// SPDX-License-Identifier: GPL-2.0-only
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/* ipv6header match - matches IPv6 packets based
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on whether they contain certain headers */
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/* Original idea: Brad Chapman
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* Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */
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/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
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*/
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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 <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/netfilter_ipv6/ip6t_ipv6header.h>
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Xtables: IPv6 header types match");
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MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
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static bool
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ipv6header_mt6(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct ip6t_ipv6header_info *info = par->matchinfo;
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unsigned int temp;
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int len;
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u8 nexthdr;
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unsigned int ptr;
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/* Make sure this isn't an evil packet */
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/* type of the 1st exthdr */
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nexthdr = ipv6_hdr(skb)->nexthdr;
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/* pointer to the 1st exthdr */
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ptr = sizeof(struct ipv6hdr);
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/* available length */
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len = skb->len - ptr;
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temp = 0;
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while (nf_ip6_ext_hdr(nexthdr)) {
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const struct ipv6_opt_hdr *hp;
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struct ipv6_opt_hdr _hdr;
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int hdrlen;
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/* No more exthdr -> evaluate */
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if (nexthdr == NEXTHDR_NONE) {
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temp |= MASK_NONE;
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break;
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}
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/* Is there enough space for the next ext header? */
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if (len < (int)sizeof(struct ipv6_opt_hdr))
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return false;
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/* ESP -> evaluate */
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if (nexthdr == NEXTHDR_ESP) {
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temp |= MASK_ESP;
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break;
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}
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hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
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if (!hp) {
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par->hotdrop = true;
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return false;
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}
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/* Calculate the header length */
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if (nexthdr == NEXTHDR_FRAGMENT)
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hdrlen = 8;
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else if (nexthdr == NEXTHDR_AUTH)
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hdrlen = ipv6_authlen(hp);
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else
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hdrlen = ipv6_optlen(hp);
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/* set the flag */
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switch (nexthdr) {
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case NEXTHDR_HOP:
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temp |= MASK_HOPOPTS;
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break;
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case NEXTHDR_ROUTING:
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temp |= MASK_ROUTING;
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break;
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case NEXTHDR_FRAGMENT:
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temp |= MASK_FRAGMENT;
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break;
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case NEXTHDR_AUTH:
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temp |= MASK_AH;
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break;
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case NEXTHDR_DEST:
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temp |= MASK_DSTOPTS;
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break;
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default:
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return false;
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}
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nexthdr = hp->nexthdr;
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len -= hdrlen;
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ptr += hdrlen;
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if (ptr > skb->len)
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break;
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}
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if (nexthdr != NEXTHDR_NONE && nexthdr != NEXTHDR_ESP)
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temp |= MASK_PROTO;
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if (info->modeflag)
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return !((temp ^ info->matchflags ^ info->invflags)
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& info->matchflags);
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else {
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if (info->invflags)
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return temp != info->matchflags;
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else
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return temp == info->matchflags;
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}
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}
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static int ipv6header_mt6_check(const struct xt_mtchk_param *par)
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{
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const struct ip6t_ipv6header_info *info = par->matchinfo;
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/* invflags is 0 or 0xff in hard mode */
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if ((!info->modeflag) && info->invflags != 0x00 &&
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info->invflags != 0xFF)
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return -EINVAL;
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return 0;
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}
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static struct xt_match ipv6header_mt6_reg __read_mostly = {
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.name = "ipv6header",
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.family = NFPROTO_IPV6,
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.match = ipv6header_mt6,
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.matchsize = sizeof(struct ip6t_ipv6header_info),
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.checkentry = ipv6header_mt6_check,
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.destroy = NULL,
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.me = THIS_MODULE,
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};
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static int __init ipv6header_mt6_init(void)
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{
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return xt_register_match(&ipv6header_mt6_reg);
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}
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static void __exit ipv6header_mt6_exit(void)
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{
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xt_unregister_match(&ipv6header_mt6_reg);
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}
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module_init(ipv6header_mt6_init);
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module_exit(ipv6header_mt6_exit);
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