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root/net/netfilter/nf_conntrack_amanda.c

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DEFINITIONS

This source file includes following definitions.
  1. amanda_help
  2. nf_conntrack_amanda_fini
  3. nf_conntrack_amanda_init

/* Amanda extension for IP connection tracking
 *
 * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
 * based on HW's ip_conntrack_irc.c as well as other modules
 *
 * 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/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/textsearch.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/udp.h>
#include <linux/netfilter.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <linux/netfilter/nf_conntrack_amanda.h>

static unsigned int master_timeout __read_mostly = 300;
static char *ts_algo = "kmp";

MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
MODULE_DESCRIPTION("Amanda connection tracking module");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ip_conntrack_amanda");

module_param(master_timeout, uint, 0600);
MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
module_param(ts_algo, charp, 0400);
MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");

unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
                                   enum ip_conntrack_info ctinfo,
                                   unsigned int matchoff,
                                   unsigned int matchlen,
                                   struct nf_conntrack_expect *exp)
                                   __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_amanda_hook);

enum amanda_strings {
        SEARCH_CONNECT,
        SEARCH_NEWLINE,
        SEARCH_DATA,
        SEARCH_MESG,
        SEARCH_INDEX,
};

static struct {
        const char              *string;
        size_t                  len;
        struct ts_config        *ts;
} search[] __read_mostly = {
        [SEARCH_CONNECT] = {
                .string = "CONNECT ",
                .len    = 8,
        },
        [SEARCH_NEWLINE] = {
                .string = "\n",
                .len    = 1,
        },
        [SEARCH_DATA] = {
                .string = "DATA ",
                .len    = 5,
        },
        [SEARCH_MESG] = {
                .string = "MESG ",
                .len    = 5,
        },
        [SEARCH_INDEX] = {
                .string = "INDEX ",
                .len    = 6,
        },
};

static int amanda_help(struct sk_buff *skb,
                       unsigned int protoff,
                       struct nf_conn *ct,
                       enum ip_conntrack_info ctinfo)
{
        struct ts_state ts;
        struct nf_conntrack_expect *exp;
        struct nf_conntrack_tuple *tuple;
        unsigned int dataoff, start, stop, off, i;
        char pbuf[sizeof("65535")], *tmp;
        u_int16_t len;
        __be16 port;
        int ret = NF_ACCEPT;
        typeof(nf_nat_amanda_hook) nf_nat_amanda;

        /* Only look at packets from the Amanda server */
        if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
                return NF_ACCEPT;

        /* increase the UDP timeout of the master connection as replies from
         * Amanda clients to the server can be quite delayed */
        nf_ct_refresh(ct, skb, master_timeout * HZ);

        /* No data? */
        dataoff = protoff + sizeof(struct udphdr);
        if (dataoff >= skb->len) {
                if (net_ratelimit())
                        printk("amanda_help: skblen = %u\n", skb->len);
                return NF_ACCEPT;
        }

        memset(&ts, 0, sizeof(ts));
        start = skb_find_text(skb, dataoff, skb->len,
                              search[SEARCH_CONNECT].ts, &ts);
        if (start == UINT_MAX)
                goto out;
        start += dataoff + search[SEARCH_CONNECT].len;

        memset(&ts, 0, sizeof(ts));
        stop = skb_find_text(skb, start, skb->len,
                             search[SEARCH_NEWLINE].ts, &ts);
        if (stop == UINT_MAX)
                goto out;
        stop += start;

        for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) {
                memset(&ts, 0, sizeof(ts));
                off = skb_find_text(skb, start, stop, search[i].ts, &ts);
                if (off == UINT_MAX)
                        continue;
                off += start + search[i].len;

                len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off);
                if (skb_copy_bits(skb, off, pbuf, len))
                        break;
                pbuf[len] = '\0';

                port = htons(simple_strtoul(pbuf, &tmp, 10));
                len = tmp - pbuf;
                if (port == 0 || len > 5)
                        break;

                exp = nf_ct_expect_alloc(ct);
                if (exp == NULL) {
                        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, &port);

                nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook);
                if (nf_nat_amanda && ct->status & IPS_NAT_MASK)
                        ret = nf_nat_amanda(skb, ctinfo, off - dataoff,
                                            len, exp);
                else if (nf_ct_expect_related(exp) != 0)
                        ret = NF_DROP;
                nf_ct_expect_put(exp);
        }

out:
        return ret;
}

static const struct nf_conntrack_expect_policy amanda_exp_policy = {
        .max_expected           = 3,
        .timeout                = 180,
};

static struct nf_conntrack_helper amanda_helper[2] __read_mostly = {
        {
                .name                   = "amanda",
                .me                     = THIS_MODULE,
                .help                   = amanda_help,
                .tuple.src.l3num        = AF_INET,
                .tuple.src.u.udp.port   = __constant_htons(10080),
                .tuple.dst.protonum     = IPPROTO_UDP,
                .expect_policy          = &amanda_exp_policy,
        },
        {
                .name                   = "amanda",
                .me                     = THIS_MODULE,
                .help                   = amanda_help,
                .tuple.src.l3num        = AF_INET6,
                .tuple.src.u.udp.port   = __constant_htons(10080),
                .tuple.dst.protonum     = IPPROTO_UDP,
                .expect_policy          = &amanda_exp_policy,
        },
};

static void __exit nf_conntrack_amanda_fini(void)
{
        int i;

        nf_conntrack_helper_unregister(&amanda_helper[0]);
        nf_conntrack_helper_unregister(&amanda_helper[1]);
        for (i = 0; i < ARRAY_SIZE(search); i++)
                textsearch_destroy(search[i].ts);
}

static int __init nf_conntrack_amanda_init(void)
{
        int ret, i;

        for (i = 0; i < ARRAY_SIZE(search); i++) {
                search[i].ts = textsearch_prepare(ts_algo, search[i].string,
                                                  search[i].len,
                                                  GFP_KERNEL, TS_AUTOLOAD);
                if (IS_ERR(search[i].ts)) {
                        ret = PTR_ERR(search[i].ts);
                        goto err1;
                }
        }
        ret = nf_conntrack_helper_register(&amanda_helper[0]);
        if (ret < 0)
                goto err1;
        ret = nf_conntrack_helper_register(&amanda_helper[1]);
        if (ret < 0)
                goto err2;
        return 0;

err2:
        nf_conntrack_helper_unregister(&amanda_helper[0]);
err1:
        while (--i >= 0)
                textsearch_destroy(search[i].ts);

        return ret;
}

module_init(nf_conntrack_amanda_init);
module_exit(nf_conntrack_amanda_fini);

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