[ovs-dev] [PATCH 1/5] datapath: Add basic MPLS support to kernel

Simon Horman horms at verge.net.au
Fri Oct 5 08:05:52 UTC 2012


From: Leo Alterman <lalterman at nicira.com>

Allow datapath to recognize and extract MPLS labels into flow keys
and execute actions which push, pop, and set labels on packets.

Signed-off-by: Leo Alterman <lalterman at nicira.com>
---
 datapath/actions.c          |   81 +++++++++++++++++++++++++++++++++++++++++++
 datapath/datapath.c         |   56 ++++++++++++++++++++++++++++++
 datapath/datapath.h         |    8 +++++
 datapath/flow.c             |   30 ++++++++++++++++
 datapath/flow.h             |    7 ++++
 datapath/vport.c            |    2 ++
 include/linux/openvswitch.h |   32 +++++++++++++++++
 7 files changed, 216 insertions(+)

diff --git a/datapath/actions.c b/datapath/actions.c
index ec9b595..c1d1a7f 100644
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -47,6 +47,67 @@ static int make_writable(struct sk_buff *skb, int write_len)
 	return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
 }
 
+static __be16 get_ethertype(const struct sk_buff *skb)
+{
+	struct ethhdr *hdr = (struct ethhdr *)(skb_cb_mpls_stack(skb) - ETH_HLEN);
+	return hdr->h_proto;
+}
+
+static void set_ethertype(struct sk_buff *skb, const __be16 ethertype)
+{
+	struct ethhdr *hdr = (struct ethhdr *)(skb_cb_mpls_stack(skb) - ETH_HLEN);
+	hdr->h_proto = ethertype;
+}
+
+static int push_mpls(struct sk_buff *skb, const struct ovs_action_push_mpls *mpls)
+{
+	u32 l2_size;
+	__be32 *new_mpls_label;
+
+	if (skb_cow_head(skb, MPLS_HLEN) < 0) {
+		kfree_skb(skb);
+		return -ENOMEM;
+	}
+
+	l2_size = skb_cb_mpls_stack_offset(skb);
+	skb_push(skb, MPLS_HLEN);
+	memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb), l2_size);
+	skb_reset_mac_header(skb);
+
+	new_mpls_label = (__be32 *)(skb_mac_header(skb) + l2_size);
+	*new_mpls_label = mpls->mpls_label;
+
+	set_ethertype(skb, mpls->mpls_ethertype);
+	return 0;
+}
+
+static int pop_mpls(struct sk_buff *skb, const __be16 *ethertype)
+{
+	__be16 current_ethertype = get_ethertype(skb);
+	if (current_ethertype == htons(ETH_P_MPLS_UC) ||
+		current_ethertype == htons(ETH_P_MPLS_MC)) {
+		u32 l2_size = skb_cb_mpls_stack_offset(skb);
+
+		memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb), l2_size);
+
+		skb_pull(skb, MPLS_HLEN);
+		skb_reset_mac_header(skb);
+
+		set_ethertype(skb, *ethertype);
+	}
+	return 0;
+}
+
+static int set_mpls(struct sk_buff *skb, const __be32 *mpls_label)
+{
+	__be16 current_ethertype = get_ethertype(skb);
+	if (current_ethertype == htons(ETH_P_MPLS_UC) ||
+		current_ethertype == htons(ETH_P_MPLS_MC)) {
+		memcpy(skb_cb_mpls_stack(skb), mpls_label, sizeof(__be32));
+	}
+	return 0;
+}
+
 /* remove VLAN header from packet and update csum accordingly. */
 static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
 {
@@ -100,6 +161,9 @@ static int pop_vlan(struct sk_buff *skb)
 		return err;
 
 	__vlan_hwaccel_put_tag(skb, ntohs(tci));
+
+	/* update pointer to MPLS label stack */
+	skb_cb_set_mpls_stack(skb);
 	return 0;
 }
 
@@ -120,6 +184,9 @@ static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vla
 
 	}
 	__vlan_hwaccel_put_tag(skb, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
+
+	/* update pointer to MPLS label stack */
+	skb_cb_set_mpls_stack(skb);
 	return 0;
 }
 
@@ -396,6 +463,20 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 			output_userspace(dp, skb, a);
 			break;
 
+		case OVS_ACTION_ATTR_PUSH_MPLS:
+			err = push_mpls(skb, nla_data(a));
+			if (unlikely(err)) /* skb already freed. */
+				return err;
+			break;
+
+		case OVS_ACTION_ATTR_POP_MPLS:
+			err = pop_mpls(skb, nla_data(a));
+			break;
+
+		case OVS_ACTION_ATTR_SET_MPLS:
+			err = set_mpls(skb, nla_data(a));
+			break;
+
 		case OVS_ACTION_ATTR_PUSH_VLAN:
 			err = push_vlan(skb, nla_data(a));
 			if (unlikely(err)) /* skb already freed. */
diff --git a/datapath/datapath.c b/datapath/datapath.c
index a6915fb..79c50af 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -74,6 +74,41 @@ int ovs_net_id __read_mostly;
 int (*ovs_dp_ioctl_hook)(struct net_device *dev, struct ifreq *rq, int cmd);
 EXPORT_SYMBOL(ovs_dp_ioctl_hook);
 
+void skb_cb_set_mpls_stack(struct sk_buff *skb)
+{
+	struct ethhdr *eth;
+	int nh_ofs;
+	__be16 dl_type = 0;
+
+	eth = eth_hdr(skb);
+	nh_ofs = sizeof(struct ethhdr);
+	if (likely(eth->h_proto >= htons(ETH_TYPE_MIN))) {
+		dl_type = eth->h_proto;
+
+		while (dl_type == htons(ETH_P_8021Q) &&
+				skb->len >= nh_ofs + sizeof(struct vlan_hdr)) {
+			struct vlan_hdr *vh = (struct vlan_hdr*)(skb->data + nh_ofs);
+			dl_type = vh->h_vlan_encapsulated_proto;
+			nh_ofs += sizeof(struct vlan_hdr);
+		}
+
+		OVS_CB(skb)->mpls_stack = nh_ofs;
+	} else {
+		OVS_CB(skb)->mpls_stack = 0;
+	}
+}
+
+unsigned char *skb_cb_mpls_stack(const struct sk_buff *skb)
+{
+	return OVS_CB(skb)->mpls_stack ?
+					skb_mac_header(skb) + OVS_CB(skb)->mpls_stack : 0;
+}
+
+ptrdiff_t skb_cb_mpls_stack_offset(const struct sk_buff *skb)
+{
+	return OVS_CB(skb)->mpls_stack;
+}
+
 /**
  * DOC: Locking:
  *
@@ -663,12 +698,17 @@ static int validate_actions(const struct nlattr *attr,
 		static const u32 action_lens[OVS_ACTION_ATTR_MAX + 1] = {
 			[OVS_ACTION_ATTR_OUTPUT] = sizeof(u32),
 			[OVS_ACTION_ATTR_USERSPACE] = (u32)-1,
+			[OVS_ACTION_ATTR_PUSH_MPLS] = sizeof(struct ovs_action_push_mpls),
+			[OVS_ACTION_ATTR_POP_MPLS] = sizeof(__be16),
+			[OVS_ACTION_ATTR_SET_MPLS] = sizeof(__be32),
 			[OVS_ACTION_ATTR_PUSH_VLAN] = sizeof(struct ovs_action_push_vlan),
 			[OVS_ACTION_ATTR_POP_VLAN] = 0,
 			[OVS_ACTION_ATTR_SET] = (u32)-1,
 			[OVS_ACTION_ATTR_SAMPLE] = (u32)-1
 		};
 		const struct ovs_action_push_vlan *vlan;
+		__be16 mpls_ethertype;
+		__be32 mpls_label;
 		int type = nla_type(a);
 
 		if (type > OVS_ACTION_ATTR_MAX ||
@@ -691,6 +731,22 @@ static int validate_actions(const struct nlattr *attr,
 				return -EINVAL;
 			break;
 
+		case OVS_ACTION_ATTR_PUSH_MPLS:
+			mpls_ethertype = nla_get_be16(a);
+			if (mpls_ethertype != htons(ETH_P_MPLS_UC) &&
+				mpls_ethertype != htons(ETH_P_MPLS_MC))
+				return -EINVAL;
+			break;
+
+		case OVS_ACTION_ATTR_POP_MPLS:
+			break;
+
+		case OVS_ACTION_ATTR_SET_MPLS:
+			mpls_label = nla_get_be32(a);
+			if (mpls_label == htonl(0)) {
+				return -EINVAL;
+			}
+			break;
 
 		case OVS_ACTION_ATTR_POP_VLAN:
 			break;
diff --git a/datapath/datapath.h b/datapath/datapath.h
index affbf0e..1801ccd 100644
--- a/datapath/datapath.h
+++ b/datapath/datapath.h
@@ -97,6 +97,9 @@ struct datapath {
  * struct ovs_skb_cb - OVS data in skb CB
  * @flow: The flow associated with this packet.  May be %NULL if no flow.
  * @tun_id: ID of the tunnel that encapsulated this packet.  It is 0 if the
+ * packet is not being tunneled.
+ * @mpls_stack: Offset of the packet's MPLS stack from the beginning of the
+ * ethernet frame.  It is 0 if no MPLS stack is present.
  * @ip_summed: Consistently stores L4 checksumming status across different
  * kernel versions.
  * @csum_start: Stores the offset from which to start checksumming independent
@@ -108,6 +111,7 @@ struct datapath {
 struct ovs_skb_cb {
 	struct sw_flow		*flow;
 	__be64			tun_id;
+	ptrdiff_t	mpls_stack;
 #ifdef NEED_CSUM_NORMALIZE
 	enum csum_type		ip_summed;
 	u16			csum_start;
@@ -192,4 +196,8 @@ struct sk_buff *ovs_vport_cmd_build_info(struct vport *, u32 pid, u32 seq,
 					 u8 cmd);
 
 int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb);
+
+void skb_cb_set_mpls_stack(struct sk_buff *skb);
+unsigned char *skb_cb_mpls_stack(const struct sk_buff *skb);
+ptrdiff_t skb_cb_mpls_stack_offset(const struct sk_buff *skb);
 #endif /* datapath.h */
diff --git a/datapath/flow.c b/datapath/flow.c
index d07337c..40df8ff 100644
--- a/datapath/flow.c
+++ b/datapath/flow.c
@@ -739,6 +739,14 @@ int ovs_flow_extract(struct sk_buff *skb, u16 in_port, struct sw_flow_key *key,
 				key_len = SW_FLOW_KEY_OFFSET(ipv4.arp);
 			}
 		}
+	} else if (key->eth.type == htons(ETH_P_MPLS_UC) ||
+				key->eth.type == htons(ETH_P_MPLS_MC)) {
+		error = check_header(skb, MPLS_HLEN);
+		if (unlikely(error))
+			goto out;
+
+		key_len = SW_FLOW_KEY_OFFSET(mpls.top_label);
+		memcpy(&key->mpls.top_label, skb_network_header(skb), MPLS_HLEN);
 	} else if (key->eth.type == htons(ETH_P_IPV6)) {
 		int nh_len;             /* IPv6 Header + Extensions */
 
@@ -836,6 +844,7 @@ const int ovs_key_lens[OVS_KEY_ATTR_MAX + 1] = {
 	[OVS_KEY_ATTR_ETHERNET] = sizeof(struct ovs_key_ethernet),
 	[OVS_KEY_ATTR_VLAN] = sizeof(__be16),
 	[OVS_KEY_ATTR_ETHERTYPE] = sizeof(__be16),
+	[OVS_KEY_ATTR_MPLS] = sizeof(struct ovs_key_mpls),
 	[OVS_KEY_ATTR_IPV4] = sizeof(struct ovs_key_ipv4),
 	[OVS_KEY_ATTR_IPV6] = sizeof(struct ovs_key_ipv6),
 	[OVS_KEY_ATTR_TCP] = sizeof(struct ovs_key_tcp),
@@ -1141,6 +1150,17 @@ int ovs_flow_from_nlattrs(struct sw_flow_key *swkey, int *key_lenp,
 		swkey->ip.proto = ntohs(arp_key->arp_op);
 		memcpy(swkey->ipv4.arp.sha, arp_key->arp_sha, ETH_ALEN);
 		memcpy(swkey->ipv4.arp.tha, arp_key->arp_tha, ETH_ALEN);
+	} else if (swkey->eth.type == htons(ETH_P_MPLS_UC) || 
+				swkey->eth.type == htons(ETH_P_MPLS_MC)) {
+		const struct ovs_key_mpls *mpls_key;
+
+		if (!(attrs & (1 << OVS_KEY_ATTR_MPLS)))
+			return -EINVAL;
+		attrs &= ~(1 << OVS_KEY_ATTR_MPLS);
+
+		key_len = SW_FLOW_KEY_OFFSET(mpls.top_label);
+		mpls_key = nla_data(a[OVS_KEY_ATTR_MPLS]);
+		swkey->mpls.top_label = mpls_key->mpls_top_label;
 	}
 
 	if (attrs)
@@ -1284,6 +1304,16 @@ int ovs_flow_to_nlattrs(const struct sw_flow_key *swkey, struct sk_buff *skb)
 		arp_key->arp_op = htons(swkey->ip.proto);
 		memcpy(arp_key->arp_sha, swkey->ipv4.arp.sha, ETH_ALEN);
 		memcpy(arp_key->arp_tha, swkey->ipv4.arp.tha, ETH_ALEN);
+	} else if (swkey->eth.type == htons(ETH_P_MPLS_UC) || 
+				swkey->eth.type == htons(ETH_P_MPLS_MC)) {
+		struct ovs_key_mpls *mpls_key;
+
+		nla = nla_reserve(skb, OVS_KEY_ATTR_MPLS, sizeof(*mpls_key));
+		if (!nla)
+			goto nla_put_failure;
+		mpls_key = nla_data(nla);
+		memset(mpls_key, 0, sizeof(struct ovs_key_mpls));
+		mpls_key->mpls_top_label = swkey->mpls.top_label;
 	}
 
 	if ((swkey->eth.type == htons(ETH_P_IP) ||
diff --git a/datapath/flow.h b/datapath/flow.h
index 02c563a..eb3fe49 100644
--- a/datapath/flow.h
+++ b/datapath/flow.h
@@ -53,6 +53,9 @@ struct sw_flow_key {
 		__be16 type;		/* Ethernet frame type. */
 	} eth;
 	struct {
+		__be32 top_label;	/* 0 if no MPLS, top label from stack otherwise */
+	} mpls;
+	struct {
 		u8     proto;		/* IP protocol or lower 8 bits of ARP opcode. */
 		u8     tos;		/* IP ToS. */
 		u8     ttl;		/* IP TTL/hop limit. */
@@ -126,6 +129,10 @@ struct arp_eth_header {
 	unsigned char       ar_tip[4];		/* target IP address        */
 } __packed;
 
+#define ETH_TYPE_MIN 0x600
+
+#define MPLS_HLEN 4
+
 int ovs_flow_init(void);
 void ovs_flow_exit(void);
 
diff --git a/datapath/vport.c b/datapath/vport.c
index dc7adfa..0ae4801 100644
--- a/datapath/vport.c
+++ b/datapath/vport.c
@@ -464,6 +464,8 @@ void ovs_vport_receive(struct vport *vport, struct sk_buff *skb)
 	if (!(vport->ops->flags & VPORT_F_TUN_ID))
 		OVS_CB(skb)->tun_id = 0;
 
+	skb_cb_set_mpls_stack(skb);
+
 	ovs_dp_process_received_packet(vport, skb);
 }
 
diff --git a/include/linux/openvswitch.h b/include/linux/openvswitch.h
index f5c9cca..78960d1 100644
--- a/include/linux/openvswitch.h
+++ b/include/linux/openvswitch.h
@@ -278,6 +278,7 @@ enum ovs_key_attr {
 	OVS_KEY_ATTR_ICMPV6,    /* struct ovs_key_icmpv6 */
 	OVS_KEY_ATTR_ARP,       /* struct ovs_key_arp */
 	OVS_KEY_ATTR_ND,        /* struct ovs_key_nd */
+	OVS_KEY_ATTR_MPLS,      /* struct ovs_key_mpls */
 	OVS_KEY_ATTR_TUN_ID = 63, /* be64 tunnel ID */
 	__OVS_KEY_ATTR_MAX
 };
@@ -307,6 +308,10 @@ struct ovs_key_ethernet {
 	__u8	 eth_dst[6];
 };
 
+struct ovs_key_mpls {
+	__be32 mpls_top_label;
+};
+
 struct ovs_key_ipv4 {
 	__be32 ipv4_src;
 	__be32 ipv4_dst;
@@ -437,6 +442,20 @@ enum ovs_userspace_attr {
 #define OVS_USERSPACE_ATTR_MAX (__OVS_USERSPACE_ATTR_MAX - 1)
 
 /**
+ * struct ovs_action_push_mpls - %OVS_ACTION_ATTR_PUSH_MPLS action argument.
+ * @mpls_label: MPLS label to push.
+ * @mpls_ethertype: Ethertype to set in the encapsulating ethernet frame.
+ *
+ * The only values @mpls_ethertype should ever be given are %ETH_P_MPLS_UC and
+ * %ETH_P_MPLS_MC, indicating MPLS unicast or multicast. Any other values would
+ * produce a corrupt packet.
+ */
+struct ovs_action_push_mpls {
+	__be32 mpls_label;
+	__be16 mpls_ethertype; /* Either %ETH_P_MPLS_UC or %ETH_P_MPLS_MC */ 
+};
+
+/**
  * struct ovs_action_push_vlan - %OVS_ACTION_ATTR_PUSH_VLAN action argument.
  * @vlan_tpid: Tag protocol identifier (TPID) to push.
  * @vlan_tci: Tag control identifier (TCI) to push.  The CFI bit must be set
@@ -461,6 +480,16 @@ struct ovs_action_push_vlan {
  * @OVS_ACTION_ATTR_SET: Replaces the contents of an existing header.  The
  * single nested %OVS_KEY_ATTR_* attribute specifies a header to modify and its
  * value.
+ * @OVS_ACTION_ATTR_PUSH_MPLS: Push a new MPLS label onto the top of the packet
+ * MPLS stack. Set the ethertype of the encapsulating frame to either
+ * %ETH_P_MPLS_UC or %ETH_P_MPLS_MC to indicate the new packet contents.
+ * @OVS_ACTION_ATTR_POP_MPLS: Pop an MPLS label off of the packet's MPLS stack.
+ * Set the encapsulating frame's ethertype to indicate the new packet contents
+ * (this could potentially still be %ETH_P_MPLS_* if there are remaining MPLS
+ * labels).  If there are no MPLS labels as determined by ethertype, no action
+ * is taken.
+ * @OVS_ACTION_ATTR_SET_MPLS: Set the value of the top-most label in the MPLS
+ * label stack.  If there are no MPLS labels in the packet, no action is taken.
  * @OVS_ACTION_ATTR_PUSH_VLAN: Push a new outermost 802.1Q header onto the
  * packet.
  * @OVS_ACTION_ATTR_POP_VLAN: Pop the outermost 802.1Q header off the packet.
@@ -477,6 +506,9 @@ enum ovs_action_attr {
 	OVS_ACTION_ATTR_OUTPUT,	      /* u32 port number. */
 	OVS_ACTION_ATTR_USERSPACE,    /* Nested OVS_USERSPACE_ATTR_*. */
 	OVS_ACTION_ATTR_SET,          /* One nested OVS_KEY_ATTR_*. */
+	OVS_ACTION_ATTR_PUSH_MPLS,    /* struct ovs_action_push_mpls. */
+	OVS_ACTION_ATTR_POP_MPLS,     /* __be16 ethertype. */
+	OVS_ACTION_ATTR_SET_MPLS,     /* __be32 MPLS label */
 	OVS_ACTION_ATTR_PUSH_VLAN,    /* struct ovs_action_push_vlan. */
 	OVS_ACTION_ATTR_POP_VLAN,     /* No argument. */
 	OVS_ACTION_ATTR_SAMPLE,       /* Nested OVS_SAMPLE_ATTR_*. */
-- 
1.7.10.4




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