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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nf_nat_irc.c (3493B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/* IRC extension for TCP NAT alteration.
      3 *
      4 * (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
      5 * (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
      6 * based on a copy of RR's ip_nat_ftp.c
      7 */
      8
      9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
     10
     11#include <linux/module.h>
     12#include <linux/moduleparam.h>
     13#include <linux/tcp.h>
     14#include <linux/kernel.h>
     15
     16#include <net/netfilter/nf_nat.h>
     17#include <net/netfilter/nf_nat_helper.h>
     18#include <net/netfilter/nf_conntrack_helper.h>
     19#include <net/netfilter/nf_conntrack_expect.h>
     20#include <linux/netfilter/nf_conntrack_irc.h>
     21
     22#define NAT_HELPER_NAME "irc"
     23
     24MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
     25MODULE_DESCRIPTION("IRC (DCC) NAT helper");
     26MODULE_LICENSE("GPL");
     27MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
     28
     29static struct nf_conntrack_nat_helper nat_helper_irc =
     30	NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
     31
     32static unsigned int help(struct sk_buff *skb,
     33			 enum ip_conntrack_info ctinfo,
     34			 unsigned int protoff,
     35			 unsigned int matchoff,
     36			 unsigned int matchlen,
     37			 struct nf_conntrack_expect *exp)
     38{
     39	char buffer[sizeof("4294967296 65635")];
     40	struct nf_conn *ct = exp->master;
     41	union nf_inet_addr newaddr;
     42	u_int16_t port;
     43
     44	/* Reply comes from server. */
     45	newaddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3;
     46
     47	exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
     48	exp->dir = IP_CT_DIR_REPLY;
     49	exp->expectfn = nf_nat_follow_master;
     50
     51	/* Try to get same port: if not, try to change it. */
     52	for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
     53		int ret;
     54
     55		exp->tuple.dst.u.tcp.port = htons(port);
     56		ret = nf_ct_expect_related(exp, 0);
     57		if (ret == 0)
     58			break;
     59		else if (ret != -EBUSY) {
     60			port = 0;
     61			break;
     62		}
     63	}
     64
     65	if (port == 0) {
     66		nf_ct_helper_log(skb, ct, "all ports in use");
     67		return NF_DROP;
     68	}
     69
     70	/* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27
     71	 * strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28
     72	 * strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26
     73	 * strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26
     74	 * strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27
     75	 *
     76	 * AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits,
     77	 *                        255.255.255.255==4294967296, 10 digits)
     78	 * P:         bound port (min 1 d, max 5d (65635))
     79	 * F:         filename   (min 1 d )
     80	 * S:         size       (min 1 d )
     81	 * 0x01, \n:  terminators
     82	 */
     83	/* AAA = "us", ie. where server normally talks to. */
     84	snprintf(buffer, sizeof(buffer), "%u %u", ntohl(newaddr.ip), port);
     85	pr_debug("inserting '%s' == %pI4, port %u\n",
     86		 buffer, &newaddr.ip, port);
     87
     88	if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
     89				      matchlen, buffer, strlen(buffer))) {
     90		nf_ct_helper_log(skb, ct, "cannot mangle packet");
     91		nf_ct_unexpect_related(exp);
     92		return NF_DROP;
     93	}
     94
     95	return NF_ACCEPT;
     96}
     97
     98static void __exit nf_nat_irc_fini(void)
     99{
    100	nf_nat_helper_unregister(&nat_helper_irc);
    101	RCU_INIT_POINTER(nf_nat_irc_hook, NULL);
    102	synchronize_rcu();
    103}
    104
    105static int __init nf_nat_irc_init(void)
    106{
    107	BUG_ON(nf_nat_irc_hook != NULL);
    108	nf_nat_helper_register(&nat_helper_irc);
    109	RCU_INIT_POINTER(nf_nat_irc_hook, help);
    110	return 0;
    111}
    112
    113/* Prior to 2.6.11, we had a ports param.  No longer, but don't break users. */
    114static int warn_set(const char *val, const struct kernel_param *kp)
    115{
    116	pr_info("kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
    117	return 0;
    118}
    119module_param_call(ports, warn_set, NULL, NULL, 0);
    120
    121module_init(nf_nat_irc_init);
    122module_exit(nf_nat_irc_fini);