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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

     FreeBSD 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.  As well as the POSIX.1e rou-
     tines, there are a number of non-portable extensions defined that allow
     for alternative ACL semantics than the POSIX.1e semantics, such as AFS,
     NTFS, Coda, and NWFS semantics.  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 in FreeBSD.

     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_calc_mask()
	     This function is described in acl_calc_mask(3), and may be used
	     to calculate and set the permissions associated with the ACL_MASK
	     entry.

     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_def_file(), acl_delete_def_link_np(), 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_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.

     getfacl(1), setfacl(1), acl_add_perm(3), acl_calc_mask(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)

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.  Discussion of the draft
     continues on the cross-platform POSIX.1e implementation mailing list.  To
     join this list, see the FreeBSD POSIX.1e implementation page for more
     information.

HISTORY

     POSIX.1e support was introduced in FreeBSD 4.0; FreeBSD 5.0 was the first
     version to include a complete ACL implementation based on extended
     attributes for the UFS and UFS2 file systems.

     The getfacl(1) and setfacl(1) utilities describe the user tools that per-
     mit direct manipulation of complete file ACLs.

AUTHORS

     Robert N M Watson

FreeBSD 5.4		       December 18, 2002		   FreeBSD 5.4

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