1
2
3
4
5
6
7
8
9
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
27static unsigned int master_timeout __read_mostly = 300;
28static char *ts_algo = "kmp";
29
30MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
31MODULE_DESCRIPTION("Amanda connection tracking module");
32MODULE_LICENSE("GPL");
33MODULE_ALIAS("ip_conntrack_amanda");
34MODULE_ALIAS_NFCT_HELPER("amanda");
35
36module_param(master_timeout, uint, 0600);
37MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
38module_param(ts_algo, charp, 0400);
39MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
40
41unsigned 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;
47EXPORT_SYMBOL_GPL(nf_nat_amanda_hook);
48
49enum amanda_strings {
50 SEARCH_CONNECT,
51 SEARCH_NEWLINE,
52 SEARCH_DATA,
53 SEARCH_MESG,
54 SEARCH_INDEX,
55};
56
57static 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
84static 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
100 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
101 return NF_ACCEPT;
102
103
104
105 nf_ct_refresh(ct, skb, master_timeout * HZ);
106
107
108 dataoff = protoff + sizeof(struct udphdr);
109 if (dataoff >= skb->len) {
110 if (net_ratelimit())
111 printk(KERN_ERR "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
166out:
167 return ret;
168}
169
170static const struct nf_conntrack_expect_policy amanda_exp_policy = {
171 .max_expected = 3,
172 .timeout = 180,
173};
174
175static 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
196static 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
206static 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
227err2:
228 nf_conntrack_helper_unregister(&amanda_helper[0]);
229err1:
230 while (--i >= 0)
231 textsearch_destroy(search[i].ts);
232
233 return ret;
234}
235
236module_init(nf_conntrack_amanda_init);
237module_exit(nf_conntrack_amanda_fini);
238
