HardenedBSD/sbin/dhclient/dispatch.c

/*	$OpenBSD: dispatch.c,v 1.31 2004/09/21 04:07:03 david Exp $	*/

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright 2004 Henning Brauer <henning@openbsd.org>
 * Copyright (c) 1995, 1996, 1997, 1998, 1999
 * The Internet Software Consortium.   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 Internet Software Consortium 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 INTERNET SOFTWARE CONSORTIUM 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 INTERNET SOFTWARE CONSORTIUM 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.
 *
 * This software has been written for the Internet Software Consortium
 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
 * Enterprises.  To learn more about the Internet Software Consortium,
 * see ``http://www.vix.com/isc''.  To learn more about Vixie
 * Enterprises, see ``http://www.vix.com''.
 */

#include <sys/cdefs.h>
#include "dhcpd.h"
#include "privsep.h"

#include <sys/ioctl.h>

#include <assert.h>
#include <net/if_media.h>
#include <ifaddrs.h>
#include <poll.h>

/* Assert that pointer p is aligned to at least align bytes */
#define assert_aligned(p, align) assert((((uintptr_t)p) & ((align) - 1)) == 0)

static struct protocol *protocols;
static const struct timespec timespec_intmax_ms = {
	.tv_sec = INT_MAX / 1000,
	.tv_nsec = (INT_MAX % 1000) * 1000000
};
static struct timeout *timeouts;
static struct timeout *free_timeouts;
static int interfaces_invalidated;
void (*bootp_packet_handler)(struct interface_info *,
    struct dhcp_packet *, int, unsigned int,
    struct iaddr, struct hardware *);

static int interface_status(struct interface_info *ifinfo);

/*
 * Use getifaddrs() to get a list of all the attached interfaces.  For
 * each interface that's of type INET and not the loopback interface,
 * register that interface with the network I/O software, figure out
 * what subnet it's on, and add it to the list of interfaces.
 */
void
discover_interfaces(struct interface_info *iface)
{
	struct ifaddrs *ifap, *ifa;
	struct ifreq *tif;

	if (getifaddrs(&ifap) != 0)
		error("getifaddrs failed");

	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
		if ((ifa->ifa_flags & IFF_LOOPBACK) ||
		    (ifa->ifa_flags & IFF_POINTOPOINT) ||
		    (!(ifa->ifa_flags & IFF_UP)))
			continue;

		if (strcmp(iface->name, ifa->ifa_name))
			continue;

		/*
		 * If we have the capability, extract link information
		 * and record it in a linked list.
		 */
		if (ifa->ifa_addr->sa_family == AF_LINK) {
			struct sockaddr_dl *foo;

			/* 
			 * The implementation of getifaddrs should guarantee
			 * this alignment
			 */
			assert_aligned(ifa->ifa_addr,
				       _Alignof(struct sockaddr_dl));
#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wcast-align"
#endif
			foo = (struct sockaddr_dl *)ifa->ifa_addr;
#ifdef __clang__
#pragma clang diagnostic pop
#endif

			iface->index = foo->sdl_index;
			iface->hw_address.hlen = foo->sdl_alen;
			iface->hw_address.htype = HTYPE_ETHER; /* XXX */
			memcpy(iface->hw_address.haddr,
			    LLADDR(foo), foo->sdl_alen);
		}
		if (!iface->ifp) {
			if ((tif = calloc(1, sizeof(struct ifreq))) == NULL)
				error("no space to remember ifp");
			strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
			iface->ifp = tif;
		}

	}

	if (!iface->ifp)
		error("%s: not found", iface->name);

	/* Register the interface... */
	if_register_receive(iface);
	if_register_send(iface);
	add_protocol(iface->name, iface->rfdesc, got_one, iface);
	freeifaddrs(ifap);
}

void
reinitialize_interfaces(void)
{
	interfaces_invalidated = 1;
}

/*
 * Wait for packets to come in using poll().  When a packet comes in,
 * call receive_packet to receive the packet and possibly strip hardware
 * addressing information from it, and then call through the
 * bootp_packet_handler hook to try to do something with it.
 */
void
dispatch(void)
{
	int count, live_interfaces, i, to_msec, nfds = 0;
	struct protocol *l;
	struct pollfd *fds;
	struct timespec howlong;
	time_now.tv_sec = cur_time;
	time_now.tv_nsec = 0;

	for (l = protocols; l; l = l->next)
		nfds++;

	fds = malloc(nfds * sizeof(struct pollfd));
	if (fds == NULL)
		error("Can't allocate poll structures.");

	do {
		/*
		 * Call any expired timeouts, and then if there's still
		 * a timeout registered, time out the select call then.
		 */
another:
		if (timeouts) {
			struct timeout *t;

			if (timespeccmp(&timeouts->when, &time_now, <=)) {
				t = timeouts;
				timeouts = timeouts->next;
				(*(t->func))(t->what);
				t->next = free_timeouts;
				free_timeouts = t;
				goto another;
			}

			/*
			 * Figure timeout in milliseconds, and check for
			 * potential overflow, so we can cram into an
			 * int for poll, while not polling with a
			 * negative timeout and blocking indefinitely.
			 */
			timespecsub(&timeouts->when, &time_now, &howlong);
			if (timespeccmp(&howlong, &timespec_intmax_ms, >))
				howlong = timespec_intmax_ms;
			to_msec = howlong.tv_sec * 1000 + howlong.tv_nsec / 1000000;
		} else
			to_msec = -1;

		/* Set up the descriptors to be polled. */
		live_interfaces = 0;
		for (i = 0, l = protocols; l; l = l->next) {
			struct interface_info *ip = l->local;

			if (ip == NULL || ip->dead)
				continue;
			fds[i].fd = l->fd;
			fds[i].events = POLLIN;
			fds[i].revents = 0;
			i++;
			if (l->handler == got_one)
				live_interfaces++;
		}
		if (live_interfaces == 0)
			error("No live interfaces to poll on - exiting.");

		/* Wait for a packet or a timeout... XXX */
		count = poll(fds, nfds, to_msec);

		/* Not likely to be transitory... */
		if (count == -1) {
			if (errno == EAGAIN || errno == EINTR) {
				clock_gettime(CLOCK_MONOTONIC, &time_now);
				cur_time = time_now.tv_sec;
				continue;
			} else
				error("poll: %m");
		}

		/* Get the current time... */
		clock_gettime(CLOCK_MONOTONIC, &time_now);
		cur_time = time_now.tv_sec;

		i = 0;
		for (l = protocols; l; l = l->next) {
			struct interface_info *ip;
			ip = l->local;
			if ((fds[i].revents & (POLLIN | POLLHUP))) {
				fds[i].revents = 0;
				if (ip && (l->handler != got_one ||
				    !ip->dead))
					(*(l->handler))(l);
				if (interfaces_invalidated)
					break;
			}
			i++;
		}
		interfaces_invalidated = 0;
	} while (1);
}


void
got_one(struct protocol *l)
{
	struct sockaddr_in from;
	struct hardware hfrom;
	struct iaddr ifrom;
	ssize_t result;
	union {
		/*
		 * Packet input buffer.  Must be as large as largest
		 * possible MTU.
		 */
		unsigned char packbuf[4095];
		struct dhcp_packet packet;
	} u;
	struct interface_info *ip = l->local;

	if ((result = receive_packet(ip, u.packbuf, sizeof(u), &from,
	    &hfrom)) == -1) {
		warning("receive_packet failed on %s: %s", ip->name,
		    strerror(errno));
		ip->errors++;
		if ((!interface_status(ip)) ||
		    (ip->noifmedia && ip->errors > 20)) {
			/* our interface has gone away. */
			warning("Interface %s no longer appears valid.",
			    ip->name);
			ip->dead = 1;
			interfaces_invalidated = 1;
			close(l->fd);
			remove_protocol(l);
			free(ip);
		}
		return;
	}
	if (result == 0)
		return;

	if (bootp_packet_handler) {
		ifrom.len = 4;
		memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);

		(*bootp_packet_handler)(ip, &u.packet, result,
		    from.sin_port, ifrom, &hfrom);
	}
}

int
interface_status(struct interface_info *ifinfo)
{
	char *ifname = ifinfo->name;
	int ifsock = ifinfo->rfdesc;
	struct ifreq ifr;
	struct ifmediareq ifmr;

	/* get interface flags */
	memset(&ifr, 0, sizeof(ifr));
	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
	if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
		cap_syslog(capsyslog, LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m",
		    ifname);
		goto inactive;
	}

	/*
	 * if one of UP and RUNNING flags is dropped,
	 * the interface is not active.
	 */
	if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
		goto inactive;

	/* Next, check carrier on the interface, if possible */
	if (ifinfo->noifmedia)
		goto active;
	memset(&ifmr, 0, sizeof(ifmr));
	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
	if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
		if (errno != EINVAL) {
			cap_syslog(capsyslog, LOG_DEBUG,
			    "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
			ifinfo->noifmedia = 1;
			goto active;
		}
		/*
		 * EINVAL (or ENOTTY) simply means that the interface
		 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
		 */
		ifinfo->noifmedia = 1;
		goto active;
	}
	if (ifmr.ifm_status & IFM_AVALID) {
		switch (ifmr.ifm_active & IFM_NMASK) {
		case IFM_ETHER:
		case IFM_IEEE80211:
			if (ifmr.ifm_status & IFM_ACTIVE)
				goto active;
			else
				goto inactive;
			break;
		default:
			goto inactive;
		}
	}
inactive:
	return (0);
active:
	return (1);
}

void
add_timeout(time_t when_s, void (*where)(void *), void *what)
{
	struct timespec when = { .tv_sec = when_s, .tv_nsec = 0 };
	add_timeout_timespec(when, where, what);
}

void
add_timeout_timespec(struct timespec when, void (*where)(void *), void *what)
{
	struct timeout *t, *q;

	/* See if this timeout supersedes an existing timeout. */
	t = NULL;
	for (q = timeouts; q; q = q->next) {
		if (q->func == where && q->what == what) {
			if (t)
				t->next = q->next;
			else
				timeouts = q->next;
			break;
		}
		t = q;
	}

	/* If we didn't supersede a timeout, allocate a timeout
	   structure now. */
	if (!q) {
		if (free_timeouts) {
			q = free_timeouts;
			free_timeouts = q->next;
			q->func = where;
			q->what = what;
		} else {
			q = malloc(sizeof(struct timeout));
			if (!q)
				error("Can't allocate timeout structure!");
			q->func = where;
			q->what = what;
		}
	}

	q->when = when;

	/* Now sort this timeout into the timeout list. */

	/* Beginning of list? */
	if (!timeouts || timespeccmp(&timeouts->when, &q->when, >)) {
		q->next = timeouts;
		timeouts = q;
		return;
	}

	/* Middle of list? */
	for (t = timeouts; t->next; t = t->next) {
		if (timespeccmp(&t->next->when, &q->when, >)) {
			q->next = t->next;
			t->next = q;
			return;
		}
	}

	/* End of list. */
	t->next = q;
	q->next = NULL;
}

void
cancel_timeout(void (*where)(void *), void *what)
{
	struct timeout *t, *q;

	/* Look for this timeout on the list, and unlink it if we find it. */
	t = NULL;
	for (q = timeouts; q; q = q->next) {
		if (q->func == where && q->what == what) {
			if (t)
				t->next = q->next;
			else
				timeouts = q->next;
			break;
		}
		t = q;
	}

	/* If we found the timeout, put it on the free list. */
	if (q) {
		q->next = free_timeouts;
		free_timeouts = q;
	}
}

/* Add a protocol to the list of protocols... */
void
add_protocol(const char *name, int fd, void (*handler)(struct protocol *),
    void *local)
{
	struct protocol *p;

	p = malloc(sizeof(*p));
	if (!p)
		error("can't allocate protocol struct for %s", name);

	p->fd = fd;
	p->handler = handler;
	p->local = local;
	p->next = protocols;
	protocols = p;
}

void
remove_protocol(struct protocol *proto)
{
	struct protocol *p, *prev;

	for (p = protocols, prev = NULL; p != NULL; prev = p, p = p->next) {
		if (p == proto) {
			if (prev == NULL)
				protocols = p->next;
			else
				prev->next = p->next;
			free(p);
			break;
		}
	}
}

int
interface_link_status(char *ifname)
{
	struct ifmediareq ifmr;
	int sock;

	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
		error("Can't create socket");

	memset(&ifmr, 0, sizeof(ifmr));
	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
	if (ioctl(sock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
		/* EINVAL -> link state unknown. treat as active */
		if (errno != EINVAL)
			cap_syslog(capsyslog, LOG_DEBUG,
			    "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
		close(sock);
		return (1);
	}
	close(sock);

	if (ifmr.ifm_status & IFM_AVALID) {
		switch (ifmr.ifm_active & IFM_NMASK) {
		case IFM_ETHER:
		case IFM_IEEE80211:
			if (ifmr.ifm_status & IFM_ACTIVE)
				return (1);
			else
				return (0);
		}
	}
	return (1);
}

void
interface_set_mtu_unpriv(int privfd, u_int16_t mtu)
{
	struct imsg_hdr hdr;
	struct buf *buf;
	int errs = 0;

	hdr.code = IMSG_SET_INTERFACE_MTU;
	hdr.len = sizeof(hdr) +
		sizeof(u_int16_t);

	if ((buf = buf_open(hdr.len)) == NULL)
		error("buf_open: %m");

	errs += buf_add(buf, &hdr, sizeof(hdr));
	errs += buf_add(buf, &mtu, sizeof(mtu));
	if (errs)
		error("buf_add: %m");
	
	if (buf_close(privfd, buf) == -1)
		error("buf_close: %m");
}

void
interface_set_mtu_priv(char *ifname, u_int16_t mtu)
{
	struct ifreq ifr;
	int sock;
	u_int16_t old_mtu;

	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
		error("Can't create socket");

	memset(&ifr, 0, sizeof(ifr));
	old_mtu = 0;

	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));

	if (ioctl(sock, SIOCGIFMTU, (caddr_t)&ifr) == -1)
		warning("SIOCGIFMTU failed (%s): %s", ifname,
			strerror(errno));
	else
		old_mtu = ifr.ifr_mtu;

	if (mtu != old_mtu) {
		ifr.ifr_mtu = mtu;

		if (ioctl(sock, SIOCSIFMTU, &ifr) == -1)
			warning("SIOCSIFMTU failed (%d): %s", mtu,
				strerror(errno));
	}

	close(sock);
}