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_ftp.c (4127B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/* FTP extension for TCP NAT alteration. */
      3
      4/* (C) 1999-2001 Paul `Rusty' Russell
      5 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
      6 */
      7
      8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      9
     10#include <linux/module.h>
     11#include <linux/moduleparam.h>
     12#include <linux/inet.h>
     13#include <linux/tcp.h>
     14#include <linux/netfilter_ipv4.h>
     15#include <net/netfilter/nf_nat.h>
     16#include <net/netfilter/nf_nat_helper.h>
     17#include <net/netfilter/nf_conntrack_helper.h>
     18#include <net/netfilter/nf_conntrack_expect.h>
     19#include <linux/netfilter/nf_conntrack_ftp.h>
     20
     21#define NAT_HELPER_NAME "ftp"
     22
     23MODULE_LICENSE("GPL");
     24MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
     25MODULE_DESCRIPTION("ftp NAT helper");
     26MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
     27
     28/* FIXME: Time out? --RR */
     29
     30static struct nf_conntrack_nat_helper nat_helper_ftp =
     31	NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
     32
     33static int nf_nat_ftp_fmt_cmd(struct nf_conn *ct, enum nf_ct_ftp_type type,
     34			      char *buffer, size_t buflen,
     35			      union nf_inet_addr *addr, u16 port)
     36{
     37	switch (type) {
     38	case NF_CT_FTP_PORT:
     39	case NF_CT_FTP_PASV:
     40		return snprintf(buffer, buflen, "%u,%u,%u,%u,%u,%u",
     41				((unsigned char *)&addr->ip)[0],
     42				((unsigned char *)&addr->ip)[1],
     43				((unsigned char *)&addr->ip)[2],
     44				((unsigned char *)&addr->ip)[3],
     45				port >> 8,
     46				port & 0xFF);
     47	case NF_CT_FTP_EPRT:
     48		if (nf_ct_l3num(ct) == NFPROTO_IPV4)
     49			return snprintf(buffer, buflen, "|1|%pI4|%u|",
     50					&addr->ip, port);
     51		else
     52			return snprintf(buffer, buflen, "|2|%pI6|%u|",
     53					&addr->ip6, port);
     54	case NF_CT_FTP_EPSV:
     55		return snprintf(buffer, buflen, "|||%u|", port);
     56	}
     57
     58	return 0;
     59}
     60
     61/* So, this packet has hit the connection tracking matching code.
     62   Mangle it, and change the expectation to match the new version. */
     63static unsigned int nf_nat_ftp(struct sk_buff *skb,
     64			       enum ip_conntrack_info ctinfo,
     65			       enum nf_ct_ftp_type type,
     66			       unsigned int protoff,
     67			       unsigned int matchoff,
     68			       unsigned int matchlen,
     69			       struct nf_conntrack_expect *exp)
     70{
     71	union nf_inet_addr newaddr;
     72	u_int16_t port;
     73	int dir = CTINFO2DIR(ctinfo);
     74	struct nf_conn *ct = exp->master;
     75	char buffer[sizeof("|1||65535|") + INET6_ADDRSTRLEN];
     76	unsigned int buflen;
     77
     78	pr_debug("type %i, off %u len %u\n", type, matchoff, matchlen);
     79
     80	/* Connection will come from wherever this packet goes, hence !dir */
     81	newaddr = ct->tuplehash[!dir].tuple.dst.u3;
     82	exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
     83	exp->dir = !dir;
     84
     85	/* When you see the packet, we need to NAT it the same as the
     86	 * this one. */
     87	exp->expectfn = nf_nat_follow_master;
     88
     89	/* Try to get same port: if not, try to change it. */
     90	for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
     91		int ret;
     92
     93		exp->tuple.dst.u.tcp.port = htons(port);
     94		ret = nf_ct_expect_related(exp, 0);
     95		if (ret == 0)
     96			break;
     97		else if (ret != -EBUSY) {
     98			port = 0;
     99			break;
    100		}
    101	}
    102
    103	if (port == 0) {
    104		nf_ct_helper_log(skb, ct, "all ports in use");
    105		return NF_DROP;
    106	}
    107
    108	buflen = nf_nat_ftp_fmt_cmd(ct, type, buffer, sizeof(buffer),
    109				    &newaddr, port);
    110	if (!buflen)
    111		goto out;
    112
    113	pr_debug("calling nf_nat_mangle_tcp_packet\n");
    114
    115	if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
    116				      matchlen, buffer, buflen))
    117		goto out;
    118
    119	return NF_ACCEPT;
    120
    121out:
    122	nf_ct_helper_log(skb, ct, "cannot mangle packet");
    123	nf_ct_unexpect_related(exp);
    124	return NF_DROP;
    125}
    126
    127static void __exit nf_nat_ftp_fini(void)
    128{
    129	nf_nat_helper_unregister(&nat_helper_ftp);
    130	RCU_INIT_POINTER(nf_nat_ftp_hook, NULL);
    131	synchronize_rcu();
    132}
    133
    134static int __init nf_nat_ftp_init(void)
    135{
    136	BUG_ON(nf_nat_ftp_hook != NULL);
    137	nf_nat_helper_register(&nat_helper_ftp);
    138	RCU_INIT_POINTER(nf_nat_ftp_hook, nf_nat_ftp);
    139	return 0;
    140}
    141
    142/* Prior to 2.6.11, we had a ports param.  No longer, but don't break users. */
    143static int warn_set(const char *val, const struct kernel_param *kp)
    144{
    145	pr_info("kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
    146	return 0;
    147}
    148module_param_call(ports, warn_set, NULL, NULL, 0);
    149
    150module_init(nf_nat_ftp_init);
    151module_exit(nf_nat_ftp_fini);