Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 1 | /* |
| 2 | * iptables module for DCCP protocol header matching |
| 3 | * |
| 4 | * (C) 2005 by Harald Welte <laforge@netfilter.org> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/module.h> |
| 12 | #include <linux/skbuff.h> |
| 13 | #include <linux/spinlock.h> |
| 14 | #include <net/ip.h> |
| 15 | #include <linux/dccp.h> |
| 16 | |
| 17 | #include <linux/netfilter/x_tables.h> |
| 18 | #include <linux/netfilter/xt_dccp.h> |
| 19 | |
| 20 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 21 | #include <linux/netfilter_ipv6/ip6_tables.h> |
| 22 | |
| 23 | MODULE_LICENSE("GPL"); |
| 24 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
Jan Engelhardt | 2ae15b6 | 2008-01-14 23:42:28 -0800 | [diff] [blame] | 25 | MODULE_DESCRIPTION("Xtables: DCCP protocol packet match"); |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 26 | MODULE_ALIAS("ipt_dccp"); |
Jan Engelhardt | 73aaf93 | 2007-10-11 14:36:40 -0700 | [diff] [blame] | 27 | MODULE_ALIAS("ip6t_dccp"); |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 28 | |
| 29 | #define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \ |
YOSHIFUJI Hideaki | 601e68e | 2007-02-12 11:15:49 -0800 | [diff] [blame] | 30 | || (!!((invflag) & (option)) ^ (cond))) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 31 | |
| 32 | static unsigned char *dccp_optbuf; |
| 33 | static DEFINE_SPINLOCK(dccp_buflock); |
| 34 | |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 35 | static inline bool |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 36 | dccp_find_option(u_int8_t option, |
| 37 | const struct sk_buff *skb, |
| 38 | unsigned int protoff, |
| 39 | const struct dccp_hdr *dh, |
Jan Engelhardt | cff533a | 2007-07-07 22:15:12 -0700 | [diff] [blame] | 40 | bool *hotdrop) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 41 | { |
| 42 | /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */ |
Jan Engelhardt | a47362a | 2007-07-07 22:16:55 -0700 | [diff] [blame] | 43 | const unsigned char *op; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 44 | unsigned int optoff = __dccp_hdr_len(dh); |
| 45 | unsigned int optlen = dh->dccph_doff*4 - __dccp_hdr_len(dh); |
| 46 | unsigned int i; |
| 47 | |
| 48 | if (dh->dccph_doff * 4 < __dccp_hdr_len(dh)) { |
Jan Engelhardt | cff533a | 2007-07-07 22:15:12 -0700 | [diff] [blame] | 49 | *hotdrop = true; |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 50 | return false; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 51 | } |
| 52 | |
| 53 | if (!optlen) |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 54 | return false; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 55 | |
| 56 | spin_lock_bh(&dccp_buflock); |
| 57 | op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf); |
| 58 | if (op == NULL) { |
| 59 | /* If we don't have the whole header, drop packet. */ |
| 60 | spin_unlock_bh(&dccp_buflock); |
Jan Engelhardt | cff533a | 2007-07-07 22:15:12 -0700 | [diff] [blame] | 61 | *hotdrop = true; |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 62 | return false; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 63 | } |
| 64 | |
| 65 | for (i = 0; i < optlen; ) { |
| 66 | if (op[i] == option) { |
| 67 | spin_unlock_bh(&dccp_buflock); |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 68 | return true; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 69 | } |
| 70 | |
YOSHIFUJI Hideaki | 601e68e | 2007-02-12 11:15:49 -0800 | [diff] [blame] | 71 | if (op[i] < 2) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 72 | i++; |
YOSHIFUJI Hideaki | 601e68e | 2007-02-12 11:15:49 -0800 | [diff] [blame] | 73 | else |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 74 | i += op[i+1]?:1; |
| 75 | } |
| 76 | |
| 77 | spin_unlock_bh(&dccp_buflock); |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 78 | return false; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 79 | } |
| 80 | |
| 81 | |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 82 | static inline bool |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 83 | match_types(const struct dccp_hdr *dh, u_int16_t typemask) |
| 84 | { |
Jan Engelhardt | 7c4e36b | 2007-07-07 22:19:08 -0700 | [diff] [blame] | 85 | return typemask & (1 << dh->dccph_type); |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 86 | } |
| 87 | |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 88 | static inline bool |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 89 | match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff, |
Jan Engelhardt | cff533a | 2007-07-07 22:15:12 -0700 | [diff] [blame] | 90 | const struct dccp_hdr *dh, bool *hotdrop) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 91 | { |
| 92 | return dccp_find_option(option, skb, protoff, dh, hotdrop); |
| 93 | } |
| 94 | |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 95 | static bool |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 96 | dccp_mt(const struct sk_buff *skb, const struct net_device *in, |
| 97 | const struct net_device *out, const struct xt_match *match, |
| 98 | const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 99 | { |
Patrick McHardy | 3e72b2f | 2006-05-29 18:19:19 -0700 | [diff] [blame] | 100 | const struct xt_dccp_info *info = matchinfo; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 101 | struct dccp_hdr _dh, *dh; |
| 102 | |
| 103 | if (offset) |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 104 | return false; |
YOSHIFUJI Hideaki | 601e68e | 2007-02-12 11:15:49 -0800 | [diff] [blame] | 105 | |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 106 | dh = skb_header_pointer(skb, protoff, sizeof(_dh), &_dh); |
| 107 | if (dh == NULL) { |
Jan Engelhardt | cff533a | 2007-07-07 22:15:12 -0700 | [diff] [blame] | 108 | *hotdrop = true; |
Jan Engelhardt | 1d93a9c | 2007-07-07 22:15:35 -0700 | [diff] [blame] | 109 | return false; |
YOSHIFUJI Hideaki | 601e68e | 2007-02-12 11:15:49 -0800 | [diff] [blame] | 110 | } |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 111 | |
Jan Engelhardt | 7c4e36b | 2007-07-07 22:19:08 -0700 | [diff] [blame] | 112 | return DCCHECK(ntohs(dh->dccph_sport) >= info->spts[0] |
| 113 | && ntohs(dh->dccph_sport) <= info->spts[1], |
YOSHIFUJI Hideaki | 601e68e | 2007-02-12 11:15:49 -0800 | [diff] [blame] | 114 | XT_DCCP_SRC_PORTS, info->flags, info->invflags) |
Jan Engelhardt | 7c4e36b | 2007-07-07 22:19:08 -0700 | [diff] [blame] | 115 | && DCCHECK(ntohs(dh->dccph_dport) >= info->dpts[0] |
| 116 | && ntohs(dh->dccph_dport) <= info->dpts[1], |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 117 | XT_DCCP_DEST_PORTS, info->flags, info->invflags) |
| 118 | && DCCHECK(match_types(dh, info->typemask), |
| 119 | XT_DCCP_TYPE, info->flags, info->invflags) |
| 120 | && DCCHECK(match_option(info->option, skb, protoff, dh, |
| 121 | hotdrop), |
| 122 | XT_DCCP_OPTION, info->flags, info->invflags); |
| 123 | } |
| 124 | |
Jan Engelhardt | ccb79bd | 2007-07-07 22:16:00 -0700 | [diff] [blame] | 125 | static bool |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 126 | dccp_mt_check(const char *tablename, const void *inf, |
| 127 | const struct xt_match *match, void *matchinfo, |
| 128 | unsigned int hook_mask) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 129 | { |
Patrick McHardy | 5d04bff | 2006-03-20 18:01:58 -0800 | [diff] [blame] | 130 | const struct xt_dccp_info *info = matchinfo; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 131 | |
Patrick McHardy | 5d04bff | 2006-03-20 18:01:58 -0800 | [diff] [blame] | 132 | return !(info->flags & ~XT_DCCP_VALID_FLAGS) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 133 | && !(info->invflags & ~XT_DCCP_VALID_FLAGS) |
| 134 | && !(info->invflags & ~info->flags); |
| 135 | } |
| 136 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 137 | static struct xt_match dccp_mt_reg[] __read_mostly = { |
Patrick McHardy | 4470bbc | 2006-08-22 00:34:04 -0700 | [diff] [blame] | 138 | { |
| 139 | .name = "dccp", |
| 140 | .family = AF_INET, |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 141 | .checkentry = dccp_mt_check, |
| 142 | .match = dccp_mt, |
Patrick McHardy | 4470bbc | 2006-08-22 00:34:04 -0700 | [diff] [blame] | 143 | .matchsize = sizeof(struct xt_dccp_info), |
| 144 | .proto = IPPROTO_DCCP, |
| 145 | .me = THIS_MODULE, |
| 146 | }, |
| 147 | { |
| 148 | .name = "dccp", |
| 149 | .family = AF_INET6, |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 150 | .checkentry = dccp_mt_check, |
| 151 | .match = dccp_mt, |
Patrick McHardy | 4470bbc | 2006-08-22 00:34:04 -0700 | [diff] [blame] | 152 | .matchsize = sizeof(struct xt_dccp_info), |
| 153 | .proto = IPPROTO_DCCP, |
| 154 | .me = THIS_MODULE, |
| 155 | }, |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 156 | }; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 157 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 158 | static int __init dccp_mt_init(void) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 159 | { |
| 160 | int ret; |
| 161 | |
| 162 | /* doff is 8 bits, so the maximum option size is (4*256). Don't put |
| 163 | * this in BSS since DaveM is worried about locked TLB's for kernel |
| 164 | * BSS. */ |
| 165 | dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL); |
| 166 | if (!dccp_optbuf) |
| 167 | return -ENOMEM; |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 168 | ret = xt_register_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg)); |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 169 | if (ret) |
| 170 | goto out_kfree; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 171 | return ret; |
| 172 | |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 173 | out_kfree: |
| 174 | kfree(dccp_optbuf); |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 175 | return ret; |
| 176 | } |
| 177 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 178 | static void __exit dccp_mt_exit(void) |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 179 | { |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 180 | xt_unregister_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg)); |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 181 | kfree(dccp_optbuf); |
| 182 | } |
| 183 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 184 | module_init(dccp_mt_init); |
| 185 | module_exit(dccp_mt_exit); |