linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Mickaël Salaün" <mic@digikod.net>
To: James Morris <jmorris@namei.org>, "Serge E . Hallyn" <serge@hallyn.com>
Cc: "Mickaël Salaün" <mic@digikod.net>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Andy Lutomirski" <luto@amacapital.net>,
	"Anton Ivanov" <anton.ivanov@cambridgegreys.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Casey Schaufler" <casey@schaufler-ca.com>,
	"Jann Horn" <jannh@google.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: [PATCH v24 06/12] fs,security: Add sb_delete hook
Date: Thu, 12 Nov 2020 21:51:35 +0100	[thread overview]
Message-ID: <20201112205141.775752-7-mic@digikod.net> (raw)
In-Reply-To: <20201112205141.775752-1-mic@digikod.net>

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>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
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 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);
-- 
2.29.2


  parent reply	other threads:[~2020-11-12 20:52 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12 20:51 [PATCH v24 00/12] Landlock LSM Mickaël Salaün
2020-11-12 20:51 ` [PATCH v24 01/12] landlock: Add object management Mickaël Salaün
2020-11-21  7:00   ` Jann Horn
2020-11-21 10:11     ` Mickaël Salaün
2020-11-12 20:51 ` [PATCH v24 02/12] landlock: Add ruleset and domain management Mickaël Salaün
2020-11-20  1:52   ` James Morris
2020-11-21  7:00   ` Jann Horn
2020-11-21  9:45     ` Mickaël Salaün
2020-11-12 20:51 ` [PATCH v24 03/12] landlock: Set up the security framework and manage credentials Mickaël Salaün
2020-11-12 20:51 ` [PATCH v24 04/12] landlock: Add ptrace restrictions Mickaël Salaün
2020-11-12 20:51 ` [PATCH v24 05/12] LSM: Infrastructure management of the superblock Mickaël Salaün
2020-11-12 20:51 ` Mickaël Salaün [this message]
2020-11-12 20:51 ` [PATCH v24 07/12] landlock: Support filesystem access-control Mickaël Salaün
2020-11-21  7:00   ` Jann Horn
2020-11-21 10:06     ` Mickaël Salaün
2020-11-23 19:44       ` Jann Horn
2020-11-23 21:16         ` Mickaël Salaün
2020-11-23 21:19           ` Jann Horn
2020-11-12 20:51 ` [PATCH v24 08/12] landlock: Add syscall implementations Mickaël Salaün
2020-11-21  7:00   ` Jann Horn
2020-11-12 20:51 ` [PATCH v24 09/12] arch: Wire up Landlock syscalls Mickaël Salaün
2020-11-12 20:51 ` [PATCH v24 10/12] selftests/landlock: Add user space tests Mickaël Salaün
2020-11-12 20:51 ` [PATCH v24 11/12] samples/landlock: Add a sandbox manager example Mickaël Salaün
2020-11-12 20:51 ` [PATCH v24 12/12] landlock: Add user and kernel documentation Mickaël Salaün
2020-11-21  7:00   ` Jann Horn
2020-11-24  2:38     ` James Morris
2020-11-17  5:37 ` [PATCH v24 00/12] Landlock LSM James Morris

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201112205141.775752-7-mic@digikod.net \
    --to=mic@digikod.net \
    --cc=anton.ivanov@cambridgegreys.com \
    --cc=arnd@arndb.de \
    --cc=casey@schaufler-ca.com \
    --cc=corbet@lwn.net \
    --cc=jannh@google.com \
    --cc=jdike@addtoit.com \
    --cc=jmorris@namei.org \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mic@linux.microsoft.com \
    --cc=mtk.manpages@gmail.com \
    --cc=richard@nod.at \
    --cc=serge@hallyn.com \
    --cc=shuah@kernel.org \
    --cc=vincent.dagonneau@ssi.gouv.fr \
    --cc=viro@zeniv.linux.org.uk \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH v24 06/12] fs,security: Add sb_delete hook' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).