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 | |
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, extra_jiffies: 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, from: dataoff, to: skb->len, |
119 | config: 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, from: start, to: skb->len, |
125 | config: 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, from: start, to: stop, config: 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, offset: off, to: 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(me: ct); |
147 | if (exp == NULL) { |
148 | nf_ct_helper_log(skb, ct, fmt: "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(expect: exp, flags: 0) != 0) { |
163 | nf_ct_helper_log(skb, ct, fmt: "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 | |
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(conf: search[i].ts); |
209 | } |
210 | |
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(ptr: search[i].ts)) { |
222 | ret = PTR_ERR(ptr: 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(conf: search[i].ts); |
235 | |
236 | return ret; |
237 | } |
238 | |
239 | module_init(nf_conntrack_amanda_init); |
240 | module_exit(nf_conntrack_amanda_fini); |
241 | |