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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 | * (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 | ||
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 nf_conntrack_expect *exp; | |
92 | struct nf_conntrack_tuple *tuple; | |
93 | unsigned int dataoff, start, stop, off, i; | |
94 | char pbuf[sizeof("65535")], *tmp; | |
95 | u_int16_t len; | |
96 | __be16 port; | |
97 | int ret = NF_ACCEPT; | |
98 | typeof(nf_nat_amanda_hook) nf_nat_amanda; | |
99 | ||
100 | /* Only look at packets from the Amanda server */ | |
101 | if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) | |
102 | return NF_ACCEPT; | |
103 | ||
104 | /* increase the UDP timeout of the master connection as replies from | |
105 | * Amanda clients to the server can be quite delayed */ | |
106 | nf_ct_refresh(ct, skb, master_timeout * HZ); | |
107 | ||
108 | /* No data? */ | |
109 | dataoff = protoff + sizeof(struct udphdr); | |
110 | if (dataoff >= skb->len) { | |
111 | net_err_ratelimited("amanda_help: skblen = %u\n", skb->len); | |
112 | return NF_ACCEPT; | |
113 | } | |
114 | ||
115 | start = skb_find_text(skb, dataoff, skb->len, | |
116 | search[SEARCH_CONNECT].ts); | |
117 | if (start == UINT_MAX) | |
118 | goto out; | |
119 | start += dataoff + search[SEARCH_CONNECT].len; | |
120 | ||
121 | stop = skb_find_text(skb, start, skb->len, | |
122 | search[SEARCH_NEWLINE].ts); | |
123 | if (stop == UINT_MAX) | |
124 | goto out; | |
125 | stop += start; | |
126 | ||
127 | for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) { | |
128 | off = skb_find_text(skb, start, stop, search[i].ts); | |
129 | if (off == UINT_MAX) | |
130 | continue; | |
131 | off += start + search[i].len; | |
132 | ||
133 | len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off); | |
134 | if (skb_copy_bits(skb, off, pbuf, len)) | |
135 | break; | |
136 | pbuf[len] = '\0'; | |
137 | ||
138 | port = htons(simple_strtoul(pbuf, &tmp, 10)); | |
139 | len = tmp - pbuf; | |
140 | if (port == 0 || len > 5) | |
141 | break; | |
142 | ||
143 | exp = nf_ct_expect_alloc(ct); | |
144 | if (exp == NULL) { | |
145 | nf_ct_helper_log(skb, ct, "cannot alloc expectation"); | |
146 | ret = NF_DROP; | |
147 | goto out; | |
148 | } | |
149 | tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; | |
150 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, | |
151 | nf_ct_l3num(ct), | |
152 | &tuple->src.u3, &tuple->dst.u3, | |
153 | IPPROTO_TCP, NULL, &port); | |
154 | ||
155 | nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook); | |
156 | if (nf_nat_amanda && ct->status & IPS_NAT_MASK) | |
157 | ret = nf_nat_amanda(skb, ctinfo, protoff, | |
158 | off - dataoff, len, exp); | |
159 | else if (nf_ct_expect_related(exp) != 0) { | |
160 | nf_ct_helper_log(skb, ct, "cannot add expectation"); | |
161 | ret = NF_DROP; | |
162 | } | |
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 | NF_CT_HELPER_BUILD_BUG_ON(0); | |
211 | ||
212 | for (i = 0; i < ARRAY_SIZE(search); i++) { | |
213 | search[i].ts = textsearch_prepare(ts_algo, search[i].string, | |
214 | search[i].len, | |
215 | GFP_KERNEL, TS_AUTOLOAD); | |
216 | if (IS_ERR(search[i].ts)) { | |
217 | ret = PTR_ERR(search[i].ts); | |
218 | goto err1; | |
219 | } | |
220 | } | |
221 | ret = nf_conntrack_helper_register(&amanda_helper[0]); | |
222 | if (ret < 0) | |
223 | goto err1; | |
224 | ret = nf_conntrack_helper_register(&amanda_helper[1]); | |
225 | if (ret < 0) | |
226 | goto err2; | |
227 | return 0; | |
228 | ||
229 | err2: | |
230 | nf_conntrack_helper_unregister(&amanda_helper[0]); | |
231 | err1: | |
232 | while (--i >= 0) | |
233 | textsearch_destroy(search[i].ts); | |
234 | ||
235 | return ret; | |
236 | } | |
237 | ||
238 | module_init(nf_conntrack_amanda_init); | |
239 | module_exit(nf_conntrack_amanda_fini); |