[Samba] Random EINVAL when opening files with SMB3 POSIX extensions enabled

Andrew Gunnerson
Thu, 28 Nov 2024 20:46:45 -0000

Thanks for the replies!

On Thu, Nov 28, 2024, at 04:34, Rowland Penny via samba
wrote:
> I do not use the SMB3 Unix extensions, but perhaps you may not be
> either, have you tried replacing 'server min protocol = SMB2'
(which is
> the default anyway) with 'server min protocol = SMB3' ?

I took a packet capture and do see the the client making POSIX extension
requests, like SMB2_FILE_POSIX_INFO.

On Thu, Nov 28, 2024, at 04:53, Ralph Boehme wrote:
> can you grab a network trace when it happens?

Sure thing! I disabled SMB encryption first since it seemed to make the pcaps
useless.

1. pcap when running `cat <file>`, which fails with EINVAL:


https://files.pub.chiller3.com/issues/samba/posix_extensions/2024-11-28/posix_enabled_broken.pcap

2. pcap when running `ls $(dirname <file>); cat <file>`, which seems
to
   temporarily (but consistently) allow the file to be opened for a short time:


https://files.pub.chiller3.com/issues/samba/posix_extensions/2024-11-28/posix_enabled_working.pcap

3. pcap when running `cat <file>` with the extensions disabled, which
always
   works:


https://files.pub.chiller3.com/issues/samba/posix_extensions/2024-11-28/posix_disabled_working.pcap

> Beware that SMB3 POSIX Extensions are still under active development and
> I would recommend not using them in production right now because of bugs
> in Samba and cifs.ko.

That's good to know. In my case, I'm mostly playing around with things
on my
personal systems and don't care if anything breaks or data gets corrupted.
Happy
to help test things!

-Andrew