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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 | ||
45 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); | |
46 | MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); | |
47 | MODULE_LICENSE("GPL"); | |
48 | MODULE_ALIAS("ip_conntrack_irc"); | |
4dc06f96 | 49 | MODULE_ALIAS_NFCT_HELPER("irc"); |
869f37d8 PM |
50 | |
51 | module_param_array(ports, ushort, &ports_c, 0400); | |
52 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); | |
53 | module_param(max_dcc_channels, uint, 0400); | |
54 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " | |
55 | "IRC session"); | |
56 | module_param(dcc_timeout, uint, 0400); | |
57 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); | |
58 | ||
58c0fb0d | 59 | static const char *const dccprotos[] = { |
869f37d8 PM |
60 | "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " |
61 | }; | |
62 | ||
63 | #define MINMATCHLEN 5 | |
64 | ||
869f37d8 PM |
65 | /* tries to get the ip_addr and port out of a dcc command |
66 | * return value: -1 on failure, 0 on success | |
67 | * data pointer to first byte of DCC command data | |
68 | * data_end pointer to last byte of dcc command data | |
69 | * ip returns parsed ip of dcc command | |
70 | * port returns parsed port of dcc command | |
71 | * ad_beg_p returns pointer to first byte of addr data | |
72 | * ad_end_p returns pointer to last byte of addr data | |
73 | */ | |
f9409649 | 74 | static int parse_dcc(char *data, const char *data_end, __be32 *ip, |
869f37d8 PM |
75 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
76 | { | |
e3b802ba PM |
77 | char *tmp; |
78 | ||
869f37d8 PM |
79 | /* at least 12: "AAAAAAAA P\1\n" */ |
80 | while (*data++ != ' ') | |
81 | if (data > data_end - 12) | |
82 | return -1; | |
83 | ||
e3b802ba PM |
84 | /* Make sure we have a newline character within the packet boundaries |
85 | * because simple_strtoul parses until the first invalid character. */ | |
86 | for (tmp = data; tmp <= data_end; tmp++) | |
87 | if (*tmp == '\n') | |
88 | break; | |
89 | if (tmp > data_end || *tmp != '\n') | |
90 | return -1; | |
91 | ||
869f37d8 | 92 | *ad_beg_p = data; |
f9409649 | 93 | *ip = cpu_to_be32(simple_strtoul(data, &data, 10)); |
869f37d8 PM |
94 | |
95 | /* skip blanks between ip and port */ | |
96 | while (*data == ' ') { | |
97 | if (data >= data_end) | |
98 | return -1; | |
99 | data++; | |
100 | } | |
101 | ||
102 | *port = simple_strtoul(data, &data, 10); | |
103 | *ad_end_p = data; | |
104 | ||
105 | return 0; | |
106 | } | |
107 | ||
3db05fea | 108 | static int help(struct sk_buff *skb, unsigned int protoff, |
869f37d8 PM |
109 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
110 | { | |
111 | unsigned int dataoff; | |
58c0fb0d JE |
112 | const struct iphdr *iph; |
113 | const struct tcphdr *th; | |
114 | struct tcphdr _tcph; | |
115 | const char *data_limit; | |
116 | char *data, *ib_ptr; | |
869f37d8 PM |
117 | int dir = CTINFO2DIR(ctinfo); |
118 | struct nf_conntrack_expect *exp; | |
119 | struct nf_conntrack_tuple *tuple; | |
f9409649 | 120 | __be32 dcc_ip; |
869f37d8 PM |
121 | u_int16_t dcc_port; |
122 | __be16 port; | |
123 | int i, ret = NF_ACCEPT; | |
124 | char *addr_beg_p, *addr_end_p; | |
125 | typeof(nf_nat_irc_hook) nf_nat_irc; | |
126 | ||
127 | /* If packet is coming from IRC server */ | |
128 | if (dir == IP_CT_DIR_REPLY) | |
129 | return NF_ACCEPT; | |
130 | ||
131 | /* Until there's been traffic both ways, don't look in packets. */ | |
fb048833 | 132 | if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) |
869f37d8 PM |
133 | return NF_ACCEPT; |
134 | ||
135 | /* Not a full tcp header? */ | |
3db05fea | 136 | th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); |
869f37d8 PM |
137 | if (th == NULL) |
138 | return NF_ACCEPT; | |
139 | ||
140 | /* No data? */ | |
141 | dataoff = protoff + th->doff*4; | |
3db05fea | 142 | if (dataoff >= skb->len) |
869f37d8 PM |
143 | return NF_ACCEPT; |
144 | ||
145 | spin_lock_bh(&irc_buffer_lock); | |
3db05fea | 146 | ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, |
869f37d8 PM |
147 | irc_buffer); |
148 | BUG_ON(ib_ptr == NULL); | |
149 | ||
150 | data = ib_ptr; | |
3db05fea | 151 | data_limit = ib_ptr + skb->len - dataoff; |
869f37d8 PM |
152 | |
153 | /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24 | |
154 | * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */ | |
155 | while (data < data_limit - (19 + MINMATCHLEN)) { | |
156 | if (memcmp(data, "\1DCC ", 5)) { | |
157 | data++; | |
158 | continue; | |
159 | } | |
160 | data += 5; | |
161 | /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ | |
162 | ||
3db05fea | 163 | iph = ip_hdr(skb); |
14d5e834 HH |
164 | pr_debug("DCC found in master %pI4:%u %pI4:%u\n", |
165 | &iph->saddr, ntohs(th->source), | |
166 | &iph->daddr, ntohs(th->dest)); | |
869f37d8 PM |
167 | |
168 | for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { | |
169 | if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { | |
170 | /* no match */ | |
171 | continue; | |
172 | } | |
173 | data += strlen(dccprotos[i]); | |
0d53778e | 174 | pr_debug("DCC %s detected\n", dccprotos[i]); |
869f37d8 PM |
175 | |
176 | /* we have at least | |
177 | * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid | |
178 | * data left (== 14/13 bytes) */ | |
58c0fb0d | 179 | if (parse_dcc(data, data_limit, &dcc_ip, |
869f37d8 | 180 | &dcc_port, &addr_beg_p, &addr_end_p)) { |
0d53778e | 181 | pr_debug("unable to parse dcc command\n"); |
869f37d8 PM |
182 | continue; |
183 | } | |
f9409649 HH |
184 | |
185 | pr_debug("DCC bound ip/port: %pI4:%u\n", | |
186 | &dcc_ip, dcc_port); | |
869f37d8 PM |
187 | |
188 | /* dcc_ip can be the internal OR external (NAT'ed) IP */ | |
189 | tuple = &ct->tuplehash[dir].tuple; | |
f9409649 HH |
190 | if (tuple->src.u3.ip != dcc_ip && |
191 | tuple->dst.u3.ip != dcc_ip) { | |
e87cc472 JP |
192 | net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n", |
193 | &tuple->src.u3.ip, | |
194 | &dcc_ip, dcc_port); | |
869f37d8 PM |
195 | continue; |
196 | } | |
197 | ||
6823645d | 198 | exp = nf_ct_expect_alloc(ct); |
869f37d8 | 199 | if (exp == NULL) { |
b20ab9cc PNA |
200 | nf_ct_helper_log(skb, ct, |
201 | "cannot alloc expectation"); | |
869f37d8 PM |
202 | ret = NF_DROP; |
203 | goto out; | |
204 | } | |
205 | tuple = &ct->tuplehash[!dir].tuple; | |
206 | port = htons(dcc_port); | |
6002f266 PM |
207 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
208 | tuple->src.l3num, | |
6823645d PM |
209 | NULL, &tuple->dst.u3, |
210 | IPPROTO_TCP, NULL, &port); | |
869f37d8 PM |
211 | |
212 | nf_nat_irc = rcu_dereference(nf_nat_irc_hook); | |
5901b6be | 213 | if (nf_nat_irc && ct->status & IPS_NAT_MASK) |
051966c0 | 214 | ret = nf_nat_irc(skb, ctinfo, protoff, |
869f37d8 PM |
215 | addr_beg_p - ib_ptr, |
216 | addr_end_p - addr_beg_p, | |
217 | exp); | |
b20ab9cc PNA |
218 | else if (nf_ct_expect_related(exp) != 0) { |
219 | nf_ct_helper_log(skb, ct, | |
220 | "cannot add expectation"); | |
869f37d8 | 221 | ret = NF_DROP; |
b20ab9cc | 222 | } |
6823645d | 223 | nf_ct_expect_put(exp); |
869f37d8 PM |
224 | goto out; |
225 | } | |
226 | } | |
227 | out: | |
228 | spin_unlock_bh(&irc_buffer_lock); | |
229 | return ret; | |
230 | } | |
231 | ||
232 | static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; | |
6002f266 | 233 | static struct nf_conntrack_expect_policy irc_exp_policy; |
869f37d8 PM |
234 | |
235 | static void nf_conntrack_irc_fini(void); | |
236 | ||
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 | ||
6002f266 PM |
246 | irc_exp_policy.max_expected = max_dcc_channels; |
247 | irc_exp_policy.timeout = dcc_timeout; | |
248 | ||
869f37d8 PM |
249 | irc_buffer = kmalloc(65536, GFP_KERNEL); |
250 | if (!irc_buffer) | |
251 | return -ENOMEM; | |
252 | ||
253 | /* If no port given, default to standard irc port */ | |
254 | if (ports_c == 0) | |
255 | ports[ports_c++] = IRC_PORT; | |
256 | ||
257 | for (i = 0; i < ports_c; i++) { | |
82de0be6 GF |
258 | nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, "irc", |
259 | IRC_PORT, ports[i], i, &irc_exp_policy, | |
260 | 0, 0, help, NULL, THIS_MODULE); | |
261 | } | |
262 | ||
263 | ret = nf_conntrack_helpers_register(&irc[0], ports_c); | |
264 | if (ret) { | |
265 | pr_err("failed to register helpers\n"); | |
266 | kfree(irc_buffer); | |
267 | return ret; | |
869f37d8 | 268 | } |
82de0be6 | 269 | |
869f37d8 PM |
270 | return 0; |
271 | } | |
272 | ||
273 | /* This function is intentionally _NOT_ defined as __exit, because | |
274 | * it is needed by the init function */ | |
275 | static void nf_conntrack_irc_fini(void) | |
276 | { | |
82de0be6 | 277 | nf_conntrack_helpers_unregister(irc, ports_c); |
869f37d8 PM |
278 | kfree(irc_buffer); |
279 | } | |
280 | ||
281 | module_init(nf_conntrack_irc_init); | |
282 | module_exit(nf_conntrack_irc_fini); |