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ACL(3) BSD Library Functions Manual ACL(3)
NAME
acl -- introduction to the POSIX.1e ACL security API
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <sys/acl.h>
DESCRIPTION
The system permits file systems to export Access Control Lists via the
VFS, and provides a library for userland access to and manipulation of
these ACLs. Not all file systems provide support for ACLs, and some may
require that ACL support be explicitly enabled by the administrator. The
library calls include routines to allocate, duplicate, retrieve, set, and
validate ACLs associated with file objects.
This implementation of the POSIX.1e library differs from the standard in
a number of non-portable ways in order to support the MacOS/Darwin ACL
semantic. Where possible, these differences are implemented using the
mechanisms provided in the standard for such extensions. Where routines
are non-standard, they are suffixed with _np to indicate that they are
not portable.
POSIX.1e describes a set of ACL manipulation routines to manage the con-tents contents
tents of ACLs, as well as their relationships with files; almost all of
these support routines are implemented.
Available functions, sorted by behavior, include:
acl_add_perm()
This function is described in acl_add_perm(3), and may be used to
add permissions to a permission set.
acl_clear_perms()
This function is described in acl_clear_perms(3), and may be used
to clear all permissions from a permission set.
acl_copy_entry()
This function is described in acl_copy_entry(3), and may be used
to copy the contents of an ACL entry.
acl_create_entry()
This function is described in acl_create_entry(3), and may be
used to create an empty entry in an ACL.
acl_delete_fd_np(), acl_delete_file_np(), acl_delete_link_np()
These functions are described in acl_delete(3), and may be used
to delete ACLs from file system objects.
acl_delete_entry()
This function is described in acl_delete_entry(3), and may be
used to delete an entry from an ACL.
acl_delete_perm()
This function is described in acl_delete_perm(3), and may be used
to delete permissions from a permset.
acl_dup()
This function is described in acl_dup(3), and may be used to
duplicate an ACL structure.
acl_free()
This function is described in acl_free(3), and may be used to
free userland working ACL storage.
acl_from_text()
This function is described in acl_from_text(3), and may be used
to convert a text-form ACL into working ACL state, if the ACL has
POSIX.1e semantics.
acl_get_entry()
This function is described in acl_get_entry(3), and may be used
to retrieve a designated ACL entry from an ACL.
acl_get_fd(), acl_get_fd_np(), acl_get_file(), acl_get_link_np()
These functions are described in acl_get(3), and may be used to
retrieve ACLs from file system objects.
acl_get_permset()
This function is described in acl_get_permset(3), and may be used
to retrieve a permset from an ACL entry.
acl_get_qualifier()
This function is described in acl_get_qualifier(3), and may be
used to retrieve the qualifier from an ACL entry.
acl_get_tag_type()
This function is described in acl_get_tag_type(3), and may be
used to retrieve the tag type from an ACL entry.
acl_init()
This function is described in acl_init(3), and may be used to
allocate a fresh (empty) ACL structure.
acl_set_fd(), acl_set_fd_np(), acl_set_file(), acl_set_link_np()
These functions are described in acl_set(3), and may be used to
assign an ACL to a file system object.
acl_set_permset()
This function is described in acl_set_permset(3), and may be used
to set the permissions of an ACL entry from a permset.
acl_set_qualifier()
This function is described in acl_set_qualifier(3), and may be
used to set the qualifier of an ACL.
acl_set_tag_type()
This function is described in acl_set_tag_type(3), and may be
used to set the tag type of an ACL.
acl_to_text()
This function is described in acl_to_text(3), and may be used to
generate a text-form of a POSIX.1e semantics ACL.
acl_valid(), acl_valid_fd_np(), acl_valid_file_np(), acl_valid_link_np()
These functions are described in acl_valid(3), and may be used to
validate an ACL as correct POSIX.1e-semantics, or as appropriate
for a particular file system object regardless of semantics.
Documentation of the internal kernel interfaces backing these calls may
be found in acl(9). The syscalls between the internal interfaces and the
public library routines may change over time, and as such are not docu-mented. documented.
mented. They are not intended to be called directly without going
through the library.
SEE ALSO
ls(1), chmod(1), acl_add_perm(3), acl_clear_perms(3), acl_copy_entry(3),
acl_create_entry(3), acl_delete_entry(3), acl_delete_perm(3), acl_dup(3),
acl_free(3), acl_from_text(3), acl_get(3), acl_get_permset(3),
acl_get_qualifier(3), acl_get_tag_type(3), acl_init(3), acl_set(3),
acl_set_permset(3), acl_set_qualifier(3), acl_set_tag_type(3),
acl_to_text(3), acl_valid(3), posix1e(3), acl(9)
UNSUPPORTED FUNCTIONS
acl_calc_mask(3), acl_delete_def_file()
STANDARDS
POSIX.1e assigns security labels to all objects, extending the security
functionality described in POSIX.1. These additional labels provide
fine-grained discretionary access control, fine-grained capabilities, and
labels necessary for mandatory access control. POSIX.2c describes a set
of userland utilities for manipulating these labels.
POSIX.1e is described in IEEE POSIX.1e draft 17.
HISTORY
This manpage is closely derived from the FreeBSD manpage by Robert N M
Watson
AUTHORS
Michael Smith
Robert N M Watson
BSD December 18, 2002 BSD
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