/* IRC extension for IP connection tracking, Version 1.21 * (C) 2000-2002 by Harald Welte * based on RR's ip_conntrack_ftp.c * * ip_conntrack_irc.c,v 1.21 2002/02/05 14:49:26 laforge Exp * * 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. ** * Module load syntax: * insmod ip_conntrack_irc.o ports=port1,port2,...port * max_dcc_channels=n dcc_timeout=secs * * please give the ports of all IRC servers You wish to connect to. * If You don't specify ports, the default will be port 6667. * With max_dcc_channels you can define the maximum number of not * yet answered DCC channels per IRC session (default 8). * With dcc_timeout you can specify how long the system waits for * an expected DCC channel (default 300 seconds). * */ #include #include #include #include #include #include #include #include #include #define MAX_PORTS 8 static unsigned short ports[MAX_PORTS]; static int ports_c; static unsigned int max_dcc_channels = 8; static unsigned int dcc_timeout = 300; /* This is slow, but it's simple. --RR */ static char *irc_buffer; static DEFINE_SPINLOCK(irc_buffer_lock); unsigned int (*ip_nat_irc_hook)(struct sk_buff **pskb, enum ip_conntrack_info ctinfo, unsigned int matchoff, unsigned int matchlen, struct ip_conntrack_expect *exp); EXPORT_SYMBOL_GPL(ip_nat_irc_hook); MODULE_AUTHOR("Harald Welte "); MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); MODULE_LICENSE("GPL"); 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 *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " }; #define MINMATCHLEN 5 #if 0 #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \ __FILE__, __FUNCTION__ , ## args) #else #define DEBUGP(format, args...) #endif static int parse_dcc(char *data, char *data_end, u_int32_t *ip, u_int16_t *port, char **ad_beg_p, char **ad_end_p) /* 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 */ { /* at least 12: "AAAAAAAA P\1\n" */ while (*data++ != ' ') if (data > data_end - 12) return -1; *ad_beg_p = data; *ip = 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 **pskb, struct ip_conntrack *ct, enum ip_conntrack_info ctinfo) { unsigned int dataoff; struct tcphdr _tcph, *th; char *data, *data_limit, *ib_ptr; int dir = CTINFO2DIR(ctinfo); struct ip_conntrack_expect *exp; u32 seq; u_int32_t dcc_ip; u_int16_t dcc_port; int i, ret = NF_ACCEPT; char *addr_beg_p, *addr_end_p; DEBUGP("entered\n"); /* 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 + IP_CT_IS_REPLY) { DEBUGP("Conntrackinfo = %u\n", ctinfo); return NF_ACCEPT; } /* Not a full tcp header? */ th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4, sizeof(_tcph), &_tcph); if (th == NULL) return NF_ACCEPT; /* No data? */ dataoff = (*pskb)->nh.iph->ihl*4 + th->doff*4; if (dataoff >= (*pskb)->len) return NF_ACCEPT; spin_lock_bh(&irc_buffer_lock); ib_ptr = skb_header_pointer(*pskb, dataoff, (*pskb)->len - dataoff, irc_buffer); BUG_ON(ib_ptr == NULL); data = ib_ptr; data_limit = ib_ptr + (*pskb)->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 */ DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n", NIPQUAD(iph->saddr), ntohs(th->source), NIPQUAD(iph->daddr), ntohs(th->dest)); for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { /* no match */ continue; } DEBUGP("DCC %s detected\n", dccprotos[i]); data += strlen(dccprotos[i]); /* we have at least * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid * data left (== 14/13 bytes) */ if (parse_dcc((char *)data, data_limit, &dcc_ip, &dcc_port, &addr_beg_p, &addr_end_p)) { /* unable to parse */ DEBUGP("unable to parse dcc command\n"); continue; } DEBUGP("DCC bound ip/port: %u.%u.%u.%u:%u\n", HIPQUAD(dcc_ip), dcc_port); /* dcc_ip can be the internal OR external (NAT'ed) IP * Tiago Sousa */ if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip) && ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip != htonl(dcc_ip)) { if (net_ratelimit()) printk(KERN_WARNING "Forged DCC command from " "%u.%u.%u.%u: %u.%u.%u.%u:%u\n", NIPQUAD(ct->tuplehash[dir].tuple.src.ip), HIPQUAD(dcc_ip), dcc_port); continue; } exp = ip_conntrack_expect_alloc(ct); if (exp == NULL) { ret = NF_DROP; goto out; } /* save position of address in dcc string, * necessary for NAT */ DEBUGP("tcph->seq = %u\n", th->seq); seq = ntohl(th->seq) + (addr_beg_p - ib_ptr); /* We refer to the reverse direction ("!dir") * tuples here, because we're expecting * something in the other * direction. * Doesn't matter unless NAT is happening. */ exp->tuple = ((struct ip_conntrack_tuple) { { 0, { 0 } }, { ct->tuplehash[!dir].tuple.dst.ip, { .tcp = { htons(dcc_port) } }, IPPROTO_TCP }}); exp->mask = ((struct ip_conntrack_tuple) { { 0, { 0 } }, { 0xFFFFFFFF, { .tcp = { 0xFFFF } }, 0xFF }}); exp->expectfn = NULL; exp->flags = 0; if (ip_nat_irc_hook) ret = ip_nat_irc_hook(pskb, ctinfo, addr_beg_p - ib_ptr, addr_end_p - addr_beg_p, exp); else if (ip_conntrack_expect_related(exp) != 0) ret = NF_DROP; ip_conntrack_expect_put(exp); goto out; } /* for .. NUM_DCCPROTO */ } /* while data < ... */ out: spin_unlock_bh(&irc_buffer_lock); return ret; } static struct ip_conntrack_helper irc_helpers[MAX_PORTS]; static char irc_names[MAX_PORTS][sizeof("irc-65535")]; static void ip_conntrack_irc_fini(void); static int __init ip_conntrack_irc_init(void) { int i, ret; struct ip_conntrack_helper *hlpr; char *tmpname; if (max_dcc_channels < 1) { printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n"); return -EBUSY; } 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++) { hlpr = &irc_helpers[i]; hlpr->tuple.src.u.tcp.port = htons(ports[i]); hlpr->tuple.dst.protonum = IPPROTO_TCP; hlpr->mask.src.u.tcp.port = 0xFFFF; hlpr->mask.dst.protonum = 0xFF; hlpr->max_expected = max_dcc_channels; hlpr->timeout = dcc_timeout; hlpr->me = THIS_MODULE; hlpr->help = help; tmpname = &irc_names[i][0]; if (ports[i] == IRC_PORT) sprintf(tmpname, "irc"); else sprintf(tmpname, "irc-%d", i); hlpr->name = tmpname; DEBUGP("port #%d: %d\n", i, ports[i]); ret = ip_conntrack_helper_register(hlpr); if (ret) { printk("ip_conntrack_irc: ERROR registering port %d\n", ports[i]); ip_conntrack_irc_fini(); return -EBUSY; } } return 0; } /* This function is intentionally _NOT_ defined as __exit, because * it is needed by the init function */ static void ip_conntrack_irc_fini(void) { int i; for (i = 0; i < ports_c; i++) { DEBUGP("unregistering port %d\n", ports[i]); ip_conntrack_helper_unregister(&irc_helpers[i]); } kfree(irc_buffer); } module_init(ip_conntrack_irc_init); module_exit(ip_conntrack_irc_fini);