ACL_CHECK(3) BSD Programmer's Manual ACL_CHECK(3)
acl_canonicalize_principal, acl_check, acl_exact_match,
acl_add, acl_delete, acl_initialize - access control list
S
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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
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\bNa
\bam
\bme
\bes
\bs
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>]
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 _
\bk_
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\bb_
\b__
\bg_
\be_
\bt_
\b__
\bl_
\br_
\be_
\ba_
\bl_
\bm(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
R
\bRo
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\but
\bti
\bin
\bne
\bes
\bs
_
\ba_
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\bl_
\b__
\bc_
\ba_
\bn_
\bo_
\bn_
\bi_
\bc_
\ba_
\bl_
\bi_
\bz_
\be_
\b__
\bp_
\br_
\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl stores the canonical form of
_
\bp_
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\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl in _
\bb_
\bu_
\bf. _
\bB_
\bu_
\bf 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 _
\b/_
\bu_
\bs_
\br_
\b/_
\bi_
\bn_
\bc_
\bl_
\bu_
\bd_
\be_
\b/_
\bk_
\br_
\bb_
\b._
\bh.
_
\ba_
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\bl_
\b__
\bc_
\bh_
\be_
\bc_
\bk returns nonzero if _
\bp_
\br_
\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl appears in _
\ba_
\bc_
\bl.
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
its component field. For example, "jtkohl.*@*" would
match principal jtkohl, with any instance and any realm.
_
\ba_
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\bl_
\b__
\be_
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\ba_
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\b__
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\ba_
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\bh performs like _
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\b__
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canonicalization or wildcard matching.
_
\ba_
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\b__
\ba_
\bd_
\bd atomically adds _
\bp_
\br_
\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl to _
\ba_
\bc_
\bl. Returns 0 if
successful, nonzero otherwise. It is considered a failure
if _
\bp_
\br_
\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl is already in _
\ba_
\bc_
\bl. This routine will canoni-
calize _
\bp_
\br_
\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl, but will treat wildcards literally.
_
\ba_
\bc_
\bl_
\b__
\bd_
\be_
\bl_
\be_
\bt_
\be atomically deletes _
\bp_
\br_
\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl from _
\ba_
\bc_
\bl. Returns
0 if successful, nonzero otherwise. It is considered a
failure if _
\bp_
\br_
\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl is not already in _
\ba_
\bc_
\bl. This routine
will canonicalize _
\bp_
\br_
\bi_
\bn_
\bc_
\bi_
\bp_
\ba_
\bl, but will treat wildcards lit-
_
\ba_
\bc_
\bl_
\b__
\bi_
\bn_
\bi_
\bt_
\bi_
\ba_
\bl_
\bi_
\bz_
\be initializes _
\ba_
\bc_
\bl_
\b__
\bf_
\bi_
\bl_
\be. If the file _
\ba_
\bc_
\bl_
\b__
\bf_
\bi_
\bl_
\be
does not exist, _
\ba_
\bc_
\bl_
\b__
\bi_
\bn_
\bi_
\bt_
\bi_
\ba_
\bl_
\bi_
\bz_
\be creates it with mode _
\bm_
\bo_
\bd_
\be.
If the file _
\ba_
\bc_
\bl_
\b__
\bf_
\bi_
\bl_
\be exists, _
\ba_
\bc_
\bl_
\b__
\bi_
\bn_
\bi_
\bt_
\bi_
\ba_
\bl_
\bi_
\bz_
\be 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.
In the presence of concurrency, there is a very small
chance that _
\ba_
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\bl_
\b__
\ba_
\bd_
\bd or _
\ba_
\bc_
\bl_
\b__
\bd_
\be_
\bl_
\be_
\bt_
\be 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
S
\bSE
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\bE A
\bAL
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\bO
kerberos(3), krb_get_lrealm(3)
James Aspnes (MIT Project Athena)
MIT Project Athena Kerberos Version 4.0 3
projects / unix-history / blob