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net/sched: act_vlan: Add {POP,PUSH}_ETH actions

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Implement TCA_VLAN_ACT_POP_ETH and TCA_VLAN_ACT_PUSH_ETH, to
respectively pop and push a base Ethernet header at the beginning of a
frame.

POP_ETH is just a matter of pulling ETH_HLEN bytes. VLAN tags, if any,
must be stripped before calling POP_ETH.

PUSH_ETH is restricted to skbs with no mac_header, and only the MAC
addresses can be configured. The Ethertype is automatically set from
skb->protocol. These restrictions ensure that all skb's fields remain
consistent, so that this action can't confuse other part of the
networking stack (like GSO).

Since openvswitch already had these actions, consolidate the code in
skbuff.c (like for vlan and mpls push/pop).

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Guillaume Nault
2020-10-03 00:44:28 +02:00
committed by David S. Miller
parent e275d49a69
commit 19fbcb36a3
6 changed files with 126 additions and 18 deletions
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67
net/core/skbuff.c
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@@ -5558,6 +5558,73 @@ int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
}
EXPORT_SYMBOL(skb_vlan_push);
/**
* skb_eth_pop() - Drop the Ethernet header at the head of a packet
*
* @skb: Socket buffer to modify
*
* Drop the Ethernet header of @skb.
*
* Expects that skb->data points to the mac header and that no VLAN tags are
* present.
*
* Returns 0 on success, -errno otherwise.
*/
int skb_eth_pop(struct sk_buff *skb)
{
if (!pskb_may_pull(skb, ETH_HLEN) || skb_vlan_tagged(skb) ||
skb_network_offset(skb) < ETH_HLEN)
return -EPROTO;
skb_pull_rcsum(skb, ETH_HLEN);
skb_reset_mac_header(skb);
skb_reset_mac_len(skb);
return 0;
}
EXPORT_SYMBOL(skb_eth_pop);
/**
* skb_eth_push() - Add a new Ethernet header at the head of a packet
*
* @skb: Socket buffer to modify
* @dst: Destination MAC address of the new header
* @src: Source MAC address of the new header
*
* Prepend @skb with a new Ethernet header.
*
* Expects that skb->data points to the mac header, which must be empty.
*
* Returns 0 on success, -errno otherwise.
*/
int skb_eth_push(struct sk_buff *skb, const unsigned char *dst,
const unsigned char *src)
{
struct ethhdr *eth;
int err;
if (skb_network_offset(skb) || skb_vlan_tag_present(skb))
return -EPROTO;
err = skb_cow_head(skb, sizeof(*eth));
if (err < 0)
return err;
skb_push(skb, sizeof(*eth));
skb_reset_mac_header(skb);
skb_reset_mac_len(skb);
eth = eth_hdr(skb);
ether_addr_copy(eth->h_dest, dst);
ether_addr_copy(eth->h_source, src);
eth->h_proto = skb->protocol;
skb_postpush_rcsum(skb, eth, sizeof(*eth));
return 0;
}
EXPORT_SYMBOL(skb_eth_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)