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 #if 0
  32 #define DEBUGP(format, args...) printk(__FILE__ ":" __FUNCTION__ ": " \
  33                                        format, ## args)
  34 #else
  35 #define DEBUGP(format, args...)
  36 #endif
  37
  38 static int tftp_help(const struct iphdr *iph, size_t len,
  39         struct ip_conntrack *ct,
  40         enum ip_conntrack_info ctinfo)
  41 {
  42         struct udphdr *udph = (void *)iph + iph->ihl * 4;
  43         struct tftphdr *tftph = (void *)udph + 8;
  44         struct ip_conntrack_expect exp;
  45
  46         switch (ntohs(tftph->opcode)) {
  47         /* RRQ and WRQ works the same way */
  48         case TFTP_OPCODE_READ:
  49         case TFTP_OPCODE_WRITE:
  50                 DEBUGP("");
  51                 DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
  52                 DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
  53                 memset(&exp, 0, sizeof(exp));
  54
  55                 exp.tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
  56                 exp.mask.src.ip = 0xffffffff;
  57                 exp.mask.dst.ip = 0xffffffff;
  58                 exp.mask.dst.u.udp.port = 0xffff;
  59                 exp.mask.dst.protonum = 0xffff;
  60                 exp.expectfn = NULL;
  61
  62                 DEBUGP("expect: ");
  63                 DUMP_TUPLE(&exp.tuple);
  64                 DUMP_TUPLE(&exp.mask);
  65                 ip_conntrack_expect_related(ct, &exp);
  66                 break;
  67         case TFTP_OPCODE_DATA:
  68         case TFTP_OPCODE_ACK:
  69                 DEBUGP("Data/ACK opcode\n");
  70                 break;
  71         case TFTP_OPCODE_ERROR:
  72                 DEBUGP("Error opcode\n");
  73                 break;
  74         default:
  75                 DEBUGP("Unknown opcode\n");
  76         }
  77         return NF_ACCEPT;
  78 }
  79
  80 static struct ip_conntrack_helper tftp[MAX_PORTS];
  81 static char tftp_names[MAX_PORTS][10];
  82
  83 static void fini(void)
  84 {
  85         int i;
  86
  87         for (i = 0 ; i < ports_c; i++) {
  88                 DEBUGP("unregistering helper for port %d\n",
  89                         ports[i]);
  90                 ip_conntrack_helper_unregister(&tftp[i]);
  91         }
  92 }
  93
  94 static int __init init(void)
  95 {
  96         int i, ret;
  97         char *tmpname;
  98
  99         if (!ports[0])
 100                 ports[0]=TFTP_PORT;
 101
 102         for (i = 0 ; (i < MAX_PORTS) && ports[i] ; i++) {
 103                 /* Create helper structure */
 104                 tftp[i].tuple.dst.protonum = IPPROTO_UDP;
 105                 tftp[i].tuple.src.u.udp.port = htons(ports[i]);
 106                 tftp[i].mask.dst.protonum = 0xFFFF;
 107                 tftp[i].mask.src.u.udp.port = 0xFFFF;
 108                 tftp[i].max_expected = 1;
 109                 tftp[i].timeout = 0;
 110                 tftp[i].flags = IP_CT_HELPER_F_REUSE_EXPECT;
 111                 tftp[i].me = THIS_MODULE;
 112                 tftp[i].help = tftp_help;
 113
 114                 tmpname = &tftp_names[i][0];
 115                 if (ports[i] == TFTP_PORT)
 116                         sprintf(tmpname, "tftp");
 117                 else
 118                         sprintf(tmpname, "tftp-%d", i);
 119                 tftp[i].name = tmpname;
 120
 121                 DEBUGP("port #%d: %d\n", i, ports[i]);
 122
 123                 ret=ip_conntrack_helper_register(&tftp[i]);
 124                 if (ret) {
 125                         printk("ERROR registering helper for port %d\n",
 126                                 ports[i]);
 127                         fini();
 128                         return(ret);
 129                 }
 130                 ports_c++;
 131         }
 132         return(0);
 133 }
 134
 135 module_init(init);
 136 module_exit(fini);