linux-kernel - [PATCH v7 13/28] landlock: Factor out IOCTL hooks

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Message-ID: <20250320190717.2287696-14-mic@digikod.net>
Date: Thu, 20 Mar 2025 20:07:02 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: Eric Paris <eparis@...hat.com>,
	Paul Moore <paul@...l-moore.com>,
	Günther Noack <gnoack@...gle.com>,
	"Serge E . Hallyn" <serge@...lyn.com>
Cc: Mickaël Salaün <mic@...ikod.net>,
	Ben Scarlato <akhna@...gle.com>,
	Casey Schaufler <casey@...aufler-ca.com>,
	Charles Zaffery <czaffery@...lox.com>,
	Daniel Burgener <dburgener@...ux.microsoft.com>,
	Francis Laniel <flaniel@...ux.microsoft.com>,
	James Morris <jmorris@...ei.org>,
	Jann Horn <jannh@...gle.com>,
	Jeff Xu <jeffxu@...gle.com>,
	Jorge Lucangeli Obes <jorgelo@...gle.com>,
	Kees Cook <kees@...nel.org>,
	Konstantin Meskhidze <konstantin.meskhidze@...wei.com>,
	Matt Bobrowski <mattbobrowski@...gle.com>,
	Matthieu Buffet <matthieu@...fet.re>,
	Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>,
	Phil Sutter <phil@....cc>,
	Praveen K Paladugu <prapal@...ux.microsoft.com>,
	Robert Salvet <robert.salvet@...lox.com>,
	Shervin Oloumi <enlightened@...gle.com>,
	Song Liu <song@...nel.org>,
	Tahera Fahimi <fahimitahera@...il.com>,
	Tingmao Wang <m@...wtm.org>,
	Tyler Hicks <code@...icks.com>,
	audit@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org
Subject: [PATCH v7 13/28] landlock: Factor out IOCTL hooks

Compat and non-compat IOCTL hooks are almost the same, except to compare
the IOCTL command.  Factor out these two IOCTL hooks to highlight the
difference and minimize audit changes (see next commit).

Cc: Günther Noack <gnoack@...gle.com>
Signed-off-by: Mickaël Salaün <mic@...ikod.net>
---

Changes since v6:
- New patch.
---
 security/landlock/fs.c | 32 +++++++++++---------------------
 1 file changed, 11 insertions(+), 21 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index ba03439caab9..c67ef35248e3 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -1698,8 +1698,8 @@ static int hook_file_truncate(struct file *const file)
 	return -EACCES;
 }
 
-static int hook_file_ioctl(struct file *file, unsigned int cmd,
-			   unsigned long arg)
+static int hook_file_ioctl_common(const struct file *const file,
+				  const unsigned int cmd, const bool is_compat)
 {
 	access_mask_t allowed_access = landlock_file(file)->allowed_access;
 
@@ -1715,33 +1715,23 @@ static int hook_file_ioctl(struct file *file, unsigned int cmd,
 	if (!is_device(file))
 		return 0;
 
-	if (is_masked_device_ioctl(cmd))
+	if (unlikely(is_compat) ? is_masked_device_ioctl_compat(cmd) :
+				  is_masked_device_ioctl(cmd))
 		return 0;
 
 	return -EACCES;
 }
 
+static int hook_file_ioctl(struct file *file, unsigned int cmd,
+			   unsigned long arg)
+{
+	return hook_file_ioctl_common(file, cmd, false);
+}
+
 static int hook_file_ioctl_compat(struct file *file, unsigned int cmd,
 				  unsigned long arg)
 {
-	access_mask_t allowed_access = landlock_file(file)->allowed_access;
-
-	/*
-	 * It is the access rights at the time of opening the file which
-	 * determine whether IOCTL can be used on the opened file later.
-	 *
-	 * The access right is attached to the opened file in hook_file_open().
-	 */
-	if (allowed_access & LANDLOCK_ACCESS_FS_IOCTL_DEV)
-		return 0;
-
-	if (!is_device(file))
-		return 0;
-
-	if (is_masked_device_ioctl_compat(cmd))
-		return 0;
-
-	return -EACCES;
+	return hook_file_ioctl_common(file, cmd, true);
 }
 
 static void hook_file_set_fowner(struct file *file)
-- 
2.49.0