net/ipv4/netfilter/ip_conntrack_amanda.c

   1 /* Amanda extension for IP connection tracking, Version 0.2
   2  * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
   3  * based on HW's ip_conntrack_irc.c as well as other modules
   4  *
   5  *      This program is free software; you can redistribute it and/or
   6  *      modify it under the terms of the GNU General Public License
   7  *      as published by the Free Software Foundation; either version
   8  *      2 of the License, or (at your option) any later version.
   9  *
  10  *      Module load syntax:
  11  *      insmod ip_conntrack_amanda.o [master_timeout=n]
  12  *
  13  *      Where master_timeout is the timeout (in seconds) of the master
  14  *      connection (port 10080).  This defaults to 5 minutes but if
  15  *      your clients take longer than 5 minutes to do their work
  16  *      before getting back to the Amanda server, you can increase
  17  *      this value.
  18  *
  19  */
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/textsearch.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/in.h>
  26 #include <linux/ip.h>
  27 #include <linux/udp.h>
  28
  29 #include <linux/netfilter.h>
  30 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
  31 #include <linux/netfilter_ipv4/ip_conntrack_amanda.h>
  32
  33 static unsigned int master_timeout = 300;
  34 static char *ts_algo = "kmp";
  35
  36 MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
  37 MODULE_DESCRIPTION("Amanda connection tracking module");
  38 MODULE_LICENSE("GPL");
  39 module_param(master_timeout, uint, 0600);
  40 MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
  41 module_param(ts_algo, charp, 0400);
  42 MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
  43
  44 unsigned int (*ip_nat_amanda_hook)(struct sk_buff **pskb,
  45                                    enum ip_conntrack_info ctinfo,
  46                                    unsigned int matchoff,
  47                                    unsigned int matchlen,
  48                                    struct ip_conntrack_expect *exp);
  49 EXPORT_SYMBOL_GPL(ip_nat_amanda_hook);
  50
  51 enum amanda_strings {
  52         SEARCH_CONNECT,
  53         SEARCH_NEWLINE,
  54         SEARCH_DATA,
  55         SEARCH_MESG,
  56         SEARCH_INDEX,
  57 };
  58
  59 static struct {
  60         char                    *string;
  61         size_t                  len;
  62         struct ts_config        *ts;
  63 } search[] = {
  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
  86 static int help(struct sk_buff **pskb,
  87                 struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
  88 {
  89         struct ts_state ts;
  90         struct ip_conntrack_expect *exp;
  91         unsigned int dataoff, start, stop, off, i;
  92         char pbuf[sizeof("65535")], *tmp;
  93         u_int16_t port, len;
  94         int ret = NF_ACCEPT;
  95
  96         /* Only look at packets from the Amanda server */
  97         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
  98                 return NF_ACCEPT;
  99
 100         /* increase the UDP timeout of the master connection as replies from
 101          * Amanda clients to the server can be quite delayed */
 102         ip_ct_refresh(ct, *pskb, master_timeout * HZ);
 103
 104         /* No data? */
 105         dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
 106         if (dataoff >= (*pskb)->len) {
 107                 if (net_ratelimit())
 108                         printk("amanda_help: skblen = %u\n", (*pskb)->len);
 109                 return NF_ACCEPT;
 110         }
 111
 112         memset(&ts, 0, sizeof(ts));
 113         start = skb_find_text(*pskb, dataoff, (*pskb)->len,
 114                               search[SEARCH_CONNECT].ts, &ts);
 115         if (start == UINT_MAX)
 116                 goto out;
 117         start += dataoff + search[SEARCH_CONNECT].len;
 118
 119         memset(&ts, 0, sizeof(ts));
 120         stop = skb_find_text(*pskb, start, (*pskb)->len,
 121                              search[SEARCH_NEWLINE].ts, &ts);
 122         if (stop == UINT_MAX)
 123                 goto out;
 124         stop += start;
 125
 126         for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) {
 127                 memset(&ts, 0, sizeof(ts));
 128                 off = skb_find_text(*pskb, start, stop, search[i].ts, &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(*pskb, off, pbuf, len))
 135                         break;
 136                 pbuf[len] = '\0';
 137
 138                 port = simple_strtoul(pbuf, &tmp, 10);
 139                 len = tmp - pbuf;
 140                 if (port == 0 || len > 5)
 141                         break;
 142
 143                 exp = ip_conntrack_expect_alloc(ct);
 144                 if (exp == NULL) {
 145                         ret = NF_DROP;
 146                         goto out;
 147                 }
 148
 149                 exp->expectfn = NULL;
 150                 exp->flags = 0;
 151
 152                 exp->tuple.src.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
 153                 exp->tuple.src.u.tcp.port = 0;
 154                 exp->tuple.dst.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;
 155                 exp->tuple.dst.protonum = IPPROTO_TCP;
 156                 exp->tuple.dst.u.tcp.port = htons(port);
 157
 158                 exp->mask.src.ip = 0xFFFFFFFF;
 159                 exp->mask.src.u.tcp.port = 0;
 160                 exp->mask.dst.ip = 0xFFFFFFFF;
 161                 exp->mask.dst.protonum = 0xFF;
 162                 exp->mask.dst.u.tcp.port = 0xFFFF;
 163
 164                 if (ip_nat_amanda_hook)
 165                         ret = ip_nat_amanda_hook(pskb, ctinfo, off - dataoff,
 166                                                  len, exp);
 167                 else if (ip_conntrack_expect_related(exp) != 0)
 168                         ret = NF_DROP;
 169                 ip_conntrack_expect_put(exp);
 170         }
 171
 172 out:
 173         return ret;
 174 }
 175
 176 static struct ip_conntrack_helper amanda_helper = {
 177         .max_expected = 3,
 178         .timeout = 180,
 179         .me = THIS_MODULE,
 180         .help = help,
 181         .name = "amanda",
 182
 183         .tuple = { .src = { .u = { __constant_htons(10080) } },
 184                    .dst = { .protonum = IPPROTO_UDP },
 185         },
 186         .mask = { .src = { .u = { 0xFFFF } },
 187                  .dst = { .protonum = 0xFF },
 188         },
 189 };
 190
 191 static void __exit ip_conntrack_amanda_fini(void)
 192 {
 193         int i;
 194
 195         ip_conntrack_helper_unregister(&amanda_helper);
 196         for (i = 0; i < ARRAY_SIZE(search); i++)
 197                 textsearch_destroy(search[i].ts);
 198 }
 199
 200 static int __init ip_conntrack_amanda_init(void)
 201 {
 202         int ret, i;
 203
 204         ret = -ENOMEM;
 205         for (i = 0; i < ARRAY_SIZE(search); i++) {
 206                 search[i].ts = textsearch_prepare(ts_algo, search[i].string,
 207                                                   search[i].len,
 208                                                   GFP_KERNEL, TS_AUTOLOAD);
 209                 if (search[i].ts == NULL)
 210                         goto err;
 211         }
 212         ret = ip_conntrack_helper_register(&amanda_helper);
 213         if (ret < 0)
 214                 goto err;
 215         return 0;
 216
 217 err:
 218         for (; i >= 0; i--) {
 219                 if (search[i].ts)
 220                         textsearch_destroy(search[i].ts);
 221         }
 222         return ret;
 223 }
 224
 225 module_init(ip_conntrack_amanda_init);
 226 module_exit(ip_conntrack_amanda_fini);