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net: mctp: don't use source cb data when forwarding, ensure pkt_type is set

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In the output path, only check the skb->cb data when we know it's from
a local socket; input packets will have source address information there
instead.

In order to detect when we're forwarding, set skb->pkt_type on
input/output.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://patch.msgid.link/20250702-dev-forwarding-v5-1-1468191da8a4@codeconstruct.com.au
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Jeremy Kerr
2025-07-02 14:20:01 +08:00
committed by Paolo Abeni
parent 05cc60ef27
commit e0f3c79cc0
1 changed files with 12 additions and 1 deletions
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13
net/mctp/route.c
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@@ -392,6 +392,9 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
*/
skb_orphan(skb);
if (skb->pkt_type == PACKET_OUTGOING)
skb->pkt_type = PACKET_LOOPBACK;
/* ensure we have enough data for a header and a type */
if (skb->len < sizeof(struct mctp_hdr) + 1)
goto out;
@@ -578,7 +581,13 @@ static int mctp_route_output(struct mctp_route *route, struct sk_buff *skb)
return -EMSGSIZE;
}
if (cb->ifindex) {
/* If we're forwarding, we don't want to use the input path's cb,
* as it holds the *source* hardware addressing information.
*
* We will have a PACKET_HOST skb from the dev, or PACKET_OUTGOING
* from a socket; only use cb in the latter case.
*/
if (skb->pkt_type == PACKET_OUTGOING && cb->ifindex) {
/* direct route; use the hwaddr we stashed in sendmsg */
if (cb->halen != skb->dev->addr_len) {
/* sanity check, sendmsg should have already caught this */
@@ -587,6 +596,7 @@ static int mctp_route_output(struct mctp_route *route, struct sk_buff *skb)
}
daddr = cb->haddr;
} else {
skb->pkt_type = PACKET_OUTGOING;
/* If lookup fails let the device handle daddr==NULL */
if (mctp_neigh_lookup(route->dev, hdr->dest, daddr_buf) == 0)
daddr = daddr_buf;
@@ -1032,6 +1042,7 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
tag = req_tag & MCTP_TAG_MASK;
}
skb->pkt_type = PACKET_OUTGOING;
skb->protocol = htons(ETH_P_MCTP);
skb->priority = 0;
skb_reset_transport_header(skb);