SMB3 Unix extensions

Pavel Shilovsky pavel.shilovsky at
Wed Apr 19 23:41:58 UTC 2017

2017-04-19 10:03 GMT-07:00 Jeremy Allison <jra at>:
> On Tue, Apr 18, 2017 at 10:16:26AM -0500, Steve French wrote:
>> And we do have the slides from SDC.
>> We did reach some conclusions -
>> 1) open with posix create context on root of share will allow us to
>> determined if the server understands posix (so we don't try to send
>> the posix create context on subsequent opens and have it ignored)
>> 2) the capability flags to be returned were discussed at SDC and were
>> pretty simple
>> 3) most features can be done without adding info levels (just with the
>> create context)
>> 4) a new info level (e.g. for fsinfo) was discussed but lower priority
>> and a number was not reserved for new info levels
>> 5) need some info back from Microsoft on opinions about inferring mode
>> from the ACL and also about the 'nfs symlink' (assuming that the other
>> form of symlink reparse point is admin only) vs. simulated symlinks
>> (ala MF symlinks that Apple uses e.g.)
> I've been doing a lot of thinking about SMB2-UNIX-symlinks
> since the recent CVE security patch.
> As SambaXP is only 2 weeks away can we get all the stakeholders
> in a room together and try and hash out a plan to deal with
> the issues with creating UNIX symlinks/reparse points ?
> Some of this is Samba specific, which isn't useful to external
> implementors, but if possible I'd really like to re-use the
> existing SMB2+ reparse mechanisms to implement UNIX extension
> sylinks.

Thanks for the answers. Unfortunately I am not going to SambaXP, so
won't be able to participate in the discussion in person.

I don't understand why to we need to rely on posix create context on a
root of a share if we can use Negotiate phase for this and get posix
capability flags from Negotiate response posix context?

Best regards,
Pavel Shilovsky

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