release/src/linux/linux/net/ipv4/netfilter/ip_conntrack_tftp.c

   1 /*
   2  * Licensed under GNU GPL version 2 Copyright Magnus Boden <mb@ozaba.mine.nu>
   3  * Version: 0.0.7
   4  *
   5  * Thu 21 Mar 2002 Harald Welte <laforge@gnumonks.org>
   6  *      - port to newnat API
   7  *
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/ip.h>
  12 #include <linux/udp.h>
  13
  14 #include <linux/netfilter.h>
  15 #include <linux/netfilter_ipv4/ip_tables.h>
  16 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
  17 #include <linux/netfilter_ipv4/ip_conntrack_tftp.h>
  18
  19 MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
  20 MODULE_DESCRIPTION("Netfilter connection tracking module for tftp");
  21 MODULE_LICENSE("GPL");
  22
  23 #define MAX_PORTS 8
  24 static int ports[MAX_PORTS];
  25 static int ports_c = 0;
  26 #ifdef MODULE_PARM
  27 MODULE_PARM(ports, "1-" __MODULE_STRING(MAX_PORTS) "i");
  28 MODULE_PARM_DESC(ports, "port numbers of tftp servers");
  29 #endif
  30
  31 #define DEBUGP(format, args...)
  32
  33 static int tftp_help(const struct iphdr *iph, size_t len,
  34         struct ip_conntrack *ct,
  35         enum ip_conntrack_info ctinfo)
  36 {
  37         struct udphdr *udph = (void *)iph + iph->ihl * 4;
  38         struct tftphdr *tftph = (void *)udph + 8;
  39         struct ip_conntrack_expect exp;
  40
  41         switch (ntohs(tftph->opcode)) {
  42         /* RRQ and WRQ works the same way */
  43         case TFTP_OPCODE_READ:
  44         case TFTP_OPCODE_WRITE:
  45                 DEBUGP("");
  46                 DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
  47                 DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
  48                 memset(&exp, 0, sizeof(exp));
  49
  50                 exp.tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
  51                 exp.mask.src.ip = 0xffffffff;
  52                 exp.mask.dst.ip = 0xffffffff;
  53                 exp.mask.dst.u.udp.port = 0xffff;
  54                 exp.mask.dst.protonum = 0xffff;
  55                 exp.expectfn = NULL;
  56
  57                 DEBUGP("expect: ");
  58                 DUMP_TUPLE(&exp.tuple);
  59                 DUMP_TUPLE(&exp.mask);
  60                 ip_conntrack_expect_related(ct, &exp);
  61                 break;
  62         default:
  63                 DEBUGP("Unknown opcode\n");
  64         }
  65         return NF_ACCEPT;
  66 }
  67
  68 static struct ip_conntrack_helper tftp[MAX_PORTS];
  69 static char tftp_names[MAX_PORTS][10];
  70
  71 static void fini(void)
  72 {
  73         int i;
  74
  75         for (i = 0 ; i < ports_c; i++) {
  76                 DEBUGP("unregistering helper for port %d\n",
  77                         ports[i]);
  78                 ip_conntrack_helper_unregister(&tftp[i]);
  79         }
  80 }
  81
  82 static int __init init(void)
  83 {
  84         int i, ret;
  85         char *tmpname;
  86
  87         if (!ports[0])
  88                 ports[0]=TFTP_PORT;
  89
  90         for (i = 0 ; (i < MAX_PORTS) && ports[i] ; i++) {
  91                 /* Create helper structure */
  92                 memset(&tftp[i], 0, sizeof(struct ip_conntrack_helper));
  93
  94                 tftp[i].tuple.dst.protonum = IPPROTO_UDP;
  95                 tftp[i].tuple.src.u.udp.port = htons(ports[i]);
  96                 tftp[i].mask.dst.protonum = 0xFFFF;
  97                 tftp[i].mask.src.u.udp.port = 0xFFFF;
  98                 tftp[i].max_expected = 1;
  99                 tftp[i].timeout = 0;
 100                 tftp[i].flags = IP_CT_HELPER_F_REUSE_EXPECT;
 101                 tftp[i].me = THIS_MODULE;
 102                 tftp[i].help = tftp_help;
 103
 104                 tmpname = &tftp_names[i][0];
 105                 if (ports[i] == TFTP_PORT)
 106                         sprintf(tmpname, "tftp");
 107                 else
 108                         sprintf(tmpname, "tftp-%d", i);
 109                 tftp[i].name = tmpname;
 110
 111                 DEBUGP("port #%d: %d\n", i, ports[i]);
 112
 113                 ret=ip_conntrack_helper_register(&tftp[i]);
 114                 if (ret) {
 115                         printk("ERROR registering helper for port %d\n",
 116                                 ports[i]);
 117                         fini();
 118                         return(ret);
 119                 }
 120                 ports_c++;
 121         }
 122         return(0);
 123 }
 124
 125 module_init(init);
 126 module_exit(fini);