Fwd: Objects in ACL cygwin win 10

[Brian Inglis]

On 2020-10-23 21:49, Jim McNamara via Cygwin wrote:
> On Fri, Oct 23, 2020, 10:06 PM Eliot Moss wrote:

>> I have to admit I am not 100% sure what you are asking, but I am careful
>> to grant SYSTEM access so
>> that my backup program can access and save a copy of virtually everything

> Thanks for you and Brian helping me.
> I used icacls cygwin /q /c /t reset

You have to be very careful using icacls and other Windows commands with Cygwin
ACLs as

"ICACLS preserves the canonical ordering of ACE entries:
	Explicit denials
	Explicit grants
	Inherited denials
	Inherited grants"

and Cygwin's POSIX ACLs may or may not obey this canonical order; Windows File
Explorer often does not consider Cygwin ACLs in what it considers canonical
order and requires them to be reordered, which breaks the Cygwin permissions.

Ah, that "NT AUTHORITY/SYSTEM" SID, normally paired with BUILTIN/Administrators,
as users, groups, or both:

$ ls -dl /proc/cygdrive/c/Users/; echo; getfacl /proc/cygdrive/c/Users/; echo;
icacls C:/Users/
drwxr-xr-x+ 1 SYSTEM SYSTEM 0 Apr 13  2020 /proc/cygdrive/c/Users/

# file: /proc/cygdrive/c/Users/
# owner: SYSTEM
# group: SYSTEM
user::rwx
group::r-x
group:Administrators:rwx        #effective:r-x
group:Users:r-x
mask::r-x
other::r-x
default:user::rwx
default:group::---
default:group:Administrators:rwx        #effective:r-x
default:group:Users:r-x
default:mask::r-x
default:other::r-x

C:/Users/ NT AUTHORITY\SYSTEM:(OI)(CI)(F)
          BUILTIN\Administrators:(OI)(CI)(F)
          BUILTIN\Users:(RX)
          BUILTIN\Users:(OI)(CI)(IO)(GR,GE)
          Everyone:(RX)
          Everyone:(OI)(CI)(IO)(GR,GE)

Successfully processed 1 files; Failed processing 0 files

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

This email may be disturbing to some readers as it contains
too much technical detail. Reader discretion is advised.
[Data in binary units and prefixes, physical quantities in SI.]