From patchwork Tue Oct 27 20:03:52 2020 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: 11861781 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 10106139F for ; Tue, 27 Oct 2020 20:11:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F408A22282 for ; Tue, 27 Oct 2020 20:11:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S372737AbgJ0ULL (ORCPT ); Tue, 27 Oct 2020 16:11:11 -0400 Received: from smtp-190f.mail.infomaniak.ch ([185.125.25.15]:42811 "EHLO smtp-190f.mail.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S372730AbgJ0ULK (ORCPT ); Tue, 27 Oct 2020 16:11:10 -0400 Received: from smtp-2-0001.mail.infomaniak.ch (unknown [10.5.36.108]) by smtp-2-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4CLN2N5ndxzlhBVL; Tue, 27 Oct 2020 21:04:12 +0100 (CET) Received: from localhost (unknown [94.23.54.103]) by smtp-2-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4CLN2N3H1Mzlh8T9; Tue, 27 Oct 2020 21:04:12 +0100 (CET) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: James Morris , "Serge E . Hallyn" Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Al Viro , Andy Lutomirski , Anton Ivanov , Arnd Bergmann , Casey Schaufler , Jann Horn , Jeff Dike , Jonathan Corbet , Kees Cook , Michael Kerrisk , Richard Weinberger , Shuah Khan , Vincent Dagonneau , kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-security-module@vger.kernel.org, x86@kernel.org, =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= Subject: [PATCH v22 06/12] fs,security: Add sb_delete hook Date: Tue, 27 Oct 2020 21:03:52 +0100 Message-Id: <20201027200358.557003-7-mic@digikod.net> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201027200358.557003-1-mic@digikod.net> References: <20201027200358.557003-1-mic@digikod.net> MIME-Version: 1.0 Precedence: bulk List-ID: From: Mickaël Salaün The sb_delete security hook is called when shutting down a superblock, which may be useful to release kernel objects tied to the superblock's lifetime (e.g. inodes). This new hook is needed by Landlock to release (ephemerally) tagged struct inodes. This comes from the unprivileged nature of Landlock described in the next commit. Cc: Al Viro Cc: James Morris Cc: Jann Horn Cc: Kees Cook Cc: Serge E. Hallyn Signed-off-by: Mickaël Salaün Reviewed-by: Jann Horn --- Changes since v17: * Initial patch to replace the direct call to landlock_release_inodes() (requested by James Morris). https://lore.kernel.org/lkml/alpine.LRH.2.21.2005150536440.7929@namei.org/ --- fs/super.c | 1 + include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 2 ++ include/linux/security.h | 4 ++++ security/security.c | 5 +++++ 5 files changed, 13 insertions(+) diff --git a/fs/super.c b/fs/super.c index a51c2083cd6b..fea9475189f7 100644 --- a/fs/super.c +++ b/fs/super.c @@ -454,6 +454,7 @@ void generic_shutdown_super(struct super_block *sb) evict_inodes(sb); /* only nonzero refcount inodes can have marks */ fsnotify_sb_delete(sb); + security_sb_delete(sb); if (sb->s_dio_done_wq) { destroy_workqueue(sb->s_dio_done_wq); diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 32a940117e7a..1ba9b4dfecb3 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -59,6 +59,7 @@ LSM_HOOK(int, 0, fs_context_dup, struct fs_context *fc, LSM_HOOK(int, -ENOPARAM, fs_context_parse_param, struct fs_context *fc, struct fs_parameter *param) LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb) +LSM_HOOK(void, LSM_RET_VOID, sb_delete, struct super_block *sb) LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb) LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts) LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts) diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index ff0f03a45c56..dbfcec05a176 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -108,6 +108,8 @@ * allocated. * @sb contains the super_block structure to be modified. * Return 0 if operation was successful. + * @sb_delete: + * Release objects tied to a superblock (e.g. inodes). * @sb_free_security: * Deallocate and clear the sb->s_security field. * @sb contains the super_block structure to be modified. diff --git a/include/linux/security.h b/include/linux/security.h index bc2725491560..a4603b62d444 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -287,6 +287,7 @@ void security_bprm_committed_creds(struct linux_binprm *bprm); int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc); int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param); int security_sb_alloc(struct super_block *sb); +void security_sb_delete(struct super_block *sb); void security_sb_free(struct super_block *sb); void security_free_mnt_opts(void **mnt_opts); int security_sb_eat_lsm_opts(char *options, void **mnt_opts); @@ -619,6 +620,9 @@ static inline int security_sb_alloc(struct super_block *sb) return 0; } +static inline void security_sb_delete(struct super_block *sb) +{ } + static inline void security_sb_free(struct super_block *sb) { } diff --git a/security/security.c b/security/security.c index 4ffd6c3af9d7..4563e7a79216 100644 --- a/security/security.c +++ b/security/security.c @@ -899,6 +899,11 @@ int security_sb_alloc(struct super_block *sb) return rc; } +void security_sb_delete(struct super_block *sb) +{ + call_void_hook(sb_delete, sb); +} + void security_sb_free(struct super_block *sb) { call_void_hook(sb_free_security, sb);