/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 1995
 *      Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Bill Paul.
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/cdefs.h>
#include <stdlib.h>
#include <rpc/rpc.h>
#include <rpcsvc/yp.h>
#include <rpcsvc/yppasswd.h>
#include <rpcsvc/ypxfrd.h>
#include <sys/types.h>
#include <limits.h>
#include <db.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <paths.h>
#include <errno.h>
#include <sys/param.h>
#include "yp_extern.h"
#ifdef TCP_WRAPPER
#include "tcpd.h"
#endif

static const char *yp_procs[] = {
        /* NIS v1 */
        "ypoldproc_null",
        "ypoldproc_domain",
        "ypoldproc_domain_nonack",
        "ypoldproc_match",
        "ypoldproc_first",
        "ypoldproc_next",
        "ypoldproc_poll",
        "ypoldproc_push",
        "ypoldproc_get",
        "badproc1", /* placeholder */
        "badproc2", /* placeholder */
        "badproc3", /* placeholder */

        /* NIS v2 */
        "ypproc_null",
        "ypproc_domain",
        "ypproc_domain_nonack",
        "ypproc_match",
        "ypproc_first",
        "ypproc_next",
        "ypproc_xfr",
        "ypproc_clear",
        "ypproc_all",
        "ypproc_master",
        "ypproc_order",
        "ypproc_maplist"
};

struct securenet {
        struct in_addr net;
        struct in_addr mask;
        struct securenet *next;
};

static struct securenet *securenets;

#define LINEBUFSZ 1024

#ifdef TCP_WRAPPER
int hosts_ctl(char *, char *, char *, char *);
#endif

/*
 * Read /var/yp/securenets file and initialize the securenets
 * list. If the file doesn't exist, we set up a dummy entry that
 * allows all hosts to connect.
 */
void
load_securenets(void)
{
        FILE *fp;
        char path[MAXPATHLEN + 2];
        char linebuf[1024 + 2];
        struct securenet *tmp;

        /*
         * If securenets is not NULL, we are being called to reload
         * the list; free the existing list before re-reading the
         * securenets file.
         */
        while (securenets) {
                tmp = securenets->next;
                free(securenets);
                securenets = tmp;
        }

        snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir);

        if ((fp = fopen(path, "r")) == NULL) {
                if (errno == ENOENT) {
                        securenets = malloc(sizeof(struct securenet));
                        securenets->net.s_addr = INADDR_ANY;
                        securenets->mask.s_addr = INADDR_ANY;
                        securenets->next = NULL;
                        return;
                } else {
                        yp_error("fopen(%s) failed: %s", path, strerror(errno));
                        exit(1);
                }
        }

        securenets = NULL;

        while (fgets(linebuf, LINEBUFSZ, fp)) {
                char addr1[20], addr2[20];

                if ((linebuf[0] == '#')
                    || (strspn(linebuf, " \t\r\n") == strlen(linebuf)))
                        continue;
                if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) {
                        yp_error("badly formatted securenets entry: %s",
                                                        linebuf);
                        continue;
                }

                tmp = malloc(sizeof(struct securenet));

                if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) {
                        yp_error("badly formatted securenets entry: %s", addr1);
                        free(tmp);
                        continue;
                }

                if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) {
                        yp_error("badly formatted securenets entry: %s", addr2);
                        free(tmp);
                        continue;
                }

                tmp->next = securenets;
                securenets = tmp;
        }

        fclose(fp);

}

/*
 * Access control functions.
 *
 * yp_access() checks the mapname and client host address and watches for
 * the following things:
 *
 * - If the client is referencing one of the master.passwd.* or shadow.* maps,
 *   it must be using a privileged port to make its RPC to us. If it is, then
 *   we can assume that the caller is root and allow the RPC to succeed. If it
 *   isn't access is denied.
 *
 * - The client's IP address is checked against the securenets rules.
 *   There are two kinds of securenets support: the built-in support,
 *   which is very simple and depends on the presence of a
 *   /var/yp/securenets file, and tcp-wrapper support, which requires
 *   Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper
 *   package does not ship with FreeBSD, we use the built-in support
 *   by default. Users can recompile the server with the tcp-wrapper library
 *   if they already have it installed and want to use hosts.allow and
 *   hosts.deny to control access instead of having a separate securenets
 *   file.)
 *
 *   If no /var/yp/securenets file is present, the host access checks
 *   are bypassed and all hosts are allowed to connect.
 *
 * The yp_validdomain() function checks the domain specified by the caller
 * to make sure it's actually served by this server. This is more a sanity
 * check than an a security check, but this seems to be the best place for
 * it.
 */

#ifdef DB_CACHE
int
yp_access(const char *map, const char *domain, const struct svc_req *rqstp)
#else
int
yp_access(const char *map, const struct svc_req *rqstp)
#endif
{
        struct sockaddr_in *rqhost;
        int status_securenets = 0;
#ifdef TCP_WRAPPER
        int status_tcpwrap;
#endif
        static unsigned long oldaddr = 0;
        struct securenet *tmp;
        const char *yp_procedure = NULL;
        char procbuf[50];

        if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) {
                snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu",
                    (unsigned long)rqstp->rq_prog,
                    (unsigned long)rqstp->rq_proc);
                yp_procedure = (char *)&procbuf;
        } else {
                yp_procedure = rqstp->rq_prog == YPPASSWDPROG ?
                "yppasswdprog_update" :
                yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))];
        }

        rqhost = svc_getcaller(rqstp->rq_xprt);

        if (debug) {
                yp_error("procedure %s called from %s:%d", yp_procedure,
                        inet_ntoa(rqhost->sin_addr),
                        ntohs(rqhost->sin_port));
                if (map != NULL)
                        yp_error("client is referencing map \"%s\".", map);
        }

        /* Check the map name if one was supplied. */
        if (map != NULL) {
                if (strchr(map, '/')) {
                        yp_error("embedded slash in map name \"%s\" -- \
possible spoof attempt from %s:%d",
                                map, inet_ntoa(rqhost->sin_addr),
                                ntohs(rqhost->sin_port));
                        return(1);
                }
#ifdef DB_CACHE
                if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) ||
#else
                if ((strstr(map, "master.passwd.") || strstr(map, "shadow.") ||
#endif
                    (rqstp->rq_prog == YPPROG &&
                     rqstp->rq_proc == YPPROC_XFR) ||
                    (rqstp->rq_prog == YPXFRD_FREEBSD_PROG &&
                     rqstp->rq_proc == YPXFRD_GETMAP)) &&
                     ntohs(rqhost->sin_port) >= IPPORT_RESERVED) {
                        yp_error("access to %s denied -- client %s:%d \
not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port));
                        return(1);
                }
        }

#ifdef TCP_WRAPPER
        status_tcpwrap = hosts_ctl("ypserv", STRING_UNKNOWN,
                           inet_ntoa(rqhost->sin_addr), "");
#endif
        tmp = securenets;
        while (tmp) {
                if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr)
                    | tmp->net.s_addr) == rqhost->sin_addr.s_addr) {
                        status_securenets = 1;
                        break;
                }
                tmp = tmp->next;
        }

#ifdef TCP_WRAPPER
        if (status_securenets == 0 || status_tcpwrap == 0) {
#else
        if (status_securenets == 0) {
#endif
        /*
         * One of the following two events occurred:
         *
         * (1) The /var/yp/securenets exists and the remote host does not
         *     match any of the networks specified in it.
         * (2) The hosts.allow file has denied access and TCP_WRAPPER is
         *     defined.
         *
         * In either case deny access.
         */
                if (rqhost->sin_addr.s_addr != oldaddr) {
                        yp_error("connect from %s:%d to procedure %s refused",
                                        inet_ntoa(rqhost->sin_addr),
                                        ntohs(rqhost->sin_port),
                                        yp_procedure);
                        oldaddr = rqhost->sin_addr.s_addr;
                }
                return(1);
        }
        return(0);

}

int
yp_validdomain(const char *domain)
{
        struct stat statbuf;
        char dompath[MAXPATHLEN + 2];

        if (domain == NULL || strstr(domain, "binding") ||
            !strcmp(domain, ".") || !strcmp(domain, "..") ||
            strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN)
                return(1);

        snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain);

        if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode))
                return(1);


        return(0);
}