freebsd-nq/usr.sbin/rtsold/rtsock.c
Mark Johnston 04e9edb544 Capsicumize rtsol(8) and rtsold(8).
These programs parse ND6 Router Advertisement messages; rtsold(8) has
required an SA, SA-14:20.rtsold, for a bug in this code.  Thus, they
are good candidates for sandboxing.

The approach taken is to run the main executable in capability mode
and use Casper services to provide functionality that cannot be
implemented within the sandbox.  In particular, several custom services
were required.

- A Casper service is used to send Router Solicitation messages on a
  raw ICMP6 socket.  Initially I took the approach of creating a
  socket for each interface upon startup, and connect(2)ing it to
  the all-routers multicast group for the interface.  This permits
  the use of sendmsg(2) in capability mode, but only works if the
  interface's link is up when rtsol(d) starts.  So, instead, the
  rtsold.sendmsg service is used to transmit RS messages on behalf
  of the main process.  One could alternately define a service
  which simply creates and connects a socket for each destination
  address, and returns the socket to the sandboxed process.  However,
  to implement rtsold's -m option we also need to read the ND6 default
  router list, and this cannot be done in capability mode.
- rtsold may execute resolvconf(8) in response to RDNSS and DNSSL
  options in received RA messages.  A Casper service is used to
  fork and exec resolvconf(8), and to reap the child process.
- A service is used to determine whether a given interface's
  link-local address is useable (i.e., not duplicated or undergoing
  DAD).  This information is supplied by getifaddrs(3), which reads
  a sysctl not available in capability mode.  The SIOCGIFCONF socket
  ioctl provides equivalent information and can be used in capability
  mode, but I decided against it for now because of some limitations
  of that interface.

In addition to these new services, cap_syslog(3) is used to send
messages to syslogd.

Reviewed by:	oshogbo
Tested by:	bz (previous versions)
MFC after:	2 months
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17572
2019-01-05 16:05:39 +00:00

178 lines
4.6 KiB
C

/* $KAME: rtsock.c,v 1.3 2000/10/10 08:46:45 itojun Exp $ */
/* $FreeBSD$ */
/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (C) 2000 WIDE Project.
* 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. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 THE PROJECT 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/param.h>
#include <sys/capsicum.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <net/if.h>
#include <net/route.h>
#include <net/if_dl.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <capsicum_helpers.h>
#include <time.h>
#include <unistd.h>
#include <stdio.h>
#include <stddef.h>
#include <err.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>
#include "rtsold.h"
static int rtsock_input_ifannounce(int, struct rt_msghdr *, char *);
static struct {
u_char type;
size_t minlen;
int (*func)(int, struct rt_msghdr *, char *);
} rtsock_dispatch[] = {
{ RTM_IFANNOUNCE, sizeof(struct if_announcemsghdr),
rtsock_input_ifannounce },
{ 0, 0, NULL },
};
int
rtsock_open(void)
{
cap_rights_t rights;
int error, s;
s = socket(PF_ROUTE, SOCK_RAW, 0);
if (s < 0)
return (s);
cap_rights_init(&rights, CAP_EVENT, CAP_READ);
if (caph_rights_limit(s, &rights) != 0) {
error = errno;
(void)close(s);
errno = errno;
return (-1);
}
return (s);
}
int
rtsock_input(int s)
{
ssize_t n;
char msg[2048];
char *lim, *next;
struct rt_msghdr *rtm;
int idx;
ssize_t len;
int ret = 0;
const ssize_t lenlim =
offsetof(struct rt_msghdr, rtm_msglen) + sizeof(rtm->rtm_msglen);
n = read(s, msg, sizeof(msg));
lim = msg + n;
for (next = msg; next < lim; next += len) {
rtm = (struct rt_msghdr *)(void *)next;
if (lim - next < lenlim)
break;
len = rtm->rtm_msglen;
if (len < lenlim)
break;
if (dflag > 1) {
warnmsg(LOG_INFO, __func__,
"rtmsg type %d, len=%lu", rtm->rtm_type,
(u_long)len);
}
for (idx = 0; rtsock_dispatch[idx].func; idx++) {
if (rtm->rtm_type != rtsock_dispatch[idx].type)
continue;
if (rtm->rtm_msglen < rtsock_dispatch[idx].minlen) {
warnmsg(LOG_INFO, __func__,
"rtmsg type %d too short!", rtm->rtm_type);
continue;
}
ret = (*rtsock_dispatch[idx].func)(s, rtm, lim);
break;
}
}
return (ret);
}
static int
rtsock_input_ifannounce(int s __unused, struct rt_msghdr *rtm, char *lim)
{
struct if_announcemsghdr *ifan;
struct ifinfo *ifi;
ifan = (struct if_announcemsghdr *)rtm;
if ((char *)(ifan + 1) > lim)
return (-1);
switch (ifan->ifan_what) {
case IFAN_ARRIVAL:
/*
* XXX for NetBSD 1.5, interface index will monotonically be
* increased as new pcmcia card gets inserted.
* we may be able to do a name-based interface match,
* and call ifreconfig() to enable the interface again.
*/
warnmsg(LOG_INFO, __func__,
"interface %s inserted", ifan->ifan_name);
break;
case IFAN_DEPARTURE:
warnmsg(LOG_WARNING, __func__,
"interface %s removed", ifan->ifan_name);
ifi = find_ifinfo(ifan->ifan_index);
if (ifi) {
if (dflag > 1) {
warnmsg(LOG_INFO, __func__,
"bring interface %s to DOWN state",
ifan->ifan_name);
}
ifi->state = IFS_DOWN;
}
break;
}
return (0);
}