diff mbox series

[net,1/5] netfilter: nf_tables: don't skip expired elements during walk

Message ID 20230810070830.24064-2-pablo@netfilter.org
State Not Applicable, archived
Headers show
Series [net,1/5] netfilter: nf_tables: don't skip expired elements during walk | expand

Commit Message

Pablo Neira Ayuso Aug. 10, 2023, 7:08 a.m. UTC 
From: Florian Westphal <fw@strlen.de>

There is an asymmetry between commit/abort and preparation phase if the
following conditions are met:

1. set is a verdict map ("1.2.3.4 : jump foo")
2. timeouts are enabled

In this case, following sequence is problematic:

1. element E in set S refers to chain C
2. userspace requests removal of set S
3. kernel does a set walk to decrement chain->use count for all elements
   from preparation phase
4. kernel does another set walk to remove elements from the commit phase
   (or another walk to do a chain->use increment for all elements from
    abort phase)

If E has already expired in 1), it will be ignored during list walk, so its use count
won't have been changed.

Then, when set is culled, ->destroy callback will zap the element via
nf_tables_set_elem_destroy(), but this function is only safe for
elements that have been deactivated earlier from the preparation phase:
lack of earlier deactivate removes the element but leaks the chain use
count, which results in a WARN splat when the chain gets removed later,
plus a leak of the nft_chain structure.

Update pipapo_get() not to skip expired elements, otherwise flush
command reports bogus ENOENT errors.

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Fixes: 8d8540c4f5e0 ("netfilter: nft_set_rbtree: add timeout support")
Fixes: 9d0982927e79 ("netfilter: nft_hash: add support for timeouts")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c  |  4 ++++
 net/netfilter/nft_set_hash.c   |  2 --
 net/netfilter/nft_set_pipapo.c | 18 ++++++++++++------
 net/netfilter/nft_set_rbtree.c |  2 --
 4 files changed, 16 insertions(+), 10 deletions(-)

Comments

patchwork-bot+netdevbpf@kernel.org Aug. 10, 2023, 6 p.m. UTC | #1 
Hello:

This series was applied to netdev/net.git (main)
by Pablo Neira Ayuso <pablo@netfilter.org>:

On Thu, 10 Aug 2023 09:08:26 +0200 you wrote:
> From: Florian Westphal <fw@strlen.de>
> 
> There is an asymmetry between commit/abort and preparation phase if the
> following conditions are met:
> 
> 1. set is a verdict map ("1.2.3.4 : jump foo")
> 2. timeouts are enabled
> 
> [...]

Here is the summary with links:
  - [net,1/5] netfilter: nf_tables: don't skip expired elements during walk
    https://git.kernel.org/netdev/net/c/24138933b97b
  - [net,2/5] netfilter: nf_tables: GC transaction API to avoid race with control plane
    https://git.kernel.org/netdev/net/c/5f68718b34a5
  - [net,3/5] netfilter: nf_tables: adapt set backend to use GC transaction API
    https://git.kernel.org/netdev/net/c/f6c383b8c31a
  - [net,4/5] netfilter: nft_set_hash: mark set element as dead when deleting from packet path
    https://git.kernel.org/netdev/net/c/c92db3030492
  - [net,5/5] netfilter: nf_tables: remove busy mark and gc batch API
    https://git.kernel.org/netdev/net/c/a2dd0233cbc4

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d3c6ecd1f5a6..b4321869e5c6 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5602,8 +5602,12 @@  static int nf_tables_dump_setelem(const struct nft_ctx *ctx,
 				  const struct nft_set_iter *iter,
 				  struct nft_set_elem *elem)
 {
+	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
 	struct nft_set_dump_args *args;
 
+	if (nft_set_elem_expired(ext))
+		return 0;
+
 	args = container_of(iter, struct nft_set_dump_args, iter);
 	return nf_tables_fill_setelem(args->skb, set, elem, args->reset);
 }
diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c
index 0b73cb0e752f..24caa31fa231 100644
--- a/net/netfilter/nft_set_hash.c
+++ b/net/netfilter/nft_set_hash.c
@@ -278,8 +278,6 @@  static void nft_rhash_walk(const struct nft_ctx *ctx, struct nft_set *set,
 
 		if (iter->count < iter->skip)
 			goto cont;
-		if (nft_set_elem_expired(&he->ext))
-			goto cont;
 		if (!nft_set_elem_active(&he->ext, iter->genmask))
 			goto cont;
 
diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
index 49915a2a58eb..d54784ea465b 100644
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -566,8 +566,7 @@  static struct nft_pipapo_elem *pipapo_get(const struct net *net,
 			goto out;
 
 		if (last) {
-			if (nft_set_elem_expired(&f->mt[b].e->ext) ||
-			    (genmask &&
+			if ((genmask &&
 			     !nft_set_elem_active(&f->mt[b].e->ext, genmask)))
 				goto next_match;
 
@@ -601,8 +600,17 @@  static struct nft_pipapo_elem *pipapo_get(const struct net *net,
 static void *nft_pipapo_get(const struct net *net, const struct nft_set *set,
 			    const struct nft_set_elem *elem, unsigned int flags)
 {
-	return pipapo_get(net, set, (const u8 *)elem->key.val.data,
-			  nft_genmask_cur(net));
+	struct nft_pipapo_elem *ret;
+
+	ret = pipapo_get(net, set, (const u8 *)elem->key.val.data,
+			 nft_genmask_cur(net));
+	if (IS_ERR(ret))
+		return ret;
+
+	if (nft_set_elem_expired(&ret->ext))
+		return ERR_PTR(-ENOENT);
+
+	return ret;
 }
 
 /**
@@ -2005,8 +2013,6 @@  static void nft_pipapo_walk(const struct nft_ctx *ctx, struct nft_set *set,
 			goto cont;
 
 		e = f->mt[r].e;
-		if (nft_set_elem_expired(&e->ext))
-			goto cont;
 
 		elem.priv = e;
 
diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c
index 8d73fffd2d09..39956e5341c9 100644
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -552,8 +552,6 @@  static void nft_rbtree_walk(const struct nft_ctx *ctx,
 
 		if (iter->count < iter->skip)
 			goto cont;
-		if (nft_set_elem_expired(&rbe->ext))
-			goto cont;
 		if (!nft_set_elem_active(&rbe->ext, iter->genmask))
 			goto cont;