| /* Kernel module to match AH parameters. */ |
| /* (C) 1999-2000 Yon Uriarte <yon@astaro.de> |
| * |
| * 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/in.h> |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/ip.h> |
| |
| #include <linux/netfilter_ipv4/ipt_ah.h> |
| #include <linux/netfilter/x_tables.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>"); |
| MODULE_DESCRIPTION("Xtables: IPv4 IPsec-AH SPI match"); |
| |
| /* 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_mt(const struct sk_buff *skb, const struct xt_action_param *par) |
| { |
| struct ip_auth_hdr _ahdr; |
| const struct ip_auth_hdr *ah; |
| const struct ipt_ah *ahinfo = par->matchinfo; |
| |
| /* Must not be a fragment. */ |
| if (par->fragoff != 0) |
| return false; |
| |
| ah = skb_header_pointer(skb, par->thoff, sizeof(_ahdr), &_ahdr); |
| if (ah == NULL) { |
| /* We've been asked to examine this packet, and we |
| * can't. Hence, no choice but to drop. |
| */ |
| pr_debug("Dropping evil AH tinygram.\n"); |
| *par->hotdrop = true; |
| return 0; |
| } |
| |
| return spi_match(ahinfo->spis[0], ahinfo->spis[1], |
| ntohl(ah->spi), |
| !!(ahinfo->invflags & IPT_AH_INV_SPI)); |
| } |
| |
| static int ah_mt_check(const struct xt_mtchk_param *par) |
| { |
| const struct ipt_ah *ahinfo = par->matchinfo; |
| |
| /* Must specify no unknown invflags */ |
| if (ahinfo->invflags & ~IPT_AH_INV_MASK) { |
| pr_debug("unknown flags %X\n", ahinfo->invflags); |
| return -EINVAL; |
| } |
| return 0; |
| } |
| |
| static struct xt_match ah_mt_reg __read_mostly = { |
| .name = "ah", |
| .family = NFPROTO_IPV4, |
| .match = ah_mt, |
| .matchsize = sizeof(struct ipt_ah), |
| .proto = IPPROTO_AH, |
| .checkentry = ah_mt_check, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init ah_mt_init(void) |
| { |
| return xt_register_match(&ah_mt_reg); |
| } |
| |
| static void __exit ah_mt_exit(void) |
| { |
| xt_unregister_match(&ah_mt_reg); |
| } |
| |
| module_init(ah_mt_init); |
| module_exit(ah_mt_exit); |