diff options
Diffstat (limited to 'net/ipv4/netfilter/ipt_TCPMSS.c')
| -rw-r--r-- | net/ipv4/netfilter/ipt_TCPMSS.c | 207 |
1 files changed, 0 insertions, 207 deletions
diff --git a/net/ipv4/netfilter/ipt_TCPMSS.c b/net/ipv4/netfilter/ipt_TCPMSS.c deleted file mode 100644 index 93eb5c3c1884..000000000000 --- a/net/ipv4/netfilter/ipt_TCPMSS.c +++ /dev/null @@ -1,207 +0,0 @@ -/* - * This is a module which is used for setting the MSS option in TCP packets. - * - * Copyright (C) 2000 Marc Boucher <marc@mbsi.ca> - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - */ - -#include <linux/module.h> -#include <linux/skbuff.h> - -#include <linux/ip.h> -#include <net/tcp.h> - -#include <linux/netfilter_ipv4/ip_tables.h> -#include <linux/netfilter_ipv4/ipt_TCPMSS.h> - -MODULE_LICENSE("GPL"); -MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>"); -MODULE_DESCRIPTION("iptables TCP MSS modification module"); - -static inline unsigned int -optlen(const u_int8_t *opt, unsigned int offset) -{ - /* Beware zero-length options: make finite progress */ - if (opt[offset] <= TCPOPT_NOP || opt[offset+1] == 0) - return 1; - else - return opt[offset+1]; -} - -static unsigned int -ipt_tcpmss_target(struct sk_buff **pskb, - const struct net_device *in, - const struct net_device *out, - unsigned int hooknum, - const struct xt_target *target, - const void *targinfo) -{ - const struct ipt_tcpmss_info *tcpmssinfo = targinfo; - struct tcphdr *tcph; - struct iphdr *iph; - u_int16_t tcplen, newmss; - __be16 newtotlen, oldval; - unsigned int i; - u_int8_t *opt; - - if (!skb_make_writable(pskb, (*pskb)->len)) - return NF_DROP; - - iph = (*pskb)->nh.iph; - tcplen = (*pskb)->len - iph->ihl*4; - tcph = (void *)iph + iph->ihl*4; - - /* Since it passed flags test in tcp match, we know it is is - not a fragment, and has data >= tcp header length. SYN - packets should not contain data: if they did, then we risk - running over MTU, sending Frag Needed and breaking things - badly. --RR */ - if (tcplen != tcph->doff*4) { - if (net_ratelimit()) - printk(KERN_ERR - "ipt_tcpmss_target: bad length (%d bytes)\n", - (*pskb)->len); - return NF_DROP; - } - - if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU) { - if (dst_mtu((*pskb)->dst) <= sizeof(struct iphdr) + - sizeof(struct tcphdr)) { - if (net_ratelimit()) - printk(KERN_ERR "ipt_tcpmss_target: " - "unknown or invalid path-MTU (%d)\n", - dst_mtu((*pskb)->dst)); - return NF_DROP; /* or IPT_CONTINUE ?? */ - } - - newmss = dst_mtu((*pskb)->dst) - sizeof(struct iphdr) - - sizeof(struct tcphdr); - } else - newmss = tcpmssinfo->mss; - - opt = (u_int8_t *)tcph; - for (i = sizeof(struct tcphdr); i < tcph->doff*4; i += optlen(opt, i)) { - if (opt[i] == TCPOPT_MSS && tcph->doff*4 - i >= TCPOLEN_MSS && - opt[i+1] == TCPOLEN_MSS) { - u_int16_t oldmss; - - oldmss = (opt[i+2] << 8) | opt[i+3]; - - if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU && - oldmss <= newmss) - return IPT_CONTINUE; - - opt[i+2] = (newmss & 0xff00) >> 8; - opt[i+3] = (newmss & 0x00ff); - - nf_proto_csum_replace2(&tcph->check, *pskb, - htons(oldmss), htons(newmss), 0); - return IPT_CONTINUE; - } - } - - /* - * MSS Option not found ?! add it.. - */ - if (skb_tailroom((*pskb)) < TCPOLEN_MSS) { - struct sk_buff *newskb; - - newskb = skb_copy_expand(*pskb, skb_headroom(*pskb), - TCPOLEN_MSS, GFP_ATOMIC); - if (!newskb) - return NF_DROP; - kfree_skb(*pskb); - *pskb = newskb; - iph = (*pskb)->nh.iph; - tcph = (void *)iph + iph->ihl*4; - } - - skb_put((*pskb), TCPOLEN_MSS); - - opt = (u_int8_t *)tcph + sizeof(struct tcphdr); - memmove(opt + TCPOLEN_MSS, opt, tcplen - sizeof(struct tcphdr)); - - nf_proto_csum_replace2(&tcph->check, *pskb, - htons(tcplen), htons(tcplen + TCPOLEN_MSS), 1); - opt[0] = TCPOPT_MSS; - opt[1] = TCPOLEN_MSS; - opt[2] = (newmss & 0xff00) >> 8; - opt[3] = (newmss & 0x00ff); - - nf_proto_csum_replace4(&tcph->check, *pskb, 0, *((__be32 *)opt), 0); - - oldval = ((__be16 *)tcph)[6]; - tcph->doff += TCPOLEN_MSS/4; - nf_proto_csum_replace2(&tcph->check, *pskb, - oldval, ((__be16 *)tcph)[6], 0); - - newtotlen = htons(ntohs(iph->tot_len) + TCPOLEN_MSS); - nf_csum_replace2(&iph->check, iph->tot_len, newtotlen); - iph->tot_len = newtotlen; - return IPT_CONTINUE; -} - -#define TH_SYN 0x02 - -static inline int find_syn_match(const struct ipt_entry_match *m) -{ - const struct ipt_tcp *tcpinfo = (const struct ipt_tcp *)m->data; - - if (strcmp(m->u.kernel.match->name, "tcp") == 0 && - tcpinfo->flg_cmp & TH_SYN && - !(tcpinfo->invflags & IPT_TCP_INV_FLAGS)) - return 1; - - return 0; -} - -/* Must specify -p tcp --syn/--tcp-flags SYN */ -static int -ipt_tcpmss_checkentry(const char *tablename, - const void *e_void, - const struct xt_target *target, - void *targinfo, - unsigned int hook_mask) -{ - const struct ipt_tcpmss_info *tcpmssinfo = targinfo; - const struct ipt_entry *e = e_void; - - if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU && - (hook_mask & ~((1 << NF_IP_FORWARD) | - (1 << NF_IP_LOCAL_OUT) | - (1 << NF_IP_POST_ROUTING))) != 0) { - printk("TCPMSS: path-MTU clamping only supported in " - "FORWARD, OUTPUT and POSTROUTING hooks\n"); - return 0; - } - - if (IPT_MATCH_ITERATE(e, find_syn_match)) - return 1; - printk("TCPMSS: Only works on TCP SYN packets\n"); - return 0; -} - -static struct ipt_target ipt_tcpmss_reg = { - .name = "TCPMSS", - .target = ipt_tcpmss_target, - .targetsize = sizeof(struct ipt_tcpmss_info), - .proto = IPPROTO_TCP, - .checkentry = ipt_tcpmss_checkentry, - .me = THIS_MODULE, -}; - -static int __init ipt_tcpmss_init(void) -{ - return ipt_register_target(&ipt_tcpmss_reg); -} - -static void __exit ipt_tcpmss_fini(void) -{ - ipt_unregister_target(&ipt_tcpmss_reg); -} - -module_init(ipt_tcpmss_init); -module_exit(ipt_tcpmss_fini); |