[linux.git] / net / ipv4 / ip_options.c

// SPDX-License-Identifier: GPL-2.0
/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		The options processing module for ip.c
 *
 * Authors:	A.N.Kuznetsov
 *
 */

#define pr_fmt(fmt) "IPv4: " fmt

#include <linux/capability.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <asm/unaligned.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/route.h>
#include <net/cipso_ipv4.h>
#include <net/ip_fib.h>

/*
 * Write options to IP header, record destination address to
 * source route option, address of outgoing interface
 * (we should already know it, so that this  function is allowed be
 * called only after routing decision) and timestamp,
 * if we originate this datagram.
 *
 * daddr is real destination address, next hop is recorded in IP header.
 * saddr is address of outgoing interface.
 */

void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
		      __be32 daddr, struct rtable *rt, int is_frag)
{
	unsigned char *iph = skb_network_header(skb);

	memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
	memcpy(iph+sizeof(struct iphdr), opt->__data, opt->optlen);
	opt = &(IPCB(skb)->opt);

	if (opt->srr)
		memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);

	if (!is_frag) {
		if (opt->rr_needaddr)
			ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, skb, rt);
		if (opt->ts_needaddr)
			ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, skb, rt);
		if (opt->ts_needtime) {
			__be32 midtime;

			midtime = inet_current_timestamp();
			memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
		}
		return;
	}
	if (opt->rr) {
		memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
		opt->rr = 0;
		opt->rr_needaddr = 0;
	}
	if (opt->ts) {
		memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
		opt->ts = 0;
		opt->ts_needaddr = opt->ts_needtime = 0;
	}
}

/*
 * Provided (sopt, skb) points to received options,
 * build in dopt compiled option set appropriate for answering.
 * i.e. invert SRR option, copy anothers,
 * and grab room in RR/TS options.
 *
 * NOTE: dopt cannot point to skb.
 */

int __ip_options_echo(struct net *net, struct ip_options *dopt,
		      struct sk_buff *skb, const struct ip_options *sopt)
{
	unsigned char *sptr, *dptr;
	int soffset, doffset;
	int	optlen;

	memset(dopt, 0, sizeof(struct ip_options));

	if (sopt->optlen == 0)
		return 0;

	sptr = skb_network_header(skb);
	dptr = dopt->__data;

	if (sopt->rr) {
		optlen  = sptr[sopt->rr+1];
		soffset = sptr[sopt->rr+2];
		dopt->rr = dopt->optlen + sizeof(struct iphdr);
		memcpy(dptr, sptr+sopt->rr, optlen);
		if (sopt->rr_needaddr && soffset <= optlen) {
			if (soffset + 3 > optlen)
				return -EINVAL;
			dptr[2] = soffset + 4;
			dopt->rr_needaddr = 1;
		}
		dptr += optlen;
		dopt->optlen += optlen;
	}
	if (sopt->ts) {
		optlen = sptr[sopt->ts+1];
		soffset = sptr[sopt->ts+2];
		dopt->ts = dopt->optlen + sizeof(struct iphdr);
		memcpy(dptr, sptr+sopt->ts, optlen);
		if (soffset <= optlen) {
			if (sopt->ts_needaddr) {
				if (soffset + 3 > optlen)
					return -EINVAL;
				dopt->ts_needaddr = 1;
				soffset += 4;
			}
			if (sopt->ts_needtime) {
				if (soffset + 3 > optlen)
					return -EINVAL;
				if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
					dopt->ts_needtime = 1;
					soffset += 4;
				} else {
					dopt->ts_needtime = 0;

					if (soffset + 7 <= optlen) {
						__be32 addr;

						memcpy(&addr, dptr+soffset-1, 4);
						if (inet_addr_type(net, addr) != RTN_UNICAST) {
							dopt->ts_needtime = 1;
							soffset += 8;
						}
					}
				}
			}
			dptr[2] = soffset;
		}
		dptr += optlen;
		dopt->optlen += optlen;
	}
	if (sopt->srr) {
		unsigned char *start = sptr+sopt->srr;
		__be32 faddr;

		optlen  = start[1];
		soffset = start[2];
		doffset = 0;
		if (soffset > optlen)
			soffset = optlen + 1;
		soffset -= 4;
		if (soffset > 3) {
			memcpy(&faddr, &start[soffset-1], 4);
			for (soffset -= 4, doffset = 4; soffset > 3; soffset -= 4, doffset += 4)
				memcpy(&dptr[doffset-1], &start[soffset-1], 4);
			/*
			 * RFC1812 requires to fix illegal source routes.
			 */
			if (memcmp(&ip_hdr(skb)->saddr,
				   &start[soffset + 3], 4) == 0)
				doffset -= 4;
		}
		if (doffset > 3) {
			dopt->faddr = faddr;
			dptr[0] = start[0];
			dptr[1] = doffset+3;
			dptr[2] = 4;
			dptr += doffset+3;
			dopt->srr = dopt->optlen + sizeof(struct iphdr);
			dopt->optlen += doffset+3;
			dopt->is_strictroute = sopt->is_strictroute;
		}
	}
	if (sopt->cipso) {
		optlen  = sptr[sopt->cipso+1];
		dopt->cipso = dopt->optlen+sizeof(struct iphdr);
		memcpy(dptr, sptr+sopt->cipso, optlen);
		dptr += optlen;
		dopt->optlen += optlen;
	}
	while (dopt->optlen & 3) {
		*dptr++ = IPOPT_END;
		dopt->optlen++;
	}
	return 0;
}

/*
 *	Options "fragmenting", just fill options not
 *	allowed in fragments with NOOPs.
 *	Simple and stupid 8), but the most efficient way.
 */

void ip_options_fragment(struct sk_buff *skb)
{
	unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
	struct ip_options *opt = &(IPCB(skb)->opt);
	int  l = opt->optlen;
	int  optlen;

	while (l > 0) {
		switch (*optptr) {
		case IPOPT_END:
			return;
		case IPOPT_NOOP:
			l--;
			optptr++;
			continue;
		}
		optlen = optptr[1];
		if (optlen < 2 || optlen > l)
		  return;
		if (!IPOPT_COPIED(*optptr))
			memset(optptr, IPOPT_NOOP, optlen);
		l -= optlen;
		optptr += optlen;
	}
	opt->ts = 0;
	opt->rr = 0;
	opt->rr_needaddr = 0;
	opt->ts_needaddr = 0;
	opt->ts_needtime = 0;
}

/* helper used by ip_options_compile() to call fib_compute_spec_dst()
 * at most one time.
 */
static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
{
	if (*spec_dst == htonl(INADDR_ANY))
		*spec_dst = fib_compute_spec_dst(skb);
}

/*
 * Verify options and fill pointers in struct options.
 * Caller should clear *opt, and set opt->data.
 * If opt == NULL, then skb->data should point to IP header.
 */

int ip_options_compile(struct net *net,
		       struct ip_options *opt, struct sk_buff *skb)
{
	__be32 spec_dst = htonl(INADDR_ANY);
	unsigned char *pp_ptr = NULL;
	struct rtable *rt = NULL;
	unsigned char *optptr;
	unsigned char *iph;
	int optlen, l;

	if (skb) {
		rt = skb_rtable(skb);
		optptr = (unsigned char *)&(ip_hdr(skb)[1]);
	} else
		optptr = opt->__data;
	iph = optptr - sizeof(struct iphdr);

	for (l = opt->optlen; l > 0; ) {
		switch (*optptr) {
		case IPOPT_END:
			for (optptr++, l--; l > 0; optptr++, l--) {
				if (*optptr != IPOPT_END) {
					*optptr = IPOPT_END;
					opt->is_changed = 1;
				}
			}
			goto eol;
		case IPOPT_NOOP:
			l--;
			optptr++;
			continue;
		}
		if (unlikely(l < 2)) {
			pp_ptr = optptr;
			goto error;
		}
		optlen = optptr[1];
		if (optlen < 2 || optlen > l) {
			pp_ptr = optptr;
			goto error;
		}
		switch (*optptr) {
		case IPOPT_SSRR:
		case IPOPT_LSRR:
			if (optlen < 3) {
				pp_ptr = optptr + 1;
				goto error;
			}
			if (optptr[2] < 4) {
				pp_ptr = optptr + 2;
				goto error;
			}
			/* NB: cf RFC-1812 5.2.4.1 */
			if (opt->srr) {
				pp_ptr = optptr;
				goto error;
			}
			if (!skb) {
				if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
					pp_ptr = optptr + 1;
					goto error;
				}
				memcpy(&opt->faddr, &optptr[3], 4);
				if (optlen > 7)
					memmove(&optptr[3], &optptr[7], optlen-7);
			}
			opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
			opt->srr = optptr - iph;
			break;
		case IPOPT_RR:
			if (opt->rr) {
				pp_ptr = optptr;
				goto error;
			}
			if (optlen < 3) {
				pp_ptr = optptr + 1;
				goto error;
			}
			if (optptr[2] < 4) {
				pp_ptr = optptr + 2;
				goto error;
			}
			if (optptr[2] <= optlen) {
				if (optptr[2]+3 > optlen) {
					pp_ptr = optptr + 2;
					goto error;
				}
				if (rt) {
					spec_dst_fill(&spec_dst, skb);
					memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
					opt->is_changed = 1;
				}
				optptr[2] += 4;
				opt->rr_needaddr = 1;
			}
			opt->rr = optptr - iph;
			break;
		case IPOPT_TIMESTAMP:
			if (opt->ts) {
				pp_ptr = optptr;
				goto error;
			}
			if (optlen < 4) {
				pp_ptr = optptr + 1;
				goto error;
			}
			if (optptr[2] < 5) {
				pp_ptr = optptr + 2;
				goto error;
			}
			if (optptr[2] <= optlen) {
				unsigned char *timeptr = NULL;
				if (optptr[2]+3 > optlen) {
					pp_ptr = optptr + 2;
					goto error;
				}
				switch (optptr[3]&0xF) {
				case IPOPT_TS_TSONLY:
					if (skb)
						timeptr = &optptr[optptr[2]-1];
					opt->ts_needtime = 1;
					optptr[2] += 4;
					break;
				case IPOPT_TS_TSANDADDR:
					if (optptr[2]+7 > optlen) {
						pp_ptr = optptr + 2;
						goto error;
					}
					if (rt)  {
						spec_dst_fill(&spec_dst, skb);
						memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
						timeptr = &optptr[optptr[2]+3];
					}
					opt->ts_needaddr = 1;
					opt->ts_needtime = 1;
					optptr[2] += 8;
					break;
				case IPOPT_TS_PRESPEC:
					if (optptr[2]+7 > optlen) {
						pp_ptr = optptr + 2;
						goto error;
					}
					{
						__be32 addr;
						memcpy(&addr, &optptr[optptr[2]-1], 4);
						if (inet_addr_type(net, addr) == RTN_UNICAST)
							break;
						if (skb)
							timeptr = &optptr[optptr[2]+3];
					}
					opt->ts_needtime = 1;
					optptr[2] += 8;
					break;
				default:
					if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
						pp_ptr = optptr + 3;
						goto error;
					}
					break;
				}
				if (timeptr) {
					__be32 midtime;

					midtime = inet_current_timestamp();
					memcpy(timeptr, &midtime, 4);
					opt->is_changed = 1;
				}
			} else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) {
				unsigned int overflow = optptr[3]>>4;
				if (overflow == 15) {
					pp_ptr = optptr + 3;
					goto error;
				}
				if (skb) {
					optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
					opt->is_changed = 1;
				}
			}
			opt->ts = optptr - iph;
			break;
		case IPOPT_RA:
			if (optlen < 4) {
				pp_ptr = optptr + 1;
				goto error;
			}
			if (optptr[2] == 0 && optptr[3] == 0)
				opt->router_alert = optptr - iph;
			break;
		case IPOPT_CIPSO:
			if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) || opt->cipso) {
				pp_ptr = optptr;
				goto error;
			}
			opt->cipso = optptr - iph;
			if (cipso_v4_validate(skb, &optptr)) {
				pp_ptr = optptr;
				goto error;
			}
			break;
		case IPOPT_SEC:
		case IPOPT_SID:
		default:
			if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
				pp_ptr = optptr;
				goto error;
			}
			break;
		}
		l -= optlen;
		optptr += optlen;
	}

eol:
	if (!pp_ptr)
		return 0;

error:
	if (skb) {
		icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
	}
	return -EINVAL;
}
EXPORT_SYMBOL(ip_options_compile);

/*
 *	Undo all the changes done by ip_options_compile().
 */

void ip_options_undo(struct ip_options *opt)
{
	if (opt->srr) {
		unsigned  char *optptr = opt->__data+opt->srr-sizeof(struct  iphdr);
		memmove(optptr+7, optptr+3, optptr[1]-7);
		memcpy(optptr+3, &opt->faddr, 4);
	}
	if (opt->rr_needaddr) {
		unsigned  char *optptr = opt->__data+opt->rr-sizeof(struct  iphdr);
		optptr[2] -= 4;
		memset(&optptr[optptr[2]-1], 0, 4);
	}
	if (opt->ts) {
		unsigned  char *optptr = opt->__data+opt->ts-sizeof(struct  iphdr);
		if (opt->ts_needtime) {
			optptr[2] -= 4;
			memset(&optptr[optptr[2]-1], 0, 4);
			if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
				optptr[2] -= 4;
		}
		if (opt->ts_needaddr) {
			optptr[2] -= 4;
			memset(&optptr[optptr[2]-1], 0, 4);
		}
	}
}

static struct ip_options_rcu *ip_options_get_alloc(const int optlen)
{
	return kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
		       GFP_KERNEL);
}

static int ip_options_get_finish(struct net *net, struct ip_options_rcu **optp,
				 struct ip_options_rcu *opt, int optlen)
{
	while (optlen & 3)
		opt->opt.__data[optlen++] = IPOPT_END;
	opt->opt.optlen = optlen;
	if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
		kfree(opt);
		return -EINVAL;
	}
	kfree(*optp);
	*optp = opt;
	return 0;
}

int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
			     unsigned char __user *data, int optlen)
{
	struct ip_options_rcu *opt = ip_options_get_alloc(optlen);

	if (!opt)
		return -ENOMEM;
	if (optlen && copy_from_user(opt->opt.__data, data, optlen)) {
		kfree(opt);
		return -EFAULT;
	}
	return ip_options_get_finish(net, optp, opt, optlen);
}

int ip_options_get(struct net *net, struct ip_options_rcu **optp,
		   unsigned char *data, int optlen)
{
	struct ip_options_rcu *opt = ip_options_get_alloc(optlen);

	if (!opt)
		return -ENOMEM;
	if (optlen)
		memcpy(opt->opt.__data, data, optlen);
	return ip_options_get_finish(net, optp, opt, optlen);
}

void ip_forward_options(struct sk_buff *skb)
{
	struct   ip_options *opt	= &(IPCB(skb)->opt);
	unsigned char *optptr;
	struct rtable *rt = skb_rtable(skb);
	unsigned char *raw = skb_network_header(skb);

	if (opt->rr_needaddr) {
		optptr = (unsigned char *)raw + opt->rr;
		ip_rt_get_source(&optptr[optptr[2]-5], skb, rt);
		opt->is_changed = 1;
	}
	if (opt->srr_is_hit) {
		int srrptr, srrspace;

		optptr = raw + opt->srr;

		for ( srrptr = optptr[2], srrspace = optptr[1];
		     srrptr <= srrspace;
		     srrptr += 4
		     ) {
			if (srrptr + 3 > srrspace)
				break;
			if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
				break;
		}
		if (srrptr + 3 <= srrspace) {
			opt->is_changed = 1;
			ip_hdr(skb)->daddr = opt->nexthop;
			ip_rt_get_source(&optptr[srrptr-1], skb, rt);
			optptr[2] = srrptr+4;
		} else {
			net_crit_ratelimited("%s(): Argh! Destination lost!\n",
					     __func__);
		}
		if (opt->ts_needaddr) {
			optptr = raw + opt->ts;
			ip_rt_get_source(&optptr[optptr[2]-9], skb, rt);
			opt->is_changed = 1;
		}
	}
	if (opt->is_changed) {
		opt->is_changed = 0;
		ip_send_check(ip_hdr(skb));
	}
}

int ip_options_rcv_srr(struct sk_buff *skb)
{
	struct ip_options *opt = &(IPCB(skb)->opt);
	int srrspace, srrptr;
	__be32 nexthop;
	struct iphdr *iph = ip_hdr(skb);
	unsigned char *optptr = skb_network_header(skb) + opt->srr;
	struct rtable *rt = skb_rtable(skb);
	struct rtable *rt2;
	unsigned long orefdst;
	int err;

	if (!rt)
		return 0;

	if (skb->pkt_type != PACKET_HOST)
		return -EINVAL;
	if (rt->rt_type == RTN_UNICAST) {
		if (!opt->is_strictroute)
			return 0;
		icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
		return -EINVAL;
	}
	if (rt->rt_type != RTN_LOCAL)
		return -EINVAL;

	for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
		if (srrptr + 3 > srrspace) {
			icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
			return -EINVAL;
		}
		memcpy(&nexthop, &optptr[srrptr-1], 4);

		orefdst = skb->_skb_refdst;
		skb_dst_set(skb, NULL);
		err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
		rt2 = skb_rtable(skb);
		if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
			skb_dst_drop(skb);
			skb->_skb_refdst = orefdst;
			return -EINVAL;
		}
		refdst_drop(orefdst);
		if (rt2->rt_type != RTN_LOCAL)
			break;
		/* Superfast 8) loopback forward */
		iph->daddr = nexthop;
		opt->is_changed = 1;
	}
	if (srrptr <= srrspace) {
		opt->srr_is_hit = 1;
		opt->nexthop = nexthop;
		opt->is_changed = 1;
	}
	return 0;
}
EXPORT_SYMBOL(ip_options_rcv_srr);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	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.
	6	*
	7	* The options processing module for ip.c
	8	*
1da177e4	9	* Authors: A.N.Kuznetsov
e905a9ed	10	*
1da177e4 LT	11	*/
1da177e4 LT	12
afd46503 JP	13	#define pr_fmt(fmt) "IPv4: " fmt
afd46503 JP	14
4fc268d2	15	#include <linux/capability.h>
1da177e4	16	#include <linux/module.h>
5a0e3ad6	17	#include <linux/slab.h>
1da177e4	18	#include <linux/types.h>
7c0f6ba6	19	#include <linux/uaccess.h>
48bdf072	20	#include <asm/unaligned.h>
1da177e4 LT	21	#include <linux/skbuff.h>
	22	#include <linux/ip.h>
	23	#include <linux/icmp.h>
	24	#include <linux/netdevice.h>
	25	#include <linux/rtnetlink.h>
	26	#include <net/sock.h>
	27	#include <net/ip.h>
	28	#include <net/icmp.h>
14c85021	29	#include <net/route.h>
11a03f78	30	#include <net/cipso_ipv4.h>
35ebf65e	31	#include <net/ip_fib.h>
1da177e4	32
e905a9ed	33	/*
1da177e4 LT	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.
	39	*
	40	* daddr is real destination address, next hop is recorded in IP header.
	41	* saddr is address of outgoing interface.
	42	*/
	43
f6d8bd05	44	void ip_options_build(struct sk_buff skb, struct ip_options opt,
8e36360a	45	__be32 daddr, struct rtable *rt, int is_frag)
1da177e4	46	{
d56f90a7	47	unsigned char *iph = skb_network_header(skb);
1da177e4 LT	48
	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);
1da177e4 LT	52
	53	if (opt->srr)
	54	memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);
	55
	56	if (!is_frag) {
	57	if (opt->rr_needaddr)
8e36360a	58	ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, skb, rt);
1da177e4	59	if (opt->ts_needaddr)
8e36360a	60	ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, skb, rt);
1da177e4	61	if (opt->ts_needtime) {
e25d2ca6	62	__be32 midtime;
822c8685 DD	63
822c8685 DD	64	midtime = inet_current_timestamp();
1da177e4 LT	65	memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
	66	}
	67	return;
	68	}
	69	if (opt->rr) {
	70	memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
	71	opt->rr = 0;
	72	opt->rr_needaddr = 0;
	73	}
	74	if (opt->ts) {
	75	memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
	76	opt->ts = 0;
	77	opt->ts_needaddr = opt->ts_needtime = 0;
	78	}
	79	}
	80
e905a9ed	81	/*
1da177e4 LT	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.
	86	*
	87	* NOTE: dopt cannot point to skb.
	88	*/
	89
91ed1e66 PA	90	int __ip_options_echo(struct net net, struct ip_options dopt,
91ed1e66 PA	91	struct sk_buff skb, const struct ip_options sopt)
1da177e4	92	{
1da177e4 LT	93	unsigned char sptr, dptr;
	94	int soffset, doffset;
	95	int optlen;
1da177e4 LT	96
	97	memset(dopt, 0, sizeof(struct ip_options));
	98
f6d8bd05	99	if (sopt->optlen == 0)
1da177e4	100	return 0;
1da177e4	101
d56f90a7	102	sptr = skb_network_header(skb);
1da177e4 LT	103	dptr = dopt->__data;
1da177e4 LT	104
1da177e4 LT	105	if (sopt->rr) {
	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)
	112	return -EINVAL;
	113	dptr[2] = soffset + 4;
	114	dopt->rr_needaddr = 1;
	115	}
	116	dptr += optlen;
	117	dopt->optlen += optlen;
	118	}
	119	if (sopt->ts) {
	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)
	127	return -EINVAL;
	128	dopt->ts_needaddr = 1;
	129	soffset += 4;
	130	}
	131	if (sopt->ts_needtime) {
	132	if (soffset + 3 > optlen)
	133	return -EINVAL;
	134	if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
	135	dopt->ts_needtime = 1;
	136	soffset += 4;
	137	} else {
	138	dopt->ts_needtime = 0;
	139
8628bd8a	140	if (soffset + 7 <= optlen) {
fd683222	141	__be32 addr;
1da177e4	142
8628bd8a	143	memcpy(&addr, dptr+soffset-1, 4);
91ed1e66	144	if (inet_addr_type(net, addr) != RTN_UNICAST) {
1da177e4 LT	145	dopt->ts_needtime = 1;
	146	soffset += 8;
	147	}
	148	}
	149	}
	150	}
	151	dptr[2] = soffset;
	152	}
	153	dptr += optlen;
	154	dopt->optlen += optlen;
	155	}
	156	if (sopt->srr) {
f6d8bd05	157	unsigned char *start = sptr+sopt->srr;
3ca3c68e	158	__be32 faddr;
1da177e4 LT	159
	160	optlen = start[1];
	161	soffset = start[2];
	162	doffset = 0;
	163	if (soffset > optlen)
	164	soffset = optlen + 1;
	165	soffset -= 4;
	166	if (soffset > 3) {
	167	memcpy(&faddr, &start[soffset-1], 4);
a22318e8	168	for (soffset -= 4, doffset = 4; soffset > 3; soffset -= 4, doffset += 4)
1da177e4 LT	169	memcpy(&dptr[doffset-1], &start[soffset-1], 4);
	170	/*
	171	* RFC1812 requires to fix illegal source routes.
	172	*/
eddc9ec5 ACM	173	if (memcmp(&ip_hdr(skb)->saddr,
eddc9ec5 ACM	174	&start[soffset + 3], 4) == 0)
1da177e4 LT	175	doffset -= 4;
	176	}
	177	if (doffset > 3) {
1da177e4 LT	178	dopt->faddr = faddr;
	179	dptr[0] = start[0];
	180	dptr[1] = doffset+3;
	181	dptr[2] = 4;
	182	dptr += doffset+3;
	183	dopt->srr = dopt->optlen + sizeof(struct iphdr);
	184	dopt->optlen += doffset+3;
	185	dopt->is_strictroute = sopt->is_strictroute;
	186	}
	187	}
11a03f78 PM	188	if (sopt->cipso) {
	189	optlen = sptr[sopt->cipso+1];
	190	dopt->cipso = dopt->optlen+sizeof(struct iphdr);
	191	memcpy(dptr, sptr+sopt->cipso, optlen);
	192	dptr += optlen;
	193	dopt->optlen += optlen;
	194	}
1da177e4 LT	195	while (dopt->optlen & 3) {
	196	*dptr++ = IPOPT_END;
	197	dopt->optlen++;
	198	}
	199	return 0;
	200	}
	201
	202	/*
	203	* Options "fragmenting", just fill options not
	204	* allowed in fragments with NOOPs.
	205	* Simple and stupid 8), but the most efficient way.
	206	*/
	207
5e73ea1a	208	void ip_options_fragment(struct sk_buff *skb)
1da177e4	209	{
d56f90a7	210	unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
5e73ea1a	211	struct ip_options *opt = &(IPCB(skb)->opt);
1da177e4 LT	212	int l = opt->optlen;
	213	int optlen;
	214
	215	while (l > 0) {
	216	switch (*optptr) {
	217	case IPOPT_END:
	218	return;
	219	case IPOPT_NOOP:
	220	l--;
	221	optptr++;
	222	continue;
	223	}
	224	optlen = optptr[1];
a22318e8	225	if (optlen < 2 \|\| optlen > l)
1da177e4 LT	226	return;
	227	if (!IPOPT_COPIED(*optptr))
	228	memset(optptr, IPOPT_NOOP, optlen);
	229	l -= optlen;
	230	optptr += optlen;
	231	}
	232	opt->ts = 0;
	233	opt->rr = 0;
	234	opt->rr_needaddr = 0;
	235	opt->ts_needaddr = 0;
	236	opt->ts_needtime = 0;
1da177e4 LT	237	}
1da177e4 LT	238
bf5e53e3 ED	239	/* helper used by ip_options_compile() to call fib_compute_spec_dst()
	240	* at most one time.
	241	*/
	242	static void spec_dst_fill(__be32 spec_dst, struct sk_buff skb)
	243	{
	244	if (*spec_dst == htonl(INADDR_ANY))
	245	*spec_dst = fib_compute_spec_dst(skb);
	246	}
	247
1da177e4 LT	248	/*
	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.
	252	*/
	253
0e6bd4a1	254	int ip_options_compile(struct net *net,
5e73ea1a	255	struct ip_options opt, struct sk_buff skb)
1da177e4	256	{
bf5e53e3	257	__be32 spec_dst = htonl(INADDR_ANY);
5e73ea1a	258	unsigned char *pp_ptr = NULL;
11604721	259	struct rtable *rt = NULL;
35ebf65e DM	260	unsigned char *optptr;
	261	unsigned char *iph;
	262	int optlen, l;
1da177e4	263
00db4124	264	if (skb) {
11604721	265	rt = skb_rtable(skb);
22aba383 DL	266	optptr = (unsigned char *)&(ip_hdr(skb)[1]);
22aba383 DL	267	} else
10fe7d85	268	optptr = opt->__data;
22aba383	269	iph = optptr - sizeof(struct iphdr);
1da177e4 LT	270
	271	for (l = opt->optlen; l > 0; ) {
	272	switch (*optptr) {
dd9b4559	273	case IPOPT_END:
a22318e8	274	for (optptr++, l--; l > 0; optptr++, l--) {
1da177e4 LT	275	if (*optptr != IPOPT_END) {
	276	*optptr = IPOPT_END;
	277	opt->is_changed = 1;
	278	}
	279	}
	280	goto eol;
dd9b4559	281	case IPOPT_NOOP:
1da177e4 LT	282	l--;
	283	optptr++;
	284	continue;
	285	}
10ec9472 ED	286	if (unlikely(l < 2)) {
	287	pp_ptr = optptr;
	288	goto error;
	289	}
1da177e4	290	optlen = optptr[1];
a22318e8	291	if (optlen < 2 \|\| optlen > l) {
1da177e4 LT	292	pp_ptr = optptr;
	293	goto error;
	294	}
	295	switch (*optptr) {
dd9b4559 WC	296	case IPOPT_SSRR:
dd9b4559 WC	297	case IPOPT_LSRR:
1da177e4 LT	298	if (optlen < 3) {
	299	pp_ptr = optptr + 1;
	300	goto error;
	301	}
	302	if (optptr[2] < 4) {
	303	pp_ptr = optptr + 2;
	304	goto error;
	305	}
	306	/* NB: cf RFC-1812 5.2.4.1 */
	307	if (opt->srr) {
	308	pp_ptr = optptr;
	309	goto error;
	310	}
	311	if (!skb) {
	312	if (optptr[2] != 4 \|\| optlen < 7 \|\| ((optlen-3) & 3)) {
	313	pp_ptr = optptr + 1;
	314	goto error;
	315	}
	316	memcpy(&opt->faddr, &optptr[3], 4);
	317	if (optlen > 7)
	318	memmove(&optptr[3], &optptr[7], optlen-7);
	319	}
	320	opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
	321	opt->srr = optptr - iph;
	322	break;
dd9b4559	323	case IPOPT_RR:
1da177e4 LT	324	if (opt->rr) {
	325	pp_ptr = optptr;
	326	goto error;
	327	}
	328	if (optlen < 3) {
	329	pp_ptr = optptr + 1;
	330	goto error;
	331	}
	332	if (optptr[2] < 4) {
	333	pp_ptr = optptr + 2;
	334	goto error;
	335	}
	336	if (optptr[2] <= optlen) {
	337	if (optptr[2]+3 > optlen) {
	338	pp_ptr = optptr + 2;
	339	goto error;
	340	}
11604721	341	if (rt) {
bf5e53e3	342	spec_dst_fill(&spec_dst, skb);
35ebf65e	343	memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
1da177e4 LT	344	opt->is_changed = 1;
	345	}
	346	optptr[2] += 4;
	347	opt->rr_needaddr = 1;
	348	}
	349	opt->rr = optptr - iph;
	350	break;
dd9b4559	351	case IPOPT_TIMESTAMP:
1da177e4 LT	352	if (opt->ts) {
	353	pp_ptr = optptr;
	354	goto error;
	355	}
	356	if (optlen < 4) {
	357	pp_ptr = optptr + 1;
	358	goto error;
	359	}
	360	if (optptr[2] < 5) {
	361	pp_ptr = optptr + 2;
	362	goto error;
	363	}
	364	if (optptr[2] <= optlen) {
48bdf072	365	unsigned char *timeptr = NULL;
5a2b646f	366	if (optptr[2]+3 > optlen) {
1da177e4 LT	367	pp_ptr = optptr + 2;
	368	goto error;
	369	}
	370	switch (optptr[3]&0xF) {
dd9b4559	371	case IPOPT_TS_TSONLY:
e905a9ed	372	if (skb)
48bdf072	373	timeptr = &optptr[optptr[2]-1];
1da177e4 LT	374	opt->ts_needtime = 1;
	375	optptr[2] += 4;
	376	break;
dd9b4559	377	case IPOPT_TS_TSANDADDR:
5a2b646f	378	if (optptr[2]+7 > optlen) {
1da177e4 LT	379	pp_ptr = optptr + 2;
	380	goto error;
	381	}
11604721	382	if (rt) {
bf5e53e3	383	spec_dst_fill(&spec_dst, skb);
35ebf65e	384	memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
48bdf072	385	timeptr = &optptr[optptr[2]+3];
1da177e4 LT	386	}
	387	opt->ts_needaddr = 1;
	388	opt->ts_needtime = 1;
	389	optptr[2] += 8;
	390	break;
dd9b4559	391	case IPOPT_TS_PRESPEC:
5a2b646f	392	if (optptr[2]+7 > optlen) {
1da177e4 LT	393	pp_ptr = optptr + 2;
	394	goto error;
	395	}
1da177e4	396	{
fd683222	397	__be32 addr;
1da177e4	398	memcpy(&addr, &optptr[optptr[2]-1], 4);
0e6bd4a1	399	if (inet_addr_type(net, addr) == RTN_UNICAST)
1da177e4 LT	400	break;
1da177e4 LT	401	if (skb)
48bdf072	402	timeptr = &optptr[optptr[2]+3];
1da177e4 LT	403	}
	404	opt->ts_needtime = 1;
	405	optptr[2] += 8;
	406	break;
dd9b4559	407	default:
52e804c6	408	if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
1da177e4 LT	409	pp_ptr = optptr + 3;
	410	goto error;
	411	}
	412	break;
	413	}
	414	if (timeptr) {
822c8685 DD	415	__be32 midtime;
	416
	417	midtime = inet_current_timestamp();
	418	memcpy(timeptr, &midtime, 4);
1da177e4 LT	419	opt->is_changed = 1;
1da177e4 LT	420	}
fa2b04f4	421	} else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) {
95c96174	422	unsigned int overflow = optptr[3]>>4;
1da177e4 LT	423	if (overflow == 15) {
	424	pp_ptr = optptr + 3;
	425	goto error;
	426	}
1da177e4 LT	427	if (skb) {
	428	optptr[3] = (optptr[3]&0xF)\|((overflow+1)<<4);
	429	opt->is_changed = 1;
	430	}
	431	}
4660c7f4	432	opt->ts = optptr - iph;
1da177e4	433	break;
dd9b4559	434	case IPOPT_RA:
1da177e4 LT	435	if (optlen < 4) {
	436	pp_ptr = optptr + 1;
	437	goto error;
	438	}
	439	if (optptr[2] == 0 && optptr[3] == 0)
	440	opt->router_alert = optptr - iph;
	441	break;
dd9b4559	442	case IPOPT_CIPSO:
52e804c6	443	if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) \|\| opt->cipso) {
11a03f78 PM	444	pp_ptr = optptr;
	445	goto error;
	446	}
	447	opt->cipso = optptr - iph;
15c45f7b	448	if (cipso_v4_validate(skb, &optptr)) {
11a03f78 PM	449	pp_ptr = optptr;
	450	goto error;
	451	}
	452	break;
dd9b4559 WC	453	case IPOPT_SEC:
	454	case IPOPT_SID:
	455	default:
52e804c6	456	if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
1da177e4 LT	457	pp_ptr = optptr;
	458	goto error;
	459	}
	460	break;
	461	}
	462	l -= optlen;
	463	optptr += optlen;
	464	}
	465
	466	eol:
	467	if (!pp_ptr)
	468	return 0;
	469
	470	error:
	471	if (skb) {
	472	icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
	473	}
	474	return -EINVAL;
	475	}
462fb2af	476	EXPORT_SYMBOL(ip_options_compile);
1da177e4 LT	477
	478	/*
	479	* Undo all the changes done by ip_options_compile().
	480	*/
	481
5e73ea1a	482	void ip_options_undo(struct ip_options *opt)
1da177e4 LT	483	{
1da177e4 LT	484	if (opt->srr) {
5e73ea1a	485	unsigned char *optptr = opt->__data+opt->srr-sizeof(struct iphdr);
1da177e4 LT	486	memmove(optptr+7, optptr+3, optptr[1]-7);
	487	memcpy(optptr+3, &opt->faddr, 4);
	488	}
	489	if (opt->rr_needaddr) {
5e73ea1a	490	unsigned char *optptr = opt->__data+opt->rr-sizeof(struct iphdr);
1da177e4 LT	491	optptr[2] -= 4;
	492	memset(&optptr[optptr[2]-1], 0, 4);
	493	}
	494	if (opt->ts) {
5e73ea1a	495	unsigned char *optptr = opt->__data+opt->ts-sizeof(struct iphdr);
1da177e4 LT	496	if (opt->ts_needtime) {
	497	optptr[2] -= 4;
	498	memset(&optptr[optptr[2]-1], 0, 4);
	499	if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
	500	optptr[2] -= 4;
	501	}
	502	if (opt->ts_needaddr) {
	503	optptr[2] -= 4;
	504	memset(&optptr[optptr[2]-1], 0, 4);
	505	}
	506	}
	507	}
	508
f6d8bd05	509	static struct ip_options_rcu *ip_options_get_alloc(const int optlen)
1da177e4	510	{
f6d8bd05	511	return kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
37640703	512	GFP_KERNEL);
4c6ea29d	513	}
1da177e4	514
f6d8bd05 ED	515	static int ip_options_get_finish(struct net net, struct ip_options_rcu *optp,
f6d8bd05 ED	516	struct ip_options_rcu *opt, int optlen)
4c6ea29d	517	{
1da177e4	518	while (optlen & 3)
f6d8bd05 ED	519	opt->opt.__data[optlen++] = IPOPT_END;
	520	opt->opt.optlen = optlen;
	521	if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
1da177e4 LT	522	kfree(opt);
	523	return -EINVAL;
	524	}
a51482bd	525	kfree(*optp);
1da177e4 LT	526	*optp = opt;
	527	return 0;
	528	}
	529
f6d8bd05	530	int ip_options_get_from_user(struct net net, struct ip_options_rcu *optp,
f2c4802b	531	unsigned char __user *data, int optlen)
4c6ea29d	532	{
f6d8bd05	533	struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
4c6ea29d ACM	534
	535	if (!opt)
	536	return -ENOMEM;
f6d8bd05	537	if (optlen && copy_from_user(opt->opt.__data, data, optlen)) {
4c6ea29d ACM	538	kfree(opt);
	539	return -EFAULT;
	540	}
f2c4802b	541	return ip_options_get_finish(net, optp, opt, optlen);
4c6ea29d ACM	542	}
4c6ea29d ACM	543
f6d8bd05	544	int ip_options_get(struct net net, struct ip_options_rcu *optp,
f2c4802b	545	unsigned char *data, int optlen)
4c6ea29d	546	{
f6d8bd05	547	struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
4c6ea29d ACM	548
	549	if (!opt)
	550	return -ENOMEM;
	551	if (optlen)
f6d8bd05	552	memcpy(opt->opt.__data, data, optlen);
f2c4802b	553	return ip_options_get_finish(net, optp, opt, optlen);
4c6ea29d ACM	554	}
4c6ea29d ACM	555
1da177e4 LT	556	void ip_forward_options(struct sk_buff *skb)
1da177e4 LT	557	{
5e73ea1a DB	558	struct ip_options *opt = &(IPCB(skb)->opt);
5e73ea1a DB	559	unsigned char *optptr;
511c3f92	560	struct rtable *rt = skb_rtable(skb);
d56f90a7	561	unsigned char *raw = skb_network_header(skb);
1da177e4 LT	562
	563	if (opt->rr_needaddr) {
	564	optptr = (unsigned char *)raw + opt->rr;
8e36360a	565	ip_rt_get_source(&optptr[optptr[2]-5], skb, rt);
1da177e4 LT	566	opt->is_changed = 1;
	567	}
	568	if (opt->srr_is_hit) {
	569	int srrptr, srrspace;
	570
	571	optptr = raw + opt->srr;
	572
a22318e8	573	for ( srrptr = optptr[2], srrspace = optptr[1];
1da177e4 LT	574	srrptr <= srrspace;
	575	srrptr += 4
	576	) {
	577	if (srrptr + 3 > srrspace)
	578	break;
ac8a4810	579	if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
1da177e4 LT	580	break;
	581	}
	582	if (srrptr + 3 <= srrspace) {
	583	opt->is_changed = 1;
ac8a4810	584	ip_hdr(skb)->daddr = opt->nexthop;
5dc7883f	585	ip_rt_get_source(&optptr[srrptr-1], skb, rt);
1da177e4	586	optptr[2] = srrptr+4;
e87cc472 JP	587	} else {
	588	net_crit_ratelimited("%s(): Argh! Destination lost!\n",
	589	__func__);
	590	}
1da177e4 LT	591	if (opt->ts_needaddr) {
1da177e4 LT	592	optptr = raw + opt->ts;
8e36360a	593	ip_rt_get_source(&optptr[optptr[2]-9], skb, rt);
1da177e4 LT	594	opt->is_changed = 1;
	595	}
	596	}
	597	if (opt->is_changed) {
	598	opt->is_changed = 0;
eddc9ec5	599	ip_send_check(ip_hdr(skb));
1da177e4 LT	600	}
	601	}
	602
	603	int ip_options_rcv_srr(struct sk_buff *skb)
	604	{
	605	struct ip_options *opt = &(IPCB(skb)->opt);
	606	int srrspace, srrptr;
9e12bb22	607	__be32 nexthop;
eddc9ec5	608	struct iphdr *iph = ip_hdr(skb);
d56f90a7	609	unsigned char *optptr = skb_network_header(skb) + opt->srr;
511c3f92	610	struct rtable *rt = skb_rtable(skb);
1da177e4	611	struct rtable *rt2;
7fee226a	612	unsigned long orefdst;
1da177e4 LT	613	int err;
1da177e4 LT	614
10949550	615	if (!rt)
1da177e4 LT	616	return 0;
	617
	618	if (skb->pkt_type != PACKET_HOST)
	619	return -EINVAL;
	620	if (rt->rt_type == RTN_UNICAST) {
	621	if (!opt->is_strictroute)
	622	return 0;
	623	icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
	624	return -EINVAL;
	625	}
	626	if (rt->rt_type != RTN_LOCAL)
	627	return -EINVAL;
	628
a22318e8	629	for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
1da177e4 LT	630	if (srrptr + 3 > srrspace) {
	631	icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
	632	return -EINVAL;
	633	}
	634	memcpy(&nexthop, &optptr[srrptr-1], 4);
	635
7fee226a	636	orefdst = skb->_skb_refdst;
adf30907	637	skb_dst_set(skb, NULL);
1da177e4	638	err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
511c3f92	639	rt2 = skb_rtable(skb);
1da177e4	640	if (err \|\| (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
7fee226a ED	641	skb_dst_drop(skb);
7fee226a ED	642	skb->_skb_refdst = orefdst;
1da177e4 LT	643	return -EINVAL;
1da177e4 LT	644	}
7fee226a	645	refdst_drop(orefdst);
1da177e4 LT	646	if (rt2->rt_type != RTN_LOCAL)
	647	break;
	648	/* Superfast 8) loopback forward */
c30883bd	649	iph->daddr = nexthop;
1da177e4 LT	650	opt->is_changed = 1;
	651	}
	652	if (srrptr <= srrspace) {
	653	opt->srr_is_hit = 1;
ac8a4810	654	opt->nexthop = nexthop;
1da177e4 LT	655	opt->is_changed = 1;
	656	}
	657	return 0;
	658	}
462fb2af	659	EXPORT_SYMBOL(ip_options_rcv_srr);