[PATCH net 0/6] Netfilter fixes for net

[PATCH net 0/6] Netfilter fixes for net

[Pablo Neira Ayuso]

Hi,

The following patchset contains Netfilter fixes for net:

1) Remove unused variable causing compilation warning in nft_set_rbtree,
   from Yang Li. This unused variable is a left over from previous
   merge window.

2) Possible return of uninitialized in nf_conntrack_bridge, from
   Linkui Xiao. This is there since nf_conntrack_bridge is available.

3) Fix incorrect pointer math in nft_byteorder, from Dan Carpenter.
   Problem has been there since 2016.

4) Fix bogus error in destroy set element command. Problem is there
   since this new destroy command was added.

5) Fix race condition in ipset between swap and destroy commands and
   add/del/test control plane. This problem is there since ipset was
   merged.

6) Split async and sync catchall GC in two function to fix unsafe
   iteration over RCU. This is a fix-for-fix that was included in
   the previous pull request.

Please, pull these changes from:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git nf-23-11-15

Thanks.

----------------------------------------------------------------

The following changes since commit 4b7b492615cf3017190f55444f7016812b66611d:

  af_unix: fix use-after-free in unix_stream_read_actor() (2023-11-14 10:51:13 +0100)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git tags/nf-23-11-15

for you to fetch changes up to 8837ba3e58ea1e3d09ae36db80b1e80853aada95:

  netfilter: nf_tables: split async and sync catchall in two functions (2023-11-14 16:16:21 +0100)

----------------------------------------------------------------
netfilter pull request 23-11-15

----------------------------------------------------------------
Dan Carpenter (1):
      netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval()

Jozsef Kadlecsik (1):
      netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test

Linkui Xiao (1):
      netfilter: nf_conntrack_bridge: initialize err to 0

Pablo Neira Ayuso (2):
      netfilter: nf_tables: bogus ENOENT when destroying element which does not exist
      netfilter: nf_tables: split async and sync catchall in two functions

Yang Li (1):
      netfilter: nft_set_rbtree: Remove unused variable nft_net

 include/net/netfilter/nf_tables.h          |  4 +-
 net/bridge/netfilter/nf_conntrack_bridge.c |  2 +-
 net/netfilter/ipset/ip_set_core.c          | 14 +++----
 net/netfilter/nf_tables_api.c              | 60 ++++++++++++++++--------------
 net/netfilter/nft_byteorder.c              |  5 ++-
 net/netfilter/nft_meta.c                   |  2 +-
 net/netfilter/nft_set_rbtree.c             |  2 -
 7 files changed, 47 insertions(+), 42 deletions(-)

[PATCH net 1/6] netfilter: nft_set_rbtree: Remove unused variable nft_net

[Pablo Neira Ayuso]

From: Yang Li <yang.lee@linux.alibaba.com>

The code that uses nft_net has been removed, and the nft_pernet function
is merely obtaining a reference to shared data through the net pointer.
The content of the net pointer is not modified or changed, so both of
them should be removed.

silence the warning:
net/netfilter/nft_set_rbtree.c:627:26: warning: variable ‘nft_net’ set but not used

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7103
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nft_set_rbtree.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c
index 6f1186abd47b..baa3fea4fe65 100644
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -624,14 +624,12 @@ static void nft_rbtree_gc(struct nft_set *set)
 {
 	struct nft_rbtree *priv = nft_set_priv(set);
 	struct nft_rbtree_elem *rbe, *rbe_end = NULL;
-	struct nftables_pernet *nft_net;
 	struct rb_node *node, *next;
 	struct nft_trans_gc *gc;
 	struct net *net;
 
 	set  = nft_set_container_of(priv);
 	net  = read_pnet(&set->net);
-	nft_net = nft_pernet(net);
 
 	gc = nft_trans_gc_alloc(set, 0, GFP_KERNEL);
 	if (!gc)
-- 
2.30.2

Re: [PATCH net 1/6] netfilter: nft_set_rbtree: Remove unused variable nft_net

[patchwork-bot+netdevbpf]

Hello:

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

On Wed, 15 Nov 2023 19:45:09 +0100 you wrote:
> From: Yang Li <yang.lee@linux.alibaba.com>
> 
> The code that uses nft_net has been removed, and the nft_pernet function
> is merely obtaining a reference to shared data through the net pointer.
> The content of the net pointer is not modified or changed, so both of
> them should be removed.
> 
> [...]

Here is the summary with links:
  - [net,1/6] netfilter: nft_set_rbtree: Remove unused variable nft_net
    https://git.kernel.org/netdev/net/c/67059b61597c
  - [net,2/6] netfilter: nf_conntrack_bridge: initialize err to 0
    https://git.kernel.org/netdev/net/c/a44af08e3d4d
  - [net,3/6] netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval()
    https://git.kernel.org/netdev/net/c/c301f0981fdd
  - [net,4/6] netfilter: nf_tables: bogus ENOENT when destroying element which does not exist
    https://git.kernel.org/netdev/net/c/a7d5a955bfa8
  - [net,5/6] netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test
    https://git.kernel.org/netdev/net/c/28628fa952fe
  - [net,6/6] netfilter: nf_tables: split async and sync catchall in two functions
    https://git.kernel.org/netdev/net/c/8837ba3e58ea

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

[PATCH net 2/6] netfilter: nf_conntrack_bridge: initialize err to 0

[Pablo Neira Ayuso]

From: Linkui Xiao <xiaolinkui@kylinos.cn>

K2CI reported a problem:

	consume_skb(skb);
	return err;
[nf_br_ip_fragment() error]  uninitialized symbol 'err'.

err is not initialized, because returning 0 is expected, initialize err
to 0.

Fixes: 3c171f496ef5 ("netfilter: bridge: add connection tracking system")
Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: Linkui Xiao <xiaolinkui@kylinos.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/bridge/netfilter/nf_conntrack_bridge.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
index b5c406a6e765..abb090f94ed2 100644
--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -37,7 +37,7 @@ static int nf_br_ip_fragment(struct net *net, struct sock *sk,
 	ktime_t tstamp = skb->tstamp;
 	struct ip_frag_state state;
 	struct iphdr *iph;
-	int err;
+	int err = 0;
 
 	/* for offloaded checksums cleanup checksum before fragmentation */
 	if (skb->ip_summed == CHECKSUM_PARTIAL &&
-- 
2.30.2

[PATCH net 3/6] netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval()

[Pablo Neira Ayuso]

From: Dan Carpenter <dan.carpenter@linaro.org>

The problem is in nft_byteorder_eval() where we are iterating through a
loop and writing to dst[0], dst[1], dst[2] and so on...  On each
iteration we are writing 8 bytes.  But dst[] is an array of u32 so each
element only has space for 4 bytes.  That means that every iteration
overwrites part of the previous element.

I spotted this bug while reviewing commit caf3ef7468f7 ("netfilter:
nf_tables: prevent OOB access in nft_byteorder_eval") which is a related
issue.  I think that the reason we have not detected this bug in testing
is that most of time we only write one element.

Fixes: ce1e7989d989 ("netfilter: nft_byteorder: provide 64bit le/be conversion")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_tables.h | 4 ++--
 net/netfilter/nft_byteorder.c     | 5 +++--
 net/netfilter/nft_meta.c          | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 3bbd13ab1ecf..b157c5cafd14 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -178,9 +178,9 @@ static inline __be32 nft_reg_load_be32(const u32 *sreg)
 	return *(__force __be32 *)sreg;
 }
 
-static inline void nft_reg_store64(u32 *dreg, u64 val)
+static inline void nft_reg_store64(u64 *dreg, u64 val)
 {
-	put_unaligned(val, (u64 *)dreg);
+	put_unaligned(val, dreg);
 }
 
 static inline u64 nft_reg_load64(const u32 *sreg)
diff --git a/net/netfilter/nft_byteorder.c b/net/netfilter/nft_byteorder.c
index e596d1a842f7..f6e791a68101 100644
--- a/net/netfilter/nft_byteorder.c
+++ b/net/netfilter/nft_byteorder.c
@@ -38,13 +38,14 @@ void nft_byteorder_eval(const struct nft_expr *expr,
 
 	switch (priv->size) {
 	case 8: {
+		u64 *dst64 = (void *)dst;
 		u64 src64;
 
 		switch (priv->op) {
 		case NFT_BYTEORDER_NTOH:
 			for (i = 0; i < priv->len / 8; i++) {
 				src64 = nft_reg_load64(&src[i]);
-				nft_reg_store64(&dst[i],
+				nft_reg_store64(&dst64[i],
 						be64_to_cpu((__force __be64)src64));
 			}
 			break;
@@ -52,7 +53,7 @@ void nft_byteorder_eval(const struct nft_expr *expr,
 			for (i = 0; i < priv->len / 8; i++) {
 				src64 = (__force __u64)
 					cpu_to_be64(nft_reg_load64(&src[i]));
-				nft_reg_store64(&dst[i], src64);
+				nft_reg_store64(&dst64[i], src64);
 			}
 			break;
 		}
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index f7da7c43333b..ba0d3683a45d 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -63,7 +63,7 @@ nft_meta_get_eval_time(enum nft_meta_keys key,
 {
 	switch (key) {
 	case NFT_META_TIME_NS:
-		nft_reg_store64(dest, ktime_get_real_ns());
+		nft_reg_store64((u64 *)dest, ktime_get_real_ns());
 		break;
 	case NFT_META_TIME_DAY:
 		nft_reg_store8(dest, nft_meta_weekday());
-- 
2.30.2

[PATCH net 4/6] netfilter: nf_tables: bogus ENOENT when destroying element which does not exist

[Pablo Neira Ayuso]

destroy element command bogusly reports ENOENT in case a set element
does not exist. ENOENT errors are skipped, however, err is still set
and propagated to userspace.

 # nft destroy element ip raw BLACKLIST { 1.2.3.4 }
 Error: Could not process rule: No such file or directory
 destroy element ip raw BLACKLIST { 1.2.3.4 }
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Fixes: f80a612dd77c ("netfilter: nf_tables: add support to destroy operation")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a761ee6796f6..debea1c67701 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -7263,10 +7263,11 @@ static int nf_tables_delsetelem(struct sk_buff *skb,
 
 		if (err < 0) {
 			NL_SET_BAD_ATTR(extack, attr);
-			break;
+			return err;
 		}
 	}
-	return err;
+
+	return 0;
 }
 
 /*
-- 
2.30.2

[PATCH net 5/6] netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test

[Pablo Neira Ayuso]

From: Jozsef Kadlecsik <kadlec@netfilter.org>

Linkui Xiao reported that there's a race condition when ipset swap and destroy is
called, which can lead to crash in add/del/test element operations. Swap then
destroy are usual operations to replace a set with another one in a production
system. The issue can in some cases be reproduced with the script:

ipset create hash_ip1 hash:net family inet hashsize 1024 maxelem 1048576
ipset add hash_ip1 172.20.0.0/16
ipset add hash_ip1 192.168.0.0/16
iptables -A INPUT -m set --match-set hash_ip1 src -j ACCEPT
while [ 1 ]
do
	# ... Ongoing traffic...
        ipset create hash_ip2 hash:net family inet hashsize 1024 maxelem 1048576
        ipset add hash_ip2 172.20.0.0/16
        ipset swap hash_ip1 hash_ip2
        ipset destroy hash_ip2
        sleep 0.05
done

In the race case the possible order of the operations are

	CPU0			CPU1
	ip_set_test
				ipset swap hash_ip1 hash_ip2
				ipset destroy hash_ip2
	hash_net_kadt

Swap replaces hash_ip1 with hash_ip2 and then destroy removes hash_ip2 which
is the original hash_ip1. ip_set_test was called on hash_ip1 and because destroy
removed it, hash_net_kadt crashes.

The fix is to force ip_set_swap() to wait for all readers to finish accessing the
old set pointers by calling synchronize_rcu().

The first version of the patch was written by Linkui Xiao <xiaolinkui@kylinos.cn>.

v2: synchronize_rcu() is moved into ip_set_swap() in order not to burden
    ip_set_destroy() unnecessarily when all sets are destroyed.
v3: Florian Westphal pointed out that all netfilter hooks run with rcu_read_lock() held
    and em_ipset.c wraps the entire ip_set_test() in rcu read lock/unlock pair.
    So there's no need to extend the rcu read locked area in ipset itself.

Closes: https://lore.kernel.org/all/69e7963b-e7f8-3ad0-210-7b86eebf7f78@netfilter.org/
Reported by: Linkui Xiao <xiaolinkui@kylinos.cn>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/ipset/ip_set_core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index 35d2f9c9ada0..4c133e06be1d 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -61,6 +61,8 @@ MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_IPSET);
 	ip_set_dereference((inst)->ip_set_list)[id]
 #define ip_set_ref_netlink(inst,id)	\
 	rcu_dereference_raw((inst)->ip_set_list)[id]
+#define ip_set_dereference_nfnl(p)	\
+	rcu_dereference_check(p, lockdep_nfnl_is_held(NFNL_SUBSYS_IPSET))
 
 /* The set types are implemented in modules and registered set types
  * can be found in ip_set_type_list. Adding/deleting types is
@@ -708,15 +710,10 @@ __ip_set_put_netlink(struct ip_set *set)
 static struct ip_set *
 ip_set_rcu_get(struct net *net, ip_set_id_t index)
 {
-	struct ip_set *set;
 	struct ip_set_net *inst = ip_set_pernet(net);
 
-	rcu_read_lock();
-	/* ip_set_list itself needs to be protected */
-	set = rcu_dereference(inst->ip_set_list)[index];
-	rcu_read_unlock();
-
-	return set;
+	/* ip_set_list and the set pointer need to be protected */
+	return ip_set_dereference_nfnl(inst->ip_set_list)[index];
 }
 
 static inline void
@@ -1397,6 +1394,9 @@ static int ip_set_swap(struct sk_buff *skb, const struct nfnl_info *info,
 	ip_set(inst, to_id) = from;
 	write_unlock_bh(&ip_set_ref_lock);
 
+	/* Make sure all readers of the old set pointers are completed. */
+	synchronize_rcu();
+
 	return 0;
 }
 
-- 
2.30.2

[PATCH net 6/6] netfilter: nf_tables: split async and sync catchall in two functions

[Pablo Neira Ayuso]

list_for_each_entry_safe() does not work for the async case which runs
under RCU, therefore, split GC logic for catchall in two functions
instead, one for each of the sync and async GC variants.

The catchall sync GC variant never sees a _DEAD bit set on ever, thus,
this handling is removed in such case, moreover, allocate GC sync batch
via GFP_KERNEL.

Fixes: 93995bf4af2c ("netfilter: nf_tables: remove catchall element in GC sync path")
Reported-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 55 +++++++++++++++++++----------------
 1 file changed, 30 insertions(+), 25 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index debea1c67701..c0a42989b982 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9680,16 +9680,14 @@ void nft_trans_gc_queue_sync_done(struct nft_trans_gc *trans)
 	call_rcu(&trans->rcu, nft_trans_gc_trans_free);
 }
 
-static struct nft_trans_gc *nft_trans_gc_catchall(struct nft_trans_gc *gc,
-						  unsigned int gc_seq,
-						  bool sync)
+struct nft_trans_gc *nft_trans_gc_catchall_async(struct nft_trans_gc *gc,
+						 unsigned int gc_seq)
 {
-	struct nft_set_elem_catchall *catchall, *next;
+	struct nft_set_elem_catchall *catchall;
 	const struct nft_set *set = gc->set;
-	struct nft_elem_priv *elem_priv;
 	struct nft_set_ext *ext;
 
-	list_for_each_entry_safe(catchall, next, &set->catchall_list, list) {
+	list_for_each_entry_rcu(catchall, &set->catchall_list, list) {
 		ext = nft_set_elem_ext(set, catchall->elem);
 
 		if (!nft_set_elem_expired(ext))
@@ -9699,35 +9697,42 @@ static struct nft_trans_gc *nft_trans_gc_catchall(struct nft_trans_gc *gc,
 
 		nft_set_elem_dead(ext);
 dead_elem:
-		if (sync)
-			gc = nft_trans_gc_queue_sync(gc, GFP_ATOMIC);
-		else
-			gc = nft_trans_gc_queue_async(gc, gc_seq, GFP_ATOMIC);
-
+		gc = nft_trans_gc_queue_async(gc, gc_seq, GFP_ATOMIC);
 		if (!gc)
 			return NULL;
 
-		elem_priv = catchall->elem;
-		if (sync) {
-			nft_setelem_data_deactivate(gc->net, gc->set, elem_priv);
-			nft_setelem_catchall_destroy(catchall);
-		}
-
-		nft_trans_gc_elem_add(gc, elem_priv);
+		nft_trans_gc_elem_add(gc, catchall->elem);
 	}
 
 	return gc;
 }
 
-struct nft_trans_gc *nft_trans_gc_catchall_async(struct nft_trans_gc *gc,
-						 unsigned int gc_seq)
-{
-	return nft_trans_gc_catchall(gc, gc_seq, false);
-}
-
 struct nft_trans_gc *nft_trans_gc_catchall_sync(struct nft_trans_gc *gc)
 {
-	return nft_trans_gc_catchall(gc, 0, true);
+	struct nft_set_elem_catchall *catchall, *next;
+	const struct nft_set *set = gc->set;
+	struct nft_elem_priv *elem_priv;
+	struct nft_set_ext *ext;
+
+	WARN_ON_ONCE(!lockdep_commit_lock_is_held(gc->net));
+
+	list_for_each_entry_safe(catchall, next, &set->catchall_list, list) {
+		ext = nft_set_elem_ext(set, catchall->elem);
+
+		if (!nft_set_elem_expired(ext))
+			continue;
+
+		gc = nft_trans_gc_queue_sync(gc, GFP_KERNEL);
+		if (!gc)
+			return NULL;
+
+		elem_priv = catchall->elem;
+		nft_setelem_data_deactivate(gc->net, gc->set, elem_priv);
+		nft_setelem_catchall_destroy(catchall);
+		nft_trans_gc_elem_add(gc, elem_priv);
+	}
+
+	return gc;
 }
 
 static void nf_tables_module_autoload_cleanup(struct net *net)
-- 
2.30.2