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- /* Kernel module to match AH 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/ip.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_ah.h>
- MODULE_LICENSE("GPL");
- MODULE_DESCRIPTION("Xtables: IPv6 IPsec-AH match");
- MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
- /* Returns 1 if the spi is matched by the range, 0 otherwise */
- static inline bool
- spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
- {
- bool r;
- pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
- invert ? '!' : ' ', min, spi, max);
- r = (spi >= min && spi <= max) ^ invert;
- pr_debug(" result %s\n", r ? "PASS" : "FAILED");
- return r;
- }
- static bool ah_mt6(const struct sk_buff *skb, struct xt_action_param *par)
- {
- struct ip_auth_hdr _ah;
- const struct ip_auth_hdr *ah;
- const struct ip6t_ah *ahinfo = par->matchinfo;
- unsigned int ptr = 0;
- unsigned int hdrlen = 0;
- int err;
- err = ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH, NULL, NULL);
- if (err < 0) {
- if (err != -ENOENT)
- par->hotdrop = true;
- return false;
- }
- ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
- if (ah == NULL) {
- par->hotdrop = true;
- return false;
- }
- hdrlen = (ah->hdrlen + 2) << 2;
- pr_debug("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
- pr_debug("RES %04X ", ah->reserved);
- pr_debug("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi));
- pr_debug("IPv6 AH spi %02X ",
- spi_match(ahinfo->spis[0], ahinfo->spis[1],
- ntohl(ah->spi),
- !!(ahinfo->invflags & IP6T_AH_INV_SPI)));
- pr_debug("len %02X %04X %02X ",
- ahinfo->hdrlen, hdrlen,
- (!ahinfo->hdrlen ||
- (ahinfo->hdrlen == hdrlen) ^
- !!(ahinfo->invflags & IP6T_AH_INV_LEN)));
- pr_debug("res %02X %04X %02X\n",
- ahinfo->hdrres, ah->reserved,
- !(ahinfo->hdrres && ah->reserved));
- return (ah != NULL) &&
- spi_match(ahinfo->spis[0], ahinfo->spis[1],
- ntohl(ah->spi),
- !!(ahinfo->invflags & IP6T_AH_INV_SPI)) &&
- (!ahinfo->hdrlen ||
- (ahinfo->hdrlen == hdrlen) ^
- !!(ahinfo->invflags & IP6T_AH_INV_LEN)) &&
- !(ahinfo->hdrres && ah->reserved);
- }
- static int ah_mt6_check(const struct xt_mtchk_param *par)
- {
- const struct ip6t_ah *ahinfo = par->matchinfo;
- if (ahinfo->invflags & ~IP6T_AH_INV_MASK) {
- pr_debug("unknown flags %X\n", ahinfo->invflags);
- return -EINVAL;
- }
- return 0;
- }
- static struct xt_match ah_mt6_reg __read_mostly = {
- .name = "ah",
- .family = NFPROTO_IPV6,
- .match = ah_mt6,
- .matchsize = sizeof(struct ip6t_ah),
- .checkentry = ah_mt6_check,
- .me = THIS_MODULE,
- };
- static int __init ah_mt6_init(void)
- {
- return xt_register_match(&ah_mt6_reg);
- }
- static void __exit ah_mt6_exit(void)
- {
- xt_unregister_match(&ah_mt6_reg);
- }
- module_init(ah_mt6_init);
- module_exit(ah_mt6_exit);
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