diff options
Diffstat (limited to 'net/netfilter/nf_conntrack_irc.c')
| -rw-r--r-- | net/netfilter/nf_conntrack_irc.c | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_irc.c b/net/netfilter/nf_conntrack_irc.c new file mode 100644 index 00000000000..ed01db63439 --- /dev/null +++ b/net/netfilter/nf_conntrack_irc.c @@ -0,0 +1,281 @@ +/* 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 + * + * 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. + */ + +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/skbuff.h> +#include <linux/in.h> +#include <linux/tcp.h> +#include <linux/netfilter.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 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 **pskb, + enum ip_conntrack_info ctinfo, + 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_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 + +/* 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, char *data_end, u_int32_t *ip, + u_int16_t *port, char **ad_beg_p, char **ad_end_p) +{ + /* 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, unsigned int protoff, + struct nf_conn *ct, enum ip_conntrack_info ctinfo) +{ + unsigned int dataoff; + struct tcphdr _tcph, *th; + char *data, *data_limit, *ib_ptr; + int dir = CTINFO2DIR(ctinfo); + struct nf_conntrack_expect *exp; + struct nf_conntrack_tuple *tuple; + u_int32_t 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 + IP_CT_IS_REPLY) + return NF_ACCEPT; + + /* Not a full tcp header? */ + th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph); + if (th == NULL) + return NF_ACCEPT; + + /* No data? */ + dataoff = protoff + 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; + } + data += strlen(dccprotos[i]); + DEBUGP("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((char *)data, data_limit, &dcc_ip, + &dcc_port, &addr_beg_p, &addr_end_p)) { + 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 */ + tuple = &ct->tuplehash[dir].tuple; + if (tuple->src.u3.ip != htonl(dcc_ip) && + tuple->dst.u3.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(tuple->src.u3.ip), + HIPQUAD(dcc_ip), dcc_port); + continue; + } + + exp = nf_conntrack_expect_alloc(ct); + if (exp == NULL) { + ret = NF_DROP; + goto out; + } + tuple = &ct->tuplehash[!dir].tuple; + port = htons(dcc_port); + nf_conntrack_expect_init(exp, 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(pskb, ctinfo, + addr_beg_p - ib_ptr, + addr_end_p - addr_beg_p, + exp); + else if (nf_conntrack_expect_related(exp) != 0) + ret = NF_DROP; + nf_conntrack_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 char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly; + +static void nf_conntrack_irc_fini(void); + +static int __init nf_conntrack_irc_init(void) +{ + int i, ret; + char *tmpname; + + if (max_dcc_channels < 1) { + printk("nf_ct_irc: max_dcc_channels must not be zero\n"); + return -EINVAL; + } + + 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++) { + irc[i].tuple.src.l3num = AF_INET; + irc[i].tuple.src.u.tcp.port = htons(ports[i]); + irc[i].tuple.dst.protonum = IPPROTO_TCP; + irc[i].mask.src.l3num = 0xFFFF; + irc[i].mask.src.u.tcp.port = htons(0xFFFF); + irc[i].mask.dst.protonum = 0xFF; + irc[i].max_expected = max_dcc_channels; + irc[i].timeout = dcc_timeout; + irc[i].me = THIS_MODULE; + irc[i].help = help; + + tmpname = &irc_names[i][0]; + if (ports[i] == IRC_PORT) + sprintf(tmpname, "irc"); + else + sprintf(tmpname, "irc-%u", i); + irc[i].name = tmpname; + + ret = nf_conntrack_helper_register(&irc[i]); + if (ret) { + printk("nf_ct_irc: failed to register helper " + "for pf: %u port: %u\n", + irc[i].tuple.src.l3num, ports[i]); + nf_conntrack_irc_fini(); + 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) +{ + int i; + + for (i = 0; i < ports_c; i++) + nf_conntrack_helper_unregister(&irc[i]); + kfree(irc_buffer); +} + +module_init(nf_conntrack_irc_init); +module_exit(nf_conntrack_irc_fini); |