| 6a649f33 |
1 | /* Kernel module to match IPComp parameters for IPv4 and IPv6 |
| 2 | * |
| 3 | * Copyright (C) 2013 WindRiver |
| 4 | * |
| 5 | * Author: |
| 6 | * Fan Du <fan.du@windriver.com> |
| 7 | * |
| 8 | * Based on: |
| 9 | * net/netfilter/xt_esp.c |
| 10 | * |
| 11 | * This program is free software; you can redistribute it and/or |
| 12 | * modify it under the terms of the GNU General Public License |
| 13 | * as published by the Free Software Foundation; either version |
| 14 | * 2 of the License, or (at your option) any later version. |
| 15 | */ |
| 16 | |
| 17 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 18 | #include <linux/in.h> |
| 19 | #include <linux/module.h> |
| 20 | #include <linux/skbuff.h> |
| 21 | #include <linux/ip.h> |
| 22 | |
| 23 | #include <linux/netfilter/xt_ipcomp.h> |
| 24 | #include <linux/netfilter/x_tables.h> |
| 25 | |
| 26 | MODULE_LICENSE("GPL"); |
| 27 | MODULE_AUTHOR("Fan Du <fan.du@windriver.com>"); |
| 28 | MODULE_DESCRIPTION("Xtables: IPv4/6 IPsec-IPComp SPI match"); |
| 29 | |
| 30 | /* Returns 1 if the spi is matched by the range, 0 otherwise */ |
| 31 | static inline bool |
| 32 | spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert) |
| 33 | { |
| 34 | bool r; |
| 35 | pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n", |
| 36 | invert ? '!' : ' ', min, spi, max); |
| 37 | r = (spi >= min && spi <= max) ^ invert; |
| 38 | pr_debug(" result %s\n", r ? "PASS" : "FAILED"); |
| 39 | return r; |
| 40 | } |
| 41 | |
| 42 | static bool comp_mt(const struct sk_buff *skb, struct xt_action_param *par) |
| 43 | { |
| 44 | struct ip_comp_hdr _comphdr; |
| 45 | const struct ip_comp_hdr *chdr; |
| 46 | const struct xt_ipcomp *compinfo = par->matchinfo; |
| 47 | |
| 48 | /* Must not be a fragment. */ |
| 49 | if (par->fragoff != 0) |
| 50 | return false; |
| 51 | |
| 52 | chdr = skb_header_pointer(skb, par->thoff, sizeof(_comphdr), &_comphdr); |
| 53 | if (chdr == NULL) { |
| 54 | /* We've been asked to examine this packet, and we |
| 55 | * can't. Hence, no choice but to drop. |
| 56 | */ |
| 57 | pr_debug("Dropping evil IPComp tinygram.\n"); |
| 58 | par->hotdrop = true; |
| 59 | return 0; |
| 60 | } |
| 61 | |
| 62 | return spi_match(compinfo->spis[0], compinfo->spis[1], |
| 2ba436fc |
63 | ntohs(chdr->cpi), |
| 6a649f33 |
64 | !!(compinfo->invflags & XT_IPCOMP_INV_SPI)); |
| 65 | } |
| 66 | |
| 67 | static int comp_mt_check(const struct xt_mtchk_param *par) |
| 68 | { |
| 69 | const struct xt_ipcomp *compinfo = par->matchinfo; |
| 70 | |
| 71 | /* Must specify no unknown invflags */ |
| 72 | if (compinfo->invflags & ~XT_IPCOMP_INV_MASK) { |
| 73 | pr_err("unknown flags %X\n", compinfo->invflags); |
| 74 | return -EINVAL; |
| 75 | } |
| 76 | return 0; |
| 77 | } |
| 78 | |
| 79 | static struct xt_match comp_mt_reg[] __read_mostly = { |
| 80 | { |
| 81 | .name = "ipcomp", |
| 82 | .family = NFPROTO_IPV4, |
| 83 | .match = comp_mt, |
| 84 | .matchsize = sizeof(struct xt_ipcomp), |
| 85 | .proto = IPPROTO_COMP, |
| 86 | .checkentry = comp_mt_check, |
| 87 | .me = THIS_MODULE, |
| 88 | }, |
| 89 | { |
| 90 | .name = "ipcomp", |
| 91 | .family = NFPROTO_IPV6, |
| 92 | .match = comp_mt, |
| 93 | .matchsize = sizeof(struct xt_ipcomp), |
| 94 | .proto = IPPROTO_COMP, |
| 95 | .checkentry = comp_mt_check, |
| 96 | .me = THIS_MODULE, |
| 97 | }, |
| 98 | }; |
| 99 | |
| 100 | static int __init comp_mt_init(void) |
| 101 | { |
| 102 | return xt_register_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg)); |
| 103 | } |
| 104 | |
| 105 | static void __exit comp_mt_exit(void) |
| 106 | { |
| 107 | xt_unregister_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg)); |
| 108 | } |
| 109 | |
| 110 | module_init(comp_mt_init); |
| 111 | module_exit(comp_mt_exit); |
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