| /* 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 |
| * |
| * 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_PORTS> |
| * 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 <linux/config.h> |
| #include <linux/module.h> |
| #include <linux/netfilter.h> |
| #include <linux/ip.h> |
| #include <net/checksum.h> |
| #include <net/tcp.h> |
| |
| #include <linux/netfilter_ipv4/ip_conntrack_helper.h> |
| #include <linux/netfilter_ipv4/ip_conntrack_irc.h> |
| #include <linux/moduleparam.h> |
| |
| #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 <laforge@netfilter.org>"); |
| 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 <mirage@kaotik.org> */ |
| 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 fini(void); |
| |
| static int __init 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]); |
| fini(); |
| return -EBUSY; |
| } |
| } |
| return 0; |
| } |
| |
| /* This function is intentionally _NOT_ defined as __exit, because |
| * it is needed by the init function */ |
| static void 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(init); |
| module_exit(fini); |