From patchwork Thu Oct 8 15:30:57 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: 11823287 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 8357D1752 for ; Thu, 8 Oct 2020 15:32:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D35C21D20 for ; Thu, 8 Oct 2020 15:32:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731235AbgJHPcO (ORCPT ); Thu, 8 Oct 2020 11:32:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731060AbgJHPbe (ORCPT ); Thu, 8 Oct 2020 11:31:34 -0400 Received: from smtp-1909.mail.infomaniak.ch (smtp-1909.mail.infomaniak.ch [IPv6:2001:1600:3:17::1909]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D55DC0613DC; Thu, 8 Oct 2020 08:31:20 -0700 (PDT) Received: from smtp-3-0001.mail.infomaniak.ch (unknown [10.4.36.108]) by smtp-2-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4C6ZtH0lZczlhYCM; Thu, 8 Oct 2020 17:31:19 +0200 (CEST) Received: from localhost (unknown [94.23.54.103]) by smtp-3-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4C6ZtG5pz5zlmrrx; Thu, 8 Oct 2020 17:31:18 +0200 (CEST) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: linux-kernel@vger.kernel.org, James Morris , "Serge E . Hallyn" , Al Viro , Richard Weinberger Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Andy Lutomirski , Anton Ivanov , Arnd Bergmann , Casey Schaufler , Jann Horn , Jeff Dike , Jonathan Corbet , Kees Cook , Michael Kerrisk , 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-kselftest@vger.kernel.org, linux-security-module@vger.kernel.org, x86@kernel.org, =?utf-8?q?Micka?= =?utf-8?q?=C3=ABl_Sala=C3=BCn?= Subject: [PATCH v21 06/12] fs,security: Add sb_delete hook Date: Thu, 8 Oct 2020 17:30:57 +0200 Message-Id: <20201008153103.1155388-7-mic@digikod.net> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201008153103.1155388-1-mic@digikod.net> References: <20201008153103.1155388-1-mic@digikod.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org 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 --- 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 904459b35119..d5517e49ccdf 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 2a8c74d99015..a512d4796409 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 29df5075b35d..81f21861651e 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 0a0a03b36a3b..28b0ee6c7239 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -286,6 +286,7 @@ 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); @@ -614,6 +615,9 @@ 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 d60aa835b670..9337b511306c 100644 --- a/security/security.c +++ b/security/security.c @@ -898,6 +898,11 @@ 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);