[PATCH net 0/2] Netfilter fixes for net

[PATCH net 0/2] Netfilter fixes for net

[Pablo Neira Ayuso]

Hi,

The following patchset contains late Netfilter fixes for net:

1) Set on IPS_CONFIRMED before change_status() otherwise EBUSY is
   bogusly hit. This bug was introduced in the 6.3 release cycle.

2) Fix nfnetlink_queue conntrack support: Set/dump timeout
   accordingly for unconfirmed conntrack entries. Make sure this
   is done after IPS_CONFIRMED is set on. This is an old bug, it
   happens since the introduction of this feature.

Please, pull these changes from:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git

Thanks.

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

The following changes since commit 92e8c732d8518588ac34b4cb3feaf37d2cb87555:

  Merge git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf (2023-04-18 20:46:31 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git HEAD

for you to fetch changes up to 73db1b8f2bb6725b7391e85aab41fdf592b3c0c1:

  netfilter: conntrack: fix wrong ct->timeout value (2023-04-19 12:08:38 +0200)

----------------------------------------------------------------
Pablo Neira Ayuso (1):
      netfilter: conntrack: restore IPS_CONFIRMED out of nf_conntrack_hash_check_insert()

Tzung-Bi Shih (1):
      netfilter: conntrack: fix wrong ct->timeout value

 include/net/netfilter/nf_conntrack_core.h |  6 +++++-
 net/netfilter/nf_conntrack_bpf.c          |  1 +
 net/netfilter/nf_conntrack_core.c         |  1 -
 net/netfilter/nf_conntrack_netlink.c      | 16 ++++++++++++----
 4 files changed, 18 insertions(+), 6 deletions(-)

[PATCH net 1/2] netfilter: conntrack: restore IPS_CONFIRMED out of nf_conntrack_hash_check_insert()

[Pablo Neira Ayuso]

e6d57e9ff0ae ("netfilter: conntrack: fix rmmod double-free race")
consolidates IPS_CONFIRMED bit set in nf_conntrack_hash_check_insert().
However, this breaks ctnetlink:

 # conntrack -I -p tcp --timeout 123 --src 1.2.3.4 --dst 5.6.7.8 --state ESTABLISHED --sport 1 --dport 4 -u SEEN_REPLY
 conntrack v1.4.6 (conntrack-tools): Operation failed: Device or resource busy

This is a partial revert of the aforementioned commit to restore
IPS_CONFIRMED.

Fixes: e6d57e9ff0ae ("netfilter: conntrack: fix rmmod double-free race")
Reported-by: Stéphane Graber <stgraber@stgraber.org>
Tested-by: Stéphane Graber <stgraber@stgraber.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_conntrack_bpf.c     | 1 +
 net/netfilter/nf_conntrack_core.c    | 1 -
 net/netfilter/nf_conntrack_netlink.c | 3 +++
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c
index cd99e6dc1f35..34913521c385 100644
--- a/net/netfilter/nf_conntrack_bpf.c
+++ b/net/netfilter/nf_conntrack_bpf.c
@@ -381,6 +381,7 @@ __bpf_kfunc struct nf_conn *bpf_ct_insert_entry(struct nf_conn___init *nfct_i)
 	struct nf_conn *nfct = (struct nf_conn *)nfct_i;
 	int err;
 
+	nfct->status |= IPS_CONFIRMED;
 	err = nf_conntrack_hash_check_insert(nfct);
 	if (err < 0) {
 		nf_conntrack_free(nfct);
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index c6a6a6099b4e..7ba6ab9b54b5 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -932,7 +932,6 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct)
 		goto out;
 	}
 
-	ct->status |= IPS_CONFIRMED;
 	smp_wmb();
 	/* The caller holds a reference to this object */
 	refcount_set(&ct->ct_general.use, 2);
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index bfc3aaa2c872..d3ee18854698 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -2316,6 +2316,9 @@ ctnetlink_create_conntrack(struct net *net,
 	nfct_seqadj_ext_add(ct);
 	nfct_synproxy_ext_add(ct);
 
+	/* we must add conntrack extensions before confirmation. */
+	ct->status |= IPS_CONFIRMED;
+
 	if (cda[CTA_STATUS]) {
 		err = ctnetlink_change_status(ct, cda);
 		if (err < 0)
-- 
2.30.2

[PATCH net 2/2] netfilter: conntrack: fix wrong ct->timeout value

[Pablo Neira Ayuso]

From: Tzung-Bi Shih <tzungbi@kernel.org>

(struct nf_conn)->timeout is an interval before the conntrack
confirmed.  After confirmed, it becomes a timestamp.

It is observed that timeout of an unconfirmed conntrack:
- Set by calling ctnetlink_change_timeout(). As a result,
  `nfct_time_stamp` was wrongly added to `ct->timeout` twice.
- Get by calling ctnetlink_dump_timeout(). As a result,
  `nfct_time_stamp` was wrongly subtracted.

Call Trace:
 <TASK>
 dump_stack_lvl
 ctnetlink_dump_timeout
 __ctnetlink_glue_build
 ctnetlink_glue_build
 __nfqnl_enqueue_packet
 nf_queue
 nf_hook_slow
 ip_mc_output
 ? __pfx_ip_finish_output
 ip_send_skb
 ? __pfx_dst_output
 udp_send_skb
 udp_sendmsg
 ? __pfx_ip_generic_getfrag
 sock_sendmsg

Separate the 2 cases in:
- Setting `ct->timeout` in __nf_ct_set_timeout().
- Getting `ct->timeout` in ctnetlink_dump_timeout().

Pablo appends:

Update ctnetlink to set up the timeout _after_ the IPS_CONFIRMED flag is
set on, otherwise conntrack creation via ctnetlink breaks.

Note that the problem described in this patch occurs since the
introduction of the nfnetlink_queue conntrack support, select a
sufficiently old Fixes: tag for -stable kernel to pick up this fix.

Fixes: a4b4766c3ceb ("netfilter: nfnetlink_queue: rename related to nfqueue attaching conntrack info")
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_conntrack_core.h |  6 +++++-
 net/netfilter/nf_conntrack_netlink.c      | 13 +++++++++----
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h
index 71d1269fe4d4..3384859a8921 100644
--- a/include/net/netfilter/nf_conntrack_core.h
+++ b/include/net/netfilter/nf_conntrack_core.h
@@ -89,7 +89,11 @@ static inline void __nf_ct_set_timeout(struct nf_conn *ct, u64 timeout)
 {
 	if (timeout > INT_MAX)
 		timeout = INT_MAX;
-	WRITE_ONCE(ct->timeout, nfct_time_stamp + (u32)timeout);
+
+	if (nf_ct_is_confirmed(ct))
+		WRITE_ONCE(ct->timeout, nfct_time_stamp + (u32)timeout);
+	else
+		ct->timeout = (u32)timeout;
 }
 
 int __nf_ct_change_timeout(struct nf_conn *ct, u64 cta_timeout);
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index d3ee18854698..6f3b23a6653c 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -176,7 +176,12 @@ static int ctnetlink_dump_status(struct sk_buff *skb, const struct nf_conn *ct)
 static int ctnetlink_dump_timeout(struct sk_buff *skb, const struct nf_conn *ct,
 				  bool skip_zero)
 {
-	long timeout = nf_ct_expires(ct) / HZ;
+	long timeout;
+
+	if (nf_ct_is_confirmed(ct))
+		timeout = nf_ct_expires(ct) / HZ;
+	else
+		timeout = ct->timeout / HZ;
 
 	if (skip_zero && timeout == 0)
 		return 0;
@@ -2253,9 +2258,6 @@ ctnetlink_create_conntrack(struct net *net,
 	if (!cda[CTA_TIMEOUT])
 		goto err1;
 
-	timeout = (u64)ntohl(nla_get_be32(cda[CTA_TIMEOUT])) * HZ;
-	__nf_ct_set_timeout(ct, timeout);
-
 	rcu_read_lock();
  	if (cda[CTA_HELP]) {
 		char *helpname = NULL;
@@ -2319,6 +2321,9 @@ ctnetlink_create_conntrack(struct net *net,
 	/* we must add conntrack extensions before confirmation. */
 	ct->status |= IPS_CONFIRMED;
 
+	timeout = (u64)ntohl(nla_get_be32(cda[CTA_TIMEOUT])) * HZ;
+	__nf_ct_set_timeout(ct, timeout);
+
 	if (cda[CTA_STATUS]) {
 		err = ctnetlink_change_status(ct, cda);
 		if (err < 0)
-- 
2.30.2

Re: [PATCH net 0/2] Netfilter fixes for net

[Jakub Kicinski]

On Thu, 20 Apr 2023 19:06:55 +0200 Pablo Neira Ayuso wrote:
> 1) Set on IPS_CONFIRMED before change_status() otherwise EBUSY is
>    bogusly hit. This bug was introduced in the 6.3 release cycle.
> 
> 2) Fix nfnetlink_queue conntrack support: Set/dump timeout
>    accordingly for unconfirmed conntrack entries. Make sure this
>    is done after IPS_CONFIRMED is set on. This is an old bug, it
>    happens since the introduction of this feature.

It missed our PR anyway so please resend with a signed tag.

[PATCH net 1/2] netfilter: conntrack: restore IPS_CONFIRMED out of nf_conntrack_hash_check_insert()

[Pablo Neira Ayuso]

e6d57e9ff0ae ("netfilter: conntrack: fix rmmod double-free race")
consolidates IPS_CONFIRMED bit set in nf_conntrack_hash_check_insert().
However, this breaks ctnetlink:

 # conntrack -I -p tcp --timeout 123 --src 1.2.3.4 --dst 5.6.7.8 --state ESTABLISHED --sport 1 --dport 4 -u SEEN_REPLY
 conntrack v1.4.6 (conntrack-tools): Operation failed: Device or resource busy

This is a partial revert of the aforementioned commit to restore
IPS_CONFIRMED.

Fixes: e6d57e9ff0ae ("netfilter: conntrack: fix rmmod double-free race")
Reported-by: Stéphane Graber <stgraber@stgraber.org>
Tested-by: Stéphane Graber <stgraber@stgraber.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_conntrack_bpf.c     | 1 +
 net/netfilter/nf_conntrack_core.c    | 1 -
 net/netfilter/nf_conntrack_netlink.c | 3 +++
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c
index cd99e6dc1f35..34913521c385 100644
--- a/net/netfilter/nf_conntrack_bpf.c
+++ b/net/netfilter/nf_conntrack_bpf.c
@@ -381,6 +381,7 @@ __bpf_kfunc struct nf_conn *bpf_ct_insert_entry(struct nf_conn___init *nfct_i)
 	struct nf_conn *nfct = (struct nf_conn *)nfct_i;
 	int err;
 
+	nfct->status |= IPS_CONFIRMED;
 	err = nf_conntrack_hash_check_insert(nfct);
 	if (err < 0) {
 		nf_conntrack_free(nfct);
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index c6a6a6099b4e..7ba6ab9b54b5 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -932,7 +932,6 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct)
 		goto out;
 	}
 
-	ct->status |= IPS_CONFIRMED;
 	smp_wmb();
 	/* The caller holds a reference to this object */
 	refcount_set(&ct->ct_general.use, 2);
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index bfc3aaa2c872..d3ee18854698 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -2316,6 +2316,9 @@ ctnetlink_create_conntrack(struct net *net,
 	nfct_seqadj_ext_add(ct);
 	nfct_synproxy_ext_add(ct);
 
+	/* we must add conntrack extensions before confirmation. */
+	ct->status |= IPS_CONFIRMED;
+
 	if (cda[CTA_STATUS]) {
 		err = ctnetlink_change_status(ct, cda);
 		if (err < 0)
-- 
2.30.2

Re: [PATCH net 1/2] netfilter: conntrack: restore IPS_CONFIRMED out of nf_conntrack_hash_check_insert()

[patchwork-bot+netdevbpf]

Hello:

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

On Fri, 21 Apr 2023 12:56:59 +0200 you wrote:
> e6d57e9ff0ae ("netfilter: conntrack: fix rmmod double-free race")
> consolidates IPS_CONFIRMED bit set in nf_conntrack_hash_check_insert().
> However, this breaks ctnetlink:
> 
>  # conntrack -I -p tcp --timeout 123 --src 1.2.3.4 --dst 5.6.7.8 --state ESTABLISHED --sport 1 --dport 4 -u SEEN_REPLY
>  conntrack v1.4.6 (conntrack-tools): Operation failed: Device or resource busy
> 
> [...]

Here is the summary with links:
  - [net,1/2] netfilter: conntrack: restore IPS_CONFIRMED out of nf_conntrack_hash_check_insert()
    https://git.kernel.org/netdev/net/c/2cdaa3eefed8
  - [net,2/2] netfilter: conntrack: fix wrong ct->timeout value
    https://git.kernel.org/netdev/net/c/73db1b8f2bb6

You are awesome, thank you!
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