Commit | Line | Data |
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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 | ||
ad6d9503 PNA |
12 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
13 | ||
869f37d8 PM |
14 | #include <linux/module.h> |
15 | #include <linux/moduleparam.h> | |
16 | #include <linux/skbuff.h> | |
17 | #include <linux/in.h> | |
0d53778e | 18 | #include <linux/ip.h> |
869f37d8 PM |
19 | #include <linux/tcp.h> |
20 | #include <linux/netfilter.h> | |
5a0e3ad6 | 21 | #include <linux/slab.h> |
869f37d8 PM |
22 | |
23 | #include <net/netfilter/nf_conntrack.h> | |
24 | #include <net/netfilter/nf_conntrack_expect.h> | |
25 | #include <net/netfilter/nf_conntrack_helper.h> | |
26 | #include <linux/netfilter/nf_conntrack_irc.h> | |
27 | ||
28 | #define MAX_PORTS 8 | |
29 | static unsigned short ports[MAX_PORTS]; | |
2f0d2f10 | 30 | static unsigned int ports_c; |
869f37d8 PM |
31 | static unsigned int max_dcc_channels = 8; |
32 | static unsigned int dcc_timeout __read_mostly = 300; | |
33 | /* This is slow, but it's simple. --RR */ | |
34 | static char *irc_buffer; | |
35 | static DEFINE_SPINLOCK(irc_buffer_lock); | |
36 | ||
3db05fea | 37 | unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb, |
869f37d8 | 38 | enum ip_conntrack_info ctinfo, |
051966c0 | 39 | unsigned int protoff, |
869f37d8 PM |
40 | unsigned int matchoff, |
41 | unsigned int matchlen, | |
42 | struct nf_conntrack_expect *exp) __read_mostly; | |
43 | EXPORT_SYMBOL_GPL(nf_nat_irc_hook); | |
44 | ||
08010a21 FL |
45 | #define HELPER_NAME "irc" |
46 | ||
869f37d8 PM |
47 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
48 | MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); | |
49 | MODULE_LICENSE("GPL"); | |
50 | MODULE_ALIAS("ip_conntrack_irc"); | |
08010a21 | 51 | MODULE_ALIAS_NFCT_HELPER(HELPER_NAME); |
869f37d8 PM |
52 | |
53 | module_param_array(ports, ushort, &ports_c, 0400); | |
54 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); | |
55 | module_param(max_dcc_channels, uint, 0400); | |
56 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " | |
57 | "IRC session"); | |
58 | module_param(dcc_timeout, uint, 0400); | |
59 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); | |
60 | ||
58c0fb0d | 61 | static const char *const dccprotos[] = { |
869f37d8 PM |
62 | "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " |
63 | }; | |
64 | ||
65 | #define MINMATCHLEN 5 | |
66 | ||
869f37d8 PM |
67 | /* tries to get the ip_addr and port out of a dcc command |
68 | * return value: -1 on failure, 0 on success | |
69 | * data pointer to first byte of DCC command data | |
70 | * data_end pointer to last byte of dcc command data | |
71 | * ip returns parsed ip of dcc command | |
72 | * port returns parsed port of dcc command | |
73 | * ad_beg_p returns pointer to first byte of addr data | |
74 | * ad_end_p returns pointer to last byte of addr data | |
75 | */ | |
f9409649 | 76 | static int parse_dcc(char *data, const char *data_end, __be32 *ip, |
869f37d8 PM |
77 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
78 | { | |
e3b802ba PM |
79 | char *tmp; |
80 | ||
869f37d8 PM |
81 | /* at least 12: "AAAAAAAA P\1\n" */ |
82 | while (*data++ != ' ') | |
83 | if (data > data_end - 12) | |
84 | return -1; | |
85 | ||
e3b802ba PM |
86 | /* Make sure we have a newline character within the packet boundaries |
87 | * because simple_strtoul parses until the first invalid character. */ | |
88 | for (tmp = data; tmp <= data_end; tmp++) | |
89 | if (*tmp == '\n') | |
90 | break; | |
91 | if (tmp > data_end || *tmp != '\n') | |
92 | return -1; | |
93 | ||
869f37d8 | 94 | *ad_beg_p = data; |
f9409649 | 95 | *ip = cpu_to_be32(simple_strtoul(data, &data, 10)); |
869f37d8 PM |
96 | |
97 | /* skip blanks between ip and port */ | |
98 | while (*data == ' ') { | |
99 | if (data >= data_end) | |
100 | return -1; | |
101 | data++; | |
102 | } | |
103 | ||
104 | *port = simple_strtoul(data, &data, 10); | |
105 | *ad_end_p = data; | |
106 | ||
107 | return 0; | |
108 | } | |
109 | ||
3db05fea | 110 | static int help(struct sk_buff *skb, unsigned int protoff, |
869f37d8 PM |
111 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
112 | { | |
113 | unsigned int dataoff; | |
58c0fb0d JE |
114 | const struct iphdr *iph; |
115 | const struct tcphdr *th; | |
116 | struct tcphdr _tcph; | |
117 | const char *data_limit; | |
118 | char *data, *ib_ptr; | |
869f37d8 PM |
119 | int dir = CTINFO2DIR(ctinfo); |
120 | struct nf_conntrack_expect *exp; | |
121 | struct nf_conntrack_tuple *tuple; | |
f9409649 | 122 | __be32 dcc_ip; |
869f37d8 PM |
123 | u_int16_t dcc_port; |
124 | __be16 port; | |
125 | int i, ret = NF_ACCEPT; | |
126 | char *addr_beg_p, *addr_end_p; | |
127 | typeof(nf_nat_irc_hook) nf_nat_irc; | |
128 | ||
129 | /* If packet is coming from IRC server */ | |
130 | if (dir == IP_CT_DIR_REPLY) | |
131 | return NF_ACCEPT; | |
132 | ||
133 | /* Until there's been traffic both ways, don't look in packets. */ | |
fb048833 | 134 | if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) |
869f37d8 PM |
135 | return NF_ACCEPT; |
136 | ||
137 | /* Not a full tcp header? */ | |
3db05fea | 138 | th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); |
869f37d8 PM |
139 | if (th == NULL) |
140 | return NF_ACCEPT; | |
141 | ||
142 | /* No data? */ | |
143 | dataoff = protoff + th->doff*4; | |
3db05fea | 144 | if (dataoff >= skb->len) |
869f37d8 PM |
145 | return NF_ACCEPT; |
146 | ||
147 | spin_lock_bh(&irc_buffer_lock); | |
3db05fea | 148 | ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, |
869f37d8 PM |
149 | irc_buffer); |
150 | BUG_ON(ib_ptr == NULL); | |
151 | ||
152 | data = ib_ptr; | |
3db05fea | 153 | data_limit = ib_ptr + skb->len - dataoff; |
869f37d8 PM |
154 | |
155 | /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24 | |
156 | * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */ | |
157 | while (data < data_limit - (19 + MINMATCHLEN)) { | |
158 | if (memcmp(data, "\1DCC ", 5)) { | |
159 | data++; | |
160 | continue; | |
161 | } | |
162 | data += 5; | |
163 | /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ | |
164 | ||
3db05fea | 165 | iph = ip_hdr(skb); |
14d5e834 HH |
166 | pr_debug("DCC found in master %pI4:%u %pI4:%u\n", |
167 | &iph->saddr, ntohs(th->source), | |
168 | &iph->daddr, ntohs(th->dest)); | |
869f37d8 PM |
169 | |
170 | for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { | |
171 | if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { | |
172 | /* no match */ | |
173 | continue; | |
174 | } | |
175 | data += strlen(dccprotos[i]); | |
0d53778e | 176 | pr_debug("DCC %s detected\n", dccprotos[i]); |
869f37d8 PM |
177 | |
178 | /* we have at least | |
179 | * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid | |
180 | * data left (== 14/13 bytes) */ | |
58c0fb0d | 181 | if (parse_dcc(data, data_limit, &dcc_ip, |
869f37d8 | 182 | &dcc_port, &addr_beg_p, &addr_end_p)) { |
0d53778e | 183 | pr_debug("unable to parse dcc command\n"); |
869f37d8 PM |
184 | continue; |
185 | } | |
f9409649 HH |
186 | |
187 | pr_debug("DCC bound ip/port: %pI4:%u\n", | |
188 | &dcc_ip, dcc_port); | |
869f37d8 PM |
189 | |
190 | /* dcc_ip can be the internal OR external (NAT'ed) IP */ | |
191 | tuple = &ct->tuplehash[dir].tuple; | |
f9409649 HH |
192 | if (tuple->src.u3.ip != dcc_ip && |
193 | tuple->dst.u3.ip != dcc_ip) { | |
e87cc472 JP |
194 | net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n", |
195 | &tuple->src.u3.ip, | |
196 | &dcc_ip, dcc_port); | |
869f37d8 PM |
197 | continue; |
198 | } | |
199 | ||
6823645d | 200 | exp = nf_ct_expect_alloc(ct); |
869f37d8 | 201 | if (exp == NULL) { |
b20ab9cc PNA |
202 | nf_ct_helper_log(skb, ct, |
203 | "cannot alloc expectation"); | |
869f37d8 PM |
204 | ret = NF_DROP; |
205 | goto out; | |
206 | } | |
207 | tuple = &ct->tuplehash[!dir].tuple; | |
208 | port = htons(dcc_port); | |
6002f266 PM |
209 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
210 | tuple->src.l3num, | |
6823645d PM |
211 | NULL, &tuple->dst.u3, |
212 | IPPROTO_TCP, NULL, &port); | |
869f37d8 PM |
213 | |
214 | nf_nat_irc = rcu_dereference(nf_nat_irc_hook); | |
5901b6be | 215 | if (nf_nat_irc && ct->status & IPS_NAT_MASK) |
051966c0 | 216 | ret = nf_nat_irc(skb, ctinfo, protoff, |
869f37d8 PM |
217 | addr_beg_p - ib_ptr, |
218 | addr_end_p - addr_beg_p, | |
219 | exp); | |
b20ab9cc PNA |
220 | else if (nf_ct_expect_related(exp) != 0) { |
221 | nf_ct_helper_log(skb, ct, | |
222 | "cannot add expectation"); | |
869f37d8 | 223 | ret = NF_DROP; |
b20ab9cc | 224 | } |
6823645d | 225 | nf_ct_expect_put(exp); |
869f37d8 PM |
226 | goto out; |
227 | } | |
228 | } | |
229 | out: | |
230 | spin_unlock_bh(&irc_buffer_lock); | |
231 | return ret; | |
232 | } | |
233 | ||
234 | static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; | |
6002f266 | 235 | static struct nf_conntrack_expect_policy irc_exp_policy; |
869f37d8 | 236 | |
869f37d8 PM |
237 | static int __init nf_conntrack_irc_init(void) |
238 | { | |
239 | int i, ret; | |
869f37d8 PM |
240 | |
241 | if (max_dcc_channels < 1) { | |
ad6d9503 | 242 | pr_err("max_dcc_channels must not be zero\n"); |
869f37d8 PM |
243 | return -EINVAL; |
244 | } | |
245 | ||
92f73221 GF |
246 | if (max_dcc_channels > NF_CT_EXPECT_MAX_CNT) { |
247 | pr_err("max_dcc_channels must not be more than %u\n", | |
248 | NF_CT_EXPECT_MAX_CNT); | |
249 | return -EINVAL; | |
250 | } | |
251 | ||
6002f266 PM |
252 | irc_exp_policy.max_expected = max_dcc_channels; |
253 | irc_exp_policy.timeout = dcc_timeout; | |
254 | ||
869f37d8 PM |
255 | irc_buffer = kmalloc(65536, GFP_KERNEL); |
256 | if (!irc_buffer) | |
257 | return -ENOMEM; | |
258 | ||
259 | /* If no port given, default to standard irc port */ | |
260 | if (ports_c == 0) | |
261 | ports[ports_c++] = IRC_PORT; | |
262 | ||
263 | for (i = 0; i < ports_c; i++) { | |
08010a21 | 264 | nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, HELPER_NAME, |
82de0be6 | 265 | IRC_PORT, ports[i], i, &irc_exp_policy, |
9f0f3ebe | 266 | 0, help, NULL, THIS_MODULE); |
82de0be6 GF |
267 | } |
268 | ||
269 | ret = nf_conntrack_helpers_register(&irc[0], ports_c); | |
270 | if (ret) { | |
271 | pr_err("failed to register helpers\n"); | |
272 | kfree(irc_buffer); | |
273 | return ret; | |
869f37d8 | 274 | } |
82de0be6 | 275 | |
869f37d8 PM |
276 | return 0; |
277 | } | |
278 | ||
35341a61 | 279 | static void __exit nf_conntrack_irc_fini(void) |
869f37d8 | 280 | { |
82de0be6 | 281 | nf_conntrack_helpers_unregister(irc, ports_c); |
869f37d8 PM |
282 | kfree(irc_buffer); |
283 | } | |
284 | ||
285 | module_init(nf_conntrack_irc_init); | |
286 | module_exit(nf_conntrack_irc_fini); |