NAME

setfacl — set ACL information

SYNOPSIS

DESCRIPTION

The setfacl utility sets discretionary access control information on the specified file(s). If no files are specified, or the list consists of the only ‘-’, the file names are taken from the standard input.

The following options are available:

-a position entries

Modify the ACL on the specified files by inserting new ACL entries specified in entries, starting at position position, counting from zero. This option is only applicable to NFSv4 ACLs.

-b

Remove all ACL entries except for the ones synthesized from the file mode - the three mandatory entries in case of POSIX.1e ACL. If the POSIX.1e ACL contains a “mask” entry, the permissions of the “group” entry in the resulting ACL will be set to the permission associated with both the “group” and “mask” entries of the current ACL.

-d

The operations apply to the default ACL entries instead of access ACL entries. Currently only directories may have default ACL's. This option is not applicable to NFSv4 ACLs.

-h

If the target of the operation is a symbolic link, perform the operation on the symbolic link itself, rather than following the link.

-H

If the -R option is specified, symbolic links on the command line are followed and hence unaffected by the command. (Symbolic links encountered during tree traversal are not followed.)

-k

Delete any default ACL entries on the specified files. It is not considered an error if the specified files do not have any default ACL entries. An error will be reported if any of the specified files cannot have a default entry (i.e., non-directories). This option is not applicable to NFSv4 ACLs.

-L

If the -R option is specified, all symbolic links are followed.

-m entries

Modify the ACL on the specified file. New entries will be added, and existing entries will be modified according to the entries argument. For NFSv4 ACLs, it is recommended to use the -a and -x options instead.

-M file

Modify the ACL entries on the specified files by adding new ACL entries and modifying existing ACL entries with the ACL entries specified in the file file. If file is -, the input is taken from stdin.

-n

Do not recalculate the permissions associated with the ACL mask entry. This option is not applicable to NFSv4 ACLs.

-P

If the -R option is specified, no symbolic links are followed. This is the default.

-R

Perform the action recursively on any specified directories. When modifying or adding NFSv4 ACL entries, inheritance flags are applied only to directories.

-x entries | position

If entries is specified, remove the ACL entries specified there from the access or default ACL of the specified files. Otherwise, remove entry at index position, counting from zero.

-X file

Remove the ACL entries specified in the file file from the access or default ACL of the specified files.

The above options are evaluated in the order specified on the command-line.

POSIX.1e ACL ENTRIES

A POSIX.1E ACL entry contains three colon-separated fields: an ACL tag, an ACL qualifier, and discretionary access permissions:

ACL tag

The ACL tag specifies the ACL entry type and consists of one of the following: “user” or ‘u’ specifying the access granted to the owner of the file or a specified user; “group” or ‘g’ specifying the access granted to the file owning group or a specified group; “other” or ‘o’ specifying the access granted to any process that does not match any user or group ACL entry; “mask” or ‘m’ specifying the maximum access granted to any ACL entry except the “user” ACL entry for the file owner and the “other” ACL entry.

ACL qualifier

The ACL qualifier field describes the user or group associated with the ACL entry. It may consist of one of the following: uid or user name, gid or group name, or empty. For “user” ACL entries, an empty field specifies access granted to the file owner. For “group” ACL entries, an empty field specifies access granted to the file owning group. “mask” and “other” ACL entries do not use this field.

access permissions

The access permissions field contains up to one of each of the following: ‘r’, ‘w’, and ‘x’ to set read, write, and execute permissions, respectively. Each of these may be excluded or replaced with a ‘-’ character to indicate no access.

A “mask” ACL entry is required on a file with any ACL entries other than the default “user”, “group”, and “other” ACL entries. If the -n option is not specified and no “mask” ACL entry was specified, the setfacl utility will apply a “mask” ACL entry consisting of the union of the permissions associated with all “group” ACL entries in the resulting ACL.

Traditional POSIX interfaces acting on file system object modes have modified semantics in the presence of POSIX.1e extended ACLs. When a mask entry is present on the access ACL of an object, the mask entry is substituted for the group bits; this occurs in programs such as stat(1) or ls(1). When the mode is modified on an object that has a mask entry, the changes applied to the group bits will actually be applied to the mask entry. These semantics provide for greater application compatibility: applications modifying the mode instead of the ACL will see conservative behavior, limiting the effective rights granted by all of the additional user and group entries; this occurs in programs such as chmod(1).

ACL entries applied from a file using the -M or -X options shall be of the following form: one ACL entry per line, as previously specified; whitespace is ignored; any text after a ‘#’ is ignored (comments).

When POSIX.1e ACL entries are evaluated, the access check algorithm checks the ACL entries in the following order: file owner, “user” ACL entries, file owning group, “group” ACL entries, and “other” ACL entry.

Multiple ACL entries specified on the command line are separated by commas.

It is possible for files and directories to inherit ACL entries from their parent directory. This is accomplished through the use of the default ACL. It should be noted that before you can specify a default ACL, the mandatory ACL entries for user, group, other and mask must be set. For more details see the examples below. Default ACLs can be created by using -d.

NFSv4 ACL ENTRIES

An NFSv4 ACL entry contains four or five colon-separated fields: an ACL tag, an ACL qualifier (only for “user” and “group” tags), discretionary access permissions, ACL inheritance flags, and ACL type:

ACL tag

The ACL tag specifies the ACL entry type and consists of one of the following: “user” or ‘u’ specifying the access granted to the specified user; “group” or ‘g’ specifying the access granted to the specified group; “owner@” specifying the access granted to the owner of the file; “group@” specifying the access granted to the file owning group; “everyone@” specifying everyone. Note that “everyone@” is not the same as traditional Unix “other” - it means, literally, everyone, including file owner and owning group.

ACL qualifier

The ACL qualifier field describes the user or group associated with the ACL entry. It may consist of one of the following: uid or user name, or gid or group name. In entries whose tag type is one of “owner@”, “group@”, or “everyone@”, this field is omitted altogether, including the trailing comma.

access permissions

Access permissions may be specified in either short or long form. Short and long forms may not be mixed. Permissions in long form are separated by the ‘/’ character; in short form, they are concatenated together. Valid permissions are:

Short

Long

r

read_data

w

write_data

x

execute

p

append_data

D

delete_child

d

delete

a

read_attributes

A

write_attributes

R

read_xattr

W

write_xattr

c

read_acl

C

write_acl

o

write_owner

s

synchronize

In addition, the following permission sets may be used:

Set

Permissions

full_set

all permissions, as shown above

modify_set

all permissions except write_acl and write_owner

read_set

read_data, read_attributes, read_xattr and read_acl

write_set

write_data, append_data, write_attributes and write_xattr

ACL inheritance flags

Inheritance flags may be specified in either short or long form. Short and long forms may not be mixed. Access flags in long form are separated by the ‘/’ character; in short form, they are concatenated together. Valid inheritance flags are:

Short

Long

f

file_inherit

d

dir_inherit

i

inherit_only

n

no_propagate

I

inherited

Other than the "inherited" flag, inheritance flags may be only set on directories.

ACL type

The ACL type field is either “allow” or “deny”.

ACL entries applied from a file using the -M or -X options shall be of the following form: one ACL entry per line, as previously specified; whitespace is ignored; any text after a ‘#’ is ignored (comments).

NFSv4 ACL entries are evaluated in their visible order.

Multiple ACL entries specified on the command line are separated by commas.

Note that the file owner is always granted the read_acl, write_acl, read_attributes, and write_attributes permissions, even if the ACL would deny it.

EXIT STATUS

The setfacl utility exits 0 on success, and >0 if an error occurs.

EXAMPLES

The first command sets the mandatory elements of the POSIX.1e default ACL. The second command specifies that users in group admins can have read, write, and execute permissions for directory named "dir". It should be noted that any files or directories created underneath "dir" will inherit these default ACLs upon creation.

Sets read, write, and execute permissions for the file owner's POSIX.1e ACL entry and read and write permissions for group mail on file.

Semantically equal to the example above, but for NFSv4 ACL.

Sets/updates the ACL entries contained in file1 on file2.

Remove the group mail POSIX.1e ACL entry containing read/write permissions from file.

Remove the first entry from the NFSv4 ACL from file.

Remove all “access” ACL entries except for the three required from file.

Copy ACL entries from file1 to file2.

SEE ALSO

getfacl(1), acl(3), getextattr(8), setextattr(8), acl(9), extattr(9)

STANDARDS

The setfacl utility is expected to be IEEE Std 1003.2c compliant.

HISTORY

Extended Attribute and Access Control List support was developed as part of the TrustedBSD Project and introduced in FreeBSD 5.0. NFSv4 ACL support was introduced in FreeBSD 8.1.

AUTHORS

The setfacl utility was written by Chris D. Faulhaber <jedgar@fxp.org>. NFSv4 ACL support was implemented by Edward Tomasz Napierala <trasz@FreeBSD.org>.