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> |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 15 | #include <linux/ip.h> |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 16 | #include <linux/tcp.h> |
| 17 | #include <linux/netfilter.h> |
| 18 | |
| 19 | #include <net/netfilter/nf_conntrack.h> |
| 20 | #include <net/netfilter/nf_conntrack_expect.h> |
| 21 | #include <net/netfilter/nf_conntrack_helper.h> |
| 22 | #include <linux/netfilter/nf_conntrack_irc.h> |
| 23 | |
| 24 | #define MAX_PORTS 8 |
| 25 | static unsigned short ports[MAX_PORTS]; |
Stephen Hemminger | 2f0d2f1 | 2008-01-31 04:08:10 -0800 | [diff] [blame] | 26 | static unsigned int ports_c; |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 27 | static unsigned int max_dcc_channels = 8; |
| 28 | static unsigned int dcc_timeout __read_mostly = 300; |
| 29 | /* This is slow, but it's simple. --RR */ |
| 30 | static char *irc_buffer; |
| 31 | static DEFINE_SPINLOCK(irc_buffer_lock); |
| 32 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 33 | unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb, |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 34 | enum ip_conntrack_info ctinfo, |
| 35 | unsigned int matchoff, |
| 36 | unsigned int matchlen, |
| 37 | struct nf_conntrack_expect *exp) __read_mostly; |
| 38 | EXPORT_SYMBOL_GPL(nf_nat_irc_hook); |
| 39 | |
| 40 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| 41 | MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); |
| 42 | MODULE_LICENSE("GPL"); |
| 43 | MODULE_ALIAS("ip_conntrack_irc"); |
| 44 | |
| 45 | module_param_array(ports, ushort, &ports_c, 0400); |
| 46 | MODULE_PARM_DESC(ports, "port numbers of IRC servers"); |
| 47 | module_param(max_dcc_channels, uint, 0400); |
| 48 | MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " |
| 49 | "IRC session"); |
| 50 | module_param(dcc_timeout, uint, 0400); |
| 51 | MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); |
| 52 | |
Jan Engelhardt | 58c0fb0 | 2008-04-14 11:15:42 +0200 | [diff] [blame] | 53 | static const char *const dccprotos[] = { |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 54 | "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " |
| 55 | }; |
| 56 | |
| 57 | #define MINMATCHLEN 5 |
| 58 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 59 | /* tries to get the ip_addr and port out of a dcc command |
| 60 | * return value: -1 on failure, 0 on success |
| 61 | * data pointer to first byte of DCC command data |
| 62 | * data_end pointer to last byte of dcc command data |
| 63 | * ip returns parsed ip of dcc command |
| 64 | * port returns parsed port of dcc command |
| 65 | * ad_beg_p returns pointer to first byte of addr data |
| 66 | * ad_end_p returns pointer to last byte of addr data |
| 67 | */ |
Jan Engelhardt | 58c0fb0 | 2008-04-14 11:15:42 +0200 | [diff] [blame] | 68 | static int parse_dcc(char *data, const char *data_end, u_int32_t *ip, |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 69 | u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
| 70 | { |
Patrick McHardy | e3b802b | 2008-09-07 18:21:24 -0700 | [diff] [blame^] | 71 | char *tmp; |
| 72 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 73 | /* at least 12: "AAAAAAAA P\1\n" */ |
| 74 | while (*data++ != ' ') |
| 75 | if (data > data_end - 12) |
| 76 | return -1; |
| 77 | |
Patrick McHardy | e3b802b | 2008-09-07 18:21:24 -0700 | [diff] [blame^] | 78 | /* Make sure we have a newline character within the packet boundaries |
| 79 | * because simple_strtoul parses until the first invalid character. */ |
| 80 | for (tmp = data; tmp <= data_end; tmp++) |
| 81 | if (*tmp == '\n') |
| 82 | break; |
| 83 | if (tmp > data_end || *tmp != '\n') |
| 84 | return -1; |
| 85 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 86 | *ad_beg_p = data; |
| 87 | *ip = simple_strtoul(data, &data, 10); |
| 88 | |
| 89 | /* skip blanks between ip and port */ |
| 90 | while (*data == ' ') { |
| 91 | if (data >= data_end) |
| 92 | return -1; |
| 93 | data++; |
| 94 | } |
| 95 | |
| 96 | *port = simple_strtoul(data, &data, 10); |
| 97 | *ad_end_p = data; |
| 98 | |
| 99 | return 0; |
| 100 | } |
| 101 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 102 | static int help(struct sk_buff *skb, unsigned int protoff, |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 103 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
| 104 | { |
| 105 | unsigned int dataoff; |
Jan Engelhardt | 58c0fb0 | 2008-04-14 11:15:42 +0200 | [diff] [blame] | 106 | const struct iphdr *iph; |
| 107 | const struct tcphdr *th; |
| 108 | struct tcphdr _tcph; |
| 109 | const char *data_limit; |
| 110 | char *data, *ib_ptr; |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 111 | int dir = CTINFO2DIR(ctinfo); |
| 112 | struct nf_conntrack_expect *exp; |
| 113 | struct nf_conntrack_tuple *tuple; |
| 114 | u_int32_t dcc_ip; |
| 115 | u_int16_t dcc_port; |
| 116 | __be16 port; |
| 117 | int i, ret = NF_ACCEPT; |
| 118 | char *addr_beg_p, *addr_end_p; |
| 119 | typeof(nf_nat_irc_hook) nf_nat_irc; |
| 120 | |
| 121 | /* If packet is coming from IRC server */ |
| 122 | if (dir == IP_CT_DIR_REPLY) |
| 123 | return NF_ACCEPT; |
| 124 | |
| 125 | /* Until there's been traffic both ways, don't look in packets. */ |
| 126 | if (ctinfo != IP_CT_ESTABLISHED && |
| 127 | ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) |
| 128 | return NF_ACCEPT; |
| 129 | |
| 130 | /* Not a full tcp header? */ |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 131 | th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 132 | if (th == NULL) |
| 133 | return NF_ACCEPT; |
| 134 | |
| 135 | /* No data? */ |
| 136 | dataoff = protoff + th->doff*4; |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 137 | if (dataoff >= skb->len) |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 138 | return NF_ACCEPT; |
| 139 | |
| 140 | spin_lock_bh(&irc_buffer_lock); |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 141 | ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 142 | irc_buffer); |
| 143 | BUG_ON(ib_ptr == NULL); |
| 144 | |
| 145 | data = ib_ptr; |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 146 | data_limit = ib_ptr + skb->len - dataoff; |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 147 | |
| 148 | /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24 |
| 149 | * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */ |
| 150 | while (data < data_limit - (19 + MINMATCHLEN)) { |
| 151 | if (memcmp(data, "\1DCC ", 5)) { |
| 152 | data++; |
| 153 | continue; |
| 154 | } |
| 155 | data += 5; |
| 156 | /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ |
| 157 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 158 | iph = ip_hdr(skb); |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 159 | pr_debug("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u\n", |
| 160 | NIPQUAD(iph->saddr), ntohs(th->source), |
| 161 | NIPQUAD(iph->daddr), ntohs(th->dest)); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 162 | |
| 163 | for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { |
| 164 | if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { |
| 165 | /* no match */ |
| 166 | continue; |
| 167 | } |
| 168 | data += strlen(dccprotos[i]); |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 169 | pr_debug("DCC %s detected\n", dccprotos[i]); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 170 | |
| 171 | /* we have at least |
| 172 | * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid |
| 173 | * data left (== 14/13 bytes) */ |
Jan Engelhardt | 58c0fb0 | 2008-04-14 11:15:42 +0200 | [diff] [blame] | 174 | if (parse_dcc(data, data_limit, &dcc_ip, |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 175 | &dcc_port, &addr_beg_p, &addr_end_p)) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 176 | pr_debug("unable to parse dcc command\n"); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 177 | continue; |
| 178 | } |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 179 | pr_debug("DCC bound ip/port: %u.%u.%u.%u:%u\n", |
| 180 | HIPQUAD(dcc_ip), dcc_port); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 181 | |
| 182 | /* dcc_ip can be the internal OR external (NAT'ed) IP */ |
| 183 | tuple = &ct->tuplehash[dir].tuple; |
| 184 | if (tuple->src.u3.ip != htonl(dcc_ip) && |
| 185 | tuple->dst.u3.ip != htonl(dcc_ip)) { |
| 186 | if (net_ratelimit()) |
| 187 | printk(KERN_WARNING |
| 188 | "Forged DCC command from " |
| 189 | "%u.%u.%u.%u: %u.%u.%u.%u:%u\n", |
| 190 | NIPQUAD(tuple->src.u3.ip), |
| 191 | HIPQUAD(dcc_ip), dcc_port); |
| 192 | continue; |
| 193 | } |
| 194 | |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 195 | exp = nf_ct_expect_alloc(ct); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 196 | if (exp == NULL) { |
| 197 | ret = NF_DROP; |
| 198 | goto out; |
| 199 | } |
| 200 | tuple = &ct->tuplehash[!dir].tuple; |
| 201 | port = htons(dcc_port); |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 202 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
| 203 | tuple->src.l3num, |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 204 | NULL, &tuple->dst.u3, |
| 205 | IPPROTO_TCP, NULL, &port); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 206 | |
| 207 | nf_nat_irc = rcu_dereference(nf_nat_irc_hook); |
| 208 | if (nf_nat_irc && ct->status & IPS_NAT_MASK) |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 209 | ret = nf_nat_irc(skb, ctinfo, |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 210 | addr_beg_p - ib_ptr, |
| 211 | addr_end_p - addr_beg_p, |
| 212 | exp); |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 213 | else if (nf_ct_expect_related(exp) != 0) |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 214 | ret = NF_DROP; |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 215 | nf_ct_expect_put(exp); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 216 | goto out; |
| 217 | } |
| 218 | } |
| 219 | out: |
| 220 | spin_unlock_bh(&irc_buffer_lock); |
| 221 | return ret; |
| 222 | } |
| 223 | |
| 224 | static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; |
| 225 | static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly; |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 226 | static struct nf_conntrack_expect_policy irc_exp_policy; |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 227 | |
| 228 | static void nf_conntrack_irc_fini(void); |
| 229 | |
| 230 | static int __init nf_conntrack_irc_init(void) |
| 231 | { |
| 232 | int i, ret; |
| 233 | char *tmpname; |
| 234 | |
| 235 | if (max_dcc_channels < 1) { |
| 236 | printk("nf_ct_irc: max_dcc_channels must not be zero\n"); |
| 237 | return -EINVAL; |
| 238 | } |
| 239 | |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 240 | irc_exp_policy.max_expected = max_dcc_channels; |
| 241 | irc_exp_policy.timeout = dcc_timeout; |
| 242 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 243 | irc_buffer = kmalloc(65536, GFP_KERNEL); |
| 244 | if (!irc_buffer) |
| 245 | return -ENOMEM; |
| 246 | |
| 247 | /* If no port given, default to standard irc port */ |
| 248 | if (ports_c == 0) |
| 249 | ports[ports_c++] = IRC_PORT; |
| 250 | |
| 251 | for (i = 0; i < ports_c; i++) { |
| 252 | irc[i].tuple.src.l3num = AF_INET; |
| 253 | irc[i].tuple.src.u.tcp.port = htons(ports[i]); |
| 254 | irc[i].tuple.dst.protonum = IPPROTO_TCP; |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 255 | irc[i].expect_policy = &irc_exp_policy; |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 256 | irc[i].me = THIS_MODULE; |
| 257 | irc[i].help = help; |
| 258 | |
| 259 | tmpname = &irc_names[i][0]; |
| 260 | if (ports[i] == IRC_PORT) |
| 261 | sprintf(tmpname, "irc"); |
| 262 | else |
| 263 | sprintf(tmpname, "irc-%u", i); |
| 264 | irc[i].name = tmpname; |
| 265 | |
| 266 | ret = nf_conntrack_helper_register(&irc[i]); |
| 267 | if (ret) { |
| 268 | printk("nf_ct_irc: failed to register helper " |
| 269 | "for pf: %u port: %u\n", |
| 270 | irc[i].tuple.src.l3num, ports[i]); |
| 271 | nf_conntrack_irc_fini(); |
| 272 | return ret; |
| 273 | } |
| 274 | } |
| 275 | return 0; |
| 276 | } |
| 277 | |
| 278 | /* This function is intentionally _NOT_ defined as __exit, because |
| 279 | * it is needed by the init function */ |
| 280 | static void nf_conntrack_irc_fini(void) |
| 281 | { |
| 282 | int i; |
| 283 | |
| 284 | for (i = 0; i < ports_c; i++) |
| 285 | nf_conntrack_helper_unregister(&irc[i]); |
| 286 | kfree(irc_buffer); |
| 287 | } |
| 288 | |
| 289 | module_init(nf_conntrack_irc_init); |
| 290 | module_exit(nf_conntrack_irc_fini); |