From patchwork Thu Apr 22 15:41:16 2021 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: 12218707 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE3CFC43616 for ; Thu, 22 Apr 2021 15:42:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6F90960FD7 for ; Thu, 22 Apr 2021 15:42:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238329AbhDVPmq (ORCPT ); Thu, 22 Apr 2021 11:42:46 -0400 Received: from smtp-42a8.mail.infomaniak.ch ([84.16.66.168]:40851 "EHLO smtp-42a8.mail.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238087AbhDVPmT (ORCPT ); Thu, 22 Apr 2021 11:42:19 -0400 Received: from smtp-3-0000.mail.infomaniak.ch (unknown [10.4.36.107]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4FR1qm0Qn7zMqLdL; Thu, 22 Apr 2021 17:41:40 +0200 (CEST) Received: from localhost (unknown [23.97.221.149]) by smtp-3-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4FR1ql53qWzlh8TH; Thu, 22 Apr 2021 17:41:39 +0200 (CEST) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: James Morris , Jann Horn , Kees Cook , "Serge E . Hallyn" Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Al Viro , Andy Lutomirski , Anton Ivanov , Arnd Bergmann , Casey Schaufler , David Howells , Jeff Dike , Jonathan Corbet , 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 v34 06/13] fs,security: Add sb_delete hook Date: Thu, 22 Apr 2021 17:41:16 +0200 Message-Id: <20210422154123.13086-7-mic@digikod.net> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210422154123.13086-1-mic@digikod.net> References: <20210422154123.13086-1-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 Signed-off-by: Mickaël Salaün Reviewed-by: Jann Horn Acked-by: Serge Hallyn Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20210422154123.13086-7-mic@digikod.net --- Changes since v30: * Add Reviewed-by Kees Cook. Changes since v28: * Extend hook description (suggested by Serge Hallyn). * Add Acked-by Serge Hallyn. Changes since v22: * Add 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 | 3 +++ include/linux/security.h | 4 ++++ security/security.c | 5 +++++ 5 files changed, 14 insertions(+) diff --git a/fs/super.c b/fs/super.c index 8c1baca35c16..11b7e7213fd1 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 477a597db013..e8adadbf9581 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 75715998a95f..cc2eaaaec0e4 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -108,6 +108,9 @@ * 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 contains the super_block structure being released. * @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 8aeebd6646dc..90298baa4551 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -291,6 +291,7 @@ 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); @@ -631,6 +632,9 @@ 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 e9c29480eb18..bb666f992497 100644 --- a/security/security.c +++ b/security/security.c @@ -900,6 +900,11 @@ 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);