summaryrefslogtreecommitdiffstats
path: root/net/ipv4/ip_options.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--net/ipv4/ip_options.c641
1 files changed, 641 insertions, 0 deletions
diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
new file mode 100644
index 000000000..a9e22a098
--- /dev/null
+++ b/net/ipv4/ip_options.c
@@ -0,0 +1,641 @@
+// 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)
+{
+ 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 (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);
+ }
+}
+
+/*
+ * 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 *info)
+{
+ __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 (info)
+ *info = htonl((pp_ptr-iph)<<24);
+ return -EINVAL;
+}
+EXPORT_SYMBOL(__ip_options_compile);
+
+int ip_options_compile(struct net *net,
+ struct ip_options *opt, struct sk_buff *skb)
+{
+ int ret;
+ __be32 info;
+
+ ret = __ip_options_compile(net, opt, skb, &info);
+ if (ret != 0 && skb)
+ icmp_send(skb, ICMP_PARAMETERPROB, 0, info);
+ return ret;
+}
+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);
+ }
+ }
+}
+
+int ip_options_get(struct net *net, struct ip_options_rcu **optp,
+ sockptr_t data, int optlen)
+{
+ struct ip_options_rcu *opt;
+
+ opt = kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
+ GFP_KERNEL);
+ if (!opt)
+ return -ENOMEM;
+ if (optlen && copy_from_sockptr(opt->opt.__data, data, optlen)) {
+ kfree(opt);
+ return -EFAULT;
+ }
+
+ 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;
+}
+
+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 net_device *dev)
+{
+ 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, 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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 17:47:10 +0000