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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 contents 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 permis-sion permission
             sion 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 stor-age. storage.
             age.

     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 seman-tics. semantics.
             tics.

     The syscalls between the internal interfaces and the public library routines 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 capa-bilities, capabilities,
     bilities, 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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