cregit-Linux how code gets into the kernel

Release 4.8 net/netfilter/nf_conntrack_irc.c

Directory: net/netfilter
/* IRC extension for IP connection tracking, Version 1.21
 * (C) 2000-2002 by Harald Welte <>
 * based on RR's ip_conntrack_ftp.c
 * (C) 2006-2012 Patrick McHardy <>
 * 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.

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/netfilter.h>
#include <linux/slab.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 unsigned 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 *skb,
				enum ip_conntrack_info ctinfo,
				unsigned int protoff,
				unsigned int matchoff,
				unsigned int matchlen,
				struct nf_conntrack_expect *exp) __read_mostly;


MODULE_AUTHOR("Harald Welte <>");
MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");

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 *const dccprotos[] = {
	"SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "


/* 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, const char *data_end, __be32 *ip, u_int16_t *port, char **ad_beg_p, char **ad_end_p) { char *tmp; /* at least 12: "AAAAAAAA P\1\n" */ while (*data++ != ' ') if (data > data_end - 12) return -1; /* Make sure we have a newline character within the packet boundaries * because simple_strtoul parses until the first invalid character. */ for (tmp = data; tmp <= data_end; tmp++) if (*tmp == '\n') break; if (tmp > data_end || *tmp != '\n') return -1; *ad_beg_p = data; *ip = cpu_to_be32(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; }


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harvey harrisonharvey harrison42.50%125.00%
jan engelhardtjan engelhardt10.62%125.00%

static int help(struct sk_buff *skb, unsigned int protoff, struct nf_conn *ct, enum ip_conntrack_info ctinfo) { unsigned int dataoff; const struct iphdr *iph; const struct tcphdr *th; struct tcphdr _tcph; const char *data_limit; char *data, *ib_ptr; int dir = CTINFO2DIR(ctinfo); struct nf_conntrack_expect *exp; struct nf_conntrack_tuple *tuple; __be32 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_REPLY) return NF_ACCEPT; /* Not a full tcp header? */ th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); if (th == NULL) return NF_ACCEPT; /* No data? */ dataoff = protoff + th->doff*4; if (dataoff >= skb->len) return NF_ACCEPT; spin_lock_bh(&irc_buffer_lock); ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, irc_buffer); BUG_ON(ib_ptr == NULL); data = ib_ptr; data_limit = ib_ptr + skb->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 */ 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]))) { /* no match */ continue; } data += strlen(dccprotos[i]); 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) */ if (parse_dcc(data, data_limit, &dcc_ip, &dcc_port, &addr_beg_p, &addr_end_p)) { pr_debug("unable to parse dcc command\n"); continue; } pr_debug("DCC bound ip/port: %pI4:%u\n", &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 != dcc_ip && tuple->dst.u3.ip != dcc_ip) { net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n", &tuple->src.u3.ip, &dcc_ip, dcc_port); continue; } exp = nf_ct_expect_alloc(ct); if (exp == NULL) { nf_ct_helper_log(skb, ct, "cannot alloc expectation"); ret = NF_DROP; goto out; } tuple = &ct->tuplehash[!dir].tuple; port = htons(dcc_port); 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, addr_beg_p - ib_ptr, addr_end_p - addr_beg_p, exp); else if (nf_ct_expect_related(exp) != 0) { nf_ct_helper_log(skb, ct, "cannot add expectation"); ret = NF_DROP; } nf_ct_expect_put(exp); goto out; } } out: spin_unlock_bh(&irc_buffer_lock); return ret; }


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joe perchesjoe perches10.16%18.33%

static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; static struct nf_conntrack_expect_policy irc_exp_policy; static void nf_conntrack_irc_fini(void);
static int __init nf_conntrack_irc_init(void) { int i, ret; if (max_dcc_channels < 1) { pr_err("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++) { nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, "irc", IRC_PORT, ports[i], i, &irc_exp_policy, 0, 0, help, NULL, THIS_MODULE); } ret = nf_conntrack_helpers_register(&irc[0], ports_c); if (ret) { pr_err("failed to register helpers\n"); kfree(irc_buffer); return ret; } return 0; }


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pablo neira ayusopablo neira ayuso63.68%240.00%

/* This function is intentionally _NOT_ defined as __exit, because * it is needed by the init function */
static void nf_conntrack_irc_fini(void) { nf_conntrack_helpers_unregister(irc, ports_c); kfree(irc_buffer); }


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gao fenggao feng315.00%150.00%

module_init(nf_conntrack_irc_init); module_exit(nf_conntrack_irc_fini);

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Directory: net/netfilter
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