freebsd-dev/sys/netinet/ip_divert.c
Bill Fenner 4d3ffc9841 Renumber IPPROTO_DIVERT out of the range of valid IP protocol numbers.
This allows socket() to return an error when the kernel is not built
with IPDIVERT, and doesn't prevent future applications from using the
"borrowed" IP protocol number.  The sysctl net.inet.raw.olddiverterror
controls whether opening a socket with the "borrowed" IP protocol
fails with an accompanying kernel printf; this code should last only a
couple of releases.

Approved by:	re
2002-10-29 16:46:13 +00:00

569 lines
15 KiB
C

/*
* Copyright (c) 1982, 1986, 1988, 1993
* The Regents of the University of California. 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 the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
*
* $FreeBSD$
*/
#include "opt_inet.h"
#include "opt_ipfw.h"
#include "opt_ipdivert.h"
#include "opt_ipsec.h"
#include "opt_mac.h"
#ifndef INET
#error "IPDIVERT requires INET."
#endif
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mac.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/signalvar.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <vm/uma.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
/*
* Divert sockets
*/
/*
* Allocate enough space to hold a full IP packet
*/
#define DIVSNDQ (65536 + 100)
#define DIVRCVQ (65536 + 100)
/*
* Divert sockets work in conjunction with ipfw, see the divert(4)
* manpage for features.
* Internally, packets selected by ipfw in ip_input() or ip_output(),
* and never diverted before, are passed to the input queue of the
* divert socket with a given 'divert_port' number (as specified in
* the matching ipfw rule), and they are tagged with a 16 bit cookie
* (representing the rule number of the matching ipfw rule), which
* is passed to process reading from the socket.
*
* Packets written to the divert socket are again tagged with a cookie
* (usually the same as above) and a destination address.
* If the destination address is INADDR_ANY then the packet is
* treated as outgoing and sent to ip_output(), otherwise it is
* treated as incoming and sent to ip_input().
* In both cases, the packet is tagged with the cookie.
*
* On reinjection, processing in ip_input() and ip_output()
* will be exactly the same as for the original packet, except that
* ipfw processing will start at the rule number after the one
* written in the cookie (so, tagging a packet with a cookie of 0
* will cause it to be effectively considered as a standard packet).
*/
/* Internal variables */
static struct inpcbhead divcb;
static struct inpcbinfo divcbinfo;
static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */
static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */
/* Optimization: have this preinitialized */
static struct sockaddr_in divsrc = { sizeof(divsrc), AF_INET };
/*
* Initialize divert connection block queue.
*/
void
div_init(void)
{
INP_INFO_LOCK_INIT(&divcbinfo, "div");
LIST_INIT(&divcb);
divcbinfo.listhead = &divcb;
/*
* XXX We don't use the hash list for divert IP, but it's easier
* to allocate a one entry hash list than it is to check all
* over the place for hashbase == NULL.
*/
divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask);
divcbinfo.porthashbase = hashinit(1, M_PCB, &divcbinfo.porthashmask);
divcbinfo.ipi_zone = uma_zcreate("divcb", sizeof(struct inpcb),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
uma_zone_set_max(divcbinfo.ipi_zone, maxsockets);
}
/*
* IPPROTO_DIVERT is not in the real IP protocol number space; this
* function should never be called. Just in case, drop any packets.
*/
void
div_input(struct mbuf *m, int off)
{
ipstat.ips_noproto++;
m_freem(m);
}
/*
* Divert a packet by passing it up to the divert socket at port 'port'.
*
* Setup generic address and protocol structures for div_input routine,
* then pass them along with mbuf chain.
*/
void
divert_packet(struct mbuf *m, int incoming, int port, int rule)
{
struct ip *ip;
struct inpcb *inp;
struct socket *sa;
u_int16_t nport;
/* Sanity check */
KASSERT(port != 0, ("%s: port=0", __func__));
divsrc.sin_port = rule; /* record matching rule */
/* Assure header */
if (m->m_len < sizeof(struct ip) &&
(m = m_pullup(m, sizeof(struct ip))) == 0)
return;
ip = mtod(m, struct ip *);
/*
* Record receive interface address, if any.
* But only for incoming packets.
*/
divsrc.sin_addr.s_addr = 0;
if (incoming) {
struct ifaddr *ifa;
/* Sanity check */
KASSERT((m->m_flags & M_PKTHDR), ("%s: !PKTHDR", __func__));
/* Find IP address for receive interface */
TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
if (ifa->ifa_addr == NULL)
continue;
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
divsrc.sin_addr =
((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
break;
}
}
/*
* Record the incoming interface name whenever we have one.
*/
bzero(&divsrc.sin_zero, sizeof(divsrc.sin_zero));
if (m->m_pkthdr.rcvif) {
/*
* Hide the actual interface name in there in the
* sin_zero array. XXX This needs to be moved to a
* different sockaddr type for divert, e.g.
* sockaddr_div with multiple fields like
* sockaddr_dl. Presently we have only 7 bytes
* but that will do for now as most interfaces
* are 4 or less + 2 or less bytes for unit.
* There is probably a faster way of doing this,
* possibly taking it from the sockaddr_dl on the iface.
* This solves the problem of a P2P link and a LAN interface
* having the same address, which can result in the wrong
* interface being assigned to the packet when fed back
* into the divert socket. Theoretically if the daemon saves
* and re-uses the sockaddr_in as suggested in the man pages,
* this iface name will come along for the ride.
* (see div_output for the other half of this.)
*/
snprintf(divsrc.sin_zero, sizeof(divsrc.sin_zero),
"%s%d", m->m_pkthdr.rcvif->if_name,
m->m_pkthdr.rcvif->if_unit);
}
/* Put packet on socket queue, if any */
sa = NULL;
nport = htons((u_int16_t)port);
LIST_FOREACH(inp, &divcb, inp_list) {
if (inp->inp_lport == nport)
sa = inp->inp_socket;
}
if (sa) {
if (sbappendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc,
m, (struct mbuf *)0) == 0)
m_freem(m);
else
sorwakeup(sa);
} else {
m_freem(m);
ipstat.ips_noproto++;
ipstat.ips_delivered--;
}
}
/*
* Deliver packet back into the IP processing machinery.
*
* If no address specified, or address is 0.0.0.0, send to ip_output();
* otherwise, send to ip_input() and mark as having been received on
* the interface with that address.
*/
static int
div_output(struct socket *so, struct mbuf *m,
struct sockaddr_in *sin, struct mbuf *control)
{
int error = 0;
struct m_hdr divert_tag;
/*
* Prepare the tag for divert info. Note that a packet
* with a 0 tag in mh_data is effectively untagged,
* so we could optimize that case.
*/
divert_tag.mh_type = MT_TAG;
divert_tag.mh_flags = PACKET_TAG_DIVERT;
divert_tag.mh_next = m;
divert_tag.mh_data = 0; /* the matching rule # */
m->m_pkthdr.rcvif = NULL; /* XXX is it necessary ? */
#ifdef MAC
mac_create_mbuf_from_socket(so, m);
#endif
if (control)
m_freem(control); /* XXX */
/* Loopback avoidance and state recovery */
if (sin) {
int i;
divert_tag.mh_data = (caddr_t)(uintptr_t)sin->sin_port;
/*
* Find receive interface with the given name, stuffed
* (if it exists) in the sin_zero[] field.
* The name is user supplied data so don't trust its size
* or that it is zero terminated.
*/
for (i = 0; sin->sin_zero[i] && i < sizeof(sin->sin_zero); i++)
;
if ( i > 0 && i < sizeof(sin->sin_zero))
m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
}
/* Reinject packet into the system as incoming or outgoing */
if (!sin || sin->sin_addr.s_addr == 0) {
struct inpcb *const inp = sotoinpcb(so);
struct ip *const ip = mtod(m, struct ip *);
/*
* Don't allow both user specified and setsockopt options,
* and don't allow packet length sizes that will crash
*/
if (((ip->ip_hl != (sizeof (*ip) >> 2)) && inp->inp_options) ||
((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
error = EINVAL;
goto cantsend;
}
/* Convert fields to host order for ip_output() */
ip->ip_len = ntohs(ip->ip_len);
ip->ip_off = ntohs(ip->ip_off);
/* Send packet to output processing */
ipstat.ips_rawout++; /* XXX */
error = ip_output((struct mbuf *)&divert_tag,
inp->inp_options, &inp->inp_route,
(so->so_options & SO_DONTROUTE) |
IP_ALLOWBROADCAST | IP_RAWOUTPUT,
inp->inp_moptions, NULL);
} else {
if (m->m_pkthdr.rcvif == NULL) {
/*
* No luck with the name, check by IP address.
* Clear the port and the ifname to make sure
* there are no distractions for ifa_ifwithaddr.
*/
struct ifaddr *ifa;
bzero(sin->sin_zero, sizeof(sin->sin_zero));
sin->sin_port = 0;
ifa = ifa_ifwithaddr((struct sockaddr *) sin);
if (ifa == NULL) {
error = EADDRNOTAVAIL;
goto cantsend;
}
m->m_pkthdr.rcvif = ifa->ifa_ifp;
}
/* Send packet to input processing */
ip_input((struct mbuf *)&divert_tag);
}
return error;
cantsend:
m_freem(m);
return error;
}
static int
div_attach(struct socket *so, int proto, struct thread *td)
{
struct inpcb *inp;
int error, s;
inp = sotoinpcb(so);
if (inp)
panic("div_attach");
if (td && (error = suser(td)) != 0)
return error;
error = soreserve(so, div_sendspace, div_recvspace);
if (error)
return error;
s = splnet();
error = in_pcballoc(so, &divcbinfo, td);
splx(s);
if (error)
return error;
inp = (struct inpcb *)so->so_pcb;
inp->inp_ip_p = proto;
inp->inp_vflag |= INP_IPV4;
inp->inp_flags |= INP_HDRINCL;
/* The socket is always "connected" because
we always know "where" to send the packet */
so->so_state |= SS_ISCONNECTED;
return 0;
}
static int
div_detach(struct socket *so)
{
struct inpcb *inp;
inp = sotoinpcb(so);
if (inp == 0)
panic("div_detach");
in_pcbdetach(inp);
return 0;
}
static int
div_abort(struct socket *so)
{
soisdisconnected(so);
return div_detach(so);
}
static int
div_disconnect(struct socket *so)
{
if ((so->so_state & SS_ISCONNECTED) == 0)
return ENOTCONN;
return div_abort(so);
}
static int
div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
{
struct inpcb *inp;
int s;
int error;
s = splnet();
inp = sotoinpcb(so);
/* in_pcbbind assumes that nam is a sockaddr_in
* and in_pcbbind requires a valid address. Since divert
* sockets don't we need to make sure the address is
* filled in properly.
* XXX -- divert should not be abusing in_pcbind
* and should probably have its own family.
*/
if (nam->sa_family != AF_INET)
error = EAFNOSUPPORT;
else {
((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
error = in_pcbbind(inp, nam, td);
}
splx(s);
return error;
}
static int
div_shutdown(struct socket *so)
{
socantsendmore(so);
return 0;
}
static int
div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
struct mbuf *control, struct thread *td)
{
/* Packet must have a header (but that's about it) */
if (m->m_len < sizeof (struct ip) &&
(m = m_pullup(m, sizeof (struct ip))) == 0) {
ipstat.ips_toosmall++;
m_freem(m);
return EINVAL;
}
/* Send packet */
return div_output(so, m, (struct sockaddr_in *)nam, control);
}
static int
div_pcblist(SYSCTL_HANDLER_ARGS)
{
int error, i, n, s;
struct inpcb *inp, **inp_list;
inp_gen_t gencnt;
struct xinpgen xig;
/*
* The process of preparing the TCB list is too time-consuming and
* resource-intensive to repeat twice on every request.
*/
if (req->oldptr == 0) {
n = divcbinfo.ipi_count;
req->oldidx = 2 * (sizeof xig)
+ (n + n/8) * sizeof(struct xinpcb);
return 0;
}
if (req->newptr != 0)
return EPERM;
/*
* OK, now we're committed to doing something.
*/
s = splnet();
gencnt = divcbinfo.ipi_gencnt;
n = divcbinfo.ipi_count;
splx(s);
xig.xig_len = sizeof xig;
xig.xig_count = n;
xig.xig_gen = gencnt;
xig.xig_sogen = so_gencnt;
error = SYSCTL_OUT(req, &xig, sizeof xig);
if (error)
return error;
inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
if (inp_list == 0)
return ENOMEM;
s = splnet();
for (inp = LIST_FIRST(divcbinfo.listhead), i = 0; inp && i < n;
inp = LIST_NEXT(inp, inp_list)) {
if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->td, inp))
inp_list[i++] = inp;
}
splx(s);
n = i;
error = 0;
for (i = 0; i < n; i++) {
inp = inp_list[i];
if (inp->inp_gencnt <= gencnt) {
struct xinpcb xi;
xi.xi_len = sizeof xi;
/* XXX should avoid extra copy */
bcopy(inp, &xi.xi_inp, sizeof *inp);
if (inp->inp_socket)
sotoxsocket(inp->inp_socket, &xi.xi_socket);
error = SYSCTL_OUT(req, &xi, sizeof xi);
}
}
if (!error) {
/*
* Give the user an updated idea of our state.
* If the generation differs from what we told
* her before, she knows that something happened
* while we were processing this request, and it
* might be necessary to retry.
*/
s = splnet();
xig.xig_gen = divcbinfo.ipi_gencnt;
xig.xig_sogen = so_gencnt;
xig.xig_count = divcbinfo.ipi_count;
splx(s);
error = SYSCTL_OUT(req, &xig, sizeof xig);
}
free(inp_list, M_TEMP);
return error;
}
/*
* This is the wrapper function for in_setsockaddr. We just pass down
* the pcbinfo for in_setpeeraddr to lock.
*/
static int
div_sockaddr(struct socket *so, struct sockaddr **nam)
{
return (in_setsockaddr(so, nam, &divcbinfo));
}
/*
* This is the wrapper function for in_setpeeraddr. We just pass down
* the pcbinfo for in_setpeeraddr to lock.
*/
static int
div_peeraddr(struct socket *so, struct sockaddr **nam)
{
return (in_setpeeraddr(so, nam, &divcbinfo));
}
SYSCTL_DECL(_net_inet_divert);
SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, 0, 0,
div_pcblist, "S,xinpcb", "List of active divert sockets");
struct pr_usrreqs div_usrreqs = {
div_abort, pru_accept_notsupp, div_attach, div_bind,
pru_connect_notsupp, pru_connect2_notsupp, in_control, div_detach,
div_disconnect, pru_listen_notsupp, div_peeraddr, pru_rcvd_notsupp,
pru_rcvoob_notsupp, div_send, pru_sense_null, div_shutdown,
div_sockaddr, sosend, soreceive, sopoll
};