Release 4.14 net/netfilter/xt_tcpmss.c
/* Kernel module to match TCP MSS values. */
/* Copyright (C) 2000 Marc Boucher <marc@mbsi.ca>
* Portions (C) 2005 by Harald Welte <laforge@netfilter.org>
*
* 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 <net/tcp.h>
#include <linux/netfilter/xt_tcpmss.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
MODULE_DESCRIPTION("Xtables: TCP MSS match");
MODULE_ALIAS("ipt_tcpmss");
MODULE_ALIAS("ip6t_tcpmss");
static bool
tcpmss_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_tcpmss_match_info *info = par->matchinfo;
const struct tcphdr *th;
struct tcphdr _tcph;
/* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
const u_int8_t *op;
u8 _opt[15 * 4 - sizeof(_tcph)];
unsigned int i, optlen;
/* If we don't have the whole header, drop packet. */
th = skb_header_pointer(skb, par->thoff, sizeof(_tcph), &_tcph);
if (th == NULL)
goto dropit;
/* Malformed. */
if (th->doff*4 < sizeof(*th))
goto dropit;
optlen = th->doff*4 - sizeof(*th);
if (!optlen)
goto out;
/* Truncated options. */
op = skb_header_pointer(skb, par->thoff + sizeof(*th), optlen, _opt);
if (op == NULL)
goto dropit;
for (i = 0; i < optlen; ) {
if (op[i] == TCPOPT_MSS
&& (optlen - i) >= TCPOLEN_MSS
&& op[i+1] == TCPOLEN_MSS) {
u_int16_t mssval;
mssval = (op[i+2] << 8) | op[i+3];
return (mssval >= info->mss_min &&
mssval <= info->mss_max) ^ info->invert;
}
if (op[i] < 2)
i++;
else
i += op[i+1] ? : 1;
}
out:
return info->invert;
dropit:
par->hotdrop = true;
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 111 | 38.54% | 1 | 10.00% |
| Rusty Russell | 78 | 27.08% | 1 | 10.00% |
| David S. Miller | 53 | 18.40% | 1 | 10.00% |
| Jan Engelhardt | 26 | 9.03% | 6 | 60.00% |
| Patrick McHardy | 20 | 6.94% | 1 | 10.00% |
| Total | 288 | 100.00% | 10 | 100.00% |
static struct xt_match tcpmss_mt_reg[] __read_mostly = {
{
.name = "tcpmss",
.family = NFPROTO_IPV4,
.match = tcpmss_mt,
.matchsize = sizeof(struct xt_tcpmss_match_info),
.proto = IPPROTO_TCP,
.me = THIS_MODULE,
},
{
.name = "tcpmss",
.family = NFPROTO_IPV6,
.match = tcpmss_mt,
.matchsize = sizeof(struct xt_tcpmss_match_info),
.proto = IPPROTO_TCP,
.me = THIS_MODULE,
},
};
static int __init tcpmss_mt_init(void)
{
return xt_register_matches(tcpmss_mt_reg, ARRAY_SIZE(tcpmss_mt_reg));
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 12 | 60.00% | 1 | 25.00% |
| Patrick McHardy | 4 | 20.00% | 1 | 25.00% |
| Jan Engelhardt | 3 | 15.00% | 1 | 25.00% |
| Harald Welte | 1 | 5.00% | 1 | 25.00% |
| Total | 20 | 100.00% | 4 | 100.00% |
static void __exit tcpmss_mt_exit(void)
{
xt_unregister_matches(tcpmss_mt_reg, ARRAY_SIZE(tcpmss_mt_reg));
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 11 | 57.89% | 1 | 25.00% |
| Patrick McHardy | 4 | 21.05% | 1 | 25.00% |
| Jan Engelhardt | 3 | 15.79% | 1 | 25.00% |
| Harald Welte | 1 | 5.26% | 1 | 25.00% |
| Total | 19 | 100.00% | 4 | 100.00% |
module_init(tcpmss_mt_init);
module_exit(tcpmss_mt_exit);
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 166 | 35.62% | 1 | 5.26% |
| Rusty Russell | 78 | 16.74% | 1 | 5.26% |
| Patrick McHardy | 64 | 13.73% | 4 | 21.05% |
| David S. Miller | 53 | 11.37% | 1 | 5.26% |
| Harald Welte | 49 | 10.52% | 2 | 10.53% |
| Jan Engelhardt | 45 | 9.66% | 9 | 47.37% |
| Art Haas | 11 | 2.36% | 1 | 5.26% |
| Total | 466 | 100.00% | 19 | 100.00% |
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