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- /* Kernel module to match FRAG parameters. */
- /* (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.
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #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_frag.h>
- MODULE_LICENSE("GPL");
- MODULE_DESCRIPTION("Xtables: IPv6 fragment match");
- MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
- /* Returns 1 if the id is matched by the range, 0 otherwise */
- static inline bool
- id_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
- {
- bool r;
- pr_debug("id_match:%c 0x%x <= 0x%x <= 0x%x\n", invert ? '!' : ' ',
- min, id, max);
- r = (id >= min && id <= max) ^ invert;
- pr_debug(" result %s\n", r ? "PASS" : "FAILED");
- return r;
- }
- static bool
- frag_mt6(const struct sk_buff *skb, struct xt_action_param *par)
- {
- struct frag_hdr _frag;
- const struct frag_hdr *fh;
- const struct ip6t_frag *fraginfo = par->matchinfo;
- unsigned int ptr = 0;
- int err;
- err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL, NULL);
- if (err < 0) {
- if (err != -ENOENT)
- par->hotdrop = true;
- return false;
- }
- fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
- if (fh == NULL) {
- par->hotdrop = true;
- return false;
- }
- pr_debug("INFO %04X ", fh->frag_off);
- pr_debug("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
- pr_debug("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
- pr_debug("MF %04X ", fh->frag_off & htons(IP6_MF));
- pr_debug("ID %u %08X\n", ntohl(fh->identification),
- ntohl(fh->identification));
- pr_debug("IPv6 FRAG id %02X ",
- id_match(fraginfo->ids[0], fraginfo->ids[1],
- ntohl(fh->identification),
- !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)));
- pr_debug("res %02X %02X%04X %02X ",
- fraginfo->flags & IP6T_FRAG_RES, fh->reserved,
- ntohs(fh->frag_off) & 0x6,
- !((fraginfo->flags & IP6T_FRAG_RES) &&
- (fh->reserved || (ntohs(fh->frag_off) & 0x06))));
- pr_debug("first %02X %02X %02X ",
- fraginfo->flags & IP6T_FRAG_FST,
- ntohs(fh->frag_off) & ~0x7,
- !((fraginfo->flags & IP6T_FRAG_FST) &&
- (ntohs(fh->frag_off) & ~0x7)));
- pr_debug("mf %02X %02X %02X ",
- fraginfo->flags & IP6T_FRAG_MF,
- ntohs(fh->frag_off) & IP6_MF,
- !((fraginfo->flags & IP6T_FRAG_MF) &&
- !((ntohs(fh->frag_off) & IP6_MF))));
- pr_debug("last %02X %02X %02X\n",
- fraginfo->flags & IP6T_FRAG_NMF,
- ntohs(fh->frag_off) & IP6_MF,
- !((fraginfo->flags & IP6T_FRAG_NMF) &&
- (ntohs(fh->frag_off) & IP6_MF)));
- return (fh != NULL) &&
- id_match(fraginfo->ids[0], fraginfo->ids[1],
- ntohl(fh->identification),
- !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)) &&
- !((fraginfo->flags & IP6T_FRAG_RES) &&
- (fh->reserved || (ntohs(fh->frag_off) & 0x6))) &&
- !((fraginfo->flags & IP6T_FRAG_FST) &&
- (ntohs(fh->frag_off) & ~0x7)) &&
- !((fraginfo->flags & IP6T_FRAG_MF) &&
- !(ntohs(fh->frag_off) & IP6_MF)) &&
- !((fraginfo->flags & IP6T_FRAG_NMF) &&
- (ntohs(fh->frag_off) & IP6_MF));
- }
- static int frag_mt6_check(const struct xt_mtchk_param *par)
- {
- const struct ip6t_frag *fraginfo = par->matchinfo;
- if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
- pr_debug("unknown flags %X\n", fraginfo->invflags);
- return -EINVAL;
- }
- return 0;
- }
- static struct xt_match frag_mt6_reg __read_mostly = {
- .name = "frag",
- .family = NFPROTO_IPV6,
- .match = frag_mt6,
- .matchsize = sizeof(struct ip6t_frag),
- .checkentry = frag_mt6_check,
- .me = THIS_MODULE,
- };
- static int __init frag_mt6_init(void)
- {
- return xt_register_match(&frag_mt6_reg);
- }
- static void __exit frag_mt6_exit(void)
- {
- xt_unregister_match(&frag_mt6_reg);
- }
- module_init(frag_mt6_init);
- module_exit(frag_mt6_exit);
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