// SPDX-License-Identifier: GPL-2.0-or-later
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/* Amanda extension for IP connection tracking
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*
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* (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
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* based on HW's ip_conntrack_irc.c as well as other modules
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* (C) 2006 Patrick McHardy <kaber@trash.net>
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/textsearch.h>
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#include <linux/skbuff.h>
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#include <linux/in.h>
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#include <linux/udp.h>
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#include <linux/netfilter.h>
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#include <linux/gfp.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_ecache.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <linux/netfilter/nf_conntrack_amanda.h>
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static unsigned int master_timeout __read_mostly = 300;
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static char *ts_algo = "kmp";
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#define HELPER_NAME "amanda"
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MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
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MODULE_DESCRIPTION("Amanda connection tracking module");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ip_conntrack_amanda");
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MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
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module_param(master_timeout, uint, 0600);
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MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
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module_param(ts_algo, charp, 0400);
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MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
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unsigned int (*nf_nat_amanda_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)
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__read_mostly;
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EXPORT_SYMBOL_GPL(nf_nat_amanda_hook);
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enum amanda_strings {
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SEARCH_CONNECT,
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SEARCH_NEWLINE,
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SEARCH_DATA,
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SEARCH_MESG,
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SEARCH_INDEX,
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SEARCH_STATE,
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};
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static struct {
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const char *string;
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size_t len;
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struct ts_config *ts;
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} search[] __read_mostly = {
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[SEARCH_CONNECT] = {
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.string = "CONNECT ",
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.len = 8,
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},
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[SEARCH_NEWLINE] = {
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.string = "\n",
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.len = 1,
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},
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[SEARCH_DATA] = {
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.string = "DATA ",
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.len = 5,
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},
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[SEARCH_MESG] = {
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.string = "MESG ",
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.len = 5,
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},
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[SEARCH_INDEX] = {
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.string = "INDEX ",
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.len = 6,
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},
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[SEARCH_STATE] = {
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.string = "STATE ",
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.len = 6,
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},
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};
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static int amanda_help(struct sk_buff *skb,
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unsigned int protoff,
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struct nf_conn *ct,
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enum ip_conntrack_info ctinfo)
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{
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struct nf_conntrack_expect *exp;
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struct nf_conntrack_tuple *tuple;
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unsigned int dataoff, start, stop, off, i;
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char pbuf[sizeof("65535")], *tmp;
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u_int16_t len;
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__be16 port;
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int ret = NF_ACCEPT;
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typeof(nf_nat_amanda_hook) nf_nat_amanda;
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/* Only look at packets from the Amanda server */
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if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
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return NF_ACCEPT;
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/* increase the UDP timeout of the master connection as replies from
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* Amanda clients to the server can be quite delayed */
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nf_ct_refresh(ct, skb, master_timeout * HZ);
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/* No data? */
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dataoff = protoff + sizeof(struct udphdr);
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if (dataoff >= skb->len) {
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net_err_ratelimited("amanda_help: skblen = %u\n", skb->len);
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return NF_ACCEPT;
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}
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start = skb_find_text(skb, dataoff, skb->len,
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search[SEARCH_CONNECT].ts);
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if (start == UINT_MAX)
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goto out;
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start += dataoff + search[SEARCH_CONNECT].len;
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stop = skb_find_text(skb, start, skb->len,
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search[SEARCH_NEWLINE].ts);
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if (stop == UINT_MAX)
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goto out;
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stop += start;
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for (i = SEARCH_DATA; i <= SEARCH_STATE; i++) {
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off = skb_find_text(skb, start, stop, search[i].ts);
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if (off == UINT_MAX)
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continue;
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off += start + search[i].len;
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len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off);
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if (skb_copy_bits(skb, off, pbuf, len))
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break;
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pbuf[len] = '\0';
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port = htons(simple_strtoul(pbuf, &tmp, 10));
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len = tmp - pbuf;
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if (port == 0 || len > 5)
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break;
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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, "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[IP_CT_DIR_ORIGINAL].tuple;
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nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
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nf_ct_l3num(ct),
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&tuple->src.u3, &tuple->dst.u3,
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IPPROTO_TCP, NULL, &port);
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nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook);
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if (nf_nat_amanda && ct->status & IPS_NAT_MASK)
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ret = nf_nat_amanda(skb, ctinfo, protoff,
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off - dataoff, len, exp);
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else if (nf_ct_expect_related(exp, 0) != 0) {
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nf_ct_helper_log(skb, ct, "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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}
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out:
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return ret;
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}
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static const struct nf_conntrack_expect_policy amanda_exp_policy = {
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.max_expected = 4,
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.timeout = 180,
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};
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static struct nf_conntrack_helper amanda_helper[2] __read_mostly = {
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{
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.name = HELPER_NAME,
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.me = THIS_MODULE,
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.help = amanda_help,
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.tuple.src.l3num = AF_INET,
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.tuple.src.u.udp.port = cpu_to_be16(10080),
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.tuple.dst.protonum = IPPROTO_UDP,
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.expect_policy = &amanda_exp_policy,
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.nat_mod_name = NF_NAT_HELPER_NAME(HELPER_NAME),
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},
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{
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.name = "amanda",
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.me = THIS_MODULE,
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.help = amanda_help,
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.tuple.src.l3num = AF_INET6,
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.tuple.src.u.udp.port = cpu_to_be16(10080),
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.tuple.dst.protonum = IPPROTO_UDP,
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.expect_policy = &amanda_exp_policy,
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.nat_mod_name = NF_NAT_HELPER_NAME(HELPER_NAME),
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},
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};
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static void __exit nf_conntrack_amanda_fini(void)
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{
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int i;
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nf_conntrack_helpers_unregister(amanda_helper,
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ARRAY_SIZE(amanda_helper));
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for (i = 0; i < ARRAY_SIZE(search); i++)
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textsearch_destroy(search[i].ts);
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}
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static int __init nf_conntrack_amanda_init(void)
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{
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int ret, i;
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NF_CT_HELPER_BUILD_BUG_ON(0);
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for (i = 0; i < ARRAY_SIZE(search); i++) {
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search[i].ts = textsearch_prepare(ts_algo, search[i].string,
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search[i].len,
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GFP_KERNEL, TS_AUTOLOAD);
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if (IS_ERR(search[i].ts)) {
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ret = PTR_ERR(search[i].ts);
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goto err1;
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}
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}
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ret = nf_conntrack_helpers_register(amanda_helper,
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ARRAY_SIZE(amanda_helper));
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if (ret < 0)
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goto err1;
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return 0;
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err1:
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while (--i >= 0)
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textsearch_destroy(search[i].ts);
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return ret;
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}
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module_init(nf_conntrack_amanda_init);
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module_exit(nf_conntrack_amanda_fini);
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