[NETFILTER]: Kill lockhelp.h
[linux-2.6.git] / net / ipv4 / netfilter / ip_conntrack_irc.c
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
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
37 static int ports[MAX_PORTS];
38 static int ports_c;
39 static int max_dcc_channels = 8;
40 static unsigned int dcc_timeout = 300;
41 /* This is slow, but it's simple. --RR */
42 static char irc_buffer[65536];
43 static DEFINE_SPINLOCK(irc_buffer_lock);
44
45 unsigned 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);
50 EXPORT_SYMBOL_GPL(ip_nat_irc_hook);
51
52 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
53 MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
54 MODULE_LICENSE("GPL");
55 module_param_array(ports, int, &ports_c, 0400);
56 MODULE_PARM_DESC(ports, "port numbers of IRC servers");
57 module_param(max_dcc_channels, int, 0400);
58 MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per IRC session");
59 module_param(dcc_timeout, int, 0400);
60 MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
61
62 static 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
72 static 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
105 static 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
143         spin_lock_bh(&irc_buffer_lock);
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
200                         exp = ip_conntrack_expect_alloc();
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;
224                         exp->master = ct;
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);
230                         else if (ip_conntrack_expect_related(exp) != 0) {
231                                 ip_conntrack_expect_free(exp);
232                                 ret = NF_DROP;
233                         }
234                         goto out;
235                 } /* for .. NUM_DCCPROTO */
236         } /* while data < ... */
237
238  out:
239         spin_unlock_bh(&irc_buffer_lock);
240         return ret;
241 }
242
243 static struct ip_conntrack_helper irc_helpers[MAX_PORTS];
244 static char irc_names[MAX_PORTS][10];
245
246 static void fini(void);
247
248 static int __init init(void)
249 {
250         int i, ret;
251         struct ip_conntrack_helper *hlpr;
252         char *tmpname;
253
254         if (max_dcc_channels < 1) {
255                 printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n");
256                 return -EBUSY;
257         }
258         if (dcc_timeout < 0) {
259                 printk("ip_conntrack_irc: dcc_timeout must be a positive integer\n");
260                 return -EBUSY;
261         }
262         
263         /* If no port given, default to standard irc port */
264         if (ports_c == 0)
265                 ports[ports_c++] = IRC_PORT;
266
267         for (i = 0; i < ports_c; i++) {
268                 hlpr = &irc_helpers[i];
269                 hlpr->tuple.src.u.tcp.port = htons(ports[i]);
270                 hlpr->tuple.dst.protonum = IPPROTO_TCP;
271                 hlpr->mask.src.u.tcp.port = 0xFFFF;
272                 hlpr->mask.dst.protonum = 0xFF;
273                 hlpr->max_expected = max_dcc_channels;
274                 hlpr->timeout = dcc_timeout;
275                 hlpr->me = THIS_MODULE;
276                 hlpr->help = help;
277
278                 tmpname = &irc_names[i][0];
279                 if (ports[i] == IRC_PORT)
280                         sprintf(tmpname, "irc");
281                 else
282                         sprintf(tmpname, "irc-%d", i);
283                 hlpr->name = tmpname;
284
285                 DEBUGP("port #%d: %d\n", i, ports[i]);
286
287                 ret = ip_conntrack_helper_register(hlpr);
288
289                 if (ret) {
290                         printk("ip_conntrack_irc: ERROR registering port %d\n",
291                                 ports[i]);
292                         fini();
293                         return -EBUSY;
294                 }
295         }
296         return 0;
297 }
298
299 /* This function is intentionally _NOT_ defined as __exit, because 
300  * it is needed by the init function */
301 static void fini(void)
302 {
303         int i;
304         for (i = 0; i < ports_c; i++) {
305                 DEBUGP("unregistering port %d\n",
306                        ports[i]);
307                 ip_conntrack_helper_unregister(&irc_helpers[i]);
308         }
309 }
310
311 module_init(init);
312 module_exit(fini);