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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> |
18 | #include <linux/netfilter.h> |
19 | #include <linux/gfp.h> |
20 | |
21 | #include <net/netfilter/nf_conntrack.h> |
22 | #include <net/netfilter/nf_conntrack_expect.h> |
23 | #include <net/netfilter/nf_conntrack_ecache.h> |
24 | #include <net/netfilter/nf_conntrack_helper.h> |
25 | #include <linux/netfilter/nf_conntrack_amanda.h> |
26 | |
27 | static unsigned int master_timeout __read_mostly = 300; |
28 | static char *ts_algo = "kmp"; |
29 | |
30 | MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); |
31 | MODULE_DESCRIPTION("Amanda connection tracking module"); |
32 | MODULE_LICENSE("GPL"); |
33 | MODULE_ALIAS("ip_conntrack_amanda"); |
34 | MODULE_ALIAS_NFCT_HELPER("amanda"); |
35 | |
36 | module_param(master_timeout, uint, 0600); |
37 | MODULE_PARM_DESC(master_timeout, "timeout for the master connection"); |
38 | module_param(ts_algo, charp, 0400); |
39 | MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)"); |
40 | |
41 | unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb, |
42 | enum ip_conntrack_info ctinfo, |
43 | unsigned int matchoff, |
44 | unsigned int matchlen, |
45 | struct nf_conntrack_expect *exp) |
46 | __read_mostly; |
47 | EXPORT_SYMBOL_GPL(nf_nat_amanda_hook); |
48 | |
49 | enum amanda_strings { |
50 | SEARCH_CONNECT, |
51 | SEARCH_NEWLINE, |
52 | SEARCH_DATA, |
53 | SEARCH_MESG, |
54 | SEARCH_INDEX, |
55 | }; |
56 | |
57 | static struct { |
58 | const char *string; |
59 | size_t len; |
60 | struct ts_config *ts; |
61 | } search[] __read_mostly = { |
62 | [SEARCH_CONNECT] = { |
63 | .string = "CONNECT ", |
64 | .len = 8, |
65 | }, |
66 | [SEARCH_NEWLINE] = { |
67 | .string = "\n", |
68 | .len = 1, |
69 | }, |
70 | [SEARCH_DATA] = { |
71 | .string = "DATA ", |
72 | .len = 5, |
73 | }, |
74 | [SEARCH_MESG] = { |
75 | .string = "MESG ", |
76 | .len = 5, |
77 | }, |
78 | [SEARCH_INDEX] = { |
79 | .string = "INDEX ", |
80 | .len = 6, |
81 | }, |
82 | }; |
83 | |
84 | static int amanda_help(struct sk_buff *skb, |
85 | unsigned int protoff, |
86 | struct nf_conn *ct, |
87 | enum ip_conntrack_info ctinfo) |
88 | { |
89 | struct ts_state ts; |
90 | struct nf_conntrack_expect *exp; |
91 | struct nf_conntrack_tuple *tuple; |
92 | unsigned int dataoff, start, stop, off, i; |
93 | char pbuf[sizeof("65535")], *tmp; |
94 | u_int16_t len; |
95 | __be16 port; |
96 | int ret = NF_ACCEPT; |
97 | typeof(nf_nat_amanda_hook) nf_nat_amanda; |
98 | |
99 | /* Only look at packets from the Amanda server */ |
100 | if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) |
101 | return NF_ACCEPT; |
102 | |
103 | /* increase the UDP timeout of the master connection as replies from |
104 | * Amanda clients to the server can be quite delayed */ |
105 | nf_ct_refresh(ct, skb, master_timeout * HZ); |
106 | |
107 | /* No data? */ |
108 | dataoff = protoff + sizeof(struct udphdr); |
109 | if (dataoff >= skb->len) { |
110 | if (net_ratelimit()) |
111 | printk("amanda_help: skblen = %u\n", skb->len); |
112 | return NF_ACCEPT; |
113 | } |
114 | |
115 | memset(&ts, 0, sizeof(ts)); |
116 | start = skb_find_text(skb, dataoff, skb->len, |
117 | search[SEARCH_CONNECT].ts, &ts); |
118 | if (start == UINT_MAX) |
119 | goto out; |
120 | start += dataoff + search[SEARCH_CONNECT].len; |
121 | |
122 | memset(&ts, 0, sizeof(ts)); |
123 | stop = skb_find_text(skb, start, skb->len, |
124 | search[SEARCH_NEWLINE].ts, &ts); |
125 | if (stop == UINT_MAX) |
126 | goto out; |
127 | stop += start; |
128 | |
129 | for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) { |
130 | memset(&ts, 0, sizeof(ts)); |
131 | off = skb_find_text(skb, start, stop, search[i].ts, &ts); |
132 | if (off == UINT_MAX) |
133 | continue; |
134 | off += start + search[i].len; |
135 | |
136 | len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off); |
137 | if (skb_copy_bits(skb, off, pbuf, len)) |
138 | break; |
139 | pbuf[len] = '\0'; |
140 | |
141 | port = htons(simple_strtoul(pbuf, &tmp, 10)); |
142 | len = tmp - pbuf; |
143 | if (port == 0 || len > 5) |
144 | break; |
145 | |
146 | exp = nf_ct_expect_alloc(ct); |
147 | if (exp == NULL) { |
148 | ret = NF_DROP; |
149 | goto out; |
150 | } |
151 | tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; |
152 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
153 | nf_ct_l3num(ct), |
154 | &tuple->src.u3, &tuple->dst.u3, |
155 | IPPROTO_TCP, NULL, &port); |
156 | |
157 | nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook); |
158 | if (nf_nat_amanda && ct->status & IPS_NAT_MASK) |
159 | ret = nf_nat_amanda(skb, ctinfo, off - dataoff, |
160 | len, exp); |
161 | else if (nf_ct_expect_related(exp) != 0) |
162 | ret = NF_DROP; |
163 | nf_ct_expect_put(exp); |
164 | } |
165 | |
166 | out: |
167 | return ret; |
168 | } |
169 | |
170 | static const struct nf_conntrack_expect_policy amanda_exp_policy = { |
171 | .max_expected = 3, |
172 | .timeout = 180, |
173 | }; |
174 | |
175 | static struct nf_conntrack_helper amanda_helper[2] __read_mostly = { |
176 | { |
177 | .name = "amanda", |
178 | .me = THIS_MODULE, |
179 | .help = amanda_help, |
180 | .tuple.src.l3num = AF_INET, |
181 | .tuple.src.u.udp.port = cpu_to_be16(10080), |
182 | .tuple.dst.protonum = IPPROTO_UDP, |
183 | .expect_policy = &amanda_exp_policy, |
184 | }, |
185 | { |
186 | .name = "amanda", |
187 | .me = THIS_MODULE, |
188 | .help = amanda_help, |
189 | .tuple.src.l3num = AF_INET6, |
190 | .tuple.src.u.udp.port = cpu_to_be16(10080), |
191 | .tuple.dst.protonum = IPPROTO_UDP, |
192 | .expect_policy = &amanda_exp_policy, |
193 | }, |
194 | }; |
195 | |
196 | static void __exit nf_conntrack_amanda_fini(void) |
197 | { |
198 | int i; |
199 | |
200 | nf_conntrack_helper_unregister(&amanda_helper[0]); |
201 | nf_conntrack_helper_unregister(&amanda_helper[1]); |
202 | for (i = 0; i < ARRAY_SIZE(search); i++) |
203 | textsearch_destroy(search[i].ts); |
204 | } |
205 | |
206 | static int __init nf_conntrack_amanda_init(void) |
207 | { |
208 | int ret, i; |
209 | |
210 | for (i = 0; i < ARRAY_SIZE(search); i++) { |
211 | search[i].ts = textsearch_prepare(ts_algo, search[i].string, |
212 | search[i].len, |
213 | GFP_KERNEL, TS_AUTOLOAD); |
214 | if (IS_ERR(search[i].ts)) { |
215 | ret = PTR_ERR(search[i].ts); |
216 | goto err1; |
217 | } |
218 | } |
219 | ret = nf_conntrack_helper_register(&amanda_helper[0]); |
220 | if (ret < 0) |
221 | goto err1; |
222 | ret = nf_conntrack_helper_register(&amanda_helper[1]); |
223 | if (ret < 0) |
224 | goto err2; |
225 | return 0; |
226 | |
227 | err2: |
228 | nf_conntrack_helper_unregister(&amanda_helper[0]); |
229 | err1: |
230 | while (--i >= 0) |
231 | textsearch_destroy(search[i].ts); |
232 | |
233 | return ret; |
234 | } |
235 | |
236 | module_init(nf_conntrack_amanda_init); |
237 | module_exit(nf_conntrack_amanda_fini); |
238 |
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