1/*-
2 * Copyright (c) 2003 Andre Oppermann, Internet Business Solutions AG
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote
14 * products derived from this software without specific prior written
15 * permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30/*
31 * ip_fastforward gets its speed from processing the forwarded packet to
32 * completion (if_output on the other side) without any queues or netisr's.
33 * The receiving interface DMAs the packet into memory, the upper half of
34 * driver calls ip_fastforward, we do our routing table lookup and directly
35 * send it off to the outgoing interface, which DMAs the packet to the
36 * network card. The only part of the packet we touch with the CPU is the
37 * IP header (unless there are complex firewall rules touching other parts
38 * of the packet, but that is up to you). We are essentially limited by bus
39 * bandwidth and how fast the network card/driver can set up receives and
40 * transmits.
41 *
42 * We handle basic errors, IP header errors, checksum errors,
43 * destination unreachable, fragmentation and fragmentation needed and
44 * report them via ICMP to the sender.
45 *
46 * Else if something is not pure IPv4 unicast forwarding we fall back to
47 * the normal ip_input processing path. We should only be called from
48 * interfaces connected to the outside world.
49 *
50 * Firewalling is fully supported including divert, ipfw fwd and ipfilter
51 * ipnat and address rewrite.
52 *
53 * IPSEC is not supported if this host is a tunnel broker. IPSEC is
54 * supported for connections to/from local host.
55 *
56 * We try to do the least expensive (in CPU ops) checks and operations
57 * first to catch junk with as little overhead as possible.
58 *
59 * We take full advantage of hardware support for IP checksum and
60 * fragmentation offloading.
61 *
62 * We don't do ICMP redirect in the fast forwarding path. I have had my own
63 * cases where two core routers with Zebra routing suite would send millions
64 * ICMP redirects to connected hosts if the destination router was not the
65 * default gateway. In one case it was filling the routing table of a host
66 * with approximately 300.000 cloned redirect entries until it ran out of
67 * kernel memory. However the networking code proved very robust and it didn't
68 * crash or fail in other ways.
69 */
70
71/*
72 * Many thanks to Matt Thomas of NetBSD for basic structure of ip_flow.c which
73 * is being followed here.
74 */
75
76#include <sys/cdefs.h>
| 1/*-
2 * Copyright (c) 2003 Andre Oppermann, Internet Business Solutions AG
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote
14 * products derived from this software without specific prior written
15 * permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30/*
31 * ip_fastforward gets its speed from processing the forwarded packet to
32 * completion (if_output on the other side) without any queues or netisr's.
33 * The receiving interface DMAs the packet into memory, the upper half of
34 * driver calls ip_fastforward, we do our routing table lookup and directly
35 * send it off to the outgoing interface, which DMAs the packet to the
36 * network card. The only part of the packet we touch with the CPU is the
37 * IP header (unless there are complex firewall rules touching other parts
38 * of the packet, but that is up to you). We are essentially limited by bus
39 * bandwidth and how fast the network card/driver can set up receives and
40 * transmits.
41 *
42 * We handle basic errors, IP header errors, checksum errors,
43 * destination unreachable, fragmentation and fragmentation needed and
44 * report them via ICMP to the sender.
45 *
46 * Else if something is not pure IPv4 unicast forwarding we fall back to
47 * the normal ip_input processing path. We should only be called from
48 * interfaces connected to the outside world.
49 *
50 * Firewalling is fully supported including divert, ipfw fwd and ipfilter
51 * ipnat and address rewrite.
52 *
53 * IPSEC is not supported if this host is a tunnel broker. IPSEC is
54 * supported for connections to/from local host.
55 *
56 * We try to do the least expensive (in CPU ops) checks and operations
57 * first to catch junk with as little overhead as possible.
58 *
59 * We take full advantage of hardware support for IP checksum and
60 * fragmentation offloading.
61 *
62 * We don't do ICMP redirect in the fast forwarding path. I have had my own
63 * cases where two core routers with Zebra routing suite would send millions
64 * ICMP redirects to connected hosts if the destination router was not the
65 * default gateway. In one case it was filling the routing table of a host
66 * with approximately 300.000 cloned redirect entries until it ran out of
67 * kernel memory. However the networking code proved very robust and it didn't
68 * crash or fail in other ways.
69 */
70
71/*
72 * Many thanks to Matt Thomas of NetBSD for basic structure of ip_flow.c which
73 * is being followed here.
74 */
75
76#include <sys/cdefs.h>
|
77__FBSDID("$FreeBSD: head/sys/netinet/ip_fastfwd.c 258541 2013-11-25 07:38:45Z attilio $");
| 77__FBSDID("$FreeBSD: head/sys/netinet/ip_fastfwd.c 262763 2014-03-05 01:17:47Z glebius $");
|
78
79#include "opt_ipfw.h"
80#include "opt_ipstealth.h"
81
82#include <sys/param.h>
83#include <sys/systm.h>
84#include <sys/kernel.h>
85#include <sys/malloc.h>
86#include <sys/mbuf.h>
87#include <sys/protosw.h>
88#include <sys/sdt.h>
89#include <sys/socket.h>
90#include <sys/sysctl.h>
91
92#include <net/pfil.h>
93#include <net/if.h>
94#include <net/if_types.h>
95#include <net/if_var.h>
96#include <net/if_dl.h>
97#include <net/route.h>
98#include <net/vnet.h>
99
100#include <netinet/in.h>
101#include <netinet/in_kdtrace.h>
102#include <netinet/in_systm.h>
103#include <netinet/in_var.h>
104#include <netinet/ip.h>
105#include <netinet/ip_var.h>
106#include <netinet/ip_icmp.h>
107#include <netinet/ip_options.h>
108
109#include <machine/in_cksum.h>
110
111static VNET_DEFINE(int, ipfastforward_active);
112#define V_ipfastforward_active VNET(ipfastforward_active)
113
114SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, fastforwarding, CTLFLAG_RW,
115 &VNET_NAME(ipfastforward_active), 0, "Enable fast IP forwarding");
116
117static struct sockaddr_in *
118ip_findroute(struct route *ro, struct in_addr dest, struct mbuf *m)
119{
120 struct sockaddr_in *dst;
121 struct rtentry *rt;
122
123 /*
124 * Find route to destination.
125 */
126 bzero(ro, sizeof(*ro));
127 dst = (struct sockaddr_in *)&ro->ro_dst;
128 dst->sin_family = AF_INET;
129 dst->sin_len = sizeof(*dst);
130 dst->sin_addr.s_addr = dest.s_addr;
131 in_rtalloc_ign(ro, 0, M_GETFIB(m));
132
133 /*
134 * Route there and interface still up?
135 */
136 rt = ro->ro_rt;
137 if (rt && (rt->rt_flags & RTF_UP) &&
138 (rt->rt_ifp->if_flags & IFF_UP) &&
139 (rt->rt_ifp->if_drv_flags & IFF_DRV_RUNNING)) {
140 if (rt->rt_flags & RTF_GATEWAY)
141 dst = (struct sockaddr_in *)rt->rt_gateway;
142 } else {
143 IPSTAT_INC(ips_noroute);
144 IPSTAT_INC(ips_cantforward);
145 if (rt)
146 RTFREE(rt);
147 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
148 return NULL;
149 }
150 return dst;
151}
152
153/*
154 * Try to forward a packet based on the destination address.
155 * This is a fast path optimized for the plain forwarding case.
156 * If the packet is handled (and consumed) here then we return NULL;
157 * otherwise mbuf is returned and the packet should be delivered
158 * to ip_input for full processing.
159 */
160struct mbuf *
161ip_fastforward(struct mbuf *m)
162{
163 struct ip *ip;
164 struct mbuf *m0 = NULL;
165 struct route ro;
166 struct sockaddr_in *dst = NULL;
167 struct ifnet *ifp;
168 struct in_addr odest, dest;
169 uint16_t sum, ip_len, ip_off;
170 int error = 0;
171 int hlen, mtu;
172 struct m_tag *fwd_tag = NULL;
173
174 /*
175 * Are we active and forwarding packets?
176 */
177 if (!V_ipfastforward_active || !V_ipforwarding)
178 return m;
179
180 M_ASSERTVALID(m);
181 M_ASSERTPKTHDR(m);
182
183 bzero(&ro, sizeof(ro));
184
185 /*
186 * Step 1: check for packet drop conditions (and sanity checks)
187 */
188
189 /*
190 * Is entire packet big enough?
191 */
192 if (m->m_pkthdr.len < sizeof(struct ip)) {
193 IPSTAT_INC(ips_tooshort);
194 goto drop;
195 }
196
197 /*
198 * Is first mbuf large enough for ip header and is header present?
199 */
200 if (m->m_len < sizeof (struct ip) &&
201 (m = m_pullup(m, sizeof (struct ip))) == NULL) {
202 IPSTAT_INC(ips_toosmall);
203 return NULL; /* mbuf already free'd */
204 }
205
206 ip = mtod(m, struct ip *);
207
208 /*
209 * Is it IPv4?
210 */
211 if (ip->ip_v != IPVERSION) {
212 IPSTAT_INC(ips_badvers);
213 goto drop;
214 }
215
216 /*
217 * Is IP header length correct and is it in first mbuf?
218 */
219 hlen = ip->ip_hl << 2;
220 if (hlen < sizeof(struct ip)) { /* minimum header length */
221 IPSTAT_INC(ips_badhlen);
222 goto drop;
223 }
224 if (hlen > m->m_len) {
225 if ((m = m_pullup(m, hlen)) == NULL) {
226 IPSTAT_INC(ips_badhlen);
227 return NULL; /* mbuf already free'd */
228 }
229 ip = mtod(m, struct ip *);
230 }
231
232 /*
233 * Checksum correct?
234 */
235 if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED)
236 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
237 else {
238 if (hlen == sizeof(struct ip))
239 sum = in_cksum_hdr(ip);
240 else
241 sum = in_cksum(m, hlen);
242 }
243 if (sum) {
244 IPSTAT_INC(ips_badsum);
245 goto drop;
246 }
247
248 /*
249 * Remember that we have checked the IP header and found it valid.
250 */
251 m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
252
253 ip_len = ntohs(ip->ip_len);
254
255 /*
256 * Is IP length longer than packet we have got?
257 */
258 if (m->m_pkthdr.len < ip_len) {
259 IPSTAT_INC(ips_tooshort);
260 goto drop;
261 }
262
263 /*
264 * Is packet longer than IP header tells us? If yes, truncate packet.
265 */
266 if (m->m_pkthdr.len > ip_len) {
267 if (m->m_len == m->m_pkthdr.len) {
268 m->m_len = ip_len;
269 m->m_pkthdr.len = ip_len;
270 } else
271 m_adj(m, ip_len - m->m_pkthdr.len);
272 }
273
274 /*
275 * Is packet from or to 127/8?
276 */
277 if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
278 (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
279 IPSTAT_INC(ips_badaddr);
280 goto drop;
281 }
282
283#ifdef ALTQ
284 /*
285 * Is packet dropped by traffic conditioner?
286 */
287 if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
288 goto drop;
289#endif
290
291 /*
292 * Step 2: fallback conditions to normal ip_input path processing
293 */
294
295 /*
296 * Only IP packets without options
297 */
298 if (ip->ip_hl != (sizeof(struct ip) >> 2)) {
299 if (ip_doopts == 1)
300 return m;
301 else if (ip_doopts == 2) {
302 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_FILTER_PROHIB,
303 0, 0);
304 return NULL; /* mbuf already free'd */
305 }
306 /* else ignore IP options and continue */
307 }
308
309 /*
310 * Only unicast IP, not from loopback, no L2 or IP broadcast,
311 * no multicast, no INADDR_ANY
312 *
313 * XXX: Probably some of these checks could be direct drop
314 * conditions. However it is not clear whether there are some
315 * hacks or obscure behaviours which make it neccessary to
316 * let ip_input handle it. We play safe here and let ip_input
317 * deal with it until it is proven that we can directly drop it.
318 */
319 if ((m->m_flags & (M_BCAST|M_MCAST)) ||
320 (m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) ||
321 ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST ||
322 ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST ||
323 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
324 IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
325 IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) ||
326 IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr)) ||
327 ip->ip_src.s_addr == INADDR_ANY ||
328 ip->ip_dst.s_addr == INADDR_ANY )
329 return m;
330
331 /*
332 * Is it for a local address on this host?
333 */
334 if (in_localip(ip->ip_dst))
335 return m;
336
337 IPSTAT_INC(ips_total);
338
339 /*
340 * Step 3: incoming packet firewall processing
341 */
342
343 odest.s_addr = dest.s_addr = ip->ip_dst.s_addr;
344
345 /*
346 * Run through list of ipfilter hooks for input packets
347 */
348 if (!PFIL_HOOKED(&V_inet_pfil_hook))
349 goto passin;
350
351 if (pfil_run_hooks(
352 &V_inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN, NULL) ||
353 m == NULL)
354 goto drop;
355
356 M_ASSERTVALID(m);
357 M_ASSERTPKTHDR(m);
358
359 ip = mtod(m, struct ip *); /* m may have changed by pfil hook */
360 dest.s_addr = ip->ip_dst.s_addr;
361
362 /*
363 * Destination address changed?
364 */
365 if (odest.s_addr != dest.s_addr) {
366 /*
367 * Is it now for a local address on this host?
368 */
369 if (in_localip(dest))
370 goto forwardlocal;
371 /*
372 * Go on with new destination address
373 */
374 }
375
376 if (m->m_flags & M_FASTFWD_OURS) {
377 /*
378 * ipfw changed it for a local address on this host.
379 */
380 goto forwardlocal;
381 }
382
383passin:
384 /*
385 * Step 4: decrement TTL and look up route
386 */
387
388 /*
389 * Check TTL
390 */
391#ifdef IPSTEALTH
392 if (!V_ipstealth) {
393#endif
394 if (ip->ip_ttl <= IPTTLDEC) {
395 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, 0);
396 return NULL; /* mbuf already free'd */
397 }
398
399 /*
400 * Decrement the TTL and incrementally change the IP header checksum.
401 * Don't bother doing this with hw checksum offloading, it's faster
402 * doing it right here.
403 */
404 ip->ip_ttl -= IPTTLDEC;
405 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
406 ip->ip_sum -= ~htons(IPTTLDEC << 8);
407 else
408 ip->ip_sum += htons(IPTTLDEC << 8);
409#ifdef IPSTEALTH
410 }
411#endif
412
413 /*
414 * Find route to destination.
415 */
416 if ((dst = ip_findroute(&ro, dest, m)) == NULL)
417 return NULL; /* icmp unreach already sent */
418 ifp = ro.ro_rt->rt_ifp;
419
420 /*
421 * Immediately drop blackholed traffic, and directed broadcasts
422 * for either the all-ones or all-zero subnet addresses on
423 * locally attached networks.
424 */
425 if ((ro.ro_rt->rt_flags & (RTF_BLACKHOLE|RTF_BROADCAST)) != 0)
426 goto drop;
427
428 /*
429 * Step 5: outgoing firewall packet processing
430 */
431
432 /*
433 * Run through list of hooks for output packets.
434 */
435 if (!PFIL_HOOKED(&V_inet_pfil_hook))
436 goto passout;
437
438 if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_OUT, NULL) || m == NULL) {
439 goto drop;
440 }
441
442 M_ASSERTVALID(m);
443 M_ASSERTPKTHDR(m);
444
445 ip = mtod(m, struct ip *);
446 dest.s_addr = ip->ip_dst.s_addr;
447
448 /*
449 * Destination address changed?
450 */
451 if (m->m_flags & M_IP_NEXTHOP)
452 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
453 if (odest.s_addr != dest.s_addr || fwd_tag != NULL) {
454 /*
455 * Is it now for a local address on this host?
456 */
457 if (m->m_flags & M_FASTFWD_OURS || in_localip(dest)) {
458forwardlocal:
459 /*
460 * Return packet for processing by ip_input().
461 */
462 m->m_flags |= M_FASTFWD_OURS;
463 if (ro.ro_rt)
464 RTFREE(ro.ro_rt);
465 return m;
466 }
467 /*
468 * Redo route lookup with new destination address
469 */
470 if (fwd_tag) {
471 dest.s_addr = ((struct sockaddr_in *)
472 (fwd_tag + 1))->sin_addr.s_addr;
473 m_tag_delete(m, fwd_tag);
474 m->m_flags &= ~M_IP_NEXTHOP;
475 }
476 RTFREE(ro.ro_rt);
477 if ((dst = ip_findroute(&ro, dest, m)) == NULL)
478 return NULL; /* icmp unreach already sent */
479 ifp = ro.ro_rt->rt_ifp;
480 }
481
482passout:
483 /*
484 * Step 6: send off the packet
485 */
486 ip_len = ntohs(ip->ip_len);
487 ip_off = ntohs(ip->ip_off);
488
489 /*
490 * Check if route is dampned (when ARP is unable to resolve)
491 */
492 if ((ro.ro_rt->rt_flags & RTF_REJECT) &&
| 78
79#include "opt_ipfw.h"
80#include "opt_ipstealth.h"
81
82#include <sys/param.h>
83#include <sys/systm.h>
84#include <sys/kernel.h>
85#include <sys/malloc.h>
86#include <sys/mbuf.h>
87#include <sys/protosw.h>
88#include <sys/sdt.h>
89#include <sys/socket.h>
90#include <sys/sysctl.h>
91
92#include <net/pfil.h>
93#include <net/if.h>
94#include <net/if_types.h>
95#include <net/if_var.h>
96#include <net/if_dl.h>
97#include <net/route.h>
98#include <net/vnet.h>
99
100#include <netinet/in.h>
101#include <netinet/in_kdtrace.h>
102#include <netinet/in_systm.h>
103#include <netinet/in_var.h>
104#include <netinet/ip.h>
105#include <netinet/ip_var.h>
106#include <netinet/ip_icmp.h>
107#include <netinet/ip_options.h>
108
109#include <machine/in_cksum.h>
110
111static VNET_DEFINE(int, ipfastforward_active);
112#define V_ipfastforward_active VNET(ipfastforward_active)
113
114SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, fastforwarding, CTLFLAG_RW,
115 &VNET_NAME(ipfastforward_active), 0, "Enable fast IP forwarding");
116
117static struct sockaddr_in *
118ip_findroute(struct route *ro, struct in_addr dest, struct mbuf *m)
119{
120 struct sockaddr_in *dst;
121 struct rtentry *rt;
122
123 /*
124 * Find route to destination.
125 */
126 bzero(ro, sizeof(*ro));
127 dst = (struct sockaddr_in *)&ro->ro_dst;
128 dst->sin_family = AF_INET;
129 dst->sin_len = sizeof(*dst);
130 dst->sin_addr.s_addr = dest.s_addr;
131 in_rtalloc_ign(ro, 0, M_GETFIB(m));
132
133 /*
134 * Route there and interface still up?
135 */
136 rt = ro->ro_rt;
137 if (rt && (rt->rt_flags & RTF_UP) &&
138 (rt->rt_ifp->if_flags & IFF_UP) &&
139 (rt->rt_ifp->if_drv_flags & IFF_DRV_RUNNING)) {
140 if (rt->rt_flags & RTF_GATEWAY)
141 dst = (struct sockaddr_in *)rt->rt_gateway;
142 } else {
143 IPSTAT_INC(ips_noroute);
144 IPSTAT_INC(ips_cantforward);
145 if (rt)
146 RTFREE(rt);
147 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
148 return NULL;
149 }
150 return dst;
151}
152
153/*
154 * Try to forward a packet based on the destination address.
155 * This is a fast path optimized for the plain forwarding case.
156 * If the packet is handled (and consumed) here then we return NULL;
157 * otherwise mbuf is returned and the packet should be delivered
158 * to ip_input for full processing.
159 */
160struct mbuf *
161ip_fastforward(struct mbuf *m)
162{
163 struct ip *ip;
164 struct mbuf *m0 = NULL;
165 struct route ro;
166 struct sockaddr_in *dst = NULL;
167 struct ifnet *ifp;
168 struct in_addr odest, dest;
169 uint16_t sum, ip_len, ip_off;
170 int error = 0;
171 int hlen, mtu;
172 struct m_tag *fwd_tag = NULL;
173
174 /*
175 * Are we active and forwarding packets?
176 */
177 if (!V_ipfastforward_active || !V_ipforwarding)
178 return m;
179
180 M_ASSERTVALID(m);
181 M_ASSERTPKTHDR(m);
182
183 bzero(&ro, sizeof(ro));
184
185 /*
186 * Step 1: check for packet drop conditions (and sanity checks)
187 */
188
189 /*
190 * Is entire packet big enough?
191 */
192 if (m->m_pkthdr.len < sizeof(struct ip)) {
193 IPSTAT_INC(ips_tooshort);
194 goto drop;
195 }
196
197 /*
198 * Is first mbuf large enough for ip header and is header present?
199 */
200 if (m->m_len < sizeof (struct ip) &&
201 (m = m_pullup(m, sizeof (struct ip))) == NULL) {
202 IPSTAT_INC(ips_toosmall);
203 return NULL; /* mbuf already free'd */
204 }
205
206 ip = mtod(m, struct ip *);
207
208 /*
209 * Is it IPv4?
210 */
211 if (ip->ip_v != IPVERSION) {
212 IPSTAT_INC(ips_badvers);
213 goto drop;
214 }
215
216 /*
217 * Is IP header length correct and is it in first mbuf?
218 */
219 hlen = ip->ip_hl << 2;
220 if (hlen < sizeof(struct ip)) { /* minimum header length */
221 IPSTAT_INC(ips_badhlen);
222 goto drop;
223 }
224 if (hlen > m->m_len) {
225 if ((m = m_pullup(m, hlen)) == NULL) {
226 IPSTAT_INC(ips_badhlen);
227 return NULL; /* mbuf already free'd */
228 }
229 ip = mtod(m, struct ip *);
230 }
231
232 /*
233 * Checksum correct?
234 */
235 if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED)
236 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
237 else {
238 if (hlen == sizeof(struct ip))
239 sum = in_cksum_hdr(ip);
240 else
241 sum = in_cksum(m, hlen);
242 }
243 if (sum) {
244 IPSTAT_INC(ips_badsum);
245 goto drop;
246 }
247
248 /*
249 * Remember that we have checked the IP header and found it valid.
250 */
251 m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
252
253 ip_len = ntohs(ip->ip_len);
254
255 /*
256 * Is IP length longer than packet we have got?
257 */
258 if (m->m_pkthdr.len < ip_len) {
259 IPSTAT_INC(ips_tooshort);
260 goto drop;
261 }
262
263 /*
264 * Is packet longer than IP header tells us? If yes, truncate packet.
265 */
266 if (m->m_pkthdr.len > ip_len) {
267 if (m->m_len == m->m_pkthdr.len) {
268 m->m_len = ip_len;
269 m->m_pkthdr.len = ip_len;
270 } else
271 m_adj(m, ip_len - m->m_pkthdr.len);
272 }
273
274 /*
275 * Is packet from or to 127/8?
276 */
277 if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
278 (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
279 IPSTAT_INC(ips_badaddr);
280 goto drop;
281 }
282
283#ifdef ALTQ
284 /*
285 * Is packet dropped by traffic conditioner?
286 */
287 if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
288 goto drop;
289#endif
290
291 /*
292 * Step 2: fallback conditions to normal ip_input path processing
293 */
294
295 /*
296 * Only IP packets without options
297 */
298 if (ip->ip_hl != (sizeof(struct ip) >> 2)) {
299 if (ip_doopts == 1)
300 return m;
301 else if (ip_doopts == 2) {
302 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_FILTER_PROHIB,
303 0, 0);
304 return NULL; /* mbuf already free'd */
305 }
306 /* else ignore IP options and continue */
307 }
308
309 /*
310 * Only unicast IP, not from loopback, no L2 or IP broadcast,
311 * no multicast, no INADDR_ANY
312 *
313 * XXX: Probably some of these checks could be direct drop
314 * conditions. However it is not clear whether there are some
315 * hacks or obscure behaviours which make it neccessary to
316 * let ip_input handle it. We play safe here and let ip_input
317 * deal with it until it is proven that we can directly drop it.
318 */
319 if ((m->m_flags & (M_BCAST|M_MCAST)) ||
320 (m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) ||
321 ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST ||
322 ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST ||
323 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
324 IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
325 IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) ||
326 IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr)) ||
327 ip->ip_src.s_addr == INADDR_ANY ||
328 ip->ip_dst.s_addr == INADDR_ANY )
329 return m;
330
331 /*
332 * Is it for a local address on this host?
333 */
334 if (in_localip(ip->ip_dst))
335 return m;
336
337 IPSTAT_INC(ips_total);
338
339 /*
340 * Step 3: incoming packet firewall processing
341 */
342
343 odest.s_addr = dest.s_addr = ip->ip_dst.s_addr;
344
345 /*
346 * Run through list of ipfilter hooks for input packets
347 */
348 if (!PFIL_HOOKED(&V_inet_pfil_hook))
349 goto passin;
350
351 if (pfil_run_hooks(
352 &V_inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN, NULL) ||
353 m == NULL)
354 goto drop;
355
356 M_ASSERTVALID(m);
357 M_ASSERTPKTHDR(m);
358
359 ip = mtod(m, struct ip *); /* m may have changed by pfil hook */
360 dest.s_addr = ip->ip_dst.s_addr;
361
362 /*
363 * Destination address changed?
364 */
365 if (odest.s_addr != dest.s_addr) {
366 /*
367 * Is it now for a local address on this host?
368 */
369 if (in_localip(dest))
370 goto forwardlocal;
371 /*
372 * Go on with new destination address
373 */
374 }
375
376 if (m->m_flags & M_FASTFWD_OURS) {
377 /*
378 * ipfw changed it for a local address on this host.
379 */
380 goto forwardlocal;
381 }
382
383passin:
384 /*
385 * Step 4: decrement TTL and look up route
386 */
387
388 /*
389 * Check TTL
390 */
391#ifdef IPSTEALTH
392 if (!V_ipstealth) {
393#endif
394 if (ip->ip_ttl <= IPTTLDEC) {
395 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, 0);
396 return NULL; /* mbuf already free'd */
397 }
398
399 /*
400 * Decrement the TTL and incrementally change the IP header checksum.
401 * Don't bother doing this with hw checksum offloading, it's faster
402 * doing it right here.
403 */
404 ip->ip_ttl -= IPTTLDEC;
405 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
406 ip->ip_sum -= ~htons(IPTTLDEC << 8);
407 else
408 ip->ip_sum += htons(IPTTLDEC << 8);
409#ifdef IPSTEALTH
410 }
411#endif
412
413 /*
414 * Find route to destination.
415 */
416 if ((dst = ip_findroute(&ro, dest, m)) == NULL)
417 return NULL; /* icmp unreach already sent */
418 ifp = ro.ro_rt->rt_ifp;
419
420 /*
421 * Immediately drop blackholed traffic, and directed broadcasts
422 * for either the all-ones or all-zero subnet addresses on
423 * locally attached networks.
424 */
425 if ((ro.ro_rt->rt_flags & (RTF_BLACKHOLE|RTF_BROADCAST)) != 0)
426 goto drop;
427
428 /*
429 * Step 5: outgoing firewall packet processing
430 */
431
432 /*
433 * Run through list of hooks for output packets.
434 */
435 if (!PFIL_HOOKED(&V_inet_pfil_hook))
436 goto passout;
437
438 if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_OUT, NULL) || m == NULL) {
439 goto drop;
440 }
441
442 M_ASSERTVALID(m);
443 M_ASSERTPKTHDR(m);
444
445 ip = mtod(m, struct ip *);
446 dest.s_addr = ip->ip_dst.s_addr;
447
448 /*
449 * Destination address changed?
450 */
451 if (m->m_flags & M_IP_NEXTHOP)
452 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
453 if (odest.s_addr != dest.s_addr || fwd_tag != NULL) {
454 /*
455 * Is it now for a local address on this host?
456 */
457 if (m->m_flags & M_FASTFWD_OURS || in_localip(dest)) {
458forwardlocal:
459 /*
460 * Return packet for processing by ip_input().
461 */
462 m->m_flags |= M_FASTFWD_OURS;
463 if (ro.ro_rt)
464 RTFREE(ro.ro_rt);
465 return m;
466 }
467 /*
468 * Redo route lookup with new destination address
469 */
470 if (fwd_tag) {
471 dest.s_addr = ((struct sockaddr_in *)
472 (fwd_tag + 1))->sin_addr.s_addr;
473 m_tag_delete(m, fwd_tag);
474 m->m_flags &= ~M_IP_NEXTHOP;
475 }
476 RTFREE(ro.ro_rt);
477 if ((dst = ip_findroute(&ro, dest, m)) == NULL)
478 return NULL; /* icmp unreach already sent */
479 ifp = ro.ro_rt->rt_ifp;
480 }
481
482passout:
483 /*
484 * Step 6: send off the packet
485 */
486 ip_len = ntohs(ip->ip_len);
487 ip_off = ntohs(ip->ip_off);
488
489 /*
490 * Check if route is dampned (when ARP is unable to resolve)
491 */
492 if ((ro.ro_rt->rt_flags & RTF_REJECT) &&
|
493 (ro.ro_rt->rt_rmx.rmx_expire == 0 ||
494 time_uptime < ro.ro_rt->rt_rmx.rmx_expire)) {
| 493 (ro.ro_rt->rt_expire == 0 || time_uptime < ro.ro_rt->rt_expire)) {
|
495 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
496 goto consumed;
497 }
498
499#ifndef ALTQ
500 /*
501 * Check if there is enough space in the interface queue
502 */
503 if ((ifp->if_snd.ifq_len + ip_len / ifp->if_mtu + 1) >=
504 ifp->if_snd.ifq_maxlen) {
505 IPSTAT_INC(ips_odropped);
506 /* would send source quench here but that is depreciated */
507 goto drop;
508 }
509#endif
510
511 /*
512 * Check if media link state of interface is not down
513 */
514 if (ifp->if_link_state == LINK_STATE_DOWN) {
515 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
516 goto consumed;
517 }
518
519 /*
520 * Check if packet fits MTU or if hardware will fragment for us
521 */
| 494 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
495 goto consumed;
496 }
497
498#ifndef ALTQ
499 /*
500 * Check if there is enough space in the interface queue
501 */
502 if ((ifp->if_snd.ifq_len + ip_len / ifp->if_mtu + 1) >=
503 ifp->if_snd.ifq_maxlen) {
504 IPSTAT_INC(ips_odropped);
505 /* would send source quench here but that is depreciated */
506 goto drop;
507 }
508#endif
509
510 /*
511 * Check if media link state of interface is not down
512 */
513 if (ifp->if_link_state == LINK_STATE_DOWN) {
514 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
515 goto consumed;
516 }
517
518 /*
519 * Check if packet fits MTU or if hardware will fragment for us
520 */
|
522 if (ro.ro_rt->rt_rmx.rmx_mtu)
523 mtu = min(ro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu);
| 521 if (ro.ro_rt->rt_mtu)
522 mtu = min(ro.ro_rt->rt_mtu, ifp->if_mtu);
|
524 else
525 mtu = ifp->if_mtu;
526
527 if (ip_len <= mtu ||
528 (ifp->if_hwassist & CSUM_FRAGMENT && (ip_off & IP_DF) == 0)) {
529 /*
530 * Avoid confusing lower layers.
531 */
532 m_clrprotoflags(m);
533 /*
534 * Send off the packet via outgoing interface
535 */
536 IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
537 error = (*ifp->if_output)(ifp, m,
538 (struct sockaddr *)dst, &ro);
539 } else {
540 /*
541 * Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery
542 */
543 if (ip_off & IP_DF) {
544 IPSTAT_INC(ips_cantfrag);
545 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG,
546 0, mtu);
547 goto consumed;
548 } else {
549 /*
550 * We have to fragment the packet
551 */
552 m->m_pkthdr.csum_flags |= CSUM_IP;
553 if (ip_fragment(ip, &m, mtu, ifp->if_hwassist))
554 goto drop;
555 KASSERT(m != NULL, ("null mbuf and no error"));
556 /*
557 * Send off the fragments via outgoing interface
558 */
559 error = 0;
560 do {
561 m0 = m->m_nextpkt;
562 m->m_nextpkt = NULL;
563 /*
564 * Avoid confusing lower layers.
565 */
566 m_clrprotoflags(m);
567
568 IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
569 error = (*ifp->if_output)(ifp, m,
570 (struct sockaddr *)dst, &ro);
571 if (error)
572 break;
573 } while ((m = m0) != NULL);
574 if (error) {
575 /* Reclaim remaining fragments */
576 for (m = m0; m; m = m0) {
577 m0 = m->m_nextpkt;
578 m_freem(m);
579 }
580 } else
581 IPSTAT_INC(ips_fragmented);
582 }
583 }
584
585 if (error != 0)
586 IPSTAT_INC(ips_odropped);
587 else {
| 523 else
524 mtu = ifp->if_mtu;
525
526 if (ip_len <= mtu ||
527 (ifp->if_hwassist & CSUM_FRAGMENT && (ip_off & IP_DF) == 0)) {
528 /*
529 * Avoid confusing lower layers.
530 */
531 m_clrprotoflags(m);
532 /*
533 * Send off the packet via outgoing interface
534 */
535 IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
536 error = (*ifp->if_output)(ifp, m,
537 (struct sockaddr *)dst, &ro);
538 } else {
539 /*
540 * Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery
541 */
542 if (ip_off & IP_DF) {
543 IPSTAT_INC(ips_cantfrag);
544 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG,
545 0, mtu);
546 goto consumed;
547 } else {
548 /*
549 * We have to fragment the packet
550 */
551 m->m_pkthdr.csum_flags |= CSUM_IP;
552 if (ip_fragment(ip, &m, mtu, ifp->if_hwassist))
553 goto drop;
554 KASSERT(m != NULL, ("null mbuf and no error"));
555 /*
556 * Send off the fragments via outgoing interface
557 */
558 error = 0;
559 do {
560 m0 = m->m_nextpkt;
561 m->m_nextpkt = NULL;
562 /*
563 * Avoid confusing lower layers.
564 */
565 m_clrprotoflags(m);
566
567 IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
568 error = (*ifp->if_output)(ifp, m,
569 (struct sockaddr *)dst, &ro);
570 if (error)
571 break;
572 } while ((m = m0) != NULL);
573 if (error) {
574 /* Reclaim remaining fragments */
575 for (m = m0; m; m = m0) {
576 m0 = m->m_nextpkt;
577 m_freem(m);
578 }
579 } else
580 IPSTAT_INC(ips_fragmented);
581 }
582 }
583
584 if (error != 0)
585 IPSTAT_INC(ips_odropped);
586 else {
|
588 ro.ro_rt->rt_rmx.rmx_pksent++;
| 587 counter_u64_add(ro.ro_rt->rt_pksent, 1);
|
589 IPSTAT_INC(ips_forward);
590 IPSTAT_INC(ips_fastforward);
591 }
592consumed:
593 RTFREE(ro.ro_rt);
594 return NULL;
595drop:
596 if (m)
597 m_freem(m);
598 if (ro.ro_rt)
599 RTFREE(ro.ro_rt);
600 return NULL;
601}
| 588 IPSTAT_INC(ips_forward);
589 IPSTAT_INC(ips_fastforward);
590 }
591consumed:
592 RTFREE(ro.ro_rt);
593 return NULL;
594drop:
595 if (m)
596 m_freem(m);
597 if (ro.ro_rt)
598 RTFREE(ro.ro_rt);
599 return NULL;
600}
|