commit c9f0f63b954eb43a41b67623428f12352be0747c
author Miklos Szeredi <mszeredi@redhat.com> Mon Aug 08 13:08:49 2016
committer ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> Fri Sep 30 07:37:09 2016
tree da5ea13a25a503f2760662fefccedaa561c13e6a
parent 5fe61ffa5042a6fecf591ac5d2e742cb686153be

UPSTREAM: ovl: don't copy up opaqueness

commit 0956254a2d5b9e2141385514553aeef694dfe3b5 upstream.

When a copy up of a directory occurs which has the opaque xattr set, the
xattr remains in the upper directory. The immediate behavior with overlayfs
is that the upper directory is not treated as opaque, however after a
remount the opaque flag is used and upper directory is treated as opaque.
This causes files created in the lower layer to be hidden when using
multiple lower directories.

Fix by not copying up the opaque flag.

To reproduce:

 ----8<---------8<---------8<---------8<---------8<---------8<----
mkdir -p l/d/s u v w mnt
mount -t overlay overlay -olowerdir=l,upperdir=u,workdir=w mnt
rm -rf mnt/d/
mkdir -p mnt/d/n
umount mnt
mount -t overlay overlay -olowerdir=u:l,upperdir=v,workdir=w mnt
touch mnt/d/foo
umount mnt
mount -t overlay overlay -olowerdir=u:l,upperdir=v,workdir=w mnt
ls mnt/d
 ----8<---------8<---------8<---------8<---------8<---------8<----

output should be:  "foo  n"

Reported-by: Derek McGowan <dmcg@drizz.net>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=151291
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(cherry picked from commit 48fd20d7237bfefd18750b1b38f426c7e210462d)
Signed-off-by: Edward Hyunkoo Jee <edjee@google.com>

BUG=chromium:651207
BUG=b:31266134
BUG=b:30869411
TEST=See the "TEST=" section of
     https://chromium-review.googlesource.com/391028
     ("ovl: fix workdir creation")

Change-Id: I894310d582343bb4fd584a2c2b9f8b1020448abb
Reviewed-on: https://chromium-review.googlesource.com/391024
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Commit-Queue: Edward Jee <edjee@google.com>
Tested-by: Edward Jee <edjee@google.com>
Trybot-Ready: Edward Jee <edjee@google.com>

fs/overlayfs/copy_up.c

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index eff6319..9e52609c 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -48,6 +48,8 @@
 	}
 
 	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
+		if (ovl_is_private_xattr(name))
+			continue;
 retry:
 		size = vfs_getxattr(old, name, value, value_size);
 		if (size == -ERANGE)

fs/overlayfs/inode.c

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 4f729ff..8f8bce4 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -219,7 +219,7 @@
 }
 
 
-static bool ovl_is_private_xattr(const char *name)
+bool ovl_is_private_xattr(const char *name)
 {
 	return strncmp(name, OVL_XATTR_PRE_NAME, OVL_XATTR_PRE_LEN) == 0;
 }

fs/overlayfs/overlayfs.h

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 735e1d49..c319d5e 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -174,6 +174,7 @@
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
 int ovl_removexattr(struct dentry *dentry, const char *name);
 struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags);
+bool ovl_is_private_xattr(const char *name);
 
 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
 			    struct ovl_entry *oe);