Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 1 | /* |
| 2 | * This is a module which is used for setting the MSS option in TCP packets. |
| 3 | * |
| 4 | * Copyright (C) 2000 Marc Boucher <marc@mbsi.ca> |
| 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/ip.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame^] | 14 | #include <linux/gfp.h> |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 15 | #include <linux/ipv6.h> |
| 16 | #include <linux/tcp.h> |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 17 | #include <net/dst.h> |
| 18 | #include <net/flow.h> |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 19 | #include <net/ipv6.h> |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 20 | #include <net/route.h> |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 21 | #include <net/tcp.h> |
| 22 | |
| 23 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 24 | #include <linux/netfilter_ipv6/ip6_tables.h> |
| 25 | #include <linux/netfilter/x_tables.h> |
| 26 | #include <linux/netfilter/xt_tcpudp.h> |
| 27 | #include <linux/netfilter/xt_TCPMSS.h> |
| 28 | |
| 29 | MODULE_LICENSE("GPL"); |
| 30 | MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>"); |
Jan Engelhardt | 2ae15b6 | 2008-01-14 23:42:28 -0800 | [diff] [blame] | 31 | MODULE_DESCRIPTION("Xtables: TCP Maximum Segment Size (MSS) adjustment"); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 32 | MODULE_ALIAS("ipt_TCPMSS"); |
| 33 | MODULE_ALIAS("ip6t_TCPMSS"); |
| 34 | |
| 35 | static inline unsigned int |
| 36 | optlen(const u_int8_t *opt, unsigned int offset) |
| 37 | { |
| 38 | /* Beware zero-length options: make finite progress */ |
| 39 | if (opt[offset] <= TCPOPT_NOP || opt[offset+1] == 0) |
| 40 | return 1; |
| 41 | else |
| 42 | return opt[offset+1]; |
| 43 | } |
| 44 | |
| 45 | static int |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 46 | tcpmss_mangle_packet(struct sk_buff *skb, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 47 | const struct xt_tcpmss_info *info, |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 48 | unsigned int in_mtu, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 49 | unsigned int tcphoff, |
| 50 | unsigned int minlen) |
| 51 | { |
| 52 | struct tcphdr *tcph; |
| 53 | unsigned int tcplen, i; |
| 54 | __be16 oldval; |
| 55 | u16 newmss; |
| 56 | u8 *opt; |
| 57 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 58 | if (!skb_make_writable(skb, skb->len)) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 59 | return -1; |
| 60 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 61 | tcplen = skb->len - tcphoff; |
| 62 | tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 63 | |
Simon Arlott | 10a1993 | 2010-02-02 15:33:38 +0100 | [diff] [blame] | 64 | /* Header cannot be larger than the packet */ |
| 65 | if (tcplen < tcph->doff*4) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 66 | return -1; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 67 | |
| 68 | if (info->mss == XT_TCPMSS_CLAMP_PMTU) { |
Eric Dumazet | adf3090 | 2009-06-02 05:19:30 +0000 | [diff] [blame] | 69 | if (dst_mtu(skb_dst(skb)) <= minlen) { |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 70 | if (net_ratelimit()) |
| 71 | printk(KERN_ERR "xt_TCPMSS: " |
| 72 | "unknown or invalid path-MTU (%u)\n", |
Eric Dumazet | adf3090 | 2009-06-02 05:19:30 +0000 | [diff] [blame] | 73 | dst_mtu(skb_dst(skb))); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 74 | return -1; |
| 75 | } |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 76 | if (in_mtu <= minlen) { |
| 77 | if (net_ratelimit()) |
| 78 | printk(KERN_ERR "xt_TCPMSS: unknown or " |
| 79 | "invalid path-MTU (%u)\n", in_mtu); |
| 80 | return -1; |
| 81 | } |
Eric Dumazet | adf3090 | 2009-06-02 05:19:30 +0000 | [diff] [blame] | 82 | newmss = min(dst_mtu(skb_dst(skb)), in_mtu) - minlen; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 83 | } else |
| 84 | newmss = info->mss; |
| 85 | |
| 86 | opt = (u_int8_t *)tcph; |
| 87 | for (i = sizeof(struct tcphdr); i < tcph->doff*4; i += optlen(opt, i)) { |
| 88 | if (opt[i] == TCPOPT_MSS && tcph->doff*4 - i >= TCPOLEN_MSS && |
| 89 | opt[i+1] == TCPOLEN_MSS) { |
| 90 | u_int16_t oldmss; |
| 91 | |
| 92 | oldmss = (opt[i+2] << 8) | opt[i+3]; |
| 93 | |
Benjamin LaHaise | 1700806 | 2007-12-17 22:27:36 -0800 | [diff] [blame] | 94 | /* Never increase MSS, even when setting it, as |
| 95 | * doing so results in problems for hosts that rely |
| 96 | * on MSS being set correctly. |
| 97 | */ |
| 98 | if (oldmss <= newmss) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 99 | return 0; |
| 100 | |
| 101 | opt[i+2] = (newmss & 0xff00) >> 8; |
Jan Engelhardt | 7c4e36b | 2007-07-07 22:19:08 -0700 | [diff] [blame] | 102 | opt[i+3] = newmss & 0x00ff; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 103 | |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 104 | inet_proto_csum_replace2(&tcph->check, skb, |
| 105 | htons(oldmss), htons(newmss), |
| 106 | 0); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 107 | return 0; |
| 108 | } |
| 109 | } |
| 110 | |
Simon Arlott | 10a1993 | 2010-02-02 15:33:38 +0100 | [diff] [blame] | 111 | /* There is data after the header so the option can't be added |
| 112 | without moving it, and doing so may make the SYN packet |
| 113 | itself too large. Accept the packet unmodified instead. */ |
| 114 | if (tcplen > tcph->doff*4) |
| 115 | return 0; |
| 116 | |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 117 | /* |
| 118 | * MSS Option not found ?! add it.. |
| 119 | */ |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 120 | if (skb_tailroom(skb) < TCPOLEN_MSS) { |
| 121 | if (pskb_expand_head(skb, 0, |
| 122 | TCPOLEN_MSS - skb_tailroom(skb), |
Herbert Xu | 2ca7b0a | 2007-10-14 00:39:55 -0700 | [diff] [blame] | 123 | GFP_ATOMIC)) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 124 | return -1; |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 125 | tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 126 | } |
| 127 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 128 | skb_put(skb, TCPOLEN_MSS); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 129 | |
| 130 | opt = (u_int8_t *)tcph + sizeof(struct tcphdr); |
| 131 | memmove(opt + TCPOLEN_MSS, opt, tcplen - sizeof(struct tcphdr)); |
| 132 | |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 133 | inet_proto_csum_replace2(&tcph->check, skb, |
| 134 | htons(tcplen), htons(tcplen + TCPOLEN_MSS), 1); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 135 | opt[0] = TCPOPT_MSS; |
| 136 | opt[1] = TCPOLEN_MSS; |
| 137 | opt[2] = (newmss & 0xff00) >> 8; |
Jan Engelhardt | 7c4e36b | 2007-07-07 22:19:08 -0700 | [diff] [blame] | 138 | opt[3] = newmss & 0x00ff; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 139 | |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 140 | inet_proto_csum_replace4(&tcph->check, skb, 0, *((__be32 *)opt), 0); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 141 | |
| 142 | oldval = ((__be16 *)tcph)[6]; |
| 143 | tcph->doff += TCPOLEN_MSS/4; |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 144 | inet_proto_csum_replace2(&tcph->check, skb, |
| 145 | oldval, ((__be16 *)tcph)[6], 0); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 146 | return TCPOLEN_MSS; |
| 147 | } |
| 148 | |
Jan Engelhardt | db1a75b | 2008-07-21 10:02:59 -0700 | [diff] [blame] | 149 | static u_int32_t tcpmss_reverse_mtu(const struct sk_buff *skb, |
| 150 | unsigned int family) |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 151 | { |
Jan Engelhardt | db1a75b | 2008-07-21 10:02:59 -0700 | [diff] [blame] | 152 | struct flowi fl = {}; |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 153 | const struct nf_afinfo *ai; |
| 154 | struct rtable *rt = NULL; |
| 155 | u_int32_t mtu = ~0U; |
| 156 | |
Jan Engelhardt | db1a75b | 2008-07-21 10:02:59 -0700 | [diff] [blame] | 157 | if (family == PF_INET) |
| 158 | fl.fl4_dst = ip_hdr(skb)->saddr; |
| 159 | else |
| 160 | fl.fl6_dst = ipv6_hdr(skb)->saddr; |
| 161 | |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 162 | rcu_read_lock(); |
Jan Engelhardt | db1a75b | 2008-07-21 10:02:59 -0700 | [diff] [blame] | 163 | ai = nf_get_afinfo(family); |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 164 | if (ai != NULL) |
| 165 | ai->route((struct dst_entry **)&rt, &fl); |
| 166 | rcu_read_unlock(); |
| 167 | |
| 168 | if (rt != NULL) { |
| 169 | mtu = dst_mtu(&rt->u.dst); |
| 170 | dst_release(&rt->u.dst); |
| 171 | } |
| 172 | return mtu; |
| 173 | } |
| 174 | |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 175 | static unsigned int |
Jan Engelhardt | 7eb3558 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 176 | tcpmss_tg4(struct sk_buff *skb, const struct xt_target_param *par) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 177 | { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 178 | struct iphdr *iph = ip_hdr(skb); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 179 | __be16 newlen; |
| 180 | int ret; |
| 181 | |
Jan Engelhardt | 7eb3558 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 182 | ret = tcpmss_mangle_packet(skb, par->targinfo, |
Jan Engelhardt | db1a75b | 2008-07-21 10:02:59 -0700 | [diff] [blame] | 183 | tcpmss_reverse_mtu(skb, PF_INET), |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 184 | iph->ihl * 4, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 185 | sizeof(*iph) + sizeof(struct tcphdr)); |
| 186 | if (ret < 0) |
| 187 | return NF_DROP; |
| 188 | if (ret > 0) { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 189 | iph = ip_hdr(skb); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 190 | newlen = htons(ntohs(iph->tot_len) + ret); |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 191 | csum_replace2(&iph->check, iph->tot_len, newlen); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 192 | iph->tot_len = newlen; |
| 193 | } |
| 194 | return XT_CONTINUE; |
| 195 | } |
| 196 | |
| 197 | #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE) |
| 198 | static unsigned int |
Jan Engelhardt | 7eb3558 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 199 | tcpmss_tg6(struct sk_buff *skb, const struct xt_target_param *par) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 200 | { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 201 | struct ipv6hdr *ipv6h = ipv6_hdr(skb); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 202 | u8 nexthdr; |
| 203 | int tcphoff; |
| 204 | int ret; |
| 205 | |
| 206 | nexthdr = ipv6h->nexthdr; |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 207 | tcphoff = ipv6_skip_exthdr(skb, sizeof(*ipv6h), &nexthdr); |
Patrick McHardy | 9dc0564 | 2007-11-30 23:58:03 +1100 | [diff] [blame] | 208 | if (tcphoff < 0) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 209 | return NF_DROP; |
Jan Engelhardt | 7eb3558 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 210 | ret = tcpmss_mangle_packet(skb, par->targinfo, |
Jan Engelhardt | db1a75b | 2008-07-21 10:02:59 -0700 | [diff] [blame] | 211 | tcpmss_reverse_mtu(skb, PF_INET6), |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 212 | tcphoff, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 213 | sizeof(*ipv6h) + sizeof(struct tcphdr)); |
| 214 | if (ret < 0) |
| 215 | return NF_DROP; |
| 216 | if (ret > 0) { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 217 | ipv6h = ipv6_hdr(skb); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 218 | ipv6h->payload_len = htons(ntohs(ipv6h->payload_len) + ret); |
| 219 | } |
| 220 | return XT_CONTINUE; |
| 221 | } |
| 222 | #endif |
| 223 | |
| 224 | #define TH_SYN 0x02 |
| 225 | |
| 226 | /* Must specify -p tcp --syn */ |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 227 | static inline bool find_syn_match(const struct xt_entry_match *m) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 228 | { |
| 229 | const struct xt_tcp *tcpinfo = (const struct xt_tcp *)m->data; |
| 230 | |
| 231 | if (strcmp(m->u.kernel.match->name, "tcp") == 0 && |
| 232 | tcpinfo->flg_cmp & TH_SYN && |
| 233 | !(tcpinfo->invflags & XT_TCP_INV_FLAGS)) |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 234 | return true; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 235 | |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 236 | return false; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 237 | } |
| 238 | |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 239 | static bool tcpmss_tg4_check(const struct xt_tgchk_param *par) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 240 | { |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 241 | const struct xt_tcpmss_info *info = par->targinfo; |
| 242 | const struct ipt_entry *e = par->entryinfo; |
Jan Engelhardt | dcea992 | 2010-02-24 18:34:48 +0100 | [diff] [blame] | 243 | const struct xt_entry_match *ematch; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 244 | |
| 245 | if (info->mss == XT_TCPMSS_CLAMP_PMTU && |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 246 | (par->hook_mask & ~((1 << NF_INET_FORWARD) | |
Patrick McHardy | 6e23ae2 | 2007-11-19 18:53:30 -0800 | [diff] [blame] | 247 | (1 << NF_INET_LOCAL_OUT) | |
| 248 | (1 << NF_INET_POST_ROUTING))) != 0) { |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 249 | printk("xt_TCPMSS: path-MTU clamping only supported in " |
| 250 | "FORWARD, OUTPUT and POSTROUTING hooks\n"); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 251 | return false; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 252 | } |
Jan Engelhardt | dcea992 | 2010-02-24 18:34:48 +0100 | [diff] [blame] | 253 | xt_ematch_foreach(ematch, e) |
| 254 | if (find_syn_match(ematch)) |
| 255 | return true; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 256 | printk("xt_TCPMSS: Only works on TCP SYN packets\n"); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 257 | return false; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 258 | } |
| 259 | |
| 260 | #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE) |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 261 | static bool tcpmss_tg6_check(const struct xt_tgchk_param *par) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 262 | { |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 263 | const struct xt_tcpmss_info *info = par->targinfo; |
| 264 | const struct ip6t_entry *e = par->entryinfo; |
Jan Engelhardt | dcea992 | 2010-02-24 18:34:48 +0100 | [diff] [blame] | 265 | const struct xt_entry_match *ematch; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 266 | |
| 267 | if (info->mss == XT_TCPMSS_CLAMP_PMTU && |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 268 | (par->hook_mask & ~((1 << NF_INET_FORWARD) | |
Patrick McHardy | 6e23ae2 | 2007-11-19 18:53:30 -0800 | [diff] [blame] | 269 | (1 << NF_INET_LOCAL_OUT) | |
| 270 | (1 << NF_INET_POST_ROUTING))) != 0) { |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 271 | printk("xt_TCPMSS: path-MTU clamping only supported in " |
| 272 | "FORWARD, OUTPUT and POSTROUTING hooks\n"); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 273 | return false; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 274 | } |
Jan Engelhardt | dcea992 | 2010-02-24 18:34:48 +0100 | [diff] [blame] | 275 | xt_ematch_foreach(ematch, e) |
| 276 | if (find_syn_match(ematch)) |
| 277 | return true; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 278 | printk("xt_TCPMSS: Only works on TCP SYN packets\n"); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 279 | return false; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 280 | } |
| 281 | #endif |
| 282 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 283 | static struct xt_target tcpmss_tg_reg[] __read_mostly = { |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 284 | { |
Jan Engelhardt | ee999d8 | 2008-10-08 11:35:01 +0200 | [diff] [blame] | 285 | .family = NFPROTO_IPV4, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 286 | .name = "TCPMSS", |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 287 | .checkentry = tcpmss_tg4_check, |
| 288 | .target = tcpmss_tg4, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 289 | .targetsize = sizeof(struct xt_tcpmss_info), |
| 290 | .proto = IPPROTO_TCP, |
| 291 | .me = THIS_MODULE, |
| 292 | }, |
| 293 | #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE) |
| 294 | { |
Jan Engelhardt | ee999d8 | 2008-10-08 11:35:01 +0200 | [diff] [blame] | 295 | .family = NFPROTO_IPV6, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 296 | .name = "TCPMSS", |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 297 | .checkentry = tcpmss_tg6_check, |
| 298 | .target = tcpmss_tg6, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 299 | .targetsize = sizeof(struct xt_tcpmss_info), |
| 300 | .proto = IPPROTO_TCP, |
| 301 | .me = THIS_MODULE, |
| 302 | }, |
| 303 | #endif |
| 304 | }; |
| 305 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 306 | static int __init tcpmss_tg_init(void) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 307 | { |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 308 | return xt_register_targets(tcpmss_tg_reg, ARRAY_SIZE(tcpmss_tg_reg)); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 309 | } |
| 310 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 311 | static void __exit tcpmss_tg_exit(void) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 312 | { |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 313 | xt_unregister_targets(tcpmss_tg_reg, ARRAY_SIZE(tcpmss_tg_reg)); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 314 | } |
| 315 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 316 | module_init(tcpmss_tg_init); |
| 317 | module_exit(tcpmss_tg_exit); |