1d2912cb1SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only
2d33cbeebSPatrick McHardy /* FTP extension for TCP NAT alteration. */
3d33cbeebSPatrick McHardy
4d33cbeebSPatrick McHardy /* (C) 1999-2001 Paul `Rusty' Russell
5d33cbeebSPatrick McHardy * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
6d33cbeebSPatrick McHardy */
7d33cbeebSPatrick McHardy
85191d70fSArushi Singhal #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
95191d70fSArushi Singhal
10d33cbeebSPatrick McHardy #include <linux/module.h>
11d33cbeebSPatrick McHardy #include <linux/moduleparam.h>
12d33cbeebSPatrick McHardy #include <linux/inet.h>
13d33cbeebSPatrick McHardy #include <linux/tcp.h>
14d33cbeebSPatrick McHardy #include <linux/netfilter_ipv4.h>
15d33cbeebSPatrick McHardy #include <net/netfilter/nf_nat.h>
16d33cbeebSPatrick McHardy #include <net/netfilter/nf_nat_helper.h>
17d33cbeebSPatrick McHardy #include <net/netfilter/nf_conntrack_helper.h>
18d33cbeebSPatrick McHardy #include <net/netfilter/nf_conntrack_expect.h>
19d33cbeebSPatrick McHardy #include <linux/netfilter/nf_conntrack_ftp.h>
20d33cbeebSPatrick McHardy
2153b11308SFlavio Leitner #define NAT_HELPER_NAME "ftp"
2253b11308SFlavio Leitner
23d33cbeebSPatrick McHardy MODULE_LICENSE("GPL");
24d33cbeebSPatrick McHardy MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
25d33cbeebSPatrick McHardy MODULE_DESCRIPTION("ftp NAT helper");
2653b11308SFlavio Leitner MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
27d33cbeebSPatrick McHardy
28d33cbeebSPatrick McHardy /* FIXME: Time out? --RR */
29d33cbeebSPatrick McHardy
3053b11308SFlavio Leitner static struct nf_conntrack_nat_helper nat_helper_ftp =
3153b11308SFlavio Leitner NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
3253b11308SFlavio Leitner
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)33d33cbeebSPatrick McHardy static int nf_nat_ftp_fmt_cmd(struct nf_conn *ct, enum nf_ct_ftp_type type,
34d33cbeebSPatrick McHardy char *buffer, size_t buflen,
35d33cbeebSPatrick McHardy union nf_inet_addr *addr, u16 port)
36d33cbeebSPatrick McHardy {
37d33cbeebSPatrick McHardy switch (type) {
38d33cbeebSPatrick McHardy case NF_CT_FTP_PORT:
39d33cbeebSPatrick McHardy case NF_CT_FTP_PASV:
40d33cbeebSPatrick McHardy return snprintf(buffer, buflen, "%u,%u,%u,%u,%u,%u",
41d33cbeebSPatrick McHardy ((unsigned char *)&addr->ip)[0],
42d33cbeebSPatrick McHardy ((unsigned char *)&addr->ip)[1],
43d33cbeebSPatrick McHardy ((unsigned char *)&addr->ip)[2],
44d33cbeebSPatrick McHardy ((unsigned char *)&addr->ip)[3],
45d33cbeebSPatrick McHardy port >> 8,
46d33cbeebSPatrick McHardy port & 0xFF);
47d33cbeebSPatrick McHardy case NF_CT_FTP_EPRT:
48d33cbeebSPatrick McHardy if (nf_ct_l3num(ct) == NFPROTO_IPV4)
49d33cbeebSPatrick McHardy return snprintf(buffer, buflen, "|1|%pI4|%u|",
50d33cbeebSPatrick McHardy &addr->ip, port);
51d33cbeebSPatrick McHardy else
52d33cbeebSPatrick McHardy return snprintf(buffer, buflen, "|2|%pI6|%u|",
53d33cbeebSPatrick McHardy &addr->ip6, port);
54d33cbeebSPatrick McHardy case NF_CT_FTP_EPSV:
55d33cbeebSPatrick McHardy return snprintf(buffer, buflen, "|||%u|", port);
56d33cbeebSPatrick McHardy }
57d33cbeebSPatrick McHardy
58d33cbeebSPatrick McHardy return 0;
59d33cbeebSPatrick McHardy }
60d33cbeebSPatrick McHardy
61d33cbeebSPatrick McHardy /* So, this packet has hit the connection tracking matching code.
62d33cbeebSPatrick McHardy Mangle it, and change the expectation to match the new version. */
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)63d33cbeebSPatrick McHardy static unsigned int nf_nat_ftp(struct sk_buff *skb,
64d33cbeebSPatrick McHardy enum ip_conntrack_info ctinfo,
65d33cbeebSPatrick McHardy enum nf_ct_ftp_type type,
66d33cbeebSPatrick McHardy unsigned int protoff,
67d33cbeebSPatrick McHardy unsigned int matchoff,
68d33cbeebSPatrick McHardy unsigned int matchlen,
69d33cbeebSPatrick McHardy struct nf_conntrack_expect *exp)
70d33cbeebSPatrick McHardy {
71d33cbeebSPatrick McHardy union nf_inet_addr newaddr;
72d33cbeebSPatrick McHardy u_int16_t port;
73d33cbeebSPatrick McHardy int dir = CTINFO2DIR(ctinfo);
74d33cbeebSPatrick McHardy struct nf_conn *ct = exp->master;
75d33cbeebSPatrick McHardy char buffer[sizeof("|1||65535|") + INET6_ADDRSTRLEN];
76d33cbeebSPatrick McHardy unsigned int buflen;
77d33cbeebSPatrick McHardy
785191d70fSArushi Singhal pr_debug("type %i, off %u len %u\n", type, matchoff, matchlen);
79d33cbeebSPatrick McHardy
80d33cbeebSPatrick McHardy /* Connection will come from wherever this packet goes, hence !dir */
81d33cbeebSPatrick McHardy newaddr = ct->tuplehash[!dir].tuple.dst.u3;
82d33cbeebSPatrick McHardy exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
83d33cbeebSPatrick McHardy exp->dir = !dir;
84d33cbeebSPatrick McHardy
85d33cbeebSPatrick McHardy /* When you see the packet, we need to NAT it the same as the
86d33cbeebSPatrick McHardy * this one. */
87d33cbeebSPatrick McHardy exp->expectfn = nf_nat_follow_master;
88d33cbeebSPatrick McHardy
89*c92c2717SFlorian Westphal port = nf_nat_exp_find_port(exp, ntohs(exp->saved_proto.tcp.port));
90b20ab9ccSPablo Neira Ayuso if (port == 0) {
91*c92c2717SFlorian Westphal nf_ct_helper_log(skb, exp->master, "all ports in use");
92d33cbeebSPatrick McHardy return NF_DROP;
93b20ab9ccSPablo Neira Ayuso }
94d33cbeebSPatrick McHardy
95d33cbeebSPatrick McHardy buflen = nf_nat_ftp_fmt_cmd(ct, type, buffer, sizeof(buffer),
96d33cbeebSPatrick McHardy &newaddr, port);
97d33cbeebSPatrick McHardy if (!buflen)
98d33cbeebSPatrick McHardy goto out;
99d33cbeebSPatrick McHardy
100d33cbeebSPatrick McHardy pr_debug("calling nf_nat_mangle_tcp_packet\n");
101d33cbeebSPatrick McHardy
102d33cbeebSPatrick McHardy if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
103d33cbeebSPatrick McHardy matchlen, buffer, buflen))
104d33cbeebSPatrick McHardy goto out;
105d33cbeebSPatrick McHardy
106d33cbeebSPatrick McHardy return NF_ACCEPT;
107d33cbeebSPatrick McHardy
108d33cbeebSPatrick McHardy out:
109b20ab9ccSPablo Neira Ayuso nf_ct_helper_log(skb, ct, "cannot mangle packet");
110d33cbeebSPatrick McHardy nf_ct_unexpect_related(exp);
111d33cbeebSPatrick McHardy return NF_DROP;
112d33cbeebSPatrick McHardy }
113d33cbeebSPatrick McHardy
nf_nat_ftp_fini(void)114d33cbeebSPatrick McHardy static void __exit nf_nat_ftp_fini(void)
115d33cbeebSPatrick McHardy {
11653b11308SFlavio Leitner nf_nat_helper_unregister(&nat_helper_ftp);
117d33cbeebSPatrick McHardy RCU_INIT_POINTER(nf_nat_ftp_hook, NULL);
118d33cbeebSPatrick McHardy synchronize_rcu();
119d33cbeebSPatrick McHardy }
120d33cbeebSPatrick McHardy
nf_nat_ftp_init(void)121d33cbeebSPatrick McHardy static int __init nf_nat_ftp_init(void)
122d33cbeebSPatrick McHardy {
123d33cbeebSPatrick McHardy BUG_ON(nf_nat_ftp_hook != NULL);
12453b11308SFlavio Leitner nf_nat_helper_register(&nat_helper_ftp);
125d33cbeebSPatrick McHardy RCU_INIT_POINTER(nf_nat_ftp_hook, nf_nat_ftp);
126d33cbeebSPatrick McHardy return 0;
127d33cbeebSPatrick McHardy }
128d33cbeebSPatrick McHardy
129d33cbeebSPatrick McHardy /* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
warn_set(const char * val,const struct kernel_param * kp)130e4dca7b7SKees Cook static int warn_set(const char *val, const struct kernel_param *kp)
131d33cbeebSPatrick McHardy {
1325191d70fSArushi Singhal pr_info("kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
133d33cbeebSPatrick McHardy return 0;
134d33cbeebSPatrick McHardy }
135d33cbeebSPatrick McHardy module_param_call(ports, warn_set, NULL, NULL, 0);
136d33cbeebSPatrick McHardy
137d33cbeebSPatrick McHardy module_init(nf_nat_ftp_init);
138d33cbeebSPatrick McHardy module_exit(nf_nat_ftp_fini);
139