4.4BSD/usr/share/man/cat3/acl_check.0
ACL_CHECK(3) BSD Programmer's Manual ACL_CHECK(3)
NNAAMMEE
acl_canonicalize_principal, acl_check, acl_exact_match,
acl_add, acl_delete, acl_initialize - access control list
routines
SSYYNNOOPPSSIISS
cccc <<ffiilleess>> --llaaccll --llkkrrbb
##iinncclluuddee <<kkrrbb..hh>>
aaccll__ccaannoonniiccaalliizzee__pprriinncciippaall((pprriinncciippaall,, bbuuff))
cchhaarr **pprriinncciippaall;;
cchhaarr **bbuuff;;
aaccll__cchheecckk((aaccll,, pprriinncciippaall))
cchhaarr **aaccll;;
cchhaarr **pprriinncciippaall;;
aaccll__eexxaacctt__mmaattcchh((aaccll,, pprriinncciippaall))
cchhaarr **aaccll;;
cchhaarr **pprriinncciippaall;;
aaccll__aadddd((aaccll,, pprriinncciippaall))
cchhaarr **aaccll;;
cchhaarr **pprriinncciippaall;;
aaccll__ddeelleettee((aaccll,, pprriinncciippaall))
cchhaarr **aaccll;;
cchhaarr **pprriinncciippaall;;
aaccll__iinniittiiaalliizzee((aaccll__ffiillee,, mmooddee))
cchhaarr **aaccll__ffiillee;;
iinntt mmooddee;;
DDEESSCCRRIIPPTTIIOONN
IInnttrroodduuccttiioonn
An access control list (ACL) is a list of principals,
where each principal is represented by a text string which
cannot contain whitespace. The library allows application
programs to refer to named access control lists to test
membership and to atomically add and delete principals
using a natural and intuitive interface. At present, the
names of access control lists are required to be Unix
filenames, and refer to human-readable Unix files; in the
future, when a networked ACL server is implemented, the
names may refer to a different namespace specific to the
ACL service.
PPrriinncciippaall NNaammeess
Principal names have the form
MIT Project Athena Kerberos Version 4.0 1
ACL_CHECK(3) BSD Programmer's Manual ACL_CHECK(3)
<name>[.<instance>][@<realm>]
e.g.:
asp
asp.root
asp@ATHENA.MIT.EDU
asp.@ATHENA.MIT.EDU
asp.root@ATHENA.MIT.EDU
It is possible for principals to be underspecified. If an
instance is missing, it is assumed to be "". If realm is
missing, it is assumed to be the local realm as determined
by _k_r_b___g_e_t___l_r_e_a_l_m(3). The canonical form contains all of
name, instance, and realm; the acl_add and acl_delete rou-
tines will always leave the file in that form. Note that
the canonical form of asp@ATHENA.MIT.EDU is actually
asp.@ATHENA.MIT.EDU.
RRoouuttiinneess
_a_c_l___c_a_n_o_n_i_c_a_l_i_z_e___p_r_i_n_c_i_p_a_l stores the canonical form of
_p_r_i_n_c_i_p_a_l in _b_u_f. _B_u_f must contain enough space to store
a principal, given the limits on the sizes of name,
instance, and realm specified as ANAME_SZ, INST_SZ, and
REALM_SZ, respectively, in _/_u_s_r_/_i_n_c_l_u_d_e_/_k_r_b_._h.
_a_c_l___c_h_e_c_k returns nonzero if _p_r_i_n_c_i_p_a_l appears in _a_c_l.
Returns 0 if principal does not appear in acl, or if an
error occurs. Canonicalizes principal before checking,
and allows the ACL to contain wildcards. The only sup-
ported wildcards are entries of the form name.*@realm,
*.*@realm, and *.*@*. An asterisk matches any value for
the its component field. For example, "jtkohl.*@*" would
match principal jtkohl, with any instance and any realm.
_a_c_l___e_x_a_c_t___m_a_t_c_h performs like _a_c_l___c_h_e_c_k, but does no
canonicalization or wildcard matching.
_a_c_l___a_d_d atomically adds _p_r_i_n_c_i_p_a_l to _a_c_l. Returns 0 if
successful, nonzero otherwise. It is considered a failure
if _p_r_i_n_c_i_p_a_l is already in _a_c_l. This routine will canoni-
calize _p_r_i_n_c_i_p_a_l, but will treat wildcards literally.
_a_c_l___d_e_l_e_t_e atomically deletes _p_r_i_n_c_i_p_a_l from _a_c_l. Returns
0 if successful, nonzero otherwise. It is considered a
failure if _p_r_i_n_c_i_p_a_l is not already in _a_c_l. This routine
will canonicalize _p_r_i_n_c_i_p_a_l, but will treat wildcards lit-
erally.
_a_c_l___i_n_i_t_i_a_l_i_z_e initializes _a_c_l___f_i_l_e. If the file _a_c_l___f_i_l_e
does not exist, _a_c_l___i_n_i_t_i_a_l_i_z_e creates it with mode _m_o_d_e.
If the file _a_c_l___f_i_l_e exists, _a_c_l___i_n_i_t_i_a_l_i_z_e removes all
members. Returns 0 if successful, nonzero otherwise.
WARNING: Mode argument is likely to change with the
MIT Project Athena Kerberos Version 4.0 2
ACL_CHECK(3) BSD Programmer's Manual ACL_CHECK(3)
eventual introduction of an ACL service.
NNOOTTEESS
In the presence of concurrency, there is a very small
chance that _a_c_l___a_d_d or _a_c_l___d_e_l_e_t_e could report success
even though it would have had no effect. This is a neces-
sary side effect of using lock files for concurrency con-
trol rather than flock(2), which is not supported by NFS.
The current implementation caches ACLs in memory in a
hash-table format for increased efficiency in checking
membership; one effect of the caching scheme is that one
file descriptor will be kept open for each ACL cached, up
to a maximum of 8.
SSEEEE AALLSSOO
kerberos(3), krb_get_lrealm(3)
AAUUTTHHOORR
James Aspnes (MIT Project Athena)
MIT Project Athena Kerberos Version 4.0 3