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- /* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
- * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
- * 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");
- MODULE_ALIAS_NFCT_HELPER("tftp");
- #define MAX_PORTS 8
- static unsigned short ports[MAX_PORTS];
- static unsigned 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)
- {
- const struct tftphdr *tfh;
- struct tftphdr _tftph;
- struct nf_conntrack_expect *exp;
- struct nf_conntrack_tuple *tuple;
- unsigned int ret = NF_ACCEPT;
- 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) {
- nf_ct_helper_log(skb, ct, "cannot alloc expectation");
- return NF_DROP;
- }
- tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
- nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
- nf_ct_l3num(ct),
- &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) {
- nf_ct_helper_log(skb, ct, "cannot add expectation");
- 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 const struct nf_conntrack_expect_policy tftp_exp_policy = {
- .max_expected = 1,
- .timeout = 5 * 60,
- };
- 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;
- 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].expect_policy = &tftp_exp_policy;
- tftp[i][j].me = THIS_MODULE;
- tftp[i][j].help = tftp_help;
- if (ports[i] == TFTP_PORT)
- sprintf(tftp[i][j].name, "tftp");
- else
- sprintf(tftp[i][j].name, "tftp-%u", i);
- ret = nf_conntrack_helper_register(&tftp[i][j]);
- if (ret) {
- printk(KERN_ERR "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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