[PATCH 6.1 168/197] xfrm: Silence warnings triggerable by bad packets

Greg Kroah-Hartman
2024-02-20T21:08:16Z

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

commit 57010b8ece2821a1fdfdba2197d14a022f3769db upstream.

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

--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -180,6 +180,8 @@ static int xfrm4_remove_beet_encap(struc
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(str
{
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(str
{
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(struc
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
return xfrm6_remove_tunnel_encap(x, skb);
break;
}
+ return -EINVAL;
}

WARN_ON_ONCE(1);
@@ -366,19 +375,6 @@ static int xfrm_prepare_input(struct xfr
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);
}