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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 | * | |
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 | #include <linux/kernel.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/moduleparam.h> | |
14 | #include <linux/textsearch.h> | |
15 | #include <linux/skbuff.h> | |
16 | #include <linux/in.h> | |
17 | #include <linux/udp.h> | |
1863f096 | 18 | #include <linux/netfilter.h> |
16958900 PM |
19 | |
20 | #include <net/netfilter/nf_conntrack.h> | |
21 | #include <net/netfilter/nf_conntrack_expect.h> | |
22 | #include <net/netfilter/nf_conntrack_ecache.h> | |
23 | #include <net/netfilter/nf_conntrack_helper.h> | |
24 | #include <linux/netfilter/nf_conntrack_amanda.h> | |
25 | ||
26 | static unsigned int master_timeout __read_mostly = 300; | |
27 | static char *ts_algo = "kmp"; | |
28 | ||
29 | MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); | |
30 | MODULE_DESCRIPTION("Amanda connection tracking module"); | |
31 | MODULE_LICENSE("GPL"); | |
32 | MODULE_ALIAS("ip_conntrack_amanda"); | |
33 | ||
34 | module_param(master_timeout, uint, 0600); | |
35 | MODULE_PARM_DESC(master_timeout, "timeout for the master connection"); | |
36 | module_param(ts_algo, charp, 0400); | |
37 | MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)"); | |
38 | ||
3db05fea | 39 | unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb, |
16958900 PM |
40 | enum ip_conntrack_info ctinfo, |
41 | unsigned int matchoff, | |
42 | unsigned int matchlen, | |
43 | struct nf_conntrack_expect *exp) | |
44 | __read_mostly; | |
45 | EXPORT_SYMBOL_GPL(nf_nat_amanda_hook); | |
46 | ||
47 | enum amanda_strings { | |
48 | SEARCH_CONNECT, | |
49 | SEARCH_NEWLINE, | |
50 | SEARCH_DATA, | |
51 | SEARCH_MESG, | |
52 | SEARCH_INDEX, | |
53 | }; | |
54 | ||
55 | static struct { | |
58c0fb0d | 56 | const char *string; |
16958900 PM |
57 | size_t len; |
58 | struct ts_config *ts; | |
59 | } search[] __read_mostly = { | |
60 | [SEARCH_CONNECT] = { | |
61 | .string = "CONNECT ", | |
62 | .len = 8, | |
63 | }, | |
64 | [SEARCH_NEWLINE] = { | |
65 | .string = "\n", | |
66 | .len = 1, | |
67 | }, | |
68 | [SEARCH_DATA] = { | |
69 | .string = "DATA ", | |
70 | .len = 5, | |
71 | }, | |
72 | [SEARCH_MESG] = { | |
73 | .string = "MESG ", | |
74 | .len = 5, | |
75 | }, | |
76 | [SEARCH_INDEX] = { | |
77 | .string = "INDEX ", | |
78 | .len = 6, | |
79 | }, | |
80 | }; | |
81 | ||
3db05fea | 82 | static int amanda_help(struct sk_buff *skb, |
16958900 PM |
83 | unsigned int protoff, |
84 | struct nf_conn *ct, | |
85 | enum ip_conntrack_info ctinfo) | |
86 | { | |
87 | struct ts_state ts; | |
88 | struct nf_conntrack_expect *exp; | |
89 | struct nf_conntrack_tuple *tuple; | |
90 | unsigned int dataoff, start, stop, off, i; | |
91 | char pbuf[sizeof("65535")], *tmp; | |
92 | u_int16_t len; | |
93 | __be16 port; | |
16958900 PM |
94 | int ret = NF_ACCEPT; |
95 | typeof(nf_nat_amanda_hook) nf_nat_amanda; | |
96 | ||
97 | /* Only look at packets from the Amanda server */ | |
98 | if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) | |
99 | return NF_ACCEPT; | |
100 | ||
101 | /* increase the UDP timeout of the master connection as replies from | |
102 | * Amanda clients to the server can be quite delayed */ | |
3db05fea | 103 | nf_ct_refresh(ct, skb, master_timeout * HZ); |
16958900 PM |
104 | |
105 | /* No data? */ | |
106 | dataoff = protoff + sizeof(struct udphdr); | |
3db05fea | 107 | if (dataoff >= skb->len) { |
16958900 | 108 | if (net_ratelimit()) |
3db05fea | 109 | printk("amanda_help: skblen = %u\n", skb->len); |
16958900 PM |
110 | return NF_ACCEPT; |
111 | } | |
112 | ||
113 | memset(&ts, 0, sizeof(ts)); | |
3db05fea | 114 | start = skb_find_text(skb, dataoff, skb->len, |
16958900 PM |
115 | search[SEARCH_CONNECT].ts, &ts); |
116 | if (start == UINT_MAX) | |
117 | goto out; | |
118 | start += dataoff + search[SEARCH_CONNECT].len; | |
119 | ||
120 | memset(&ts, 0, sizeof(ts)); | |
3db05fea | 121 | stop = skb_find_text(skb, start, skb->len, |
16958900 PM |
122 | search[SEARCH_NEWLINE].ts, &ts); |
123 | if (stop == UINT_MAX) | |
124 | goto out; | |
125 | stop += start; | |
126 | ||
127 | for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) { | |
128 | memset(&ts, 0, sizeof(ts)); | |
3db05fea | 129 | off = skb_find_text(skb, start, stop, search[i].ts, &ts); |
16958900 PM |
130 | if (off == UINT_MAX) |
131 | continue; | |
132 | off += start + search[i].len; | |
133 | ||
134 | len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off); | |
3db05fea | 135 | if (skb_copy_bits(skb, off, pbuf, len)) |
16958900 PM |
136 | break; |
137 | pbuf[len] = '\0'; | |
138 | ||
139 | port = htons(simple_strtoul(pbuf, &tmp, 10)); | |
140 | len = tmp - pbuf; | |
141 | if (port == 0 || len > 5) | |
142 | break; | |
143 | ||
6823645d | 144 | exp = nf_ct_expect_alloc(ct); |
16958900 PM |
145 | if (exp == NULL) { |
146 | ret = NF_DROP; | |
147 | goto out; | |
148 | } | |
149 | tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; | |
5e8fbe2a PM |
150 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
151 | nf_ct_l3num(ct), | |
6002f266 | 152 | &tuple->src.u3, &tuple->dst.u3, |
6823645d | 153 | IPPROTO_TCP, NULL, &port); |
16958900 PM |
154 | |
155 | nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook); | |
156 | if (nf_nat_amanda && ct->status & IPS_NAT_MASK) | |
3db05fea | 157 | ret = nf_nat_amanda(skb, ctinfo, off - dataoff, |
16958900 | 158 | len, exp); |
6823645d | 159 | else if (nf_ct_expect_related(exp) != 0) |
16958900 | 160 | ret = NF_DROP; |
6823645d | 161 | nf_ct_expect_put(exp); |
16958900 PM |
162 | } |
163 | ||
164 | out: | |
165 | return ret; | |
166 | } | |
167 | ||
6002f266 PM |
168 | static const struct nf_conntrack_expect_policy amanda_exp_policy = { |
169 | .max_expected = 3, | |
170 | .timeout = 180, | |
171 | }; | |
172 | ||
16958900 PM |
173 | static struct nf_conntrack_helper amanda_helper[2] __read_mostly = { |
174 | { | |
175 | .name = "amanda", | |
16958900 PM |
176 | .me = THIS_MODULE, |
177 | .help = amanda_help, | |
178 | .tuple.src.l3num = AF_INET, | |
179 | .tuple.src.u.udp.port = __constant_htons(10080), | |
180 | .tuple.dst.protonum = IPPROTO_UDP, | |
6002f266 | 181 | .expect_policy = &amanda_exp_policy, |
16958900 PM |
182 | }, |
183 | { | |
184 | .name = "amanda", | |
16958900 PM |
185 | .me = THIS_MODULE, |
186 | .help = amanda_help, | |
187 | .tuple.src.l3num = AF_INET6, | |
188 | .tuple.src.u.udp.port = __constant_htons(10080), | |
189 | .tuple.dst.protonum = IPPROTO_UDP, | |
6002f266 | 190 | .expect_policy = &amanda_exp_policy, |
16958900 PM |
191 | }, |
192 | }; | |
193 | ||
194 | static void __exit nf_conntrack_amanda_fini(void) | |
195 | { | |
196 | int i; | |
197 | ||
198 | nf_conntrack_helper_unregister(&amanda_helper[0]); | |
199 | nf_conntrack_helper_unregister(&amanda_helper[1]); | |
200 | for (i = 0; i < ARRAY_SIZE(search); i++) | |
201 | textsearch_destroy(search[i].ts); | |
202 | } | |
203 | ||
204 | static int __init nf_conntrack_amanda_init(void) | |
205 | { | |
206 | int ret, i; | |
207 | ||
16958900 PM |
208 | for (i = 0; i < ARRAY_SIZE(search); i++) { |
209 | search[i].ts = textsearch_prepare(ts_algo, search[i].string, | |
210 | search[i].len, | |
211 | GFP_KERNEL, TS_AUTOLOAD); | |
c764c9ad AM |
212 | if (IS_ERR(search[i].ts)) { |
213 | ret = PTR_ERR(search[i].ts); | |
16958900 | 214 | goto err1; |
c764c9ad | 215 | } |
16958900 PM |
216 | } |
217 | ret = nf_conntrack_helper_register(&amanda_helper[0]); | |
218 | if (ret < 0) | |
219 | goto err1; | |
220 | ret = nf_conntrack_helper_register(&amanda_helper[1]); | |
221 | if (ret < 0) | |
222 | goto err2; | |
223 | return 0; | |
224 | ||
225 | err2: | |
226 | nf_conntrack_helper_unregister(&amanda_helper[0]); | |
227 | err1: | |
c764c9ad AM |
228 | while (--i >= 0) |
229 | textsearch_destroy(search[i].ts); | |
230 | ||
16958900 PM |
231 | return ret; |
232 | } | |
233 | ||
234 | module_init(nf_conntrack_amanda_init); | |
235 | module_exit(nf_conntrack_amanda_fini); |