Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [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 | * ip_conntrack_irc.c,v 1.21 2002/02/05 14:49:26 laforge Exp |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU General Public License |
| 9 | * as published by the Free Software Foundation; either version |
| 10 | * 2 of the License, or (at your option) any later version. |
| 11 | ** |
| 12 | * Module load syntax: |
| 13 | * insmod ip_conntrack_irc.o ports=port1,port2,...port<MAX_PORTS> |
| 14 | * max_dcc_channels=n dcc_timeout=secs |
| 15 | * |
| 16 | * please give the ports of all IRC servers You wish to connect to. |
| 17 | * If You don't specify ports, the default will be port 6667. |
| 18 | * With max_dcc_channels you can define the maximum number of not |
| 19 | * yet answered DCC channels per IRC session (default 8). |
| 20 | * With dcc_timeout you can specify how long the system waits for |
| 21 | * an expected DCC channel (default 300 seconds). |
| 22 | * |
| 23 | */ |
| 24 | |
| 25 | #include <linux/config.h> |
| 26 | #include <linux/module.h> |
| 27 | #include <linux/netfilter.h> |
| 28 | #include <linux/ip.h> |
| 29 | #include <net/checksum.h> |
| 30 | #include <net/tcp.h> |
| 31 | |
| 32 | #include <linux/netfilter_ipv4/lockhelp.h> |
| 33 | #include <linux/netfilter_ipv4/ip_conntrack_helper.h> |
| 34 | #include <linux/netfilter_ipv4/ip_conntrack_irc.h> |
| 35 | #include <linux/moduleparam.h> |
| 36 | |
| 37 | #define MAX_PORTS 8 |
| 38 | static int ports[MAX_PORTS]; |
| 39 | static int ports_c; |
| 40 | static int max_dcc_channels = 8; |
| 41 | static unsigned int dcc_timeout = 300; |
| 42 | /* This is slow, but it's simple. --RR */ |
| 43 | static char irc_buffer[65536]; |
| 44 | static DECLARE_LOCK(irc_buffer_lock); |
| 45 | |
| 46 | unsigned int (*ip_nat_irc_hook)(struct sk_buff **pskb, |
| 47 | enum ip_conntrack_info ctinfo, |
| 48 | unsigned int matchoff, |
| 49 | unsigned int matchlen, |
| 50 | struct ip_conntrack_expect *exp); |
| 51 | EXPORT_SYMBOL_GPL(ip_nat_irc_hook); |
| 52 | |
| 53 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| 54 | MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); |
| 55 | MODULE_LICENSE("GPL"); |
| 56 | module_param_array(ports, int, &ports_c, 0400); |
| 57 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); |
| 58 | module_param(max_dcc_channels, int, 0400); |
| 59 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per IRC session"); |
| 60 | module_param(dcc_timeout, int, 0400); |
| 61 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); |
| 62 | |
| 63 | static char *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " }; |
| 64 | #define MINMATCHLEN 5 |
| 65 | |
| 66 | #if 0 |
| 67 | #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \ |
| 68 | __FILE__, __FUNCTION__ , ## args) |
| 69 | #else |
| 70 | #define DEBUGP(format, args...) |
| 71 | #endif |
| 72 | |
| 73 | static int parse_dcc(char *data, char *data_end, u_int32_t *ip, |
| 74 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
| 75 | /* tries to get the ip_addr and port out of a dcc command |
| 76 | return value: -1 on failure, 0 on success |
| 77 | data pointer to first byte of DCC command data |
| 78 | data_end pointer to last byte of dcc command data |
| 79 | ip returns parsed ip of dcc command |
| 80 | port returns parsed port of dcc command |
| 81 | ad_beg_p returns pointer to first byte of addr data |
| 82 | ad_end_p returns pointer to last byte of addr data */ |
| 83 | { |
| 84 | |
| 85 | /* at least 12: "AAAAAAAA P\1\n" */ |
| 86 | while (*data++ != ' ') |
| 87 | if (data > data_end - 12) |
| 88 | return -1; |
| 89 | |
| 90 | *ad_beg_p = data; |
| 91 | *ip = simple_strtoul(data, &data, 10); |
| 92 | |
| 93 | /* skip blanks between ip and port */ |
| 94 | while (*data == ' ') { |
| 95 | if (data >= data_end) |
| 96 | return -1; |
| 97 | data++; |
| 98 | } |
| 99 | |
| 100 | *port = simple_strtoul(data, &data, 10); |
| 101 | *ad_end_p = data; |
| 102 | |
| 103 | return 0; |
| 104 | } |
| 105 | |
| 106 | static int help(struct sk_buff **pskb, |
| 107 | struct ip_conntrack *ct, enum ip_conntrack_info ctinfo) |
| 108 | { |
| 109 | unsigned int dataoff; |
| 110 | struct tcphdr _tcph, *th; |
| 111 | char *data, *data_limit, *ib_ptr; |
| 112 | int dir = CTINFO2DIR(ctinfo); |
| 113 | struct ip_conntrack_expect *exp; |
| 114 | u32 seq; |
| 115 | u_int32_t dcc_ip; |
| 116 | u_int16_t dcc_port; |
| 117 | int i, ret = NF_ACCEPT; |
| 118 | char *addr_beg_p, *addr_end_p; |
| 119 | |
| 120 | DEBUGP("entered\n"); |
| 121 | |
| 122 | /* If packet is coming from IRC server */ |
| 123 | if (dir == IP_CT_DIR_REPLY) |
| 124 | return NF_ACCEPT; |
| 125 | |
| 126 | /* Until there's been traffic both ways, don't look in packets. */ |
| 127 | if (ctinfo != IP_CT_ESTABLISHED |
| 128 | && ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) { |
| 129 | DEBUGP("Conntrackinfo = %u\n", ctinfo); |
| 130 | return NF_ACCEPT; |
| 131 | } |
| 132 | |
| 133 | /* Not a full tcp header? */ |
| 134 | th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4, |
| 135 | sizeof(_tcph), &_tcph); |
| 136 | if (th == NULL) |
| 137 | return NF_ACCEPT; |
| 138 | |
| 139 | /* No data? */ |
| 140 | dataoff = (*pskb)->nh.iph->ihl*4 + th->doff*4; |
| 141 | if (dataoff >= (*pskb)->len) |
| 142 | return NF_ACCEPT; |
| 143 | |
| 144 | LOCK_BH(&irc_buffer_lock); |
| 145 | ib_ptr = skb_header_pointer(*pskb, dataoff, |
| 146 | (*pskb)->len - dataoff, irc_buffer); |
| 147 | BUG_ON(ib_ptr == NULL); |
| 148 | |
| 149 | data = ib_ptr; |
| 150 | data_limit = ib_ptr + (*pskb)->len - dataoff; |
| 151 | |
| 152 | /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24 |
| 153 | * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */ |
| 154 | while (data < (data_limit - (19 + MINMATCHLEN))) { |
| 155 | if (memcmp(data, "\1DCC ", 5)) { |
| 156 | data++; |
| 157 | continue; |
| 158 | } |
| 159 | |
| 160 | data += 5; |
| 161 | /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ |
| 162 | |
| 163 | DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n", |
| 164 | NIPQUAD(iph->saddr), ntohs(th->source), |
| 165 | NIPQUAD(iph->daddr), ntohs(th->dest)); |
| 166 | |
| 167 | for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { |
| 168 | if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { |
| 169 | /* no match */ |
| 170 | continue; |
| 171 | } |
| 172 | |
| 173 | DEBUGP("DCC %s detected\n", dccprotos[i]); |
| 174 | data += strlen(dccprotos[i]); |
| 175 | /* we have at least |
| 176 | * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid |
| 177 | * data left (== 14/13 bytes) */ |
| 178 | if (parse_dcc((char *)data, data_limit, &dcc_ip, |
| 179 | &dcc_port, &addr_beg_p, &addr_end_p)) { |
| 180 | /* unable to parse */ |
| 181 | DEBUGP("unable to parse dcc command\n"); |
| 182 | continue; |
| 183 | } |
| 184 | DEBUGP("DCC bound ip/port: %u.%u.%u.%u:%u\n", |
| 185 | HIPQUAD(dcc_ip), dcc_port); |
| 186 | |
| 187 | /* dcc_ip can be the internal OR external (NAT'ed) IP |
| 188 | * Tiago Sousa <mirage@kaotik.org> */ |
| 189 | if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip) |
| 190 | && ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip != htonl(dcc_ip)) { |
| 191 | if (net_ratelimit()) |
| 192 | printk(KERN_WARNING |
| 193 | "Forged DCC command from " |
| 194 | "%u.%u.%u.%u: %u.%u.%u.%u:%u\n", |
| 195 | NIPQUAD(ct->tuplehash[dir].tuple.src.ip), |
| 196 | HIPQUAD(dcc_ip), dcc_port); |
| 197 | |
| 198 | continue; |
| 199 | } |
| 200 | |
| 201 | exp = ip_conntrack_expect_alloc(); |
| 202 | if (exp == NULL) { |
| 203 | ret = NF_DROP; |
| 204 | goto out; |
| 205 | } |
| 206 | |
| 207 | /* save position of address in dcc string, |
| 208 | * necessary for NAT */ |
| 209 | DEBUGP("tcph->seq = %u\n", th->seq); |
| 210 | seq = ntohl(th->seq) + (addr_beg_p - ib_ptr); |
| 211 | |
| 212 | /* We refer to the reverse direction ("!dir") |
| 213 | * tuples here, because we're expecting |
| 214 | * something in the other * direction. |
| 215 | * Doesn't matter unless NAT is happening. */ |
| 216 | exp->tuple = ((struct ip_conntrack_tuple) |
| 217 | { { 0, { 0 } }, |
| 218 | { ct->tuplehash[!dir].tuple.dst.ip, |
| 219 | { .tcp = { htons(dcc_port) } }, |
| 220 | IPPROTO_TCP }}); |
| 221 | exp->mask = ((struct ip_conntrack_tuple) |
| 222 | { { 0, { 0 } }, |
| 223 | { 0xFFFFFFFF, { .tcp = { 0xFFFF } }, 0xFF }}); |
| 224 | exp->expectfn = NULL; |
| 225 | exp->master = ct; |
| 226 | if (ip_nat_irc_hook) |
| 227 | ret = ip_nat_irc_hook(pskb, ctinfo, |
| 228 | addr_beg_p - ib_ptr, |
| 229 | addr_end_p - addr_beg_p, |
| 230 | exp); |
| 231 | else if (ip_conntrack_expect_related(exp) != 0) { |
| 232 | ip_conntrack_expect_free(exp); |
| 233 | ret = NF_DROP; |
| 234 | } |
| 235 | goto out; |
| 236 | } /* for .. NUM_DCCPROTO */ |
| 237 | } /* while data < ... */ |
| 238 | |
| 239 | out: |
| 240 | UNLOCK_BH(&irc_buffer_lock); |
| 241 | return ret; |
| 242 | } |
| 243 | |
| 244 | static struct ip_conntrack_helper irc_helpers[MAX_PORTS]; |
| 245 | static char irc_names[MAX_PORTS][10]; |
| 246 | |
| 247 | static void fini(void); |
| 248 | |
| 249 | static int __init init(void) |
| 250 | { |
| 251 | int i, ret; |
| 252 | struct ip_conntrack_helper *hlpr; |
| 253 | char *tmpname; |
| 254 | |
| 255 | if (max_dcc_channels < 1) { |
| 256 | printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n"); |
| 257 | return -EBUSY; |
| 258 | } |
| 259 | if (dcc_timeout < 0) { |
| 260 | printk("ip_conntrack_irc: dcc_timeout must be a positive integer\n"); |
| 261 | return -EBUSY; |
| 262 | } |
| 263 | |
| 264 | /* If no port given, default to standard irc port */ |
| 265 | if (ports_c == 0) |
| 266 | ports[ports_c++] = IRC_PORT; |
| 267 | |
| 268 | for (i = 0; i < ports_c; i++) { |
| 269 | hlpr = &irc_helpers[i]; |
| 270 | hlpr->tuple.src.u.tcp.port = htons(ports[i]); |
| 271 | hlpr->tuple.dst.protonum = IPPROTO_TCP; |
| 272 | hlpr->mask.src.u.tcp.port = 0xFFFF; |
| 273 | hlpr->mask.dst.protonum = 0xFF; |
| 274 | hlpr->max_expected = max_dcc_channels; |
| 275 | hlpr->timeout = dcc_timeout; |
| 276 | hlpr->me = THIS_MODULE; |
| 277 | hlpr->help = help; |
| 278 | |
| 279 | tmpname = &irc_names[i][0]; |
| 280 | if (ports[i] == IRC_PORT) |
| 281 | sprintf(tmpname, "irc"); |
| 282 | else |
| 283 | sprintf(tmpname, "irc-%d", i); |
| 284 | hlpr->name = tmpname; |
| 285 | |
| 286 | DEBUGP("port #%d: %d\n", i, ports[i]); |
| 287 | |
| 288 | ret = ip_conntrack_helper_register(hlpr); |
| 289 | |
| 290 | if (ret) { |
| 291 | printk("ip_conntrack_irc: ERROR registering port %d\n", |
| 292 | ports[i]); |
| 293 | fini(); |
| 294 | return -EBUSY; |
| 295 | } |
| 296 | } |
| 297 | return 0; |
| 298 | } |
| 299 | |
| 300 | /* This function is intentionally _NOT_ defined as __exit, because |
| 301 | * it is needed by the init function */ |
| 302 | static void fini(void) |
| 303 | { |
| 304 | int i; |
| 305 | for (i = 0; i < ports_c; i++) { |
| 306 | DEBUGP("unregistering port %d\n", |
| 307 | ports[i]); |
| 308 | ip_conntrack_helper_unregister(&irc_helpers[i]); |
| 309 | } |
| 310 | } |
| 311 | |
| 312 | module_init(init); |
| 313 | module_exit(fini); |