Commit | Line | Data |
---|---|---|
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 | ||
1da177e4 LT |
25 | #include <linux/module.h> |
26 | #include <linux/netfilter.h> | |
27 | #include <linux/ip.h> | |
28 | #include <net/checksum.h> | |
29 | #include <net/tcp.h> | |
30 | ||
1da177e4 LT |
31 | #include <linux/netfilter_ipv4/ip_conntrack_helper.h> |
32 | #include <linux/netfilter_ipv4/ip_conntrack_irc.h> | |
33 | #include <linux/moduleparam.h> | |
34 | ||
35 | #define MAX_PORTS 8 | |
2fce76af | 36 | static unsigned short ports[MAX_PORTS]; |
1da177e4 | 37 | static int ports_c; |
e7be6994 | 38 | static unsigned int max_dcc_channels = 8; |
1da177e4 LT |
39 | static unsigned int dcc_timeout = 300; |
40 | /* This is slow, but it's simple. --RR */ | |
2669d63d | 41 | static char *irc_buffer; |
e45b1be8 | 42 | static DEFINE_SPINLOCK(irc_buffer_lock); |
1da177e4 LT |
43 | |
44 | unsigned int (*ip_nat_irc_hook)(struct sk_buff **pskb, | |
45 | enum ip_conntrack_info ctinfo, | |
46 | unsigned int matchoff, | |
47 | unsigned int matchlen, | |
48 | struct ip_conntrack_expect *exp); | |
49 | EXPORT_SYMBOL_GPL(ip_nat_irc_hook); | |
50 | ||
51 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); | |
52 | MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); | |
53 | MODULE_LICENSE("GPL"); | |
2fce76af | 54 | module_param_array(ports, ushort, &ports_c, 0400); |
1da177e4 | 55 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); |
e7be6994 | 56 | module_param(max_dcc_channels, uint, 0400); |
1da177e4 | 57 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per IRC session"); |
e7be6994 | 58 | module_param(dcc_timeout, uint, 0400); |
1da177e4 LT |
59 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); |
60 | ||
9b5b5cff | 61 | static const char *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " }; |
1da177e4 LT |
62 | #define MINMATCHLEN 5 |
63 | ||
64 | #if 0 | |
65 | #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \ | |
66 | __FILE__, __FUNCTION__ , ## args) | |
67 | #else | |
68 | #define DEBUGP(format, args...) | |
69 | #endif | |
70 | ||
71 | static int parse_dcc(char *data, char *data_end, u_int32_t *ip, | |
72 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) | |
73 | /* tries to get the ip_addr and port out of a dcc command | |
74 | return value: -1 on failure, 0 on success | |
75 | data pointer to first byte of DCC command data | |
76 | data_end pointer to last byte of dcc command data | |
77 | ip returns parsed ip of dcc command | |
78 | port returns parsed port of dcc command | |
79 | ad_beg_p returns pointer to first byte of addr data | |
80 | ad_end_p returns pointer to last byte of addr data */ | |
81 | { | |
82 | ||
83 | /* at least 12: "AAAAAAAA P\1\n" */ | |
84 | while (*data++ != ' ') | |
85 | if (data > data_end - 12) | |
86 | return -1; | |
87 | ||
88 | *ad_beg_p = data; | |
89 | *ip = simple_strtoul(data, &data, 10); | |
90 | ||
91 | /* skip blanks between ip and port */ | |
92 | while (*data == ' ') { | |
93 | if (data >= data_end) | |
94 | return -1; | |
95 | data++; | |
96 | } | |
97 | ||
98 | *port = simple_strtoul(data, &data, 10); | |
99 | *ad_end_p = data; | |
100 | ||
101 | return 0; | |
102 | } | |
103 | ||
104 | static int help(struct sk_buff **pskb, | |
105 | struct ip_conntrack *ct, enum ip_conntrack_info ctinfo) | |
106 | { | |
107 | unsigned int dataoff; | |
108 | struct tcphdr _tcph, *th; | |
109 | char *data, *data_limit, *ib_ptr; | |
110 | int dir = CTINFO2DIR(ctinfo); | |
111 | struct ip_conntrack_expect *exp; | |
112 | u32 seq; | |
113 | u_int32_t dcc_ip; | |
114 | u_int16_t dcc_port; | |
115 | int i, ret = NF_ACCEPT; | |
116 | char *addr_beg_p, *addr_end_p; | |
337fbc41 | 117 | typeof(ip_nat_irc_hook) ip_nat_irc; |
1da177e4 LT |
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 } }, | |
cdcb71bf AV |
222 | { htonl(0xFFFFFFFF), |
223 | { .tcp = { htons(0xFFFF) } }, 0xFF }}); | |
1da177e4 | 224 | exp->expectfn = NULL; |
2248bcfc | 225 | exp->flags = 0; |
337fbc41 PM |
226 | ip_nat_irc = rcu_dereference(ip_nat_irc_hook); |
227 | if (ip_nat_irc) | |
228 | ret = ip_nat_irc(pskb, ctinfo, | |
229 | addr_beg_p - ib_ptr, | |
230 | addr_end_p - addr_beg_p, | |
231 | exp); | |
4acdbdbe | 232 | else if (ip_conntrack_expect_related(exp) != 0) |
1da177e4 | 233 | ret = NF_DROP; |
4acdbdbe | 234 | ip_conntrack_expect_put(exp); |
1da177e4 LT |
235 | goto out; |
236 | } /* for .. NUM_DCCPROTO */ | |
237 | } /* while data < ... */ | |
238 | ||
239 | out: | |
e45b1be8 | 240 | spin_unlock_bh(&irc_buffer_lock); |
1da177e4 LT |
241 | return ret; |
242 | } | |
243 | ||
244 | static struct ip_conntrack_helper irc_helpers[MAX_PORTS]; | |
5cb30640 | 245 | static char irc_names[MAX_PORTS][sizeof("irc-65535")]; |
1da177e4 | 246 | |
65b4b4e8 | 247 | static void ip_conntrack_irc_fini(void); |
1da177e4 | 248 | |
65b4b4e8 | 249 | static int __init ip_conntrack_irc_init(void) |
1da177e4 LT |
250 | { |
251 | int i, ret; | |
252 | struct ip_conntrack_helper *hlpr; | |
253 | char *tmpname; | |
254 | ||
255 | if (max_dcc_channels < 1) { | |
256 | printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n"); | |
257 | return -EBUSY; | |
258 | } | |
2669d63d HW |
259 | |
260 | irc_buffer = kmalloc(65536, GFP_KERNEL); | |
261 | if (!irc_buffer) | |
262 | return -ENOMEM; | |
1da177e4 LT |
263 | |
264 | /* If no port given, default to standard irc port */ | |
265 | if (ports_c == 0) | |
266 | ports[ports_c++] = IRC_PORT; | |
267 | ||
268 | for (i = 0; i < ports_c; i++) { | |
269 | hlpr = &irc_helpers[i]; | |
270 | hlpr->tuple.src.u.tcp.port = htons(ports[i]); | |
271 | hlpr->tuple.dst.protonum = IPPROTO_TCP; | |
cdcb71bf | 272 | hlpr->mask.src.u.tcp.port = htons(0xFFFF); |
1da177e4 LT |
273 | hlpr->mask.dst.protonum = 0xFF; |
274 | hlpr->max_expected = max_dcc_channels; | |
275 | hlpr->timeout = dcc_timeout; | |
276 | hlpr->me = THIS_MODULE; | |
277 | hlpr->help = help; | |
278 | ||
279 | tmpname = &irc_names[i][0]; | |
280 | if (ports[i] == IRC_PORT) | |
281 | sprintf(tmpname, "irc"); | |
282 | else | |
283 | sprintf(tmpname, "irc-%d", i); | |
284 | hlpr->name = tmpname; | |
285 | ||
286 | DEBUGP("port #%d: %d\n", i, ports[i]); | |
287 | ||
288 | ret = ip_conntrack_helper_register(hlpr); | |
289 | ||
290 | if (ret) { | |
291 | printk("ip_conntrack_irc: ERROR registering port %d\n", | |
292 | ports[i]); | |
65b4b4e8 | 293 | ip_conntrack_irc_fini(); |
1da177e4 LT |
294 | return -EBUSY; |
295 | } | |
296 | } | |
297 | return 0; | |
298 | } | |
299 | ||
300 | /* This function is intentionally _NOT_ defined as __exit, because | |
301 | * it is needed by the init function */ | |
65b4b4e8 | 302 | static void ip_conntrack_irc_fini(void) |
1da177e4 LT |
303 | { |
304 | int i; | |
305 | for (i = 0; i < ports_c; i++) { | |
306 | DEBUGP("unregistering port %d\n", | |
307 | ports[i]); | |
308 | ip_conntrack_helper_unregister(&irc_helpers[i]); | |
309 | } | |
2669d63d | 310 | kfree(irc_buffer); |
1da177e4 LT |
311 | } |
312 | ||
65b4b4e8 AM |
313 | module_init(ip_conntrack_irc_init); |
314 | module_exit(ip_conntrack_irc_fini); |