// SPDX-License-Identifier: GPL-2.0-only
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/* Kernel module to match ROUTING parameters. */
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/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/ipv6.h>
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#include <linux/types.h>
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#include <net/checksum.h>
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#include <net/ipv6.h>
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#include <asm/byteorder.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#include <linux/netfilter_ipv6/ip6t_rt.h>
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Xtables: IPv6 Routing Header match");
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MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
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/* Returns 1 if the id is matched by the range, 0 otherwise */
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static inline bool
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segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
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{
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return (id >= min && id <= max) ^ invert;
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}
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static bool rt_mt6(const struct sk_buff *skb, struct xt_action_param *par)
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{
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struct ipv6_rt_hdr _route;
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const struct ipv6_rt_hdr *rh;
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const struct ip6t_rt *rtinfo = par->matchinfo;
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unsigned int temp;
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unsigned int ptr = 0;
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unsigned int hdrlen = 0;
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bool ret = false;
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struct in6_addr _addr;
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const struct in6_addr *ap;
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int err;
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err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL, NULL);
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if (err < 0) {
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if (err != -ENOENT)
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par->hotdrop = true;
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return false;
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}
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rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
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if (rh == NULL) {
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par->hotdrop = true;
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return false;
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}
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hdrlen = ipv6_optlen(rh);
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if (skb->len - ptr < hdrlen) {
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/* Pcket smaller than its length field */
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return false;
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}
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ret = (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
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rh->segments_left,
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!!(rtinfo->invflags & IP6T_RT_INV_SGS))) &&
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(!(rtinfo->flags & IP6T_RT_LEN) ||
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((rtinfo->hdrlen == hdrlen) ^
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!!(rtinfo->invflags & IP6T_RT_INV_LEN))) &&
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(!(rtinfo->flags & IP6T_RT_TYP) ||
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((rtinfo->rt_type == rh->type) ^
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!!(rtinfo->invflags & IP6T_RT_INV_TYP)));
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if (ret && (rtinfo->flags & IP6T_RT_RES)) {
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const u_int32_t *rp;
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u_int32_t _reserved;
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rp = skb_header_pointer(skb,
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ptr + offsetof(struct rt0_hdr,
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reserved),
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sizeof(_reserved),
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&_reserved);
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if (!rp) {
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par->hotdrop = true;
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return false;
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}
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ret = (*rp == 0);
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}
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if (!(rtinfo->flags & IP6T_RT_FST)) {
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return ret;
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} else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
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if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
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return false;
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} else {
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unsigned int i = 0;
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for (temp = 0;
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temp < (unsigned int)((hdrlen - 8) / 16);
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temp++) {
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ap = skb_header_pointer(skb,
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ptr
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+ sizeof(struct rt0_hdr)
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+ temp * sizeof(_addr),
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sizeof(_addr),
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&_addr);
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if (ap == NULL) {
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par->hotdrop = true;
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return false;
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}
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if (ipv6_addr_equal(ap, &rtinfo->addrs[i]))
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i++;
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if (i == rtinfo->addrnr)
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break;
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}
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if (i == rtinfo->addrnr)
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return ret;
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else
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return false;
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}
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} else {
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if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
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return false;
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} else {
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for (temp = 0; temp < rtinfo->addrnr; temp++) {
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ap = skb_header_pointer(skb,
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ptr
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+ sizeof(struct rt0_hdr)
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+ temp * sizeof(_addr),
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sizeof(_addr),
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&_addr);
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if (ap == NULL) {
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par->hotdrop = true;
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return false;
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}
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if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
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break;
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}
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if (temp == rtinfo->addrnr &&
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temp == (unsigned int)((hdrlen - 8) / 16))
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return ret;
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else
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return false;
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}
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}
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return false;
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}
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static int rt_mt6_check(const struct xt_mtchk_param *par)
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{
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const struct ip6t_rt *rtinfo = par->matchinfo;
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if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
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pr_debug("unknown flags %X\n", rtinfo->invflags);
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return -EINVAL;
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}
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if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
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(!(rtinfo->flags & IP6T_RT_TYP) ||
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(rtinfo->rt_type != 0) ||
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(rtinfo->invflags & IP6T_RT_INV_TYP))) {
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pr_debug("`--rt-type 0' required before `--rt-0-*'");
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return -EINVAL;
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}
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return 0;
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}
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static struct xt_match rt_mt6_reg __read_mostly = {
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.name = "rt",
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.family = NFPROTO_IPV6,
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.match = rt_mt6,
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.matchsize = sizeof(struct ip6t_rt),
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.checkentry = rt_mt6_check,
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.me = THIS_MODULE,
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};
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static int __init rt_mt6_init(void)
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{
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return xt_register_match(&rt_mt6_reg);
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}
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static void __exit rt_mt6_exit(void)
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{
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xt_unregister_match(&rt_mt6_reg);
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}
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module_init(rt_mt6_init);
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module_exit(rt_mt6_exit);
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