[mirror_ubuntu-hirsute-kernel.git] / net / netfilter / nf_conntrack_helper.c

// SPDX-License-Identifier: GPL-2.0-only
/* Helper handling for netfilter. */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
 */

#include <linux/types.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/vmalloc.h>
#include <linux/stddef.h>
#include <linux/random.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <linux/rtnetlink.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_extend.h>
#include <net/netfilter/nf_log.h>

static DEFINE_MUTEX(nf_ct_helper_mutex);
struct hlist_head *nf_ct_helper_hash __read_mostly;
EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
unsigned int nf_ct_helper_hsize __read_mostly;
EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
static unsigned int nf_ct_helper_count __read_mostly;

static bool nf_ct_auto_assign_helper __read_mostly = false;
module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
MODULE_PARM_DESC(nf_conntrack_helper,
		 "Enable automatic conntrack helper assignment (default 0)");

static DEFINE_MUTEX(nf_ct_nat_helpers_mutex);
static struct list_head nf_ct_nat_helpers __read_mostly;

/* Stupid hash, but collision free for the default registrations of the
 * helpers currently in the kernel. */
static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
{
	return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
		(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
}

static struct nf_conntrack_helper *
__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
{
	struct nf_conntrack_helper *helper;
	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
	unsigned int h;

	if (!nf_ct_helper_count)
		return NULL;

	h = helper_hash(tuple);
	hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) {
		if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
			return helper;
	}
	return NULL;
}

struct nf_conntrack_helper *
__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
{
	struct nf_conntrack_helper *h;
	unsigned int i;

	for (i = 0; i < nf_ct_helper_hsize; i++) {
		hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) {
			if (strcmp(h->name, name))
				continue;

			if (h->tuple.src.l3num != NFPROTO_UNSPEC &&
			    h->tuple.src.l3num != l3num)
				continue;

			if (h->tuple.dst.protonum == protonum)
				return h;
		}
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);

struct nf_conntrack_helper *
nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
{
	struct nf_conntrack_helper *h;

	rcu_read_lock();

	h = __nf_conntrack_helper_find(name, l3num, protonum);
#ifdef CONFIG_MODULES
	if (h == NULL) {
		rcu_read_unlock();
		if (request_module("nfct-helper-%s", name) == 0) {
			rcu_read_lock();
			h = __nf_conntrack_helper_find(name, l3num, protonum);
		} else {
			return h;
		}
	}
#endif
	if (h != NULL && !try_module_get(h->me))
		h = NULL;
	if (h != NULL && !refcount_inc_not_zero(&h->refcnt)) {
		module_put(h->me);
		h = NULL;
	}

	rcu_read_unlock();

	return h;
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);

void nf_conntrack_helper_put(struct nf_conntrack_helper *helper)
{
	refcount_dec(&helper->refcnt);
	module_put(helper->me);
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_put);

static struct nf_conntrack_nat_helper *
nf_conntrack_nat_helper_find(const char *mod_name)
{
	struct nf_conntrack_nat_helper *cur;
	bool found = false;

	list_for_each_entry_rcu(cur, &nf_ct_nat_helpers, list) {
		if (!strcmp(cur->mod_name, mod_name)) {
			found = true;
			break;
		}
	}
	return found ? cur : NULL;
}

int
nf_nat_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
{
	struct nf_conntrack_helper *h;
	struct nf_conntrack_nat_helper *nat;
	char mod_name[NF_CT_HELPER_NAME_LEN];
	int ret = 0;

	rcu_read_lock();
	h = __nf_conntrack_helper_find(name, l3num, protonum);
	if (!h) {
		rcu_read_unlock();
		return -ENOENT;
	}

	nat = nf_conntrack_nat_helper_find(h->nat_mod_name);
	if (!nat) {
		snprintf(mod_name, sizeof(mod_name), "%s", h->nat_mod_name);
		rcu_read_unlock();
		request_module(mod_name);

		rcu_read_lock();
		nat = nf_conntrack_nat_helper_find(mod_name);
		if (!nat) {
			rcu_read_unlock();
			return -ENOENT;
		}
	}

	if (!try_module_get(nat->module))
		ret = -ENOENT;

	rcu_read_unlock();
	return ret;
}
EXPORT_SYMBOL_GPL(nf_nat_helper_try_module_get);

void nf_nat_helper_put(struct nf_conntrack_helper *helper)
{
	struct nf_conntrack_nat_helper *nat;

	nat = nf_conntrack_nat_helper_find(helper->nat_mod_name);
	if (WARN_ON_ONCE(!nat))
		return;

	module_put(nat->module);
}
EXPORT_SYMBOL_GPL(nf_nat_helper_put);

struct nf_conn_help *
nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
{
	struct nf_conn_help *help;

	help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
	if (help)
		INIT_HLIST_HEAD(&help->expectations);
	else
		pr_debug("failed to add helper extension area");
	return help;
}
EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);

static struct nf_conntrack_helper *
nf_ct_lookup_helper(struct nf_conn *ct, struct net *net)
{
	if (!net->ct.sysctl_auto_assign_helper) {
		if (net->ct.auto_assign_helper_warned)
			return NULL;
		if (!__nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple))
			return NULL;
		pr_info("nf_conntrack: default automatic helper assignment "
			"has been turned off for security reasons and CT-based "
			" firewall rule not found. Use the iptables CT target "
			"to attach helpers instead.\n");
		net->ct.auto_assign_helper_warned = 1;
		return NULL;
	}

	return __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
}


int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
			      gfp_t flags)
{
	struct nf_conntrack_helper *helper = NULL;
	struct nf_conn_help *help;
	struct net *net = nf_ct_net(ct);

	/* We already got a helper explicitly attached. The function
	 * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	 * the helper up again. Since now the user is in full control of
	 * making consistent helper configurations, skip this automatic
	 * re-lookup, otherwise we'll lose the helper.
	 */
	if (test_bit(IPS_HELPER_BIT, &ct->status))
		return 0;

	if (tmpl != NULL) {
		help = nfct_help(tmpl);
		if (help != NULL) {
			helper = help->helper;
			set_bit(IPS_HELPER_BIT, &ct->status);
		}
	}

	help = nfct_help(ct);

	if (helper == NULL) {
		helper = nf_ct_lookup_helper(ct, net);
		if (helper == NULL) {
			if (help)
				RCU_INIT_POINTER(help->helper, NULL);
			return 0;
		}
	}

	if (help == NULL) {
		help = nf_ct_helper_ext_add(ct, flags);
		if (help == NULL)
			return -ENOMEM;
	} else {
		/* We only allow helper re-assignment of the same sort since
		 * we cannot reallocate the helper extension area.
		 */
		struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);

		if (tmp && tmp->help != helper->help) {
			RCU_INIT_POINTER(help->helper, NULL);
			return 0;
		}
	}

	rcu_assign_pointer(help->helper, helper);

	return 0;
}
EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);

/* appropriate ct lock protecting must be taken by caller */
static int unhelp(struct nf_conn *ct, void *me)
{
	struct nf_conn_help *help = nfct_help(ct);

	if (help && rcu_dereference_raw(help->helper) == me) {
		nf_conntrack_event(IPCT_HELPER, ct);
		RCU_INIT_POINTER(help->helper, NULL);
	}

	/* We are not intended to delete this conntrack. */
	return 0;
}

void nf_ct_helper_destroy(struct nf_conn *ct)
{
	struct nf_conn_help *help = nfct_help(ct);
	struct nf_conntrack_helper *helper;

	if (help) {
		rcu_read_lock();
		helper = rcu_dereference(help->helper);
		if (helper && helper->destroy)
			helper->destroy(ct);
		rcu_read_unlock();
	}
}

static LIST_HEAD(nf_ct_helper_expectfn_list);

void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
{
	spin_lock_bh(&nf_conntrack_expect_lock);
	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
	spin_unlock_bh(&nf_conntrack_expect_lock);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);

void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
{
	spin_lock_bh(&nf_conntrack_expect_lock);
	list_del_rcu(&n->head);
	spin_unlock_bh(&nf_conntrack_expect_lock);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);

/* Caller should hold the rcu lock */
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_name(const char *name)
{
	struct nf_ct_helper_expectfn *cur;
	bool found = false;

	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
		if (!strcmp(cur->name, name)) {
			found = true;
			break;
		}
	}
	return found ? cur : NULL;
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);

/* Caller should hold the rcu lock */
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
{
	struct nf_ct_helper_expectfn *cur;
	bool found = false;

	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
		if (cur->expectfn == symbol) {
			found = true;
			break;
		}
	}
	return found ? cur : NULL;
}
EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);

__printf(3, 4)
void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
		      const char *fmt, ...)
{
	const struct nf_conn_help *help;
	const struct nf_conntrack_helper *helper;
	struct va_format vaf;
	va_list args;

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	/* Called from the helper function, this call never fails */
	help = nfct_help(ct);

	/* rcu_read_lock()ed by nf_hook_thresh */
	helper = rcu_dereference(help->helper);

	nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
		      "nf_ct_%s: dropping packet: %pV ", helper->name, &vaf);

	va_end(args);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_log);

int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
{
	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
	unsigned int h = helper_hash(&me->tuple);
	struct nf_conntrack_helper *cur;
	int ret = 0, i;

	BUG_ON(me->expect_policy == NULL);
	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);

	if (me->expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
		return -EINVAL;

	mutex_lock(&nf_ct_helper_mutex);
	for (i = 0; i < nf_ct_helper_hsize; i++) {
		hlist_for_each_entry(cur, &nf_ct_helper_hash[i], hnode) {
			if (!strcmp(cur->name, me->name) &&
			    (cur->tuple.src.l3num == NFPROTO_UNSPEC ||
			     cur->tuple.src.l3num == me->tuple.src.l3num) &&
			    cur->tuple.dst.protonum == me->tuple.dst.protonum) {
				ret = -EEXIST;
				goto out;
			}
		}
	}

	/* avoid unpredictable behaviour for auto_assign_helper */
	if (!(me->flags & NF_CT_HELPER_F_USERSPACE)) {
		hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
			if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple,
						     &mask)) {
				ret = -EEXIST;
				goto out;
			}
		}
	}
	refcount_set(&me->refcnt, 1);
	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
	nf_ct_helper_count++;
out:
	mutex_unlock(&nf_ct_helper_mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);

static bool expect_iter_me(struct nf_conntrack_expect *exp, void *data)
{
	struct nf_conn_help *help = nfct_help(exp->master);
	const struct nf_conntrack_helper *me = data;
	const struct nf_conntrack_helper *this;

	if (exp->helper == me)
		return true;

	this = rcu_dereference_protected(help->helper,
					 lockdep_is_held(&nf_conntrack_expect_lock));
	return this == me;
}

void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
{
	mutex_lock(&nf_ct_helper_mutex);
	hlist_del_rcu(&me->hnode);
	nf_ct_helper_count--;
	mutex_unlock(&nf_ct_helper_mutex);

	/* Make sure every nothing is still using the helper unless its a
	 * connection in the hash.
	 */
	synchronize_rcu();

	nf_ct_expect_iterate_destroy(expect_iter_me, NULL);
	nf_ct_iterate_destroy(unhelp, me);

	/* Maybe someone has gotten the helper already when unhelp above.
	 * So need to wait it.
	 */
	synchronize_rcu();
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);

void nf_ct_helper_init(struct nf_conntrack_helper *helper,
		       u16 l3num, u16 protonum, const char *name,
		       u16 default_port, u16 spec_port, u32 id,
		       const struct nf_conntrack_expect_policy *exp_pol,
		       u32 expect_class_max,
		       int (*help)(struct sk_buff *skb, unsigned int protoff,
				   struct nf_conn *ct,
				   enum ip_conntrack_info ctinfo),
		       int (*from_nlattr)(struct nlattr *attr,
					  struct nf_conn *ct),
		       struct module *module)
{
	helper->tuple.src.l3num = l3num;
	helper->tuple.dst.protonum = protonum;
	helper->tuple.src.u.all = htons(spec_port);
	helper->expect_policy = exp_pol;
	helper->expect_class_max = expect_class_max;
	helper->help = help;
	helper->from_nlattr = from_nlattr;
	helper->me = module;
	snprintf(helper->nat_mod_name, sizeof(helper->nat_mod_name),
		 NF_NAT_HELPER_PREFIX "%s", name);

	if (spec_port == default_port)
		snprintf(helper->name, sizeof(helper->name), "%s", name);
	else
		snprintf(helper->name, sizeof(helper->name), "%s-%u", name, id);
}
EXPORT_SYMBOL_GPL(nf_ct_helper_init);

int nf_conntrack_helpers_register(struct nf_conntrack_helper *helper,
				  unsigned int n)
{
	unsigned int i;
	int err = 0;

	for (i = 0; i < n; i++) {
		err = nf_conntrack_helper_register(&helper[i]);
		if (err < 0)
			goto err;
	}

	return err;
err:
	if (i > 0)
		nf_conntrack_helpers_unregister(helper, i);
	return err;
}
EXPORT_SYMBOL_GPL(nf_conntrack_helpers_register);

void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *helper,
				unsigned int n)
{
	while (n-- > 0)
		nf_conntrack_helper_unregister(&helper[n]);
}
EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister);

void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat)
{
	mutex_lock(&nf_ct_nat_helpers_mutex);
	list_add_rcu(&nat->list, &nf_ct_nat_helpers);
	mutex_unlock(&nf_ct_nat_helpers_mutex);
}
EXPORT_SYMBOL_GPL(nf_nat_helper_register);

void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat)
{
	mutex_lock(&nf_ct_nat_helpers_mutex);
	list_del_rcu(&nat->list);
	mutex_unlock(&nf_ct_nat_helpers_mutex);
}
EXPORT_SYMBOL_GPL(nf_nat_helper_unregister);

static const struct nf_ct_ext_type helper_extend = {
	.len	= sizeof(struct nf_conn_help),
	.align	= __alignof__(struct nf_conn_help),
	.id	= NF_CT_EXT_HELPER,
};

void nf_conntrack_helper_pernet_init(struct net *net)
{
	net->ct.auto_assign_helper_warned = false;
	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
}

int nf_conntrack_helper_init(void)
{
	int ret;
	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	nf_ct_helper_hash =
		nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	if (!nf_ct_helper_hash)
		return -ENOMEM;

	ret = nf_ct_extend_register(&helper_extend);
	if (ret < 0) {
		pr_err("nf_ct_helper: Unable to register helper extension.\n");
		goto out_extend;
	}

	INIT_LIST_HEAD(&nf_ct_nat_helpers);
	return 0;
out_extend:
	kvfree(nf_ct_helper_hash);
	return ret;
}

void nf_conntrack_helper_fini(void)
{
	nf_ct_extend_unregister(&helper_extend);
	kvfree(nf_ct_helper_hash);
}
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
7e5d03bb MJ	2	/* Helper handling for netfilter. */
	3
	4	/* (C) 1999-2001 Paul `Rusty' Russell
	5	* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
	6	* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
f229f6ce	7	* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
7e5d03bb MJ	8	*/
	9
	10	#include <linux/types.h>
	11	#include <linux/netfilter.h>
	12	#include <linux/module.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/vmalloc.h>
	15	#include <linux/stddef.h>
7e5d03bb MJ	16	#include <linux/random.h>
	17	#include <linux/err.h>
	18	#include <linux/kernel.h>
	19	#include <linux/netdevice.h>
2ba4cc31	20	#include <linux/rculist.h>
efb9a8c2	21	#include <linux/rtnetlink.h>
7e5d03bb	22
7e5d03bb	23	#include <net/netfilter/nf_conntrack.h>
605dcad6	24	#include <net/netfilter/nf_conntrack_l4proto.h>
7e5d03bb MJ	25	#include <net/netfilter/nf_conntrack_helper.h>
7e5d03bb MJ	26	#include <net/netfilter/nf_conntrack_core.h>
ceceae1b	27	#include <net/netfilter/nf_conntrack_extend.h>
b20ab9cc	28	#include <net/netfilter/nf_log.h>
7e5d03bb	29
58a3c9bb	30	static DEFINE_MUTEX(nf_ct_helper_mutex);
12f7a505 PNA	31	struct hlist_head *nf_ct_helper_hash __read_mostly;
	32	EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
	33	unsigned int nf_ct_helper_hsize __read_mostly;
	34	EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
b8a7fe6c	35	static unsigned int nf_ct_helper_count __read_mostly;
b8a7fe6c	36
3bb398d9	37	static bool nf_ct_auto_assign_helper __read_mostly = false;
a9006892 EL	38	module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
a9006892 EL	39	MODULE_PARM_DESC(nf_conntrack_helper,
3bb398d9	40	"Enable automatic conntrack helper assignment (default 0)");
a9006892	41
08010a21 FL	42	static DEFINE_MUTEX(nf_ct_nat_helpers_mutex);
	43	static struct list_head nf_ct_nat_helpers __read_mostly;
	44
b8a7fe6c PM	45	/* Stupid hash, but collision free for the default registrations of the
	46	* helpers currently in the kernel. */
	47	static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
	48	{
	49	return (((tuple->src.l3num << 8) \| tuple->dst.protonum) ^
a34c4589	50	(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
b8a7fe6c	51	}
7e5d03bb	52
226c0c0e	53	static struct nf_conntrack_helper *
7e5d03bb MJ	54	__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
7e5d03bb MJ	55	{
b8a7fe6c	56	struct nf_conntrack_helper *helper;
d4156e8c	57	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
b8a7fe6c	58	unsigned int h;
7e5d03bb	59
b8a7fe6c PM	60	if (!nf_ct_helper_count)
	61	return NULL;
	62
	63	h = helper_hash(tuple);
b67bfe0d	64	hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) {
b8a7fe6c PM	65	if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
b8a7fe6c PM	66	return helper;
7e5d03bb MJ	67	}
	68	return NULL;
	69	}
7e5d03bb MJ	70
7e5d03bb MJ	71	struct nf_conntrack_helper *
794e6871	72	__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
7e5d03bb MJ	73	{
7e5d03bb MJ	74	struct nf_conntrack_helper *h;
b8a7fe6c	75	unsigned int i;
7e5d03bb	76
b8a7fe6c	77	for (i = 0; i < nf_ct_helper_hsize; i++) {
b67bfe0d	78	hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) {
6114cc51 FW	79	if (strcmp(h->name, name))
	80	continue;
	81
	82	if (h->tuple.src.l3num != NFPROTO_UNSPEC &&
	83	h->tuple.src.l3num != l3num)
	84	continue;
	85
	86	if (h->tuple.dst.protonum == protonum)
b8a7fe6c PM	87	return h;
b8a7fe6c PM	88	}
7e5d03bb	89	}
7e5d03bb MJ	90	return NULL;
7e5d03bb MJ	91	}
794e6871	92	EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
7e5d03bb	93
84f3bb9a PM	94	struct nf_conntrack_helper *
	95	nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	96	{
	97	struct nf_conntrack_helper *h;
	98
8b5995d0 GF	99	rcu_read_lock();
8b5995d0 GF	100
84f3bb9a PM	101	h = __nf_conntrack_helper_find(name, l3num, protonum);
	102	#ifdef CONFIG_MODULES
	103	if (h == NULL) {
8b5995d0 GF	104	rcu_read_unlock();
	105	if (request_module("nfct-helper-%s", name) == 0) {
	106	rcu_read_lock();
84f3bb9a	107	h = __nf_conntrack_helper_find(name, l3num, protonum);
8b5995d0 GF	108	} else {
	109	return h;
	110	}
84f3bb9a PM	111	}
	112	#endif
	113	if (h != NULL && !try_module_get(h->me))
	114	h = NULL;
9338d7b4 LZ	115	if (h != NULL && !refcount_inc_not_zero(&h->refcnt)) {
	116	module_put(h->me);
	117	h = NULL;
	118	}
84f3bb9a	119
8b5995d0 GF	120	rcu_read_unlock();
8b5995d0 GF	121
84f3bb9a PM	122	return h;
	123	}
	124	EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
	125
d91fc59c LZ	126	void nf_conntrack_helper_put(struct nf_conntrack_helper *helper)
d91fc59c LZ	127	{
9338d7b4	128	refcount_dec(&helper->refcnt);
d91fc59c LZ	129	module_put(helper->me);
	130	}
	131	EXPORT_SYMBOL_GPL(nf_conntrack_helper_put);
	132
08010a21 FL	133	static struct nf_conntrack_nat_helper *
	134	nf_conntrack_nat_helper_find(const char *mod_name)
	135	{
	136	struct nf_conntrack_nat_helper *cur;
	137	bool found = false;
	138
	139	list_for_each_entry_rcu(cur, &nf_ct_nat_helpers, list) {
	140	if (!strcmp(cur->mod_name, mod_name)) {
	141	found = true;
	142	break;
	143	}
	144	}
	145	return found ? cur : NULL;
	146	}
	147
	148	int
	149	nf_nat_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	150	{
	151	struct nf_conntrack_helper *h;
	152	struct nf_conntrack_nat_helper *nat;
	153	char mod_name[NF_CT_HELPER_NAME_LEN];
	154	int ret = 0;
	155
	156	rcu_read_lock();
	157	h = __nf_conntrack_helper_find(name, l3num, protonum);
	158	if (!h) {
	159	rcu_read_unlock();
	160	return -ENOENT;
	161	}
	162
	163	nat = nf_conntrack_nat_helper_find(h->nat_mod_name);
	164	if (!nat) {
	165	snprintf(mod_name, sizeof(mod_name), "%s", h->nat_mod_name);
	166	rcu_read_unlock();
	167	request_module(mod_name);
	168
	169	rcu_read_lock();
	170	nat = nf_conntrack_nat_helper_find(mod_name);
	171	if (!nat) {
	172	rcu_read_unlock();
	173	return -ENOENT;
	174	}
	175	}
	176
	177	if (!try_module_get(nat->module))
	178	ret = -ENOENT;
	179
	180	rcu_read_unlock();
	181	return ret;
	182	}
	183	EXPORT_SYMBOL_GPL(nf_nat_helper_try_module_get);
	184
	185	void nf_nat_helper_put(struct nf_conntrack_helper *helper)
	186	{
	187	struct nf_conntrack_nat_helper *nat;
	188
	189	nat = nf_conntrack_nat_helper_find(helper->nat_mod_name);
	190	if (WARN_ON_ONCE(!nat))
	191	return;
	192
	193	module_put(nat->module);
	194	}
	195	EXPORT_SYMBOL_GPL(nf_nat_helper_put);
	196
1afc5679	197	struct nf_conn_help *
440534d3	198	nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
b560580a PM	199	{
	200	struct nf_conn_help *help;
	201
9f0f3ebe	202	help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
b560580a PM	203	if (help)
	204	INIT_HLIST_HEAD(&help->expectations);
	205	else
	206	pr_debug("failed to add helper extension area");
	207	return help;
	208	}
	209	EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
	210
dfe75ff8 JK	211	static struct nf_conntrack_helper *
	212	nf_ct_lookup_helper(struct nf_conn ct, struct net net)
	213	{
	214	if (!net->ct.sysctl_auto_assign_helper) {
	215	if (net->ct.auto_assign_helper_warned)
	216	return NULL;
	217	if (!__nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple))
	218	return NULL;
	219	pr_info("nf_conntrack: default automatic helper assignment "
	220	"has been turned off for security reasons and CT-based "
	221	" firewall rule not found. Use the iptables CT target "
	222	"to attach helpers instead.\n");
	223	net->ct.auto_assign_helper_warned = 1;
	224	return NULL;
	225	}
	226
	227	return __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
	228	}
	229
	230
b2a15a60 PM	231	int __nf_ct_try_assign_helper(struct nf_conn ct, struct nf_conn tmpl,
b2a15a60 PM	232	gfp_t flags)
226c0c0e	233	{
b2a15a60 PM	234	struct nf_conntrack_helper *helper = NULL;
b2a15a60 PM	235	struct nf_conn_help *help;
a9006892	236	struct net *net = nf_ct_net(ct);
226c0c0e	237
6714cf54 PNA	238	/* We already got a helper explicitly attached. The function
	239	* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	240	* the helper up again. Since now the user is in full control of
	241	* making consistent helper configurations, skip this automatic
	242	* re-lookup, otherwise we'll lose the helper.
	243	*/
	244	if (test_bit(IPS_HELPER_BIT, &ct->status))
	245	return 0;
	246
b2a15a60 PM	247	if (tmpl != NULL) {
b2a15a60 PM	248	help = nfct_help(tmpl);
6714cf54	249	if (help != NULL) {
b2a15a60	250	helper = help->helper;
6714cf54 PNA	251	set_bit(IPS_HELPER_BIT, &ct->status);
6714cf54 PNA	252	}
b2a15a60 PM	253	}
	254
	255	help = nfct_help(ct);
a9006892	256
226c0c0e	257	if (helper == NULL) {
dfe75ff8 JK	258	helper = nf_ct_lookup_helper(ct, net);
	259	if (helper == NULL) {
	260	if (help)
	261	RCU_INIT_POINTER(help->helper, NULL);
	262	return 0;
	263	}
226c0c0e PNA	264	}
	265
	266	if (help == NULL) {
440534d3	267	help = nf_ct_helper_ext_add(ct, flags);
cf71c03e PN	268	if (help == NULL)
cf71c03e PN	269	return -ENOMEM;
226c0c0e	270	} else {
32f53760 PNA	271	/* We only allow helper re-assignment of the same sort since
	272	* we cannot reallocate the helper extension area.
	273	*/
6e2f0aa8 FW	274	struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
	275
	276	if (tmp && tmp->help != helper->help) {
32f53760	277	RCU_INIT_POINTER(help->helper, NULL);
cf71c03e	278	return 0;
32f53760	279	}
226c0c0e PNA	280	}
226c0c0e PNA	281
cf778b00	282	rcu_assign_pointer(help->helper, helper);
cf71c03e PN	283
cf71c03e PN	284	return 0;
226c0c0e PNA	285	}
	286	EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
	287
01cfa0a4	288	/* appropriate ct lock protecting must be taken by caller */
ff1acc49	289	static int unhelp(struct nf_conn ct, void me)
7e5d03bb	290	{
7e5d03bb MJ	291	struct nf_conn_help *help = nfct_help(ct);
7e5d03bb MJ	292
ca7433df	293	if (help && rcu_dereference_raw(help->helper) == me) {
7e5d03bb	294	nf_conntrack_event(IPCT_HELPER, ct);
a9b3cd7f	295	RCU_INIT_POINTER(help->helper, NULL);
7e5d03bb	296	}
ff1acc49 LZ	297
ff1acc49 LZ	298	/* We are not intended to delete this conntrack. */
7e5d03bb MJ	299	return 0;
	300	}
	301
9858a3ae PNA	302	void nf_ct_helper_destroy(struct nf_conn *ct)
	303	{
	304	struct nf_conn_help *help = nfct_help(ct);
	305	struct nf_conntrack_helper *helper;
	306
	307	if (help) {
	308	rcu_read_lock();
	309	helper = rcu_dereference(help->helper);
	310	if (helper && helper->destroy)
	311	helper->destroy(ct);
	312	rcu_read_unlock();
	313	}
	314	}
	315
544d5c7d PNA	316	static LIST_HEAD(nf_ct_helper_expectfn_list);
	317
	318	void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
	319	{
ca7433df	320	spin_lock_bh(&nf_conntrack_expect_lock);
544d5c7d	321	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
ca7433df	322	spin_unlock_bh(&nf_conntrack_expect_lock);
544d5c7d PNA	323	}
	324	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
	325
	326	void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
	327	{
ca7433df	328	spin_lock_bh(&nf_conntrack_expect_lock);
544d5c7d	329	list_del_rcu(&n->head);
ca7433df	330	spin_unlock_bh(&nf_conntrack_expect_lock);
544d5c7d PNA	331	}
	332	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
	333
8b5995d0	334	/* Caller should hold the rcu lock */
544d5c7d PNA	335	struct nf_ct_helper_expectfn *
	336	nf_ct_helper_expectfn_find_by_name(const char *name)
	337	{
	338	struct nf_ct_helper_expectfn *cur;
	339	bool found = false;
	340
544d5c7d PNA	341	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	342	if (!strcmp(cur->name, name)) {
	343	found = true;
	344	break;
	345	}
	346	}
544d5c7d PNA	347	return found ? cur : NULL;
	348	}
	349	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
	350
8b5995d0	351	/* Caller should hold the rcu lock */
544d5c7d PNA	352	struct nf_ct_helper_expectfn *
	353	nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
	354	{
	355	struct nf_ct_helper_expectfn *cur;
	356	bool found = false;
	357
544d5c7d PNA	358	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	359	if (cur->expectfn == symbol) {
	360	found = true;
	361	break;
	362	}
	363	}
544d5c7d PNA	364	return found ? cur : NULL;
	365	}
	366	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
	367
b20ab9cc PNA	368	__printf(3, 4)
	369	void nf_ct_helper_log(struct sk_buff skb, const struct nf_conn ct,
	370	const char *fmt, ...)
	371	{
	372	const struct nf_conn_help *help;
	373	const struct nf_conntrack_helper *helper;
f9caed59 JP	374	struct va_format vaf;
	375	va_list args;
	376
	377	va_start(args, fmt);
	378
	379	vaf.fmt = fmt;
	380	vaf.va = &args;
b20ab9cc PNA	381
	382	/* Called from the helper function, this call never fails */
	383	help = nfct_help(ct);
	384
e2361cb9	385	/* rcu_read_lock()ed by nf_hook_thresh */
b20ab9cc PNA	386	helper = rcu_dereference(help->helper);
b20ab9cc PNA	387
30e0c6a6	388	nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
f9caed59 JP	389	"nf_ct_%s: dropping packet: %pV ", helper->name, &vaf);
	390
	391	va_end(args);
b20ab9cc PNA	392	}
	393	EXPORT_SYMBOL_GPL(nf_ct_helper_log);
	394
7e5d03bb MJ	395	int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
7e5d03bb MJ	396	{
893e093c	397	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
b8a7fe6c	398	unsigned int h = helper_hash(&me->tuple);
893e093c	399	struct nf_conntrack_helper *cur;
66e5a6b1	400	int ret = 0, i;
b8a7fe6c	401
6002f266 PM	402	BUG_ON(me->expect_policy == NULL);
6002f266 PM	403	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
af9d32ad	404	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
7e5d03bb	405
92f73221 GF	406	if (me->expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
	407	return -EINVAL;
	408
58a3c9bb	409	mutex_lock(&nf_ct_helper_mutex);
66e5a6b1 LZ	410	for (i = 0; i < nf_ct_helper_hsize; i++) {
	411	hlist_for_each_entry(cur, &nf_ct_helper_hash[i], hnode) {
	412	if (!strcmp(cur->name, me->name) &&
	413	(cur->tuple.src.l3num == NFPROTO_UNSPEC \|\|
	414	cur->tuple.src.l3num == me->tuple.src.l3num) &&
	415	cur->tuple.dst.protonum == me->tuple.dst.protonum) {
	416	ret = -EEXIST;
	417	goto out;
	418	}
	419	}
	420	}
	421
	422	/* avoid unpredictable behaviour for auto_assign_helper */
	423	if (!(me->flags & NF_CT_HELPER_F_USERSPACE)) {
	424	hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
	425	if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple,
	426	&mask)) {
	427	ret = -EEXIST;
	428	goto out;
	429	}
12f7a505 PNA	430	}
12f7a505 PNA	431	}
9338d7b4	432	refcount_set(&me->refcnt, 1);
58a3c9bb	433	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
b8a7fe6c	434	nf_ct_helper_count++;
12f7a505	435	out:
58a3c9bb	436	mutex_unlock(&nf_ct_helper_mutex);
12f7a505	437	return ret;
7e5d03bb	438	}
13b18339	439	EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
7e5d03bb	440
ac7b8483	441	static bool expect_iter_me(struct nf_conntrack_expect exp, void data)
7e5d03bb	442	{
ac7b8483 FW	443	struct nf_conn_help *help = nfct_help(exp->master);
	444	const struct nf_conntrack_helper *me = data;
	445	const struct nf_conntrack_helper *this;
	446
	447	if (exp->helper == me)
	448	return true;
436a850d	449
ac7b8483 FW	450	this = rcu_dereference_protected(help->helper,
	451	lockdep_is_held(&nf_conntrack_expect_lock));
	452	return this == me;
	453	}
	454
	455	void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
	456	{
436a850d FW	457	mutex_lock(&nf_ct_helper_mutex);
	458	hlist_del_rcu(&me->hnode);
	459	nf_ct_helper_count--;
	460	mutex_unlock(&nf_ct_helper_mutex);
	461
	462	/* Make sure every nothing is still using the helper unless its a
	463	* connection in the hash.
	464	*/
	465	synchronize_rcu();
7e5d03bb	466
ac7b8483	467	nf_ct_expect_iterate_destroy(expect_iter_me, NULL);
ff1acc49	468	nf_ct_iterate_destroy(unhelp, me);
ad9852af GF	469
	470	/* Maybe someone has gotten the helper already when unhelp above.
	471	* So need to wait it.
	472	*/
	473	synchronize_rcu();
68047937	474	}
13b18339	475	EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
ceceae1b	476
82de0be6 GF	477	void nf_ct_helper_init(struct nf_conntrack_helper *helper,
	478	u16 l3num, u16 protonum, const char *name,
	479	u16 default_port, u16 spec_port, u32 id,
	480	const struct nf_conntrack_expect_policy *exp_pol,
9f0f3ebe	481	u32 expect_class_max,
82de0be6 GF	482	int (help)(struct sk_buff skb, unsigned int protoff,
	483	struct nf_conn *ct,
	484	enum ip_conntrack_info ctinfo),
	485	int (from_nlattr)(struct nlattr attr,
	486	struct nf_conn *ct),
	487	struct module *module)
	488	{
	489	helper->tuple.src.l3num = l3num;
	490	helper->tuple.dst.protonum = protonum;
	491	helper->tuple.src.u.all = htons(spec_port);
	492	helper->expect_policy = exp_pol;
	493	helper->expect_class_max = expect_class_max;
82de0be6 GF	494	helper->help = help;
	495	helper->from_nlattr = from_nlattr;
	496	helper->me = module;
08010a21 FL	497	snprintf(helper->nat_mod_name, sizeof(helper->nat_mod_name),
08010a21 FL	498	NF_NAT_HELPER_PREFIX "%s", name);
82de0be6 GF	499
	500	if (spec_port == default_port)
	501	snprintf(helper->name, sizeof(helper->name), "%s", name);
	502	else
	503	snprintf(helper->name, sizeof(helper->name), "%s-%u", name, id);
	504	}
	505	EXPORT_SYMBOL_GPL(nf_ct_helper_init);
	506
	507	int nf_conntrack_helpers_register(struct nf_conntrack_helper *helper,
	508	unsigned int n)
	509	{
	510	unsigned int i;
	511	int err = 0;
	512
	513	for (i = 0; i < n; i++) {
	514	err = nf_conntrack_helper_register(&helper[i]);
	515	if (err < 0)
	516	goto err;
	517	}
	518
	519	return err;
	520	err:
	521	if (i > 0)
	522	nf_conntrack_helpers_unregister(helper, i);
	523	return err;
	524	}
	525	EXPORT_SYMBOL_GPL(nf_conntrack_helpers_register);
	526
	527	void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *helper,
	528	unsigned int n)
	529	{
	530	while (n-- > 0)
	531	nf_conntrack_helper_unregister(&helper[n]);
	532	}
	533	EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister);
	534
08010a21 FL	535	void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat)
	536	{
	537	mutex_lock(&nf_ct_nat_helpers_mutex);
	538	list_add_rcu(&nat->list, &nf_ct_nat_helpers);
	539	mutex_unlock(&nf_ct_nat_helpers_mutex);
	540	}
	541	EXPORT_SYMBOL_GPL(nf_nat_helper_register);
	542
	543	void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat)
	544	{
	545	mutex_lock(&nf_ct_nat_helpers_mutex);
	546	list_del_rcu(&nat->list);
	547	mutex_unlock(&nf_ct_nat_helpers_mutex);
	548	}
	549	EXPORT_SYMBOL_GPL(nf_nat_helper_unregister);
	550
23f671a1	551	static const struct nf_ct_ext_type helper_extend = {
ceceae1b YK	552	.len = sizeof(struct nf_conn_help),
	553	.align = __alignof__(struct nf_conn_help),
	554	.id = NF_CT_EXT_HELPER,
	555	};
	556
fc3893fd	557	void nf_conntrack_helper_pernet_init(struct net *net)
ceceae1b	558	{
a9006892 EL	559	net->ct.auto_assign_helper_warned = false;
a9006892 EL	560	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
5e615b22	561	}
a9006892	562
5e615b22 G	563	int nf_conntrack_helper_init(void)
	564	{
	565	int ret;
	566	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	567	nf_ct_helper_hash =
	568	nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	569	if (!nf_ct_helper_hash)
	570	return -ENOMEM;
	571
	572	ret = nf_ct_extend_register(&helper_extend);
	573	if (ret < 0) {
	574	pr_err("nf_ct_helper: Unable to register helper extension.\n");
	575	goto out_extend;
a9006892 EL	576	}
a9006892 EL	577
08010a21	578	INIT_LIST_HEAD(&nf_ct_nat_helpers);
b8a7fe6c	579	return 0;
5e615b22	580	out_extend:
285189c7	581	kvfree(nf_ct_helper_hash);
5e615b22	582	return ret;
ceceae1b YK	583	}
ceceae1b YK	584
5e615b22	585	void nf_conntrack_helper_fini(void)
ceceae1b	586	{
5e615b22	587	nf_ct_extend_unregister(&helper_extend);
285189c7	588	kvfree(nf_ct_helper_hash);
ceceae1b	589	}