2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
6 * The options processing module for ip.c
8 * Authors: A.N.Kuznetsov
12 #include <linux/capability.h>
13 #include <linux/module.h>
14 #include <linux/types.h>
15 #include <asm/uaccess.h>
16 #include <linux/skbuff.h>
18 #include <linux/icmp.h>
19 #include <linux/netdevice.h>
20 #include <linux/rtnetlink.h>
24 #include <net/route.h>
25 #include <net/cipso_ipv4.h>
28 * Write options to IP header, record destination address to
29 * source route option, address of outgoing interface
30 * (we should already know it, so that this function is allowed be
31 * called only after routing decision) and timestamp,
32 * if we originate this datagram.
34 * daddr is real destination address, next hop is recorded in IP header.
35 * saddr is address of outgoing interface.
38 void ip_options_build(struct sk_buff * skb, struct ip_options * opt,
39 __be32 daddr, struct rtable *rt, int is_frag)
41 unsigned char *iph = skb_network_header(skb);
43 memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
44 memcpy(iph+sizeof(struct iphdr), opt->__data, opt->optlen);
45 opt = &(IPCB(skb)->opt);
48 memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);
52 ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, rt);
54 ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, rt);
55 if (opt->ts_needtime) {
59 midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC);
60 memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
65 memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
70 memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
72 opt->ts_needaddr = opt->ts_needtime = 0;
77 * Provided (sopt, skb) points to received options,
78 * build in dopt compiled option set appropriate for answering.
79 * i.e. invert SRR option, copy anothers,
80 * and grab room in RR/TS options.
82 * NOTE: dopt cannot point to skb.
85 int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb)
87 struct ip_options *sopt;
88 unsigned char *sptr, *dptr;
93 memset(dopt, 0, sizeof(struct ip_options));
95 sopt = &(IPCB(skb)->opt);
97 if (sopt->optlen == 0) {
102 sptr = skb_network_header(skb);
105 daddr = skb->rtable->rt_spec_dst;
108 optlen = sptr[sopt->rr+1];
109 soffset = sptr[sopt->rr+2];
110 dopt->rr = dopt->optlen + sizeof(struct iphdr);
111 memcpy(dptr, sptr+sopt->rr, optlen);
112 if (sopt->rr_needaddr && soffset <= optlen) {
113 if (soffset + 3 > optlen)
115 dptr[2] = soffset + 4;
116 dopt->rr_needaddr = 1;
119 dopt->optlen += optlen;
122 optlen = sptr[sopt->ts+1];
123 soffset = sptr[sopt->ts+2];
124 dopt->ts = dopt->optlen + sizeof(struct iphdr);
125 memcpy(dptr, sptr+sopt->ts, optlen);
126 if (soffset <= optlen) {
127 if (sopt->ts_needaddr) {
128 if (soffset + 3 > optlen)
130 dopt->ts_needaddr = 1;
133 if (sopt->ts_needtime) {
134 if (soffset + 3 > optlen)
136 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
137 dopt->ts_needtime = 1;
140 dopt->ts_needtime = 0;
142 if (soffset + 8 <= optlen) {
145 memcpy(&addr, sptr+soffset-1, 4);
146 if (inet_addr_type(dev_net(skb->dst->dev), addr) != RTN_LOCAL) {
147 dopt->ts_needtime = 1;
156 dopt->optlen += optlen;
159 unsigned char * start = sptr+sopt->srr;
165 if (soffset > optlen)
166 soffset = optlen + 1;
169 memcpy(&faddr, &start[soffset-1], 4);
170 for (soffset-=4, doffset=4; soffset > 3; soffset-=4, doffset+=4)
171 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
173 * RFC1812 requires to fix illegal source routes.
175 if (memcmp(&ip_hdr(skb)->saddr,
176 &start[soffset + 3], 4) == 0)
180 memcpy(&start[doffset-1], &daddr, 4);
186 dopt->srr = dopt->optlen + sizeof(struct iphdr);
187 dopt->optlen += doffset+3;
188 dopt->is_strictroute = sopt->is_strictroute;
192 optlen = sptr[sopt->cipso+1];
193 dopt->cipso = dopt->optlen+sizeof(struct iphdr);
194 memcpy(dptr, sptr+sopt->cipso, optlen);
196 dopt->optlen += optlen;
198 while (dopt->optlen & 3) {
206 * Options "fragmenting", just fill options not
207 * allowed in fragments with NOOPs.
208 * Simple and stupid 8), but the most efficient way.
211 void ip_options_fragment(struct sk_buff * skb)
213 unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
214 struct ip_options * opt = &(IPCB(skb)->opt);
228 if (optlen<2 || optlen>l)
230 if (!IPOPT_COPIED(*optptr))
231 memset(optptr, IPOPT_NOOP, optlen);
237 opt->rr_needaddr = 0;
238 opt->ts_needaddr = 0;
239 opt->ts_needtime = 0;
244 * Verify options and fill pointers in struct options.
245 * Caller should clear *opt, and set opt->data.
246 * If opt == NULL, then skb->data should point to IP header.
249 int ip_options_compile(struct net *net,
250 struct ip_options * opt, struct sk_buff * skb)
254 unsigned char * optptr;
256 unsigned char * pp_ptr = NULL;
257 struct rtable *rt = NULL;
261 optptr = (unsigned char *)&(ip_hdr(skb)[1]);
263 optptr = opt->__data;
264 iph = optptr - sizeof(struct iphdr);
266 for (l = opt->optlen; l > 0; ) {
269 for (optptr++, l--; l>0; optptr++, l--) {
270 if (*optptr != IPOPT_END) {
282 if (optlen<2 || optlen>l) {
297 /* NB: cf RFC-1812 5.2.4.1 */
303 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
307 memcpy(&opt->faddr, &optptr[3], 4);
309 memmove(&optptr[3], &optptr[7], optlen-7);
311 opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
312 opt->srr = optptr - iph;
327 if (optptr[2] <= optlen) {
328 if (optptr[2]+3 > optlen) {
333 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
337 opt->rr_needaddr = 1;
339 opt->rr = optptr - iph;
341 case IPOPT_TIMESTAMP:
354 if (optptr[2] <= optlen) {
355 __be32 *timeptr = NULL;
356 if (optptr[2]+3 > optptr[1]) {
360 switch (optptr[3]&0xF) {
361 case IPOPT_TS_TSONLY:
362 opt->ts = optptr - iph;
364 timeptr = (__be32*)&optptr[optptr[2]-1];
365 opt->ts_needtime = 1;
368 case IPOPT_TS_TSANDADDR:
369 if (optptr[2]+7 > optptr[1]) {
373 opt->ts = optptr - iph;
375 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
376 timeptr = (__be32*)&optptr[optptr[2]+3];
378 opt->ts_needaddr = 1;
379 opt->ts_needtime = 1;
382 case IPOPT_TS_PRESPEC:
383 if (optptr[2]+7 > optptr[1]) {
387 opt->ts = optptr - iph;
390 memcpy(&addr, &optptr[optptr[2]-1], 4);
391 if (inet_addr_type(net, addr) == RTN_UNICAST)
394 timeptr = (__be32*)&optptr[optptr[2]+3];
396 opt->ts_needtime = 1;
400 if (!skb && !capable(CAP_NET_RAW)) {
410 midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC);
411 memcpy(timeptr, &midtime, sizeof(__be32));
415 unsigned overflow = optptr[3]>>4;
416 if (overflow == 15) {
420 opt->ts = optptr - iph;
422 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
432 if (optptr[2] == 0 && optptr[3] == 0)
433 opt->router_alert = optptr - iph;
436 if ((!skb && !capable(CAP_NET_RAW)) || opt->cipso) {
440 opt->cipso = optptr - iph;
441 if (cipso_v4_validate(skb, &optptr)) {
449 if (!skb && !capable(CAP_NET_RAW)) {
465 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
472 * Undo all the changes done by ip_options_compile().
475 void ip_options_undo(struct ip_options * opt)
478 unsigned char * optptr = opt->__data+opt->srr-sizeof(struct iphdr);
479 memmove(optptr+7, optptr+3, optptr[1]-7);
480 memcpy(optptr+3, &opt->faddr, 4);
482 if (opt->rr_needaddr) {
483 unsigned char * optptr = opt->__data+opt->rr-sizeof(struct iphdr);
485 memset(&optptr[optptr[2]-1], 0, 4);
488 unsigned char * optptr = opt->__data+opt->ts-sizeof(struct iphdr);
489 if (opt->ts_needtime) {
491 memset(&optptr[optptr[2]-1], 0, 4);
492 if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
495 if (opt->ts_needaddr) {
497 memset(&optptr[optptr[2]-1], 0, 4);
502 static struct ip_options *ip_options_get_alloc(const int optlen)
504 return kzalloc(sizeof(struct ip_options) + ((optlen + 3) & ~3),
508 static int ip_options_get_finish(struct net *net, struct ip_options **optp,
509 struct ip_options *opt, int optlen)
512 opt->__data[optlen++] = IPOPT_END;
513 opt->optlen = optlen;
514 if (optlen && ip_options_compile(net, opt, NULL)) {
523 int ip_options_get_from_user(struct net *net, struct ip_options **optp,
524 unsigned char __user *data, int optlen)
526 struct ip_options *opt = ip_options_get_alloc(optlen);
530 if (optlen && copy_from_user(opt->__data, data, optlen)) {
534 return ip_options_get_finish(net, optp, opt, optlen);
537 int ip_options_get(struct net *net, struct ip_options **optp,
538 unsigned char *data, int optlen)
540 struct ip_options *opt = ip_options_get_alloc(optlen);
545 memcpy(opt->__data, data, optlen);
546 return ip_options_get_finish(net, optp, opt, optlen);
549 void ip_forward_options(struct sk_buff *skb)
551 struct ip_options * opt = &(IPCB(skb)->opt);
552 unsigned char * optptr;
553 struct rtable *rt = skb->rtable;
554 unsigned char *raw = skb_network_header(skb);
556 if (opt->rr_needaddr) {
557 optptr = (unsigned char *)raw + opt->rr;
558 ip_rt_get_source(&optptr[optptr[2]-5], rt);
561 if (opt->srr_is_hit) {
562 int srrptr, srrspace;
564 optptr = raw + opt->srr;
566 for ( srrptr=optptr[2], srrspace = optptr[1];
570 if (srrptr + 3 > srrspace)
572 if (memcmp(&rt->rt_dst, &optptr[srrptr-1], 4) == 0)
575 if (srrptr + 3 <= srrspace) {
577 ip_rt_get_source(&optptr[srrptr-1], rt);
578 ip_hdr(skb)->daddr = rt->rt_dst;
579 optptr[2] = srrptr+4;
580 } else if (net_ratelimit())
581 printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n");
582 if (opt->ts_needaddr) {
583 optptr = raw + opt->ts;
584 ip_rt_get_source(&optptr[optptr[2]-9], rt);
588 if (opt->is_changed) {
590 ip_send_check(ip_hdr(skb));
594 int ip_options_rcv_srr(struct sk_buff *skb)
596 struct ip_options *opt = &(IPCB(skb)->opt);
597 int srrspace, srrptr;
599 struct iphdr *iph = ip_hdr(skb);
600 unsigned char *optptr = skb_network_header(skb) + opt->srr;
601 struct rtable *rt = skb->rtable;
608 if (skb->pkt_type != PACKET_HOST)
610 if (rt->rt_type == RTN_UNICAST) {
611 if (!opt->is_strictroute)
613 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
616 if (rt->rt_type != RTN_LOCAL)
619 for (srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
620 if (srrptr + 3 > srrspace) {
621 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
624 memcpy(&nexthop, &optptr[srrptr-1], 4);
628 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
630 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
636 if (rt2->rt_type != RTN_LOCAL)
638 /* Superfast 8) loopback forward */
639 memcpy(&iph->daddr, &optptr[srrptr-1], 4);
642 if (srrptr <= srrspace) {