1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Amanda extension for IP connection tracking
3 *
4 * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
5 * based on HW's ip_conntrack_irc.c as well as other modules
6 * (C) 2006 Patrick McHardy <kaber@trash.net>
7 */
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/moduleparam.h>
11 #include <linux/textsearch.h>
12 #include <linux/skbuff.h>
13 #include <linux/in.h>
14 #include <linux/udp.h>
15 #include <linux/netfilter.h>
16 #include <linux/gfp.h>
17
18 #include <net/netfilter/nf_conntrack.h>
19 #include <net/netfilter/nf_conntrack_expect.h>
20 #include <net/netfilter/nf_conntrack_ecache.h>
21 #include <net/netfilter/nf_conntrack_helper.h>
22 #include <linux/netfilter/nf_conntrack_amanda.h>
23
24 static unsigned int master_timeout __read_mostly = 300;
25 static char *ts_algo = "kmp";
26
27 #define HELPER_NAME "amanda"
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 MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
34
35 module_param(master_timeout, uint, 0600);
36 MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
37 module_param(ts_algo, charp, 0400);
38 MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
39
40 unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
41 enum ip_conntrack_info ctinfo,
42 unsigned int protoff,
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 SEARCH_STATE,
56 };
57
58 static struct {
59 const char *string;
60 size_t len;
61 struct ts_config *ts;
62 } search[] __read_mostly = {
63 [SEARCH_CONNECT] = {
64 .string = "CONNECT ",
65 .len = 8,
66 },
67 [SEARCH_NEWLINE] = {
68 .string = "\n",
69 .len = 1,
70 },
71 [SEARCH_DATA] = {
72 .string = "DATA ",
73 .len = 5,
74 },
75 [SEARCH_MESG] = {
76 .string = "MESG ",
77 .len = 5,
78 },
79 [SEARCH_INDEX] = {
80 .string = "INDEX ",
81 .len = 6,
82 },
83 [SEARCH_STATE] = {
84 .string = "STATE ",
85 .len = 6,
86 },
87 };
88
amanda_help(struct sk_buff * skb,unsigned int protoff,struct nf_conn * ct,enum ip_conntrack_info ctinfo)89 static int amanda_help(struct sk_buff *skb,
90 unsigned int protoff,
91 struct nf_conn *ct,
92 enum ip_conntrack_info ctinfo)
93 {
94 struct nf_conntrack_expect *exp;
95 struct nf_conntrack_tuple *tuple;
96 unsigned int dataoff, start, stop, off, i;
97 char pbuf[sizeof("65535")], *tmp;
98 u_int16_t len;
99 __be16 port;
100 int ret = NF_ACCEPT;
101 typeof(nf_nat_amanda_hook) nf_nat_amanda;
102
103 /* Only look at packets from the Amanda server */
104 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
105 return NF_ACCEPT;
106
107 /* increase the UDP timeout of the master connection as replies from
108 * Amanda clients to the server can be quite delayed */
109 nf_ct_refresh(ct, skb, master_timeout * HZ);
110
111 /* No data? */
112 dataoff = protoff + sizeof(struct udphdr);
113 if (dataoff >= skb->len) {
114 net_err_ratelimited("amanda_help: skblen = %u\n", skb->len);
115 return NF_ACCEPT;
116 }
117
118 start = skb_find_text(skb, dataoff, skb->len,
119 search[SEARCH_CONNECT].ts);
120 if (start == UINT_MAX)
121 goto out;
122 start += dataoff + search[SEARCH_CONNECT].len;
123
124 stop = skb_find_text(skb, start, skb->len,
125 search[SEARCH_NEWLINE].ts);
126 if (stop == UINT_MAX)
127 goto out;
128 stop += start;
129
130 for (i = SEARCH_DATA; i <= SEARCH_STATE; i++) {
131 off = skb_find_text(skb, start, stop, search[i].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 nf_ct_helper_log(skb, ct, "cannot alloc expectation");
149 ret = NF_DROP;
150 goto out;
151 }
152 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
153 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
154 nf_ct_l3num(ct),
155 &tuple->src.u3, &tuple->dst.u3,
156 IPPROTO_TCP, NULL, &port);
157
158 nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook);
159 if (nf_nat_amanda && ct->status & IPS_NAT_MASK)
160 ret = nf_nat_amanda(skb, ctinfo, protoff,
161 off - dataoff, len, exp);
162 else if (nf_ct_expect_related(exp, 0) != 0) {
163 nf_ct_helper_log(skb, ct, "cannot add expectation");
164 ret = NF_DROP;
165 }
166 nf_ct_expect_put(exp);
167 }
168
169 out:
170 return ret;
171 }
172
173 static const struct nf_conntrack_expect_policy amanda_exp_policy = {
174 .max_expected = 4,
175 .timeout = 180,
176 };
177
178 static struct nf_conntrack_helper amanda_helper[2] __read_mostly = {
179 {
180 .name = HELPER_NAME,
181 .me = THIS_MODULE,
182 .help = amanda_help,
183 .tuple.src.l3num = AF_INET,
184 .tuple.src.u.udp.port = cpu_to_be16(10080),
185 .tuple.dst.protonum = IPPROTO_UDP,
186 .expect_policy = &amanda_exp_policy,
187 .nat_mod_name = NF_NAT_HELPER_NAME(HELPER_NAME),
188 },
189 {
190 .name = "amanda",
191 .me = THIS_MODULE,
192 .help = amanda_help,
193 .tuple.src.l3num = AF_INET6,
194 .tuple.src.u.udp.port = cpu_to_be16(10080),
195 .tuple.dst.protonum = IPPROTO_UDP,
196 .expect_policy = &amanda_exp_policy,
197 .nat_mod_name = NF_NAT_HELPER_NAME(HELPER_NAME),
198 },
199 };
200
nf_conntrack_amanda_fini(void)201 static void __exit nf_conntrack_amanda_fini(void)
202 {
203 int i;
204
205 nf_conntrack_helpers_unregister(amanda_helper,
206 ARRAY_SIZE(amanda_helper));
207 for (i = 0; i < ARRAY_SIZE(search); i++)
208 textsearch_destroy(search[i].ts);
209 }
210
nf_conntrack_amanda_init(void)211 static int __init nf_conntrack_amanda_init(void)
212 {
213 int ret, i;
214
215 NF_CT_HELPER_BUILD_BUG_ON(0);
216
217 for (i = 0; i < ARRAY_SIZE(search); i++) {
218 search[i].ts = textsearch_prepare(ts_algo, search[i].string,
219 search[i].len,
220 GFP_KERNEL, TS_AUTOLOAD);
221 if (IS_ERR(search[i].ts)) {
222 ret = PTR_ERR(search[i].ts);
223 goto err1;
224 }
225 }
226 ret = nf_conntrack_helpers_register(amanda_helper,
227 ARRAY_SIZE(amanda_helper));
228 if (ret < 0)
229 goto err1;
230 return 0;
231
232 err1:
233 while (--i >= 0)
234 textsearch_destroy(search[i].ts);
235
236 return ret;
237 }
238
239 module_init(nf_conntrack_amanda_init);
240 module_exit(nf_conntrack_amanda_fini);
241