[linux-2.6-block.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_core.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_extend.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_l4proto.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>
7e5d03bb	24	#include <net/netfilter/nf_conntrack_core.h>
40d102cd	25	#include <net/netfilter/nf_conntrack_ecache.h>
ceceae1b	26	#include <net/netfilter/nf_conntrack_extend.h>
40d102cd JS	27	#include <net/netfilter/nf_conntrack_helper.h>
40d102cd JS	28	#include <net/netfilter/nf_conntrack_l4proto.h>
b20ab9cc	29	#include <net/netfilter/nf_log.h>
7e5d03bb	30
58a3c9bb	31	static DEFINE_MUTEX(nf_ct_helper_mutex);
12f7a505 PNA	32	struct hlist_head *nf_ct_helper_hash __read_mostly;
	33	EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
	34	unsigned int nf_ct_helper_hsize __read_mostly;
	35	EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
b8a7fe6c	36	static unsigned int nf_ct_helper_count __read_mostly;
b8a7fe6c	37
3bb398d9	38	static bool nf_ct_auto_assign_helper __read_mostly = false;
a9006892 EL	39	module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
a9006892 EL	40	MODULE_PARM_DESC(nf_conntrack_helper,
3bb398d9	41	"Enable automatic conntrack helper assignment (default 0)");
a9006892	42
08010a21 FL	43	static DEFINE_MUTEX(nf_ct_nat_helpers_mutex);
	44	static struct list_head nf_ct_nat_helpers __read_mostly;
	45
b8a7fe6c PM	46	/* Stupid hash, but collision free for the default registrations of the
	47	* helpers currently in the kernel. */
	48	static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
	49	{
	50	return (((tuple->src.l3num << 8) \| tuple->dst.protonum) ^
a34c4589	51	(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
b8a7fe6c	52	}
7e5d03bb	53
226c0c0e	54	static struct nf_conntrack_helper *
7e5d03bb MJ	55	__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
7e5d03bb MJ	56	{
b8a7fe6c	57	struct nf_conntrack_helper *helper;
d4156e8c	58	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
b8a7fe6c	59	unsigned int h;
7e5d03bb	60
b8a7fe6c PM	61	if (!nf_ct_helper_count)
	62	return NULL;
	63
	64	h = helper_hash(tuple);
b67bfe0d	65	hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) {
b8a7fe6c PM	66	if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
b8a7fe6c PM	67	return helper;
7e5d03bb MJ	68	}
	69	return NULL;
	70	}
7e5d03bb MJ	71
7e5d03bb MJ	72	struct nf_conntrack_helper *
794e6871	73	__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
7e5d03bb MJ	74	{
7e5d03bb MJ	75	struct nf_conntrack_helper *h;
b8a7fe6c	76	unsigned int i;
7e5d03bb	77
b8a7fe6c	78	for (i = 0; i < nf_ct_helper_hsize; i++) {
b67bfe0d	79	hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) {
6114cc51 FW	80	if (strcmp(h->name, name))
	81	continue;
	82
	83	if (h->tuple.src.l3num != NFPROTO_UNSPEC &&
	84	h->tuple.src.l3num != l3num)
	85	continue;
	86
	87	if (h->tuple.dst.protonum == protonum)
b8a7fe6c PM	88	return h;
b8a7fe6c PM	89	}
7e5d03bb	90	}
7e5d03bb MJ	91	return NULL;
7e5d03bb MJ	92	}
794e6871	93	EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
7e5d03bb	94
84f3bb9a PM	95	struct nf_conntrack_helper *
	96	nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	97	{
	98	struct nf_conntrack_helper *h;
	99
8b5995d0 GF	100	rcu_read_lock();
8b5995d0 GF	101
84f3bb9a PM	102	h = __nf_conntrack_helper_find(name, l3num, protonum);
	103	#ifdef CONFIG_MODULES
	104	if (h == NULL) {
8b5995d0 GF	105	rcu_read_unlock();
	106	if (request_module("nfct-helper-%s", name) == 0) {
	107	rcu_read_lock();
84f3bb9a	108	h = __nf_conntrack_helper_find(name, l3num, protonum);
8b5995d0 GF	109	} else {
	110	return h;
	111	}
84f3bb9a PM	112	}
	113	#endif
	114	if (h != NULL && !try_module_get(h->me))
	115	h = NULL;
9338d7b4 LZ	116	if (h != NULL && !refcount_inc_not_zero(&h->refcnt)) {
	117	module_put(h->me);
	118	h = NULL;
	119	}
84f3bb9a	120
8b5995d0 GF	121	rcu_read_unlock();
8b5995d0 GF	122
84f3bb9a PM	123	return h;
	124	}
	125	EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
	126
d91fc59c LZ	127	void nf_conntrack_helper_put(struct nf_conntrack_helper *helper)
d91fc59c LZ	128	{
9338d7b4	129	refcount_dec(&helper->refcnt);
d91fc59c LZ	130	module_put(helper->me);
	131	}
	132	EXPORT_SYMBOL_GPL(nf_conntrack_helper_put);
	133
08010a21 FL	134	static struct nf_conntrack_nat_helper *
	135	nf_conntrack_nat_helper_find(const char *mod_name)
	136	{
	137	struct nf_conntrack_nat_helper *cur;
	138	bool found = false;
	139
	140	list_for_each_entry_rcu(cur, &nf_ct_nat_helpers, list) {
	141	if (!strcmp(cur->mod_name, mod_name)) {
	142	found = true;
	143	break;
	144	}
	145	}
	146	return found ? cur : NULL;
	147	}
	148
	149	int
	150	nf_nat_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	151	{
	152	struct nf_conntrack_helper *h;
	153	struct nf_conntrack_nat_helper *nat;
	154	char mod_name[NF_CT_HELPER_NAME_LEN];
	155	int ret = 0;
	156
	157	rcu_read_lock();
	158	h = __nf_conntrack_helper_find(name, l3num, protonum);
	159	if (!h) {
	160	rcu_read_unlock();
	161	return -ENOENT;
	162	}
	163
	164	nat = nf_conntrack_nat_helper_find(h->nat_mod_name);
	165	if (!nat) {
	166	snprintf(mod_name, sizeof(mod_name), "%s", h->nat_mod_name);
	167	rcu_read_unlock();
	168	request_module(mod_name);
	169
	170	rcu_read_lock();
	171	nat = nf_conntrack_nat_helper_find(mod_name);
	172	if (!nat) {
	173	rcu_read_unlock();
	174	return -ENOENT;
	175	}
	176	}
	177
	178	if (!try_module_get(nat->module))
	179	ret = -ENOENT;
	180
	181	rcu_read_unlock();
	182	return ret;
	183	}
	184	EXPORT_SYMBOL_GPL(nf_nat_helper_try_module_get);
	185
	186	void nf_nat_helper_put(struct nf_conntrack_helper *helper)
	187	{
	188	struct nf_conntrack_nat_helper *nat;
	189
	190	nat = nf_conntrack_nat_helper_find(helper->nat_mod_name);
	191	if (WARN_ON_ONCE(!nat))
	192	return;
	193
	194	module_put(nat->module);
	195	}
	196	EXPORT_SYMBOL_GPL(nf_nat_helper_put);
	197
1afc5679	198	struct nf_conn_help *
440534d3	199	nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
b560580a PM	200	{
	201	struct nf_conn_help *help;
	202
9f0f3ebe	203	help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
b560580a PM	204	if (help)
	205	INIT_HLIST_HEAD(&help->expectations);
	206	else
	207	pr_debug("failed to add helper extension area");
	208	return help;
	209	}
	210	EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
	211
dfe75ff8 JK	212	static struct nf_conntrack_helper *
	213	nf_ct_lookup_helper(struct nf_conn ct, struct net net)
	214	{
	215	if (!net->ct.sysctl_auto_assign_helper) {
	216	if (net->ct.auto_assign_helper_warned)
	217	return NULL;
	218	if (!__nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple))
	219	return NULL;
	220	pr_info("nf_conntrack: default automatic helper assignment "
	221	"has been turned off for security reasons and CT-based "
	222	" firewall rule not found. Use the iptables CT target "
	223	"to attach helpers instead.\n");
	224	net->ct.auto_assign_helper_warned = 1;
	225	return NULL;
	226	}
	227
	228	return __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
	229	}
	230
	231
b2a15a60 PM	232	int __nf_ct_try_assign_helper(struct nf_conn ct, struct nf_conn tmpl,
b2a15a60 PM	233	gfp_t flags)
226c0c0e	234	{
b2a15a60 PM	235	struct nf_conntrack_helper *helper = NULL;
b2a15a60 PM	236	struct nf_conn_help *help;
a9006892	237	struct net *net = nf_ct_net(ct);
226c0c0e	238
6714cf54 PNA	239	/* We already got a helper explicitly attached. The function
	240	* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	241	* the helper up again. Since now the user is in full control of
	242	* making consistent helper configurations, skip this automatic
	243	* re-lookup, otherwise we'll lose the helper.
	244	*/
	245	if (test_bit(IPS_HELPER_BIT, &ct->status))
	246	return 0;
	247
b2a15a60 PM	248	if (tmpl != NULL) {
b2a15a60 PM	249	help = nfct_help(tmpl);
6714cf54	250	if (help != NULL) {
b2a15a60	251	helper = help->helper;
6714cf54 PNA	252	set_bit(IPS_HELPER_BIT, &ct->status);
6714cf54 PNA	253	}
b2a15a60 PM	254	}
	255
	256	help = nfct_help(ct);
a9006892	257
226c0c0e	258	if (helper == NULL) {
dfe75ff8 JK	259	helper = nf_ct_lookup_helper(ct, net);
	260	if (helper == NULL) {
	261	if (help)
	262	RCU_INIT_POINTER(help->helper, NULL);
	263	return 0;
	264	}
226c0c0e PNA	265	}
	266
	267	if (help == NULL) {
440534d3	268	help = nf_ct_helper_ext_add(ct, flags);
cf71c03e PN	269	if (help == NULL)
cf71c03e PN	270	return -ENOMEM;
226c0c0e	271	} else {
32f53760 PNA	272	/* We only allow helper re-assignment of the same sort since
	273	* we cannot reallocate the helper extension area.
	274	*/
6e2f0aa8 FW	275	struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
	276
	277	if (tmp && tmp->help != helper->help) {
32f53760	278	RCU_INIT_POINTER(help->helper, NULL);
cf71c03e	279	return 0;
32f53760	280	}
226c0c0e PNA	281	}
226c0c0e PNA	282
cf778b00	283	rcu_assign_pointer(help->helper, helper);
cf71c03e PN	284
cf71c03e PN	285	return 0;
226c0c0e PNA	286	}
	287	EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
	288
01cfa0a4	289	/* appropriate ct lock protecting must be taken by caller */
ff1acc49	290	static int unhelp(struct nf_conn ct, void me)
7e5d03bb	291	{
7e5d03bb MJ	292	struct nf_conn_help *help = nfct_help(ct);
7e5d03bb MJ	293
ca7433df	294	if (help && rcu_dereference_raw(help->helper) == me) {
7e5d03bb	295	nf_conntrack_event(IPCT_HELPER, ct);
a9b3cd7f	296	RCU_INIT_POINTER(help->helper, NULL);
7e5d03bb	297	}
ff1acc49 LZ	298
ff1acc49 LZ	299	/* We are not intended to delete this conntrack. */
7e5d03bb MJ	300	return 0;
	301	}
	302
9858a3ae PNA	303	void nf_ct_helper_destroy(struct nf_conn *ct)
	304	{
	305	struct nf_conn_help *help = nfct_help(ct);
	306	struct nf_conntrack_helper *helper;
	307
	308	if (help) {
	309	rcu_read_lock();
	310	helper = rcu_dereference(help->helper);
	311	if (helper && helper->destroy)
	312	helper->destroy(ct);
	313	rcu_read_unlock();
	314	}
	315	}
	316
544d5c7d PNA	317	static LIST_HEAD(nf_ct_helper_expectfn_list);
	318
	319	void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
	320	{
ca7433df	321	spin_lock_bh(&nf_conntrack_expect_lock);
544d5c7d	322	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
ca7433df	323	spin_unlock_bh(&nf_conntrack_expect_lock);
544d5c7d PNA	324	}
	325	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
	326
	327	void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
	328	{
ca7433df	329	spin_lock_bh(&nf_conntrack_expect_lock);
544d5c7d	330	list_del_rcu(&n->head);
ca7433df	331	spin_unlock_bh(&nf_conntrack_expect_lock);
544d5c7d PNA	332	}
	333	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
	334
8b5995d0	335	/* Caller should hold the rcu lock */
544d5c7d PNA	336	struct nf_ct_helper_expectfn *
	337	nf_ct_helper_expectfn_find_by_name(const char *name)
	338	{
	339	struct nf_ct_helper_expectfn *cur;
	340	bool found = false;
	341
544d5c7d PNA	342	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	343	if (!strcmp(cur->name, name)) {
	344	found = true;
	345	break;
	346	}
	347	}
544d5c7d PNA	348	return found ? cur : NULL;
	349	}
	350	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
	351
8b5995d0	352	/* Caller should hold the rcu lock */
544d5c7d PNA	353	struct nf_ct_helper_expectfn *
	354	nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
	355	{
	356	struct nf_ct_helper_expectfn *cur;
	357	bool found = false;
	358
544d5c7d PNA	359	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	360	if (cur->expectfn == symbol) {
	361	found = true;
	362	break;
	363	}
	364	}
544d5c7d PNA	365	return found ? cur : NULL;
	366	}
	367	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
	368
b20ab9cc PNA	369	__printf(3, 4)
	370	void nf_ct_helper_log(struct sk_buff skb, const struct nf_conn ct,
	371	const char *fmt, ...)
	372	{
	373	const struct nf_conn_help *help;
	374	const struct nf_conntrack_helper *helper;
f9caed59 JP	375	struct va_format vaf;
	376	va_list args;
	377
	378	va_start(args, fmt);
	379
	380	vaf.fmt = fmt;
	381	vaf.va = &args;
b20ab9cc PNA	382
	383	/* Called from the helper function, this call never fails */
	384	help = nfct_help(ct);
	385
e2361cb9	386	/* rcu_read_lock()ed by nf_hook_thresh */
b20ab9cc PNA	387	helper = rcu_dereference(help->helper);
b20ab9cc PNA	388
30e0c6a6	389	nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
f9caed59 JP	390	"nf_ct_%s: dropping packet: %pV ", helper->name, &vaf);
	391
	392	va_end(args);
b20ab9cc PNA	393	}
	394	EXPORT_SYMBOL_GPL(nf_ct_helper_log);
	395
7e5d03bb MJ	396	int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
7e5d03bb MJ	397	{
893e093c	398	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
b8a7fe6c	399	unsigned int h = helper_hash(&me->tuple);
893e093c	400	struct nf_conntrack_helper *cur;
66e5a6b1	401	int ret = 0, i;
b8a7fe6c	402
6002f266 PM	403	BUG_ON(me->expect_policy == NULL);
6002f266 PM	404	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
af9d32ad	405	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
7e5d03bb	406
92f73221 GF	407	if (me->expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
	408	return -EINVAL;
	409
58a3c9bb	410	mutex_lock(&nf_ct_helper_mutex);
66e5a6b1 LZ	411	for (i = 0; i < nf_ct_helper_hsize; i++) {
	412	hlist_for_each_entry(cur, &nf_ct_helper_hash[i], hnode) {
	413	if (!strcmp(cur->name, me->name) &&
	414	(cur->tuple.src.l3num == NFPROTO_UNSPEC \|\|
	415	cur->tuple.src.l3num == me->tuple.src.l3num) &&
	416	cur->tuple.dst.protonum == me->tuple.dst.protonum) {
	417	ret = -EEXIST;
	418	goto out;
	419	}
	420	}
	421	}
	422
	423	/* avoid unpredictable behaviour for auto_assign_helper */
	424	if (!(me->flags & NF_CT_HELPER_F_USERSPACE)) {
	425	hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
	426	if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple,
	427	&mask)) {
	428	ret = -EEXIST;
	429	goto out;
	430	}
12f7a505 PNA	431	}
12f7a505 PNA	432	}
9338d7b4	433	refcount_set(&me->refcnt, 1);
58a3c9bb	434	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
b8a7fe6c	435	nf_ct_helper_count++;
12f7a505	436	out:
58a3c9bb	437	mutex_unlock(&nf_ct_helper_mutex);
12f7a505	438	return ret;
7e5d03bb	439	}
13b18339	440	EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
7e5d03bb	441
ac7b8483	442	static bool expect_iter_me(struct nf_conntrack_expect exp, void data)
7e5d03bb	443	{
ac7b8483 FW	444	struct nf_conn_help *help = nfct_help(exp->master);
	445	const struct nf_conntrack_helper *me = data;
	446	const struct nf_conntrack_helper *this;
	447
	448	if (exp->helper == me)
	449	return true;
436a850d	450
ac7b8483 FW	451	this = rcu_dereference_protected(help->helper,
	452	lockdep_is_held(&nf_conntrack_expect_lock));
	453	return this == me;
	454	}
	455
	456	void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
	457	{
436a850d FW	458	mutex_lock(&nf_ct_helper_mutex);
	459	hlist_del_rcu(&me->hnode);
	460	nf_ct_helper_count--;
	461	mutex_unlock(&nf_ct_helper_mutex);
	462
	463	/* Make sure every nothing is still using the helper unless its a
	464	* connection in the hash.
	465	*/
	466	synchronize_rcu();
7e5d03bb	467
ac7b8483	468	nf_ct_expect_iterate_destroy(expect_iter_me, NULL);
ff1acc49	469	nf_ct_iterate_destroy(unhelp, me);
ad9852af GF	470
	471	/* Maybe someone has gotten the helper already when unhelp above.
	472	* So need to wait it.
	473	*/
	474	synchronize_rcu();
68047937	475	}
13b18339	476	EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
ceceae1b	477
82de0be6 GF	478	void nf_ct_helper_init(struct nf_conntrack_helper *helper,
	479	u16 l3num, u16 protonum, const char *name,
	480	u16 default_port, u16 spec_port, u32 id,
	481	const struct nf_conntrack_expect_policy *exp_pol,
9f0f3ebe	482	u32 expect_class_max,
82de0be6 GF	483	int (help)(struct sk_buff skb, unsigned int protoff,
	484	struct nf_conn *ct,
	485	enum ip_conntrack_info ctinfo),
	486	int (from_nlattr)(struct nlattr attr,
	487	struct nf_conn *ct),
	488	struct module *module)
	489	{
	490	helper->tuple.src.l3num = l3num;
	491	helper->tuple.dst.protonum = protonum;
	492	helper->tuple.src.u.all = htons(spec_port);
	493	helper->expect_policy = exp_pol;
	494	helper->expect_class_max = expect_class_max;
82de0be6 GF	495	helper->help = help;
	496	helper->from_nlattr = from_nlattr;
	497	helper->me = module;
08010a21 FL	498	snprintf(helper->nat_mod_name, sizeof(helper->nat_mod_name),
08010a21 FL	499	NF_NAT_HELPER_PREFIX "%s", name);
82de0be6 GF	500
	501	if (spec_port == default_port)
	502	snprintf(helper->name, sizeof(helper->name), "%s", name);
	503	else
	504	snprintf(helper->name, sizeof(helper->name), "%s-%u", name, id);
	505	}
	506	EXPORT_SYMBOL_GPL(nf_ct_helper_init);
	507
	508	int nf_conntrack_helpers_register(struct nf_conntrack_helper *helper,
	509	unsigned int n)
	510	{
	511	unsigned int i;
	512	int err = 0;
	513
	514	for (i = 0; i < n; i++) {
	515	err = nf_conntrack_helper_register(&helper[i]);
	516	if (err < 0)
	517	goto err;
	518	}
	519
	520	return err;
	521	err:
	522	if (i > 0)
	523	nf_conntrack_helpers_unregister(helper, i);
	524	return err;
	525	}
	526	EXPORT_SYMBOL_GPL(nf_conntrack_helpers_register);
	527
	528	void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *helper,
	529	unsigned int n)
	530	{
	531	while (n-- > 0)
	532	nf_conntrack_helper_unregister(&helper[n]);
	533	}
	534	EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister);
	535
08010a21 FL	536	void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat)
	537	{
	538	mutex_lock(&nf_ct_nat_helpers_mutex);
	539	list_add_rcu(&nat->list, &nf_ct_nat_helpers);
	540	mutex_unlock(&nf_ct_nat_helpers_mutex);
	541	}
	542	EXPORT_SYMBOL_GPL(nf_nat_helper_register);
	543
	544	void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat)
	545	{
	546	mutex_lock(&nf_ct_nat_helpers_mutex);
	547	list_del_rcu(&nat->list);
	548	mutex_unlock(&nf_ct_nat_helpers_mutex);
	549	}
	550	EXPORT_SYMBOL_GPL(nf_nat_helper_unregister);
	551
23f671a1	552	static const struct nf_ct_ext_type helper_extend = {
ceceae1b YK	553	.len = sizeof(struct nf_conn_help),
	554	.align = __alignof__(struct nf_conn_help),
	555	.id = NF_CT_EXT_HELPER,
	556	};
	557
fc3893fd	558	void nf_conntrack_helper_pernet_init(struct net *net)
ceceae1b	559	{
a9006892 EL	560	net->ct.auto_assign_helper_warned = false;
a9006892 EL	561	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
5e615b22	562	}
a9006892	563
5e615b22 G	564	int nf_conntrack_helper_init(void)
	565	{
	566	int ret;
	567	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	568	nf_ct_helper_hash =
	569	nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	570	if (!nf_ct_helper_hash)
	571	return -ENOMEM;
	572
	573	ret = nf_ct_extend_register(&helper_extend);
	574	if (ret < 0) {
	575	pr_err("nf_ct_helper: Unable to register helper extension.\n");
	576	goto out_extend;
a9006892 EL	577	}
a9006892 EL	578
08010a21	579	INIT_LIST_HEAD(&nf_ct_nat_helpers);
b8a7fe6c	580	return 0;
5e615b22	581	out_extend:
285189c7	582	kvfree(nf_ct_helper_hash);
5e615b22	583	return ret;
ceceae1b YK	584	}
ceceae1b YK	585
5e615b22	586	void nf_conntrack_helper_fini(void)
ceceae1b	587	{
5e615b22	588	nf_ct_extend_unregister(&helper_extend);
285189c7	589	kvfree(nf_ct_helper_hash);
ceceae1b	590	}