netdev - [PATCH 04/11] xfrm: Silence warnings triggerable by bad packets

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Message-ID: <20230815095310.3310160-5-steffen.klassert@secunet.com>
Date: Tue, 15 Aug 2023 11:53:03 +0200
From: Steffen Klassert <steffen.klassert@...unet.com>
To: David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>
CC: Herbert Xu <herbert@...dor.apana.org.au>, Steffen Klassert
	<steffen.klassert@...unet.com>, <netdev@...r.kernel.org>
Subject: [PATCH 04/11] xfrm: Silence warnings triggerable by bad packets

From: Herbert Xu <herbert@...dor.apana.org.au>

After the elimination of inner modes, a couple of warnings that
were previously unreachable can now be triggered by malformed
inbound packets.

Fix this by:

1. Moving the setting of skb->protocol into the decap functions.
2. Returning -EINVAL when unexpected protocol is seen.

Reported-by: Maciej Żenczykowski<maze@...gle.com>
Fixes: 5f24f41e8ea6 ("xfrm: Remove inner/outer modes from input path")
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Reviewed-by: Maciej Żenczykowski <maze@...gle.com>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
---
 net/xfrm/xfrm_input.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 815b38080401..d5ee96789d4b 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -180,6 +180,8 @@ static int xfrm4_remove_beet_encap(struct xfrm_state *x, struct sk_buff *skb)
 	int optlen = 0;
 	int err = -EINVAL;
 
+	skb->protocol = htons(ETH_P_IP);
+
 	if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) {
 		struct ip_beet_phdr *ph;
 		int phlen;
@@ -232,6 +234,8 @@ static int xfrm4_remove_tunnel_encap(struct xfrm_state *x, struct sk_buff *skb)
 {
 	int err = -EINVAL;
 
+	skb->protocol = htons(ETH_P_IP);
+
 	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 		goto out;
 
@@ -267,6 +271,8 @@ static int xfrm6_remove_tunnel_encap(struct xfrm_state *x, struct sk_buff *skb)
 {
 	int err = -EINVAL;
 
+	skb->protocol = htons(ETH_P_IPV6);
+
 	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 		goto out;
 
@@ -296,6 +302,8 @@ static int xfrm6_remove_beet_encap(struct xfrm_state *x, struct sk_buff *skb)
 	int size = sizeof(struct ipv6hdr);
 	int err;
 
+	skb->protocol = htons(ETH_P_IPV6);
+
 	err = skb_cow_head(skb, size + skb->mac_len);
 	if (err)
 		goto out;
@@ -346,6 +354,7 @@ xfrm_inner_mode_encap_remove(struct xfrm_state *x,
 			return xfrm6_remove_tunnel_encap(x, skb);
 		break;
 		}
+		return -EINVAL;
 	}
 
 	WARN_ON_ONCE(1);
@@ -366,19 +375,6 @@ static int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
 		return -EAFNOSUPPORT;
 	}
 
-	switch (XFRM_MODE_SKB_CB(skb)->protocol) {
-	case IPPROTO_IPIP:
-	case IPPROTO_BEETPH:
-		skb->protocol = htons(ETH_P_IP);
-		break;
-	case IPPROTO_IPV6:
-		skb->protocol = htons(ETH_P_IPV6);
-		break;
-	default:
-		WARN_ON_ONCE(1);
-		break;
-	}
-
 	return xfrm_inner_mode_encap_remove(x, skb);
 }
 
-- 
2.34.1