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

Pull overlayfs updates from Miklos Szeredi:
 "This update contains fixes to the "use mounter's permission to access
  underlying layers" area, and miscellaneous other fixes and cleanups.

  No new features this time"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: use vfs_get_link()
  vfs: add vfs_get_link() helper
  ovl: use generic_readlink
  ovl: explain error values when removing acl from workdir
  ovl: Fix info leak in ovl_lookup_temp()
  ovl: during copy up, switch to mounter's creds early
  ovl: lookup: do getxattr with mounter's permission
  ovl: copy_up_xattr(): use strnlen

1 files changed, 10 insertions, 34 deletions

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index c18d6a4ff456..c58f01babf30 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -19,6 +19,7 @@ static int ovl_copy_up_truncate(struct dentry *dentry)
 	struct dentry *parent;
 	struct kstat stat;
 	struct path lowerpath;
+	const struct cred *old_cred;
 
 	parent = dget_parent(dentry);
 	err = ovl_copy_up(parent);
@@ -26,12 +27,14 @@ static int ovl_copy_up_truncate(struct dentry *dentry)
 		goto out_dput_parent;
 
 	ovl_path_lower(dentry, &lowerpath);
-	err = vfs_getattr(&lowerpath, &stat);
-	if (err)
-		goto out_dput_parent;
 
-	stat.size = 0;
-	err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
+	old_cred = ovl_override_creds(dentry->d_sb);
+	err = vfs_getattr(&lowerpath, &stat);
+	if (!err) {
+		stat.size = 0;
+		err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
+	}
+	revert_creds(old_cred);
 
 out_dput_parent:
 	dput(parent);
@@ -153,45 +156,18 @@ static const char *ovl_get_link(struct dentry *dentry,
 				struct inode *inode,
 				struct delayed_call *done)
 {
-	struct dentry *realdentry;
-	struct inode *realinode;
 	const struct cred *old_cred;
 	const char *p;
 
 	if (!dentry)
 		return ERR_PTR(-ECHILD);
 
-	realdentry = ovl_dentry_real(dentry);
-	realinode = realdentry->d_inode;
-
-	if (WARN_ON(!realinode->i_op->get_link))
-		return ERR_PTR(-EPERM);
-
 	old_cred = ovl_override_creds(dentry->d_sb);
-	p = realinode->i_op->get_link(realdentry, realinode, done);
+	p = vfs_get_link(ovl_dentry_real(dentry), done);
 	revert_creds(old_cred);
 	return p;
 }
 
-static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
-{
-	struct path realpath;
-	struct inode *realinode;
-	const struct cred *old_cred;
-	int err;
-
-	ovl_path_real(dentry, &realpath);
-	realinode = realpath.dentry->d_inode;
-
-	if (!realinode->i_op->readlink)
-		return -EINVAL;
-
-	old_cred = ovl_override_creds(dentry->d_sb);
-	err = realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
-	revert_creds(old_cred);
-	return err;
-}
-
 bool ovl_is_private_xattr(const char *name)
 {
 	return strncmp(name, OVL_XATTR_PREFIX,
@@ -375,7 +351,7 @@ static const struct inode_operations ovl_file_inode_operations = {
 static const struct inode_operations ovl_symlink_inode_operations = {
 	.setattr	= ovl_setattr,
 	.get_link	= ovl_get_link,
-	.readlink	= ovl_readlink,
+	.readlink	= generic_readlink,
 	.getattr	= ovl_getattr,
 	.listxattr	= ovl_listxattr,
 	.update_time	= ovl_update_time,