Something I wasn't aware of at the time of our prior discussion is
that the Linux NTFS-3g driver already supports Linux extended ACLs
on NTFS. This is discussed at
http://www.tuxera.com/community/ntfs-3g-advanced/ownership-and-permissions/
I explored taking a flash card back and forth between Cygwin
2.4.0-0.18 and a Linux system, testing how each interprets what the
other wrote.
I find they don't seem to interpret each other's per-group and mask
permission bits correctly when creating their Posix interpretation of
an NTFS ACL.
I also find that somehow setting extended ACLs on Linux for a
directory is causing Cygwin to then see that object as a socket, if
I'm reading the below correctly. 'ls' on Cygwin won't descend into
that as it normally would for a directory,
bash: cd: dir_acl: Not a directory
results when attempting to cd into it, etc.
I don't know how common such uses are, but I do use both Cygwin and
Linux on the same flash cards and external disks. If they are both
going to support Posix-style extended ACLs written to NTFS, it'd seem
nice if they could do so in compatible ways.
Nuances re interpreting the below:
- NTFS-3g usually writes full-permission ACEs for SYSTEM and
Administrators. I've patched it on my system to not write those,
for better compatibility with Cygwin 2.3.0 and earlier. (Per the
announcement seeming to indicate those will be ignored starting in
2.4.0, perhaps I'll no longer need such patching.)
- On my Cygwin machine I have distinct SIDs for a user and a group for
each Windows user, simulating the "usergroup" model with ability to
keep distinct permissions for the user and the group. Windows has
the group defined with a _UG suffix, as shows in the icacls outputs;
my /etc/group has them without the _UG suffix, as seen in the
Cygwin commands input and output.
The displays below such as
user:julia_UG:r--
where one might more expect
group:julia:r--
given the commands that created the case seem due to the way I
concocted my NTFS-3g UserMapping file. I have the groups present
with their _UG suffix as users in that file, along with having them
listed without that suffix as groups. I suspect if I remove the
user entry for the group SIDs, these would display as more expected.
I don't think this represents a bug in anything other than my own
UserMapping file.
############ Part 1: On Cygwin
bash 1 23 # uname -a
CYGWIN_NT-6.1-WOW CYGWIN 2.4.0(0.293/5/3) 2016-01-11 20:29 i686 Cygwin
[0] 20:16:03 sally@CYGWIN /e/ACL_PLAY
bash 1 4 # getfacl .
# file: .
# owner: sally
# group: sally
user::rwx
group::---
other:---
default:user::rwx
default:group::---
default:other:---
[0] 20:17:22 sally@CYGWIN /e/ACL_PLAY
bash 1 5 # mkdir written_by_cygwin
[0] 20:17:42 sally@CYGWIN /e/ACL_PLAY
bash 1 6 # cd written_by_cygwin
[0] 20:17:52 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 7 # touch file_simple
[0] 20:18:02 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 8 # touch file_acl
[0] 20:18:08 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 9 # mkdir dir_acl
[0] 20:18:12 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 10 # setfacl -m'g:julia:rwx' file_acl dir_acl
[0] 20:18:29 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 11 # chmod 740 file_acl dir_acl
[0] 20:18:42 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 12 # ls -al
total 0
drwx------+ 1 sally sally 0 Jan 12 20:18 .
drwx------+ 1 sally sally 0 Jan 12 20:17 ..
drwxr-----+ 1 sally sally 0 Jan 12 20:18 dir_acl
-rwxr-----+ 1 sally sally 0 Jan 12 20:18 file_acl
-rw------- 1 sally sally 0 Jan 12 20:18 file_simple
[0] 20:18:45 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 13 # getfacl .
# file: .
# owner: sally
# group: sally
user::rwx
group::---
other:---
default:user::rwx
default:group::---
default:other:---
[0] 20:19:01 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 14 # icacls .
. NULL SID:(DENY)(Rc,S)
CYGWIN\sally:(F)
CYGWIN\sally_ug:(Rc,S,RA)
Everyone:(Rc,S,RA)
NULL SID:(OI)(CI)(IO)(DENY)(Rc,S)
CREATOR OWNER:(OI)(CI)(IO)(F)
CREATOR GROUP:(OI)(CI)(IO)(Rc,S,RA)
Everyone:(OI)(CI)(IO)(Rc,S,RA)
Successfully processed 1 files; Failed processing 0 files
[0] 20:19:04 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 15 # getfacl file_simple
# file: file_simple
# owner: sally
# group: sally
user::rw-
group::---
other:---
[0] 20:20:28 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 16 # icacls file_simple
file_simple NULL SID:(DENY)(Rc,S)
CYGWIN\sally:(R,W,D,WDAC,WO)
CYGWIN\sally_ug:(Rc,S,RA)
Everyone:(Rc,S,RA)
Successfully processed 1 files; Failed processing 0 files
[0] 20:20:37 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 17 # getfacl file_acl
# file: file_acl
# owner: sally
# group: sally
user::rwx
group::---
group:julia:rwx #effective:r--
mask:r--
other:---
[0] 20:20:46 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 18 # icacls file_acl
file_acl NULL SID:(DENY)(Rc,S,X,DC)
CYGWIN\sally:(F)
CYGWIN\julia_ug:(DENY)(W,X,DC)
CYGWIN\sally_ug:(Rc,S,RA)
CYGWIN\julia_ug:(RX,W)
Everyone:(Rc,S,RA)
Successfully processed 1 files; Failed processing 0 files
[0] 20:20:53 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 19 # getfacl dir_acl/
# file: dir_acl/
# owner: sally
# group: sally
user::rwx
group::---
group:julia:rwx #effective:r--
mask:r--
other:---
default:user::rwx
default:group::---
default:other:---
[0] 20:21:16 sally@CYGWIN /e/ACL_PLAY/written_by_cygwin
bash 1 20 # icacls dir_acl/
dir_acl\ NULL SID:(DENY)(Rc,S,X,DC)
CYGWIN\sally:(F)
CYGWIN\julia_ug:(DENY)(W,X,DC)
CYGWIN\sally_ug:(Rc,S,RA)
CYGWIN\julia_ug:(RX,W,DC)
Everyone:(Rc,S,RA)
NULL SID:(OI)(CI)(IO)(DENY)(Rc,S)
CREATOR OWNER:(OI)(CI)(IO)(F)
CREATOR GROUP:(OI)(CI)(IO)(Rc,S,RA)
Everyone:(OI)(CI)(IO)(Rc,S,RA)
Successfully processed 1 files; Failed processing 0 files
############ Part 2: On Linux
bash 1 3 $ uname -a
Linux LINUX 3.19.0-43-generic #49~14.04.1-Ubuntu SMP Thu Dec 31 15:44:49
UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
[0] 20:28:21 sally@LINUX ~
bash 1 1 $ cd /f/ACL_PLAY/
[0] 20:28:26 sally@LINUX /mnt/f/ACL_PLAY
bash 1 2 $ cd written_by_cygwin/
[0] 20:31:49 sally@LINUX /mnt/f/ACL_PLAY/written_by_cygwin
bash 1 16 $ ls -al
total 0
drwx------+ 1 sally sally 0 Jan 12 20:18 .
drwx------+ 1 sally sally 392 Jan 12 20:29 ..
drwxrwx---+ 1 sally sally 0 Jan 12 20:18 dir_acl
-rwxrwx---+ 1 sally sally 0 Jan 12 20:18 file_acl
-rw------- 2 sally sally 0 Jan 12 20:18 file_simple
[0] 20:28:44 sally@LINUX /mnt/f/ACL_PLAY/written_by_cygwin
bash 1 3 $ getfacl . *
# file: .
# owner: sally
# group: sally
user::rwx
group::---
other::---
default:user::rwx
default:group::---
default:other::---
# file: dir_acl
# owner: sally
# group: sally
user::rwx
user:julia_UG:r--
group::---
mask::rwx
other::---
default:user::rwx
default:group::---
default:other::---
# file: file_acl
# owner: sally
# group: sally
user::rwx
user:julia_UG:r--
group::---
mask::rwx
other::---
# file: file_simple
# owner: sally
# group: sally
user::rw-
group::---
other::---
[0] 20:28:51 sally@LINUX /mnt/f/ACL_PLAY/written_by_cygwin
bash 1 4 $ cd ..
[0] 20:40:53 sally@LINUX /mnt/f/ACL_PLAY
bash 1 3 $ mkdir written_by_linux
[0] 20:40:58 sally@LINUX /mnt/f/ACL_PLAY
bash 1 4 $ cd written_by_linux/
[0] 20:41:01 sally@LINUX /mnt/f/ACL_PLAY/written_by_linux
bash 1 5 $ getfacl .
# file: .
# owner: sally
# group: sally
user::rwx
group::---
other::---
default:user::rwx
default:group::---
default:other::---
[0] 20:41:43 sally@LINUX /mnt/f/ACL_PLAY/written_by_linux
bash 1 6 $ touch file_simple
[0] 20:41:51 sally@LINUX /mnt/f/ACL_PLAY/written_by_linux
bash 1 7 $ touch file_acl
[0] 20:42:00 sally@LINUX /mnt/f/ACL_PLAY/written_by_linux
bash 1 8 $ mkdir dir_acl
[0] 20:42:07 sally@LINUX /mnt/f/ACL_PLAY/written_by_linux
bash 1 9 $ setfacl -m'g:julia:rwx' file_acl dir_acl
[0] 20:42:14 sally@LINUX /mnt/f/ACL_PLAY/written_by_linux
bash 1 10 $ chmod 740 file_acl dir_acl
[0] 20:42:22 sally@LINUX /mnt/f/ACL_PLAY/written_by_linux
bash 1 11 $ ls -al
total 0
drwx------+ 1 sally sally 352 Jan 12 20:42 .
drwx------+ 1 sally sally 392 Jan 12 20:40 ..
drwxr-----+ 1 sally sally 0 Jan 12 20:42 dir_acl
-rwxr-----+ 1 sally sally 0 Jan 12 20:42 file_acl
-rw------- 1 sally sally 0 Jan 12 20:41 file_simple
[0] 20:42:30 sally@LINUX /mnt/f/ACL_PLAY/written_by_linux
bash 1 12 $ getfacl . *
# file: .
# owner: sally
# group: sally
user::rwx
group::---
other::---
default:user::rwx
default:group::---
default:other::---
# file: dir_acl
# owner: sally
# group: sally
user::rwx
user:julia_UG:rwx #effective:r--
group::---
mask::r--
other::---
default:user::rwx
default:group::---
default:other::---
# file: file_acl
# owner: sally
# group: sally
user::rwx
user:julia_UG:rwx #effective:r--
group::---
mask::r--
other::---
# file: file_simple
# owner: sally
# group: sally
user::rw-
group::---
other::---
############ Part 3: On Cygwin
[0] 20:47:45 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 34 # ls -al
total 0
drwx------+ 1 sally sally 0 Jan 12 20:42 .
drwx------+ 1 sally sally 0 Jan 12 20:40 ..
srwxr-----+ 1 sally sally 0 Jan 12 20:42 dir_acl
-rwxr-----+ 1 sally sally 0 Jan 12 20:42 file_acl
-rw------- 1 sally sally 0 Jan 12 20:41 file_simple
[0] 20:48:06 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 35 # getfacl .
# file: .
# owner: sally
# group: sally
user::rwx
group::---
other:---
default:user::rwx
default:group::---
default:other:---
[0] 20:48:12 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 36 # icacls .
. Everyone:(OI)(IO)(DENY)(S,X)
CYGWIN\sally:(NP)(F)
Everyone:(NP)(Rc,S,REA,RA)
CYGWIN\sally:(OI)(CI)(IO)(F)
Everyone:(OI)(CI)(IO)(Rc,S,REA,RA)
Successfully processed 1 files; Failed processing 0 files
[0] 20:48:15 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 37 # getfacl file_simple
# file: file_simple
# owner: sally
# group: sally
user::rw-
group::---
other:---
[0] 20:49:24 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 38 # icacls file_simple
file_simple CYGWIN\sally:(NP)(R,W,D,WDAC,WO)
Everyone:(NP)(Rc,S,REA,RA)
Successfully processed 1 files; Failed processing 0 files
[0] 20:50:51 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 40 # getfacl.exe file_acl
# file: file_acl
# owner: sally
# group: sally
user::rwx
group::---
group:julia:r--
mask:r--
other:---
[0] 20:49:50 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 39 # icacls file_acl
file_acl CYGWIN\julia_ug:(NP)(DENY)(W,Rc,WO,X)
CYGWIN\sally:(NP)(M,WDAC,WO)
CYGWIN\julia_ug:(NP)(RX,W)
CYGWIN\sally_ug:(NP)(DENY)(W,Rc,WO,X)
Everyone:(NP)(Rc,S,REA,RA)
Successfully processed 1 files; Failed processing 0 files
[0] 20:51:02 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 41 # getfacl dir_acl
# file: dir_acl
# owner: sally
# group: sally
user::rwx
group::---
group:julia:r--
mask:r--
other:---
default:user::rwx
default:group::---
default:other:---
[0] 20:52:03 sally@CYGWIN /e/ACL_PLAY/written_by_linux
bash 1 42 # icacls dir_acl
dir_acl CYGWIN\julia_ug:(NP)(DENY)(W,Rc,WO,X,DC)
Everyone:(OI)(IO)(DENY)(S,X)
CYGWIN\sally:(NP)(F)
CYGWIN\julia_ug:(NP)(RX,W,DC)
CYGWIN\sally_ug:(NP)(DENY)(W,Rc,WO,X,DC)
Everyone:(NP)(Rc,S,REA,RA)
CYGWIN\sally:(OI)(CI)(IO)(F)
Everyone:(OI)(CI)(IO)(Rc,S,REA,RA)
Successfully processed 1 files; Failed processing 0 files
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