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Re: File permissions when using ACLs
- From: Andrey Repin <anrdaemon at yandex dot ru>
- To: Charles Plager <cplager at gmail dot com>, cygwin at cygwin dot com
- Date: Tue, 11 Mar 2014 16:30:47 +0400
- Subject: Re: File permissions when using ACLs
- Authentication-results: sourceware.org; auth=none
- References: <CAKfFMLQe3L3q_qJ-=07KiCQwraqQYP3jbB-8fohZaH9-7PWnSg at mail dot gmail dot com>
- Reply-to: cygwin at cygwin dot com
Greetings, Charles Plager!
> Short version: When writing to network drives (and probably local
> ones) as Cygwin is setup by default, we see the permissions being set
> using the ACLs where "creator owner" is given "full control" and
> "creator" group are given "read/execute", but by setting "special
> permissions" instead of just having "full control" or "read/execute"
> Why does it not just set "full control" or "read/execute"?
Cygwin by default mimicking POSIX permission set.
If this behavior is undesirable, You can work around it by letting operating
system control the ACL.
Modify cygdrive entry in /etc/fstab to include noacl option.
Then any files accessed outside direct/implied mounts will have permissions
controlled by OS.
> Long, slightly different version: When the above permissions get set,
> we sometimes see (sometimes = 1 file in a million or less) a file that
> ends up with no permissions. Owner loses permissions, admin loses
> permissions and so far, IT has only been able to make the file go away
> by reformatting the drive.
> When we tell Cygwin not to use ACLs (adding the following in
> /etc/fstab), this does not seem to happen (in 100 million or so files
> none /cygdrive/ cygdrive binary,posix=0,user,noacl 0 0
> This only seems to happen for files created by Cygwin with the ACL
> permissions (although, to be fair, without Cygwin, I don't know that
> anybody is generating as many files). I'm assuming it isn't Cygwin,
> per say, but rather something that interacts with how Cygwin setup the
> permissions (and given the rarity of the problem it is difficult to
> diagnose more thoroughly.
> So, to sum up:
> * Why use special permissions and not default settings when using ACLs?
> * Anybody else experience files that lose all permissions? Any
> suggestions on resetting the file (short of reformatting the drive)?
> * Any other hints/insights that might be useful here?
> p.s. We see this behavior for Cygwin 1.7.9 and beyond. In 1.7.5, it
> doesn't appear as if the ACLs are used and it acts as if "noacl" is
Andrey Repin (firstname.lastname@example.org) 11.03.2014, <16:08>
Sorry for my terrible english...
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