err.no Git - linux-2.6/blob - net/netfilter/nf_conntrack_tftp.c

   1 /* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License version 2 as
   5  * published by the Free Software Foundation.
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/moduleparam.h>
  10 #include <linux/in.h>
  11 #include <linux/udp.h>
  12
  13 #include <net/netfilter/nf_conntrack.h>
  14 #include <net/netfilter/nf_conntrack_tuple.h>
  15 #include <net/netfilter/nf_conntrack_expect.h>
  16 #include <net/netfilter/nf_conntrack_ecache.h>
  17 #include <net/netfilter/nf_conntrack_helper.h>
  18 #include <linux/netfilter/nf_conntrack_tftp.h>
  19
  20 MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
  21 MODULE_DESCRIPTION("TFTP connection tracking helper");
  22 MODULE_LICENSE("GPL");
  23 MODULE_ALIAS("ip_conntrack_tftp");
  24
  25 #define MAX_PORTS 8
  26 static unsigned short ports[MAX_PORTS];
  27 static int ports_c;
  28 module_param_array(ports, ushort, &ports_c, 0400);
  29 MODULE_PARM_DESC(ports, "Port numbers of TFTP servers");
  30
  31 #if 0
  32 #define DEBUGP(format, args...) printk("%s:%s:" format, \
  33                                        __FILE__, __FUNCTION__ , ## args)
  34 #else
  35 #define DEBUGP(format, args...)
  36 #endif
  37
  38 unsigned int (*nf_nat_tftp_hook)(struct sk_buff **pskb,
  39                                  enum ip_conntrack_info ctinfo,
  40                                  struct nf_conntrack_expect *exp) __read_mostly;
  41 EXPORT_SYMBOL_GPL(nf_nat_tftp_hook);
  42
  43 static int tftp_help(struct sk_buff **pskb,
  44                      unsigned int protoff,
  45                      struct nf_conn *ct,
  46                      enum ip_conntrack_info ctinfo)
  47 {
  48         struct tftphdr _tftph, *tfh;
  49         struct nf_conntrack_expect *exp;
  50         struct nf_conntrack_tuple *tuple;
  51         unsigned int ret = NF_ACCEPT;
  52         int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
  53         typeof(nf_nat_tftp_hook) nf_nat_tftp;
  54
  55         tfh = skb_header_pointer(*pskb, protoff + sizeof(struct udphdr),
  56                                  sizeof(_tftph), &_tftph);
  57         if (tfh == NULL)
  58                 return NF_ACCEPT;
  59
  60         switch (ntohs(tfh->opcode)) {
  61         case TFTP_OPCODE_READ:
  62         case TFTP_OPCODE_WRITE:
  63                 /* RRQ and WRQ works the same way */
  64                 DEBUGP("");
  65                 NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
  66                 NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
  67
  68                 exp = nf_conntrack_expect_alloc(ct);
  69                 if (exp == NULL)
  70                         return NF_DROP;
  71                 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
  72                 nf_conntrack_expect_init(exp, family,
  73                                          &tuple->src.u3, &tuple->dst.u3,
  74                                          IPPROTO_UDP,
  75                                          NULL, &tuple->dst.u.udp.port);
  76
  77                 DEBUGP("expect: ");
  78                 NF_CT_DUMP_TUPLE(&exp->tuple);
  79                 NF_CT_DUMP_TUPLE(&exp->mask);
  80
  81                 nf_nat_tftp = rcu_dereference(nf_nat_tftp_hook);
  82                 if (nf_nat_tftp && ct->status & IPS_NAT_MASK)
  83                         ret = nf_nat_tftp(pskb, ctinfo, exp);
  84                 else if (nf_conntrack_expect_related(exp) != 0)
  85                         ret = NF_DROP;
  86                 nf_conntrack_expect_put(exp);
  87                 break;
  88         case TFTP_OPCODE_DATA:
  89         case TFTP_OPCODE_ACK:
  90                 DEBUGP("Data/ACK opcode\n");
  91                 break;
  92         case TFTP_OPCODE_ERROR:
  93                 DEBUGP("Error opcode\n");
  94                 break;
  95         default:
  96                 DEBUGP("Unknown opcode\n");
  97         }
  98         return ret;
  99 }
 100
 101 static struct nf_conntrack_helper tftp[MAX_PORTS][2] __read_mostly;
 102 static char tftp_names[MAX_PORTS][2][sizeof("tftp-65535")] __read_mostly;
 103
 104 static void nf_conntrack_tftp_fini(void)
 105 {
 106         int i, j;
 107
 108         for (i = 0; i < ports_c; i++) {
 109                 for (j = 0; j < 2; j++)
 110                         nf_conntrack_helper_unregister(&tftp[i][j]);
 111         }
 112 }
 113
 114 static int __init nf_conntrack_tftp_init(void)
 115 {
 116         int i, j, ret;
 117         char *tmpname;
 118
 119         if (ports_c == 0)
 120                 ports[ports_c++] = TFTP_PORT;
 121
 122         for (i = 0; i < ports_c; i++) {
 123                 memset(&tftp[i], 0, sizeof(tftp[i]));
 124
 125                 tftp[i][0].tuple.src.l3num = AF_INET;
 126                 tftp[i][1].tuple.src.l3num = AF_INET6;
 127                 for (j = 0; j < 2; j++) {
 128                         tftp[i][j].tuple.dst.protonum = IPPROTO_UDP;
 129                         tftp[i][j].tuple.src.u.udp.port = htons(ports[i]);
 130                         tftp[i][j].mask.src.l3num = 0xFFFF;
 131                         tftp[i][j].mask.dst.protonum = 0xFF;
 132                         tftp[i][j].mask.src.u.udp.port = htons(0xFFFF);
 133                         tftp[i][j].max_expected = 1;
 134                         tftp[i][j].timeout = 5 * 60; /* 5 minutes */
 135                         tftp[i][j].me = THIS_MODULE;
 136                         tftp[i][j].help = tftp_help;
 137
 138                         tmpname = &tftp_names[i][j][0];
 139                         if (ports[i] == TFTP_PORT)
 140                                 sprintf(tmpname, "tftp");
 141                         else
 142                                 sprintf(tmpname, "tftp-%u", i);
 143                         tftp[i][j].name = tmpname;
 144
 145                         ret = nf_conntrack_helper_register(&tftp[i][j]);
 146                         if (ret) {
 147                                 printk("nf_ct_tftp: failed to register helper "
 148                                        "for pf: %u port: %u\n",
 149                                         tftp[i][j].tuple.src.l3num, ports[i]);
 150                                 nf_conntrack_tftp_fini();
 151                                 return ret;
 152                         }
 153                 }
 154         }
 155         return 0;
 156 }
 157
 158 module_init(nf_conntrack_tftp_init);
 159 module_exit(nf_conntrack_tftp_fini);