SMBFS mount's file cannot be made executable

[Takashi Yano]

On Mon, 11 Nov 2024 14:35:55 +0100
Corinna Vinschen wrote:
> On Nov 11 21:19, Takashi Yano via Cygwin wrote:
> > On Mon, 11 Nov 2024 13:03:18 +0100
> > Corinna Vinschen wrote:
> > > On Nov 11 20:40, Takashi Yano via Cygwin wrote:
> > > > On Mon, 11 Nov 2024 20:32:02 +0900
> > > > Takashi Yano via Cygwin <cygwin@cygwin.com> wrote:
> > > > > Even with this patch, the file:
> > > > > 
> > > > > yano $ touch samba_test_file.txt
> > > > > yano $ ls -l samba_test_files.txt
> > > > > -rw-r--r-- 1 yano yano 0 Nov 11 20:25 samba_test_file.txt
> > > > 
> > > > Oops! This was wrong.
> > > > -rw-r--r-- 1 Unknown+User Unix_Group+1000 0 Nov 11 20:25 samba_test_file.txt
> > > 
> > > That's Samba for you.  I applied your patch and created a file
> > > on my share, and the Authenticated Users group was not in the
> > > resulting ACL.  Only user, group, and Everyone.
> > > 
> > > Either way, I don't think this is the right thing to do.  Even if
> > > the group isn't added to the ACL on my machine, it still loks like
> > > a security problem in waiting.
> > 
> > Isn't this DACL here used only for access_check() (NtAccessCheck())?
> > In my environment, the Authenticated Users does not appear in the ACL
> > too.
> 
> Oh, yeah, right, *blush*.
> 
> But it's still not the right thing to do.  You convert the Samba ACL
> to a Windows ACL which gives Authenticated Users full permissions.
> So the check_access() function will return false positives, because
> every authenticated user is in the Authenticated Users group and has
> supposedly FILE_ALL_ACCESS.  Even if the actual function (read, write,
> execute) will fail, the access() function will claim that every
> authenticated user has RWX perms.

Ah, right. I have just confirmed that behaviour...

> AFAICS, the underlying problem is somehow the user mapping.  Did you
> try with username map = /foo/bar?

Yes. However, my user name is 'yano' both in server (Linux) and
client (Windows 10) side. So, I think there is no effect of
'username map'.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>