On Thu, Feb 15, 2018 at 4:30 PM, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2ba9d57e65044859f7ff133bcb0a902769bf3bc6 Mon Sep 17 00:00:00 2001 From: Amir Goldstein amir73il@gmail.com Date: Wed, 3 Jan 2018 18:54:41 +0200 Subject: [PATCH] ovl: take mnt_want_write() for work/index dir setup

There are several write operations on upper fs not covered by mnt_want_write():

• test set/remove OPAQUE xattr
• test create O_TMPFILE
• set ORIGIN xattr in ovl_verify_origin()
• cleanup of index entries in ovl_indexdir_cleanup()

Some of these go way back, but this patch only applies over the v4.14 re-factoring of ovl_fill_super().

For the record, v4.14 above is a typo/braino, I meant to write "the v4.15 re-factoring..."

Cc: stable@vger.kernel.org #v4.14 Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 1a436fa92a04..3387e6d639a5 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -521,10 +521,6 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, bool retried = false; bool locked = false;

•   err = mnt_want_write(mnt);
  

•   if (err)
  

•           goto out_err;
  

•   inode_lock_nested(dir, I_MUTEX_PARENT);
    locked = true;
  
  

@@ -589,7 +585,6 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, goto out_err; } out_unlock:

•   mnt_drop_write(mnt);
    if (locked)
            inode_unlock(dir);
  
  

@@ -930,12 +925,17 @@ static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath)

static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath) {

•   struct vfsmount *mnt = ofs->upper_mnt;
    struct dentry *temp;
    int err;
  
  

•   err = mnt_want_write(mnt);
  

•   if (err)
  

•           return err;
  

•   ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
    if (!ofs->workdir)
  

•           return 0;
  

•           goto out;
  
    /*
     * Upper should support d_type, else whiteouts are visible.  Given
  

@@ -945,7 +945,7 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath) */ err = ovl_check_d_type_supported(workpath); if (err < 0)

•           return err;
  

•           goto out;
  
    /*
     * We allowed this configuration and don't want to break users over
  

@@ -969,6 +969,7 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath) if (err) { ofs->noxattr = true; pr_warn("overlayfs: upper fs does not support xattr.\n");

•           err = 0;
    } else {
            vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
    }
  

@@ -980,7 +981,9 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath) pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n"); }

•   return 0;
  

+out:

•   mnt_drop_write(mnt);
  

•   return err;
  

}

static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) @@ -1027,8 +1030,13 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe, struct path *upperpath) {

•   struct vfsmount *mnt = ofs->upper_mnt;
    int err;
  
  

•   err = mnt_want_write(mnt);
  

•   if (err)
  

•           return err;
  

•   /* Verify lower root is upper root origin */
    err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
                            false, true);
  

@@ -1056,6 +1064,7 @@ static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe, pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");

out:

•   mnt_drop_write(mnt);
    return err;
  

}