Commit | Line | Data |
---|---|---|
2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
869f37d8 PM |
2 | /* IRC extension for IP connection tracking, Version 1.21 |
3 | * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org> | |
4 | * based on RR's ip_conntrack_ftp.c | |
f229f6ce | 5 | * (C) 2006-2012 Patrick McHardy <kaber@trash.net> |
869f37d8 PM |
6 | */ |
7 | ||
ad6d9503 PNA |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | ||
869f37d8 PM |
10 | #include <linux/module.h> |
11 | #include <linux/moduleparam.h> | |
12 | #include <linux/skbuff.h> | |
13 | #include <linux/in.h> | |
0d53778e | 14 | #include <linux/ip.h> |
869f37d8 PM |
15 | #include <linux/tcp.h> |
16 | #include <linux/netfilter.h> | |
5a0e3ad6 | 17 | #include <linux/slab.h> |
869f37d8 PM |
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 | 34 | enum ip_conntrack_info ctinfo, |
051966c0 | 35 | unsigned int protoff, |
869f37d8 PM |
36 | unsigned int matchoff, |
37 | unsigned int matchlen, | |
38 | struct nf_conntrack_expect *exp) __read_mostly; | |
39 | EXPORT_SYMBOL_GPL(nf_nat_irc_hook); | |
40 | ||
08010a21 | 41 | #define HELPER_NAME "irc" |
976bf59c | 42 | #define MAX_SEARCH_SIZE 4095 |
08010a21 | 43 | |
869f37d8 PM |
44 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
45 | MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); | |
46 | MODULE_LICENSE("GPL"); | |
47 | MODULE_ALIAS("ip_conntrack_irc"); | |
08010a21 | 48 | MODULE_ALIAS_NFCT_HELPER(HELPER_NAME); |
869f37d8 PM |
49 | |
50 | module_param_array(ports, ushort, &ports_c, 0400); | |
51 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); | |
52 | module_param(max_dcc_channels, uint, 0400); | |
53 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " | |
54 | "IRC session"); | |
55 | module_param(dcc_timeout, uint, 0400); | |
56 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); | |
57 | ||
58c0fb0d | 58 | static const char *const dccprotos[] = { |
869f37d8 PM |
59 | "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " |
60 | }; | |
61 | ||
62 | #define MINMATCHLEN 5 | |
63 | ||
869f37d8 PM |
64 | /* tries to get the ip_addr and port out of a dcc command |
65 | * return value: -1 on failure, 0 on success | |
66 | * data pointer to first byte of DCC command data | |
67 | * data_end pointer to last byte of dcc command data | |
68 | * ip returns parsed ip of dcc command | |
69 | * port returns parsed port of dcc command | |
70 | * ad_beg_p returns pointer to first byte of addr data | |
71 | * ad_end_p returns pointer to last byte of addr data | |
72 | */ | |
f9409649 | 73 | static int parse_dcc(char *data, const char *data_end, __be32 *ip, |
869f37d8 PM |
74 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
75 | { | |
e3b802ba PM |
76 | char *tmp; |
77 | ||
869f37d8 PM |
78 | /* at least 12: "AAAAAAAA P\1\n" */ |
79 | while (*data++ != ' ') | |
80 | if (data > data_end - 12) | |
81 | return -1; | |
82 | ||
e3b802ba PM |
83 | /* Make sure we have a newline character within the packet boundaries |
84 | * because simple_strtoul parses until the first invalid character. */ | |
85 | for (tmp = data; tmp <= data_end; tmp++) | |
86 | if (*tmp == '\n') | |
87 | break; | |
88 | if (tmp > data_end || *tmp != '\n') | |
89 | return -1; | |
90 | ||
869f37d8 | 91 | *ad_beg_p = data; |
f9409649 | 92 | *ip = cpu_to_be32(simple_strtoul(data, &data, 10)); |
869f37d8 PM |
93 | |
94 | /* skip blanks between ip and port */ | |
95 | while (*data == ' ') { | |
96 | if (data >= data_end) | |
97 | return -1; | |
98 | data++; | |
99 | } | |
100 | ||
101 | *port = simple_strtoul(data, &data, 10); | |
102 | *ad_end_p = data; | |
103 | ||
104 | return 0; | |
105 | } | |
106 | ||
3db05fea | 107 | static int help(struct sk_buff *skb, unsigned int protoff, |
869f37d8 PM |
108 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
109 | { | |
110 | unsigned int dataoff; | |
58c0fb0d JE |
111 | const struct iphdr *iph; |
112 | const struct tcphdr *th; | |
113 | struct tcphdr _tcph; | |
114 | const char *data_limit; | |
115 | char *data, *ib_ptr; | |
869f37d8 PM |
116 | int dir = CTINFO2DIR(ctinfo); |
117 | struct nf_conntrack_expect *exp; | |
118 | struct nf_conntrack_tuple *tuple; | |
f9409649 | 119 | __be32 dcc_ip; |
869f37d8 PM |
120 | u_int16_t dcc_port; |
121 | __be16 port; | |
122 | int i, ret = NF_ACCEPT; | |
123 | char *addr_beg_p, *addr_end_p; | |
124 | typeof(nf_nat_irc_hook) nf_nat_irc; | |
976bf59c | 125 | unsigned int datalen; |
869f37d8 PM |
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 | ||
976bf59c FW |
145 | datalen = skb->len - dataoff; |
146 | if (datalen > MAX_SEARCH_SIZE) | |
147 | datalen = MAX_SEARCH_SIZE; | |
148 | ||
869f37d8 | 149 | spin_lock_bh(&irc_buffer_lock); |
976bf59c | 150 | ib_ptr = skb_header_pointer(skb, dataoff, datalen, |
869f37d8 | 151 | irc_buffer); |
198ad973 PNA |
152 | if (!ib_ptr) { |
153 | spin_unlock_bh(&irc_buffer_lock); | |
154 | return NF_ACCEPT; | |
155 | } | |
869f37d8 PM |
156 | |
157 | data = ib_ptr; | |
976bf59c | 158 | data_limit = ib_ptr + datalen; |
869f37d8 | 159 | |
e8d5dfd1 DL |
160 | /* Skip any whitespace */ |
161 | while (data < data_limit - 10) { | |
162 | if (*data == ' ' || *data == '\r' || *data == '\n') | |
163 | data++; | |
164 | else | |
165 | break; | |
166 | } | |
167 | ||
168 | /* strlen("PRIVMSG x ")=10 */ | |
169 | if (data < data_limit - 10) { | |
170 | if (strncasecmp("PRIVMSG ", data, 8)) | |
171 | goto out; | |
172 | data += 8; | |
173 | } | |
174 | ||
175 | /* strlen(" :\1DCC SENT t AAAAAAAA P\1\n")=26 | |
176 | * 7+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=26 | |
177 | */ | |
178 | while (data < data_limit - (21 + MINMATCHLEN)) { | |
179 | /* Find first " :", the start of message */ | |
180 | if (memcmp(data, " :", 2)) { | |
869f37d8 PM |
181 | data++; |
182 | continue; | |
183 | } | |
e8d5dfd1 DL |
184 | data += 2; |
185 | ||
186 | /* then check that place only for the DCC command */ | |
187 | if (memcmp(data, "\1DCC ", 5)) | |
188 | goto out; | |
869f37d8 | 189 | data += 5; |
e8d5dfd1 | 190 | /* we have at least (21+MINMATCHLEN)-(2+5) bytes valid data left */ |
869f37d8 | 191 | |
3db05fea | 192 | iph = ip_hdr(skb); |
14d5e834 HH |
193 | pr_debug("DCC found in master %pI4:%u %pI4:%u\n", |
194 | &iph->saddr, ntohs(th->source), | |
195 | &iph->daddr, ntohs(th->dest)); | |
869f37d8 PM |
196 | |
197 | for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { | |
198 | if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { | |
199 | /* no match */ | |
200 | continue; | |
201 | } | |
202 | data += strlen(dccprotos[i]); | |
0d53778e | 203 | pr_debug("DCC %s detected\n", dccprotos[i]); |
869f37d8 PM |
204 | |
205 | /* we have at least | |
e8d5dfd1 | 206 | * (21+MINMATCHLEN)-7-dccprotos[i].matchlen bytes valid |
869f37d8 | 207 | * data left (== 14/13 bytes) */ |
58c0fb0d | 208 | if (parse_dcc(data, data_limit, &dcc_ip, |
869f37d8 | 209 | &dcc_port, &addr_beg_p, &addr_end_p)) { |
0d53778e | 210 | pr_debug("unable to parse dcc command\n"); |
869f37d8 PM |
211 | continue; |
212 | } | |
f9409649 HH |
213 | |
214 | pr_debug("DCC bound ip/port: %pI4:%u\n", | |
215 | &dcc_ip, dcc_port); | |
869f37d8 PM |
216 | |
217 | /* dcc_ip can be the internal OR external (NAT'ed) IP */ | |
218 | tuple = &ct->tuplehash[dir].tuple; | |
0efe125c DL |
219 | if ((tuple->src.u3.ip != dcc_ip && |
220 | ct->tuplehash[!dir].tuple.dst.u3.ip != dcc_ip) || | |
221 | dcc_port == 0) { | |
e87cc472 JP |
222 | net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n", |
223 | &tuple->src.u3.ip, | |
224 | &dcc_ip, dcc_port); | |
869f37d8 PM |
225 | continue; |
226 | } | |
227 | ||
6823645d | 228 | exp = nf_ct_expect_alloc(ct); |
869f37d8 | 229 | if (exp == NULL) { |
b20ab9cc PNA |
230 | nf_ct_helper_log(skb, ct, |
231 | "cannot alloc expectation"); | |
869f37d8 PM |
232 | ret = NF_DROP; |
233 | goto out; | |
234 | } | |
235 | tuple = &ct->tuplehash[!dir].tuple; | |
236 | port = htons(dcc_port); | |
6002f266 PM |
237 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
238 | tuple->src.l3num, | |
6823645d PM |
239 | NULL, &tuple->dst.u3, |
240 | IPPROTO_TCP, NULL, &port); | |
869f37d8 PM |
241 | |
242 | nf_nat_irc = rcu_dereference(nf_nat_irc_hook); | |
5901b6be | 243 | if (nf_nat_irc && ct->status & IPS_NAT_MASK) |
051966c0 | 244 | ret = nf_nat_irc(skb, ctinfo, protoff, |
869f37d8 PM |
245 | addr_beg_p - ib_ptr, |
246 | addr_end_p - addr_beg_p, | |
247 | exp); | |
3c00fb0b | 248 | else if (nf_ct_expect_related(exp, 0) != 0) { |
b20ab9cc PNA |
249 | nf_ct_helper_log(skb, ct, |
250 | "cannot add expectation"); | |
869f37d8 | 251 | ret = NF_DROP; |
b20ab9cc | 252 | } |
6823645d | 253 | nf_ct_expect_put(exp); |
869f37d8 PM |
254 | goto out; |
255 | } | |
256 | } | |
257 | out: | |
258 | spin_unlock_bh(&irc_buffer_lock); | |
259 | return ret; | |
260 | } | |
261 | ||
262 | static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; | |
6002f266 | 263 | static struct nf_conntrack_expect_policy irc_exp_policy; |
869f37d8 | 264 | |
869f37d8 PM |
265 | static int __init nf_conntrack_irc_init(void) |
266 | { | |
267 | int i, ret; | |
869f37d8 PM |
268 | |
269 | if (max_dcc_channels < 1) { | |
ad6d9503 | 270 | pr_err("max_dcc_channels must not be zero\n"); |
869f37d8 PM |
271 | return -EINVAL; |
272 | } | |
273 | ||
92f73221 GF |
274 | if (max_dcc_channels > NF_CT_EXPECT_MAX_CNT) { |
275 | pr_err("max_dcc_channels must not be more than %u\n", | |
276 | NF_CT_EXPECT_MAX_CNT); | |
277 | return -EINVAL; | |
278 | } | |
279 | ||
6002f266 PM |
280 | irc_exp_policy.max_expected = max_dcc_channels; |
281 | irc_exp_policy.timeout = dcc_timeout; | |
282 | ||
976bf59c | 283 | irc_buffer = kmalloc(MAX_SEARCH_SIZE + 1, GFP_KERNEL); |
869f37d8 PM |
284 | if (!irc_buffer) |
285 | return -ENOMEM; | |
286 | ||
287 | /* If no port given, default to standard irc port */ | |
288 | if (ports_c == 0) | |
289 | ports[ports_c++] = IRC_PORT; | |
290 | ||
291 | for (i = 0; i < ports_c; i++) { | |
08010a21 | 292 | nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, HELPER_NAME, |
82de0be6 | 293 | IRC_PORT, ports[i], i, &irc_exp_policy, |
9f0f3ebe | 294 | 0, help, NULL, THIS_MODULE); |
82de0be6 GF |
295 | } |
296 | ||
297 | ret = nf_conntrack_helpers_register(&irc[0], ports_c); | |
298 | if (ret) { | |
299 | pr_err("failed to register helpers\n"); | |
300 | kfree(irc_buffer); | |
301 | return ret; | |
869f37d8 | 302 | } |
82de0be6 | 303 | |
869f37d8 PM |
304 | return 0; |
305 | } | |
306 | ||
35341a61 | 307 | static void __exit nf_conntrack_irc_fini(void) |
869f37d8 | 308 | { |
82de0be6 | 309 | nf_conntrack_helpers_unregister(irc, ports_c); |
869f37d8 PM |
310 | kfree(irc_buffer); |
311 | } | |
312 | ||
313 | module_init(nf_conntrack_irc_init); | |
314 | module_exit(nf_conntrack_irc_fini); |