lib/isc/fsaccess.c

/*
 * Copyright (C) 2000, 2001, 2004, 2005, 2007, 2016, 2017  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/* $Id: fsaccess.c,v 1.10 2007/06/19 23:47:17 tbox Exp $ */

/*! \file
 * \brief
 * This file contains the OS-independent functionality of the API.
 */
#include <isc/fsaccess.h>
#include <isc/print.h>
#include <isc/result.h>
#include <isc/util.h>

/*!
 * Shorthand.  Maybe ISC__FSACCESS_PERMISSIONBITS should not even be in
 * <isc/fsaccess.h>.  Could check consistency with sizeof(isc_fsaccess_t)
 * and the number of bits in each function.
 */
#define STEP        (ISC__FSACCESS_PERMISSIONBITS)
#define GROUP       (STEP)
#define OTHER       (STEP * 2)

void
isc_fsaccess_add(int trustee, int permission, isc_fsaccess_t *access) {
    REQUIRE(trustee <= 0x7);
    REQUIRE(permission <= 0xFF);

    if ((trustee & ISC_FSACCESS_OWNER) != 0)
        *access |= permission;

    if ((trustee & ISC_FSACCESS_GROUP) != 0)
        *access |= (permission << GROUP);

    if ((trustee & ISC_FSACCESS_OTHER) != 0)
        *access |= (permission << OTHER);
}

void
isc_fsaccess_remove(int trustee, int permission, isc_fsaccess_t *access) {
    REQUIRE(trustee <= 0x7);
    REQUIRE(permission <= 0xFF);


    if ((trustee & ISC_FSACCESS_OWNER) != 0)
        *access &= ~permission;

    if ((trustee & ISC_FSACCESS_GROUP) != 0)
        *access &= ~(permission << GROUP);

    if ((trustee & ISC_FSACCESS_OTHER) != 0)
        *access &= ~(permission << OTHER);
}

static isc_result_t
check_bad_bits(isc_fsaccess_t access, isc_boolean_t is_dir) {
    isc_fsaccess_t bits;

    /*
     * Check for disallowed user bits.
     */
    if (is_dir)
        bits = ISC_FSACCESS_READ |
               ISC_FSACCESS_WRITE |
               ISC_FSACCESS_EXECUTE;
    else
        bits = ISC_FSACCESS_CREATECHILD |
               ISC_FSACCESS_ACCESSCHILD |
               ISC_FSACCESS_DELETECHILD |
               ISC_FSACCESS_LISTDIRECTORY;

    /*
     * Set group bad bits.
     */
    bits |= bits << STEP;
    /*
     * Set other bad bits.
     */
    bits |= bits << STEP;

    if ((access & bits) != 0) {
        if (is_dir)
            return (ISC_R_NOTFILE);
        else
            return (ISC_R_NOTDIRECTORY);
    }

    return (ISC_R_SUCCESS);
}