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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 | ||
13 | #include <net/netfilter/nf_conntrack.h> | |
14 | #include <net/netfilter/nf_conntrack_tuple.h> | |
15 | #include <net/netfilter/nf_conntrack_expect.h> | |
16 | #include <net/netfilter/nf_conntrack_ecache.h> | |
17 | #include <net/netfilter/nf_conntrack_helper.h> | |
18 | #include <linux/netfilter/nf_conntrack_tftp.h> | |
19 | ||
20 | MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>"); | |
21 | MODULE_DESCRIPTION("TFTP connection tracking helper"); | |
22 | MODULE_LICENSE("GPL"); | |
23 | MODULE_ALIAS("ip_conntrack_tftp"); | |
24 | ||
25 | #define MAX_PORTS 8 | |
26 | static unsigned short ports[MAX_PORTS]; | |
27 | static int ports_c; | |
28 | module_param_array(ports, ushort, &ports_c, 0400); | |
29 | MODULE_PARM_DESC(ports, "Port numbers of TFTP servers"); | |
30 | ||
31 | #if 0 | |
32 | #define DEBUGP(format, args...) printk("%s:%s:" format, \ | |
33 | __FILE__, __FUNCTION__ , ## args) | |
34 | #else | |
35 | #define DEBUGP(format, args...) | |
36 | #endif | |
37 | ||
38 | unsigned int (*nf_nat_tftp_hook)(struct sk_buff **pskb, | |
39 | enum ip_conntrack_info ctinfo, | |
40 | struct nf_conntrack_expect *exp) __read_mostly; | |
41 | EXPORT_SYMBOL_GPL(nf_nat_tftp_hook); | |
42 | ||
43 | static int tftp_help(struct sk_buff **pskb, | |
44 | unsigned int protoff, | |
45 | struct nf_conn *ct, | |
46 | enum ip_conntrack_info ctinfo) | |
47 | { | |
48 | struct tftphdr _tftph, *tfh; | |
49 | struct nf_conntrack_expect *exp; | |
50 | struct nf_conntrack_tuple *tuple; | |
51 | unsigned int ret = NF_ACCEPT; | |
52 | int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num; | |
53 | typeof(nf_nat_tftp_hook) nf_nat_tftp; | |
54 | ||
55 | tfh = skb_header_pointer(*pskb, protoff + sizeof(struct udphdr), | |
56 | sizeof(_tftph), &_tftph); | |
57 | if (tfh == NULL) | |
58 | return NF_ACCEPT; | |
59 | ||
60 | switch (ntohs(tfh->opcode)) { | |
61 | case TFTP_OPCODE_READ: | |
62 | case TFTP_OPCODE_WRITE: | |
63 | /* RRQ and WRQ works the same way */ | |
64 | DEBUGP(""); | |
65 | NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); | |
66 | NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); | |
67 | ||
68 | exp = nf_conntrack_expect_alloc(ct); | |
69 | if (exp == NULL) | |
70 | return NF_DROP; | |
71 | tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple; | |
72 | nf_conntrack_expect_init(exp, family, | |
73 | &tuple->src.u3, &tuple->dst.u3, | |
74 | IPPROTO_UDP, | |
75 | NULL, &tuple->dst.u.udp.port); | |
76 | ||
77 | DEBUGP("expect: "); | |
78 | NF_CT_DUMP_TUPLE(&exp->tuple); | |
79 | NF_CT_DUMP_TUPLE(&exp->mask); | |
80 | ||
81 | nf_nat_tftp = rcu_dereference(nf_nat_tftp_hook); | |
82 | if (nf_nat_tftp && ct->status & IPS_NAT_MASK) | |
83 | ret = nf_nat_tftp(pskb, ctinfo, exp); | |
84 | else if (nf_conntrack_expect_related(exp) != 0) | |
85 | ret = NF_DROP; | |
86 | nf_conntrack_expect_put(exp); | |
87 | break; | |
88 | case TFTP_OPCODE_DATA: | |
89 | case TFTP_OPCODE_ACK: | |
90 | DEBUGP("Data/ACK opcode\n"); | |
91 | break; | |
92 | case TFTP_OPCODE_ERROR: | |
93 | DEBUGP("Error opcode\n"); | |
94 | break; | |
95 | default: | |
96 | DEBUGP("Unknown opcode\n"); | |
97 | } | |
98 | return ret; | |
99 | } | |
100 | ||
101 | static struct nf_conntrack_helper tftp[MAX_PORTS][2] __read_mostly; | |
102 | static char tftp_names[MAX_PORTS][2][sizeof("tftp-65535")] __read_mostly; | |
103 | ||
104 | static void nf_conntrack_tftp_fini(void) | |
105 | { | |
106 | int i, j; | |
107 | ||
108 | for (i = 0; i < ports_c; i++) { | |
109 | for (j = 0; j < 2; j++) | |
110 | nf_conntrack_helper_unregister(&tftp[i][j]); | |
111 | } | |
112 | } | |
113 | ||
114 | static int __init nf_conntrack_tftp_init(void) | |
115 | { | |
116 | int i, j, ret; | |
117 | char *tmpname; | |
118 | ||
119 | if (ports_c == 0) | |
120 | ports[ports_c++] = TFTP_PORT; | |
121 | ||
122 | for (i = 0; i < ports_c; i++) { | |
123 | memset(&tftp[i], 0, sizeof(tftp[i])); | |
124 | ||
125 | tftp[i][0].tuple.src.l3num = AF_INET; | |
126 | tftp[i][1].tuple.src.l3num = AF_INET6; | |
127 | for (j = 0; j < 2; j++) { | |
128 | tftp[i][j].tuple.dst.protonum = IPPROTO_UDP; | |
129 | tftp[i][j].tuple.src.u.udp.port = htons(ports[i]); | |
130 | tftp[i][j].mask.src.l3num = 0xFFFF; | |
131 | tftp[i][j].mask.dst.protonum = 0xFF; | |
132 | tftp[i][j].mask.src.u.udp.port = htons(0xFFFF); | |
133 | tftp[i][j].max_expected = 1; | |
134 | tftp[i][j].timeout = 5 * 60; /* 5 minutes */ | |
135 | tftp[i][j].me = THIS_MODULE; | |
136 | tftp[i][j].help = tftp_help; | |
137 | ||
138 | tmpname = &tftp_names[i][j][0]; | |
139 | if (ports[i] == TFTP_PORT) | |
140 | sprintf(tmpname, "tftp"); | |
141 | else | |
142 | sprintf(tmpname, "tftp-%u", i); | |
143 | tftp[i][j].name = tmpname; | |
144 | ||
145 | ret = nf_conntrack_helper_register(&tftp[i][j]); | |
146 | if (ret) { | |
147 | printk("nf_ct_tftp: failed to register helper " | |
148 | "for pf: %u port: %u\n", | |
149 | tftp[i][j].tuple.src.l3num, ports[i]); | |
150 | nf_conntrack_tftp_fini(); | |
151 | return ret; | |
152 | } | |
153 | } | |
154 | } | |
155 | return 0; | |
156 | } | |
157 | ||
158 | module_init(nf_conntrack_tftp_init); | |
159 | module_exit(nf_conntrack_tftp_fini); |