ipvs: convert lblc scheduler to rcu
[linux-3.10.git] / 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 #include <linux/slab.h>
19
20 #include <net/netfilter/nf_conntrack.h>
21 #include <net/netfilter/nf_conntrack_expect.h>
22 #include <net/netfilter/nf_conntrack_helper.h>
23 #include <linux/netfilter/nf_conntrack_irc.h>
24
25 #define MAX_PORTS 8
26 static unsigned short ports[MAX_PORTS];
27 static unsigned int ports_c;
28 static unsigned int max_dcc_channels = 8;
29 static unsigned int dcc_timeout __read_mostly = 300;
30 /* This is slow, but it's simple. --RR */
31 static char *irc_buffer;
32 static DEFINE_SPINLOCK(irc_buffer_lock);
33
34 unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
35                                 enum ip_conntrack_info ctinfo,
36                                 unsigned int protoff,
37                                 unsigned int matchoff,
38                                 unsigned int matchlen,
39                                 struct nf_conntrack_expect *exp) __read_mostly;
40 EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
41
42 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
43 MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
44 MODULE_LICENSE("GPL");
45 MODULE_ALIAS("ip_conntrack_irc");
46 MODULE_ALIAS_NFCT_HELPER("irc");
47
48 module_param_array(ports, ushort, &ports_c, 0400);
49 MODULE_PARM_DESC(ports, "port numbers of IRC servers");
50 module_param(max_dcc_channels, uint, 0400);
51 MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
52                                    "IRC session");
53 module_param(dcc_timeout, uint, 0400);
54 MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
55
56 static const char *const dccprotos[] = {
57         "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
58 };
59
60 #define MINMATCHLEN     5
61
62 /* tries to get the ip_addr and port out of a dcc command
63  * return value: -1 on failure, 0 on success
64  *      data            pointer to first byte of DCC command data
65  *      data_end        pointer to last byte of dcc command data
66  *      ip              returns parsed ip of dcc command
67  *      port            returns parsed port of dcc command
68  *      ad_beg_p        returns pointer to first byte of addr data
69  *      ad_end_p        returns pointer to last byte of addr data
70  */
71 static int parse_dcc(char *data, const char *data_end, __be32 *ip,
72                      u_int16_t *port, char **ad_beg_p, char **ad_end_p)
73 {
74         char *tmp;
75
76         /* at least 12: "AAAAAAAA P\1\n" */
77         while (*data++ != ' ')
78                 if (data > data_end - 12)
79                         return -1;
80
81         /* Make sure we have a newline character within the packet boundaries
82          * because simple_strtoul parses until the first invalid character. */
83         for (tmp = data; tmp <= data_end; tmp++)
84                 if (*tmp == '\n')
85                         break;
86         if (tmp > data_end || *tmp != '\n')
87                 return -1;
88
89         *ad_beg_p = data;
90         *ip = cpu_to_be32(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 *skb, unsigned int protoff,
106                 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
107 {
108         unsigned int dataoff;
109         const struct iphdr *iph;
110         const struct tcphdr *th;
111         struct tcphdr _tcph;
112         const char *data_limit;
113         char *data, *ib_ptr;
114         int dir = CTINFO2DIR(ctinfo);
115         struct nf_conntrack_expect *exp;
116         struct nf_conntrack_tuple *tuple;
117         __be32 dcc_ip;
118         u_int16_t dcc_port;
119         __be16 port;
120         int i, ret = NF_ACCEPT;
121         char *addr_beg_p, *addr_end_p;
122         typeof(nf_nat_irc_hook) nf_nat_irc;
123
124         /* If packet is coming from IRC server */
125         if (dir == IP_CT_DIR_REPLY)
126                 return NF_ACCEPT;
127
128         /* Until there's been traffic both ways, don't look in packets. */
129         if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
130                 return NF_ACCEPT;
131
132         /* Not a full tcp header? */
133         th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
134         if (th == NULL)
135                 return NF_ACCEPT;
136
137         /* No data? */
138         dataoff = protoff + th->doff*4;
139         if (dataoff >= skb->len)
140                 return NF_ACCEPT;
141
142         spin_lock_bh(&irc_buffer_lock);
143         ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
144                                     irc_buffer);
145         BUG_ON(ib_ptr == NULL);
146
147         data = ib_ptr;
148         data_limit = ib_ptr + skb->len - dataoff;
149
150         /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
151          * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
152         while (data < data_limit - (19 + MINMATCHLEN)) {
153                 if (memcmp(data, "\1DCC ", 5)) {
154                         data++;
155                         continue;
156                 }
157                 data += 5;
158                 /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
159
160                 iph = ip_hdr(skb);
161                 pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
162                          &iph->saddr, ntohs(th->source),
163                          &iph->daddr, ntohs(th->dest));
164
165                 for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
166                         if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
167                                 /* no match */
168                                 continue;
169                         }
170                         data += strlen(dccprotos[i]);
171                         pr_debug("DCC %s detected\n", dccprotos[i]);
172
173                         /* we have at least
174                          * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
175                          * data left (== 14/13 bytes) */
176                         if (parse_dcc(data, data_limit, &dcc_ip,
177                                        &dcc_port, &addr_beg_p, &addr_end_p)) {
178                                 pr_debug("unable to parse dcc command\n");
179                                 continue;
180                         }
181
182                         pr_debug("DCC bound ip/port: %pI4:%u\n",
183                                  &dcc_ip, dcc_port);
184
185                         /* dcc_ip can be the internal OR external (NAT'ed) IP */
186                         tuple = &ct->tuplehash[dir].tuple;
187                         if (tuple->src.u3.ip != dcc_ip &&
188                             tuple->dst.u3.ip != dcc_ip) {
189                                 net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n",
190                                                      &tuple->src.u3.ip,
191                                                      &dcc_ip, dcc_port);
192                                 continue;
193                         }
194
195                         exp = nf_ct_expect_alloc(ct);
196                         if (exp == NULL) {
197                                 nf_ct_helper_log(skb, ct,
198                                                  "cannot alloc expectation");
199                                 ret = NF_DROP;
200                                 goto out;
201                         }
202                         tuple = &ct->tuplehash[!dir].tuple;
203                         port = htons(dcc_port);
204                         nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
205                                           tuple->src.l3num,
206                                           NULL, &tuple->dst.u3,
207                                           IPPROTO_TCP, NULL, &port);
208
209                         nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
210                         if (nf_nat_irc && ct->status & IPS_NAT_MASK)
211                                 ret = nf_nat_irc(skb, ctinfo, protoff,
212                                                  addr_beg_p - ib_ptr,
213                                                  addr_end_p - addr_beg_p,
214                                                  exp);
215                         else if (nf_ct_expect_related(exp) != 0) {
216                                 nf_ct_helper_log(skb, ct,
217                                                  "cannot add expectation");
218                                 ret = NF_DROP;
219                         }
220                         nf_ct_expect_put(exp);
221                         goto out;
222                 }
223         }
224  out:
225         spin_unlock_bh(&irc_buffer_lock);
226         return ret;
227 }
228
229 static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
230 static struct nf_conntrack_expect_policy irc_exp_policy;
231
232 static void nf_conntrack_irc_fini(void);
233
234 static int __init nf_conntrack_irc_init(void)
235 {
236         int i, ret;
237
238         if (max_dcc_channels < 1) {
239                 printk(KERN_ERR "nf_ct_irc: max_dcc_channels must not be zero\n");
240                 return -EINVAL;
241         }
242
243         irc_exp_policy.max_expected = max_dcc_channels;
244         irc_exp_policy.timeout = dcc_timeout;
245
246         irc_buffer = kmalloc(65536, GFP_KERNEL);
247         if (!irc_buffer)
248                 return -ENOMEM;
249
250         /* If no port given, default to standard irc port */
251         if (ports_c == 0)
252                 ports[ports_c++] = IRC_PORT;
253
254         for (i = 0; i < ports_c; i++) {
255                 irc[i].tuple.src.l3num = AF_INET;
256                 irc[i].tuple.src.u.tcp.port = htons(ports[i]);
257                 irc[i].tuple.dst.protonum = IPPROTO_TCP;
258                 irc[i].expect_policy = &irc_exp_policy;
259                 irc[i].me = THIS_MODULE;
260                 irc[i].help = help;
261
262                 if (ports[i] == IRC_PORT)
263                         sprintf(irc[i].name, "irc");
264                 else
265                         sprintf(irc[i].name, "irc-%u", i);
266
267                 ret = nf_conntrack_helper_register(&irc[i]);
268                 if (ret) {
269                         printk(KERN_ERR "nf_ct_irc: failed to register helper "
270                                "for pf: %u port: %u\n",
271                                irc[i].tuple.src.l3num, ports[i]);
272                         nf_conntrack_irc_fini();
273                         return ret;
274                 }
275         }
276         return 0;
277 }
278
279 /* This function is intentionally _NOT_ defined as __exit, because
280  * it is needed by the init function */
281 static void nf_conntrack_irc_fini(void)
282 {
283         int i;
284
285         for (i = 0; i < ports_c; i++)
286                 nf_conntrack_helper_unregister(&irc[i]);
287         kfree(irc_buffer);
288 }
289
290 module_init(nf_conntrack_irc_init);
291 module_exit(nf_conntrack_irc_fini);