Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "This contains two regression fixes: one for the xattr API update and
  one for using the mounter's creds in file creation in overlayfs.

  There's also a fix for a bug in handling hard linked AF_UNIX sockets
  that's been there from day one.  This fix is overlayfs only despite
  the fact that it touches code outside the overlay filesystem: d_real()
  is an identity function for all except overlay dentries"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: fix uid/gid when creating over whiteout
  ovl: xattr filter fix
  af_unix: fix hard linked sockets on overlay
  vfs: add d_real_inode() helper

4 files changed, 32 insertions, 25 deletions

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 22f0253a3567..c2a6b0894022 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -405,12 +405,21 @@ static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
 		err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
 	} else {
 		const struct cred *old_cred;
+		struct cred *override_cred;
 
 		old_cred = ovl_override_creds(dentry->d_sb);
 
-		err = ovl_create_over_whiteout(dentry, inode, &stat, link,
-					       hardlink);
+		err = -ENOMEM;
+		override_cred = prepare_creds();
+		if (override_cred) {
+			override_cred->fsuid = old_cred->fsuid;
+			override_cred->fsgid = old_cred->fsgid;
+			put_cred(override_creds(override_cred));
+			put_cred(override_cred);
 
+			err = ovl_create_over_whiteout(dentry, inode, &stat,
+						       link, hardlink);
+		}
 		revert_creds(old_cred);
 	}
 
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 0ed7c4012437..1dbeab6cf96e 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -238,41 +238,27 @@ out:
 	return err;
 }
 
-static bool ovl_need_xattr_filter(struct dentry *dentry,
-				  enum ovl_path_type type)
-{
-	if ((type & (__OVL_PATH_PURE | __OVL_PATH_UPPER)) == __OVL_PATH_UPPER)
-		return S_ISDIR(dentry->d_inode->i_mode);
-	else
-		return false;
-}
-
 ssize_t ovl_getxattr(struct dentry *dentry, struct inode *inode,
 		     const char *name, void *value, size_t size)
 {
-	struct path realpath;
-	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
+	struct dentry *realdentry = ovl_dentry_real(dentry);
 
-	if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
+	if (ovl_is_private_xattr(name))
 		return -ENODATA;
 
-	return vfs_getxattr(realpath.dentry, name, value, size);
+	return vfs_getxattr(realdentry, name, value, size);
 }
 
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 {
-	struct path realpath;
-	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
+	struct dentry *realdentry = ovl_dentry_real(dentry);
 	ssize_t res;
 	int off;
 
-	res = vfs_listxattr(realpath.dentry, list, size);
+	res = vfs_listxattr(realdentry, list, size);
 	if (res <= 0 || size == 0)
 		return res;
 
-	if (!ovl_need_xattr_filter(dentry, type))
-		return res;
-
 	/* filter out private xattrs */
 	for (off = 0; off < res;) {
 		char *s = list + off;
@@ -302,7 +288,7 @@ int ovl_removexattr(struct dentry *dentry, const char *name)
 		goto out;
 
 	err = -ENODATA;
-	if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
+	if (ovl_is_private_xattr(name))
 		goto out_drop_write;
 
 	if (!OVL_TYPE_UPPER(type)) {
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 484c8792da82..f28100f6b556 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -575,5 +575,17 @@ static inline struct inode *vfs_select_inode(struct dentry *dentry,
 	return inode;
 }
 
+/**
+ * d_real_inode - Return the real inode
+ * @dentry: The dentry to query
+ *
+ * If dentry is on an union/overlay, then return the underlying, real inode.
+ * Otherwise return d_inode().
+ */
+static inline struct inode *d_real_inode(struct dentry *dentry)
+{
+	return d_backing_inode(d_real(dentry));
+}
+
 
 #endif	/* __LINUX_DCACHE_H */
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 80aa6a3e6817..735362c26c8e 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -315,7 +315,7 @@ static struct sock *unix_find_socket_byinode(struct inode *i)
 		    &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
 		struct dentry *dentry = unix_sk(s)->path.dentry;
 
-		if (dentry && d_backing_inode(dentry) == i) {
+		if (dentry && d_real_inode(dentry) == i) {
 			sock_hold(s);
 			goto found;
 		}
@@ -911,7 +911,7 @@ static struct sock *unix_find_other(struct net *net,
 		err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
 		if (err)
 			goto fail;
-		inode = d_backing_inode(path.dentry);
+		inode = d_real_inode(path.dentry);
 		err = inode_permission(inode, MAY_WRITE);
 		if (err)
 			goto put_fail;
@@ -1048,7 +1048,7 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 			goto out_up;
 		}
 		addr->hash = UNIX_HASH_SIZE;
-		hash = d_backing_inode(dentry)->i_ino & (UNIX_HASH_SIZE - 1);
+		hash = d_real_inode(dentry)->i_ino & (UNIX_HASH_SIZE - 1);
 		spin_lock(&unix_table_lock);
 		u->path = u_path;
 		list = &unix_socket_table[hash];