From mboxrd@z Thu Jan 1 00:00:00 1970 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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 C7F95C433DB for ; Fri, 5 Feb 2021 20:13:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C8B764FBB for ; Fri, 5 Feb 2021 20:13:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233430AbhBESaq (ORCPT ); Fri, 5 Feb 2021 13:30:46 -0500 Received: from mail.hallyn.com ([178.63.66.53]:53330 "EHLO mail.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233134AbhBEPND (ORCPT ); Fri, 5 Feb 2021 10:13:03 -0500 Received: by mail.hallyn.com (Postfix, from userid 1001) id 30841283; Fri, 5 Feb 2021 08:21:43 -0600 (CST) Date: Fri, 5 Feb 2021 08:21:43 -0600 From: "Serge E. Hallyn" To: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= Cc: James Morris , Jann Horn , "Serge E . Hallyn" , Al Viro , Andrew Morton , Andy Lutomirski , Anton Ivanov , Arnd Bergmann , Casey Schaufler , 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, =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= Subject: Re: [PATCH v28 06/12] fs,security: Add sb_delete hook Message-ID: <20210205142143.GA18451@mail.hallyn.com> References: <20210202162710.657398-1-mic@digikod.net> <20210202162710.657398-7-mic@digikod.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210202162710.657398-7-mic@digikod.net> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 02, 2021 at 05:27:04PM +0100, Mickaël Salaün wrote: > 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: Kees Cook > Cc: Serge E. Hallyn One note below, but Acked-by: Serge Hallyn > Signed-off-by: Mickaël Salaün > Reviewed-by: Jann Horn > --- > > 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 | 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 2c6cdea2ab2d..c3c5178cde65 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 7aaa753b8608..32472b3849bc 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 970106d98306..e339b201f79b 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). It's customary here to add the line detailing the @sb argument. > * @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 c35ea0ffccd9..c41a94e29b62 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -288,6 +288,7 @@ 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); > @@ -620,6 +621,9 @@ 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 9f979d4afe6c..1b4a73b2549a 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); > -- > 2.30.0