Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shaggy...
[linux-2.6] / net / netfilter / nf_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  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License
7  * as published by the Free Software Foundation; either version
8  * 2 of the License, or (at your option) any later version.
9  */
10
11 #include <linux/module.h>
12 #include <linux/moduleparam.h>
13 #include <linux/skbuff.h>
14 #include <linux/in.h>
15 #include <linux/ip.h>
16 #include <linux/tcp.h>
17 #include <linux/netfilter.h>
18
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>
23
24 #define MAX_PORTS 8
25 static unsigned short ports[MAX_PORTS];
26 static 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);
32
33 unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
34                                 enum ip_conntrack_info ctinfo,
35                                 unsigned int matchoff,
36                                 unsigned int matchlen,
37                                 struct nf_conntrack_expect *exp) __read_mostly;
38 EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
39
40 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
41 MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
42 MODULE_LICENSE("GPL");
43 MODULE_ALIAS("ip_conntrack_irc");
44
45 module_param_array(ports, ushort, &ports_c, 0400);
46 MODULE_PARM_DESC(ports, "port numbers of IRC servers");
47 module_param(max_dcc_channels, uint, 0400);
48 MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
49                                    "IRC session");
50 module_param(dcc_timeout, uint, 0400);
51 MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
52
53 static const char *dccprotos[] = {
54         "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
55 };
56
57 #define MINMATCHLEN     5
58
59 /* tries to get the ip_addr and port out of a dcc command
60  * return value: -1 on failure, 0 on success
61  *      data            pointer to first byte of DCC command data
62  *      data_end        pointer to last byte of dcc command data
63  *      ip              returns parsed ip of dcc command
64  *      port            returns parsed port of dcc command
65  *      ad_beg_p        returns pointer to first byte of addr data
66  *      ad_end_p        returns pointer to last byte of addr data
67  */
68 static int parse_dcc(char *data, char *data_end, u_int32_t *ip,
69                      u_int16_t *port, char **ad_beg_p, char **ad_end_p)
70 {
71         /* at least 12: "AAAAAAAA P\1\n" */
72         while (*data++ != ' ')
73                 if (data > data_end - 12)
74                         return -1;
75
76         *ad_beg_p = data;
77         *ip = simple_strtoul(data, &data, 10);
78
79         /* skip blanks between ip and port */
80         while (*data == ' ') {
81                 if (data >= data_end)
82                         return -1;
83                 data++;
84         }
85
86         *port = simple_strtoul(data, &data, 10);
87         *ad_end_p = data;
88
89         return 0;
90 }
91
92 static int help(struct sk_buff *skb, unsigned int protoff,
93                 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
94 {
95         unsigned int dataoff;
96         struct iphdr *iph;
97         struct tcphdr _tcph, *th;
98         char *data, *data_limit, *ib_ptr;
99         int dir = CTINFO2DIR(ctinfo);
100         struct nf_conntrack_expect *exp;
101         struct nf_conntrack_tuple *tuple;
102         u_int32_t dcc_ip;
103         u_int16_t dcc_port;
104         __be16 port;
105         int i, ret = NF_ACCEPT;
106         char *addr_beg_p, *addr_end_p;
107         typeof(nf_nat_irc_hook) nf_nat_irc;
108
109         /* If packet is coming from IRC server */
110         if (dir == IP_CT_DIR_REPLY)
111                 return NF_ACCEPT;
112
113         /* Until there's been traffic both ways, don't look in packets. */
114         if (ctinfo != IP_CT_ESTABLISHED &&
115             ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
116                 return NF_ACCEPT;
117
118         /* Not a full tcp header? */
119         th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
120         if (th == NULL)
121                 return NF_ACCEPT;
122
123         /* No data? */
124         dataoff = protoff + th->doff*4;
125         if (dataoff >= skb->len)
126                 return NF_ACCEPT;
127
128         spin_lock_bh(&irc_buffer_lock);
129         ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
130                                     irc_buffer);
131         BUG_ON(ib_ptr == NULL);
132
133         data = ib_ptr;
134         data_limit = ib_ptr + skb->len - dataoff;
135
136         /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
137          * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
138         while (data < data_limit - (19 + MINMATCHLEN)) {
139                 if (memcmp(data, "\1DCC ", 5)) {
140                         data++;
141                         continue;
142                 }
143                 data += 5;
144                 /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
145
146                 iph = ip_hdr(skb);
147                 pr_debug("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u\n",
148                          NIPQUAD(iph->saddr), ntohs(th->source),
149                          NIPQUAD(iph->daddr), ntohs(th->dest));
150
151                 for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
152                         if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
153                                 /* no match */
154                                 continue;
155                         }
156                         data += strlen(dccprotos[i]);
157                         pr_debug("DCC %s detected\n", dccprotos[i]);
158
159                         /* we have at least
160                          * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
161                          * data left (== 14/13 bytes) */
162                         if (parse_dcc((char *)data, data_limit, &dcc_ip,
163                                        &dcc_port, &addr_beg_p, &addr_end_p)) {
164                                 pr_debug("unable to parse dcc command\n");
165                                 continue;
166                         }
167                         pr_debug("DCC bound ip/port: %u.%u.%u.%u:%u\n",
168                                  HIPQUAD(dcc_ip), dcc_port);
169
170                         /* dcc_ip can be the internal OR external (NAT'ed) IP */
171                         tuple = &ct->tuplehash[dir].tuple;
172                         if (tuple->src.u3.ip != htonl(dcc_ip) &&
173                             tuple->dst.u3.ip != htonl(dcc_ip)) {
174                                 if (net_ratelimit())
175                                         printk(KERN_WARNING
176                                                 "Forged DCC command from "
177                                                 "%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
178                                                 NIPQUAD(tuple->src.u3.ip),
179                                                 HIPQUAD(dcc_ip), dcc_port);
180                                 continue;
181                         }
182
183                         exp = nf_ct_expect_alloc(ct);
184                         if (exp == NULL) {
185                                 ret = NF_DROP;
186                                 goto out;
187                         }
188                         tuple = &ct->tuplehash[!dir].tuple;
189                         port = htons(dcc_port);
190                         nf_ct_expect_init(exp, tuple->src.l3num,
191                                           NULL, &tuple->dst.u3,
192                                           IPPROTO_TCP, NULL, &port);
193
194                         nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
195                         if (nf_nat_irc && ct->status & IPS_NAT_MASK)
196                                 ret = nf_nat_irc(skb, ctinfo,
197                                                  addr_beg_p - ib_ptr,
198                                                  addr_end_p - addr_beg_p,
199                                                  exp);
200                         else if (nf_ct_expect_related(exp) != 0)
201                                 ret = NF_DROP;
202                         nf_ct_expect_put(exp);
203                         goto out;
204                 }
205         }
206  out:
207         spin_unlock_bh(&irc_buffer_lock);
208         return ret;
209 }
210
211 static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
212 static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly;
213
214 static void nf_conntrack_irc_fini(void);
215
216 static int __init nf_conntrack_irc_init(void)
217 {
218         int i, ret;
219         char *tmpname;
220
221         if (max_dcc_channels < 1) {
222                 printk("nf_ct_irc: max_dcc_channels must not be zero\n");
223                 return -EINVAL;
224         }
225
226         irc_buffer = kmalloc(65536, GFP_KERNEL);
227         if (!irc_buffer)
228                 return -ENOMEM;
229
230         /* If no port given, default to standard irc port */
231         if (ports_c == 0)
232                 ports[ports_c++] = IRC_PORT;
233
234         for (i = 0; i < ports_c; i++) {
235                 irc[i].tuple.src.l3num = AF_INET;
236                 irc[i].tuple.src.u.tcp.port = htons(ports[i]);
237                 irc[i].tuple.dst.protonum = IPPROTO_TCP;
238                 irc[i].max_expected = max_dcc_channels;
239                 irc[i].timeout = dcc_timeout;
240                 irc[i].me = THIS_MODULE;
241                 irc[i].help = help;
242
243                 tmpname = &irc_names[i][0];
244                 if (ports[i] == IRC_PORT)
245                         sprintf(tmpname, "irc");
246                 else
247                         sprintf(tmpname, "irc-%u", i);
248                 irc[i].name = tmpname;
249
250                 ret = nf_conntrack_helper_register(&irc[i]);
251                 if (ret) {
252                         printk("nf_ct_irc: failed to register helper "
253                                "for pf: %u port: %u\n",
254                                irc[i].tuple.src.l3num, ports[i]);
255                         nf_conntrack_irc_fini();
256                         return ret;
257                 }
258         }
259         return 0;
260 }
261
262 /* This function is intentionally _NOT_ defined as __exit, because
263  * it is needed by the init function */
264 static void nf_conntrack_irc_fini(void)
265 {
266         int i;
267
268         for (i = 0; i < ports_c; i++)
269                 nf_conntrack_helper_unregister(&irc[i]);
270         kfree(irc_buffer);
271 }
272
273 module_init(nf_conntrack_irc_init);
274 module_exit(nf_conntrack_irc_fini);