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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
28static unsigned int master_timeout __read_mostly = 300;
29static char *ts_algo = "kmp";
30
31MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
32MODULE_DESCRIPTION("Amanda connection tracking module");
33MODULE_LICENSE("GPL");
34MODULE_ALIAS("ip_conntrack_amanda");
35MODULE_ALIAS_NFCT_HELPER("amanda");
36
37module_param(master_timeout, uint, 0600);
38MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
39module_param(ts_algo, charp, 0400);
40MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
41
42unsigned 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;
49EXPORT_SYMBOL_GPL(nf_nat_amanda_hook);
50
51enum amanda_strings {
52 SEARCH_CONNECT,
53 SEARCH_NEWLINE,
54 SEARCH_DATA,
55 SEARCH_MESG,
56 SEARCH_INDEX,
57};
58
59static 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
86static 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
101 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
102 return NF_ACCEPT;
103
104
105
106 nf_ct_refresh(ct, skb, master_timeout * HZ);
107
108
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
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_helpers_unregister(amanda_helper,
201 ARRAY_SIZE(amanda_helper));
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 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_helpers_register(amanda_helper,
222 ARRAY_SIZE(amanda_helper));
223 if (ret < 0)
224 goto err1;
225 return 0;
226
227err1:
228 while (--i >= 0)
229 textsearch_destroy(search[i].ts);
230
231 return ret;
232}
233
234module_init(nf_conntrack_amanda_init);
235module_exit(nf_conntrack_amanda_fini);
236
