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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> | |
1863f096 | 12 | #include <linux/netfilter.h> |
a536df35 PM |
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 int ports_c; | |
29 | module_param_array(ports, ushort, &ports_c, 0400); | |
30 | MODULE_PARM_DESC(ports, "Port numbers of TFTP servers"); | |
31 | ||
32 | #if 0 | |
33 | #define DEBUGP(format, args...) printk("%s:%s:" format, \ | |
601e68e1 | 34 | __FILE__, __FUNCTION__ , ## args) |
a536df35 PM |
35 | #else |
36 | #define DEBUGP(format, args...) | |
37 | #endif | |
38 | ||
39 | unsigned int (*nf_nat_tftp_hook)(struct sk_buff **pskb, | |
40 | enum ip_conntrack_info ctinfo, | |
41 | struct nf_conntrack_expect *exp) __read_mostly; | |
42 | EXPORT_SYMBOL_GPL(nf_nat_tftp_hook); | |
43 | ||
44 | static int tftp_help(struct sk_buff **pskb, | |
45 | unsigned int protoff, | |
46 | struct nf_conn *ct, | |
47 | enum ip_conntrack_info ctinfo) | |
48 | { | |
49 | struct tftphdr _tftph, *tfh; | |
50 | struct nf_conntrack_expect *exp; | |
51 | struct nf_conntrack_tuple *tuple; | |
52 | unsigned int ret = NF_ACCEPT; | |
53 | int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num; | |
54 | typeof(nf_nat_tftp_hook) nf_nat_tftp; | |
55 | ||
56 | tfh = skb_header_pointer(*pskb, protoff + sizeof(struct udphdr), | |
57 | sizeof(_tftph), &_tftph); | |
58 | if (tfh == NULL) | |
59 | return NF_ACCEPT; | |
60 | ||
61 | switch (ntohs(tfh->opcode)) { | |
62 | case TFTP_OPCODE_READ: | |
63 | case TFTP_OPCODE_WRITE: | |
64 | /* RRQ and WRQ works the same way */ | |
65 | DEBUGP(""); | |
66 | NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); | |
67 | NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); | |
68 | ||
69 | exp = nf_conntrack_expect_alloc(ct); | |
70 | if (exp == NULL) | |
71 | return NF_DROP; | |
72 | tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple; | |
73 | nf_conntrack_expect_init(exp, family, | |
74 | &tuple->src.u3, &tuple->dst.u3, | |
75 | IPPROTO_UDP, | |
76 | NULL, &tuple->dst.u.udp.port); | |
77 | ||
78 | DEBUGP("expect: "); | |
79 | NF_CT_DUMP_TUPLE(&exp->tuple); | |
80 | NF_CT_DUMP_TUPLE(&exp->mask); | |
81 | ||
82 | nf_nat_tftp = rcu_dereference(nf_nat_tftp_hook); | |
83 | if (nf_nat_tftp && ct->status & IPS_NAT_MASK) | |
84 | ret = nf_nat_tftp(pskb, ctinfo, exp); | |
85 | else if (nf_conntrack_expect_related(exp) != 0) | |
86 | ret = NF_DROP; | |
87 | nf_conntrack_expect_put(exp); | |
88 | break; | |
89 | case TFTP_OPCODE_DATA: | |
90 | case TFTP_OPCODE_ACK: | |
91 | DEBUGP("Data/ACK opcode\n"); | |
92 | break; | |
93 | case TFTP_OPCODE_ERROR: | |
94 | DEBUGP("Error opcode\n"); | |
95 | break; | |
96 | default: | |
97 | DEBUGP("Unknown opcode\n"); | |
98 | } | |
99 | return ret; | |
100 | } | |
101 | ||
102 | static struct nf_conntrack_helper tftp[MAX_PORTS][2] __read_mostly; | |
103 | static char tftp_names[MAX_PORTS][2][sizeof("tftp-65535")] __read_mostly; | |
104 | ||
105 | static void nf_conntrack_tftp_fini(void) | |
106 | { | |
107 | int i, j; | |
108 | ||
109 | for (i = 0; i < ports_c; i++) { | |
110 | for (j = 0; j < 2; j++) | |
111 | nf_conntrack_helper_unregister(&tftp[i][j]); | |
112 | } | |
113 | } | |
114 | ||
115 | static int __init nf_conntrack_tftp_init(void) | |
116 | { | |
117 | int i, j, ret; | |
118 | char *tmpname; | |
119 | ||
120 | if (ports_c == 0) | |
121 | ports[ports_c++] = TFTP_PORT; | |
122 | ||
123 | for (i = 0; i < ports_c; i++) { | |
124 | memset(&tftp[i], 0, sizeof(tftp[i])); | |
125 | ||
126 | tftp[i][0].tuple.src.l3num = AF_INET; | |
127 | tftp[i][1].tuple.src.l3num = AF_INET6; | |
128 | for (j = 0; j < 2; j++) { | |
129 | tftp[i][j].tuple.dst.protonum = IPPROTO_UDP; | |
130 | tftp[i][j].tuple.src.u.udp.port = htons(ports[i]); | |
131 | tftp[i][j].mask.src.l3num = 0xFFFF; | |
132 | tftp[i][j].mask.dst.protonum = 0xFF; | |
133 | tftp[i][j].mask.src.u.udp.port = htons(0xFFFF); | |
134 | tftp[i][j].max_expected = 1; | |
135 | tftp[i][j].timeout = 5 * 60; /* 5 minutes */ | |
136 | tftp[i][j].me = THIS_MODULE; | |
137 | tftp[i][j].help = tftp_help; | |
138 | ||
139 | tmpname = &tftp_names[i][j][0]; | |
140 | if (ports[i] == TFTP_PORT) | |
141 | sprintf(tmpname, "tftp"); | |
142 | else | |
143 | sprintf(tmpname, "tftp-%u", i); | |
144 | tftp[i][j].name = tmpname; | |
145 | ||
146 | ret = nf_conntrack_helper_register(&tftp[i][j]); | |
147 | if (ret) { | |
148 | printk("nf_ct_tftp: failed to register helper " | |
149 | "for pf: %u port: %u\n", | |
150 | tftp[i][j].tuple.src.l3num, ports[i]); | |
151 | nf_conntrack_tftp_fini(); | |
152 | return ret; | |
153 | } | |
154 | } | |
155 | } | |
156 | return 0; | |
157 | } | |
158 | ||
159 | module_init(nf_conntrack_tftp_init); | |
160 | module_exit(nf_conntrack_tftp_fini); |