smb2.session.reauth4: UID/GID to use as anonymous user when modifying DACL

[Stefan Metzmacher]

Hi Xavi,

>>> At the same time, I can also see that getuid()/getgid() returns 0/0 and
>>> geteuid()/getegid() also returns 0/0. Does the default plugin use
>>> uid/gid 0/0 while performing this operation?
>>>
>>> I have the following questions
>>> 1) What are we testing for with this smbtorture test?
>>> 2) Is the anonymous user allowed to modify the DACL of the file as done
>>> in the test? This would obviously lead to access denied errors as we
>>> see currently.
>>
>> It checks the reauthentication has no effect on open file handles
>> only on new file handles. After the SMB2 Create only fsp->access_mask
>> matters for access checking.
>>
>>> 3) What uid/gid should be set when performing this action as the
>>> anonymous user?
>>
>> Maybe you need to remember the low level token at open time
>> and use that.
>>
> 
> I'm not sure if this will work in all cases. When the acl_xattr vfs module
> is used, the Windows ACLs are stored in "security.NTACL". To correctly set
> this xattr, the process needs to become root on a kernel mounted filesystem
> because the kernel doesn't allow a regular user to modify that xattr, even
> if the user has permissions to modify the file.
> 
> If a share uses a vfs module instead of a kernel mount to export the
> filesystem, and that filesystem also requires root privileges to modify the
> "security" namespace, then using the cached permissions at the time of
> opening the file won't be enough.
> 
> I think that the unix token should be kept consistent with the effective
> owner of the process at all times to avoid this problem or similar ones.

We have get_current_utok(), which refects become_root().
Currently that can be used instead of handle->conn->session_info->unix_token.

metze