[PATCH v6 33/40] fs: add attr_flags_to_mnt_flags helper

From: Christian Brauner <christian.brauner@ubuntu.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>,
	Christoph Hellwig <hch@lst.de>,
	linux-fsdevel@vger.kernel.org
Cc: Lennart Poettering <lennart@poettering.net>,
	Mimi Zohar <zohar@linux.ibm.com>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	containers@lists.linux-foundation.org,
	Tycho Andersen <tycho@tycho.ws>, Paul Moore <paul@paul-moore.com>,
	Jonathan Corbet <corbet@lwn.net>,
	smbarber@chromium.org, linux-ext4@vger.kernel.org,
	Mrunal Patel <mpatel@redhat.com>,
	Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
	selinux@vger.kernel.org, Josh Triplett <josh@joshtriplett.org>,
	Seth Forshee <seth.forshee@canonical.com>,
	Aleksa Sarai <cyphar@cyphar.com>,
	Andy Lutomirski <luto@kernel.org>,
	OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
	Geoffrey Thomas <geofft@ldpreload.com>,
	David Howells <dhowells@redhat.com>,
	John Johansen <john.johansen@canonical.com>,
	Theodore Tso <tytso@mit.edu>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	Stephen Smalley <stephen.smalley.work@gmail.com>,
	linux-xfs@vger.kernel.org, linux-security-module@vger.kernel.org,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	linux-api@vger.kernel.org,
	Casey Schaufler <casey@schaufler-ca.com>,
	Alban Crequy <alban@kinvolk.io>,
	linux-integrity@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Todd Kjos <tkjos@google.com>
Subject: [PATCH v6 33/40] fs: add attr_flags_to_mnt_flags helper
Date: Thu, 21 Jan 2021 14:19:52 +0100	[thread overview]
Message-ID: <20210121131959.646623-34-christian.brauner@ubuntu.com> (raw)
In-Reply-To: <20210121131959.646623-1-christian.brauner@ubuntu.com>

Add a simple helper to translate uapi MOUNT_ATTR_* flags to MNT_* flags
which we will use in follow-up patches too.

Link: https://lore.kernel.org/r/20210112220124.837960-6-christian.brauner@ubuntu.com
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
patch not present

/* v3 */
patch not present

/* v4 */
patch introduced

/* v5 */
unchanged
base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837

/* v6 */
unchanged
base-commit: 19c329f6808995b142b3966301f217c831e7cf31
---
 fs/namespace.c | 40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 774ae5f74716..00ed0d6cb2ee 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3465,6 +3465,28 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
 	return ret;
 }
 
+#define FSMOUNT_VALID_FLAGS \
+	(MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID | MOUNT_ATTR_NODEV | \
+	 MOUNT_ATTR_NOEXEC | MOUNT_ATTR__ATIME | MOUNT_ATTR_NODIRATIME)
+
+static unsigned int attr_flags_to_mnt_flags(u64 attr_flags)
+{
+	unsigned int mnt_flags = 0;
+
+	if (attr_flags & MOUNT_ATTR_RDONLY)
+		mnt_flags |= MNT_READONLY;
+	if (attr_flags & MOUNT_ATTR_NOSUID)
+		mnt_flags |= MNT_NOSUID;
+	if (attr_flags & MOUNT_ATTR_NODEV)
+		mnt_flags |= MNT_NODEV;
+	if (attr_flags & MOUNT_ATTR_NOEXEC)
+		mnt_flags |= MNT_NOEXEC;
+	if (attr_flags & MOUNT_ATTR_NODIRATIME)
+		mnt_flags |= MNT_NODIRATIME;
+
+	return mnt_flags;
+}
+
 /*
  * Create a kernel mount representation for a new, prepared superblock
  * (specified by fs_fd) and attach to an open_tree-like file descriptor.
@@ -3487,24 +3509,10 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags,
 	if ((flags & ~(FSMOUNT_CLOEXEC)) != 0)
 		return -EINVAL;
 
-	if (attr_flags & ~(MOUNT_ATTR_RDONLY |
-			   MOUNT_ATTR_NOSUID |
-			   MOUNT_ATTR_NODEV |
-			   MOUNT_ATTR_NOEXEC |
-			   MOUNT_ATTR__ATIME |
-			   MOUNT_ATTR_NODIRATIME))
+	if (attr_flags & ~FSMOUNT_VALID_FLAGS)
 		return -EINVAL;
 
-	if (attr_flags & MOUNT_ATTR_RDONLY)
-		mnt_flags |= MNT_READONLY;
-	if (attr_flags & MOUNT_ATTR_NOSUID)
-		mnt_flags |= MNT_NOSUID;
-	if (attr_flags & MOUNT_ATTR_NODEV)
-		mnt_flags |= MNT_NODEV;
-	if (attr_flags & MOUNT_ATTR_NOEXEC)
-		mnt_flags |= MNT_NOEXEC;
-	if (attr_flags & MOUNT_ATTR_NODIRATIME)
-		mnt_flags |= MNT_NODIRATIME;
+	mnt_flags = attr_flags_to_mnt_flags(attr_flags);
 
 	switch (attr_flags & MOUNT_ATTR__ATIME) {
 	case MOUNT_ATTR_STRICTATIME:
-- 
2.30.0

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