[Samba] symlinks loop detection in Samba?

Giuseppe Lo Presti Giuseppe.LoPresti at cern.ch
Mon Jan 18 13:12:33 UTC 2021

On 18/01/2021 11:58, Ralph Boehme wrote:
> Am 1/18/21 um 11:41 AM schrieb Giuseppe Lo Presti via samba:
>> Following an old thread at [1] I wonder whether there's been any 
>> thought/plan to implement symbolic links loop detection in smbd.
> what do you mean? smbd will detect loops because the kernel tells us 
> about loops with ELOOP.

Well, that's what I hoped, but facts match what Jeremy mentioned at the 

 > the clients will see them [symlinks] as nested directories and request
 > the server to follow them until the OS runs out of recursion
 > depth and returns errors.

So no ELOOP is triggered, and requests just keep piling up from the client.

To reproduce, just create a link to '.' in a shared folder with `follow 
symlinks = yes` and look at its properties from Windows (or copy it 
over, but be ready to clean up the mess afterwards...).

>>  From that thread it seems Jeremy had some ideas, not sure how this 
>> went and whether there's some option I've missed that would do the trick.
> This is still being worked (SMB2 UNIX Extensions that is) -- any help is 
> welcome! :)

Good to know, thanks! :)


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