Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 1 | /* IRC extension for IP connection tracking, Version 1.21 |
| 2 | * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org> |
| 3 | * based on RR's ip_conntrack_ftp.c |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU General Public License |
| 7 | * as published by the Free Software Foundation; either version |
| 8 | * 2 of the License, or (at your option) any later version. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/module.h> |
| 12 | #include <linux/moduleparam.h> |
| 13 | #include <linux/skbuff.h> |
| 14 | #include <linux/in.h> |
| 15 | #include <linux/tcp.h> |
| 16 | #include <linux/netfilter.h> |
| 17 | |
| 18 | #include <net/netfilter/nf_conntrack.h> |
| 19 | #include <net/netfilter/nf_conntrack_expect.h> |
| 20 | #include <net/netfilter/nf_conntrack_helper.h> |
| 21 | #include <linux/netfilter/nf_conntrack_irc.h> |
| 22 | |
| 23 | #define MAX_PORTS 8 |
| 24 | static unsigned short ports[MAX_PORTS]; |
| 25 | static int ports_c; |
| 26 | static unsigned int max_dcc_channels = 8; |
| 27 | static unsigned int dcc_timeout __read_mostly = 300; |
| 28 | /* This is slow, but it's simple. --RR */ |
| 29 | static char *irc_buffer; |
| 30 | static DEFINE_SPINLOCK(irc_buffer_lock); |
| 31 | |
| 32 | unsigned int (*nf_nat_irc_hook)(struct sk_buff **pskb, |
| 33 | enum ip_conntrack_info ctinfo, |
| 34 | unsigned int matchoff, |
| 35 | unsigned int matchlen, |
| 36 | struct nf_conntrack_expect *exp) __read_mostly; |
| 37 | EXPORT_SYMBOL_GPL(nf_nat_irc_hook); |
| 38 | |
| 39 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| 40 | MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); |
| 41 | MODULE_LICENSE("GPL"); |
| 42 | MODULE_ALIAS("ip_conntrack_irc"); |
| 43 | |
| 44 | module_param_array(ports, ushort, &ports_c, 0400); |
| 45 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); |
| 46 | module_param(max_dcc_channels, uint, 0400); |
| 47 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " |
| 48 | "IRC session"); |
| 49 | module_param(dcc_timeout, uint, 0400); |
| 50 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); |
| 51 | |
| 52 | static const char *dccprotos[] = { |
| 53 | "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " |
| 54 | }; |
| 55 | |
| 56 | #define MINMATCHLEN 5 |
| 57 | |
| 58 | #if 0 |
| 59 | #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \ |
YOSHIFUJI Hideaki | 601e68e | 2007-02-12 11:15:49 -0800 | [diff] [blame] | 60 | __FILE__, __FUNCTION__ , ## args) |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 61 | #else |
| 62 | #define DEBUGP(format, args...) |
| 63 | #endif |
| 64 | |
| 65 | /* tries to get the ip_addr and port out of a dcc command |
| 66 | * return value: -1 on failure, 0 on success |
| 67 | * data pointer to first byte of DCC command data |
| 68 | * data_end pointer to last byte of dcc command data |
| 69 | * ip returns parsed ip of dcc command |
| 70 | * port returns parsed port of dcc command |
| 71 | * ad_beg_p returns pointer to first byte of addr data |
| 72 | * ad_end_p returns pointer to last byte of addr data |
| 73 | */ |
| 74 | static int parse_dcc(char *data, char *data_end, u_int32_t *ip, |
| 75 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
| 76 | { |
| 77 | /* at least 12: "AAAAAAAA P\1\n" */ |
| 78 | while (*data++ != ' ') |
| 79 | if (data > data_end - 12) |
| 80 | return -1; |
| 81 | |
| 82 | *ad_beg_p = data; |
| 83 | *ip = simple_strtoul(data, &data, 10); |
| 84 | |
| 85 | /* skip blanks between ip and port */ |
| 86 | while (*data == ' ') { |
| 87 | if (data >= data_end) |
| 88 | return -1; |
| 89 | data++; |
| 90 | } |
| 91 | |
| 92 | *port = simple_strtoul(data, &data, 10); |
| 93 | *ad_end_p = data; |
| 94 | |
| 95 | return 0; |
| 96 | } |
| 97 | |
| 98 | static int help(struct sk_buff **pskb, unsigned int protoff, |
| 99 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
| 100 | { |
| 101 | unsigned int dataoff; |
| 102 | struct tcphdr _tcph, *th; |
| 103 | char *data, *data_limit, *ib_ptr; |
| 104 | int dir = CTINFO2DIR(ctinfo); |
| 105 | struct nf_conntrack_expect *exp; |
| 106 | struct nf_conntrack_tuple *tuple; |
| 107 | u_int32_t dcc_ip; |
| 108 | u_int16_t dcc_port; |
| 109 | __be16 port; |
| 110 | int i, ret = NF_ACCEPT; |
| 111 | char *addr_beg_p, *addr_end_p; |
| 112 | typeof(nf_nat_irc_hook) nf_nat_irc; |
| 113 | |
| 114 | /* If packet is coming from IRC server */ |
| 115 | if (dir == IP_CT_DIR_REPLY) |
| 116 | return NF_ACCEPT; |
| 117 | |
| 118 | /* Until there's been traffic both ways, don't look in packets. */ |
| 119 | if (ctinfo != IP_CT_ESTABLISHED && |
| 120 | ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) |
| 121 | return NF_ACCEPT; |
| 122 | |
| 123 | /* Not a full tcp header? */ |
| 124 | th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph); |
| 125 | if (th == NULL) |
| 126 | return NF_ACCEPT; |
| 127 | |
| 128 | /* No data? */ |
| 129 | dataoff = protoff + th->doff*4; |
| 130 | if (dataoff >= (*pskb)->len) |
| 131 | return NF_ACCEPT; |
| 132 | |
| 133 | spin_lock_bh(&irc_buffer_lock); |
| 134 | ib_ptr = skb_header_pointer(*pskb, dataoff, (*pskb)->len - dataoff, |
| 135 | irc_buffer); |
| 136 | BUG_ON(ib_ptr == NULL); |
| 137 | |
| 138 | data = ib_ptr; |
| 139 | data_limit = ib_ptr + (*pskb)->len - dataoff; |
| 140 | |
| 141 | /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24 |
| 142 | * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */ |
| 143 | while (data < data_limit - (19 + MINMATCHLEN)) { |
| 144 | if (memcmp(data, "\1DCC ", 5)) { |
| 145 | data++; |
| 146 | continue; |
| 147 | } |
| 148 | data += 5; |
| 149 | /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ |
| 150 | |
| 151 | DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n", |
| 152 | NIPQUAD(iph->saddr), ntohs(th->source), |
| 153 | NIPQUAD(iph->daddr), ntohs(th->dest)); |
| 154 | |
| 155 | for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { |
| 156 | if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { |
| 157 | /* no match */ |
| 158 | continue; |
| 159 | } |
| 160 | data += strlen(dccprotos[i]); |
| 161 | DEBUGP("DCC %s detected\n", dccprotos[i]); |
| 162 | |
| 163 | /* we have at least |
| 164 | * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid |
| 165 | * data left (== 14/13 bytes) */ |
| 166 | if (parse_dcc((char *)data, data_limit, &dcc_ip, |
| 167 | &dcc_port, &addr_beg_p, &addr_end_p)) { |
| 168 | DEBUGP("unable to parse dcc command\n"); |
| 169 | continue; |
| 170 | } |
| 171 | DEBUGP("DCC bound ip/port: %u.%u.%u.%u:%u\n", |
| 172 | HIPQUAD(dcc_ip), dcc_port); |
| 173 | |
| 174 | /* dcc_ip can be the internal OR external (NAT'ed) IP */ |
| 175 | tuple = &ct->tuplehash[dir].tuple; |
| 176 | if (tuple->src.u3.ip != htonl(dcc_ip) && |
| 177 | tuple->dst.u3.ip != htonl(dcc_ip)) { |
| 178 | if (net_ratelimit()) |
| 179 | printk(KERN_WARNING |
| 180 | "Forged DCC command from " |
| 181 | "%u.%u.%u.%u: %u.%u.%u.%u:%u\n", |
| 182 | NIPQUAD(tuple->src.u3.ip), |
| 183 | HIPQUAD(dcc_ip), dcc_port); |
| 184 | continue; |
| 185 | } |
| 186 | |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame^] | 187 | exp = nf_ct_expect_alloc(ct); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 188 | if (exp == NULL) { |
| 189 | ret = NF_DROP; |
| 190 | goto out; |
| 191 | } |
| 192 | tuple = &ct->tuplehash[!dir].tuple; |
| 193 | port = htons(dcc_port); |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame^] | 194 | nf_ct_expect_init(exp, tuple->src.l3num, |
| 195 | NULL, &tuple->dst.u3, |
| 196 | IPPROTO_TCP, NULL, &port); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 197 | |
| 198 | nf_nat_irc = rcu_dereference(nf_nat_irc_hook); |
| 199 | if (nf_nat_irc && ct->status & IPS_NAT_MASK) |
| 200 | ret = nf_nat_irc(pskb, ctinfo, |
| 201 | addr_beg_p - ib_ptr, |
| 202 | addr_end_p - addr_beg_p, |
| 203 | exp); |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame^] | 204 | else if (nf_ct_expect_related(exp) != 0) |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 205 | ret = NF_DROP; |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame^] | 206 | nf_ct_expect_put(exp); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 207 | goto out; |
| 208 | } |
| 209 | } |
| 210 | out: |
| 211 | spin_unlock_bh(&irc_buffer_lock); |
| 212 | return ret; |
| 213 | } |
| 214 | |
| 215 | static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; |
| 216 | static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly; |
| 217 | |
| 218 | static void nf_conntrack_irc_fini(void); |
| 219 | |
| 220 | static int __init nf_conntrack_irc_init(void) |
| 221 | { |
| 222 | int i, ret; |
| 223 | char *tmpname; |
| 224 | |
| 225 | if (max_dcc_channels < 1) { |
| 226 | printk("nf_ct_irc: max_dcc_channels must not be zero\n"); |
| 227 | return -EINVAL; |
| 228 | } |
| 229 | |
| 230 | irc_buffer = kmalloc(65536, GFP_KERNEL); |
| 231 | if (!irc_buffer) |
| 232 | return -ENOMEM; |
| 233 | |
| 234 | /* If no port given, default to standard irc port */ |
| 235 | if (ports_c == 0) |
| 236 | ports[ports_c++] = IRC_PORT; |
| 237 | |
| 238 | for (i = 0; i < ports_c; i++) { |
| 239 | irc[i].tuple.src.l3num = AF_INET; |
| 240 | irc[i].tuple.src.u.tcp.port = htons(ports[i]); |
| 241 | irc[i].tuple.dst.protonum = IPPROTO_TCP; |
| 242 | irc[i].mask.src.l3num = 0xFFFF; |
| 243 | irc[i].mask.src.u.tcp.port = htons(0xFFFF); |
| 244 | irc[i].mask.dst.protonum = 0xFF; |
| 245 | irc[i].max_expected = max_dcc_channels; |
| 246 | irc[i].timeout = dcc_timeout; |
| 247 | irc[i].me = THIS_MODULE; |
| 248 | irc[i].help = help; |
| 249 | |
| 250 | tmpname = &irc_names[i][0]; |
| 251 | if (ports[i] == IRC_PORT) |
| 252 | sprintf(tmpname, "irc"); |
| 253 | else |
| 254 | sprintf(tmpname, "irc-%u", i); |
| 255 | irc[i].name = tmpname; |
| 256 | |
| 257 | ret = nf_conntrack_helper_register(&irc[i]); |
| 258 | if (ret) { |
| 259 | printk("nf_ct_irc: failed to register helper " |
| 260 | "for pf: %u port: %u\n", |
| 261 | irc[i].tuple.src.l3num, ports[i]); |
| 262 | nf_conntrack_irc_fini(); |
| 263 | return ret; |
| 264 | } |
| 265 | } |
| 266 | return 0; |
| 267 | } |
| 268 | |
| 269 | /* This function is intentionally _NOT_ defined as __exit, because |
| 270 | * it is needed by the init function */ |
| 271 | static void nf_conntrack_irc_fini(void) |
| 272 | { |
| 273 | int i; |
| 274 | |
| 275 | for (i = 0; i < ports_c; i++) |
| 276 | nf_conntrack_helper_unregister(&irc[i]); |
| 277 | kfree(irc_buffer); |
| 278 | } |
| 279 | |
| 280 | module_init(nf_conntrack_irc_init); |
| 281 | module_exit(nf_conntrack_irc_fini); |