Commit 31d44a37 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge tag 'nf-next-26-01-22' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next 

Florian Westphal says:

====================
netfilter: updates for net-next

There is an issue with interval matching in nftables rbtree set type:
When userspace sends us set updates, there is a brief window where
false negative lookups may occur from the data plane.  Quoting Pablos
original cover letter:

This series addresses this issue by translating the rbtree, which keeps
the intervals in order, to binary search. The array is published to
packet path through RCU. The idea is to keep using the rbtree
datastructure for control plane, which needs to deal with updates, then
generate an array using this rbtree for binary search lookups.

Patch #1 allows to call .remove in case .abort is defined, which is
needed by this new approach. Only pipapo needs to skip .remove to speed.

Patch #2 add the binary search array approach for interval matching.

Patch #3 updates .get to use the binary search array to find for
(closest or exact) interval matching.

Patch #4 removes seqcount_rwlock_t as it is not needed anymore (new in
this series).

* tag 'nf-next-26-01-22' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next:
  netfilter: nft_set_rbtree: remove seqcount_rwlock_t
  netfilter: nft_set_rbtree: use binary search array in get command
  netfilter: nft_set_rbtree: translate rbtree to array for binary search
  netfilter: nf_tables: add .abort_skip_removal flag for set types
====================

Link: https://patch.msgid.link/20260122162935.8581-1-fw@strlen.de


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents b00a7b3a 5599fa81

include/net/netfilter/nf_tables.h

+2 −0
Original line number Diff line number Diff line
@@ -451,6 +451,7 @@ struct nft_set_ext; 
 *	@init: initialize private data of new set instance

 *	@destroy: destroy private data of set instance

 *	@gc_init: initialize garbage collection

 *	@abort_skip_removal: skip removal of elements from abort path

 *	@elemsize: element private size

 *

 *	Operations lookup, update and delete have simpler interfaces, are faster
@@ -508,6 +509,7 @@ struct nft_set_ops { 
						   const struct nft_set *set);

	void				(*gc_init)(const struct nft_set *set);



	bool				abort_skip_removal;

	unsigned int			elemsize;

};

net/netfilter/nf_tables_api.c

+2 −1
Original line number Diff line number Diff line
@@ -7807,7 +7807,8 @@ static bool nft_trans_elems_new_abort(const struct nft_ctx *ctx, 
			continue;

		}



		if (!te->set->ops->abort || nft_setelem_is_catchall(te->set, te->elems[i].priv))

		if (!te->set->ops->abort_skip_removal ||

		    nft_setelem_is_catchall(te->set, te->elems[i].priv))

			nft_setelem_remove(ctx->net, te->set, te->elems[i].priv);



		if (!nft_setelem_is_catchall(te->set, te->elems[i].priv))

net/netfilter/nft_set_pipapo.c

+2 −0
Original line number Diff line number Diff line
@@ -2370,6 +2370,7 @@ const struct nft_set_type nft_set_pipapo_type = { 
		.gc_init	= nft_pipapo_gc_init,

		.commit		= nft_pipapo_commit,

		.abort		= nft_pipapo_abort,

		.abort_skip_removal = true,

		.elemsize	= offsetof(struct nft_pipapo_elem, ext),

	},

};
@@ -2394,6 +2395,7 @@ const struct nft_set_type nft_set_pipapo_avx2_type = { 
		.gc_init	= nft_pipapo_gc_init,

		.commit		= nft_pipapo_commit,

		.abort		= nft_pipapo_abort,

		.abort_skip_removal = true,

		.elemsize	= offsetof(struct nft_pipapo_elem, ext),

	},

};

net/netfilter/nft_set_rbtree.c

+285 −144
Original line number Diff line number Diff line
@@ -10,15 +10,29 @@ 
#include <linux/module.h>

#include <linux/list.h>

#include <linux/rbtree.h>

#include <linux/bsearch.h>

#include <linux/netlink.h>

#include <linux/netfilter.h>

#include <linux/netfilter/nf_tables.h>

#include <net/netfilter/nf_tables_core.h>



struct nft_array_interval {

	struct nft_set_ext	*from;

	struct nft_set_ext	*to;

};



struct nft_array {

	u32			max_intervals;

	u32			num_intervals;

	struct nft_array_interval *intervals;

	struct rcu_head		rcu_head;

};



struct nft_rbtree {

	struct rb_root		root;

	rwlock_t		lock;

	seqcount_rwlock_t	count;

	struct nft_array __rcu	*array;

	struct nft_array	*array_next;

	unsigned long		last_gc;

};
@@ -47,67 +61,33 @@ static int nft_rbtree_cmp(const struct nft_set *set, 
		      set->klen);

}



static bool nft_rbtree_elem_expired(const struct nft_rbtree_elem *rbe)

{

	return nft_set_elem_expired(&rbe->ext);

}

struct nft_array_lookup_ctx {

	const u32	*key;

	u32		klen;

};



static const struct nft_set_ext *

__nft_rbtree_lookup(const struct net *net, const struct nft_set *set,

		    const u32 *key, unsigned int seq)

static int nft_array_lookup_cmp(const void *pkey, const void *entry)

{

	struct nft_rbtree *priv = nft_set_priv(set);

	const struct nft_rbtree_elem *rbe, *interval = NULL;

	u8 genmask = nft_genmask_cur(net);

	const struct rb_node *parent;

	int d;



	parent = rcu_dereference_raw(priv->root.rb_node);

	while (parent != NULL) {

		if (read_seqcount_retry(&priv->count, seq))

			return NULL;



		rbe = rb_entry(parent, struct nft_rbtree_elem, node);



		d = memcmp(nft_set_ext_key(&rbe->ext), key, set->klen);

		if (d < 0) {

			parent = rcu_dereference_raw(parent->rb_left);

			if (interval &&

			    !nft_rbtree_cmp(set, rbe, interval) &&

			    nft_rbtree_interval_end(rbe) &&

			    nft_rbtree_interval_start(interval))

				continue;

			if (nft_set_elem_active(&rbe->ext, genmask) &&

			    !nft_rbtree_elem_expired(rbe))

				interval = rbe;

		} else if (d > 0)

			parent = rcu_dereference_raw(parent->rb_right);

		else {

			if (!nft_set_elem_active(&rbe->ext, genmask)) {

				parent = rcu_dereference_raw(parent->rb_left);

				continue;

			}

	const struct nft_array_interval *interval = entry;

	const struct nft_array_lookup_ctx *ctx = pkey;

	int a, b;



			if (nft_rbtree_elem_expired(rbe))

				return NULL;

	if (!interval->from)

		return 1;



			if (nft_rbtree_interval_end(rbe)) {

				if (nft_set_is_anonymous(set))

					return NULL;

				parent = rcu_dereference_raw(parent->rb_left);

				interval = NULL;

				continue;

			}

	a = memcmp(ctx->key, nft_set_ext_key(interval->from), ctx->klen);

	if (!interval->to)

		b = -1;

	else

		b = memcmp(ctx->key, nft_set_ext_key(interval->to), ctx->klen);



			return &rbe->ext;

		}

	}

	if (a >= 0 && b < 0)

		return 0;



	if (set->flags & NFT_SET_INTERVAL && interval != NULL &&

	    nft_rbtree_interval_start(interval))

		return &interval->ext;

	if (a < 0)

		return -1;



	return NULL;

	return 1;

}



INDIRECT_CALLABLE_SCOPE
@@ -116,83 +96,57 @@ nft_rbtree_lookup(const struct net *net, const struct nft_set *set, 
		  const u32 *key)

{

	struct nft_rbtree *priv = nft_set_priv(set);

	unsigned int seq = read_seqcount_begin(&priv->count);

	const struct nft_set_ext *ext;

	struct nft_array *array = rcu_dereference(priv->array);

	const struct nft_array_interval *interval;

	struct nft_array_lookup_ctx ctx = {

		.key	= key,

		.klen	= set->klen,

	};



	ext = __nft_rbtree_lookup(net, set, key, seq);

	if (ext || !read_seqcount_retry(&priv->count, seq))

		return ext;

	if (!array)

		return NULL;



	read_lock_bh(&priv->lock);

	seq = read_seqcount_begin(&priv->count);

	ext = __nft_rbtree_lookup(net, set, key, seq);

	read_unlock_bh(&priv->lock);

	interval = bsearch(&ctx, array->intervals, array->num_intervals,

			   sizeof(struct nft_array_interval),

			   nft_array_lookup_cmp);

	if (!interval || nft_set_elem_expired(interval->from))

		return NULL;



	return ext;

	return interval->from;

}



static bool __nft_rbtree_get(const struct net *net, const struct nft_set *set,

			     const u32 *key, struct nft_rbtree_elem **elem,

			     unsigned int seq, unsigned int flags, u8 genmask)

{

	struct nft_rbtree_elem *rbe, *interval = NULL;

	struct nft_rbtree *priv = nft_set_priv(set);

	const struct rb_node *parent;

	const void *this;

	int d;



	parent = rcu_dereference_raw(priv->root.rb_node);

	while (parent != NULL) {

		if (read_seqcount_retry(&priv->count, seq))

			return false;



		rbe = rb_entry(parent, struct nft_rbtree_elem, node);



		this = nft_set_ext_key(&rbe->ext);

		d = memcmp(this, key, set->klen);

		if (d < 0) {

			parent = rcu_dereference_raw(parent->rb_left);

			if (!(flags & NFT_SET_ELEM_INTERVAL_END))

				interval = rbe;

		} else if (d > 0) {

			parent = rcu_dereference_raw(parent->rb_right);

			if (flags & NFT_SET_ELEM_INTERVAL_END)

				interval = rbe;

		} else {

			if (!nft_set_elem_active(&rbe->ext, genmask)) {

				parent = rcu_dereference_raw(parent->rb_left);

				continue;

			}

struct nft_array_get_ctx {

	const u32	*key;

	unsigned int	flags;

	u32		klen;

};



			if (nft_set_elem_expired(&rbe->ext))

				return false;

static int nft_array_get_cmp(const void *pkey, const void *entry)

{

	const struct nft_array_interval *interval = entry;

	const struct nft_array_get_ctx *ctx = pkey;

	int a, b;



			if (!nft_set_ext_exists(&rbe->ext, NFT_SET_EXT_FLAGS) ||

			    (*nft_set_ext_flags(&rbe->ext) & NFT_SET_ELEM_INTERVAL_END) ==

			    (flags & NFT_SET_ELEM_INTERVAL_END)) {

				*elem = rbe;

				return true;

			}

	if (!interval->from)

		return 1;



			if (nft_rbtree_interval_end(rbe))

				interval = NULL;

	a = memcmp(ctx->key, nft_set_ext_key(interval->from), ctx->klen);

	if (!interval->to)

		b = -1;

	else

		b = memcmp(ctx->key, nft_set_ext_key(interval->to), ctx->klen);



			parent = rcu_dereference_raw(parent->rb_left);

		}

	if (a >= 0) {

		if (ctx->flags & NFT_SET_ELEM_INTERVAL_END && b <= 0)

			return 0;

		else if (b < 0)

			return 0;

	}



	if (set->flags & NFT_SET_INTERVAL && interval != NULL &&

	    nft_set_elem_active(&interval->ext, genmask) &&

	    !nft_set_elem_expired(&interval->ext) &&

	    ((!nft_rbtree_interval_end(interval) &&

	      !(flags & NFT_SET_ELEM_INTERVAL_END)) ||

	     (nft_rbtree_interval_end(interval) &&

	      (flags & NFT_SET_ELEM_INTERVAL_END)))) {

		*elem = interval;

		return true;

	}

	if (a < 0)

		return -1;



	return false;

	return 1;

}



static struct nft_elem_priv *
@@ -200,24 +154,28 @@ nft_rbtree_get(const struct net *net, const struct nft_set *set, 
	       const struct nft_set_elem *elem, unsigned int flags)

{

	struct nft_rbtree *priv = nft_set_priv(set);

	unsigned int seq = read_seqcount_begin(&priv->count);

	struct nft_rbtree_elem *rbe = ERR_PTR(-ENOENT);

	const u32 *key = (const u32 *)&elem->key.val;

	u8 genmask = nft_genmask_cur(net);

	bool ret;



	ret = __nft_rbtree_get(net, set, key, &rbe, seq, flags, genmask);

	if (ret || !read_seqcount_retry(&priv->count, seq))

		return &rbe->priv;

	struct nft_array *array = rcu_dereference(priv->array);

	const struct nft_array_interval *interval;

	struct nft_array_get_ctx ctx = {

		.key	= (const u32 *)&elem->key.val,

		.flags	= flags,

		.klen	= set->klen,

	};

	struct nft_rbtree_elem *rbe;



	read_lock_bh(&priv->lock);

	seq = read_seqcount_begin(&priv->count);

	ret = __nft_rbtree_get(net, set, key, &rbe, seq, flags, genmask);

	read_unlock_bh(&priv->lock);

	if (!array)

		return ERR_PTR(-ENOENT);



	if (!ret)

	interval = bsearch(&ctx, array->intervals, array->num_intervals,

			   sizeof(struct nft_array_interval), nft_array_get_cmp);

	if (!interval || nft_set_elem_expired(interval->from))

		return ERR_PTR(-ENOENT);



	if (flags & NFT_SET_ELEM_INTERVAL_END)

		rbe = container_of(interval->to, struct nft_rbtree_elem, ext);

	else

		rbe = container_of(interval->from, struct nft_rbtree_elem, ext);



	return &rbe->priv;

}
@@ -481,6 +439,87 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set, 
	return 0;

}



static int nft_array_intervals_alloc(struct nft_array *array, u32 max_intervals)

{

	struct nft_array_interval *intervals;



	intervals = kvcalloc(max_intervals, sizeof(struct nft_array_interval),

			     GFP_KERNEL_ACCOUNT);

	if (!intervals)

		return -ENOMEM;



	if (array->intervals)

		kvfree(array->intervals);



	array->intervals = intervals;

	array->max_intervals = max_intervals;



	return 0;

}



static struct nft_array *nft_array_alloc(u32 max_intervals)

{

	struct nft_array *array;



	array = kzalloc(sizeof(*array), GFP_KERNEL_ACCOUNT);

	if (!array)

		return NULL;



	if (nft_array_intervals_alloc(array, max_intervals) < 0) {

		kfree(array);

		return NULL;

	}



	return array;

}



#define NFT_ARRAY_EXTRA_SIZE	10240



/* Similar to nft_rbtree_{u,k}size to hide details to userspace, but consider

 * packed representation coming from userspace for anonymous sets too.

 */

static u32 nft_array_elems(const struct nft_set *set)

{

	u32 nelems = atomic_read(&set->nelems);



	/* Adjacent intervals are represented with a single start element in

	 * anonymous sets, use the current element counter as is.

	 */

	if (nft_set_is_anonymous(set))

		return nelems;



	/* Add extra room for never matching interval at the beginning and open

	 * interval at the end which only use a single element to represent it.

	 * The conversion to array will compact intervals, this allows reduce

	 * memory consumption.

	 */

	return (nelems / 2) + 2;

}



static int nft_array_may_resize(const struct nft_set *set)

{

	u32 nelems = nft_array_elems(set), new_max_intervals;

	struct nft_rbtree *priv = nft_set_priv(set);

	struct nft_array *array;



	if (!priv->array_next) {

		array = nft_array_alloc(nelems + NFT_ARRAY_EXTRA_SIZE);

		if (!array)

			return -ENOMEM;



		priv->array_next = array;

	}



	if (nelems < priv->array_next->max_intervals)

		return 0;



	new_max_intervals = priv->array_next->max_intervals + NFT_ARRAY_EXTRA_SIZE;

	if (nft_array_intervals_alloc(priv->array_next, new_max_intervals) < 0)

		return -ENOMEM;



	return 0;

}



static int nft_rbtree_insert(const struct net *net, const struct nft_set *set,

			     const struct nft_set_elem *elem,

			     struct nft_elem_priv **elem_priv)
@@ -489,6 +528,9 @@ static int nft_rbtree_insert(const struct net *net, const struct nft_set *set, 
	struct nft_rbtree *priv = nft_set_priv(set);

	int err;



	if (nft_array_may_resize(set) < 0)

		return -ENOMEM;



	do {

		if (fatal_signal_pending(current))

			return -EINTR;
@@ -496,9 +538,7 @@ static int nft_rbtree_insert(const struct net *net, const struct nft_set *set, 
		cond_resched();



		write_lock_bh(&priv->lock);

		write_seqcount_begin(&priv->count);

		err = __nft_rbtree_insert(net, set, rbe, elem_priv);

		write_seqcount_end(&priv->count);

		write_unlock_bh(&priv->lock);

	} while (err == -EAGAIN);
@@ -508,9 +548,7 @@ static int nft_rbtree_insert(const struct net *net, const struct nft_set *set, 
static void nft_rbtree_erase(struct nft_rbtree *priv, struct nft_rbtree_elem *rbe)

{

	write_lock_bh(&priv->lock);

	write_seqcount_begin(&priv->count);

	rb_erase(&rbe->node, &priv->root);

	write_seqcount_end(&priv->count);

	write_unlock_bh(&priv->lock);

}
@@ -553,6 +591,9 @@ nft_rbtree_deactivate(const struct net *net, const struct nft_set *set, 
	u64 tstamp = nft_net_tstamp(net);

	int d;



	if (nft_array_may_resize(set) < 0)

		return NULL;



	while (parent != NULL) {

		rbe = rb_entry(parent, struct nft_rbtree_elem, node);
@@ -615,6 +656,11 @@ static void nft_rbtree_walk(const struct nft_ctx *ctx, 
	switch (iter->type) {

	case NFT_ITER_UPDATE:

		lockdep_assert_held(&nft_pernet(ctx->net)->commit_mutex);



		if (nft_array_may_resize(set) < 0) {

			iter->err = -ENOMEM;

			break;

		}

		nft_rbtree_do_walk(ctx, set, iter);

		break;

	case NFT_ITER_READ:
@@ -714,17 +760,26 @@ static int nft_rbtree_init(const struct nft_set *set, 
	BUILD_BUG_ON(offsetof(struct nft_rbtree_elem, priv) != 0);



	rwlock_init(&priv->lock);

	seqcount_rwlock_init(&priv->count, &priv->lock);

	priv->root = RB_ROOT;



	priv->array = NULL;

	priv->array_next = NULL;



	return 0;

}



static void __nft_array_free(struct nft_array *array)

{

	kvfree(array->intervals);

	kfree(array);

}



static void nft_rbtree_destroy(const struct nft_ctx *ctx,

			       const struct nft_set *set)

{

	struct nft_rbtree *priv = nft_set_priv(set);

	struct nft_rbtree_elem *rbe;

	struct nft_array *array;

	struct rb_node *node;



	while ((node = priv->root.rb_node) != NULL) {
@@ -732,6 +787,12 @@ static void nft_rbtree_destroy(const struct nft_ctx *ctx, 
		rbe = rb_entry(node, struct nft_rbtree_elem, node);

		nf_tables_set_elem_destroy(ctx, set, &rbe->priv);

	}



	array = rcu_dereference_protected(priv->array, true);

	if (array)

		__nft_array_free(array);

	if (priv->array_next)

		__nft_array_free(priv->array_next);

}



static bool nft_rbtree_estimate(const struct nft_set_desc *desc, u32 features,
@@ -752,12 +813,91 @@ static bool nft_rbtree_estimate(const struct nft_set_desc *desc, u32 features, 
	return true;

}



static void nft_array_free_rcu(struct rcu_head *rcu_head)

{

	struct nft_array *array = container_of(rcu_head, struct nft_array, rcu_head);



	__nft_array_free(array);

}



static void nft_rbtree_commit(struct nft_set *set)

{

	struct nft_rbtree *priv = nft_set_priv(set);

	struct nft_rbtree_elem *rbe, *prev_rbe;

	struct nft_array *old;

	u32 num_intervals = 0;

	struct rb_node *node;



	if (time_after_eq(jiffies, priv->last_gc + nft_set_gc_interval(set)))

		nft_rbtree_gc(set);



	/* No changes, skip, eg. elements updates only. */

	if (!priv->array_next)

		return;



	/* Reverse walk to create an array from smaller to largest interval. */

	node = rb_last(&priv->root);

	if (node)

		prev_rbe = rb_entry(node, struct nft_rbtree_elem, node);

	else

		prev_rbe = NULL;



	while (prev_rbe) {

		rbe = prev_rbe;



		if (nft_rbtree_interval_start(rbe))

			priv->array_next->intervals[num_intervals].from = &rbe->ext;

		else if (nft_rbtree_interval_end(rbe))

			priv->array_next->intervals[num_intervals++].to = &rbe->ext;



		if (num_intervals >= priv->array_next->max_intervals) {

			pr_warn_once("malformed interval set from userspace?");

			goto err_out;

		}



		node = rb_prev(node);

		if (!node)

			break;



		prev_rbe = rb_entry(node, struct nft_rbtree_elem, node);



		/* For anonymous sets, when adjacent ranges are found,

		 * the end element is not added to the set to pack the set

		 * representation. Use next start element to complete this

		 * interval.

		 */

		if (nft_rbtree_interval_start(rbe) &&

		    nft_rbtree_interval_start(prev_rbe) &&

		    priv->array_next->intervals[num_intervals].from)

			priv->array_next->intervals[num_intervals++].to = &prev_rbe->ext;



		if (num_intervals >= priv->array_next->max_intervals) {

			pr_warn_once("malformed interval set from userspace?");

			goto err_out;

		}

	}



	if (priv->array_next->intervals[num_intervals].from)

		num_intervals++;

err_out:

	priv->array_next->num_intervals = num_intervals;

	old = rcu_replace_pointer(priv->array, priv->array_next, true);

	priv->array_next = NULL;

	if (old)

		call_rcu(&old->rcu_head, nft_array_free_rcu);

}



static void nft_rbtree_abort(const struct nft_set *set)

{

	struct nft_rbtree *priv = nft_set_priv(set);

	struct nft_array *array_next;



	if (!priv->array_next)

		return;



	array_next = priv->array_next;

	priv->array_next = NULL;

	__nft_array_free(array_next);

}



static void nft_rbtree_gc_init(const struct nft_set *set)
@@ -821,6 +961,7 @@ const struct nft_set_type nft_set_rbtree_type = { 
		.flush		= nft_rbtree_flush,

		.activate	= nft_rbtree_activate,

		.commit		= nft_rbtree_commit,

		.abort		= nft_rbtree_abort,

		.gc_init	= nft_rbtree_gc_init,

		.lookup		= nft_rbtree_lookup,

		.walk		= nft_rbtree_walk,