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 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_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.

     The syscalls between the internal interfaces and the public library rou-
     tines may change over time, and as such are not documented.  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)

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