diff options
Diffstat (limited to 'net/ipv4/ip_options.c')
| -rw-r--r-- | net/ipv4/ip_options.c | 671 |
1 files changed, 671 insertions, 0 deletions
diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c new file mode 100644 index 000000000..3db31bb9d --- /dev/null +++ b/net/ipv4/ip_options.c @@ -0,0 +1,671 @@ +// 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 *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; +} + +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); + } + } +} + +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 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); |