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From: "Serge E. Hallyn" <serge@hallyn.com>
To: "Mickaël Salaün" <mic@digikod.net>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
	"James Morris" <jmorris@namei.org>,
	"Jann Horn" <jannh@google.com>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Andy Lutomirski" <luto@amacapital.net>,
	"Anton Ivanov" <anton.ivanov@cambridgegreys.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Casey Schaufler" <casey@schaufler-ca.com>,
	"Jeff Dike" <jdike@addtoit.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Kees Cook" <keescook@chromium.org>,
	"Michael Kerrisk" <mtk.manpages@gmail.com>,
	"Richard Weinberger" <richard@nod.at>,
	"Shuah Khan" <shuah@kernel.org>,
	"Vincent Dagonneau" <vincent.dagonneau@ssi.gouv.fr>,
	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,
	"Mickaël Salaün" <mic@linux.microsoft.com>
Subject: Re: [PATCH v28 06/12] fs,security: Add sb_delete hook
Date: Sat, 6 Feb 2021 22:18:14 -0600	[thread overview]
Message-ID: <20210207041814.GA7955@mail.hallyn.com> (raw)
In-Reply-To: <92e6a8a6-19da-0b1f-c1cf-01dc0af61299@digikod.net>

On Fri, Feb 05, 2021 at 03:57:37PM +0100, Mickaël Salaün wrote:
> 
> On 05/02/2021 15:21, Serge E. Hallyn wrote:
> > On Tue, Feb 02, 2021 at 05:27:04PM +0100, Mickaël Salaün wrote:
> >> From: Mickaël Salaün <mic@linux.microsoft.com>
> >>
> >> 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 <viro@zeniv.linux.org.uk>
> >> Cc: James Morris <jmorris@namei.org>
> >> Cc: Kees Cook <keescook@chromium.org>
> >> Cc: Serge E. Hallyn <serge@hallyn.com>
> > 
> > One note below, but
> > 
> > Acked-by: Serge Hallyn <serge@hallyn.com>
> > 
> >> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
> >> Reviewed-by: Jann Horn <jannh@google.com>
> >> ---
> >>
> >> Changes since v22:
> >> * Add Reviewed-by: Jann Horn <jannh@google.com>
> >>
> >> 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.
> 
> What about "@sb contains the super_block structure being released."?

That's good.  Thanks.

> > 
> >>   * @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

  reply	other threads:[~2021-02-07  4:19 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-02 16:26 [PATCH v28 00/12] Landlock LSM Mickaël Salaün
2021-02-02 16:26 ` [PATCH v28 01/12] landlock: Add object management Mickaël Salaün
2021-02-03 14:21   ` Serge E. Hallyn
2021-02-03 15:27     ` Mickaël Salaün
2021-02-02 16:27 ` [PATCH v28 02/12] landlock: Add ruleset and domain management Mickaël Salaün
2021-02-04  3:30   ` Serge E. Hallyn
2021-02-02 16:27 ` [PATCH v28 03/12] landlock: Set up the security framework and manage credentials Mickaël Salaün
2021-02-04  3:46   ` Serge E. Hallyn
2021-02-02 16:27 ` [PATCH v28 04/12] landlock: Add ptrace restrictions Mickaël Salaün
2021-02-05 13:48   ` Serge E. Hallyn
2021-02-02 16:27 ` [PATCH v28 05/12] LSM: Infrastructure management of the superblock Mickaël Salaün
2021-02-05 14:17   ` Serge E. Hallyn
2021-02-05 16:51     ` Casey Schaufler
2021-02-05 16:51     ` Casey Schaufler
2021-02-02 16:27 ` [PATCH v28 06/12] fs,security: Add sb_delete hook Mickaël Salaün
2021-02-05 14:21   ` Serge E. Hallyn
2021-02-05 14:57     ` Mickaël Salaün
2021-02-07  4:18       ` Serge E. Hallyn [this message]
2021-02-02 16:27 ` [PATCH v28 07/12] landlock: Support filesystem access-control Mickaël Salaün
2021-02-10 19:36   ` Serge E. Hallyn
2021-02-10 20:17     ` Mickaël Salaün
2021-02-19 15:34       ` Serge E. Hallyn
2021-02-02 16:27 ` [PATCH v28 08/12] landlock: Add syscall implementations Mickaël Salaün
2021-02-03 15:04   ` Serge E. Hallyn
2021-02-02 16:27 ` [PATCH v28 09/12] arch: Wire up Landlock syscalls Mickaël Salaün
2021-02-02 16:27 ` [PATCH v28 10/12] selftests/landlock: Add user space tests Mickaël Salaün
2021-02-02 16:27 ` [PATCH v28 11/12] samples/landlock: Add a sandbox manager example Mickaël Salaün
2021-02-02 16:27 ` [PATCH v28 12/12] landlock: Add user and kernel documentation Mickaël Salaün

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