add posixGroup access control via dynacl as an example of how dynacl work

contrib/slapd-modules/acl/README

+Copyright 2005 The OpenLDAP Foundation. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted only as authorized by the OpenLDAP
+Public License.
+
+This directory contains native slapd plugins that implement access rules.
+
+posixgroup.c contains a simple example that implements access control
+based on posixGroup membership, loosely inspired by ITS#3849.  It should
+be made clear that this access control policy does not reflect any
+standard track model of handling access control, and should be 
+essentially viewed as an illustration of the use of the dynamic 
+extension of access control within slapd.
+
+To use the acl-posixgroup plugin, add:
+
+moduleload acl-posixgroup.so
+
+to your slapd configuration file; it requires "nis.schema" to be loaded.
+It is configured using
+
+access to <what>
+	by dynacl/posixGroup[.{exact,expand}]=<dnpat> {<level>|<priv(s)}
+
+The default is "exact"; in case of "expand", "<dnpat>" results from
+the expansion of submatches in the "<what>" portion.  "<level>|<priv(s)>"
+describe the level of privilege this rule can assume.
+
+No Makefile is provided. Use a command line similar to:
+
+gcc -shared -I../../../include -I../../../servers/slapd -Wall -g \
+	-o acl-posixgroup.so posixgroup.c
+
+to compile the posixGroup ACL plugin.
+

contrib/slapd-modules/acl/posixgroup.c

+/* $OpenLDAP$ */
+/*
+ * Copyright 1998-2005 The OpenLDAP Foundation.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+
+#include <portable.h>
+
+#include <ac/string.h>
+#include <slap.h>
+#include <lutil.h>
+
+/* Need dynacl... */
+
+#ifdef SLAP_DYNACL
+
+typedef struct pg_t {
+	slap_style_t		pg_style;
+	struct berval		pg_pat;
+} pg_t;
+
+static ObjectClass		*pg_posixGroup;
+static AttributeDescription	*pg_memberUid;
+static ObjectClass		*pg_posixAccount;
+static AttributeDescription	*pg_uidNumber;
+
+static int pg_dynacl_destroy( void *priv );
+
+static int
+pg_dynacl_parse(
+	const char	*fname,
+	int 		lineno,
+	slap_style_t	style,
+	const char	*pattern,
+	void		**privp )
+{
+	pg_t		*pg;
+	int		rc;
+	const char	*text = NULL;
+	struct berval	pat;
+
+	ber_str2bv( pattern, 0, 0, &pat );
+
+	pg = ch_calloc( 1, sizeof( pg_t ) );
+
+	pg->pg_style = style;
+
+	switch ( pg->pg_style ) {
+	case ACL_STYLE_BASE:
+		rc = dnNormalize( 0, NULL, NULL, &pat, &pg->pg_pat, NULL );
+		if ( rc != LDAP_SUCCESS ) {
+			fprintf( stderr, "%s line %d: posixGroup ACL: "
+				"unable to normalize DN \"%s\".\n",
+				fname, lineno, pattern );
+			goto cleanup;
+		}
+		break;
+
+	case ACL_STYLE_EXPAND:
+		ber_dupbv( &pg->pg_pat, &pat );
+		break;
+
+	default:
+		fprintf( stderr, "%s line %d: posixGroup ACL: "
+			"unsupported style \"%s\".\n",
+			fname, lineno, style_strings[ pg->pg_style ] );
+		goto cleanup;
+	}
+
+	if ( pg_posixGroup == NULL ) {
+		pg_posixGroup = oc_find( "posixGroup" );
+		if ( pg_posixGroup == NULL ) {
+			fprintf( stderr, "%s line %d: posixGroup ACL: "
+				"unable to lookup \"posixGroup\" "
+				"objectClass.\n",
+				fname, lineno );
+			goto cleanup;
+		}
+
+		pg_posixAccount = oc_find( "posixAccount" );
+		if ( pg_posixGroup == NULL ) {
+			fprintf( stderr, "%s line %d: posixGroup ACL: "
+				"unable to lookup \"posixAccount\" "
+				"objectClass.\n",
+				fname, lineno );
+			goto cleanup;
+		}
+
+		rc = slap_str2ad( "memberUid", &pg_memberUid, &text );
+		if ( rc != LDAP_SUCCESS ) {
+			fprintf( stderr, "%s line %d: posixGroup ACL: "
+				"unable to lookup \"memberUid\" "
+				"attributeDescription (%d: %s).\n",
+				fname, lineno, rc, text );
+			goto cleanup;
+		}
+
+		rc = slap_str2ad( "uidNumber", &pg_uidNumber, &text );
+		if ( rc != LDAP_SUCCESS ) {
+			fprintf( stderr, "%s line %d: posixGroup ACL: "
+				"unable to lookup \"uidNumber\" "
+				"attributeDescription (%d: %s).\n",
+				fname, lineno, rc, text );
+			goto cleanup;
+		}
+	}
+
+	*privp = (void *)pg;
+	return 0;
+
+cleanup:
+	(void)pg_dynacl_destroy( (void *)pg );
+
+	return 1;
+}
+
+static int
+pg_dynacl_unparse(
+	void		*priv,
+	struct berval	*bv )
+{
+	pg_t		*pg = (pg_t *)priv;
+	char		*ptr;
+
+	bv->bv_len = STRLENOF( " dynacl/posixGroup.expand=" ) + pg->pg_pat.bv_len;
+	bv->bv_val = ch_malloc( bv->bv_len + 1 );
+
+	ptr = lutil_strcopy( bv->bv_val, " dynacl/posixGroup" );
+
+	switch ( pg->pg_style ) {
+	case ACL_STYLE_BASE:
+		ptr = lutil_strcopy( ptr, ".exact=" );
+		break;
+
+	case ACL_STYLE_EXPAND:
+		ptr = lutil_strcopy( ptr, ".expand=" );
+		break;
+
+	default:
+		assert( 0 );
+	}
+
+	ptr = lutil_strncopy( ptr, pg->pg_pat.bv_val, pg->pg_pat.bv_len );
+	ptr[ 0 ] = '\0';
+
+	bv->bv_len = ptr - bv->bv_val;
+
+	return 0;
+}
+
+static int
+pg_dynacl_mask(
+	void			*priv,
+	struct slap_op		*op,
+	Entry			*target,
+	AttributeDescription	*desc,
+	struct berval		*val,
+	int			nmatch,
+	regmatch_t		*matches,
+	slap_access_t		*grant,
+	slap_access_t		*deny )
+{
+	pg_t		*pg = (pg_t *)priv;
+	Entry		*group = NULL,
+			*user = NULL;
+	int		rc;
+	Backend		*be = op->o_bd,
+			*group_be = NULL,
+			*user_be = NULL;
+	struct berval	group_ndn;
+
+	ACL_INVALIDATE( *deny );
+
+	/* get user */
+	if ( target && dn_match( &target->e_nname, &op->o_ndn ) ) {
+		user = target;
+		rc = LDAP_SUCCESS;
+
+	} else {
+		user_be = op->o_bd = select_backend( &op->o_ndn, 0, 0 );
+		if ( op->o_bd == NULL ) {
+			op->o_bd = be;
+			return 0;
+		}
+		rc = be_entry_get_rw( op, &op->o_ndn, pg_posixAccount, pg_uidNumber, 0, &user );
+	}
+
+	if ( rc != LDAP_SUCCESS || user == NULL ) {
+		op->o_bd = be;
+		return 0;
+	}
+
+	/* get target */
+	if ( pg->pg_style == ACL_STYLE_EXPAND ) {
+		char		buf[ 1024 ];
+		struct berval	bv;
+
+		bv.bv_len = sizeof( buf ) - 1;
+		bv.bv_val = buf;
+
+		if ( acl_string_expand( &bv, &pg->pg_pat,
+				target->e_nname.bv_val,
+				nmatch, matches ) )
+		{
+			goto cleanup;
+		}
+
+		if ( dnNormalize( 0, NULL, NULL, &bv, &group_ndn,
+				op->o_tmpmemctx ) != LDAP_SUCCESS )
+		{
+			/* did not expand to a valid dn */
+			goto cleanup;
+		}
+		
+	} else {
+		group_ndn = pg->pg_pat;
+	}
+
+	if ( target && dn_match( &target->e_nname, &group_ndn ) ) {
+		group = target;
+		rc = LDAP_SUCCESS;
+
+	} else {
+		group_be = op->o_bd = select_backend( &group_ndn, 0, 0 );
+		if ( op->o_bd == NULL ) {
+			goto cleanup;
+		}
+		rc = be_entry_get_rw( op, &group_ndn, pg_posixGroup, pg_memberUid, 0, &group );
+	}
+
+	if ( group_ndn.bv_val != pg->pg_pat.bv_val ) {
+		op->o_tmpfree( group_ndn.bv_val, op->o_tmpmemctx );
+	}
+
+	if ( rc == LDAP_SUCCESS && group != NULL ) {
+		Attribute	*a_uid,
+				*a_member;
+
+		a_uid = attr_find( user->e_attrs, pg_uidNumber);
+		if ( !a_uid || !BER_BVISNULL( &a_uid->a_nvals[ 1 ] ) ) {
+			rc = LDAP_NO_SUCH_ATTRIBUTE;
+
+		} else {
+			a_member = attr_find( group->e_attrs, pg_memberUid );
+			if ( !a_member ) {
+				rc = LDAP_NO_SUCH_ATTRIBUTE;
+
+			} else {
+				rc = value_find_ex( pg_memberUid,
+					SLAP_MR_ATTRIBUTE_VALUE_NORMALIZED_MATCH |
+					SLAP_MR_ASSERTED_VALUE_NORMALIZED_MATCH,
+					a_member->a_nvals, &a_uid->a_nvals[ 0 ],
+					op->o_tmpmemctx );
+			}
+		}
+
+	} else {
+		rc = LDAP_NO_SUCH_OBJECT;
+	}
+
+
+	if ( rc == LDAP_SUCCESS ) {
+		ACL_LVL_ASSIGN_WRITE( *grant );
+	}
+
+cleanup:;
+	if ( group != NULL && group != target ) {
+		op->o_bd = group_be;
+		be_entry_release_r( op, group );
+		op->o_bd = be;
+	}
+
+	if ( user != NULL && user != target ) {
+		op->o_bd = user_be;
+		be_entry_release_r( op, group );
+		op->o_bd = be;
+	}
+
+	return 0;
+}
+
+static int
+pg_dynacl_destroy(
+	void		*priv )
+{
+	pg_t		*pg = (pg_t *)priv;
+
+	if ( pg != NULL ) {
+		if ( !BER_BVISNULL( &pg->pg_pat ) ) {
+			ber_memfree( pg->pg_pat.bv_val );
+		}
+		ch_free( pg );
+	}
+
+	return 0;
+}
+
+static struct slap_dynacl_t pg_dynacl = {
+	"posixGroup",
+	pg_dynacl_parse,
+	pg_dynacl_unparse,
+	pg_dynacl_mask,
+	pg_dynacl_destroy
+};
+
+int
+init_module( int argc, char *argv[] )
+{
+	return slap_dynacl_register( &pg_dynacl );
+}
+
+#endif /* SLAP_DYNACL */