[Samba] symlinks loop detection in Samba?

Jeremy Allison jra at samba.org
Tue Jan 19 17:37:59 UTC 2021

On Tue, Jan 19, 2021 at 04:05:47PM +0100, Giuseppe Lo Presti via samba wrote:
>Thanks a lot Ralph,
>To be honest I did not wait for the 40 resolutions to be exceeded, as 
>currently [*] implemented by the kernel, and thought that some loop 
>detection would get triggered earlier (similarly to how e.g. `find -L` 
>is implemented). Indeed I confirm that a Windows client looking to the 
>properties of a shared folder with only one symlink to '.' does see 
>exactly 40 folders, so it's all consistent.
>At the same time, I acknowledge we must keep a loop protection in our 
>filesystem, because in the general case it does take too much time to 
>reach 40 path resolutions when a real folder structure is involved, 
>and a DoS is already happening.
>P.S.: out of curiosity, why did you say "I hate to say, symlinks are 
>fully supported"? :-)

Symlinks are a blight on a perfectly well designed filesystem. Once
the VFS work is finished, expect an epic rant (talk :-) I'm planning
to give :-). Not often I'll say this, but Microsoft got it right
in Windows on this point.

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