ACL - Access Control List manipulation

ACL - Access Control List manipulation

Each file has one ACL, containing an ordered list of entries. Each entry refers to a user or group, and grants or denies a set of permissions.

Filesystem object permissions

delete	Delete the item. Deletion can be granted by either this permission on an object or the delete_child right on the containing directory.
readattr	Read an objects basic attributes. This is implicitly granted if the object can be looked up and not explicitly denied.
writeattr	Write an object’s basic attributes.
readextattr	Read extended attributes.
writeextattr	Write extended attributes.
readsecurity	Read an object’s extended security information (ACL).
writesecurity	Write an object’s security information (ownership, mode,ACL).
chown	Change an object’s ownership.

Directory permissions:

list	List entries.
search	Look up files by name.
add_file	Add a file.
add_subdirectory	Add a subdirectory.
delete_child	Delete a contained object. See the file delete permission above.

Non-directory filesystem object permissions:

read	Open for reading.
write	Open for writing.
append	Open for writing, but in a fashion that only allows writes into areas of the file not previously written.
execute	Execute the file as a script or program.

Directory ACL inheritance permissions:

file_inherit	Inherit to files.
directory_inherit	Inherit to directories.
limit_inherit	For subdirectory inheritance; this causes the directory_inherit flag to be cleared, preventing further subdirectories from also inheriting the entry.
only_inherit	The entry is inherited by created items but not considered when processing the ACL.

In cases where a user and a group exist with the same name, the user/group name can be prefixed with "user:" or "group:" in order to specify the type of name.

ACL Examples

Use ls -le to view the effect of all changes.

$ chmod +a "admin allow read,readattr,readextattr,readsecurity" MyDemoDirectory
$ chmod +a "admin allow write" myfile.txt
$ chmod +a "guest deny read" myfile.txt
$ chmod +a "admin allow delete" myfile.txt
$ chmod +ai "others allow read" myfile.txt
$ chmod +a# 2 "others deny read" myfile.txt
$ chmod -a# 1 myfile.txt
$ chmod -a "admin allow write" myfile.txt
$ chmod =a# 1 "admin allow write,chown"

Clear All ACLs:
$ sudo chmod -RN /path/to/folder

Disable Apple Remote Desktop by Revoking execute rights:
$ cd /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/MacOS/
$ sudo ls -l
$ sudo chmod u-s ARDAgent

Exemples acl chmod Mac OS X et extended attributs xattr manipulations

Examples acl chmod Mac OS X

# ls -le

-rw-r--r--+ 1 juser wheel 0 Apr 28 14:06 file1

# chmod +a "admin allow write" file1

# ls -le

-rw-r--r--+ 1 juser wheel 0 Apr 28 14:06 file1

owner: juser

1: admin allow write

# chmod +a "guest deny read" file1

# ls -le

-rw-r--r--+ 1 juser wheel 0 Apr 28 14:06 file1

owner: juser

1: guest deny read

2: admin allow write

# chmod +a "admin allow delete" file1

# ls -le

-rw-r--r--+ 1 juser wheel 0 Apr 28 14:06 file1

owner: juser

1: guest deny read

2: admin allow write,delete

Use the xattr command. You can inspect the extended attributes:

$ xattr s.7z
com.apple.metadata:kMDItemWhereFroms
com.apple.quarantine

and use the -d option to delete one extended attribute:

$ xattr -d com.apple.quarantine s.7z
$ xattr s.7z
com.apple.metadata:kMDItemWhereFroms

you can also use the -c option to remove all extended attributes:

$ xattr -c s.7z
$ xattr s.7z