Displaying streams as xattrs

Andrew Walker awalker at ixsystems.com
Mon May 22 15:36:04 UTC 2023

On Sun, May 21, 2023 at 9:08 PM Steve French <smfrench at gmail.com> wrote:
> Looking through code today (in fs/cifs/xattr.c) I noticed an old
> reference to returning alternate data streams as pseudo-xattrs.
> Although it is possible to list streams via "smbinfo filestreaminfo"
> presumably it is not common (opening streams on remote files from
> Linux is probably not done as commonly as it should be as well).
> Any thoughts about returning alternate data streams via pseudo-xattrs?
> Macs apparently allow this (see e.g.
> https://www.jankyrobotsecurity.com/2018/07/24/accessing-alternate-data-streams-from-a-mac/)
> --
> Thanks,
> Steve

Another issue with exposing ADS as xattr on Linux is that VFS caps max
xattr size at 64 KiB. I've seen MacOS resource forks in the wild with
sizes of up to 3 MiB. FCNTL sounds interesting.


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