net: netfilter: IRC DCC for private clients (a35af3df) · Commits · e / devices / android_kernel_xiaomi_markw

net/netfilter/nf_conntrack_irc.c

+341 −67

Original line number	Diff line number	Diff line
		/* IRC extension for IP connection tracking, Version 1.21
		/* Copyright (c) 2015, The Linux Foundation. All rights reserved.
		* 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>
		*
		* Linux Foundation chooses to take subject only to the GPLv2 license terms,
		* and distributes only under these terms.
		* 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
		@@ -17,6 +20,7 @@
		#include <linux/tcp.h>
		#include <linux/netfilter.h>
		#include <linux/slab.h>
		#include <linux/list.h>

		#include <net/netfilter/nf_conntrack.h>
		#include <net/netfilter/nf_conntrack_expect.h>
		@@ -30,6 +34,18 @@ 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;
		struct irc_client_info {
		char *nickname;
		bool conn_to_server;
		int nickname_len;
		__be32 server_ip;
		__be32 client_ip;
		struct list_head ptr;
		};

		static struct irc_client_info client_list;

		static unsigned int no_of_clients;
		static DEFINE_SPINLOCK(irc_buffer_lock);

		unsigned int (nf_nat_irc_hook)(struct sk_buff skb,
		@@ -59,7 +75,7 @@ static const char *const dccprotos[] = {
		};

		#define MINMATCHLEN 5

		#define MINLENNICK 1
		/* 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
		@@ -69,6 +85,23 @@ static const char *const dccprotos[] = {
		* ad_beg_p returns pointer to first byte of addr data
		* ad_end_p returns pointer to last byte of addr data
		*/
		static struct irc_client_info *search_client_by_ip
		(
		struct nf_conntrack_tuple *tuple
		)
		{
		struct irc_client_info temp, ret = NULL;
		struct list_head obj_ptr, prev_obj_ptr;

		list_for_each_safe(obj_ptr, prev_obj_ptr, &client_list.ptr) {
		temp = list_entry(obj_ptr, struct irc_client_info, ptr);
		if ((temp->client_ip == tuple->src.u3.ip) &&
		(temp->server_ip == tuple->dst.u3.ip))
		ret = temp;
		}
		return ret;
		}

		static int parse_dcc(char data, const char data_end, __be32 *ip,
		u_int16_t port, char ad_beg_p, char *ad_end_p)
		{
		@@ -103,6 +136,105 @@ static int parse_dcc(char data, const char data_end, __be32 *ip,
		return 0;
		}

		static bool mangle_ip(struct nf_conn *ct,
		int dir, char *nick_start)
		{
		char *nick_end;
		struct nf_conntrack_tuple *tuple;
		struct irc_client_info *temp;
		struct list_head obj_ptr, prev_obj_ptr;

		tuple = &ct->tuplehash[dir].tuple;
		nick_end = nick_start;
		while (*nick_end != ' ')
		nick_end++;
		list_for_each_safe(obj_ptr, prev_obj_ptr,
		&client_list.ptr) {
		temp = list_entry(obj_ptr,
		struct irc_client_info, ptr);
		/*If it is an internal client,
		*do not mangle the DCC Server IP
		*/
		if ((temp->server_ip == tuple->dst.u3.ip) &&
		(temp->nickname_len == nick_end - nick_start) &&
		(memcmp(nick_start, temp->nickname,
		temp->nickname_len) == 0))
		return false;
		}
		return true;
		}

		static int handle_nickname(struct nf_conn *ct,
		int dir, char *nick_start)
		{
		char *nick_end;
		struct nf_conntrack_tuple *tuple;
		struct irc_client_info *temp;
		int i, j;
		bool add_entry = true;

		nick_end = nick_start;
		i = 0;
		while (*nick_end != '\n') {
		nick_end++;
		i++;
		}
		tuple = &ct->tuplehash[dir].tuple;
		/*Check if the entry is already
		* present for that client
		*/
		temp = search_client_by_ip(tuple);
		if (temp) {
		add_entry = false;
		/*Update nickname if the client is not already
		* connected to the server.If the client is
		* connected, wait for server to confirm
		* if nickname is valid
		*/
		if (!temp->conn_to_server) {
		kfree(temp->nickname);
		temp->nickname =
		kmalloc(i, GFP_ATOMIC);
		if (temp->nickname) {
		temp->nickname_len = i;
		memcpy(&temp->nickname,
		nick_start, temp->nickname_len);
		} else {
		list_del(&temp->ptr);
		no_of_clients--;
		kfree(temp);
		}
		}
		}
		/Add client entry if not already present/
		if (add_entry) {
		j = sizeof(struct irc_client_info);
		temp = kmalloc(j, GFP_ATOMIC);
		if (temp) {
		no_of_clients++;
		tuple = &ct->tuplehash[dir].tuple;
		temp->nickname_len = i;
		temp->nickname =
		kmalloc(temp->nickname_len, GFP_ATOMIC);
		if (temp->nickname == NULL) {
		kfree(temp);
		return NF_DROP;
		}
		memcpy(temp->nickname, nick_start,
		temp->nickname_len);
		memcpy(&temp->client_ip,
		&tuple->src.u3.ip, sizeof(__be32));
		memcpy(&temp->server_ip,
		&tuple->dst.u3.ip, sizeof(__be32));
		temp->conn_to_server = false;
		list_add(&temp->ptr,
		&client_list.ptr);
		} else {
		return NF_DROP;
		}
		}
		return NF_ACCEPT;
		}
		static int help(struct sk_buff *skb, unsigned int protoff,
		struct nf_conn *ct, enum ip_conntrack_info ctinfo)
		{
		@@ -111,7 +243,7 @@ static int help(struct sk_buff *skb, unsigned int protoff,
		const struct tcphdr *th;
		struct tcphdr _tcph;
		const char *data_limit;
		char data, ib_ptr;
		char data, ib_ptr, for_print, nick_end;
		int dir = CTINFO2DIR(ctinfo);
		struct nf_conntrack_expect *exp;
		struct nf_conntrack_tuple *tuple;
		@@ -121,10 +253,8 @@ static int help(struct sk_buff *skb, unsigned int protoff,
		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;
		struct irc_client_info *temp;
		bool mangle = true;

		/* Until there's been traffic both ways, don't look in packets. */
		if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
		@@ -148,23 +278,132 @@ static int help(struct sk_buff *skb, unsigned int protoff,
		data = ib_ptr;
		data_limit = ib_ptr + skb->len - dataoff;

		/* If packet is coming from IRC server
		* parse the packet for different type of
		* messages (MOTD,NICK etc) and process
		* accordingly
		*/
		if (dir == IP_CT_DIR_REPLY) {
		/* strlen("NICK xxxxxx")
		* 5+strlen("xxxxxx")=1 (minimum length of nickname)
		*/

		while (data < data_limit - 6) {
		if (memcmp(data, " MOTD ", 6)) {
		data++;
		continue;
		}
		/* MOTD message signifies successful
		* registration with server
		*/
		tuple = &ct->tuplehash[!dir].tuple;
		temp = search_client_by_ip(tuple);
		if (temp && !temp->conn_to_server)
		temp->conn_to_server = true;
		ret = NF_ACCEPT;
		goto out;
		}

		/* strlen("NICK :xxxxxx")
		* 6+strlen("xxxxxx")=1 (minimum length of nickname)
		* Parsing the server reply to get nickname
		* of the client
		*/
		data = ib_ptr;
		data_limit = ib_ptr + skb->len - dataoff;
		while (data < data_limit - (6 + MINLENNICK)) {
		if (memcmp(data, "NICK :", 6)) {
		data++;
		continue;
		}
		data += 6;
		nick_end = data;
		i = 0;
		while ((*nick_end != 0x0d) &&
		(*(nick_end + 1) != '\n')) {
		nick_end++;
		i++;
		}
		tuple = &ct->tuplehash[!dir].tuple;
		temp = search_client_by_ip(tuple);
		if (temp && temp->nickname) {
		kfree(temp->nickname);
		temp->nickname = kmalloc(i, GFP_ATOMIC);
		if (temp->nickname) {
		temp->nickname_len = i;
		memcpy(temp->nickname, data,
		temp->nickname_len);
		temp->conn_to_server = true;
		} else {
		list_del(&temp->ptr);
		no_of_clients--;
		kfree(temp);
		ret = NF_ACCEPT;
		}
		}
		/NICK during registration/
		ret = NF_ACCEPT;
		goto out;
		}
		}

		else{
		/*Parsing NICK command from client to create an entry
		* strlen("NICK xxxxxx")
		* 5+strlen("xxxxxx")=1 (minimum length of nickname)
		*/
		data = ib_ptr;
		data_limit = ib_ptr + skb->len - dataoff;
		while (data < data_limit - (5 + MINLENNICK)) {
		if (memcmp(data, "NICK ", 5)) {
		data++;
		continue;
		}
		data += 5;
		ret = handle_nickname(ct, dir, data);
		goto out;
		}

		data = ib_ptr;
		while (data < data_limit - 6) {
		if (memcmp(data, "QUIT :", 6)) {
		data++;
		continue;
		}
		/* Parsing QUIT to free the list entry
		*/
		tuple = &ct->tuplehash[dir].tuple;
		temp = search_client_by_ip(tuple);
		if (temp) {
		list_del(&temp->ptr);
		no_of_clients--;
		kfree(temp->nickname);
		kfree(temp);
		}
		ret = NF_ACCEPT;
		goto out;
		}
		/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
		* 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
		* 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14
		*/
		data = ib_ptr;
		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 */

		/* 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]))) {
		if (memcmp(data, dccprotos[i],
		strlen(dccprotos[i]))) {
		/* no match */
		continue;
		}
		@@ -172,10 +411,12 @@ static int help(struct sk_buff *skb, unsigned int protoff,
		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) */
		* (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)) {
		&dcc_port, &addr_beg_p,
		&addr_end_p)) {
		pr_debug("unable to parse dcc command\n");
		continue;
		}
		@@ -183,7 +424,9 @@ static int help(struct sk_buff *skb, unsigned int protoff,
		pr_debug("DCC bound ip/port: %pI4:%u\n",
		&dcc_ip, dcc_port);

		/* dcc_ip can be the internal OR external (NAT'ed) IP */
		/* 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) {
		@@ -202,18 +445,46 @@ static int help(struct sk_buff *skb, unsigned int protoff,
		}
		tuple = &ct->tuplehash[!dir].tuple;
		port = htons(dcc_port);
		nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
		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,

		tuple = &ct->tuplehash[dir].tuple;
		for_print = ib_ptr;
		/* strlen("PRIVMSG xxxx :\1DCC
		*SENT t AAAAAAAA P\1\n")=26
		* 8+strlen(xxxx) = 1(min length)+7+
		*MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14
		*Parsing DCC command to get client name and
		*check whether it is an internal client
		*/
		while (for_print <
		data_limit - (25 + MINMATCHLEN)) {
		if (memcmp(for_print, "PRIVMSG ", 8)) {
		for_print++;
		continue;
		}
		for_print += 8;
		mangle = mangle_ip(ct,
		dir, for_print);
		break;
		}
		if (mangle &&
		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) {

		else if (mangle &&
		nf_ct_expect_related(exp)
		!= 0) {
		nf_ct_helper_log(skb, ct,
		"cannot add expectation");
		ret = NF_DROP;
		@@ -222,6 +493,7 @@ static int help(struct sk_buff *skb, unsigned int protoff,
		goto out;
		}
		}
		}
		out:
		spin_unlock_bh(&irc_buffer_lock);
		return ret;
		@@ -274,6 +546,8 @@ static int __init nf_conntrack_irc_init(void)
		return ret;
		}
		}
		no_of_clients = 0;
		INIT_LIST_HEAD(&client_list.ptr);
		return 0;
		}