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- /* ipv6header match - matches IPv6 packets based
- on whether they contain certain headers */
- /* Original idea: Brad Chapman
- * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */
- /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
- #include <linux/module.h>
- #include <linux/skbuff.h>
- #include <linux/ipv6.h>
- #include <linux/types.h>
- #include <net/checksum.h>
- #include <net/ipv6.h>
- #include <linux/netfilter/x_tables.h>
- #include <linux/netfilter_ipv6/ip6_tables.h>
- #include <linux/netfilter_ipv6/ip6t_ipv6header.h>
- MODULE_LICENSE("GPL");
- MODULE_DESCRIPTION("Xtables: IPv6 header types match");
- MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
- static bool
- ipv6header_mt6(const struct sk_buff *skb, struct xt_action_param *par)
- {
- const struct ip6t_ipv6header_info *info = par->matchinfo;
- unsigned int temp;
- int len;
- u8 nexthdr;
- unsigned int ptr;
- /* Make sure this isn't an evil packet */
- /* type of the 1st exthdr */
- nexthdr = ipv6_hdr(skb)->nexthdr;
- /* pointer to the 1st exthdr */
- ptr = sizeof(struct ipv6hdr);
- /* available length */
- len = skb->len - ptr;
- temp = 0;
- while (ip6t_ext_hdr(nexthdr)) {
- const struct ipv6_opt_hdr *hp;
- struct ipv6_opt_hdr _hdr;
- int hdrlen;
- /* No more exthdr -> evaluate */
- if (nexthdr == NEXTHDR_NONE) {
- temp |= MASK_NONE;
- break;
- }
- /* Is there enough space for the next ext header? */
- if (len < (int)sizeof(struct ipv6_opt_hdr))
- return false;
- /* ESP -> evaluate */
- if (nexthdr == NEXTHDR_ESP) {
- temp |= MASK_ESP;
- break;
- }
- hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
- BUG_ON(hp == NULL);
- /* Calculate the header length */
- if (nexthdr == NEXTHDR_FRAGMENT)
- hdrlen = 8;
- else if (nexthdr == NEXTHDR_AUTH)
- hdrlen = (hp->hdrlen + 2) << 2;
- else
- hdrlen = ipv6_optlen(hp);
- /* set the flag */
- switch (nexthdr) {
- case NEXTHDR_HOP:
- temp |= MASK_HOPOPTS;
- break;
- case NEXTHDR_ROUTING:
- temp |= MASK_ROUTING;
- break;
- case NEXTHDR_FRAGMENT:
- temp |= MASK_FRAGMENT;
- break;
- case NEXTHDR_AUTH:
- temp |= MASK_AH;
- break;
- case NEXTHDR_DEST:
- temp |= MASK_DSTOPTS;
- break;
- default:
- return false;
- }
- nexthdr = hp->nexthdr;
- len -= hdrlen;
- ptr += hdrlen;
- if (ptr > skb->len)
- break;
- }
- if (nexthdr != NEXTHDR_NONE && nexthdr != NEXTHDR_ESP)
- temp |= MASK_PROTO;
- if (info->modeflag)
- return !((temp ^ info->matchflags ^ info->invflags)
- & info->matchflags);
- else {
- if (info->invflags)
- return temp != info->matchflags;
- else
- return temp == info->matchflags;
- }
- }
- static int ipv6header_mt6_check(const struct xt_mtchk_param *par)
- {
- const struct ip6t_ipv6header_info *info = par->matchinfo;
- /* invflags is 0 or 0xff in hard mode */
- if ((!info->modeflag) && info->invflags != 0x00 &&
- info->invflags != 0xFF)
- return -EINVAL;
- return 0;
- }
- static struct xt_match ipv6header_mt6_reg __read_mostly = {
- .name = "ipv6header",
- .family = NFPROTO_IPV6,
- .match = ipv6header_mt6,
- .matchsize = sizeof(struct ip6t_ipv6header_info),
- .checkentry = ipv6header_mt6_check,
- .destroy = NULL,
- .me = THIS_MODULE,
- };
- static int __init ipv6header_mt6_init(void)
- {
- return xt_register_match(&ipv6header_mt6_reg);
- }
- static void __exit ipv6header_mt6_exit(void)
- {
- xt_unregister_match(&ipv6header_mt6_reg);
- }
- module_init(ipv6header_mt6_init);
- module_exit(ipv6header_mt6_exit);
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