| /* (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); |