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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 | /* IRC extension for IP connection tracking, Version 1.21 * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org> * based on RR's ip_conntrack_ftp.c * (C) 2006-2012 Patrick McHardy <kaber@trash.net> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/skbuff.h> #include <linux/in.h> #include <linux/ip.h> #include <linux/tcp.h> #include <linux/netfilter.h> #include <linux/slab.h> #include <net/netfilter/nf_conntrack.h> #include <net/netfilter/nf_conntrack_expect.h> #include <net/netfilter/nf_conntrack_helper.h> #include <linux/netfilter/nf_conntrack_irc.h> #define MAX_PORTS 8 static unsigned short ports[MAX_PORTS]; static unsigned int ports_c; static unsigned int max_dcc_channels = 8; static unsigned int dcc_timeout __read_mostly = 300; /* This is slow, but it's simple. --RR */ static char *irc_buffer; static DEFINE_SPINLOCK(irc_buffer_lock); unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb, enum ip_conntrack_info ctinfo, unsigned int protoff, unsigned int matchoff, unsigned int matchlen, struct nf_conntrack_expect *exp) __read_mostly; EXPORT_SYMBOL_GPL(nf_nat_irc_hook); MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); MODULE_LICENSE("GPL"); MODULE_ALIAS("ip_conntrack_irc"); MODULE_ALIAS_NFCT_HELPER("irc"); module_param_array(ports, ushort, &ports_c, 0400); MODULE_PARM_DESC(ports, "port numbers of IRC servers"); module_param(max_dcc_channels, uint, 0400); MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " "IRC session"); module_param(dcc_timeout, uint, 0400); MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); static const char *const dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " }; #define MINMATCHLEN 5 /* tries to get the ip_addr and port out of a dcc command * return value: -1 on failure, 0 on success * data pointer to first byte of DCC command data * data_end pointer to last byte of dcc command data * ip returns parsed ip of dcc command * port returns parsed port of dcc command * ad_beg_p returns pointer to first byte of addr data * ad_end_p returns pointer to last byte of addr data */ static int parse_dcc(char *data, const char *data_end, __be32 *ip, u_int16_t *port, char **ad_beg_p, char **ad_end_p) { char *tmp; /* at least 12: "AAAAAAAA P\1\n" */ while (*data++ != ' ') if (data > data_end - 12) return -1; /* Make sure we have a newline character within the packet boundaries * because simple_strtoul parses until the first invalid character. */ for (tmp = data; tmp <= data_end; tmp++) if (*tmp == '\n') break; if (tmp > data_end || *tmp != '\n') return -1; *ad_beg_p = data; *ip = cpu_to_be32(simple_strtoul(data, &data, 10)); /* skip blanks between ip and port */ while (*data == ' ') { if (data >= data_end) return -1; data++; } *port = simple_strtoul(data, &data, 10); *ad_end_p = data; return 0; } static int help(struct sk_buff *skb, unsigned int protoff, struct nf_conn *ct, enum ip_conntrack_info ctinfo) { unsigned int dataoff; const struct iphdr *iph; const struct tcphdr *th; struct tcphdr _tcph; const char *data_limit; char *data, *ib_ptr; int dir = CTINFO2DIR(ctinfo); struct nf_conntrack_expect *exp; struct nf_conntrack_tuple *tuple; __be32 dcc_ip; u_int16_t dcc_port; __be16 port; int i, ret = NF_ACCEPT; char *addr_beg_p, *addr_end_p; typeof(nf_nat_irc_hook) nf_nat_irc; /* If packet is coming from IRC server */ if (dir == IP_CT_DIR_REPLY) return NF_ACCEPT; /* Until there's been traffic both ways, don't look in packets. */ if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) return NF_ACCEPT; /* Not a full tcp header? */ th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); if (th == NULL) return NF_ACCEPT; /* No data? */ dataoff = protoff + th->doff*4; if (dataoff >= skb->len) return NF_ACCEPT; spin_lock_bh(&irc_buffer_lock); ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, irc_buffer); BUG_ON(ib_ptr == NULL); data = ib_ptr; data_limit = ib_ptr + skb->len - dataoff; /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */ while (data < data_limit - (19 + MINMATCHLEN)) { if (memcmp(data, "\1DCC ", 5)) { data++; continue; } data += 5; /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ iph = ip_hdr(skb); pr_debug("DCC found in master %pI4:%u %pI4:%u\n", &iph->saddr, ntohs(th->source), &iph->daddr, ntohs(th->dest)); for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { /* no match */ continue; } data += strlen(dccprotos[i]); pr_debug("DCC %s detected\n", dccprotos[i]); /* we have at least * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid * data left (== 14/13 bytes) */ if (parse_dcc(data, data_limit, &dcc_ip, &dcc_port, &addr_beg_p, &addr_end_p)) { pr_debug("unable to parse dcc command\n"); continue; } pr_debug("DCC bound ip/port: %pI4:%u\n", &dcc_ip, dcc_port); /* dcc_ip can be the internal OR external (NAT'ed) IP */ tuple = &ct->tuplehash[dir].tuple; if (tuple->src.u3.ip != dcc_ip && tuple->dst.u3.ip != dcc_ip) { net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n", &tuple->src.u3.ip, &dcc_ip, dcc_port); continue; } exp = nf_ct_expect_alloc(ct); if (exp == NULL) { nf_ct_helper_log(skb, ct, "cannot alloc expectation"); ret = NF_DROP; goto out; } tuple = &ct->tuplehash[!dir].tuple; port = htons(dcc_port); nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, tuple->src.l3num, NULL, &tuple->dst.u3, IPPROTO_TCP, NULL, &port); nf_nat_irc = rcu_dereference(nf_nat_irc_hook); if (nf_nat_irc && ct->status & IPS_NAT_MASK) ret = nf_nat_irc(skb, ctinfo, protoff, addr_beg_p - ib_ptr, addr_end_p - addr_beg_p, exp); else if (nf_ct_expect_related(exp) != 0) { nf_ct_helper_log(skb, ct, "cannot add expectation"); ret = NF_DROP; } nf_ct_expect_put(exp); goto out; } } out: spin_unlock_bh(&irc_buffer_lock); return ret; } static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; static struct nf_conntrack_expect_policy irc_exp_policy; static void nf_conntrack_irc_fini(void); static int __init nf_conntrack_irc_init(void) { int i, ret; if (max_dcc_channels < 1) { pr_err("max_dcc_channels must not be zero\n"); return -EINVAL; } irc_exp_policy.max_expected = max_dcc_channels; irc_exp_policy.timeout = dcc_timeout; irc_buffer = kmalloc(65536, GFP_KERNEL); if (!irc_buffer) return -ENOMEM; /* If no port given, default to standard irc port */ if (ports_c == 0) ports[ports_c++] = IRC_PORT; for (i = 0; i < ports_c; i++) { nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, "irc", IRC_PORT, ports[i], i, &irc_exp_policy, 0, 0, help, NULL, THIS_MODULE); } ret = nf_conntrack_helpers_register(&irc[0], ports_c); if (ret) { pr_err("failed to register helpers\n"); kfree(irc_buffer); return ret; } return 0; } /* This function is intentionally _NOT_ defined as __exit, because * it is needed by the init function */ static void nf_conntrack_irc_fini(void) { nf_conntrack_helpers_unregister(irc, ports_c); kfree(irc_buffer); } module_init(nf_conntrack_irc_init); module_exit(nf_conntrack_irc_fini); |