| 1 | |
| 2 | |
| 3 | *
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| 4 | * Copyright (C) 2013 WindRiver
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| 5 | *
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| 6 | * Author:
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| 7 | * Fan Du <[email protected]>
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| 8 | *
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| 9 | * Based on:
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| 10 | * net/netfilter/xt_esp.c
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| 11 |
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| 12 |
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| 13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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| 14 | #include <linux/in.h>
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| 15 | #include <linux/module.h>
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| 16 | #include <linux/skbuff.h>
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| 17 | #include <linux/ip.h>
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| 18 |
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| 19 | #include <linux/netfilter/xt_ipcomp.h>
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| 20 | #include <linux/netfilter/x_tables.h>
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| 21 |
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| 22 | MODULE_LICENSE("GPL");
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| 23 | MODULE_AUTHOR("Fan Du <[email protected]>");
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| 24 | MODULE_DESCRIPTION("Xtables: IPv4/6 IPsec-IPComp SPI match");
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| 25 | MODULE_ALIAS("ipt_ipcomp");
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| 26 | MODULE_ALIAS("ip6t_ipcomp");
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| 27 |
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| 28 |
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| 29 | static inline bool
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| 30 | spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
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| 31 | {
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| 32 | return (spi >= min && spi <= max) ^ invert;
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| 33 | }
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| 34 |
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| 35 | static bool comp_mt(const struct sk_buff *skb, struct xt_action_param *par)
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| 36 | {
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| 37 | struct ip_comp_hdr _comphdr;
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| 38 | const struct ip_comp_hdr *chdr;
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| 39 | const struct xt_ipcomp *compinfo = par->matchinfo;
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| 40 |
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| 41 |
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| 42 | if (par->fragoff != 0)
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| 43 | return false;
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| 44 |
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| 45 | chdr = skb_header_pointer(skb, par->thoff, sizeof(_comphdr), &_comphdr);
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| 46 | if (chdr == NULL) {
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| 47 | |
| 48 | * can't. Hence, no choice but to drop.
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| 49 |
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| 50 | par->hotdrop = true;
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| 51 | return false;
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| 52 | }
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| 53 |
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| 54 | return spi_match(compinfo->spis[0], compinfo->spis[1],
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| 55 | ntohs(chdr->cpi),
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| 56 | !!(compinfo->invflags & XT_IPCOMP_INV_SPI));
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| 57 | }
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| 58 |
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| 59 | static int comp_mt_check(const struct xt_mtchk_param *par)
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| 60 | {
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| 61 | const struct xt_ipcomp *compinfo = par->matchinfo;
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| 62 |
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| 63 |
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| 64 | if (compinfo->invflags & ~XT_IPCOMP_INV_MASK) {
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| 65 | pr_info_ratelimited("unknown flags %X\n", compinfo->invflags);
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| 66 | return -EINVAL;
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| 67 | }
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| 68 | return 0;
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| 69 | }
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| 70 |
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| 71 | static struct xt_match comp_mt_reg[] __read_mostly = {
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| 72 | {
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| 73 | .name = "ipcomp",
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| 74 | .family = NFPROTO_IPV4,
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| 75 | .match = comp_mt,
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| 76 | .matchsize = sizeof(struct xt_ipcomp),
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| 77 | .proto = IPPROTO_COMP,
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| 78 | .checkentry = comp_mt_check,
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| 79 | .me = THIS_MODULE,
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| 80 | },
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| 81 | {
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| 82 | .name = "ipcomp",
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| 83 | .family = NFPROTO_IPV6,
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| 84 | .match = comp_mt,
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| 85 | .matchsize = sizeof(struct xt_ipcomp),
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| 86 | .proto = IPPROTO_COMP,
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| 87 | .checkentry = comp_mt_check,
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| 88 | .me = THIS_MODULE,
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| 89 | },
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| 90 | };
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| 91 |
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| 92 | static int __init comp_mt_init(void)
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| 93 | {
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| 94 | return xt_register_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
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| 95 | }
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| 96 |
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| 97 | static void __exit comp_mt_exit(void)
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| 98 | {
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| 99 | xt_unregister_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
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| 100 | }
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| 101 |
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| 102 | module_init(comp_mt_init);
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| 103 | module_exit(comp_mt_exit);
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