Merge branches 'core/softlockup', 'core/softirq', 'core/resources', 'core/printk...
[linux-2.6] / 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 #include <linux/netfilter.h>
13
14 #include <net/netfilter/nf_conntrack.h>
15 #include <net/netfilter/nf_conntrack_tuple.h>
16 #include <net/netfilter/nf_conntrack_expect.h>
17 #include <net/netfilter/nf_conntrack_ecache.h>
18 #include <net/netfilter/nf_conntrack_helper.h>
19 #include <linux/netfilter/nf_conntrack_tftp.h>
20
21 MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
22 MODULE_DESCRIPTION("TFTP connection tracking helper");
23 MODULE_LICENSE("GPL");
24 MODULE_ALIAS("ip_conntrack_tftp");
25
26 #define MAX_PORTS 8
27 static unsigned short ports[MAX_PORTS];
28 static unsigned int ports_c;
29 module_param_array(ports, ushort, &ports_c, 0400);
30 MODULE_PARM_DESC(ports, "Port numbers of TFTP servers");
31
32 unsigned int (*nf_nat_tftp_hook)(struct sk_buff *skb,
33                                  enum ip_conntrack_info ctinfo,
34                                  struct nf_conntrack_expect *exp) __read_mostly;
35 EXPORT_SYMBOL_GPL(nf_nat_tftp_hook);
36
37 static int tftp_help(struct sk_buff *skb,
38                      unsigned int protoff,
39                      struct nf_conn *ct,
40                      enum ip_conntrack_info ctinfo)
41 {
42         const struct tftphdr *tfh;
43         struct tftphdr _tftph;
44         struct nf_conntrack_expect *exp;
45         struct nf_conntrack_tuple *tuple;
46         unsigned int ret = NF_ACCEPT;
47         typeof(nf_nat_tftp_hook) nf_nat_tftp;
48
49         tfh = skb_header_pointer(skb, protoff + sizeof(struct udphdr),
50                                  sizeof(_tftph), &_tftph);
51         if (tfh == NULL)
52                 return NF_ACCEPT;
53
54         switch (ntohs(tfh->opcode)) {
55         case TFTP_OPCODE_READ:
56         case TFTP_OPCODE_WRITE:
57                 /* RRQ and WRQ works the same way */
58                 nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
59                 nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
60
61                 exp = nf_ct_expect_alloc(ct);
62                 if (exp == NULL)
63                         return NF_DROP;
64                 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
65                 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
66                                   nf_ct_l3num(ct),
67                                   &tuple->src.u3, &tuple->dst.u3,
68                                   IPPROTO_UDP, NULL, &tuple->dst.u.udp.port);
69
70                 pr_debug("expect: ");
71                 nf_ct_dump_tuple(&exp->tuple);
72
73                 nf_nat_tftp = rcu_dereference(nf_nat_tftp_hook);
74                 if (nf_nat_tftp && ct->status & IPS_NAT_MASK)
75                         ret = nf_nat_tftp(skb, ctinfo, exp);
76                 else if (nf_ct_expect_related(exp) != 0)
77                         ret = NF_DROP;
78                 nf_ct_expect_put(exp);
79                 break;
80         case TFTP_OPCODE_DATA:
81         case TFTP_OPCODE_ACK:
82                 pr_debug("Data/ACK opcode\n");
83                 break;
84         case TFTP_OPCODE_ERROR:
85                 pr_debug("Error opcode\n");
86                 break;
87         default:
88                 pr_debug("Unknown opcode\n");
89         }
90         return ret;
91 }
92
93 static struct nf_conntrack_helper tftp[MAX_PORTS][2] __read_mostly;
94 static char tftp_names[MAX_PORTS][2][sizeof("tftp-65535")] __read_mostly;
95
96 static const struct nf_conntrack_expect_policy tftp_exp_policy = {
97         .max_expected   = 1,
98         .timeout        = 5 * 60,
99 };
100
101 static void nf_conntrack_tftp_fini(void)
102 {
103         int i, j;
104
105         for (i = 0; i < ports_c; i++) {
106                 for (j = 0; j < 2; j++)
107                         nf_conntrack_helper_unregister(&tftp[i][j]);
108         }
109 }
110
111 static int __init nf_conntrack_tftp_init(void)
112 {
113         int i, j, ret;
114         char *tmpname;
115
116         if (ports_c == 0)
117                 ports[ports_c++] = TFTP_PORT;
118
119         for (i = 0; i < ports_c; i++) {
120                 memset(&tftp[i], 0, sizeof(tftp[i]));
121
122                 tftp[i][0].tuple.src.l3num = AF_INET;
123                 tftp[i][1].tuple.src.l3num = AF_INET6;
124                 for (j = 0; j < 2; j++) {
125                         tftp[i][j].tuple.dst.protonum = IPPROTO_UDP;
126                         tftp[i][j].tuple.src.u.udp.port = htons(ports[i]);
127                         tftp[i][j].expect_policy = &tftp_exp_policy;
128                         tftp[i][j].me = THIS_MODULE;
129                         tftp[i][j].help = tftp_help;
130
131                         tmpname = &tftp_names[i][j][0];
132                         if (ports[i] == TFTP_PORT)
133                                 sprintf(tmpname, "tftp");
134                         else
135                                 sprintf(tmpname, "tftp-%u", i);
136                         tftp[i][j].name = tmpname;
137
138                         ret = nf_conntrack_helper_register(&tftp[i][j]);
139                         if (ret) {
140                                 printk("nf_ct_tftp: failed to register helper "
141                                        "for pf: %u port: %u\n",
142                                         tftp[i][j].tuple.src.l3num, ports[i]);
143                                 nf_conntrack_tftp_fini();
144                                 return ret;
145                         }
146                 }
147         }
148         return 0;
149 }
150
151 module_init(nf_conntrack_tftp_init);
152 module_exit(nf_conntrack_tftp_fini);