| /* 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); |