From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Thu, 21 Jan 2021 13:19:38 +0000 (+0100)
Subject: fcntl: handle idmapped mounts
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9eccd12ce7f1c063a5ff03d8b8456b2b9761c6b6;p=linux.git

fcntl: handle idmapped mounts

Enable the setfl() helper to handle idmapped mounts by passing down the
mount's user namespace. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-20-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 74d99731fd434..f6ac5285060d6 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -25,6 +25,7 @@
 #include <linux/user_namespace.h>
 #include <linux/memfd.h>
 #include <linux/compat.h>
+#include <linux/mount.h>
 
 #include <linux/poll.h>
 #include <asm/siginfo.h>
@@ -46,7 +47,7 @@ static int setfl(int fd, struct file * filp, unsigned long arg)
 
 	/* O_NOATIME can only be set by the owner or superuser */
 	if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
-		if (!inode_owner_or_capable(&init_user_ns, inode))
+		if (!inode_owner_or_capable(file_mnt_user_ns(filp), inode))
 			return -EPERM;
 
 	/* required for strict SunOS emulation */