cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ipt_SYNPROXY.c (3111B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (c) 2013 Patrick McHardy <kaber@trash.net>
      4 */
      5
      6#include <linux/netfilter_ipv4/ip_tables.h>
      7#include <linux/netfilter/x_tables.h>
      8#include <linux/netfilter/xt_SYNPROXY.h>
      9
     10#include <net/netfilter/nf_synproxy.h>
     11
     12static unsigned int
     13synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par)
     14{
     15	const struct xt_synproxy_info *info = par->targinfo;
     16	struct net *net = xt_net(par);
     17	struct synproxy_net *snet = synproxy_pernet(net);
     18	struct synproxy_options opts = {};
     19	struct tcphdr *th, _th;
     20
     21	if (nf_ip_checksum(skb, xt_hooknum(par), par->thoff, IPPROTO_TCP))
     22		return NF_DROP;
     23
     24	th = skb_header_pointer(skb, par->thoff, sizeof(_th), &_th);
     25	if (th == NULL)
     26		return NF_DROP;
     27
     28	if (!synproxy_parse_options(skb, par->thoff, th, &opts))
     29		return NF_DROP;
     30
     31	if (th->syn && !(th->ack || th->fin || th->rst)) {
     32		/* Initial SYN from client */
     33		this_cpu_inc(snet->stats->syn_received);
     34
     35		if (th->ece && th->cwr)
     36			opts.options |= XT_SYNPROXY_OPT_ECN;
     37
     38		opts.options &= info->options;
     39		opts.mss_encode = opts.mss_option;
     40		opts.mss_option = info->mss;
     41		if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP)
     42			synproxy_init_timestamp_cookie(info, &opts);
     43		else
     44			opts.options &= ~(XT_SYNPROXY_OPT_WSCALE |
     45					  XT_SYNPROXY_OPT_SACK_PERM |
     46					  XT_SYNPROXY_OPT_ECN);
     47
     48		synproxy_send_client_synack(net, skb, th, &opts);
     49		consume_skb(skb);
     50		return NF_STOLEN;
     51	} else if (th->ack && !(th->fin || th->rst || th->syn)) {
     52		/* ACK from client */
     53		if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq))) {
     54			consume_skb(skb);
     55			return NF_STOLEN;
     56		} else {
     57			return NF_DROP;
     58		}
     59	}
     60
     61	return XT_CONTINUE;
     62}
     63
     64static int synproxy_tg4_check(const struct xt_tgchk_param *par)
     65{
     66	struct synproxy_net *snet = synproxy_pernet(par->net);
     67	const struct ipt_entry *e = par->entryinfo;
     68	int err;
     69
     70	if (e->ip.proto != IPPROTO_TCP ||
     71	    e->ip.invflags & XT_INV_PROTO)
     72		return -EINVAL;
     73
     74	err = nf_ct_netns_get(par->net, par->family);
     75	if (err)
     76		return err;
     77
     78	err = nf_synproxy_ipv4_init(snet, par->net);
     79	if (err) {
     80		nf_ct_netns_put(par->net, par->family);
     81		return err;
     82	}
     83
     84	return err;
     85}
     86
     87static void synproxy_tg4_destroy(const struct xt_tgdtor_param *par)
     88{
     89	struct synproxy_net *snet = synproxy_pernet(par->net);
     90
     91	nf_synproxy_ipv4_fini(snet, par->net);
     92	nf_ct_netns_put(par->net, par->family);
     93}
     94
     95static struct xt_target synproxy_tg4_reg __read_mostly = {
     96	.name		= "SYNPROXY",
     97	.family		= NFPROTO_IPV4,
     98	.hooks		= (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD),
     99	.target		= synproxy_tg4,
    100	.targetsize	= sizeof(struct xt_synproxy_info),
    101	.checkentry	= synproxy_tg4_check,
    102	.destroy	= synproxy_tg4_destroy,
    103	.me		= THIS_MODULE,
    104};
    105
    106static int __init synproxy_tg4_init(void)
    107{
    108	return xt_register_target(&synproxy_tg4_reg);
    109}
    110
    111static void __exit synproxy_tg4_exit(void)
    112{
    113	xt_unregister_target(&synproxy_tg4_reg);
    114}
    115
    116module_init(synproxy_tg4_init);
    117module_exit(synproxy_tg4_exit);
    118
    119MODULE_LICENSE("GPL");
    120MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
    121MODULE_DESCRIPTION("Intercept TCP connections and establish them using syncookies");