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net/sched: Add actions for MPLS L2 VPNs

PATCH In review Guillaume Nault 2 participants 4 messages Oct 2, 2020 – Oct 4, 2020

Subsystems (4)
Networking Network drivers Traffic control (tc) Openvswitch
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Guillaume Nault

author
#0 lore raw

cover net/sched: Add actions for MPLS L2 VPNs

This patch series adds the necessary TC actions for supporting layer 2 MPLS VPNs (VPLS).

The objective is to give the possibility to add an MPLS header right before an skb's mac header, then to prepend this MPLS packet with a new Ethernet header with the MAC address of the next hop.

Patch 1 implements the actions for adding and removing the external Ethernet header.
Patch 2 adds the possibility to push an MPLS header before the mac header.

Most of the code already exists as these operations were first implemented in openvswitch.

Practical example, with encap on Host-A and decap on Host-B:

Host-A# tc filter add dev ethAx ingress matchall \

           action mpls mac_push label 20                  \
           action vlan push_eth dst_mac 02:00:00:00:00:02 \
                                src_mac 02:00:00:00:00:01 \
           action mirred egress redirect dev ethAy

Host-B# tc filter add dev ethBx ingress protocol mpls_uc \

           flower mpls_label 20 mpls_bos 1                \
           action vlan pop_eth                            \
           action mpls pop proto teb                      \

action mirred egress redirect dev ethBy

Guillaume Nault (2):
net/sched: act_vlan: Add {POP,PUSH}_ETH actions net/sched: act_mpls: Add action to push MPLS LSE before Ethernet
header

 include/linux/skbuff.h              |  3 ++
 include/net/tc_act/tc_vlan.h        |  2 +
 include/uapi/linux/tc_act/tc_mpls.h |  1 +
 include/uapi/linux/tc_act/tc_vlan.h |  4 ++
 net/core/skbuff.c                   | 67 +++++++++++++++++++++++++++++
 net/openvswitch/actions.c           | 28 +++++-------
 net/sched/act_mpls.c                | 18 ++++++++
 net/sched/act_vlan.c                | 40 +++++++++++++++++
 8 files changed, 145 insertions(+), 18 deletions(-)
Signature · 1 line
2.21.3
author
#1 lore raw

PATCH 1/2 net/sched: act_vlan: Add {POP,PUSH}_ETH actions

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 <[email protected]>
---
 include/linux/skbuff.h              |  3 ++
 include/net/tc_act/tc_vlan.h        |  2 +
 include/uapi/linux/tc_act/tc_vlan.h |  4 ++
 net/core/skbuff.c                   | 67 +++++++++++++++++++++++++++++
 net/openvswitch/actions.c           | 28 +++++-------
 net/sched/act_vlan.c                | 40 +++++++++++++++++
 6 files changed, 126 insertions(+), 18 deletions(-)
include/linux/skbuff.h +3 -0
index 3d0cf3722bb4..42131e325e27 100644
@@ -3573,6 +3573,9 @@ 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_eth_pop(struct sk_buff *skb);
+int skb_eth_push(struct sk_buff *skb, const unsigned char *dst,
+		 const unsigned char *src);
 int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
 		  int mac_len, bool ethernet);
 int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
include/net/tc_act/tc_vlan.h +2 -0
index 4e2502408c31..f051046ba034 100644
@@ -11,6 +11,8 @@
 
 struct tcf_vlan_params {
 	int               tcfv_action;
+	unsigned char     tcfv_push_dst[ETH_ALEN];
+	unsigned char     tcfv_push_src[ETH_ALEN];
 	u16               tcfv_push_vid;
 	__be16            tcfv_push_proto;
 	u8                tcfv_push_prio;
include/uapi/linux/tc_act/tc_vlan.h +4 -0
index 168995b54a70..5b306fe815cc 100644
@@ -16,6 +16,8 @@
 #define TCA_VLAN_ACT_POP	1
 #define TCA_VLAN_ACT_PUSH	2
 #define TCA_VLAN_ACT_MODIFY	3
+#define TCA_VLAN_ACT_POP_ETH	4
+#define TCA_VLAN_ACT_PUSH_ETH	5
 
 struct tc_vlan {
 	tc_gen;

@@ -30,6 +32,8 @@ enum {
 	TCA_VLAN_PUSH_VLAN_PROTOCOL,
 	TCA_VLAN_PAD,
 	TCA_VLAN_PUSH_VLAN_PRIORITY,
+	TCA_VLAN_PUSH_ETH_DST,
+	TCA_VLAN_PUSH_ETH_SRC,
 	__TCA_VLAN_MAX,
 };
 #define TCA_VLAN_MAX (__TCA_VLAN_MAX - 1)
net/core/skbuff.c +67 -0

73 lines not on this page · raw message

net/openvswitch/actions.c +10 -18
index 855f2c155956..b87bfc82f44f 100644
@@ -277,9 +277,11 @@ static int set_eth_addr(struct sk_buff *skb, struct sw_flow_key *flow_key,
  */
 static int pop_eth(struct sk_buff *skb, struct sw_flow_key *key)
 {
-	skb_pull_rcsum(skb, ETH_HLEN);
-	skb_reset_mac_header(skb);
-	skb_reset_mac_len(skb);
+	int err;
+
+	err = skb_eth_pop(skb);
+	if (err)
+		return err;
 
 	/* safe right before invalidate_flow_key */
 	key->mac_proto = MAC_PROTO_NONE;

@@ -290,22 +292,12 @@ static int pop_eth(struct sk_buff *skb, struct sw_flow_key *key)
 static int push_eth(struct sk_buff *skb, struct sw_flow_key *key,
 		    const struct ovs_action_push_eth *ethh)
 {
-	struct ethhdr *hdr;
-
-	/* Add the new Ethernet header */
-	if (skb_cow_head(skb, ETH_HLEN) < 0)
-		return -ENOMEM;
-
-	skb_push(skb, ETH_HLEN);
-	skb_reset_mac_header(skb);
-	skb_reset_mac_len(skb);
-
-	hdr = eth_hdr(skb);
-	ether_addr_copy(hdr->h_source, ethh->addresses.eth_src);
-	ether_addr_copy(hdr->h_dest, ethh->addresses.eth_dst);
-	hdr->h_proto = skb->protocol;
+	int err;
 
-	skb_postpush_rcsum(skb, hdr, ETH_HLEN);
+	err = skb_eth_push(skb, ethh->addresses.eth_dst,
+			   ethh->addresses.eth_src);
+	if (err)
+		return err;
 
 	/* safe right before invalidate_flow_key */
 	key->mac_proto = MAC_PROTO_ETHERNET;
net/sched/act_vlan.c +40 -0
index a5ff9f68ab02..8758bd2a78fa 100644
@@ -77,6 +77,16 @@ static int tcf_vlan_act(struct sk_buff *skb, const struct tc_action *a,
 		/* put updated tci as hwaccel tag */
 		__vlan_hwaccel_put_tag(skb, p->tcfv_push_proto, tci);
 		break;
+	case TCA_VLAN_ACT_POP_ETH:
+		err = skb_eth_pop(skb);
+		if (err)
+			goto drop;
+		break;
+	case TCA_VLAN_ACT_PUSH_ETH:
+		err = skb_eth_push(skb, p->tcfv_push_dst, p->tcfv_push_src);
+		if (err)
+			goto drop;
+		break;
 	default:
 		BUG();
 	}

@@ -93,10 +103,13 @@ static int tcf_vlan_act(struct sk_buff *skb, const struct tc_action *a,
 }
 
 static const struct nla_policy vlan_policy[TCA_VLAN_MAX + 1] = {
+	[TCA_VLAN_UNSPEC]		= { .strict_start_type = TCA_VLAN_PUSH_ETH_DST },
 	[TCA_VLAN_PARMS]		= { .len = sizeof(struct tc_vlan) },
 	[TCA_VLAN_PUSH_VLAN_ID]		= { .type = NLA_U16 },
 	[TCA_VLAN_PUSH_VLAN_PROTOCOL]	= { .type = NLA_U16 },
 	[TCA_VLAN_PUSH_VLAN_PRIORITY]	= { .type = NLA_U8 },
+	[TCA_VLAN_PUSH_ETH_DST]		= NLA_POLICY_ETH_ADDR,
+	[TCA_VLAN_PUSH_ETH_SRC]		= NLA_POLICY_ETH_ADDR,
 };
 
 static int tcf_vlan_init(struct net *net, struct nlattr *nla,

@@ -179,6 +192,17 @@ static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 		if (tb[TCA_VLAN_PUSH_VLAN_PRIORITY])
 			push_prio = nla_get_u8(tb[TCA_VLAN_PUSH_VLAN_PRIORITY]);
 		break;
+	case TCA_VLAN_ACT_POP_ETH:
+		break;
+	case TCA_VLAN_ACT_PUSH_ETH:
+		if (!tb[TCA_VLAN_PUSH_ETH_DST] || !tb[TCA_VLAN_PUSH_ETH_SRC]) {
+			if (exists)
+				tcf_idr_release(*a, bind);
+			else
+				tcf_idr_cleanup(tn, index);
+			return -EINVAL;
+		}
+		break;
 	default:
 		if (exists)
 			tcf_idr_release(*a, bind);

@@ -219,6 +243,13 @@ static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 	p->tcfv_push_prio = push_prio;
 	p->tcfv_push_proto = push_proto;
 
+	if (action == TCA_VLAN_ACT_PUSH_ETH) {
+		nla_memcpy(&p->tcfv_push_dst, tb[TCA_VLAN_PUSH_ETH_DST],
+			   ETH_ALEN);
+		nla_memcpy(&p->tcfv_push_src, tb[TCA_VLAN_PUSH_ETH_SRC],
+			   ETH_ALEN);
+	}
+
 	spin_lock_bh(&v->tcf_lock);
 	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 	p = rcu_replace_pointer(v->vlan_p, p, lockdep_is_held(&v->tcf_lock));

@@ -279,6 +310,15 @@ static int tcf_vlan_dump(struct sk_buff *skb, struct tc_action *a,
 					      p->tcfv_push_prio))))
 		goto nla_put_failure;
 
+	if (p->tcfv_action == TCA_VLAN_ACT_PUSH_ETH) {
+		if (nla_put(skb, TCA_VLAN_PUSH_ETH_DST, ETH_ALEN,
+			    p->tcfv_push_dst))
+			goto nla_put_failure;
+		if (nla_put(skb, TCA_VLAN_PUSH_ETH_SRC, ETH_ALEN,
+			    p->tcfv_push_src))
+			goto nla_put_failure;
+	}
+
 	tcf_tm_dump(&t, &v->tcf_tm);
 	if (nla_put_64bit(skb, TCA_VLAN_TM, sizeof(t), &t, TCA_VLAN_PAD))
 		goto nla_put_failure;
Signature · 1 line
2.21.3
author
#2 lore raw

PATCH 2/2 net/sched: act_mpls: Add action to push MPLS LSE before Ethernet header

In reply to Guillaume Nault

Define the MAC_PUSH action which pushes an MPLS LSE before the mac header (instead of between the mac and the network headers as the plain PUSH action does).

The only special case is when the skb has an offloaded VLAN. In that case, it has to be inlined before pushing the MPLS header.

Signed-off-by Guillaume Nault <[email protected]>
---
 include/uapi/linux/tc_act/tc_mpls.h |  1 +
 net/sched/act_mpls.c                | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)
include/uapi/linux/tc_act/tc_mpls.h +1 -0
index 9360e95273c7..9e4e8f52a779 100644
@@ -10,6 +10,7 @@
 #define TCA_MPLS_ACT_PUSH	2
 #define TCA_MPLS_ACT_MODIFY	3
 #define TCA_MPLS_ACT_DEC_TTL	4
+#define TCA_MPLS_ACT_MAC_PUSH	5
 
 struct tc_mpls {
 	tc_gen;		/* generic TC action fields. */
net/sched/act_mpls.c +18 -0
index 8118e2640979..bb6b715636db 100644
@@ -87,6 +87,23 @@ static int tcf_mpls_act(struct sk_buff *skb, const struct tc_action *a,
 				  skb->dev && skb->dev->type == ARPHRD_ETHER))
 			goto drop;
 		break;
+	case TCA_MPLS_ACT_MAC_PUSH:
+		if (skb_vlan_tag_present(skb)) {
+			if (__vlan_insert_inner_tag(skb, skb->vlan_proto,
+						    skb_vlan_tag_get(skb),
+						    ETH_HLEN) < 0)
+				goto drop;
+
+			skb->protocol = skb->vlan_proto;
+			__vlan_hwaccel_clear_tag(skb);
+		}
+
+		new_lse = tcf_mpls_get_lse(NULL, p, mac_len ||
+					   !eth_p_mpls(skb->protocol));
+
+		if (skb_mpls_push(skb, new_lse, p->tcfm_proto, 0, false))
+			goto drop;
+		break;
 	case TCA_MPLS_ACT_MODIFY:
 		new_lse = tcf_mpls_get_lse(mpls_hdr(skb), p, false);
 		if (skb_mpls_update_lse(skb, new_lse))

@@ -188,6 +205,7 @@ static int tcf_mpls_init(struct net *net, struct nlattr *nla,
 		}
 		break;
 	case TCA_MPLS_ACT_PUSH:
+	case TCA_MPLS_ACT_MAC_PUSH:
 		if (!tb[TCA_MPLS_LABEL]) {
 			NL_SET_ERR_MSG_MOD(extack, "Label is required for MPLS push");
 			return -EINVAL;
Signature · 1 line
2.21.3