Yasuyuki Kozakai | dc5ab2f | 2006-04-01 02:22:30 -0800 | [diff] [blame] | 1 | /* Kernel module to match ESP parameters. */ |
| 2 | |
| 3 | /* (C) 1999-2000 Yon Uriarte <yon@astaro.de> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License version 2 as |
| 7 | * published by the Free Software Foundation. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/skbuff.h> |
| 12 | #include <linux/in.h> |
| 13 | #include <linux/ip.h> |
| 14 | |
| 15 | #include <linux/netfilter/xt_esp.h> |
| 16 | #include <linux/netfilter/x_tables.h> |
| 17 | |
| 18 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 19 | #include <linux/netfilter_ipv6/ip6_tables.h> |
| 20 | |
| 21 | MODULE_LICENSE("GPL"); |
| 22 | MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>"); |
| 23 | MODULE_DESCRIPTION("x_tables ESP SPI match module"); |
| 24 | MODULE_ALIAS("ipt_esp"); |
| 25 | MODULE_ALIAS("ip6t_esp"); |
| 26 | |
| 27 | #if 0 |
| 28 | #define duprintf(format, args...) printk(format , ## args) |
| 29 | #else |
| 30 | #define duprintf(format, args...) |
| 31 | #endif |
| 32 | |
| 33 | /* Returns 1 if the spi is matched by the range, 0 otherwise */ |
| 34 | static inline int |
| 35 | spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert) |
| 36 | { |
| 37 | int r = 0; |
| 38 | duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ', |
| 39 | min, spi, max); |
| 40 | r = (spi >= min && spi <= max) ^ invert; |
| 41 | duprintf(" result %s\n", r ? "PASS" : "FAILED"); |
| 42 | return r; |
| 43 | } |
| 44 | |
| 45 | static int |
| 46 | match(const struct sk_buff *skb, |
| 47 | const struct net_device *in, |
| 48 | const struct net_device *out, |
| 49 | const struct xt_match *match, |
| 50 | const void *matchinfo, |
| 51 | int offset, |
| 52 | unsigned int protoff, |
Jan Engelhardt | cff533a | 2007-07-07 22:15:12 -0700 | [diff] [blame^] | 53 | bool *hotdrop) |
Yasuyuki Kozakai | dc5ab2f | 2006-04-01 02:22:30 -0800 | [diff] [blame] | 54 | { |
| 55 | struct ip_esp_hdr _esp, *eh; |
| 56 | const struct xt_esp *espinfo = matchinfo; |
| 57 | |
| 58 | /* Must not be a fragment. */ |
| 59 | if (offset) |
| 60 | return 0; |
| 61 | |
| 62 | eh = skb_header_pointer(skb, protoff, sizeof(_esp), &_esp); |
| 63 | if (eh == NULL) { |
| 64 | /* We've been asked to examine this packet, and we |
| 65 | * can't. Hence, no choice but to drop. |
| 66 | */ |
| 67 | duprintf("Dropping evil ESP tinygram.\n"); |
Jan Engelhardt | cff533a | 2007-07-07 22:15:12 -0700 | [diff] [blame^] | 68 | *hotdrop = true; |
Yasuyuki Kozakai | dc5ab2f | 2006-04-01 02:22:30 -0800 | [diff] [blame] | 69 | return 0; |
| 70 | } |
| 71 | |
| 72 | return spi_match(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi), |
| 73 | !!(espinfo->invflags & XT_ESP_INV_SPI)); |
| 74 | } |
| 75 | |
| 76 | /* Called when user tries to insert an entry of this type. */ |
| 77 | static int |
| 78 | checkentry(const char *tablename, |
| 79 | const void *ip_void, |
| 80 | const struct xt_match *match, |
| 81 | void *matchinfo, |
Yasuyuki Kozakai | dc5ab2f | 2006-04-01 02:22:30 -0800 | [diff] [blame] | 82 | unsigned int hook_mask) |
| 83 | { |
| 84 | const struct xt_esp *espinfo = matchinfo; |
| 85 | |
| 86 | if (espinfo->invflags & ~XT_ESP_INV_MASK) { |
| 87 | duprintf("xt_esp: unknown flags %X\n", espinfo->invflags); |
| 88 | return 0; |
| 89 | } |
| 90 | |
| 91 | return 1; |
| 92 | } |
| 93 | |
Patrick McHardy | 4470bbc | 2006-08-22 00:34:04 -0700 | [diff] [blame] | 94 | static struct xt_match xt_esp_match[] = { |
| 95 | { |
| 96 | .name = "esp", |
| 97 | .family = AF_INET, |
| 98 | .checkentry = checkentry, |
| 99 | .match = match, |
| 100 | .matchsize = sizeof(struct xt_esp), |
| 101 | .proto = IPPROTO_ESP, |
| 102 | .me = THIS_MODULE, |
| 103 | }, |
| 104 | { |
| 105 | .name = "esp", |
| 106 | .family = AF_INET6, |
| 107 | .checkentry = checkentry, |
| 108 | .match = match, |
| 109 | .matchsize = sizeof(struct xt_esp), |
| 110 | .proto = IPPROTO_ESP, |
| 111 | .me = THIS_MODULE, |
| 112 | }, |
Yasuyuki Kozakai | dc5ab2f | 2006-04-01 02:22:30 -0800 | [diff] [blame] | 113 | }; |
| 114 | |
| 115 | static int __init xt_esp_init(void) |
| 116 | { |
Patrick McHardy | 4470bbc | 2006-08-22 00:34:04 -0700 | [diff] [blame] | 117 | return xt_register_matches(xt_esp_match, ARRAY_SIZE(xt_esp_match)); |
Yasuyuki Kozakai | dc5ab2f | 2006-04-01 02:22:30 -0800 | [diff] [blame] | 118 | } |
| 119 | |
| 120 | static void __exit xt_esp_cleanup(void) |
| 121 | { |
Patrick McHardy | 4470bbc | 2006-08-22 00:34:04 -0700 | [diff] [blame] | 122 | xt_unregister_matches(xt_esp_match, ARRAY_SIZE(xt_esp_match)); |
Yasuyuki Kozakai | dc5ab2f | 2006-04-01 02:22:30 -0800 | [diff] [blame] | 123 | } |
| 124 | |
| 125 | module_init(xt_esp_init); |
| 126 | module_exit(xt_esp_cleanup); |