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Release 4.11 net/netfilter/nf_conntrack_sane.c

Directory: net/netfilter
/* SANE connection tracking helper
 * (SANE = Scanner Access Now Easy)
 * For documentation about the SANE network protocol see
 * http://www.sane-project.org/html/doc015.html
 */

/* Copyright (C) 2007 Red Hat, Inc.
 * Author: Michal Schmidt <mschmidt@redhat.com>
 * Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c):
 *  (C) 1999-2001 Paul `Rusty' Russell
 *  (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 *  (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
 *  (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/netfilter.h>
#include <linux/slab.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_sane.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
MODULE_DESCRIPTION("SANE connection tracking helper");
MODULE_ALIAS_NFCT_HELPER("sane");


static char *sane_buffer;

static DEFINE_SPINLOCK(nf_sane_lock);


#define MAX_PORTS 8

static u_int16_t ports[MAX_PORTS];

static unsigned int ports_c;
module_param_array(ports, ushort, &ports_c, 0400);


struct sane_request {
	
__be32 RPC_code;

#define SANE_NET_START      7   /* RPC code */

	
__be32 handle;
};


struct sane_reply_net_start {
	
__be32 status;

#define SANE_STATUS_SUCCESS 0

	
__be16 zero;
	
__be16 port;
	/* other fields aren't interesting for conntrack */
};


static int help(struct sk_buff *skb, unsigned int protoff, struct nf_conn *ct, enum ip_conntrack_info ctinfo) { unsigned int dataoff, datalen; const struct tcphdr *th; struct tcphdr _tcph; void *sb_ptr; int ret = NF_ACCEPT; int dir = CTINFO2DIR(ctinfo); struct nf_ct_sane_master *ct_sane_info = nfct_help_data(ct); struct nf_conntrack_expect *exp; struct nf_conntrack_tuple *tuple; struct sane_request *req; struct sane_reply_net_start *reply; /* 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; datalen = skb->len - dataoff; spin_lock_bh(&nf_sane_lock); sb_ptr = skb_header_pointer(skb, dataoff, datalen, sane_buffer); BUG_ON(sb_ptr == NULL); if (dir == IP_CT_DIR_ORIGINAL) { if (datalen != sizeof(struct sane_request)) goto out; req = sb_ptr; if (req->RPC_code != htonl(SANE_NET_START)) { /* Not an interesting command */ ct_sane_info->state = SANE_STATE_NORMAL; goto out; } /* We're interested in the next reply */ ct_sane_info->state = SANE_STATE_START_REQUESTED; goto out; } /* Is it a reply to an uninteresting command? */ if (ct_sane_info->state != SANE_STATE_START_REQUESTED) goto out; /* It's a reply to SANE_NET_START. */ ct_sane_info->state = SANE_STATE_NORMAL; if (datalen < sizeof(struct sane_reply_net_start)) { pr_debug("NET_START reply too short\n"); goto out; } reply = sb_ptr; if (reply->status != htonl(SANE_STATUS_SUCCESS)) { /* saned refused the command */ pr_debug("unsuccessful SANE_STATUS = %u\n", ntohl(reply->status)); goto out; } /* Invalid saned reply? Ignore it. */ if (reply->zero != 0) goto out; 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[IP_CT_DIR_ORIGINAL].tuple; nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct), &tuple->src.u3, &tuple->dst.u3, IPPROTO_TCP, NULL, &reply->port); pr_debug("expect: "); nf_ct_dump_tuple(&exp->tuple); /* Can't expect this? Best to drop packet now. */ if (nf_ct_expect_related(exp) != 0) { nf_ct_helper_log(skb, ct, "cannot add expectation"); ret = NF_DROP; } nf_ct_expect_put(exp); out: spin_unlock_bh(&nf_sane_lock); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Michal Schmidt40488.21%18.33%
Pablo Neira Ayuso286.11%325.00%
Patrick McHardy132.84%433.33%
Jan Engelhardt71.53%216.67%
Herbert Xu51.09%18.33%
Eric Dumazet10.22%18.33%
Total458100.00%12100.00%

static struct nf_conntrack_helper sane[MAX_PORTS * 2] __read_mostly; static const struct nf_conntrack_expect_policy sane_exp_policy = { .max_expected = 1, .timeout = 5 * 60, }; /* don't make this __exit, since it's called from __init ! */
static void nf_conntrack_sane_fini(void) { nf_conntrack_helpers_unregister(sane, ports_c * 2); kfree(sane_buffer); }

Contributors

PersonTokensPropCommitsCommitProp
Michal Schmidt1881.82%150.00%
Gao Feng418.18%150.00%
Total22100.00%2100.00%


static int __init nf_conntrack_sane_init(void) { int i, ret = 0; sane_buffer = kmalloc(65536, GFP_KERNEL); if (!sane_buffer) return -ENOMEM; if (ports_c == 0) ports[ports_c++] = SANE_PORT; /* FIXME should be configurable whether IPv4 and IPv6 connections are tracked or not - YK */ for (i = 0; i < ports_c; i++) { nf_ct_helper_init(&sane[2 * i], AF_INET, IPPROTO_TCP, "sane", SANE_PORT, ports[i], ports[i], &sane_exp_policy, 0, sizeof(struct nf_ct_sane_master), help, NULL, THIS_MODULE); nf_ct_helper_init(&sane[2 * i + 1], AF_INET6, IPPROTO_TCP, "sane", SANE_PORT, ports[i], ports[i], &sane_exp_policy, 0, sizeof(struct nf_ct_sane_master), help, NULL, THIS_MODULE); } ret = nf_conntrack_helpers_register(sane, ports_c * 2); if (ret < 0) { pr_err("failed to register helpers\n"); kfree(sane_buffer); return ret; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Michal Schmidt11559.59%120.00%
Gao Feng7036.27%120.00%
Pablo Neira Ayuso84.15%360.00%
Total193100.00%5100.00%

module_init(nf_conntrack_sane_init); module_exit(nf_conntrack_sane_fini);

Overall Contributors

PersonTokensPropCommitsCommitProp
Michal Schmidt67579.60%15.88%
Gao Feng758.84%15.88%
Pablo Neira Ayuso485.66%529.41%
Patrick McHardy344.01%529.41%
Jan Engelhardt70.83%211.76%
Herbert Xu50.59%15.88%
Tejun Heo30.35%15.88%
Eric Dumazet10.12%15.88%
Total848100.00%17100.00%
Directory: net/netfilter
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