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xfrm: drop ESP-in-TCP packets with no ingress device

PATCH Applied Ren Wei 2 participants 2 messages Jul 18 – Jul 23 1 message not in the archive

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A message that is not in the archive (sent off-list or not yet received): [email protected]

Ren Wei

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#1 lore raw

PATCH 1/1 xfrm: drop ESP-in-TCP packets with no ingress device

From: Zhiling Zou <[email protected]>

ESP-in-TCP receives records through the TCP strparser. handle_esp() restores skb->dev from the saved skb_iif before passing the packet into the XFRM input path.

Queued TCP data can be processed after the original ingress device has been removed, for example during veth or net namespace teardown. In that case dev_get_by_index_rcu() returns NULL. The XFRM IPv4 and IPv6 input paths both expect skb->dev to be valid while building the route lookup, so queued ESP-in-TCP data can dereference a NULL device.

Drop the packet if the saved ingress device can no longer be resolved. Such a packet can no longer be routed through the normal XFRM receive path, and this preserves the existing behaviour for packets whose ingress device still exists.

Fixes e27cca96cd68 ("xfrm: add espintcp (RFC 8229)")
Cc [email protected]
Reported-by Vega <[email protected]>
Signed-off-by Zhiling Zou <[email protected]>
Assisted-by Codex:gpt-5.4
Reviewed-by Ren Wei <[email protected]>
---
 net/xfrm/espintcp.c | 6 ++++++
 1 file changed, 6 insertions(+)
net/xfrm/espintcp.c +6 -0
index 374e1b964438..fc01ce89492a 100644
@@ -37,6 +37,11 @@ static void handle_esp(struct sk_buff *skb, struct sock *sk)
 
 	rcu_read_lock();
 	skb->dev = dev_get_by_index_rcu(sock_net(sk), skb->skb_iif);
+	if (!skb->dev) {
+		XFRM_INC_STATS(sock_net(sk), LINUX_MIB_XFRMINERROR);
+		kfree_skb(skb);
+		goto out;
+	}
 	local_bh_disable();
 #if IS_ENABLED(CONFIG_IPV6)
 	if (sk->sk_family == AF_INET6)

@@ -45,6 +50,7 @@ static void handle_esp(struct sk_buff *skb, struct sock *sk)
 #endif
 		xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, TCP_ENCAP_ESPINTCP);
 	local_bh_enable();
+out:
 	rcu_read_unlock();
 }
Signature · 1 line
2.43.0
maintainer Applied
#2 lore raw
Quoted 17 lines · Ren Wei

From: Zhiling Zou <[email protected]>

ESP-in-TCP receives records through the TCP strparser. handle_esp() restores skb->dev from the saved skb_iif before passing the packet into the XFRM input path.

Queued TCP data can be processed after the original ingress device has been removed, for example during veth or net namespace teardown. In that case dev_get_by_index_rcu() returns NULL. The XFRM IPv4 and IPv6 input paths both expect skb->dev to be valid while building the route lookup, so queued ESP-in-TCP data can dereference a NULL device.

Drop the packet if the saved ingress device can no longer be resolved. Such a packet can no longer be routed through the normal XFRM receive path, and this preserves the existing behaviour for packets whose ingress device still exists.

Quoted 6 lines
Fixes e27cca96cd68 ("xfrm: add espintcp (RFC 8229)")
Cc [email protected]
Reported-by Vega <[email protected]>
Signed-off-by Zhiling Zou <[email protected]>
Assisted-by Codex:gpt-5.4
Reviewed-by Ren Wei <[email protected]>

Applied, thanks a lot!