1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* IRC extension for IP connection tracking, Version 1.21
3 * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org>
4 * based on RR's ip_conntrack_ftp.c
5 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 #include <linux/module.h>
11 #include <linux/moduleparam.h>
12 #include <linux/skbuff.h>
15 #include <linux/tcp.h>
16 #include <linux/netfilter.h>
17 #include <linux/slab.h>
19 #include <net/netfilter/nf_conntrack.h>
20 #include <net/netfilter/nf_conntrack_expect.h>
21 #include <net/netfilter/nf_conntrack_helper.h>
22 #include <linux/netfilter/nf_conntrack_irc.h>
25 static unsigned short ports[MAX_PORTS];
26 static unsigned int ports_c;
27 static unsigned int max_dcc_channels = 8;
28 static unsigned int dcc_timeout __read_mostly = 300;
29 /* This is slow, but it's simple. --RR */
30 static char *irc_buffer;
31 static DEFINE_SPINLOCK(irc_buffer_lock);
33 unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
34 enum ip_conntrack_info ctinfo,
36 unsigned int matchoff,
37 unsigned int matchlen,
38 struct nf_conntrack_expect *exp) __read_mostly;
39 EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
41 #define HELPER_NAME "irc"
43 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
44 MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
45 MODULE_LICENSE("GPL");
46 MODULE_ALIAS("ip_conntrack_irc");
47 MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
49 module_param_array(ports, ushort, &ports_c, 0400);
50 MODULE_PARM_DESC(ports, "port numbers of IRC servers");
51 module_param(max_dcc_channels, uint, 0400);
52 MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
54 module_param(dcc_timeout, uint, 0400);
55 MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
57 static const char *const dccprotos[] = {
58 "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
63 /* tries to get the ip_addr and port out of a dcc command
64 * return value: -1 on failure, 0 on success
65 * data pointer to first byte of DCC command data
66 * data_end pointer to last byte of dcc command data
67 * ip returns parsed ip of dcc command
68 * port returns parsed port of dcc command
69 * ad_beg_p returns pointer to first byte of addr data
70 * ad_end_p returns pointer to last byte of addr data
72 static int parse_dcc(char *data, const char *data_end, __be32 *ip,
73 u_int16_t *port, char **ad_beg_p, char **ad_end_p)
77 /* at least 12: "AAAAAAAA P\1\n" */
78 while (*data++ != ' ')
79 if (data > data_end - 12)
82 /* Make sure we have a newline character within the packet boundaries
83 * because simple_strtoul parses until the first invalid character. */
84 for (tmp = data; tmp <= data_end; tmp++)
87 if (tmp > data_end || *tmp != '\n')
91 *ip = cpu_to_be32(simple_strtoul(data, &data, 10));
93 /* skip blanks between ip and port */
94 while (*data == ' ') {
100 *port = simple_strtoul(data, &data, 10);
106 static int help(struct sk_buff *skb, unsigned int protoff,
107 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
109 unsigned int dataoff;
110 const struct iphdr *iph;
111 const struct tcphdr *th;
113 const char *data_limit;
115 int dir = CTINFO2DIR(ctinfo);
116 struct nf_conntrack_expect *exp;
117 struct nf_conntrack_tuple *tuple;
121 int i, ret = NF_ACCEPT;
122 char *addr_beg_p, *addr_end_p;
123 typeof(nf_nat_irc_hook) nf_nat_irc;
125 /* If packet is coming from IRC server */
126 if (dir == IP_CT_DIR_REPLY)
129 /* Until there's been traffic both ways, don't look in packets. */
130 if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
133 /* Not a full tcp header? */
134 th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
139 dataoff = protoff + th->doff*4;
140 if (dataoff >= skb->len)
143 spin_lock_bh(&irc_buffer_lock);
144 ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
146 BUG_ON(ib_ptr == NULL);
149 data_limit = ib_ptr + skb->len - dataoff;
151 /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
152 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
153 while (data < data_limit - (19 + MINMATCHLEN)) {
154 if (memcmp(data, "\1DCC ", 5)) {
159 /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
162 pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
163 &iph->saddr, ntohs(th->source),
164 &iph->daddr, ntohs(th->dest));
166 for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
167 if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
171 data += strlen(dccprotos[i]);
172 pr_debug("DCC %s detected\n", dccprotos[i]);
175 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
176 * data left (== 14/13 bytes) */
177 if (parse_dcc(data, data_limit, &dcc_ip,
178 &dcc_port, &addr_beg_p, &addr_end_p)) {
179 pr_debug("unable to parse dcc command\n");
183 pr_debug("DCC bound ip/port: %pI4:%u\n",
186 /* dcc_ip can be the internal OR external (NAT'ed) IP */
187 tuple = &ct->tuplehash[dir].tuple;
188 if (tuple->src.u3.ip != dcc_ip &&
189 tuple->dst.u3.ip != dcc_ip) {
190 net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n",
196 exp = nf_ct_expect_alloc(ct);
198 nf_ct_helper_log(skb, ct,
199 "cannot alloc expectation");
203 tuple = &ct->tuplehash[!dir].tuple;
204 port = htons(dcc_port);
205 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
207 NULL, &tuple->dst.u3,
208 IPPROTO_TCP, NULL, &port);
210 nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
211 if (nf_nat_irc && ct->status & IPS_NAT_MASK)
212 ret = nf_nat_irc(skb, ctinfo, protoff,
214 addr_end_p - addr_beg_p,
216 else if (nf_ct_expect_related(exp, 0) != 0) {
217 nf_ct_helper_log(skb, ct,
218 "cannot add expectation");
221 nf_ct_expect_put(exp);
226 spin_unlock_bh(&irc_buffer_lock);
230 static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
231 static struct nf_conntrack_expect_policy irc_exp_policy;
233 static int __init nf_conntrack_irc_init(void)
237 if (max_dcc_channels < 1) {
238 pr_err("max_dcc_channels must not be zero\n");
242 if (max_dcc_channels > NF_CT_EXPECT_MAX_CNT) {
243 pr_err("max_dcc_channels must not be more than %u\n",
244 NF_CT_EXPECT_MAX_CNT);
248 irc_exp_policy.max_expected = max_dcc_channels;
249 irc_exp_policy.timeout = dcc_timeout;
251 irc_buffer = kmalloc(65536, GFP_KERNEL);
255 /* If no port given, default to standard irc port */
257 ports[ports_c++] = IRC_PORT;
259 for (i = 0; i < ports_c; i++) {
260 nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, HELPER_NAME,
261 IRC_PORT, ports[i], i, &irc_exp_policy,
262 0, help, NULL, THIS_MODULE);
265 ret = nf_conntrack_helpers_register(&irc[0], ports_c);
267 pr_err("failed to register helpers\n");
275 static void __exit nf_conntrack_irc_fini(void)
277 nf_conntrack_helpers_unregister(irc, ports_c);
281 module_init(nf_conntrack_irc_init);
282 module_exit(nf_conntrack_irc_fini);