[ATM]: [adummy] dummy ATM driver (similar to net/dummy)
[deliverable/linux.git] / net / ipv4 / netfilter / ip_conntrack_irc.c
CommitLineData
1da177e4
LT
1/* IRC extension for IP connection tracking, Version 1.21
2 * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org>
3 * based on RR's ip_conntrack_ftp.c
4 *
5 * ip_conntrack_irc.c,v 1.21 2002/02/05 14:49:26 laforge Exp
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 **
12 * Module load syntax:
13 * insmod ip_conntrack_irc.o ports=port1,port2,...port<MAX_PORTS>
14 * max_dcc_channels=n dcc_timeout=secs
15 *
16 * please give the ports of all IRC servers You wish to connect to.
17 * If You don't specify ports, the default will be port 6667.
18 * With max_dcc_channels you can define the maximum number of not
19 * yet answered DCC channels per IRC session (default 8).
20 * With dcc_timeout you can specify how long the system waits for
21 * an expected DCC channel (default 300 seconds).
22 *
23 */
24
25#include <linux/config.h>
26#include <linux/module.h>
27#include <linux/netfilter.h>
28#include <linux/ip.h>
29#include <net/checksum.h>
30#include <net/tcp.h>
31
1da177e4
LT
32#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
33#include <linux/netfilter_ipv4/ip_conntrack_irc.h>
34#include <linux/moduleparam.h>
35
36#define MAX_PORTS 8
2fce76af 37static unsigned short ports[MAX_PORTS];
1da177e4
LT
38static int ports_c;
39static int max_dcc_channels = 8;
40static unsigned int dcc_timeout = 300;
41/* This is slow, but it's simple. --RR */
2669d63d 42static char *irc_buffer;
e45b1be8 43static DEFINE_SPINLOCK(irc_buffer_lock);
1da177e4
LT
44
45unsigned int (*ip_nat_irc_hook)(struct sk_buff **pskb,
46 enum ip_conntrack_info ctinfo,
47 unsigned int matchoff,
48 unsigned int matchlen,
49 struct ip_conntrack_expect *exp);
50EXPORT_SYMBOL_GPL(ip_nat_irc_hook);
51
52MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
53MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
54MODULE_LICENSE("GPL");
2fce76af 55module_param_array(ports, ushort, &ports_c, 0400);
1da177e4
LT
56MODULE_PARM_DESC(ports, "port numbers of IRC servers");
57module_param(max_dcc_channels, int, 0400);
58MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per IRC session");
59module_param(dcc_timeout, int, 0400);
60MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
61
62static char *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " };
63#define MINMATCHLEN 5
64
65#if 0
66#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \
67 __FILE__, __FUNCTION__ , ## args)
68#else
69#define DEBUGP(format, args...)
70#endif
71
72static int parse_dcc(char *data, char *data_end, u_int32_t *ip,
73 u_int16_t *port, char **ad_beg_p, char **ad_end_p)
74/* tries to get the ip_addr and port out of a dcc command
75 return value: -1 on failure, 0 on success
76 data pointer to first byte of DCC command data
77 data_end pointer to last byte of dcc command data
78 ip returns parsed ip of dcc command
79 port returns parsed port of dcc command
80 ad_beg_p returns pointer to first byte of addr data
81 ad_end_p returns pointer to last byte of addr data */
82{
83
84 /* at least 12: "AAAAAAAA P\1\n" */
85 while (*data++ != ' ')
86 if (data > data_end - 12)
87 return -1;
88
89 *ad_beg_p = data;
90 *ip = simple_strtoul(data, &data, 10);
91
92 /* skip blanks between ip and port */
93 while (*data == ' ') {
94 if (data >= data_end)
95 return -1;
96 data++;
97 }
98
99 *port = simple_strtoul(data, &data, 10);
100 *ad_end_p = data;
101
102 return 0;
103}
104
105static int help(struct sk_buff **pskb,
106 struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
107{
108 unsigned int dataoff;
109 struct tcphdr _tcph, *th;
110 char *data, *data_limit, *ib_ptr;
111 int dir = CTINFO2DIR(ctinfo);
112 struct ip_conntrack_expect *exp;
113 u32 seq;
114 u_int32_t dcc_ip;
115 u_int16_t dcc_port;
116 int i, ret = NF_ACCEPT;
117 char *addr_beg_p, *addr_end_p;
118
119 DEBUGP("entered\n");
120
121 /* If packet is coming from IRC server */
122 if (dir == IP_CT_DIR_REPLY)
123 return NF_ACCEPT;
124
125 /* Until there's been traffic both ways, don't look in packets. */
126 if (ctinfo != IP_CT_ESTABLISHED
127 && ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {
128 DEBUGP("Conntrackinfo = %u\n", ctinfo);
129 return NF_ACCEPT;
130 }
131
132 /* Not a full tcp header? */
133 th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4,
134 sizeof(_tcph), &_tcph);
135 if (th == NULL)
136 return NF_ACCEPT;
137
138 /* No data? */
139 dataoff = (*pskb)->nh.iph->ihl*4 + th->doff*4;
140 if (dataoff >= (*pskb)->len)
141 return NF_ACCEPT;
142
e45b1be8 143 spin_lock_bh(&irc_buffer_lock);
1da177e4
LT
144 ib_ptr = skb_header_pointer(*pskb, dataoff,
145 (*pskb)->len - dataoff, irc_buffer);
146 BUG_ON(ib_ptr == NULL);
147
148 data = ib_ptr;
149 data_limit = ib_ptr + (*pskb)->len - dataoff;
150
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)) {
155 data++;
156 continue;
157 }
158
159 data += 5;
160 /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
161
162 DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n",
163 NIPQUAD(iph->saddr), ntohs(th->source),
164 NIPQUAD(iph->daddr), ntohs(th->dest));
165
166 for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
167 if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
168 /* no match */
169 continue;
170 }
171
172 DEBUGP("DCC %s detected\n", dccprotos[i]);
173 data += strlen(dccprotos[i]);
174 /* we have at least
175 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
176 * data left (== 14/13 bytes) */
177 if (parse_dcc((char *)data, data_limit, &dcc_ip,
178 &dcc_port, &addr_beg_p, &addr_end_p)) {
179 /* unable to parse */
180 DEBUGP("unable to parse dcc command\n");
181 continue;
182 }
183 DEBUGP("DCC bound ip/port: %u.%u.%u.%u:%u\n",
184 HIPQUAD(dcc_ip), dcc_port);
185
186 /* dcc_ip can be the internal OR external (NAT'ed) IP
187 * Tiago Sousa <mirage@kaotik.org> */
188 if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip)
189 && ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip != htonl(dcc_ip)) {
190 if (net_ratelimit())
191 printk(KERN_WARNING
192 "Forged DCC command from "
193 "%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
194 NIPQUAD(ct->tuplehash[dir].tuple.src.ip),
195 HIPQUAD(dcc_ip), dcc_port);
196
197 continue;
198 }
199
4acdbdbe 200 exp = ip_conntrack_expect_alloc(ct);
1da177e4
LT
201 if (exp == NULL) {
202 ret = NF_DROP;
203 goto out;
204 }
205
206 /* save position of address in dcc string,
207 * necessary for NAT */
208 DEBUGP("tcph->seq = %u\n", th->seq);
209 seq = ntohl(th->seq) + (addr_beg_p - ib_ptr);
210
211 /* We refer to the reverse direction ("!dir")
212 * tuples here, because we're expecting
213 * something in the other * direction.
214 * Doesn't matter unless NAT is happening. */
215 exp->tuple = ((struct ip_conntrack_tuple)
216 { { 0, { 0 } },
217 { ct->tuplehash[!dir].tuple.dst.ip,
218 { .tcp = { htons(dcc_port) } },
219 IPPROTO_TCP }});
220 exp->mask = ((struct ip_conntrack_tuple)
221 { { 0, { 0 } },
222 { 0xFFFFFFFF, { .tcp = { 0xFFFF } }, 0xFF }});
223 exp->expectfn = NULL;
2248bcfc 224 exp->flags = 0;
1da177e4
LT
225 if (ip_nat_irc_hook)
226 ret = ip_nat_irc_hook(pskb, ctinfo,
227 addr_beg_p - ib_ptr,
228 addr_end_p - addr_beg_p,
229 exp);
4acdbdbe 230 else if (ip_conntrack_expect_related(exp) != 0)
1da177e4 231 ret = NF_DROP;
4acdbdbe 232 ip_conntrack_expect_put(exp);
1da177e4
LT
233 goto out;
234 } /* for .. NUM_DCCPROTO */
235 } /* while data < ... */
236
237 out:
e45b1be8 238 spin_unlock_bh(&irc_buffer_lock);
1da177e4
LT
239 return ret;
240}
241
242static struct ip_conntrack_helper irc_helpers[MAX_PORTS];
5cb30640 243static char irc_names[MAX_PORTS][sizeof("irc-65535")];
1da177e4
LT
244
245static void fini(void);
246
247static int __init init(void)
248{
249 int i, ret;
250 struct ip_conntrack_helper *hlpr;
251 char *tmpname;
252
253 if (max_dcc_channels < 1) {
254 printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n");
255 return -EBUSY;
256 }
257 if (dcc_timeout < 0) {
258 printk("ip_conntrack_irc: dcc_timeout must be a positive integer\n");
259 return -EBUSY;
260 }
2669d63d
HW
261
262 irc_buffer = kmalloc(65536, GFP_KERNEL);
263 if (!irc_buffer)
264 return -ENOMEM;
1da177e4
LT
265
266 /* If no port given, default to standard irc port */
267 if (ports_c == 0)
268 ports[ports_c++] = IRC_PORT;
269
270 for (i = 0; i < ports_c; i++) {
271 hlpr = &irc_helpers[i];
272 hlpr->tuple.src.u.tcp.port = htons(ports[i]);
273 hlpr->tuple.dst.protonum = IPPROTO_TCP;
274 hlpr->mask.src.u.tcp.port = 0xFFFF;
275 hlpr->mask.dst.protonum = 0xFF;
276 hlpr->max_expected = max_dcc_channels;
277 hlpr->timeout = dcc_timeout;
278 hlpr->me = THIS_MODULE;
279 hlpr->help = help;
280
281 tmpname = &irc_names[i][0];
282 if (ports[i] == IRC_PORT)
283 sprintf(tmpname, "irc");
284 else
285 sprintf(tmpname, "irc-%d", i);
286 hlpr->name = tmpname;
287
288 DEBUGP("port #%d: %d\n", i, ports[i]);
289
290 ret = ip_conntrack_helper_register(hlpr);
291
292 if (ret) {
293 printk("ip_conntrack_irc: ERROR registering port %d\n",
294 ports[i]);
295 fini();
296 return -EBUSY;
297 }
298 }
299 return 0;
300}
301
302/* This function is intentionally _NOT_ defined as __exit, because
303 * it is needed by the init function */
304static void fini(void)
305{
306 int i;
307 for (i = 0; i < ports_c; i++) {
308 DEBUGP("unregistering port %d\n",
309 ports[i]);
310 ip_conntrack_helper_unregister(&irc_helpers[i]);
311 }
2669d63d 312 kfree(irc_buffer);
1da177e4
LT
313}
314
315module_init(init);
316module_exit(fini);
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