[Samba] /proc/self open fails with proc_owner Was: Time-machine replies with 17: File Exists

[Ralph Boehme]

Am 5/4/21 um 6:34 AM schrieb Jorgen Lundman via samba:
> ...
> 
> create_file: NT_STATUS_ACCESS_DENIED
> 
> Running truss on smb to find out what actually goes wrong, it appears
> to be:
> 
> streams_xattr_open called for /proc/self/fd/11 with flags 0x81 
> 6036/1:         write(1, " s t r e a m s _ x a t t".., 63)      = 63 
> 6036/1:         open("/proc/self/fd/11", O_WRONLY|O_NONBLOCK)
> Err#13 EACCES [proc_owner] catia_fetch_fsp_post_next: Called from
> [catia_openat] 6036/1:         write(1, " c a t i a _ f e t c h _"..,
> 54)      = 54
> 
> Which is presumably OmniOS related, in that it is trying to open the
> /proc/self/ as a different uid to the process.

Can you elaborate on that please so I can better understand why the
open() fails with EACCES?

Particularly I don't understand what you mean with "... trying to open
the /proc/self/ as a different uid to the process."

Typically Samba would to this open() syscall impersonating the
authenticated user (ie set effective uid, gid and auxiliary groups set
to the values of the underlying OS account).

> Can I tell Smb to not use /proc/self, and instead use regular paths?

No currently there's no way to disable this other by configuration.
There's a general runtime check that verifies /proc/self/fd is usable by
calling stat() on /proc/self/fd/0 (iirc), looks like this is not fine
grained enough to cover stupid OSes.

Cheers!
-slow

-- 
Ralph Boehme, Samba Team                https://samba.org/
Samba Developer, SerNet GmbH   https://sernet.de/en/samba/
GPG-Fingerprint   FAE2C6088A24252051C559E4AA1E9B7126399E46

-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature
Type: application/pgp-signature
Size: 840 bytes
Desc: OpenPGP digital signature
URL: <http://lists.samba.org/pipermail/samba/attachments/20210504/5a8ea759/OpenPGP_signature.sig>