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Release 4.8 net/netfilter/nf_nat_ftp.c

Directory: net/netfilter
/* FTP extension for TCP NAT alteration. */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <>
 * 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/moduleparam.h>
#include <linux/inet.h>
#include <linux/tcp.h>
#include <linux/netfilter_ipv4.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_ftp.h>

MODULE_AUTHOR("Rusty Russell <>");

/* FIXME: Time out? --RR */

static int nf_nat_ftp_fmt_cmd(struct nf_conn *ct, enum nf_ct_ftp_type type, char *buffer, size_t buflen, union nf_inet_addr *addr, u16 port) { switch (type) { case NF_CT_FTP_PORT: case NF_CT_FTP_PASV: return snprintf(buffer, buflen, "%u,%u,%u,%u,%u,%u", ((unsigned char *)&addr->ip)[0], ((unsigned char *)&addr->ip)[1], ((unsigned char *)&addr->ip)[2], ((unsigned char *)&addr->ip)[3], port >> 8, port & 0xFF); case NF_CT_FTP_EPRT: if (nf_ct_l3num(ct) == NFPROTO_IPV4) return snprintf(buffer, buflen, "|1|%pI4|%u|", &addr->ip, port); else return snprintf(buffer, buflen, "|2|%pI6|%u|", &addr->ip6, port); case NF_CT_FTP_EPSV: return snprintf(buffer, buflen, "|||%u|", port); } return 0; }


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/* So, this packet has hit the connection tracking matching code. Mangle it, and change the expectation to match the new version. */
static unsigned int nf_nat_ftp(struct sk_buff *skb, enum ip_conntrack_info ctinfo, enum nf_ct_ftp_type type, unsigned int protoff, unsigned int matchoff, unsigned int matchlen, struct nf_conntrack_expect *exp) { union nf_inet_addr newaddr; u_int16_t port; int dir = CTINFO2DIR(ctinfo); struct nf_conn *ct = exp->master; char buffer[sizeof("|1||65535|") + INET6_ADDRSTRLEN]; unsigned int buflen; pr_debug("FTP_NAT: type %i, off %u len %u\n", type, matchoff, matchlen); /* Connection will come from wherever this packet goes, hence !dir */ newaddr = ct->tuplehash[!dir].tuple.dst.u3; exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; exp->dir = !dir; /* When you see the packet, we need to NAT it the same as the * this one. */ exp->expectfn = nf_nat_follow_master; /* Try to get same port: if not, try to change it. */ for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) { int ret; exp->tuple.dst.u.tcp.port = htons(port); ret = nf_ct_expect_related(exp); if (ret == 0) break; else if (ret != -EBUSY) { port = 0; break; } } if (port == 0) { nf_ct_helper_log(skb, ct, "all ports in use"); return NF_DROP; } buflen = nf_nat_ftp_fmt_cmd(ct, type, buffer, sizeof(buffer), &newaddr, port); if (!buflen) goto out; pr_debug("calling nf_nat_mangle_tcp_packet\n"); if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff, matchlen, buffer, buflen)) goto out; return NF_ACCEPT; out: nf_ct_helper_log(skb, ct, "cannot mangle packet"); nf_ct_unexpect_related(exp); return NF_DROP; }


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patrick mchardypatrick mchardy206.39%444.44%
herbert xuherbert xu20.64%111.11%

static void __exit nf_nat_ftp_fini(void) { RCU_INIT_POINTER(nf_nat_ftp_hook, NULL); synchronize_rcu(); }


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static int __init nf_nat_ftp_init(void) { BUG_ON(nf_nat_ftp_hook != NULL); RCU_INIT_POINTER(nf_nat_ftp_hook, nf_nat_ftp); return 0; }


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stephen hemmingerstephen hemminger13.85%133.33%

/* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
static int warn_set(const char *val, struct kernel_param *kp) { printk(KERN_INFO KBUILD_MODNAME ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n"); return 0; }


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module_param_call(ports, warn_set, NULL, NULL, 0); module_init(nf_nat_ftp_init); module_exit(nf_nat_ftp_fini);

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pablo neira ayusopablo neira ayuso446.81%218.18%
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herbert xuherbert xu20.31%19.09%
Directory: net/netfilter
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