| 1 | |
| 2 |
|
| 3 |
|
| 4 | |
| 5 |
|
| 6 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
| 7 | #include <linux/module.h>
|
| 8 | #include <linux/skbuff.h>
|
| 9 | #include <linux/in.h>
|
| 10 | #include <linux/ip.h>
|
| 11 |
|
| 12 | #include <linux/netfilter/xt_esp.h>
|
| 13 | #include <linux/netfilter/x_tables.h>
|
| 14 |
|
| 15 | #include <linux/netfilter_ipv4/ip_tables.h>
|
| 16 | #include <linux/netfilter_ipv6/ip6_tables.h>
|
| 17 |
|
| 18 | MODULE_LICENSE("GPL");
|
| 19 | MODULE_AUTHOR("Yon Uriarte <[email protected]>");
|
| 20 | MODULE_DESCRIPTION("Xtables: IPsec-ESP packet match");
|
| 21 | MODULE_ALIAS("ipt_esp");
|
| 22 | MODULE_ALIAS("ip6t_esp");
|
| 23 |
|
| 24 |
|
| 25 | static inline bool
|
| 26 | spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
|
| 27 | {
|
| 28 | return (spi >= min && spi <= max) ^ invert;
|
| 29 | }
|
| 30 |
|
| 31 | static bool esp_mt(const struct sk_buff *skb, struct xt_action_param *par)
|
| 32 | {
|
| 33 | const struct ip_esp_hdr *eh;
|
| 34 | struct ip_esp_hdr _esp;
|
| 35 | const struct xt_esp *espinfo = par->matchinfo;
|
| 36 |
|
| 37 |
|
| 38 | if (par->fragoff != 0)
|
| 39 | return false;
|
| 40 |
|
| 41 | eh = skb_header_pointer(skb, par->thoff, sizeof(_esp), &_esp);
|
| 42 | if (eh == NULL) {
|
| 43 | |
| 44 | * can't. Hence, no choice but to drop.
|
| 45 |
|
| 46 | par->hotdrop = true;
|
| 47 | return false;
|
| 48 | }
|
| 49 |
|
| 50 | return spi_match(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi),
|
| 51 | !!(espinfo->invflags & XT_ESP_INV_SPI));
|
| 52 | }
|
| 53 |
|
| 54 | static int esp_mt_check(const struct xt_mtchk_param *par)
|
| 55 | {
|
| 56 | const struct xt_esp *espinfo = par->matchinfo;
|
| 57 |
|
| 58 | if (espinfo->invflags & ~XT_ESP_INV_MASK) {
|
| 59 | pr_info_ratelimited("unknown flags %X\n", espinfo->invflags);
|
| 60 | return -EINVAL;
|
| 61 | }
|
| 62 |
|
| 63 | return 0;
|
| 64 | }
|
| 65 |
|
| 66 | static struct xt_match esp_mt_reg[] __read_mostly = {
|
| 67 | {
|
| 68 | .name = "esp",
|
| 69 | .family = NFPROTO_IPV4,
|
| 70 | .checkentry = esp_mt_check,
|
| 71 | .match = esp_mt,
|
| 72 | .matchsize = sizeof(struct xt_esp),
|
| 73 | .proto = IPPROTO_ESP,
|
| 74 | .me = THIS_MODULE,
|
| 75 | },
|
| 76 | {
|
| 77 | .name = "esp",
|
| 78 | .family = NFPROTO_IPV6,
|
| 79 | .checkentry = esp_mt_check,
|
| 80 | .match = esp_mt,
|
| 81 | .matchsize = sizeof(struct xt_esp),
|
| 82 | .proto = IPPROTO_ESP,
|
| 83 | .me = THIS_MODULE,
|
| 84 | },
|
| 85 | };
|
| 86 |
|
| 87 | static int __init esp_mt_init(void)
|
| 88 | {
|
| 89 | return xt_register_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
|
| 90 | }
|
| 91 |
|
| 92 | static void __exit esp_mt_exit(void)
|
| 93 | {
|
| 94 | xt_unregister_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
|
| 95 | }
|
| 96 |
|
| 97 | module_init(esp_mt_init);
|
| 98 | module_exit(esp_mt_exit);
|