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 --- net/mctp/route.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/net/mctp/route.c b/net/mctp/route.c index d9c8e5a5f9ce9aefbf16730c65a1f54caa5592b9..128ac46dda5eb882994960b8c0eb671007ad8583 100644 --- a/net/mctp/route.c +++ b/net/mctp/route.c @@ -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); -- 2.39.5