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 * Version: $Id: ip_options.c,v 1.21 2001/09/01 00:31:50 davem Exp $
10 * Authors: A.N.Kuznetsov
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>
26 * Write options to IP header, record destination address to
27 * source route option, address of outgoing interface
28 * (we should already know it, so that this function is allowed be
29 * called only after routing decision) and timestamp,
30 * if we originate this datagram.
32 * daddr is real destination address, next hop is recorded in IP header.
33 * saddr is address of outgoing interface.
36 void ip_options_build(struct sk_buff * skb, struct ip_options * opt,
37 u32 daddr, struct rtable *rt, int is_frag)
39 unsigned char * iph = skb->nh.raw;
41 memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
42 memcpy(iph+sizeof(struct iphdr), opt->__data, opt->optlen);
43 opt = &(IPCB(skb)->opt);
47 memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);
51 ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, rt);
53 ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, rt);
54 if (opt->ts_needtime) {
58 midtime = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000);
59 memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
64 memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
69 memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
71 opt->ts_needaddr = opt->ts_needtime = 0;
76 * Provided (sopt, skb) points to received options,
77 * build in dopt compiled option set appropriate for answering.
78 * i.e. invert SRR option, copy anothers,
79 * and grab room in RR/TS options.
81 * NOTE: dopt cannot point to skb.
84 int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb)
86 struct ip_options *sopt;
87 unsigned char *sptr, *dptr;
92 memset(dopt, 0, sizeof(struct ip_options));
96 sopt = &(IPCB(skb)->opt);
98 if (sopt->optlen == 0) {
107 daddr = ((struct rtable*)skb->dst)->rt_spec_dst;
109 daddr = skb->nh.iph->daddr;
112 optlen = sptr[sopt->rr+1];
113 soffset = sptr[sopt->rr+2];
114 dopt->rr = dopt->optlen + sizeof(struct iphdr);
115 memcpy(dptr, sptr+sopt->rr, optlen);
116 if (sopt->rr_needaddr && soffset <= optlen) {
117 if (soffset + 3 > optlen)
119 dptr[2] = soffset + 4;
120 dopt->rr_needaddr = 1;
123 dopt->optlen += optlen;
126 optlen = sptr[sopt->ts+1];
127 soffset = sptr[sopt->ts+2];
128 dopt->ts = dopt->optlen + sizeof(struct iphdr);
129 memcpy(dptr, sptr+sopt->ts, optlen);
130 if (soffset <= optlen) {
131 if (sopt->ts_needaddr) {
132 if (soffset + 3 > optlen)
134 dopt->ts_needaddr = 1;
137 if (sopt->ts_needtime) {
138 if (soffset + 3 > optlen)
140 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
141 dopt->ts_needtime = 1;
144 dopt->ts_needtime = 0;
146 if (soffset + 8 <= optlen) {
149 memcpy(&addr, sptr+soffset-1, 4);
150 if (inet_addr_type(addr) != RTN_LOCAL) {
151 dopt->ts_needtime = 1;
160 dopt->optlen += optlen;
163 unsigned char * start = sptr+sopt->srr;
169 if (soffset > optlen)
170 soffset = optlen + 1;
173 memcpy(&faddr, &start[soffset-1], 4);
174 for (soffset-=4, doffset=4; soffset > 3; soffset-=4, doffset+=4)
175 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
177 * RFC1812 requires to fix illegal source routes.
179 if (memcmp(&skb->nh.iph->saddr, &start[soffset+3], 4) == 0)
183 memcpy(&start[doffset-1], &daddr, 4);
189 dopt->srr = dopt->optlen + sizeof(struct iphdr);
190 dopt->optlen += doffset+3;
191 dopt->is_strictroute = sopt->is_strictroute;
194 while (dopt->optlen & 3) {
202 * Options "fragmenting", just fill options not
203 * allowed in fragments with NOOPs.
204 * Simple and stupid 8), but the most efficient way.
207 void ip_options_fragment(struct sk_buff * skb)
209 unsigned char * optptr = skb->nh.raw;
210 struct ip_options * opt = &(IPCB(skb)->opt);
224 if (optlen<2 || optlen>l)
226 if (!IPOPT_COPIED(*optptr))
227 memset(optptr, IPOPT_NOOP, optlen);
233 opt->rr_needaddr = 0;
234 opt->ts_needaddr = 0;
235 opt->ts_needtime = 0;
240 * Verify options and fill pointers in struct options.
241 * Caller should clear *opt, and set opt->data.
242 * If opt == NULL, then skb->data should point to IP header.
245 int ip_options_compile(struct ip_options * opt, struct sk_buff * skb)
249 unsigned char * optptr;
251 unsigned char * pp_ptr = NULL;
252 struct rtable *rt = skb ? (struct rtable*)skb->dst : NULL;
255 opt = &(IPCB(skb)->opt);
256 memset(opt, 0, sizeof(struct ip_options));
258 opt->optlen = ((struct iphdr *)iph)->ihl*4 - sizeof(struct iphdr);
259 optptr = iph + sizeof(struct iphdr);
262 optptr = opt->is_data ? opt->__data : (unsigned char*)&(skb->nh.iph[1]);
263 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 __u32 * 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 = (__u32*)&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 = (__u32*)&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(addr) == RTN_UNICAST)
394 timeptr = (__u32*)&optptr[optptr[2]+3];
396 opt->ts_needtime = 1;
400 if (!skb && !capable(CAP_NET_RAW)) {
409 do_gettimeofday(&tv);
410 midtime = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000);
411 memcpy(timeptr, &midtime, sizeof(__u32));
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;
438 if (!skb && !capable(CAP_NET_RAW)) {
454 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
461 * Undo all the changes done by ip_options_compile().
464 void ip_options_undo(struct ip_options * opt)
467 unsigned char * optptr = opt->__data+opt->srr-sizeof(struct iphdr);
468 memmove(optptr+7, optptr+3, optptr[1]-7);
469 memcpy(optptr+3, &opt->faddr, 4);
471 if (opt->rr_needaddr) {
472 unsigned char * optptr = opt->__data+opt->rr-sizeof(struct iphdr);
474 memset(&optptr[optptr[2]-1], 0, 4);
477 unsigned char * optptr = opt->__data+opt->ts-sizeof(struct iphdr);
478 if (opt->ts_needtime) {
480 memset(&optptr[optptr[2]-1], 0, 4);
481 if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
484 if (opt->ts_needaddr) {
486 memset(&optptr[optptr[2]-1], 0, 4);
491 int ip_options_get(struct ip_options **optp, unsigned char *data, int optlen, int user)
493 struct ip_options *opt;
495 opt = kmalloc(sizeof(struct ip_options)+((optlen+3)&~3), GFP_KERNEL);
498 memset(opt, 0, sizeof(struct ip_options));
501 if (copy_from_user(opt->__data, data, optlen)) {
506 memcpy(opt->__data, data, optlen);
509 opt->__data[optlen++] = IPOPT_END;
510 opt->optlen = optlen;
512 opt->is_setbyuser = 1;
513 if (optlen && ip_options_compile(opt, NULL)) {
523 void ip_forward_options(struct sk_buff *skb)
525 struct ip_options * opt = &(IPCB(skb)->opt);
526 unsigned char * optptr;
527 struct rtable *rt = (struct rtable*)skb->dst;
528 unsigned char *raw = skb->nh.raw;
530 if (opt->rr_needaddr) {
531 optptr = (unsigned char *)raw + opt->rr;
532 ip_rt_get_source(&optptr[optptr[2]-5], rt);
535 if (opt->srr_is_hit) {
536 int srrptr, srrspace;
538 optptr = raw + opt->srr;
540 for ( srrptr=optptr[2], srrspace = optptr[1];
544 if (srrptr + 3 > srrspace)
546 if (memcmp(&rt->rt_dst, &optptr[srrptr-1], 4) == 0)
549 if (srrptr + 3 <= srrspace) {
551 ip_rt_get_source(&optptr[srrptr-1], rt);
552 skb->nh.iph->daddr = rt->rt_dst;
553 optptr[2] = srrptr+4;
554 } else if (net_ratelimit())
555 printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n");
556 if (opt->ts_needaddr) {
557 optptr = raw + opt->ts;
558 ip_rt_get_source(&optptr[optptr[2]-9], rt);
562 if (opt->is_changed) {
564 ip_send_check(skb->nh.iph);
568 int ip_options_rcv_srr(struct sk_buff *skb)
570 struct ip_options *opt = &(IPCB(skb)->opt);
571 int srrspace, srrptr;
573 struct iphdr *iph = skb->nh.iph;
574 unsigned char * optptr = skb->nh.raw + opt->srr;
575 struct rtable *rt = (struct rtable*)skb->dst;
582 if (skb->pkt_type != PACKET_HOST)
584 if (rt->rt_type == RTN_UNICAST) {
585 if (!opt->is_strictroute)
587 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
590 if (rt->rt_type != RTN_LOCAL)
593 for (srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
594 if (srrptr + 3 > srrspace) {
595 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
598 memcpy(&nexthop, &optptr[srrptr-1], 4);
600 rt = (struct rtable*)skb->dst;
602 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
603 rt2 = (struct rtable*)skb->dst;
604 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
606 skb->dst = &rt->u.dst;
610 if (rt2->rt_type != RTN_LOCAL)
612 /* Superfast 8) loopback forward */
613 memcpy(&iph->daddr, &optptr[srrptr-1], 4);
616 if (srrptr <= srrspace) {