IPv6: fix race between cleanup and add/delete address
[linux-2.6.git] / 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 MODULE_ALIAS_NFCT_HELPER("tftp");
26
27 #define MAX_PORTS 8
28 static unsigned short ports[MAX_PORTS];
29 static unsigned int ports_c;
30 module_param_array(ports, ushort, &ports_c, 0400);
31 MODULE_PARM_DESC(ports, "Port numbers of TFTP servers");
32
33 unsigned int (*nf_nat_tftp_hook)(struct sk_buff *skb,
34                                  enum ip_conntrack_info ctinfo,
35                                  struct nf_conntrack_expect *exp) __read_mostly;
36 EXPORT_SYMBOL_GPL(nf_nat_tftp_hook);
37
38 static int tftp_help(struct sk_buff *skb,
39                      unsigned int protoff,
40                      struct nf_conn *ct,
41                      enum ip_conntrack_info ctinfo)
42 {
43         const struct tftphdr *tfh;
44         struct tftphdr _tftph;
45         struct nf_conntrack_expect *exp;
46         struct nf_conntrack_tuple *tuple;
47         unsigned int ret = NF_ACCEPT;
48         typeof(nf_nat_tftp_hook) nf_nat_tftp;
49
50         tfh = skb_header_pointer(skb, protoff + sizeof(struct udphdr),
51                                  sizeof(_tftph), &_tftph);
52         if (tfh == NULL)
53                 return NF_ACCEPT;
54
55         switch (ntohs(tfh->opcode)) {
56         case TFTP_OPCODE_READ:
57         case TFTP_OPCODE_WRITE:
58                 /* RRQ and WRQ works the same way */
59                 nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
60                 nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
61
62                 exp = nf_ct_expect_alloc(ct);
63                 if (exp == NULL)
64                         return NF_DROP;
65                 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
66                 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
67                                   nf_ct_l3num(ct),
68                                   &tuple->src.u3, &tuple->dst.u3,
69                                   IPPROTO_UDP, NULL, &tuple->dst.u.udp.port);
70
71                 pr_debug("expect: ");
72                 nf_ct_dump_tuple(&exp->tuple);
73
74                 nf_nat_tftp = rcu_dereference(nf_nat_tftp_hook);
75                 if (nf_nat_tftp && ct->status & IPS_NAT_MASK)
76                         ret = nf_nat_tftp(skb, ctinfo, exp);
77                 else if (nf_ct_expect_related(exp) != 0)
78                         ret = NF_DROP;
79                 nf_ct_expect_put(exp);
80                 break;
81         case TFTP_OPCODE_DATA:
82         case TFTP_OPCODE_ACK:
83                 pr_debug("Data/ACK opcode\n");
84                 break;
85         case TFTP_OPCODE_ERROR:
86                 pr_debug("Error opcode\n");
87                 break;
88         default:
89                 pr_debug("Unknown opcode\n");
90         }
91         return ret;
92 }
93
94 static struct nf_conntrack_helper tftp[MAX_PORTS][2] __read_mostly;
95 static char tftp_names[MAX_PORTS][2][sizeof("tftp-65535")] __read_mostly;
96
97 static const struct nf_conntrack_expect_policy tftp_exp_policy = {
98         .max_expected   = 1,
99         .timeout        = 5 * 60,
100 };
101
102 static void nf_conntrack_tftp_fini(void)
103 {
104         int i, j;
105
106         for (i = 0; i < ports_c; i++) {
107                 for (j = 0; j < 2; j++)
108                         nf_conntrack_helper_unregister(&tftp[i][j]);
109         }
110 }
111
112 static int __init nf_conntrack_tftp_init(void)
113 {
114         int i, j, ret;
115         char *tmpname;
116
117         if (ports_c == 0)
118                 ports[ports_c++] = TFTP_PORT;
119
120         for (i = 0; i < ports_c; i++) {
121                 memset(&tftp[i], 0, sizeof(tftp[i]));
122
123                 tftp[i][0].tuple.src.l3num = AF_INET;
124                 tftp[i][1].tuple.src.l3num = AF_INET6;
125                 for (j = 0; j < 2; j++) {
126                         tftp[i][j].tuple.dst.protonum = IPPROTO_UDP;
127                         tftp[i][j].tuple.src.u.udp.port = htons(ports[i]);
128                         tftp[i][j].expect_policy = &tftp_exp_policy;
129                         tftp[i][j].me = THIS_MODULE;
130                         tftp[i][j].help = tftp_help;
131
132                         tmpname = &tftp_names[i][j][0];
133                         if (ports[i] == TFTP_PORT)
134                                 sprintf(tmpname, "tftp");
135                         else
136                                 sprintf(tmpname, "tftp-%u", i);
137                         tftp[i][j].name = tmpname;
138
139                         ret = nf_conntrack_helper_register(&tftp[i][j]);
140                         if (ret) {
141                                 printk("nf_ct_tftp: failed to register helper "
142                                        "for pf: %u port: %u\n",
143                                         tftp[i][j].tuple.src.l3num, ports[i]);
144                                 nf_conntrack_tftp_fini();
145                                 return ret;
146                         }
147                 }
148         }
149         return 0;
150 }
151
152 module_init(nf_conntrack_tftp_init);
153 module_exit(nf_conntrack_tftp_fini);