net: core: move push MPLS functionality from OvS to core helper

Open vSwitch provides code to push an MPLS header to a packet. In
preparation for supporting this in TC, move the push code to an skb helper
that can be reused.

Signed-off-by: John Hurley <john.hurley@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 1fdfdbb..1dc5500 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3447,6 +3447,7 @@ int skb_ensure_writable(struct sk_buff *skb, int write_len);
 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci);
 int skb_vlan_pop(struct sk_buff *skb);
 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
+int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto);
 struct sk_buff *pskb_extract(struct sk_buff *skb, int off, int to_copy,
                             gfp_t gfp);
 

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index cdb0ccd..495fd74 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -66,6 +66,7 @@
 #include <net/checksum.h>
 #include <net/ip6_checksum.h>
 #include <net/xfrm.h>
+#include <net/mpls.h>
 
 #include <linux/uaccess.h>
 #include <trace/events/skb.h>
@@ -5425,6 +5426,69 @@ int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
 }
 EXPORT_SYMBOL(skb_vlan_push);
 
+/* Update the ethertype of hdr and the skb csum value if required. */
+static void skb_mod_eth_type(struct sk_buff *skb, struct ethhdr *hdr,
+                            __be16 ethertype)
+{
+       if (skb->ip_summed == CHECKSUM_COMPLETE) {
+               __be16 diff[] = { ~hdr->h_proto, ethertype };
+
+               skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
+       }
+
+       hdr->h_proto = ethertype;
+}
+
+/**
+ * skb_mpls_push() - push a new MPLS header after the mac header
+ *
+ * @skb: buffer
+ * @mpls_lse: MPLS label stack entry to push
+ * @mpls_proto: ethertype of the new MPLS header (expects 0x8847 or 0x8848)
+ *
+ * Expects skb->data at mac header.
+ *
+ * Returns 0 on success, -errno otherwise.
+ */
+int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto)
+{
+       struct mpls_shim_hdr *lse;
+       int err;
+
+       if (unlikely(!eth_p_mpls(mpls_proto)))
+               return -EINVAL;
+
+       /* Networking stack does not allow simultaneous Tunnel and MPLS GSO. */
+       if (skb->encapsulation)
+               return -EINVAL;
+
+       err = skb_cow_head(skb, MPLS_HLEN);
+       if (unlikely(err))
+               return err;
+
+       if (!skb->inner_protocol) {
+               skb_set_inner_network_header(skb, skb->mac_len);
+               skb_set_inner_protocol(skb, skb->protocol);
+       }
+
+       skb_push(skb, MPLS_HLEN);
+       memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
+               skb->mac_len);
+       skb_reset_mac_header(skb);
+       skb_set_network_header(skb, skb->mac_len);
+
+       lse = mpls_hdr(skb);
+       lse->label_stack_entry = mpls_lse;
+       skb_postpush_rcsum(skb, lse, MPLS_HLEN);
+
+       if (skb->dev && skb->dev->type == ARPHRD_ETHER)
+               skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
+       skb->protocol = mpls_proto;
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(skb_mpls_push);
+
 /**
  * alloc_skb_with_frags - allocate skb with page frags
  *

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index bd13146..a9a6c9c 100644 (file)
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -175,34 +175,11 @@ static void update_ethertype(struct sk_buff *skb, struct ethhdr *hdr,
 static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
                     const struct ovs_action_push_mpls *mpls)
 {
-       struct mpls_shim_hdr *new_mpls_lse;
-
-       /* Networking stack do not allow simultaneous Tunnel and MPLS GSO. */
-       if (skb->encapsulation)
-               return -ENOTSUPP;
-
-       if (skb_cow_head(skb, MPLS_HLEN) < 0)
-               return -ENOMEM;
-
-       if (!skb->inner_protocol) {
-               skb_set_inner_network_header(skb, skb->mac_len);
-               skb_set_inner_protocol(skb, skb->protocol);
-       }
-
-       skb_push(skb, MPLS_HLEN);
-       memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
-               skb->mac_len);
-       skb_reset_mac_header(skb);
-       skb_set_network_header(skb, skb->mac_len);
-
-       new_mpls_lse = mpls_hdr(skb);
-       new_mpls_lse->label_stack_entry = mpls->mpls_lse;
-
-       skb_postpush_rcsum(skb, new_mpls_lse, MPLS_HLEN);
+       int err;
 
-       if (ovs_key_mac_proto(key) == MAC_PROTO_ETHERNET)
-               update_ethertype(skb, eth_hdr(skb), mpls->mpls_ethertype);
-       skb->protocol = mpls->mpls_ethertype;
+       err = skb_mpls_push(skb, mpls->mpls_lse, mpls->mpls_ethertype);
+       if (err)
+               return err;
 
        invalidate_flow_key(key);
        return 0;