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Linux/net/netfilter/nf_conntrack_amanda.c

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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  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License
  8  * as published by the Free Software Foundation; either version
  9  * 2 of the License, or (at your option) any later version.
 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 
 27 static unsigned int master_timeout __read_mostly = 300;
 28 static char *ts_algo = "kmp";
 29 
 30 MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
 31 MODULE_DESCRIPTION("Amanda connection tracking module");
 32 MODULE_LICENSE("GPL");
 33 MODULE_ALIAS("ip_conntrack_amanda");
 34 MODULE_ALIAS_NFCT_HELPER("amanda");
 35 
 36 module_param(master_timeout, uint, 0600);
 37 MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
 38 module_param(ts_algo, charp, 0400);
 39 MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
 40 
 41 unsigned 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;
 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 };
 56 
 57 static 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 
 84 static 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         /* Only look at packets from the Amanda server */
100         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
101                 return NF_ACCEPT;
102 
103         /* increase the UDP timeout of the master connection as replies from
104          * Amanda clients to the server can be quite delayed */
105         nf_ct_refresh(ct, skb, master_timeout * HZ);
106 
107         /* No data? */
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 
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         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 
227 err2:
228         nf_conntrack_helper_unregister(&amanda_helper[0]);
229 err1:
230         while (--i >= 0)
231                 textsearch_destroy(search[i].ts);
232 
233         return ret;
234 }
235 
236 module_init(nf_conntrack_amanda_init);
237 module_exit(nf_conntrack_amanda_fini);
238 

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