1 // SPDX-License-Identifier: GPL-2.0
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
7 * The options processing module for ip.c
9 * Authors: A.N.Kuznetsov
13 #define pr_fmt(fmt) "IPv4: " fmt
15 #include <linux/capability.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/types.h>
19 #include <linux/uaccess.h>
20 #include <asm/unaligned.h>
21 #include <linux/skbuff.h>
23 #include <linux/icmp.h>
24 #include <linux/netdevice.h>
25 #include <linux/rtnetlink.h>
29 #include <net/route.h>
30 #include <net/cipso_ipv4.h>
31 #include <net/ip_fib.h>
34 * Write options to IP header, record destination address to
35 * source route option, address of outgoing interface
36 * (we should already know it, so that this function is allowed be
37 * called only after routing decision) and timestamp,
38 * if we originate this datagram.
40 * daddr is real destination address, next hop is recorded in IP header.
41 * saddr is address of outgoing interface.
44 void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
45 __be32 daddr, struct rtable *rt, int is_frag)
47 unsigned char *iph = skb_network_header(skb);
49 memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
50 memcpy(iph + sizeof(struct iphdr), opt->__data, opt->optlen);
51 opt = &(IPCB(skb)->opt);
54 memcpy(iph + opt->srr + iph[opt->srr + 1] - 4, &daddr, 4);
58 ip_rt_get_source(iph + opt->rr + iph[opt->rr + 2] - 5, skb, rt);
60 ip_rt_get_source(iph + opt->ts + iph[opt->ts + 2] - 9, skb, rt);
61 if (opt->ts_needtime) {
64 midtime = inet_current_timestamp();
65 memcpy(iph + opt->ts + iph[opt->ts + 2] - 5, &midtime, 4);
70 memset(iph + opt->rr, IPOPT_NOP, iph[opt->rr + 1]);
75 memset(iph + opt->ts, IPOPT_NOP, iph[opt->ts + 1]);
77 opt->ts_needaddr = opt->ts_needtime = 0;
82 * Provided (sopt, skb) points to received options,
83 * build in dopt compiled option set appropriate for answering.
84 * i.e. invert SRR option, copy anothers,
85 * and grab room in RR/TS options.
87 * NOTE: dopt cannot point to skb.
90 int __ip_options_echo(struct net *net, struct ip_options *dopt,
91 struct sk_buff *skb, const struct ip_options *sopt)
93 unsigned char *sptr, *dptr;
97 memset(dopt, 0, sizeof(struct ip_options));
99 if (sopt->optlen == 0)
102 sptr = skb_network_header(skb);
106 optlen = sptr[sopt->rr+1];
107 soffset = sptr[sopt->rr+2];
108 dopt->rr = dopt->optlen + sizeof(struct iphdr);
109 memcpy(dptr, sptr+sopt->rr, optlen);
110 if (sopt->rr_needaddr && soffset <= optlen) {
111 if (soffset + 3 > optlen)
113 dptr[2] = soffset + 4;
114 dopt->rr_needaddr = 1;
117 dopt->optlen += optlen;
120 optlen = sptr[sopt->ts+1];
121 soffset = sptr[sopt->ts+2];
122 dopt->ts = dopt->optlen + sizeof(struct iphdr);
123 memcpy(dptr, sptr+sopt->ts, optlen);
124 if (soffset <= optlen) {
125 if (sopt->ts_needaddr) {
126 if (soffset + 3 > optlen)
128 dopt->ts_needaddr = 1;
131 if (sopt->ts_needtime) {
132 if (soffset + 3 > optlen)
134 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
135 dopt->ts_needtime = 1;
138 dopt->ts_needtime = 0;
140 if (soffset + 7 <= optlen) {
143 memcpy(&addr, dptr+soffset-1, 4);
144 if (inet_addr_type(net, addr) != RTN_UNICAST) {
145 dopt->ts_needtime = 1;
154 dopt->optlen += optlen;
157 unsigned char *start = sptr+sopt->srr;
163 if (soffset > optlen)
164 soffset = optlen + 1;
167 memcpy(&faddr, &start[soffset-1], 4);
168 for (soffset -= 4, doffset = 4; soffset > 3; soffset -= 4, doffset += 4)
169 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
171 * RFC1812 requires to fix illegal source routes.
173 if (memcmp(&ip_hdr(skb)->saddr,
174 &start[soffset + 3], 4) == 0)
183 dopt->srr = dopt->optlen + sizeof(struct iphdr);
184 dopt->optlen += doffset+3;
185 dopt->is_strictroute = sopt->is_strictroute;
189 optlen = sptr[sopt->cipso+1];
190 dopt->cipso = dopt->optlen+sizeof(struct iphdr);
191 memcpy(dptr, sptr+sopt->cipso, optlen);
193 dopt->optlen += optlen;
195 while (dopt->optlen & 3) {
203 * Options "fragmenting", just fill options not
204 * allowed in fragments with NOOPs.
205 * Simple and stupid 8), but the most efficient way.
208 void ip_options_fragment(struct sk_buff *skb)
210 unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
211 struct ip_options *opt = &(IPCB(skb)->opt);
225 if (optlen < 2 || optlen > l)
227 if (!IPOPT_COPIED(*optptr))
228 memset(optptr, IPOPT_NOOP, optlen);
234 opt->rr_needaddr = 0;
235 opt->ts_needaddr = 0;
236 opt->ts_needtime = 0;
239 /* helper used by ip_options_compile() to call fib_compute_spec_dst()
242 static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
244 if (*spec_dst == htonl(INADDR_ANY))
245 *spec_dst = fib_compute_spec_dst(skb);
249 * Verify options and fill pointers in struct options.
250 * Caller should clear *opt, and set opt->data.
251 * If opt == NULL, then skb->data should point to IP header.
254 int __ip_options_compile(struct net *net,
255 struct ip_options *opt, struct sk_buff *skb,
258 __be32 spec_dst = htonl(INADDR_ANY);
259 unsigned char *pp_ptr = NULL;
260 struct rtable *rt = NULL;
261 unsigned char *optptr;
266 rt = skb_rtable(skb);
267 optptr = (unsigned char *)&(ip_hdr(skb)[1]);
269 optptr = opt->__data;
270 iph = optptr - sizeof(struct iphdr);
272 for (l = opt->optlen; l > 0; ) {
275 for (optptr++, l--; l > 0; optptr++, l--) {
276 if (*optptr != IPOPT_END) {
287 if (unlikely(l < 2)) {
292 if (optlen < 2 || optlen > l) {
307 /* NB: cf RFC-1812 5.2.4.1 */
313 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
317 memcpy(&opt->faddr, &optptr[3], 4);
319 memmove(&optptr[3], &optptr[7], optlen-7);
321 opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
322 opt->srr = optptr - iph;
337 if (optptr[2] <= optlen) {
338 if (optptr[2]+3 > optlen) {
343 spec_dst_fill(&spec_dst, skb);
344 memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
348 opt->rr_needaddr = 1;
350 opt->rr = optptr - iph;
352 case IPOPT_TIMESTAMP:
365 if (optptr[2] <= optlen) {
366 unsigned char *timeptr = NULL;
367 if (optptr[2]+3 > optlen) {
371 switch (optptr[3]&0xF) {
372 case IPOPT_TS_TSONLY:
374 timeptr = &optptr[optptr[2]-1];
375 opt->ts_needtime = 1;
378 case IPOPT_TS_TSANDADDR:
379 if (optptr[2]+7 > optlen) {
384 spec_dst_fill(&spec_dst, skb);
385 memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
386 timeptr = &optptr[optptr[2]+3];
388 opt->ts_needaddr = 1;
389 opt->ts_needtime = 1;
392 case IPOPT_TS_PRESPEC:
393 if (optptr[2]+7 > optlen) {
399 memcpy(&addr, &optptr[optptr[2]-1], 4);
400 if (inet_addr_type(net, addr) == RTN_UNICAST)
403 timeptr = &optptr[optptr[2]+3];
405 opt->ts_needtime = 1;
409 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
418 midtime = inet_current_timestamp();
419 memcpy(timeptr, &midtime, 4);
422 } else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) {
423 unsigned int overflow = optptr[3]>>4;
424 if (overflow == 15) {
429 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
433 opt->ts = optptr - iph;
440 if (optptr[2] == 0 && optptr[3] == 0)
441 opt->router_alert = optptr - iph;
444 if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) || opt->cipso) {
448 opt->cipso = optptr - iph;
449 if (cipso_v4_validate(skb, &optptr)) {
457 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
473 *info = htonl((pp_ptr-iph)<<24);
476 EXPORT_SYMBOL(__ip_options_compile);
478 int ip_options_compile(struct net *net,
479 struct ip_options *opt, struct sk_buff *skb)
484 ret = __ip_options_compile(net, opt, skb, &info);
486 icmp_send(skb, ICMP_PARAMETERPROB, 0, info);
489 EXPORT_SYMBOL(ip_options_compile);
492 * Undo all the changes done by ip_options_compile().
495 void ip_options_undo(struct ip_options *opt)
498 unsigned char *optptr = opt->__data + opt->srr - sizeof(struct iphdr);
500 memmove(optptr + 7, optptr + 3, optptr[1] - 7);
501 memcpy(optptr + 3, &opt->faddr, 4);
503 if (opt->rr_needaddr) {
504 unsigned char *optptr = opt->__data + opt->rr - sizeof(struct iphdr);
507 memset(&optptr[optptr[2] - 1], 0, 4);
510 unsigned char *optptr = opt->__data + opt->ts - sizeof(struct iphdr);
512 if (opt->ts_needtime) {
514 memset(&optptr[optptr[2] - 1], 0, 4);
515 if ((optptr[3] & 0xF) == IPOPT_TS_PRESPEC)
518 if (opt->ts_needaddr) {
520 memset(&optptr[optptr[2] - 1], 0, 4);
525 int ip_options_get(struct net *net, struct ip_options_rcu **optp,
526 sockptr_t data, int optlen)
528 struct ip_options_rcu *opt;
530 opt = kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
534 if (optlen && copy_from_sockptr(opt->opt.__data, data, optlen)) {
540 opt->opt.__data[optlen++] = IPOPT_END;
541 opt->opt.optlen = optlen;
542 if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
551 void ip_forward_options(struct sk_buff *skb)
553 struct ip_options *opt = &(IPCB(skb)->opt);
554 unsigned char *optptr;
555 struct rtable *rt = skb_rtable(skb);
556 unsigned char *raw = skb_network_header(skb);
558 if (opt->rr_needaddr) {
559 optptr = (unsigned char *)raw + opt->rr;
560 ip_rt_get_source(&optptr[optptr[2]-5], skb, rt);
563 if (opt->srr_is_hit) {
564 int srrptr, srrspace;
566 optptr = raw + opt->srr;
568 for ( srrptr = optptr[2], srrspace = optptr[1];
572 if (srrptr + 3 > srrspace)
574 if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
577 if (srrptr + 3 <= srrspace) {
579 ip_hdr(skb)->daddr = opt->nexthop;
580 ip_rt_get_source(&optptr[srrptr-1], skb, rt);
581 optptr[2] = srrptr+4;
583 net_crit_ratelimited("%s(): Argh! Destination lost!\n",
586 if (opt->ts_needaddr) {
587 optptr = raw + opt->ts;
588 ip_rt_get_source(&optptr[optptr[2]-9], skb, rt);
592 if (opt->is_changed) {
594 ip_send_check(ip_hdr(skb));
598 int ip_options_rcv_srr(struct sk_buff *skb, struct net_device *dev)
600 struct ip_options *opt = &(IPCB(skb)->opt);
601 int srrspace, srrptr;
603 struct iphdr *iph = ip_hdr(skb);
604 unsigned char *optptr = skb_network_header(skb) + opt->srr;
605 struct rtable *rt = skb_rtable(skb);
607 unsigned long orefdst;
613 if (skb->pkt_type != PACKET_HOST)
615 if (rt->rt_type == RTN_UNICAST) {
616 if (!opt->is_strictroute)
618 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
621 if (rt->rt_type != RTN_LOCAL)
624 for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
625 if (srrptr + 3 > srrspace) {
626 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
629 memcpy(&nexthop, &optptr[srrptr-1], 4);
631 orefdst = skb->_skb_refdst;
632 skb_dst_set(skb, NULL);
633 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, dev);
634 rt2 = skb_rtable(skb);
635 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
637 skb->_skb_refdst = orefdst;
640 refdst_drop(orefdst);
641 if (rt2->rt_type != RTN_LOCAL)
643 /* Superfast 8) loopback forward */
644 iph->daddr = nexthop;
647 if (srrptr <= srrspace) {
649 opt->nexthop = nexthop;
654 EXPORT_SYMBOL(ip_options_rcv_srr);