![Flavio Leitner](/assets/img/avatar_default.png)
The API allows a conntrack helper to indicate its corresponding NAT helper which then can be loaded and reference counted. Signed-off-by: Flavio Leitner <fbl@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
144 lines
3.9 KiB
C
144 lines
3.9 KiB
C
/* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
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* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/in.h>
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#include <linux/udp.h>
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#include <linux/netfilter.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_tuple.h>
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#include <net/netfilter/nf_conntrack_expect.h>
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#include <net/netfilter/nf_conntrack_ecache.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <linux/netfilter/nf_conntrack_tftp.h>
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#define HELPER_NAME "tftp"
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MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
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MODULE_DESCRIPTION("TFTP connection tracking helper");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ip_conntrack_tftp");
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MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
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#define MAX_PORTS 8
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static unsigned short ports[MAX_PORTS];
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static unsigned int ports_c;
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module_param_array(ports, ushort, &ports_c, 0400);
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MODULE_PARM_DESC(ports, "Port numbers of TFTP servers");
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unsigned int (*nf_nat_tftp_hook)(struct sk_buff *skb,
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enum ip_conntrack_info ctinfo,
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struct nf_conntrack_expect *exp) __read_mostly;
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EXPORT_SYMBOL_GPL(nf_nat_tftp_hook);
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static int tftp_help(struct sk_buff *skb,
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unsigned int protoff,
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struct nf_conn *ct,
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enum ip_conntrack_info ctinfo)
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{
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const struct tftphdr *tfh;
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struct tftphdr _tftph;
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struct nf_conntrack_expect *exp;
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struct nf_conntrack_tuple *tuple;
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unsigned int ret = NF_ACCEPT;
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typeof(nf_nat_tftp_hook) nf_nat_tftp;
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tfh = skb_header_pointer(skb, protoff + sizeof(struct udphdr),
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sizeof(_tftph), &_tftph);
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if (tfh == NULL)
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return NF_ACCEPT;
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switch (ntohs(tfh->opcode)) {
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case TFTP_OPCODE_READ:
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case TFTP_OPCODE_WRITE:
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/* RRQ and WRQ works the same way */
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nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
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nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
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exp = nf_ct_expect_alloc(ct);
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if (exp == NULL) {
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nf_ct_helper_log(skb, ct, "cannot alloc expectation");
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return NF_DROP;
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}
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tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
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nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
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nf_ct_l3num(ct),
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&tuple->src.u3, &tuple->dst.u3,
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IPPROTO_UDP, NULL, &tuple->dst.u.udp.port);
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pr_debug("expect: ");
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nf_ct_dump_tuple(&exp->tuple);
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nf_nat_tftp = rcu_dereference(nf_nat_tftp_hook);
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if (nf_nat_tftp && ct->status & IPS_NAT_MASK)
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ret = nf_nat_tftp(skb, ctinfo, exp);
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else if (nf_ct_expect_related(exp) != 0) {
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nf_ct_helper_log(skb, ct, "cannot add expectation");
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ret = NF_DROP;
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}
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nf_ct_expect_put(exp);
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break;
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case TFTP_OPCODE_DATA:
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case TFTP_OPCODE_ACK:
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pr_debug("Data/ACK opcode\n");
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break;
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case TFTP_OPCODE_ERROR:
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pr_debug("Error opcode\n");
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break;
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default:
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pr_debug("Unknown opcode\n");
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}
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return ret;
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}
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static struct nf_conntrack_helper tftp[MAX_PORTS * 2] __read_mostly;
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static const struct nf_conntrack_expect_policy tftp_exp_policy = {
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.max_expected = 1,
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.timeout = 5 * 60,
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};
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static void __exit nf_conntrack_tftp_fini(void)
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{
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nf_conntrack_helpers_unregister(tftp, ports_c * 2);
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}
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static int __init nf_conntrack_tftp_init(void)
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{
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int i, ret;
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NF_CT_HELPER_BUILD_BUG_ON(0);
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if (ports_c == 0)
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ports[ports_c++] = TFTP_PORT;
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for (i = 0; i < ports_c; i++) {
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nf_ct_helper_init(&tftp[2 * i], AF_INET, IPPROTO_UDP,
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HELPER_NAME, TFTP_PORT, ports[i], i,
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&tftp_exp_policy, 0, tftp_help, NULL,
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THIS_MODULE);
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nf_ct_helper_init(&tftp[2 * i + 1], AF_INET6, IPPROTO_UDP,
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HELPER_NAME, TFTP_PORT, ports[i], i,
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&tftp_exp_policy, 0, tftp_help, NULL,
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THIS_MODULE);
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}
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ret = nf_conntrack_helpers_register(tftp, ports_c * 2);
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if (ret < 0) {
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pr_err("failed to register helpers\n");
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return ret;
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}
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return 0;
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}
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module_init(nf_conntrack_tftp_init);
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module_exit(nf_conntrack_tftp_fini);
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