[PATCH net 0/3] netfilter updates for net

[PATCH net 0/3] netfilter updates for net

[Florian Westphal]

Hello,

The following three patches fix regressions in the netfilter subsystem:

1. Reject attempts to repeatedly toggle the 'dormant' flag in a single
   transaction.  Doing so makes nf_tables lose track of the real state
   vs. the desired state.  This ends with an attempt to unregister hooks
   that were never registered in the first place, which yields a splat.

2. Fix element counting in the new nftables garbage collection infra
   that came with 6.5:  More than 255 expired elements wraps a counter
   which results in memory leak.

3. Since 6.4 ipset can BUG when a set is renamed while a CREATE command
   is in progress, fix from Jozsef Kadlecsik.

The following changes since commit 4e4b1798cc90e376b8b61d0098b4093898a32227:

  vxlan: Add missing entries to vxlan_get_size() (2023-09-20 09:00:54 +0100)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git tags/nf-23-09-20

for you to fetch changes up to 7433b6d2afd512d04398c73aa984d1e285be125b:

  netfilter: ipset: Fix race between IPSET_CMD_CREATE and IPSET_CMD_SWAP (2023-09-20 10:35:24 +0200)

Florian Westphal (2):
      netfilter: nf_tables: disable toggling dormant table state more than once
      netfilter: nf_tables: fix memleak when more than 255 elements expired

Jozsef Kadlecsik (1):
      netfilter: ipset: Fix race between IPSET_CMD_CREATE and IPSET_CMD_SWAP

 include/net/netfilter/nf_tables.h |  2 +-
 net/netfilter/ipset/ip_set_core.c | 12 ++++++++++--
 net/netfilter/nf_tables_api.c     | 14 ++++++++++++--
 3 files changed, 23 insertions(+), 5 deletions(-)
-- 
2.41.0

[PATCH net 1/3] netfilter: nf_tables: disable toggling dormant table state more than once

[Florian Westphal]

nft -f -<<EOF
add table ip t
add table ip t { flags dormant; }
add chain ip t c { type filter hook input priority 0; }
add table ip t
EOF

Triggers a splat from nf core on next table delete because we lose
track of right hook register state:

WARNING: CPU: 2 PID: 1597 at net/netfilter/core.c:501 __nf_unregister_net_hook
RIP: 0010:__nf_unregister_net_hook+0x41b/0x570
 nf_unregister_net_hook+0xb4/0xf0
 __nf_tables_unregister_hook+0x160/0x1d0
[..]

The above should have table in *active* state, but in fact no
hooks were registered.

Reject on/off/on games rather than attempting to fix this.

Fixes: 179d9ba5559a ("netfilter: nf_tables: fix table flag updates")
Reported-by: "Lee, Cherie-Anne" <cherie.lee@starlabs.sg>
Cc: Bing-Jhong Billy Jheng <billy@starlabs.sg>
Cc: info@starlabs.sg
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nf_tables_api.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d819b4d42962..a3680638ec60 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1219,6 +1219,10 @@ static int nf_tables_updtable(struct nft_ctx *ctx)
 	     flags & NFT_TABLE_F_OWNER))
 		return -EOPNOTSUPP;
 
+	/* No dormant off/on/off/on games in single transaction */
+	if (ctx->table->flags & __NFT_TABLE_F_UPDATE)
+		return -EINVAL;
+
 	trans = nft_trans_alloc(ctx, NFT_MSG_NEWTABLE,
 				sizeof(struct nft_trans_table));
 	if (trans == NULL)
-- 
2.41.0

Re: [PATCH net 1/3] netfilter: nf_tables: disable toggling dormant table state more than once

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by Florian Westphal <fw@strlen.de>:

On Wed, 20 Sep 2023 10:41:49 +0200 you wrote:
> nft -f -<<EOF
> add table ip t
> add table ip t { flags dormant; }
> add chain ip t c { type filter hook input priority 0; }
> add table ip t
> EOF
> 
> [...]

Here is the summary with links:
  - [net,1/3] netfilter: nf_tables: disable toggling dormant table state more than once
    https://git.kernel.org/netdev/net/c/c9bd26513b3a
  - [net,2/3] netfilter: nf_tables: fix memleak when more than 255 elements expired
    https://git.kernel.org/netdev/net/c/cf5000a7787c
  - [net,3/3] netfilter: ipset: Fix race between IPSET_CMD_CREATE and IPSET_CMD_SWAP
    https://git.kernel.org/netdev/net/c/7433b6d2afd5

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

[PATCH net 2/3] netfilter: nf_tables: fix memleak when more than 255 elements expired

[Florian Westphal]

When more than 255 elements expired we're supposed to switch to a new gc
container structure.

This never happens: u8 type will wrap before reaching the boundary
and nft_trans_gc_space() always returns true.

This means we recycle the initial gc container structure and
lose track of the elements that came before.

While at it, don't deref 'gc' after we've passed it to call_rcu.

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/net/netfilter/nf_tables.h |  2 +-
 net/netfilter/nf_tables_api.c     | 10 ++++++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index a4455f4995ab..7c816359d5a9 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1682,7 +1682,7 @@ struct nft_trans_gc {
 	struct net		*net;
 	struct nft_set		*set;
 	u32			seq;
-	u8			count;
+	u16			count;
 	void			*priv[NFT_TRANS_GC_BATCHCOUNT];
 	struct rcu_head		rcu;
 };
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a3680638ec60..4356189360fb 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9579,12 +9579,15 @@ static int nft_trans_gc_space(struct nft_trans_gc *trans)
 struct nft_trans_gc *nft_trans_gc_queue_async(struct nft_trans_gc *gc,
 					      unsigned int gc_seq, gfp_t gfp)
 {
+	struct nft_set *set;
+
 	if (nft_trans_gc_space(gc))
 		return gc;
 
+	set = gc->set;
 	nft_trans_gc_queue_work(gc);
 
-	return nft_trans_gc_alloc(gc->set, gc_seq, gfp);
+	return nft_trans_gc_alloc(set, gc_seq, gfp);
 }
 
 void nft_trans_gc_queue_async_done(struct nft_trans_gc *trans)
@@ -9599,15 +9602,18 @@ void nft_trans_gc_queue_async_done(struct nft_trans_gc *trans)
 
 struct nft_trans_gc *nft_trans_gc_queue_sync(struct nft_trans_gc *gc, gfp_t gfp)
 {
+	struct nft_set *set;
+
 	if (WARN_ON_ONCE(!lockdep_commit_lock_is_held(gc->net)))
 		return NULL;
 
 	if (nft_trans_gc_space(gc))
 		return gc;
 
+	set = gc->set;
 	call_rcu(&gc->rcu, nft_trans_gc_trans_free);
 
-	return nft_trans_gc_alloc(gc->set, 0, gfp);
+	return nft_trans_gc_alloc(set, 0, gfp);
 }
 
 void nft_trans_gc_queue_sync_done(struct nft_trans_gc *trans)
-- 
2.41.0

[PATCH net 3/3] netfilter: ipset: Fix race between IPSET_CMD_CREATE and IPSET_CMD_SWAP

[Florian Westphal]

From: Jozsef Kadlecsik <kadlec@netfilter.org>

Kyle Zeng reported that there is a race between IPSET_CMD_ADD and IPSET_CMD_SWAP
in netfilter/ip_set, which can lead to the invocation of `__ip_set_put` on a
wrong `set`, triggering the `BUG_ON(set->ref == 0);` check in it.

The race is caused by using the wrong reference counter, i.e. the ref counter instead
of ref_netlink.

Fixes: 24e227896bbf ("netfilter: ipset: Add schedule point in call_ad().")
Reported-by: Kyle Zeng <zengyhkyle@gmail.com>
Closes: https://lore.kernel.org/netfilter-devel/ZPZqetxOmH+w%2Fmyc@westworld/#r
Tested-by: Kyle Zeng <zengyhkyle@gmail.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/ipset/ip_set_core.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index e564b5174261..35d2f9c9ada0 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -682,6 +682,14 @@ __ip_set_put(struct ip_set *set)
 /* set->ref can be swapped out by ip_set_swap, netlink events (like dump) need
  * a separate reference counter
  */
+static void
+__ip_set_get_netlink(struct ip_set *set)
+{
+	write_lock_bh(&ip_set_ref_lock);
+	set->ref_netlink++;
+	write_unlock_bh(&ip_set_ref_lock);
+}
+
 static void
 __ip_set_put_netlink(struct ip_set *set)
 {
@@ -1693,11 +1701,11 @@ call_ad(struct net *net, struct sock *ctnl, struct sk_buff *skb,
 
 	do {
 		if (retried) {
-			__ip_set_get(set);
+			__ip_set_get_netlink(set);
 			nfnl_unlock(NFNL_SUBSYS_IPSET);
 			cond_resched();
 			nfnl_lock(NFNL_SUBSYS_IPSET);
-			__ip_set_put(set);
+			__ip_set_put_netlink(set);
 		}
 
 		ip_set_lock(set);
-- 
2.41.0