Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6
[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 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);
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 *const 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, const 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         const struct iphdr *iph;
97         const struct tcphdr *th;
98         struct tcphdr _tcph;
99         const char *data_limit;
100         char *data, *ib_ptr;
101         int dir = CTINFO2DIR(ctinfo);
102         struct nf_conntrack_expect *exp;
103         struct nf_conntrack_tuple *tuple;
104         u_int32_t dcc_ip;
105         u_int16_t dcc_port;
106         __be16 port;
107         int i, ret = NF_ACCEPT;
108         char *addr_beg_p, *addr_end_p;
109         typeof(nf_nat_irc_hook) nf_nat_irc;
110
111         /* If packet is coming from IRC server */
112         if (dir == IP_CT_DIR_REPLY)
113                 return NF_ACCEPT;
114
115         /* Until there's been traffic both ways, don't look in packets. */
116         if (ctinfo != IP_CT_ESTABLISHED &&
117             ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
118                 return NF_ACCEPT;
119
120         /* Not a full tcp header? */
121         th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
122         if (th == NULL)
123                 return NF_ACCEPT;
124
125         /* No data? */
126         dataoff = protoff + th->doff*4;
127         if (dataoff >= skb->len)
128                 return NF_ACCEPT;
129
130         spin_lock_bh(&irc_buffer_lock);
131         ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
132                                     irc_buffer);
133         BUG_ON(ib_ptr == NULL);
134
135         data = ib_ptr;
136         data_limit = ib_ptr + skb->len - dataoff;
137
138         /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
139          * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
140         while (data < data_limit - (19 + MINMATCHLEN)) {
141                 if (memcmp(data, "\1DCC ", 5)) {
142                         data++;
143                         continue;
144                 }
145                 data += 5;
146                 /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
147
148                 iph = ip_hdr(skb);
149                 pr_debug("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u\n",
150                          NIPQUAD(iph->saddr), ntohs(th->source),
151                          NIPQUAD(iph->daddr), ntohs(th->dest));
152
153                 for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
154                         if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
155                                 /* no match */
156                                 continue;
157                         }
158                         data += strlen(dccprotos[i]);
159                         pr_debug("DCC %s detected\n", dccprotos[i]);
160
161                         /* we have at least
162                          * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
163                          * data left (== 14/13 bytes) */
164                         if (parse_dcc(data, data_limit, &dcc_ip,
165                                        &dcc_port, &addr_beg_p, &addr_end_p)) {
166                                 pr_debug("unable to parse dcc command\n");
167                                 continue;
168                         }
169                         pr_debug("DCC bound ip/port: %u.%u.%u.%u:%u\n",
170                                  HIPQUAD(dcc_ip), dcc_port);
171
172                         /* dcc_ip can be the internal OR external (NAT'ed) IP */
173                         tuple = &ct->tuplehash[dir].tuple;
174                         if (tuple->src.u3.ip != htonl(dcc_ip) &&
175                             tuple->dst.u3.ip != htonl(dcc_ip)) {
176                                 if (net_ratelimit())
177                                         printk(KERN_WARNING
178                                                 "Forged DCC command from "
179                                                 "%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
180                                                 NIPQUAD(tuple->src.u3.ip),
181                                                 HIPQUAD(dcc_ip), dcc_port);
182                                 continue;
183                         }
184
185                         exp = nf_ct_expect_alloc(ct);
186                         if (exp == NULL) {
187                                 ret = NF_DROP;
188                                 goto out;
189                         }
190                         tuple = &ct->tuplehash[!dir].tuple;
191                         port = htons(dcc_port);
192                         nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
193                                           tuple->src.l3num,
194                                           NULL, &tuple->dst.u3,
195                                           IPPROTO_TCP, NULL, &port);
196
197                         nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
198                         if (nf_nat_irc && ct->status & IPS_NAT_MASK)
199                                 ret = nf_nat_irc(skb, ctinfo,
200                                                  addr_beg_p - ib_ptr,
201                                                  addr_end_p - addr_beg_p,
202                                                  exp);
203                         else if (nf_ct_expect_related(exp) != 0)
204                                 ret = NF_DROP;
205                         nf_ct_expect_put(exp);
206                         goto out;
207                 }
208         }
209  out:
210         spin_unlock_bh(&irc_buffer_lock);
211         return ret;
212 }
213
214 static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
215 static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly;
216 static struct nf_conntrack_expect_policy irc_exp_policy;
217
218 static void nf_conntrack_irc_fini(void);
219
220 static int __init nf_conntrack_irc_init(void)
221 {
222         int i, ret;
223         char *tmpname;
224
225         if (max_dcc_channels < 1) {
226                 printk("nf_ct_irc: max_dcc_channels must not be zero\n");
227                 return -EINVAL;
228         }
229
230         irc_exp_policy.max_expected = max_dcc_channels;
231         irc_exp_policy.timeout = dcc_timeout;
232
233         irc_buffer = kmalloc(65536, GFP_KERNEL);
234         if (!irc_buffer)
235                 return -ENOMEM;
236
237         /* If no port given, default to standard irc port */
238         if (ports_c == 0)
239                 ports[ports_c++] = IRC_PORT;
240
241         for (i = 0; i < ports_c; i++) {
242                 irc[i].tuple.src.l3num = AF_INET;
243                 irc[i].tuple.src.u.tcp.port = htons(ports[i]);
244                 irc[i].tuple.dst.protonum = IPPROTO_TCP;
245                 irc[i].expect_policy = &irc_exp_policy;
246                 irc[i].me = THIS_MODULE;
247                 irc[i].help = help;
248
249                 tmpname = &irc_names[i][0];
250                 if (ports[i] == IRC_PORT)
251                         sprintf(tmpname, "irc");
252                 else
253                         sprintf(tmpname, "irc-%u", i);
254                 irc[i].name = tmpname;
255
256                 ret = nf_conntrack_helper_register(&irc[i]);
257                 if (ret) {
258                         printk("nf_ct_irc: failed to register helper "
259                                "for pf: %u port: %u\n",
260                                irc[i].tuple.src.l3num, ports[i]);
261                         nf_conntrack_irc_fini();
262                         return ret;
263                 }
264         }
265         return 0;
266 }
267
268 /* This function is intentionally _NOT_ defined as __exit, because
269  * it is needed by the init function */
270 static void nf_conntrack_irc_fini(void)
271 {
272         int i;
273
274         for (i = 0; i < ports_c; i++)
275                 nf_conntrack_helper_unregister(&irc[i]);
276         kfree(irc_buffer);
277 }
278
279 module_init(nf_conntrack_irc_init);
280 module_exit(nf_conntrack_irc_fini);