[NETFILTER]: nf_conntrack/nf_nat: add IRC helper port

Add nf_conntrack port of the IRC conntrack/NAT helper. Since DCC doesn't
support IPv6 yet, the helper is still IPv4 only.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 404 insertions, 0 deletions

diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index e14156d1122e..4555f721dfc1 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -500,6 +500,11 @@ config IP_NF_NAT_IRC
         default IP_NF_NAT if IP_NF_IRC=y
         default m if IP_NF_IRC=m
 
+config NF_NAT_IRC
+        tristate
+        depends on IP_NF_IPTABLES && NF_CONNTRACK && NF_NAT
+        default NF_NAT && NF_CONNTRACK_IRC
+
 config IP_NF_NAT_TFTP
         tristate
         depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index bdaba4700e3b..56733c370327 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_IP_NF_NAT_SIP) += ip_nat_sip.o
 obj-$(CONFIG_NF_NAT_AMANDA) += nf_nat_amanda.o
 obj-$(CONFIG_NF_NAT_FTP) += nf_nat_ftp.o
 obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
+obj-$(CONFIG_NF_NAT_IRC) += nf_nat_irc.o
 
 # generic IP tables 
 obj-$(CONFIG_IP_NF_IPTABLES) += ip_tables.o
diff --git a/net/ipv4/netfilter/nf_nat_irc.c b/net/ipv4/netfilter/nf_nat_irc.c
new file mode 100644
index 000000000000..9b8c0daea744
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_irc.c
@@ -0,0 +1,101 @@
+/* IRC extension for TCP NAT alteration.
+ *
+ * (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
+ * based on a copy of RR's ip_nat_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/tcp.h>
+#include <linux/kernel.h>
+
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_irc.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
+MODULE_DESCRIPTION("IRC (DCC) NAT helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_nat_irc");
+
+static unsigned int help(struct sk_buff **pskb,
+                         enum ip_conntrack_info ctinfo,
+                         unsigned int matchoff,
+                         unsigned int matchlen,
+                         struct nf_conntrack_expect *exp)
+{
+        char buffer[sizeof("4294967296 65635")];
+        u_int32_t ip;
+        u_int16_t port;
+        unsigned int ret;
+
+        DEBUGP("IRC_NAT: info (seq %u + %u) in %u\n",
+               expect->seq, exp_irc_info->len, ntohl(tcph->seq));
+
+        /* Reply comes from server. */
+        exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+        exp->dir = IP_CT_DIR_REPLY;
+        exp->expectfn = nf_nat_follow_master;
+
+        /* Try to get same port: if not, try to change it. */
+        for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
+                exp->tuple.dst.u.tcp.port = htons(port);
+                if (nf_conntrack_expect_related(exp) == 0)
+                        break;
+        }
+
+        if (port == 0)
+                return NF_DROP;
+
+        ip = ntohl(exp->master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip);
+        sprintf(buffer, "%u %u", ip, port);
+        DEBUGP("nf_nat_irc: inserting '%s' == %u.%u.%u.%u, port %u\n",
+               buffer, NIPQUAD(ip), port);
+
+        ret = nf_nat_mangle_tcp_packet(pskb, exp->master, ctinfo,
+                                       matchoff, matchlen, buffer,
+                                       strlen(buffer));
+        if (ret != NF_ACCEPT)
+                nf_conntrack_unexpect_related(exp);
+        return ret;
+}
+
+static void __exit nf_nat_irc_fini(void)
+{
+        rcu_assign_pointer(nf_nat_irc_hook, NULL);
+        synchronize_rcu();
+}
+
+static int __init nf_nat_irc_init(void)
+{
+        BUG_ON(rcu_dereference(nf_nat_irc_hook));
+        rcu_assign_pointer(nf_nat_irc_hook, help);
+        return 0;
+}
+
+/* Prior to 2.6.11, we had a ports param.  No longer, but don't break users. */
+static int warn_set(const char *val, struct kernel_param *kp)
+{
+        printk(KERN_INFO KBUILD_MODNAME
+               ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
+        return 0;
+}
+module_param_call(ports, warn_set, NULL, NULL, 0);
+
+module_init(nf_nat_irc_init);
+module_exit(nf_nat_irc_fini);
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index d8f3451c95b6..bd50897d8fbb 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -179,6 +179,21 @@ config NF_CONNTRACK_H323
 
           To compile it as a module, choose M here.  If unsure, say N.
 
+config NF_CONNTRACK_IRC
+        tristate "IRC protocol support (EXPERIMENTAL)"
+        depends on EXPERIMENTAL && NF_CONNTRACK
+        help
+          There is a commonly-used extension to IRC called
+          Direct Client-to-Client Protocol (DCC).  This enables users to send
+          files to each other, and also chat to each other without the need
+          of a server.  DCC Sending is used anywhere you send files over IRC,
+          and DCC Chat is most commonly used by Eggdrop bots.  If you are
+          using NAT, this extension will enable you to send files and initiate
+          chats.  Note that you do NOT need this extension to get files or
+          have others initiate chats, or everything else in IRC.
+
+          To compile it as a module, choose M here.  If unsure, say N.
+
 config NF_CT_NETLINK
         tristate 'Connection tracking netlink interface (EXPERIMENTAL)'
         depends on EXPERIMENTAL && NF_CONNTRACK && NETFILTER_NETLINK
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 69b554576b6b..343fd4896406 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -25,6 +25,7 @@ nf_conntrack_h323-objs := nf_conntrack_h323_main.o nf_conntrack_h323_asn1.o
 obj-$(CONFIG_NF_CONNTRACK_AMANDA) += nf_conntrack_amanda.o
 obj-$(CONFIG_NF_CONNTRACK_FTP) += nf_conntrack_ftp.o
 obj-$(CONFIG_NF_CONNTRACK_H323) += nf_conntrack_h323.o
+obj-$(CONFIG_NF_CONNTRACK_IRC) += nf_conntrack_irc.o
 
 # generic X tables 
 obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o
diff --git a/net/netfilter/nf_conntrack_irc.c b/net/netfilter/nf_conntrack_irc.c
new file mode 100644
index 000000000000..ed01db634399
--- /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);