From d27cf5c59a12f66425df29cd81f61aa73ef14ac1 Mon Sep 17 00:00:00 2001 From: John Hurley Date: Sun, 7 Jul 2019 15:01:56 +0100 Subject: net: core: add MPLS update core helper and use in OvS Open vSwitch allows the updating of an existing MPLS header on a packet. In preparation for supporting similar functionality in TC, move this to a common skb helper function. Signed-off-by: John Hurley Reviewed-by: Jakub Kicinski Reviewed-by: Simon Horman Reviewed-by: Willem de Bruijn Acked-by: Cong Wang Signed-off-by: David S. Miller --- net/core/skbuff.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'net/core/skbuff.c') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 8c00be4d8919..93443a01ab39 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5531,6 +5531,39 @@ int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto) } EXPORT_SYMBOL_GPL(skb_mpls_pop); +/** + * skb_mpls_update_lse() - modify outermost MPLS header and update csum + * + * @skb: buffer + * @mpls_lse: new MPLS label stack entry to update to + * + * Expects skb->data at mac header. + * + * Returns 0 on success, -errno otherwise. + */ +int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse) +{ + int err; + + if (unlikely(!eth_p_mpls(skb->protocol))) + return -EINVAL; + + err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN); + if (unlikely(err)) + return err; + + if (skb->ip_summed == CHECKSUM_COMPLETE) { + __be32 diff[] = { ~mpls_hdr(skb)->label_stack_entry, mpls_lse }; + + skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum); + } + + mpls_hdr(skb)->label_stack_entry = mpls_lse; + + return 0; +} +EXPORT_SYMBOL_GPL(skb_mpls_update_lse); + /** * alloc_skb_with_frags - allocate skb with page frags * -- cgit v1.2.3