1 /* Amanda extension for IP connection tracking
2 *
3 * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
4 * based on HW's ip_conntrack_irc.c as well as other modules
5 * (C) 2006 Patrick McHardy <kaber@trash.net>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/moduleparam.h>
15 #include <linux/textsearch.h>
16 #include <linux/skbuff.h>
17 #include <linux/in.h>
18 #include <linux/udp.h>
19 #include <linux/netfilter.h>
20 #include <linux/gfp.h>
21
22 #include <net/netfilter/nf_conntrack.h>
23 #include <net/netfilter/nf_conntrack_expect.h>
24 #include <net/netfilter/nf_conntrack_ecache.h>
25 #include <net/netfilter/nf_conntrack_helper.h>
26 #include <linux/netfilter/nf_conntrack_amanda.h>
27
28 static unsigned int master_timeout __read_mostly = 300;
29 static char *ts_algo = "kmp";
30
31 MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
32 MODULE_DESCRIPTION("Amanda connection tracking module");
33 MODULE_LICENSE("GPL");
34 MODULE_ALIAS("ip_conntrack_amanda");
35 MODULE_ALIAS_NFCT_HELPER("amanda");
36
37 module_param(master_timeout, uint, 0600);
38 MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
39 module_param(ts_algo, charp, 0400);
40 MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
41
42 unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
43 enum ip_conntrack_info ctinfo,
44 unsigned int protoff,
45 unsigned int matchoff,
46 unsigned int matchlen,
47 struct nf_conntrack_expect *exp)
48 __read_mostly;
49 EXPORT_SYMBOL_GPL(nf_nat_amanda_hook);
50
51 enum amanda_strings {
52 SEARCH_CONNECT,
53 SEARCH_NEWLINE,
54 SEARCH_DATA,
55 SEARCH_MESG,
56 SEARCH_INDEX,
57 };
58
59 static struct {
60 const char *string;
61 size_t len;
62 struct ts_config *ts;
63 } search[] __read_mostly = {
64 [SEARCH_CONNECT] = {
65 .string = "CONNECT ",
66 .len = 8,
67 },
68 [SEARCH_NEWLINE] = {
69 .string = "\n",
70 .len = 1,
71 },
72 [SEARCH_DATA] = {
73 .string = "DATA ",
74 .len = 5,
75 },
76 [SEARCH_MESG] = {
77 .string = "MESG ",
78 .len = 5,
79 },
80 [SEARCH_INDEX] = {
81 .string = "INDEX ",
82 .len = 6,
83 },
84 };
85
amanda_help(struct sk_buff * skb,unsigned int protoff,struct nf_conn * ct,enum ip_conntrack_info ctinfo)86 static int amanda_help(struct sk_buff *skb,
87 unsigned int protoff,
88 struct nf_conn *ct,
89 enum ip_conntrack_info ctinfo)
90 {
91 struct ts_state ts;
92 struct nf_conntrack_expect *exp;
93 struct nf_conntrack_tuple *tuple;
94 unsigned int dataoff, start, stop, off, i;
95 char pbuf[sizeof("65535")], *tmp;
96 u_int16_t len;
97 __be16 port;
98 int ret = NF_ACCEPT;
99 typeof(nf_nat_amanda_hook) nf_nat_amanda;
100
101 /* Only look at packets from the Amanda server */
102 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
103 return NF_ACCEPT;
104
105 /* increase the UDP timeout of the master connection as replies from
106 * Amanda clients to the server can be quite delayed */
107 nf_ct_refresh(ct, skb, master_timeout * HZ);
108
109 /* No data? */
110 dataoff = protoff + sizeof(struct udphdr);
111 if (dataoff >= skb->len) {
112 net_err_ratelimited("amanda_help: skblen = %u\n", skb->len);
113 return NF_ACCEPT;
114 }
115
116 memset(&ts, 0, sizeof(ts));
117 start = skb_find_text(skb, dataoff, skb->len,
118 search[SEARCH_CONNECT].ts, &ts);
119 if (start == UINT_MAX)
120 goto out;
121 start += dataoff + search[SEARCH_CONNECT].len;
122
123 memset(&ts, 0, sizeof(ts));
124 stop = skb_find_text(skb, start, skb->len,
125 search[SEARCH_NEWLINE].ts, &ts);
126 if (stop == UINT_MAX)
127 goto out;
128 stop += start;
129
130 for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) {
131 memset(&ts, 0, sizeof(ts));
132 off = skb_find_text(skb, start, stop, search[i].ts, &ts);
133 if (off == UINT_MAX)
134 continue;
135 off += start + search[i].len;
136
137 len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off);
138 if (skb_copy_bits(skb, off, pbuf, len))
139 break;
140 pbuf[len] = '\0';
141
142 port = htons(simple_strtoul(pbuf, &tmp, 10));
143 len = tmp - pbuf;
144 if (port == 0 || len > 5)
145 break;
146
147 exp = nf_ct_expect_alloc(ct);
148 if (exp == NULL) {
149 nf_ct_helper_log(skb, ct, "cannot alloc expectation");
150 ret = NF_DROP;
151 goto out;
152 }
153 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
154 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
155 nf_ct_l3num(ct),
156 &tuple->src.u3, &tuple->dst.u3,
157 IPPROTO_TCP, NULL, &port);
158
159 nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook);
160 if (nf_nat_amanda && ct->status & IPS_NAT_MASK)
161 ret = nf_nat_amanda(skb, ctinfo, protoff,
162 off - dataoff, len, exp);
163 else if (nf_ct_expect_related(exp) != 0) {
164 nf_ct_helper_log(skb, ct, "cannot add expectation");
165 ret = NF_DROP;
166 }
167 nf_ct_expect_put(exp);
168 }
169
170 out:
171 return ret;
172 }
173
174 static const struct nf_conntrack_expect_policy amanda_exp_policy = {
175 .max_expected = 3,
176 .timeout = 180,
177 };
178
179 static struct nf_conntrack_helper amanda_helper[2] __read_mostly = {
180 {
181 .name = "amanda",
182 .me = THIS_MODULE,
183 .help = amanda_help,
184 .tuple.src.l3num = AF_INET,
185 .tuple.src.u.udp.port = cpu_to_be16(10080),
186 .tuple.dst.protonum = IPPROTO_UDP,
187 .expect_policy = &amanda_exp_policy,
188 },
189 {
190 .name = "amanda",
191 .me = THIS_MODULE,
192 .help = amanda_help,
193 .tuple.src.l3num = AF_INET6,
194 .tuple.src.u.udp.port = cpu_to_be16(10080),
195 .tuple.dst.protonum = IPPROTO_UDP,
196 .expect_policy = &amanda_exp_policy,
197 },
198 };
199
nf_conntrack_amanda_fini(void)200 static void __exit nf_conntrack_amanda_fini(void)
201 {
202 int i;
203
204 nf_conntrack_helper_unregister(&amanda_helper[0]);
205 nf_conntrack_helper_unregister(&amanda_helper[1]);
206 for (i = 0; i < ARRAY_SIZE(search); i++)
207 textsearch_destroy(search[i].ts);
208 }
209
nf_conntrack_amanda_init(void)210 static int __init nf_conntrack_amanda_init(void)
211 {
212 int ret, i;
213
214 for (i = 0; i < ARRAY_SIZE(search); i++) {
215 search[i].ts = textsearch_prepare(ts_algo, search[i].string,
216 search[i].len,
217 GFP_KERNEL, TS_AUTOLOAD);
218 if (IS_ERR(search[i].ts)) {
219 ret = PTR_ERR(search[i].ts);
220 goto err1;
221 }
222 }
223 ret = nf_conntrack_helper_register(&amanda_helper[0]);
224 if (ret < 0)
225 goto err1;
226 ret = nf_conntrack_helper_register(&amanda_helper[1]);
227 if (ret < 0)
228 goto err2;
229 return 0;
230
231 err2:
232 nf_conntrack_helper_unregister(&amanda_helper[0]);
233 err1:
234 while (--i >= 0)
235 textsearch_destroy(search[i].ts);
236
237 return ret;
238 }
239
240 module_init(nf_conntrack_amanda_init);
241 module_exit(nf_conntrack_amanda_fini);
242