← Back to branch summary

~ubuntu-branches/ubuntu/precise/linux-lowlatency/precise

« back to all changes in this revision

Viewing changes to net/netfilter/nf_conntrack_irc.c

  • Committer: Package Import Robot
  • Author(s): Alessio Igor Bogani
  • Date: 2011-10-26 11:13:05 UTC
  • Revision ID: package-import@ubuntu.com-20111026111305-tz023xykf0i6eosh
Tags: upstream-3.2.0
Import upstream version 3.2.0

Show diffs side-by-side

added added

removed removed

Lines of Context:
net/netfilter/nf_conntrack_irc.c
 
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>
 
15
#include <linux/ip.h>
 
16
#include <linux/tcp.h>
 
17
#include <linux/netfilter.h>
 
18
#include <linux/slab.h>
 
19
 
 
20
#include <net/netfilter/nf_conntrack.h>
 
21
#include <net/netfilter/nf_conntrack_expect.h>
 
22
#include <net/netfilter/nf_conntrack_helper.h>
 
23
#include <linux/netfilter/nf_conntrack_irc.h>
 
24
 
 
25
#define MAX_PORTS 8
 
26
static unsigned short ports[MAX_PORTS];
 
27
static unsigned int ports_c;
 
28
static unsigned int max_dcc_channels = 8;
 
29
static unsigned int dcc_timeout __read_mostly = 300;
 
30
/* This is slow, but it's simple. --RR */
 
31
static char *irc_buffer;
 
32
static DEFINE_SPINLOCK(irc_buffer_lock);
 
33
 
 
34
unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
 
35
                                enum ip_conntrack_info ctinfo,
 
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
 
 
41
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
 
42
MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
 
43
MODULE_LICENSE("GPL");
 
44
MODULE_ALIAS("ip_conntrack_irc");
 
45
MODULE_ALIAS_NFCT_HELPER("irc");
 
46
 
 
47
module_param_array(ports, ushort, &ports_c, 0400);
 
48
MODULE_PARM_DESC(ports, "port numbers of IRC servers");
 
49
module_param(max_dcc_channels, uint, 0400);
 
50
MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
 
51
                                   "IRC session");
 
52
module_param(dcc_timeout, uint, 0400);
 
53
MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
 
54
 
 
55
static const char *const dccprotos[] = {
 
56
        "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
 
57
};
 
58
 
 
59
#define MINMATCHLEN     5
 
60
 
 
61
/* tries to get the ip_addr and port out of a dcc command
 
62
 * return value: -1 on failure, 0 on success
 
63
 *      data            pointer to first byte of DCC command data
 
64
 *      data_end        pointer to last byte of dcc command data
 
65
 *      ip              returns parsed ip of dcc command
 
66
 *      port            returns parsed port of dcc command
 
67
 *      ad_beg_p        returns pointer to first byte of addr data
 
68
 *      ad_end_p        returns pointer to last byte of addr data
 
69
 */
 
70
static int parse_dcc(char *data, const char *data_end, __be32 *ip,
 
71
                     u_int16_t *port, char **ad_beg_p, char **ad_end_p)
 
72
{
 
73
        char *tmp;
 
74
 
 
75
        /* at least 12: "AAAAAAAA P\1\n" */
 
76
        while (*data++ != ' ')
 
77
                if (data > data_end - 12)
 
78
                        return -1;
 
79
 
 
80
        /* Make sure we have a newline character within the packet boundaries
 
81
         * because simple_strtoul parses until the first invalid character. */
 
82
        for (tmp = data; tmp <= data_end; tmp++)
 
83
                if (*tmp == '\n')
 
84
                        break;
 
85
        if (tmp > data_end || *tmp != '\n')
 
86
                return -1;
 
87
 
 
88
        *ad_beg_p = data;
 
89
        *ip = cpu_to_be32(simple_strtoul(data, &data, 10));
 
90
 
 
91
        /* skip blanks between ip and port */
 
92
        while (*data == ' ') {
 
93
                if (data >= data_end)
 
94
                        return -1;
 
95
                data++;
 
96
        }
 
97
 
 
98
        *port = simple_strtoul(data, &data, 10);
 
99
        *ad_end_p = data;
 
100
 
 
101
        return 0;
 
102
}
 
103
 
 
104
static int help(struct sk_buff *skb, unsigned int protoff,
 
105
                struct nf_conn *ct, enum ip_conntrack_info ctinfo)
 
106
{
 
107
        unsigned int dataoff;
 
108
        const struct iphdr *iph;
 
109
        const struct tcphdr *th;
 
110
        struct tcphdr _tcph;
 
111
        const char *data_limit;
 
112
        char *data, *ib_ptr;
 
113
        int dir = CTINFO2DIR(ctinfo);
 
114
        struct nf_conntrack_expect *exp;
 
115
        struct nf_conntrack_tuple *tuple;
 
116
        __be32 dcc_ip;
 
117
        u_int16_t dcc_port;
 
118
        __be16 port;
 
119
        int i, ret = NF_ACCEPT;
 
120
        char *addr_beg_p, *addr_end_p;
 
121
        typeof(nf_nat_irc_hook) nf_nat_irc;
 
122
 
 
123
        /* If packet is coming from IRC server */
 
124
        if (dir == IP_CT_DIR_REPLY)
 
125
                return NF_ACCEPT;
 
126
 
 
127
        /* Until there's been traffic both ways, don't look in packets. */
 
128
        if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
 
129
                return NF_ACCEPT;
 
130
 
 
131
        /* Not a full tcp header? */
 
132
        th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
 
133
        if (th == NULL)
 
134
                return NF_ACCEPT;
 
135
 
 
136
        /* No data? */
 
137
        dataoff = protoff + th->doff*4;
 
138
        if (dataoff >= skb->len)
 
139
                return NF_ACCEPT;
 
140
 
 
141
        spin_lock_bh(&irc_buffer_lock);
 
142
        ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
 
143
                                    irc_buffer);
 
144
        BUG_ON(ib_ptr == NULL);
 
145
 
 
146
        data = ib_ptr;
 
147
        data_limit = ib_ptr + skb->len - dataoff;
 
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
 
 
159
                iph = ip_hdr(skb);
 
160
                pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
 
161
                         &iph->saddr, ntohs(th->source),
 
162
                         &iph->daddr, ntohs(th->dest));
 
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]);
 
170
                        pr_debug("DCC %s detected\n", dccprotos[i]);
 
171
 
 
172
                        /* we have at least
 
173
                         * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
 
174
                         * data left (== 14/13 bytes) */
 
175
                        if (parse_dcc(data, data_limit, &dcc_ip,
 
176
                                       &dcc_port, &addr_beg_p, &addr_end_p)) {
 
177
                                pr_debug("unable to parse dcc command\n");
 
178
                                continue;
 
179
                        }
 
180
 
 
181
                        pr_debug("DCC bound ip/port: %pI4:%u\n",
 
182
                                 &dcc_ip, dcc_port);
 
183
 
 
184
                        /* dcc_ip can be the internal OR external (NAT'ed) IP */
 
185
                        tuple = &ct->tuplehash[dir].tuple;
 
186
                        if (tuple->src.u3.ip != dcc_ip &&
 
187
                            tuple->dst.u3.ip != dcc_ip) {
 
188
                                if (net_ratelimit())
 
189
                                        printk(KERN_WARNING
 
190
                                                "Forged DCC command from %pI4: %pI4:%u\n",
 
191
                                                &tuple->src.u3.ip,
 
192
                                                &dcc_ip, dcc_port);
 
193
                                continue;
 
194
                        }
 
195
 
 
196
                        exp = nf_ct_expect_alloc(ct);
 
197
                        if (exp == NULL) {
 
198
                                ret = NF_DROP;
 
199
                                goto out;
 
200
                        }
 
201
                        tuple = &ct->tuplehash[!dir].tuple;
 
202
                        port = htons(dcc_port);
 
203
                        nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
 
204
                                          tuple->src.l3num,
 
205
                                          NULL, &tuple->dst.u3,
 
206
                                          IPPROTO_TCP, NULL, &port);
 
207
 
 
208
                        nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
 
209
                        if (nf_nat_irc && ct->status & IPS_NAT_MASK)
 
210
                                ret = nf_nat_irc(skb, ctinfo,
 
211
                                                 addr_beg_p - ib_ptr,
 
212
                                                 addr_end_p - addr_beg_p,
 
213
                                                 exp);
 
214
                        else if (nf_ct_expect_related(exp) != 0)
 
215
                                ret = NF_DROP;
 
216
                        nf_ct_expect_put(exp);
 
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;
 
227
static struct nf_conntrack_expect_policy irc_exp_policy;
 
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(KERN_ERR "nf_ct_irc: max_dcc_channels must not be zero\n");
 
238
                return -EINVAL;
 
239
        }
 
240
 
 
241
        irc_exp_policy.max_expected = max_dcc_channels;
 
242
        irc_exp_policy.timeout = dcc_timeout;
 
243
 
 
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;
 
256
                irc[i].expect_policy = &irc_exp_policy;
 
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(KERN_ERR "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);