01cfa0a4ed
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
503 lines
13 KiB
C
503 lines
13 KiB
C
/* Helper handling for netfilter. */
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
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* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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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 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/netfilter.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/vmalloc.h>
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#include <linux/stddef.h>
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#include <linux/random.h>
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#include <linux/err.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/rculist.h>
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#include <linux/rtnetlink.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_l3proto.h>
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#include <net/netfilter/nf_conntrack_l4proto.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_extend.h>
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#include <net/netfilter/nf_log.h>
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static DEFINE_MUTEX(nf_ct_helper_mutex);
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struct hlist_head *nf_ct_helper_hash __read_mostly;
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EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
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unsigned int nf_ct_helper_hsize __read_mostly;
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EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
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static unsigned int nf_ct_helper_count __read_mostly;
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static bool nf_ct_auto_assign_helper __read_mostly = true;
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module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
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MODULE_PARM_DESC(nf_conntrack_helper,
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"Enable automatic conntrack helper assignment (default 1)");
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#ifdef CONFIG_SYSCTL
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static struct ctl_table helper_sysctl_table[] = {
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{
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.procname = "nf_conntrack_helper",
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.data = &init_net.ct.sysctl_auto_assign_helper,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = proc_dointvec,
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},
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{}
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};
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static int nf_conntrack_helper_init_sysctl(struct net *net)
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{
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struct ctl_table *table;
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table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
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GFP_KERNEL);
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if (!table)
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goto out;
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table[0].data = &net->ct.sysctl_auto_assign_helper;
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/* Don't export sysctls to unprivileged users */
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if (net->user_ns != &init_user_ns)
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table[0].procname = NULL;
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net->ct.helper_sysctl_header =
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register_net_sysctl(net, "net/netfilter", table);
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if (!net->ct.helper_sysctl_header) {
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pr_err("nf_conntrack_helper: can't register to sysctl.\n");
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goto out_register;
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}
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return 0;
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out_register:
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kfree(table);
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out:
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return -ENOMEM;
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}
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static void nf_conntrack_helper_fini_sysctl(struct net *net)
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{
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struct ctl_table *table;
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table = net->ct.helper_sysctl_header->ctl_table_arg;
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unregister_net_sysctl_table(net->ct.helper_sysctl_header);
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kfree(table);
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}
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#else
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static int nf_conntrack_helper_init_sysctl(struct net *net)
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{
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return 0;
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}
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static void nf_conntrack_helper_fini_sysctl(struct net *net)
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{
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}
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#endif /* CONFIG_SYSCTL */
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/* Stupid hash, but collision free for the default registrations of the
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* helpers currently in the kernel. */
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static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
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{
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return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
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(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
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}
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static struct nf_conntrack_helper *
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__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
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{
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struct nf_conntrack_helper *helper;
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struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
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unsigned int h;
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if (!nf_ct_helper_count)
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return NULL;
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h = helper_hash(tuple);
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hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) {
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if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
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return helper;
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}
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return NULL;
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}
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struct nf_conntrack_helper *
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__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
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{
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struct nf_conntrack_helper *h;
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unsigned int i;
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for (i = 0; i < nf_ct_helper_hsize; i++) {
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hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) {
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if (!strcmp(h->name, name) &&
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h->tuple.src.l3num == l3num &&
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h->tuple.dst.protonum == protonum)
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return h;
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}
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}
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return NULL;
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}
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EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
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struct nf_conntrack_helper *
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nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
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{
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struct nf_conntrack_helper *h;
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h = __nf_conntrack_helper_find(name, l3num, protonum);
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#ifdef CONFIG_MODULES
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if (h == NULL) {
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if (request_module("nfct-helper-%s", name) == 0)
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h = __nf_conntrack_helper_find(name, l3num, protonum);
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}
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#endif
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if (h != NULL && !try_module_get(h->me))
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h = NULL;
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return h;
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}
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EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
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struct nf_conn_help *
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nf_ct_helper_ext_add(struct nf_conn *ct,
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struct nf_conntrack_helper *helper, gfp_t gfp)
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{
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struct nf_conn_help *help;
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help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
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helper->data_len, gfp);
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if (help)
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INIT_HLIST_HEAD(&help->expectations);
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else
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pr_debug("failed to add helper extension area");
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return help;
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}
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EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
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int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
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gfp_t flags)
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{
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struct nf_conntrack_helper *helper = NULL;
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struct nf_conn_help *help;
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struct net *net = nf_ct_net(ct);
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int ret = 0;
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/* We already got a helper explicitly attached. The function
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* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
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* the helper up again. Since now the user is in full control of
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* making consistent helper configurations, skip this automatic
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* re-lookup, otherwise we'll lose the helper.
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*/
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if (test_bit(IPS_HELPER_BIT, &ct->status))
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return 0;
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if (tmpl != NULL) {
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help = nfct_help(tmpl);
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if (help != NULL) {
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helper = help->helper;
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set_bit(IPS_HELPER_BIT, &ct->status);
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}
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}
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help = nfct_help(ct);
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if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
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helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
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if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
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pr_info("nf_conntrack: automatic helper "
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"assignment is deprecated and it will "
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"be removed soon. Use the iptables CT target "
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"to attach helpers instead.\n");
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net->ct.auto_assign_helper_warned = true;
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}
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}
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if (helper == NULL) {
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if (help)
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RCU_INIT_POINTER(help->helper, NULL);
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goto out;
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}
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if (help == NULL) {
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help = nf_ct_helper_ext_add(ct, helper, flags);
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if (help == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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} else {
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/* We only allow helper re-assignment of the same sort since
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* we cannot reallocate the helper extension area.
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*/
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struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
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if (tmp && tmp->help != helper->help) {
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RCU_INIT_POINTER(help->helper, NULL);
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goto out;
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}
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}
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rcu_assign_pointer(help->helper, helper);
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out:
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return ret;
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}
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EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
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/* appropriate ct lock protecting must be taken by caller */
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static inline int unhelp(struct nf_conntrack_tuple_hash *i,
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const struct nf_conntrack_helper *me)
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{
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struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
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struct nf_conn_help *help = nfct_help(ct);
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if (help && rcu_dereference_raw(help->helper) == me) {
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nf_conntrack_event(IPCT_HELPER, ct);
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RCU_INIT_POINTER(help->helper, NULL);
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}
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return 0;
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}
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void nf_ct_helper_destroy(struct nf_conn *ct)
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{
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struct nf_conn_help *help = nfct_help(ct);
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struct nf_conntrack_helper *helper;
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if (help) {
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rcu_read_lock();
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helper = rcu_dereference(help->helper);
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if (helper && helper->destroy)
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helper->destroy(ct);
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rcu_read_unlock();
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}
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}
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static LIST_HEAD(nf_ct_helper_expectfn_list);
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void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
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{
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spin_lock_bh(&nf_conntrack_expect_lock);
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list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
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spin_unlock_bh(&nf_conntrack_expect_lock);
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}
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EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
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void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
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{
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spin_lock_bh(&nf_conntrack_expect_lock);
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list_del_rcu(&n->head);
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spin_unlock_bh(&nf_conntrack_expect_lock);
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}
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EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
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struct nf_ct_helper_expectfn *
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nf_ct_helper_expectfn_find_by_name(const char *name)
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{
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struct nf_ct_helper_expectfn *cur;
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bool found = false;
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rcu_read_lock();
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list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
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if (!strcmp(cur->name, name)) {
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found = true;
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break;
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}
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}
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rcu_read_unlock();
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return found ? cur : NULL;
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}
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EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
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struct nf_ct_helper_expectfn *
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nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
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{
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struct nf_ct_helper_expectfn *cur;
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bool found = false;
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rcu_read_lock();
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list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
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if (cur->expectfn == symbol) {
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found = true;
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break;
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}
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}
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rcu_read_unlock();
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return found ? cur : NULL;
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}
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EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
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__printf(3, 4)
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void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
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const char *fmt, ...)
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{
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const struct nf_conn_help *help;
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const struct nf_conntrack_helper *helper;
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struct va_format vaf;
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va_list args;
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va_start(args, fmt);
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vaf.fmt = fmt;
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vaf.va = &args;
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/* Called from the helper function, this call never fails */
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help = nfct_help(ct);
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/* rcu_read_lock()ed by nf_hook_slow */
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helper = rcu_dereference(help->helper);
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nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
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"nf_ct_%s: dropping packet: %pV ", helper->name, &vaf);
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va_end(args);
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}
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EXPORT_SYMBOL_GPL(nf_ct_helper_log);
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int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
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{
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int ret = 0;
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struct nf_conntrack_helper *cur;
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unsigned int h = helper_hash(&me->tuple);
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BUG_ON(me->expect_policy == NULL);
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BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
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BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
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mutex_lock(&nf_ct_helper_mutex);
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hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
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if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
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cur->tuple.src.l3num == me->tuple.src.l3num &&
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cur->tuple.dst.protonum == me->tuple.dst.protonum) {
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ret = -EEXIST;
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goto out;
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}
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}
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hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
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nf_ct_helper_count++;
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out:
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mutex_unlock(&nf_ct_helper_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
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static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
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struct net *net)
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{
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struct nf_conntrack_tuple_hash *h;
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struct nf_conntrack_expect *exp;
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const struct hlist_node *next;
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const struct hlist_nulls_node *nn;
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unsigned int i;
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int cpu;
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/* Get rid of expectations */
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spin_lock_bh(&nf_conntrack_expect_lock);
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for (i = 0; i < nf_ct_expect_hsize; i++) {
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hlist_for_each_entry_safe(exp, next,
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&net->ct.expect_hash[i], hnode) {
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struct nf_conn_help *help = nfct_help(exp->master);
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if ((rcu_dereference_protected(
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help->helper,
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lockdep_is_held(&nf_conntrack_expect_lock)
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) == me || exp->helper == me) &&
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del_timer(&exp->timeout)) {
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nf_ct_unlink_expect(exp);
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nf_ct_expect_put(exp);
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}
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}
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}
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spin_unlock_bh(&nf_conntrack_expect_lock);
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/* Get rid of expecteds, set helpers to NULL. */
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for_each_possible_cpu(cpu) {
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struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
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spin_lock_bh(&pcpu->lock);
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hlist_nulls_for_each_entry(h, nn, &pcpu->unconfirmed, hnnode)
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unhelp(h, me);
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spin_unlock_bh(&pcpu->lock);
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}
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local_bh_disable();
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for (i = 0; i < net->ct.htable_size; i++) {
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spin_lock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]);
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if (i < net->ct.htable_size) {
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hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
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unhelp(h, me);
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}
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spin_unlock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]);
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}
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local_bh_enable();
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}
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void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
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{
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struct net *net;
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mutex_lock(&nf_ct_helper_mutex);
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hlist_del_rcu(&me->hnode);
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nf_ct_helper_count--;
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mutex_unlock(&nf_ct_helper_mutex);
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/* Make sure every nothing is still using the helper unless its a
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* connection in the hash.
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*/
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synchronize_rcu();
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rtnl_lock();
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for_each_net(net)
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__nf_conntrack_helper_unregister(me, net);
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rtnl_unlock();
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}
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EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
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static struct nf_ct_ext_type helper_extend __read_mostly = {
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.len = sizeof(struct nf_conn_help),
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.align = __alignof__(struct nf_conn_help),
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.id = NF_CT_EXT_HELPER,
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};
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int nf_conntrack_helper_pernet_init(struct net *net)
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{
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net->ct.auto_assign_helper_warned = false;
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net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
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return nf_conntrack_helper_init_sysctl(net);
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}
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void nf_conntrack_helper_pernet_fini(struct net *net)
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{
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nf_conntrack_helper_fini_sysctl(net);
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}
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int nf_conntrack_helper_init(void)
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{
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int ret;
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nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
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nf_ct_helper_hash =
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nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
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if (!nf_ct_helper_hash)
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return -ENOMEM;
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ret = nf_ct_extend_register(&helper_extend);
|
|
if (ret < 0) {
|
|
pr_err("nf_ct_helper: Unable to register helper extension.\n");
|
|
goto out_extend;
|
|
}
|
|
|
|
return 0;
|
|
out_extend:
|
|
nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
|
|
return ret;
|
|
}
|
|
|
|
void nf_conntrack_helper_fini(void)
|
|
{
|
|
nf_ct_extend_unregister(&helper_extend);
|
|
nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
|
|
}
|