Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* Kernel module to match FRAG parameters. */ |
| 2 | |
| 3 | /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> |
| 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/ipv6.h> |
| 13 | #include <linux/types.h> |
| 14 | #include <net/checksum.h> |
| 15 | #include <net/ipv6.h> |
| 16 | |
| 17 | #include <linux/netfilter_ipv6/ip6_tables.h> |
| 18 | #include <linux/netfilter_ipv6/ip6t_frag.h> |
| 19 | |
| 20 | MODULE_LICENSE("GPL"); |
| 21 | MODULE_DESCRIPTION("IPv6 FRAG match"); |
| 22 | MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); |
| 23 | |
| 24 | #if 0 |
| 25 | #define DEBUGP printk |
| 26 | #else |
| 27 | #define DEBUGP(format, args...) |
| 28 | #endif |
| 29 | |
| 30 | /* Returns 1 if the id is matched by the range, 0 otherwise */ |
| 31 | static inline int |
| 32 | id_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert) |
| 33 | { |
| 34 | int r=0; |
| 35 | DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ', |
| 36 | min,id,max); |
| 37 | r=(id >= min && id <= max) ^ invert; |
| 38 | DEBUGP(" result %s\n",r? "PASS" : "FAILED"); |
| 39 | return r; |
| 40 | } |
| 41 | |
| 42 | static int |
| 43 | match(const struct sk_buff *skb, |
| 44 | const struct net_device *in, |
| 45 | const struct net_device *out, |
| 46 | const void *matchinfo, |
| 47 | int offset, |
| 48 | unsigned int protoff, |
| 49 | int *hotdrop) |
| 50 | { |
Yasuyuki Kozakai | e674d0f | 2005-09-19 15:34:40 -0700 | [diff] [blame] | 51 | struct frag_hdr _frag, *fh; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | const struct ip6t_frag *fraginfo = matchinfo; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 53 | unsigned int ptr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 54 | |
Patrick McHardy | b777e0c | 2006-01-05 12:21:16 -0800 | [diff] [blame] | 55 | if (ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL) < 0) |
Yasuyuki Kozakai | e674d0f | 2005-09-19 15:34:40 -0700 | [diff] [blame] | 56 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | |
Yasuyuki Kozakai | e674d0f | 2005-09-19 15:34:40 -0700 | [diff] [blame] | 58 | fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag); |
| 59 | if (fh == NULL){ |
| 60 | *hotdrop = 1; |
| 61 | return 0; |
| 62 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | |
| 64 | DEBUGP("INFO %04X ", fh->frag_off); |
| 65 | DEBUGP("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7); |
| 66 | DEBUGP("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6); |
| 67 | DEBUGP("MF %04X ", fh->frag_off & htons(IP6_MF)); |
| 68 | DEBUGP("ID %u %08X\n", ntohl(fh->identification), |
| 69 | ntohl(fh->identification)); |
| 70 | |
| 71 | DEBUGP("IPv6 FRAG id %02X ", |
| 72 | (id_match(fraginfo->ids[0], fraginfo->ids[1], |
| 73 | ntohl(fh->identification), |
| 74 | !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)))); |
| 75 | DEBUGP("res %02X %02X%04X %02X ", |
| 76 | (fraginfo->flags & IP6T_FRAG_RES), fh->reserved, |
| 77 | ntohs(fh->frag_off) & 0x6, |
| 78 | !((fraginfo->flags & IP6T_FRAG_RES) |
| 79 | && (fh->reserved || (ntohs(fh->frag_off) & 0x06)))); |
| 80 | DEBUGP("first %02X %02X %02X ", |
| 81 | (fraginfo->flags & IP6T_FRAG_FST), |
| 82 | ntohs(fh->frag_off) & ~0x7, |
| 83 | !((fraginfo->flags & IP6T_FRAG_FST) |
| 84 | && (ntohs(fh->frag_off) & ~0x7))); |
| 85 | DEBUGP("mf %02X %02X %02X ", |
| 86 | (fraginfo->flags & IP6T_FRAG_MF), |
| 87 | ntohs(fh->frag_off) & IP6_MF, |
| 88 | !((fraginfo->flags & IP6T_FRAG_MF) |
| 89 | && !((ntohs(fh->frag_off) & IP6_MF)))); |
| 90 | DEBUGP("last %02X %02X %02X\n", |
| 91 | (fraginfo->flags & IP6T_FRAG_NMF), |
| 92 | ntohs(fh->frag_off) & IP6_MF, |
| 93 | !((fraginfo->flags & IP6T_FRAG_NMF) |
| 94 | && (ntohs(fh->frag_off) & IP6_MF))); |
| 95 | |
| 96 | return (fh != NULL) |
| 97 | && |
| 98 | (id_match(fraginfo->ids[0], fraginfo->ids[1], |
| 99 | ntohl(fh->identification), |
| 100 | !!(fraginfo->invflags & IP6T_FRAG_INV_IDS))) |
| 101 | && |
| 102 | !((fraginfo->flags & IP6T_FRAG_RES) |
| 103 | && (fh->reserved || (ntohs(fh->frag_off) & 0x6))) |
| 104 | && |
| 105 | !((fraginfo->flags & IP6T_FRAG_FST) |
| 106 | && (ntohs(fh->frag_off) & ~0x7)) |
| 107 | && |
| 108 | !((fraginfo->flags & IP6T_FRAG_MF) |
| 109 | && !(ntohs(fh->frag_off) & IP6_MF)) |
| 110 | && |
| 111 | !((fraginfo->flags & IP6T_FRAG_NMF) |
| 112 | && (ntohs(fh->frag_off) & IP6_MF)); |
| 113 | } |
| 114 | |
| 115 | /* Called when user tries to insert an entry of this type. */ |
| 116 | static int |
| 117 | checkentry(const char *tablename, |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame^] | 118 | const void *ip, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 119 | void *matchinfo, |
| 120 | unsigned int matchinfosize, |
| 121 | unsigned int hook_mask) |
| 122 | { |
| 123 | const struct ip6t_frag *fraginfo = matchinfo; |
| 124 | |
| 125 | if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_frag))) { |
| 126 | DEBUGP("ip6t_frag: matchsize %u != %u\n", |
| 127 | matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_frag))); |
| 128 | return 0; |
| 129 | } |
| 130 | if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) { |
| 131 | DEBUGP("ip6t_frag: unknown flags %X\n", |
| 132 | fraginfo->invflags); |
| 133 | return 0; |
| 134 | } |
| 135 | |
| 136 | return 1; |
| 137 | } |
| 138 | |
| 139 | static struct ip6t_match frag_match = { |
| 140 | .name = "frag", |
| 141 | .match = &match, |
| 142 | .checkentry = &checkentry, |
| 143 | .me = THIS_MODULE, |
| 144 | }; |
| 145 | |
| 146 | static int __init init(void) |
| 147 | { |
| 148 | return ip6t_register_match(&frag_match); |
| 149 | } |
| 150 | |
| 151 | static void __exit cleanup(void) |
| 152 | { |
| 153 | ip6t_unregister_match(&frag_match); |
| 154 | } |
| 155 | |
| 156 | module_init(init); |
| 157 | module_exit(cleanup); |