ovl: don't copy up opaqueness

[ Upstream commit 0956254a2d5b9e2141385514553aeef694dfe3b5 ]

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 54d62bd95e923f6a93969906d25d5eb2f900f0fd..4cb1c10c7706407595846332c50f0ab88fe2c8c3 100644 (file)
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -48,6 +48,8 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
        }
 
        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)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index fefce48e0f31166e86609625507557f66b53fd52..5403ba628bdec6709749e607c708e698af754bd7 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -208,8 +208,7 @@ static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
        return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
 }
 
-
-static bool ovl_is_private_xattr(const char *name)
+bool ovl_is_private_xattr(const char *name)
 {
        return strncmp(name, "trusted.overlay.", 14) == 0;
 }

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 00eb848faad83e29e0f96a32aa3e750448a6023a..f13557f411ae6863bde951dec67c1da62c78cc5d 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -166,6 +166,7 @@ ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
 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);