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869f37d8 PM |
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> | |
0d53778e | 15 | #include <linux/ip.h> |
869f37d8 PM |
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]; | |
2f0d2f10 | 26 | static unsigned int ports_c; |
869f37d8 PM |
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 | ||
3db05fea | 33 | unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb, |
869f37d8 PM |
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"); | |
4dc06f96 | 44 | MODULE_ALIAS_NFCT_HELPER("irc"); |
869f37d8 PM |
45 | |
46 | module_param_array(ports, ushort, &ports_c, 0400); | |
47 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); | |
48 | module_param(max_dcc_channels, uint, 0400); | |
49 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " | |
50 | "IRC session"); | |
51 | module_param(dcc_timeout, uint, 0400); | |
52 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); | |
53 | ||
58c0fb0d | 54 | static const char *const dccprotos[] = { |
869f37d8 PM |
55 | "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " |
56 | }; | |
57 | ||
58 | #define MINMATCHLEN 5 | |
59 | ||
869f37d8 PM |
60 | /* tries to get the ip_addr and port out of a dcc command |
61 | * return value: -1 on failure, 0 on success | |
62 | * data pointer to first byte of DCC command data | |
63 | * data_end pointer to last byte of dcc command data | |
64 | * ip returns parsed ip of dcc command | |
65 | * port returns parsed port of dcc command | |
66 | * ad_beg_p returns pointer to first byte of addr data | |
67 | * ad_end_p returns pointer to last byte of addr data | |
68 | */ | |
f9409649 | 69 | static int parse_dcc(char *data, const char *data_end, __be32 *ip, |
869f37d8 PM |
70 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
71 | { | |
e3b802ba PM |
72 | char *tmp; |
73 | ||
869f37d8 PM |
74 | /* at least 12: "AAAAAAAA P\1\n" */ |
75 | while (*data++ != ' ') | |
76 | if (data > data_end - 12) | |
77 | return -1; | |
78 | ||
e3b802ba PM |
79 | /* Make sure we have a newline character within the packet boundaries |
80 | * because simple_strtoul parses until the first invalid character. */ | |
81 | for (tmp = data; tmp <= data_end; tmp++) | |
82 | if (*tmp == '\n') | |
83 | break; | |
84 | if (tmp > data_end || *tmp != '\n') | |
85 | return -1; | |
86 | ||
869f37d8 | 87 | *ad_beg_p = data; |
f9409649 | 88 | *ip = cpu_to_be32(simple_strtoul(data, &data, 10)); |
869f37d8 PM |
89 | |
90 | /* skip blanks between ip and port */ | |
91 | while (*data == ' ') { | |
92 | if (data >= data_end) | |
93 | return -1; | |
94 | data++; | |
95 | } | |
96 | ||
97 | *port = simple_strtoul(data, &data, 10); | |
98 | *ad_end_p = data; | |
99 | ||
100 | return 0; | |
101 | } | |
102 | ||
3db05fea | 103 | static int help(struct sk_buff *skb, unsigned int protoff, |
869f37d8 PM |
104 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
105 | { | |
106 | unsigned int dataoff; | |
58c0fb0d JE |
107 | const struct iphdr *iph; |
108 | const struct tcphdr *th; | |
109 | struct tcphdr _tcph; | |
110 | const char *data_limit; | |
111 | char *data, *ib_ptr; | |
869f37d8 PM |
112 | int dir = CTINFO2DIR(ctinfo); |
113 | struct nf_conntrack_expect *exp; | |
114 | struct nf_conntrack_tuple *tuple; | |
f9409649 | 115 | __be32 dcc_ip; |
869f37d8 PM |
116 | u_int16_t dcc_port; |
117 | __be16 port; | |
118 | int i, ret = NF_ACCEPT; | |
119 | char *addr_beg_p, *addr_end_p; | |
120 | typeof(nf_nat_irc_hook) nf_nat_irc; | |
121 | ||
122 | /* If packet is coming from IRC server */ | |
123 | if (dir == IP_CT_DIR_REPLY) | |
124 | return NF_ACCEPT; | |
125 | ||
126 | /* Until there's been traffic both ways, don't look in packets. */ | |
127 | if (ctinfo != IP_CT_ESTABLISHED && | |
128 | ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) | |
129 | return NF_ACCEPT; | |
130 | ||
131 | /* Not a full tcp header? */ | |
3db05fea | 132 | th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); |
869f37d8 PM |
133 | if (th == NULL) |
134 | return NF_ACCEPT; | |
135 | ||
136 | /* No data? */ | |
137 | dataoff = protoff + th->doff*4; | |
3db05fea | 138 | if (dataoff >= skb->len) |
869f37d8 PM |
139 | return NF_ACCEPT; |
140 | ||
141 | spin_lock_bh(&irc_buffer_lock); | |
3db05fea | 142 | ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, |
869f37d8 PM |
143 | irc_buffer); |
144 | BUG_ON(ib_ptr == NULL); | |
145 | ||
146 | data = ib_ptr; | |
3db05fea | 147 | data_limit = ib_ptr + skb->len - dataoff; |
869f37d8 PM |
148 | |
149 | /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24 | |
150 | * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */ | |
151 | while (data < data_limit - (19 + MINMATCHLEN)) { | |
152 | if (memcmp(data, "\1DCC ", 5)) { | |
153 | data++; | |
154 | continue; | |
155 | } | |
156 | data += 5; | |
157 | /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ | |
158 | ||
3db05fea | 159 | iph = ip_hdr(skb); |
14d5e834 HH |
160 | pr_debug("DCC found in master %pI4:%u %pI4:%u\n", |
161 | &iph->saddr, ntohs(th->source), | |
162 | &iph->daddr, ntohs(th->dest)); | |
869f37d8 PM |
163 | |
164 | for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { | |
165 | if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { | |
166 | /* no match */ | |
167 | continue; | |
168 | } | |
169 | data += strlen(dccprotos[i]); | |
0d53778e | 170 | pr_debug("DCC %s detected\n", dccprotos[i]); |
869f37d8 PM |
171 | |
172 | /* we have at least | |
173 | * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid | |
174 | * data left (== 14/13 bytes) */ | |
58c0fb0d | 175 | if (parse_dcc(data, data_limit, &dcc_ip, |
869f37d8 | 176 | &dcc_port, &addr_beg_p, &addr_end_p)) { |
0d53778e | 177 | pr_debug("unable to parse dcc command\n"); |
869f37d8 PM |
178 | continue; |
179 | } | |
f9409649 HH |
180 | |
181 | pr_debug("DCC bound ip/port: %pI4:%u\n", | |
182 | &dcc_ip, dcc_port); | |
869f37d8 PM |
183 | |
184 | /* dcc_ip can be the internal OR external (NAT'ed) IP */ | |
185 | tuple = &ct->tuplehash[dir].tuple; | |
f9409649 HH |
186 | if (tuple->src.u3.ip != dcc_ip && |
187 | tuple->dst.u3.ip != dcc_ip) { | |
869f37d8 PM |
188 | if (net_ratelimit()) |
189 | printk(KERN_WARNING | |
14d5e834 HH |
190 | "Forged DCC command from %pI4: %pI4:%u\n", |
191 | &tuple->src.u3.ip, | |
192 | &dcc_ip, dcc_port); | |
869f37d8 PM |
193 | continue; |
194 | } | |
195 | ||
6823645d | 196 | exp = nf_ct_expect_alloc(ct); |
869f37d8 PM |
197 | if (exp == NULL) { |
198 | ret = NF_DROP; | |
199 | goto out; | |
200 | } | |
201 | tuple = &ct->tuplehash[!dir].tuple; | |
202 | port = htons(dcc_port); | |
6002f266 PM |
203 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
204 | tuple->src.l3num, | |
6823645d PM |
205 | NULL, &tuple->dst.u3, |
206 | IPPROTO_TCP, NULL, &port); | |
869f37d8 PM |
207 | |
208 | nf_nat_irc = rcu_dereference(nf_nat_irc_hook); | |
209 | if (nf_nat_irc && ct->status & IPS_NAT_MASK) | |
3db05fea | 210 | ret = nf_nat_irc(skb, ctinfo, |
869f37d8 PM |
211 | addr_beg_p - ib_ptr, |
212 | addr_end_p - addr_beg_p, | |
213 | exp); | |
6823645d | 214 | else if (nf_ct_expect_related(exp) != 0) |
869f37d8 | 215 | ret = NF_DROP; |
6823645d | 216 | nf_ct_expect_put(exp); |
869f37d8 PM |
217 | goto out; |
218 | } | |
219 | } | |
220 | out: | |
221 | spin_unlock_bh(&irc_buffer_lock); | |
222 | return ret; | |
223 | } | |
224 | ||
225 | static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; | |
226 | static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly; | |
6002f266 | 227 | static struct nf_conntrack_expect_policy irc_exp_policy; |
869f37d8 PM |
228 | |
229 | static void nf_conntrack_irc_fini(void); | |
230 | ||
231 | static int __init nf_conntrack_irc_init(void) | |
232 | { | |
233 | int i, ret; | |
234 | char *tmpname; | |
235 | ||
236 | if (max_dcc_channels < 1) { | |
237 | printk("nf_ct_irc: max_dcc_channels must not be zero\n"); | |
238 | return -EINVAL; | |
239 | } | |
240 | ||
6002f266 PM |
241 | irc_exp_policy.max_expected = max_dcc_channels; |
242 | irc_exp_policy.timeout = dcc_timeout; | |
243 | ||
869f37d8 PM |
244 | irc_buffer = kmalloc(65536, GFP_KERNEL); |
245 | if (!irc_buffer) | |
246 | return -ENOMEM; | |
247 | ||
248 | /* If no port given, default to standard irc port */ | |
249 | if (ports_c == 0) | |
250 | ports[ports_c++] = IRC_PORT; | |
251 | ||
252 | for (i = 0; i < ports_c; i++) { | |
253 | irc[i].tuple.src.l3num = AF_INET; | |
254 | irc[i].tuple.src.u.tcp.port = htons(ports[i]); | |
255 | irc[i].tuple.dst.protonum = IPPROTO_TCP; | |
6002f266 | 256 | irc[i].expect_policy = &irc_exp_policy; |
869f37d8 PM |
257 | irc[i].me = THIS_MODULE; |
258 | irc[i].help = help; | |
259 | ||
260 | tmpname = &irc_names[i][0]; | |
261 | if (ports[i] == IRC_PORT) | |
262 | sprintf(tmpname, "irc"); | |
263 | else | |
264 | sprintf(tmpname, "irc-%u", i); | |
265 | irc[i].name = tmpname; | |
266 | ||
267 | ret = nf_conntrack_helper_register(&irc[i]); | |
268 | if (ret) { | |
269 | printk("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); |