[linux-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_conntrack_seqadj.h>
#include <net/netfilter/nf_log.h>
#include <net/ip.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 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;
}

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("%s", 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);

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;

	/* 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 (WARN_ON_ONCE(!tmpl))
		return 0;

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

	help = nfct_help(ct);

	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);

/* 'skb' should already be pulled to nh_ofs. */
int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct,
		 enum ip_conntrack_info ctinfo, u16 proto)
{
	const struct nf_conntrack_helper *helper;
	const struct nf_conn_help *help;
	unsigned int protoff;
	int err;

	if (ctinfo == IP_CT_RELATED_REPLY)
		return NF_ACCEPT;

	help = nfct_help(ct);
	if (!help)
		return NF_ACCEPT;

	helper = rcu_dereference(help->helper);
	if (!helper)
		return NF_ACCEPT;

	if (helper->tuple.src.l3num != NFPROTO_UNSPEC &&
	    helper->tuple.src.l3num != proto)
		return NF_ACCEPT;

	switch (proto) {
	case NFPROTO_IPV4:
		protoff = ip_hdrlen(skb);
		proto = ip_hdr(skb)->protocol;
		break;
	case NFPROTO_IPV6: {
		u8 nexthdr = ipv6_hdr(skb)->nexthdr;
		__be16 frag_off;
		int ofs;

		ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
				       &frag_off);
		if (ofs < 0 || (frag_off & htons(~0x7)) != 0) {
			pr_debug("proto header not found\n");
			return NF_ACCEPT;
		}
		protoff = ofs;
		proto = nexthdr;
		break;
	}
	default:
		WARN_ONCE(1, "helper invoked on non-IP family!");
		return NF_DROP;
	}

	if (helper->tuple.dst.protonum != proto)
		return NF_ACCEPT;

	err = helper->help(skb, protoff, ct, ctinfo);
	if (err != NF_ACCEPT)
		return err;

	/* Adjust seqs after helper.  This is needed due to some helpers (e.g.,
	 * FTP with NAT) adusting the TCP payload size when mangling IP
	 * addresses and/or port numbers in the text-based control connection.
	 */
	if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
	    !nf_ct_seq_adjust(skb, ct, ctinfo, protoff))
		return NF_DROP;
	return NF_ACCEPT;
}
EXPORT_SYMBOL_GPL(nf_ct_helper);

int nf_ct_add_helper(struct nf_conn *ct, const char *name, u8 family,
		     u8 proto, bool nat, struct nf_conntrack_helper **hp)
{
	struct nf_conntrack_helper *helper;
	struct nf_conn_help *help;
	int ret = 0;

	helper = nf_conntrack_helper_try_module_get(name, family, proto);
	if (!helper)
		return -EINVAL;

	help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
	if (!help) {
		nf_conntrack_helper_put(helper);
		return -ENOMEM;
	}
#if IS_ENABLED(CONFIG_NF_NAT)
	if (nat) {
		ret = nf_nat_helper_try_module_get(name, family, proto);
		if (ret) {
			nf_conntrack_helper_put(helper);
			return ret;
		}
	}
#endif
	rcu_assign_pointer(help->helper, helper);
	*hp = helper;
	return ret;
}
EXPORT_SYMBOL_GPL(nf_ct_add_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);
}
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);

int nf_conntrack_helper_init(void)
{
	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;

	INIT_LIST_HEAD(&nf_ct_nat_helpers);
	return 0;
}

void nf_conntrack_helper_fini(void)
{
	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>
ca71277f	29	#include <net/netfilter/nf_conntrack_seqadj.h>
b20ab9cc	30	#include <net/netfilter/nf_log.h>
ca71277f	31	#include <net/ip.h>
7e5d03bb	32
58a3c9bb	33	static DEFINE_MUTEX(nf_ct_helper_mutex);
12f7a505 PNA	34	struct hlist_head *nf_ct_helper_hash __read_mostly;
	35	EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
	36	unsigned int nf_ct_helper_hsize __read_mostly;
	37	EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
b8a7fe6c	38	static unsigned int nf_ct_helper_count __read_mostly;
b8a7fe6c	39
08010a21 FL	40	static DEFINE_MUTEX(nf_ct_nat_helpers_mutex);
	41	static struct list_head nf_ct_nat_helpers __read_mostly;
	42
b8a7fe6c PM	43	/* Stupid hash, but collision free for the default registrations of the
	44	* helpers currently in the kernel. */
	45	static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
	46	{
	47	return (((tuple->src.l3num << 8) \| tuple->dst.protonum) ^
a34c4589	48	(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
b8a7fe6c	49	}
7e5d03bb	50
7e5d03bb	51	struct nf_conntrack_helper *
794e6871	52	__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
7e5d03bb MJ	53	{
7e5d03bb MJ	54	struct nf_conntrack_helper *h;
b8a7fe6c	55	unsigned int i;
7e5d03bb	56
b8a7fe6c	57	for (i = 0; i < nf_ct_helper_hsize; i++) {
b67bfe0d	58	hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) {
6114cc51 FW	59	if (strcmp(h->name, name))
	60	continue;
	61
	62	if (h->tuple.src.l3num != NFPROTO_UNSPEC &&
	63	h->tuple.src.l3num != l3num)
	64	continue;
	65
	66	if (h->tuple.dst.protonum == protonum)
b8a7fe6c PM	67	return h;
b8a7fe6c PM	68	}
7e5d03bb	69	}
7e5d03bb MJ	70	return NULL;
7e5d03bb MJ	71	}
794e6871	72	EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
7e5d03bb	73
84f3bb9a PM	74	struct nf_conntrack_helper *
	75	nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	76	{
	77	struct nf_conntrack_helper *h;
	78
8b5995d0 GF	79	rcu_read_lock();
8b5995d0 GF	80
84f3bb9a PM	81	h = __nf_conntrack_helper_find(name, l3num, protonum);
	82	#ifdef CONFIG_MODULES
	83	if (h == NULL) {
8b5995d0 GF	84	rcu_read_unlock();
	85	if (request_module("nfct-helper-%s", name) == 0) {
	86	rcu_read_lock();
84f3bb9a	87	h = __nf_conntrack_helper_find(name, l3num, protonum);
8b5995d0 GF	88	} else {
	89	return h;
	90	}
84f3bb9a PM	91	}
	92	#endif
	93	if (h != NULL && !try_module_get(h->me))
	94	h = NULL;
9338d7b4 LZ	95	if (h != NULL && !refcount_inc_not_zero(&h->refcnt)) {
	96	module_put(h->me);
	97	h = NULL;
	98	}
84f3bb9a	99
8b5995d0 GF	100	rcu_read_unlock();
8b5995d0 GF	101
84f3bb9a PM	102	return h;
	103	}
	104	EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
	105
d91fc59c LZ	106	void nf_conntrack_helper_put(struct nf_conntrack_helper *helper)
d91fc59c LZ	107	{
9338d7b4	108	refcount_dec(&helper->refcnt);
d91fc59c LZ	109	module_put(helper->me);
	110	}
	111	EXPORT_SYMBOL_GPL(nf_conntrack_helper_put);
	112
08010a21 FL	113	static struct nf_conntrack_nat_helper *
	114	nf_conntrack_nat_helper_find(const char *mod_name)
	115	{
	116	struct nf_conntrack_nat_helper *cur;
	117	bool found = false;
	118
	119	list_for_each_entry_rcu(cur, &nf_ct_nat_helpers, list) {
	120	if (!strcmp(cur->mod_name, mod_name)) {
	121	found = true;
	122	break;
	123	}
	124	}
	125	return found ? cur : NULL;
	126	}
	127
	128	int
	129	nf_nat_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
	130	{
	131	struct nf_conntrack_helper *h;
	132	struct nf_conntrack_nat_helper *nat;
	133	char mod_name[NF_CT_HELPER_NAME_LEN];
	134	int ret = 0;
	135
	136	rcu_read_lock();
	137	h = __nf_conntrack_helper_find(name, l3num, protonum);
	138	if (!h) {
	139	rcu_read_unlock();
	140	return -ENOENT;
	141	}
	142
	143	nat = nf_conntrack_nat_helper_find(h->nat_mod_name);
	144	if (!nat) {
	145	snprintf(mod_name, sizeof(mod_name), "%s", h->nat_mod_name);
	146	rcu_read_unlock();
b8acd431	147	request_module("%s", mod_name);
08010a21 FL	148
	149	rcu_read_lock();
	150	nat = nf_conntrack_nat_helper_find(mod_name);
	151	if (!nat) {
	152	rcu_read_unlock();
	153	return -ENOENT;
	154	}
	155	}
	156
	157	if (!try_module_get(nat->module))
	158	ret = -ENOENT;
	159
	160	rcu_read_unlock();
	161	return ret;
	162	}
	163	EXPORT_SYMBOL_GPL(nf_nat_helper_try_module_get);
	164
	165	void nf_nat_helper_put(struct nf_conntrack_helper *helper)
	166	{
	167	struct nf_conntrack_nat_helper *nat;
	168
	169	nat = nf_conntrack_nat_helper_find(helper->nat_mod_name);
	170	if (WARN_ON_ONCE(!nat))
	171	return;
	172
	173	module_put(nat->module);
	174	}
	175	EXPORT_SYMBOL_GPL(nf_nat_helper_put);
	176
1afc5679	177	struct nf_conn_help *
440534d3	178	nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
b560580a PM	179	{
	180	struct nf_conn_help *help;
	181
9f0f3ebe	182	help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
b560580a PM	183	if (help)
	184	INIT_HLIST_HEAD(&help->expectations);
	185	else
	186	pr_debug("failed to add helper extension area");
	187	return help;
	188	}
	189	EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
	190
b2a15a60 PM	191	int __nf_ct_try_assign_helper(struct nf_conn ct, struct nf_conn tmpl,
b2a15a60 PM	192	gfp_t flags)
226c0c0e	193	{
b2a15a60 PM	194	struct nf_conntrack_helper *helper = NULL;
b2a15a60 PM	195	struct nf_conn_help *help;
226c0c0e	196
6714cf54 PNA	197	/* We already got a helper explicitly attached. The function
	198	* nf_conntrack_alter_reply - in case NAT is in use - asks for looking
	199	* the helper up again. Since now the user is in full control of
	200	* making consistent helper configurations, skip this automatic
	201	* re-lookup, otherwise we'll lose the helper.
	202	*/
	203	if (test_bit(IPS_HELPER_BIT, &ct->status))
	204	return 0;
	205
b1185090 PNA	206	if (WARN_ON_ONCE(!tmpl))
	207	return 0;
	208
	209	help = nfct_help(tmpl);
	210	if (help != NULL) {
	211	helper = rcu_dereference(help->helper);
	212	set_bit(IPS_HELPER_BIT, &ct->status);
b2a15a60 PM	213	}
	214
	215	help = nfct_help(ct);
a9006892	216
226c0c0e	217	if (helper == NULL) {
b1185090 PNA	218	if (help)
	219	RCU_INIT_POINTER(help->helper, NULL);
	220	return 0;
226c0c0e PNA	221	}
	222
	223	if (help == NULL) {
440534d3	224	help = nf_ct_helper_ext_add(ct, flags);
cf71c03e PN	225	if (help == NULL)
cf71c03e PN	226	return -ENOMEM;
226c0c0e	227	} else {
32f53760 PNA	228	/* We only allow helper re-assignment of the same sort since
	229	* we cannot reallocate the helper extension area.
	230	*/
6e2f0aa8 FW	231	struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
	232
	233	if (tmp && tmp->help != helper->help) {
32f53760	234	RCU_INIT_POINTER(help->helper, NULL);
cf71c03e	235	return 0;
32f53760	236	}
226c0c0e PNA	237	}
226c0c0e PNA	238
cf778b00	239	rcu_assign_pointer(help->helper, helper);
cf71c03e PN	240
cf71c03e PN	241	return 0;
226c0c0e PNA	242	}
	243	EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
	244
ca71277f XL	245	/* 'skb' should already be pulled to nh_ofs. */
	246	int nf_ct_helper(struct sk_buff skb, struct nf_conn ct,
	247	enum ip_conntrack_info ctinfo, u16 proto)
	248	{
	249	const struct nf_conntrack_helper *helper;
	250	const struct nf_conn_help *help;
	251	unsigned int protoff;
	252	int err;
	253
	254	if (ctinfo == IP_CT_RELATED_REPLY)
	255	return NF_ACCEPT;
	256
	257	help = nfct_help(ct);
	258	if (!help)
	259	return NF_ACCEPT;
	260
	261	helper = rcu_dereference(help->helper);
	262	if (!helper)
	263	return NF_ACCEPT;
	264
	265	if (helper->tuple.src.l3num != NFPROTO_UNSPEC &&
	266	helper->tuple.src.l3num != proto)
	267	return NF_ACCEPT;
	268
	269	switch (proto) {
	270	case NFPROTO_IPV4:
	271	protoff = ip_hdrlen(skb);
	272	proto = ip_hdr(skb)->protocol;
	273	break;
	274	case NFPROTO_IPV6: {
	275	u8 nexthdr = ipv6_hdr(skb)->nexthdr;
	276	__be16 frag_off;
	277	int ofs;
	278
	279	ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
	280	&frag_off);
	281	if (ofs < 0 \|\| (frag_off & htons(~0x7)) != 0) {
	282	pr_debug("proto header not found\n");
	283	return NF_ACCEPT;
	284	}
	285	protoff = ofs;
	286	proto = nexthdr;
	287	break;
	288	}
	289	default:
	290	WARN_ONCE(1, "helper invoked on non-IP family!");
	291	return NF_DROP;
	292	}
	293
	294	if (helper->tuple.dst.protonum != proto)
	295	return NF_ACCEPT;
	296
	297	err = helper->help(skb, protoff, ct, ctinfo);
	298	if (err != NF_ACCEPT)
	299	return err;
	300
	301	/* Adjust seqs after helper. This is needed due to some helpers (e.g.,
	302	* FTP with NAT) adusting the TCP payload size when mangling IP
	303	* addresses and/or port numbers in the text-based control connection.
	304	*/
	305	if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
	306	!nf_ct_seq_adjust(skb, ct, ctinfo, protoff))
	307	return NF_DROP;
	308	return NF_ACCEPT;
309	}
310	EXPORT_SYMBOL_GPL(nf_ct_helper);
311
f96cba2e XL	312	int nf_ct_add_helper(struct nf_conn ct, const char name, u8 family,
	313	u8 proto, bool nat, struct nf_conntrack_helper **hp)
	314	{
	315	struct nf_conntrack_helper *helper;
	316	struct nf_conn_help *help;
	317	int ret = 0;
	318
	319	helper = nf_conntrack_helper_try_module_get(name, family, proto);
	320	if (!helper)
	321	return -EINVAL;
	322
	323	help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
	324	if (!help) {
	325	nf_conntrack_helper_put(helper);
	326	return -ENOMEM;
	327	}
	328	#if IS_ENABLED(CONFIG_NF_NAT)
	329	if (nat) {
	330	ret = nf_nat_helper_try_module_get(name, family, proto);
	331	if (ret) {
	332	nf_conntrack_helper_put(helper);
	333	return ret;
	334	}
	335	}
	336	#endif
	337	rcu_assign_pointer(help->helper, helper);
	338	*hp = helper;
	339	return ret;
	340	}
	341	EXPORT_SYMBOL_GPL(nf_ct_add_helper);
	342
01cfa0a4	343	/* appropriate ct lock protecting must be taken by caller */
ff1acc49	344	static int unhelp(struct nf_conn ct, void me)
7e5d03bb	345	{
7e5d03bb MJ	346	struct nf_conn_help *help = nfct_help(ct);
7e5d03bb MJ	347
ca7433df	348	if (help && rcu_dereference_raw(help->helper) == me) {
7e5d03bb	349	nf_conntrack_event(IPCT_HELPER, ct);
a9b3cd7f	350	RCU_INIT_POINTER(help->helper, NULL);
7e5d03bb	351	}
ff1acc49 LZ	352
ff1acc49 LZ	353	/* We are not intended to delete this conntrack. */
7e5d03bb MJ	354	return 0;
	355	}
	356
9858a3ae PNA	357	void nf_ct_helper_destroy(struct nf_conn *ct)
	358	{
	359	struct nf_conn_help *help = nfct_help(ct);
	360	struct nf_conntrack_helper *helper;
	361
	362	if (help) {
	363	rcu_read_lock();
	364	helper = rcu_dereference(help->helper);
	365	if (helper && helper->destroy)
	366	helper->destroy(ct);
	367	rcu_read_unlock();
	368	}
	369	}
	370
544d5c7d PNA	371	static LIST_HEAD(nf_ct_helper_expectfn_list);
	372
	373	void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
	374	{
ca7433df	375	spin_lock_bh(&nf_conntrack_expect_lock);
544d5c7d	376	list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
ca7433df	377	spin_unlock_bh(&nf_conntrack_expect_lock);
544d5c7d PNA	378	}
	379	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
	380
	381	void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
	382	{
ca7433df	383	spin_lock_bh(&nf_conntrack_expect_lock);
544d5c7d	384	list_del_rcu(&n->head);
ca7433df	385	spin_unlock_bh(&nf_conntrack_expect_lock);
544d5c7d PNA	386	}
	387	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
	388
8b5995d0	389	/* Caller should hold the rcu lock */
544d5c7d PNA	390	struct nf_ct_helper_expectfn *
	391	nf_ct_helper_expectfn_find_by_name(const char *name)
	392	{
	393	struct nf_ct_helper_expectfn *cur;
	394	bool found = false;
	395
544d5c7d PNA	396	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	397	if (!strcmp(cur->name, name)) {
	398	found = true;
	399	break;
	400	}
	401	}
544d5c7d PNA	402	return found ? cur : NULL;
	403	}
	404	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
	405
8b5995d0	406	/* Caller should hold the rcu lock */
544d5c7d PNA	407	struct nf_ct_helper_expectfn *
	408	nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
	409	{
	410	struct nf_ct_helper_expectfn *cur;
	411	bool found = false;
	412
544d5c7d PNA	413	list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
	414	if (cur->expectfn == symbol) {
	415	found = true;
	416	break;
	417	}
	418	}
544d5c7d PNA	419	return found ? cur : NULL;
	420	}
	421	EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
	422
b20ab9cc PNA	423	__printf(3, 4)
	424	void nf_ct_helper_log(struct sk_buff skb, const struct nf_conn ct,
	425	const char *fmt, ...)
	426	{
	427	const struct nf_conn_help *help;
	428	const struct nf_conntrack_helper *helper;
f9caed59 JP	429	struct va_format vaf;
	430	va_list args;
	431
	432	va_start(args, fmt);
	433
	434	vaf.fmt = fmt;
	435	vaf.va = &args;
b20ab9cc PNA	436
	437	/* Called from the helper function, this call never fails */
	438	help = nfct_help(ct);
	439
e2361cb9	440	/* rcu_read_lock()ed by nf_hook_thresh */
b20ab9cc PNA	441	helper = rcu_dereference(help->helper);
b20ab9cc PNA	442
30e0c6a6	443	nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
f9caed59 JP	444	"nf_ct_%s: dropping packet: %pV ", helper->name, &vaf);
	445
	446	va_end(args);
b20ab9cc PNA	447	}
	448	EXPORT_SYMBOL_GPL(nf_ct_helper_log);
	449
7e5d03bb MJ	450	int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
7e5d03bb MJ	451	{
893e093c	452	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
b8a7fe6c	453	unsigned int h = helper_hash(&me->tuple);
893e093c	454	struct nf_conntrack_helper *cur;
66e5a6b1	455	int ret = 0, i;
b8a7fe6c	456
6002f266 PM	457	BUG_ON(me->expect_policy == NULL);
6002f266 PM	458	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
af9d32ad	459	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
7e5d03bb	460
92f73221 GF	461	if (me->expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
	462	return -EINVAL;
	463
58a3c9bb	464	mutex_lock(&nf_ct_helper_mutex);
66e5a6b1 LZ	465	for (i = 0; i < nf_ct_helper_hsize; i++) {
	466	hlist_for_each_entry(cur, &nf_ct_helper_hash[i], hnode) {
	467	if (!strcmp(cur->name, me->name) &&
	468	(cur->tuple.src.l3num == NFPROTO_UNSPEC \|\|
	469	cur->tuple.src.l3num == me->tuple.src.l3num) &&
	470	cur->tuple.dst.protonum == me->tuple.dst.protonum) {
	471	ret = -EEXIST;
	472	goto out;
	473	}
	474	}
	475	}
	476
	477	/* avoid unpredictable behaviour for auto_assign_helper */
	478	if (!(me->flags & NF_CT_HELPER_F_USERSPACE)) {
	479	hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
	480	if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple,
	481	&mask)) {
	482	ret = -EEXIST;
	483	goto out;
	484	}
12f7a505 PNA	485	}
12f7a505 PNA	486	}
9338d7b4	487	refcount_set(&me->refcnt, 1);
58a3c9bb	488	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
b8a7fe6c	489	nf_ct_helper_count++;
12f7a505	490	out:
58a3c9bb	491	mutex_unlock(&nf_ct_helper_mutex);
12f7a505	492	return ret;
7e5d03bb	493	}
13b18339	494	EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
7e5d03bb	495
ac7b8483	496	static bool expect_iter_me(struct nf_conntrack_expect exp, void data)
7e5d03bb	497	{
ac7b8483 FW	498	struct nf_conn_help *help = nfct_help(exp->master);
	499	const struct nf_conntrack_helper *me = data;
	500	const struct nf_conntrack_helper *this;
	501
	502	if (exp->helper == me)
	503	return true;
436a850d	504
ac7b8483 FW	505	this = rcu_dereference_protected(help->helper,
	506	lockdep_is_held(&nf_conntrack_expect_lock));
	507	return this == me;
	508	}
	509
	510	void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
	511	{
436a850d FW	512	mutex_lock(&nf_ct_helper_mutex);
	513	hlist_del_rcu(&me->hnode);
	514	nf_ct_helper_count--;
	515	mutex_unlock(&nf_ct_helper_mutex);
	516
	517	/* Make sure every nothing is still using the helper unless its a
	518	* connection in the hash.
	519	*/
	520	synchronize_rcu();
7e5d03bb	521
ac7b8483	522	nf_ct_expect_iterate_destroy(expect_iter_me, NULL);
ff1acc49	523	nf_ct_iterate_destroy(unhelp, me);
68047937	524	}
13b18339	525	EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
ceceae1b	526
82de0be6 GF	527	void nf_ct_helper_init(struct nf_conntrack_helper *helper,
	528	u16 l3num, u16 protonum, const char *name,
	529	u16 default_port, u16 spec_port, u32 id,
	530	const struct nf_conntrack_expect_policy *exp_pol,
9f0f3ebe	531	u32 expect_class_max,
82de0be6 GF	532	int (help)(struct sk_buff skb, unsigned int protoff,
	533	struct nf_conn *ct,
	534	enum ip_conntrack_info ctinfo),
	535	int (from_nlattr)(struct nlattr attr,
	536	struct nf_conn *ct),
	537	struct module *module)
	538	{
	539	helper->tuple.src.l3num = l3num;
	540	helper->tuple.dst.protonum = protonum;
	541	helper->tuple.src.u.all = htons(spec_port);
	542	helper->expect_policy = exp_pol;
	543	helper->expect_class_max = expect_class_max;
82de0be6 GF	544	helper->help = help;
	545	helper->from_nlattr = from_nlattr;
	546	helper->me = module;
08010a21 FL	547	snprintf(helper->nat_mod_name, sizeof(helper->nat_mod_name),
08010a21 FL	548	NF_NAT_HELPER_PREFIX "%s", name);
82de0be6 GF	549
	550	if (spec_port == default_port)
	551	snprintf(helper->name, sizeof(helper->name), "%s", name);
	552	else
	553	snprintf(helper->name, sizeof(helper->name), "%s-%u", name, id);
	554	}
	555	EXPORT_SYMBOL_GPL(nf_ct_helper_init);
	556
	557	int nf_conntrack_helpers_register(struct nf_conntrack_helper *helper,
	558	unsigned int n)
	559	{
	560	unsigned int i;
	561	int err = 0;
	562
	563	for (i = 0; i < n; i++) {
	564	err = nf_conntrack_helper_register(&helper[i]);
	565	if (err < 0)
	566	goto err;
	567	}
	568
	569	return err;
	570	err:
	571	if (i > 0)
	572	nf_conntrack_helpers_unregister(helper, i);
	573	return err;
	574	}
	575	EXPORT_SYMBOL_GPL(nf_conntrack_helpers_register);
	576
	577	void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *helper,
	578	unsigned int n)
	579	{
	580	while (n-- > 0)
	581	nf_conntrack_helper_unregister(&helper[n]);
	582	}
	583	EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister);
	584
08010a21 FL	585	void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat)
	586	{
	587	mutex_lock(&nf_ct_nat_helpers_mutex);
	588	list_add_rcu(&nat->list, &nf_ct_nat_helpers);
	589	mutex_unlock(&nf_ct_nat_helpers_mutex);
	590	}
	591	EXPORT_SYMBOL_GPL(nf_nat_helper_register);
	592
	593	void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat)
	594	{
	595	mutex_lock(&nf_ct_nat_helpers_mutex);
	596	list_del_rcu(&nat->list);
	597	mutex_unlock(&nf_ct_nat_helpers_mutex);
	598	}
	599	EXPORT_SYMBOL_GPL(nf_nat_helper_unregister);
	600
5e615b22 G	601	int nf_conntrack_helper_init(void)
5e615b22 G	602	{
5e615b22 G	603	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
	604	nf_ct_helper_hash =
	605	nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
	606	if (!nf_ct_helper_hash)
	607	return -ENOMEM;
	608
08010a21	609	INIT_LIST_HEAD(&nf_ct_nat_helpers);
b8a7fe6c	610	return 0;
ceceae1b YK	611	}
ceceae1b YK	612
5e615b22	613	void nf_conntrack_helper_fini(void)
ceceae1b	614	{
285189c7	615	kvfree(nf_ct_helper_hash);
ceceae1b	616	}