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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 | |
f229f6ce | 4 | * (C) 2006-2012 Patrick McHardy <kaber@trash.net> |
869f37d8 PM |
5 | * |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/moduleparam.h> | |
14 | #include <linux/skbuff.h> | |
15 | #include <linux/in.h> | |
0d53778e | 16 | #include <linux/ip.h> |
869f37d8 PM |
17 | #include <linux/tcp.h> |
18 | #include <linux/netfilter.h> | |
5a0e3ad6 | 19 | #include <linux/slab.h> |
869f37d8 PM |
20 | |
21 | #include <net/netfilter/nf_conntrack.h> | |
22 | #include <net/netfilter/nf_conntrack_expect.h> | |
23 | #include <net/netfilter/nf_conntrack_helper.h> | |
24 | #include <linux/netfilter/nf_conntrack_irc.h> | |
25 | ||
26 | #define MAX_PORTS 8 | |
27 | static unsigned short ports[MAX_PORTS]; | |
2f0d2f10 | 28 | static unsigned int ports_c; |
869f37d8 PM |
29 | static unsigned int max_dcc_channels = 8; |
30 | static unsigned int dcc_timeout __read_mostly = 300; | |
31 | /* This is slow, but it's simple. --RR */ | |
32 | static char *irc_buffer; | |
33 | static DEFINE_SPINLOCK(irc_buffer_lock); | |
34 | ||
3db05fea | 35 | unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb, |
869f37d8 | 36 | enum ip_conntrack_info ctinfo, |
051966c0 | 37 | unsigned int protoff, |
869f37d8 PM |
38 | unsigned int matchoff, |
39 | unsigned int matchlen, | |
40 | struct nf_conntrack_expect *exp) __read_mostly; | |
41 | EXPORT_SYMBOL_GPL(nf_nat_irc_hook); | |
42 | ||
43 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); | |
44 | MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); | |
45 | MODULE_LICENSE("GPL"); | |
46 | MODULE_ALIAS("ip_conntrack_irc"); | |
4dc06f96 | 47 | MODULE_ALIAS_NFCT_HELPER("irc"); |
869f37d8 PM |
48 | |
49 | module_param_array(ports, ushort, &ports_c, 0400); | |
50 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); | |
51 | module_param(max_dcc_channels, uint, 0400); | |
52 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " | |
53 | "IRC session"); | |
54 | module_param(dcc_timeout, uint, 0400); | |
55 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); | |
56 | ||
58c0fb0d | 57 | static const char *const dccprotos[] = { |
869f37d8 PM |
58 | "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " |
59 | }; | |
60 | ||
61 | #define MINMATCHLEN 5 | |
62 | ||
869f37d8 PM |
63 | /* tries to get the ip_addr and port out of a dcc command |
64 | * return value: -1 on failure, 0 on success | |
65 | * data pointer to first byte of DCC command data | |
66 | * data_end pointer to last byte of dcc command data | |
67 | * ip returns parsed ip of dcc command | |
68 | * port returns parsed port of dcc command | |
69 | * ad_beg_p returns pointer to first byte of addr data | |
70 | * ad_end_p returns pointer to last byte of addr data | |
71 | */ | |
f9409649 | 72 | static int parse_dcc(char *data, const char *data_end, __be32 *ip, |
869f37d8 PM |
73 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
74 | { | |
e3b802ba PM |
75 | char *tmp; |
76 | ||
869f37d8 PM |
77 | /* at least 12: "AAAAAAAA P\1\n" */ |
78 | while (*data++ != ' ') | |
79 | if (data > data_end - 12) | |
80 | return -1; | |
81 | ||
e3b802ba PM |
82 | /* Make sure we have a newline character within the packet boundaries |
83 | * because simple_strtoul parses until the first invalid character. */ | |
84 | for (tmp = data; tmp <= data_end; tmp++) | |
85 | if (*tmp == '\n') | |
86 | break; | |
87 | if (tmp > data_end || *tmp != '\n') | |
88 | return -1; | |
89 | ||
869f37d8 | 90 | *ad_beg_p = data; |
f9409649 | 91 | *ip = cpu_to_be32(simple_strtoul(data, &data, 10)); |
869f37d8 PM |
92 | |
93 | /* skip blanks between ip and port */ | |
94 | while (*data == ' ') { | |
95 | if (data >= data_end) | |
96 | return -1; | |
97 | data++; | |
98 | } | |
99 | ||
100 | *port = simple_strtoul(data, &data, 10); | |
101 | *ad_end_p = data; | |
102 | ||
103 | return 0; | |
104 | } | |
105 | ||
3db05fea | 106 | static int help(struct sk_buff *skb, unsigned int protoff, |
869f37d8 PM |
107 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
108 | { | |
109 | unsigned int dataoff; | |
58c0fb0d JE |
110 | const struct iphdr *iph; |
111 | const struct tcphdr *th; | |
112 | struct tcphdr _tcph; | |
113 | const char *data_limit; | |
114 | char *data, *ib_ptr; | |
869f37d8 PM |
115 | int dir = CTINFO2DIR(ctinfo); |
116 | struct nf_conntrack_expect *exp; | |
117 | struct nf_conntrack_tuple *tuple; | |
f9409649 | 118 | __be32 dcc_ip; |
869f37d8 PM |
119 | u_int16_t dcc_port; |
120 | __be16 port; | |
121 | int i, ret = NF_ACCEPT; | |
122 | char *addr_beg_p, *addr_end_p; | |
123 | typeof(nf_nat_irc_hook) nf_nat_irc; | |
124 | ||
125 | /* If packet is coming from IRC server */ | |
126 | if (dir == IP_CT_DIR_REPLY) | |
127 | return NF_ACCEPT; | |
128 | ||
129 | /* Until there's been traffic both ways, don't look in packets. */ | |
fb048833 | 130 | if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) |
869f37d8 PM |
131 | return NF_ACCEPT; |
132 | ||
133 | /* Not a full tcp header? */ | |
3db05fea | 134 | th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); |
869f37d8 PM |
135 | if (th == NULL) |
136 | return NF_ACCEPT; | |
137 | ||
138 | /* No data? */ | |
139 | dataoff = protoff + th->doff*4; | |
3db05fea | 140 | if (dataoff >= skb->len) |
869f37d8 PM |
141 | return NF_ACCEPT; |
142 | ||
143 | spin_lock_bh(&irc_buffer_lock); | |
3db05fea | 144 | ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, |
869f37d8 PM |
145 | irc_buffer); |
146 | BUG_ON(ib_ptr == NULL); | |
147 | ||
148 | data = ib_ptr; | |
3db05fea | 149 | data_limit = ib_ptr + skb->len - dataoff; |
869f37d8 PM |
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 | data += 5; | |
159 | /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ | |
160 | ||
3db05fea | 161 | iph = ip_hdr(skb); |
14d5e834 HH |
162 | pr_debug("DCC found in master %pI4:%u %pI4:%u\n", |
163 | &iph->saddr, ntohs(th->source), | |
164 | &iph->daddr, ntohs(th->dest)); | |
869f37d8 PM |
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 | data += strlen(dccprotos[i]); | |
0d53778e | 172 | pr_debug("DCC %s detected\n", dccprotos[i]); |
869f37d8 PM |
173 | |
174 | /* we have at least | |
175 | * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid | |
176 | * data left (== 14/13 bytes) */ | |
58c0fb0d | 177 | if (parse_dcc(data, data_limit, &dcc_ip, |
869f37d8 | 178 | &dcc_port, &addr_beg_p, &addr_end_p)) { |
0d53778e | 179 | pr_debug("unable to parse dcc command\n"); |
869f37d8 PM |
180 | continue; |
181 | } | |
f9409649 HH |
182 | |
183 | pr_debug("DCC bound ip/port: %pI4:%u\n", | |
184 | &dcc_ip, dcc_port); | |
869f37d8 PM |
185 | |
186 | /* dcc_ip can be the internal OR external (NAT'ed) IP */ | |
187 | tuple = &ct->tuplehash[dir].tuple; | |
f9409649 HH |
188 | if (tuple->src.u3.ip != dcc_ip && |
189 | tuple->dst.u3.ip != dcc_ip) { | |
e87cc472 JP |
190 | net_warn_ratelimited("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 | 197 | if (exp == NULL) { |
b20ab9cc PNA |
198 | nf_ct_helper_log(skb, ct, |
199 | "cannot alloc expectation"); | |
869f37d8 PM |
200 | ret = NF_DROP; |
201 | goto out; | |
202 | } | |
203 | tuple = &ct->tuplehash[!dir].tuple; | |
204 | port = htons(dcc_port); | |
6002f266 PM |
205 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
206 | tuple->src.l3num, | |
6823645d PM |
207 | NULL, &tuple->dst.u3, |
208 | IPPROTO_TCP, NULL, &port); | |
869f37d8 PM |
209 | |
210 | nf_nat_irc = rcu_dereference(nf_nat_irc_hook); | |
5901b6be | 211 | if (nf_nat_irc && ct->status & IPS_NAT_MASK) |
051966c0 | 212 | ret = nf_nat_irc(skb, ctinfo, protoff, |
869f37d8 PM |
213 | addr_beg_p - ib_ptr, |
214 | addr_end_p - addr_beg_p, | |
215 | exp); | |
b20ab9cc PNA |
216 | else if (nf_ct_expect_related(exp) != 0) { |
217 | nf_ct_helper_log(skb, ct, | |
218 | "cannot add expectation"); | |
869f37d8 | 219 | ret = NF_DROP; |
b20ab9cc | 220 | } |
6823645d | 221 | nf_ct_expect_put(exp); |
869f37d8 PM |
222 | goto out; |
223 | } | |
224 | } | |
225 | out: | |
226 | spin_unlock_bh(&irc_buffer_lock); | |
227 | return ret; | |
228 | } | |
229 | ||
230 | static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; | |
6002f266 | 231 | static struct nf_conntrack_expect_policy irc_exp_policy; |
869f37d8 PM |
232 | |
233 | static void nf_conntrack_irc_fini(void); | |
234 | ||
235 | static int __init nf_conntrack_irc_init(void) | |
236 | { | |
237 | int i, ret; | |
869f37d8 PM |
238 | |
239 | if (max_dcc_channels < 1) { | |
654d0fbd | 240 | printk(KERN_ERR "nf_ct_irc: max_dcc_channels must not be zero\n"); |
869f37d8 PM |
241 | return -EINVAL; |
242 | } | |
243 | ||
6002f266 PM |
244 | irc_exp_policy.max_expected = max_dcc_channels; |
245 | irc_exp_policy.timeout = dcc_timeout; | |
246 | ||
869f37d8 PM |
247 | irc_buffer = kmalloc(65536, GFP_KERNEL); |
248 | if (!irc_buffer) | |
249 | return -ENOMEM; | |
250 | ||
251 | /* If no port given, default to standard irc port */ | |
252 | if (ports_c == 0) | |
253 | ports[ports_c++] = IRC_PORT; | |
254 | ||
255 | for (i = 0; i < ports_c; i++) { | |
256 | irc[i].tuple.src.l3num = AF_INET; | |
257 | irc[i].tuple.src.u.tcp.port = htons(ports[i]); | |
258 | irc[i].tuple.dst.protonum = IPPROTO_TCP; | |
6002f266 | 259 | irc[i].expect_policy = &irc_exp_policy; |
869f37d8 PM |
260 | irc[i].me = THIS_MODULE; |
261 | irc[i].help = help; | |
262 | ||
869f37d8 | 263 | if (ports[i] == IRC_PORT) |
3a8fc53a | 264 | sprintf(irc[i].name, "irc"); |
869f37d8 | 265 | else |
3a8fc53a | 266 | sprintf(irc[i].name, "irc-%u", i); |
869f37d8 PM |
267 | |
268 | ret = nf_conntrack_helper_register(&irc[i]); | |
269 | if (ret) { | |
654d0fbd | 270 | printk(KERN_ERR "nf_ct_irc: failed to register helper " |
869f37d8 PM |
271 | "for pf: %u port: %u\n", |
272 | irc[i].tuple.src.l3num, ports[i]); | |
273 | nf_conntrack_irc_fini(); | |
274 | return ret; | |
275 | } | |
276 | } | |
277 | return 0; | |
278 | } | |
279 | ||
280 | /* This function is intentionally _NOT_ defined as __exit, because | |
281 | * it is needed by the init function */ | |
282 | static void nf_conntrack_irc_fini(void) | |
283 | { | |
284 | int i; | |
285 | ||
286 | for (i = 0; i < ports_c; i++) | |
287 | nf_conntrack_helper_unregister(&irc[i]); | |
288 | kfree(irc_buffer); | |
289 | } | |
290 | ||
291 | module_init(nf_conntrack_irc_init); | |
292 | module_exit(nf_conntrack_irc_fini); |