++--- security/tomoyo/tomoyo.c | 109 ++++++++++++++++++++++++--- 13 files changed, 457 insertions(+), 156 deletions(-) -- 2.53.0-Meta