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