571 lines
14 KiB
C
571 lines
14 KiB
C
/* Copyright (c) 2015, The Linux Foundation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 and
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* only version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* IRC extension for IP connection tracking, Version 1.21
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* (C) 2000-2002 by Harald Welte <laforge@gnumonks.org>
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* based on RR's ip_conntrack_ftp.c
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* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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*/
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/skbuff.h>
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#include <linux/in.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/netfilter.h>
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#include <linux/slab.h>
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#include <linux/list.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_expect.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <linux/netfilter/nf_conntrack_irc.h>
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#define MAX_PORTS 8
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static unsigned short ports[MAX_PORTS];
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static unsigned int ports_c;
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static unsigned int max_dcc_channels = 8;
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static unsigned int dcc_timeout __read_mostly = 300;
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/* This is slow, but it's simple. --RR */
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static char *irc_buffer;
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struct irc_client_info {
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char *nickname;
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bool conn_to_server;
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int nickname_len;
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__be32 server_ip;
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__be32 client_ip;
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struct list_head ptr;
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};
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static struct irc_client_info client_list;
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static unsigned int no_of_clients;
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static DEFINE_SPINLOCK(irc_buffer_lock);
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unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
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enum ip_conntrack_info ctinfo,
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unsigned int protoff,
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unsigned int matchoff,
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unsigned int matchlen,
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struct nf_conntrack_expect *exp) __read_mostly;
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EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ip_conntrack_irc");
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MODULE_ALIAS_NFCT_HELPER("irc");
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module_param_array(ports, ushort, &ports_c, 0400);
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MODULE_PARM_DESC(ports, "port numbers of IRC servers");
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module_param(max_dcc_channels, uint, 0400);
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MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
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"IRC session");
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module_param(dcc_timeout, uint, 0400);
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MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
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static const char *const dccprotos[] = {
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"SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
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};
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#define MINMATCHLEN 5
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#define MINLENNICK 1
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/* tries to get the ip_addr and port out of a dcc command
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* return value: -1 on failure, 0 on success
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* data pointer to first byte of DCC command data
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* data_end pointer to last byte of dcc command data
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* ip returns parsed ip of dcc command
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* port returns parsed port of dcc command
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* ad_beg_p returns pointer to first byte of addr data
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* ad_end_p returns pointer to last byte of addr data
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*/
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static struct irc_client_info *search_client_by_ip
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(
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struct nf_conntrack_tuple *tuple
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)
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{
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struct irc_client_info *temp, *ret = NULL;
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struct list_head *obj_ptr, *prev_obj_ptr;
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list_for_each_safe(obj_ptr, prev_obj_ptr, &client_list.ptr) {
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temp = list_entry(obj_ptr, struct irc_client_info, ptr);
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if ((temp->client_ip == tuple->src.u3.ip) &&
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(temp->server_ip == tuple->dst.u3.ip))
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ret = temp;
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}
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return ret;
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}
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static int parse_dcc(char *data, const char *data_end, __be32 *ip,
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u_int16_t *port, char **ad_beg_p, char **ad_end_p)
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{
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char *tmp;
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/* at least 12: "AAAAAAAA P\1\n" */
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while (*data++ != ' ')
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if (data > data_end - 12)
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return -1;
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/* Make sure we have a newline character within the packet boundaries
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* because simple_strtoul parses until the first invalid character. */
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for (tmp = data; tmp <= data_end; tmp++)
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if (*tmp == '\n')
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break;
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if (tmp > data_end || *tmp != '\n')
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return -1;
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*ad_beg_p = data;
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*ip = cpu_to_be32(simple_strtoul(data, &data, 10));
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/* skip blanks between ip and port */
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while (*data == ' ') {
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if (data >= data_end)
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return -1;
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data++;
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}
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*port = simple_strtoul(data, &data, 10);
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*ad_end_p = data;
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return 0;
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}
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static bool mangle_ip(struct nf_conn *ct,
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int dir, char *nick_start)
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{
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char *nick_end;
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struct nf_conntrack_tuple *tuple;
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struct irc_client_info *temp;
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struct list_head *obj_ptr, *prev_obj_ptr;
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tuple = &ct->tuplehash[dir].tuple;
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nick_end = nick_start;
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while (*nick_end != ' ')
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nick_end++;
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list_for_each_safe(obj_ptr, prev_obj_ptr,
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&client_list.ptr) {
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temp = list_entry(obj_ptr,
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struct irc_client_info, ptr);
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/*If it is an internal client,
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*do not mangle the DCC Server IP
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*/
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if ((temp->server_ip == tuple->dst.u3.ip) &&
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(temp->nickname_len == nick_end - nick_start)) {
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if (memcmp(nick_start, temp->nickname,
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temp->nickname_len) == 0)
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return false;
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}
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}
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return true;
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}
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static int handle_nickname(struct nf_conn *ct,
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int dir, char *nick_start)
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{
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char *nick_end;
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struct nf_conntrack_tuple *tuple;
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struct irc_client_info *temp;
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int i, j;
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bool add_entry = true;
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nick_end = nick_start;
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i = 0;
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while (*nick_end != '\n') {
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nick_end++;
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i++;
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}
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tuple = &ct->tuplehash[dir].tuple;
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/*Check if the entry is already
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* present for that client
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*/
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temp = search_client_by_ip(tuple);
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if (temp) {
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add_entry = false;
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/*Update nickname if the client is not already
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* connected to the server.If the client is
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* connected, wait for server to confirm
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* if nickname is valid
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*/
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if (!temp->conn_to_server) {
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kfree(temp->nickname);
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temp->nickname =
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kmalloc(i, GFP_ATOMIC);
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if (temp->nickname) {
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temp->nickname_len = i;
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memcpy(&temp->nickname,
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nick_start, temp->nickname_len);
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} else {
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list_del(&temp->ptr);
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no_of_clients--;
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kfree(temp);
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}
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}
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}
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/*Add client entry if not already present*/
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if (add_entry) {
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j = sizeof(struct irc_client_info);
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temp = kmalloc(j, GFP_ATOMIC);
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if (temp) {
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no_of_clients++;
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tuple = &ct->tuplehash[dir].tuple;
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temp->nickname_len = i;
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temp->nickname =
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kmalloc(temp->nickname_len, GFP_ATOMIC);
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if (temp->nickname == NULL) {
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kfree(temp);
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return NF_DROP;
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}
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memcpy(temp->nickname, nick_start,
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temp->nickname_len);
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memcpy(&temp->client_ip,
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&tuple->src.u3.ip, sizeof(__be32));
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memcpy(&temp->server_ip,
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&tuple->dst.u3.ip, sizeof(__be32));
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temp->conn_to_server = false;
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list_add(&(temp->ptr),
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&(client_list.ptr));
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} else
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return NF_DROP;
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}
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return NF_ACCEPT;
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}
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static int help(struct sk_buff *skb, unsigned int protoff,
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struct nf_conn *ct, enum ip_conntrack_info ctinfo)
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{
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unsigned int dataoff;
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const struct iphdr *iph;
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const struct tcphdr *th;
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struct tcphdr _tcph;
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const char *data_limit;
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char *data, *ib_ptr, *for_print, *nick_end;
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int dir = CTINFO2DIR(ctinfo);
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struct nf_conntrack_expect *exp;
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struct nf_conntrack_tuple *tuple;
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__be32 dcc_ip;
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u_int16_t dcc_port;
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__be16 port;
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int i, ret = NF_ACCEPT;
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char *addr_beg_p, *addr_end_p;
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typeof(nf_nat_irc_hook) nf_nat_irc;
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struct irc_client_info *temp;
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bool mangle = true;
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/* Until there's been traffic both ways, don't look in packets. */
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if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
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return NF_ACCEPT;
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/* Not a full tcp header? */
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th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
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if (th == NULL)
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return NF_ACCEPT;
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/* No data? */
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dataoff = protoff + th->doff*4;
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if (dataoff >= skb->len)
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return NF_ACCEPT;
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spin_lock_bh(&irc_buffer_lock);
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ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
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irc_buffer);
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BUG_ON(ib_ptr == NULL);
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data = ib_ptr;
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data_limit = ib_ptr + skb->len - dataoff;
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/* If packet is coming from IRC server
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* parse the packet for different type of
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* messages (MOTD,NICK etc) and process
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* accordingly
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*/
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if (dir == IP_CT_DIR_REPLY) {
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/* strlen("NICK xxxxxx")
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* 5+strlen("xxxxxx")=1 (minimum length of nickname)
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*/
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while (data < data_limit - 6) {
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if (memcmp(data, " MOTD ", 6)) {
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data++;
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continue;
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}
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/* MOTD message signifies successful
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* registration with server
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*/
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tuple = &ct->tuplehash[!dir].tuple;
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temp = search_client_by_ip(tuple);
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if (temp && !temp->conn_to_server)
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temp->conn_to_server = true;
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ret = NF_ACCEPT;
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goto out;
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}
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/* strlen("NICK :xxxxxx")
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* 6+strlen("xxxxxx")=1 (minimum length of nickname)
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* Parsing the server reply to get nickname
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* of the client
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*/
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data = ib_ptr;
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data_limit = ib_ptr + skb->len - dataoff;
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while (data < data_limit - (6 + MINLENNICK)) {
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if (memcmp(data, "NICK :", 6)) {
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data++;
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continue;
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}
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data += 6;
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nick_end = data;
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i = 0;
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while ((*nick_end != 0x0d) &&
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(*(nick_end + 1) != '\n')) {
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nick_end++;
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i++;
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}
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tuple = &ct->tuplehash[!dir].tuple;
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temp = search_client_by_ip(tuple);
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if (temp && temp->nickname) {
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kfree(temp->nickname);
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temp->nickname = kmalloc(i, GFP_ATOMIC);
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if (temp->nickname) {
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temp->nickname_len = i;
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memcpy(temp->nickname, data,
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temp->nickname_len);
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temp->conn_to_server = true;
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} else {
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list_del(&temp->ptr);
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no_of_clients--;
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kfree(temp);
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ret = NF_ACCEPT;
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}
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}
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/*NICK during registration*/
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ret = NF_ACCEPT;
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goto out;
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}
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}
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else{
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/*Parsing NICK command from client to create an entry
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* strlen("NICK xxxxxx")
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* 5+strlen("xxxxxx")=1 (minimum length of nickname)
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*/
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data = ib_ptr;
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data_limit = ib_ptr + skb->len - dataoff;
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while (data < data_limit - (5 + MINLENNICK)) {
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if (memcmp(data, "NICK ", 5)) {
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data++;
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continue;
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}
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data += 5;
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ret = handle_nickname(ct, dir, data);
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goto out;
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}
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data = ib_ptr;
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while (data < data_limit - 6) {
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if (memcmp(data, "QUIT :", 6)) {
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data++;
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continue;
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}
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/* Parsing QUIT to free the list entry
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*/
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tuple = &ct->tuplehash[dir].tuple;
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temp = search_client_by_ip(tuple);
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if (temp) {
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list_del(&temp->ptr);
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no_of_clients--;
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kfree(temp->nickname);
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kfree(temp);
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}
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ret = NF_ACCEPT;
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goto out;
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}
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/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
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* 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14
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*/
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data = ib_ptr;
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while (data < data_limit - (19 + MINMATCHLEN)) {
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if (memcmp(data, "\1DCC ", 5)) {
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data++;
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continue;
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}
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data += 5;
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/* we have at least (19+MINMATCHLEN)-5
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*bytes valid data left
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*/
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iph = ip_hdr(skb);
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pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
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&iph->saddr, ntohs(th->source),
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&iph->daddr, ntohs(th->dest));
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for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
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if (memcmp(data, dccprotos[i],
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strlen(dccprotos[i]))) {
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/* no match */
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continue;
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}
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data += strlen(dccprotos[i]);
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pr_debug("DCC %s detected\n", dccprotos[i]);
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/* we have at least
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* (19+MINMATCHLEN)-5-dccprotos[i].matchlen
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*bytes valid data left (== 14/13 bytes)
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*/
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if (parse_dcc(data, data_limit, &dcc_ip,
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&dcc_port, &addr_beg_p,
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&addr_end_p)) {
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pr_debug("unable to parse dcc command\n");
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continue;
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}
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pr_debug("DCC bound ip/port: %pI4:%u\n",
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&dcc_ip, dcc_port);
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/* dcc_ip can be the internal OR
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*external (NAT'ed) IP
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*/
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tuple = &ct->tuplehash[dir].tuple;
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if (tuple->src.u3.ip != dcc_ip &&
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tuple->dst.u3.ip != dcc_ip) {
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net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n",
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&tuple->src.u3.ip,
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&dcc_ip, dcc_port);
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continue;
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}
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exp = nf_ct_expect_alloc(ct);
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if (exp == NULL) {
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nf_ct_helper_log(skb, ct,
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"cannot alloc expectation");
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ret = NF_DROP;
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goto out;
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}
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tuple = &ct->tuplehash[!dir].tuple;
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port = htons(dcc_port);
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nf_ct_expect_init(exp,
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NF_CT_EXPECT_CLASS_DEFAULT,
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tuple->src.l3num,
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NULL, &tuple->dst.u3,
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IPPROTO_TCP, NULL, &port);
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nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
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tuple = &ct->tuplehash[dir].tuple;
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for_print = ib_ptr;
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/* strlen("PRIVMSG xxxx :\1DCC
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*SENT t AAAAAAAA P\1\n")=26
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* 8+strlen(xxxx) = 1(min length)+7+
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*MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14
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*Parsing DCC command to get client name and
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*check whether it is an internal client
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*/
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while (for_print <
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data_limit - (25 + MINMATCHLEN)) {
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if (memcmp(for_print, "PRIVMSG ", 8)) {
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for_print++;
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continue;
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}
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for_print += 8;
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mangle = mangle_ip(ct,
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dir, for_print);
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break;
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}
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if (mangle &&
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nf_nat_irc &&
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ct->status & IPS_NAT_MASK)
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ret = nf_nat_irc(skb, ctinfo,
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protoff,
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addr_beg_p - ib_ptr,
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addr_end_p - addr_beg_p,
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exp);
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else if (mangle &&
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nf_ct_expect_related(exp)
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!= 0) {
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nf_ct_helper_log(skb, ct,
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"cannot add expectation");
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ret = NF_DROP;
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}
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nf_ct_expect_put(exp);
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goto out;
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}
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}
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}
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out:
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spin_unlock_bh(&irc_buffer_lock);
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return ret;
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}
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static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
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static struct nf_conntrack_expect_policy irc_exp_policy;
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static void nf_conntrack_irc_fini(void);
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static int __init nf_conntrack_irc_init(void)
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{
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int i, ret;
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|
|
if (max_dcc_channels < 1) {
|
|
printk(KERN_ERR "nf_ct_irc: max_dcc_channels must not be zero\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
irc_exp_policy.max_expected = max_dcc_channels;
|
|
irc_exp_policy.timeout = dcc_timeout;
|
|
|
|
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].expect_policy = &irc_exp_policy;
|
|
irc[i].me = THIS_MODULE;
|
|
irc[i].help = help;
|
|
|
|
if (ports[i] == IRC_PORT)
|
|
sprintf(irc[i].name, "irc");
|
|
else
|
|
sprintf(irc[i].name, "irc-%u", i);
|
|
|
|
ret = nf_conntrack_helper_register(&irc[i]);
|
|
if (ret) {
|
|
printk(KERN_ERR "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;
|
|
}
|
|
}
|
|
no_of_clients = 0;
|
|
INIT_LIST_HEAD(&client_list.ptr);
|
|
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);
|