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
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/netfilter.h>
  24 #include <linux/ip.h>
  25 #include <linux/moduleparam.h>
  26 #include <net/checksum.h>
  27 #include <net/udp.h>
  28
  29 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
  30 #include <linux/netfilter_ipv4/ip_conntrack_amanda.h>
  31
  32 static unsigned int master_timeout = 300;
  33
  34 MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
  35 MODULE_DESCRIPTION("Amanda connection tracking module");
  36 MODULE_LICENSE("GPL");
  37 module_param(master_timeout, int, 0600);
  38 MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
  39
  40 static char *conns[] = { "DATA ", "MESG ", "INDEX " };
  41
  42 /* This is slow, but it's simple. --RR */
  43 static char amanda_buffer[65536];
  44 static DEFINE_SPINLOCK(amanda_buffer_lock);
  45
  46 unsigned int (*ip_nat_amanda_hook)(struct sk_buff **pskb,
  47                                    enum ip_conntrack_info ctinfo,
  48                                    unsigned int matchoff,
  49                                    unsigned int matchlen,
  50                                    struct ip_conntrack_expect *exp);
  51 EXPORT_SYMBOL_GPL(ip_nat_amanda_hook);
  52
  53 static int help(struct sk_buff **pskb,
  54                 struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
  55 {
  56         struct ip_conntrack_expect *exp;
  57         char *data, *data_limit, *tmp;
  58         unsigned int dataoff, i;
  59         u_int16_t port, len;
  60         int ret = NF_ACCEPT;
  61
  62         /* Only look at packets from the Amanda server */
  63         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
  64                 return NF_ACCEPT;
  65
  66         /* increase the UDP timeout of the master connection as replies from
  67          * Amanda clients to the server can be quite delayed */
  68         ip_ct_refresh_acct(ct, ctinfo, NULL, master_timeout * HZ);
  69
  70         /* No data? */
  71         dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
  72         if (dataoff >= (*pskb)->len) {
  73                 if (net_ratelimit())
  74                         printk("amanda_help: skblen = %u\n", (*pskb)->len);
  75                 return NF_ACCEPT;
  76         }
  77
  78         spin_lock_bh(&amanda_buffer_lock);
  79         skb_copy_bits(*pskb, dataoff, amanda_buffer, (*pskb)->len - dataoff);
  80         data = amanda_buffer;
  81         data_limit = amanda_buffer + (*pskb)->len - dataoff;
  82         *data_limit = '\0';
  83
  84         /* Search for the CONNECT string */
  85         data = strstr(data, "CONNECT ");
  86         if (!data)
  87                 goto out;
  88         data += strlen("CONNECT ");
  89
  90         /* Only search first line. */
  91         if ((tmp = strchr(data, '\n')))
  92                 *tmp = '\0';
  93
  94         for (i = 0; i < ARRAY_SIZE(conns); i++) {
  95                 char *match = strstr(data, conns[i]);
  96                 if (!match)
  97                         continue;
  98                 tmp = data = match + strlen(conns[i]);
  99                 port = simple_strtoul(data, &data, 10);
 100                 len = data - tmp;
 101                 if (port == 0 || len > 5)
 102                         break;
 103
 104                 exp = ip_conntrack_expect_alloc(ct);
 105                 if (exp == NULL) {
 106                         ret = NF_DROP;
 107                         goto out;
 108                 }
 109
 110                 exp->expectfn = NULL;
 111
 112                 exp->tuple.src.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
 113                 exp->tuple.src.u.tcp.port = 0;
 114                 exp->tuple.dst.ip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;
 115                 exp->tuple.dst.protonum = IPPROTO_TCP;
 116                 exp->tuple.dst.u.tcp.port = htons(port);
 117
 118                 exp->mask.src.ip = 0xFFFFFFFF;
 119                 exp->mask.src.u.tcp.port = 0;
 120                 exp->mask.dst.ip = 0xFFFFFFFF;
 121                 exp->mask.dst.protonum = 0xFF;
 122                 exp->mask.dst.u.tcp.port = 0xFFFF;
 123
 124                 if (ip_nat_amanda_hook)
 125                         ret = ip_nat_amanda_hook(pskb, ctinfo,
 126                                                  tmp - amanda_buffer,
 127                                                  len, exp);
 128                 else if (ip_conntrack_expect_related(exp) != 0)
 129                         ret = NF_DROP;
 130                 ip_conntrack_expect_put(exp);
 131         }
 132
 133 out:
 134         spin_unlock_bh(&amanda_buffer_lock);
 135         return ret;
 136 }
 137
 138 static struct ip_conntrack_helper amanda_helper = {
 139         .max_expected = ARRAY_SIZE(conns),
 140         .timeout = 180,
 141         .me = THIS_MODULE,
 142         .help = help,
 143         .name = "amanda",
 144
 145         .tuple = { .src = { .u = { __constant_htons(10080) } },
 146                    .dst = { .protonum = IPPROTO_UDP },
 147         },
 148         .mask = { .src = { .u = { 0xFFFF } },
 149                  .dst = { .protonum = 0xFF },
 150         },
 151 };
 152
 153 static void __exit fini(void)
 154 {
 155         ip_conntrack_helper_unregister(&amanda_helper);
 156 }
 157
 158 static int __init init(void)
 159 {
 160         return ip_conntrack_helper_register(&amanda_helper);
 161 }
 162
 163 module_init(init);
 164 module_exit(fini);