Commit 94c59aab authored by Daniel Borkmann's avatar Daniel Borkmann
Browse files

Merge branch 'bpf-l2-encap' 



Alan Maguire says:

====================
Extend bpf_skb_adjust_room growth to mark inner MAC header so
that L2 encapsulation can be used for tc tunnels.

Patch #1 extends the existing test_tc_tunnel to support UDP
encapsulation; later we want to be able to test MPLS over UDP
and MPLS over GRE encapsulation.

Patch #2 adds the BPF_F_ADJ_ROOM_ENCAP_L2(len) macro, which
allows specification of inner mac length.  Other approaches were
explored prior to taking this approach.  Specifically, I tried
automatically computing the inner mac length on the basis of the
specified flags (so inner maclen for GRE/IPv4 encap is the len_diff
specified to bpf_skb_adjust_room minus GRE + IPv4 header length
for example).  Problem with this is that we don't know for sure
what form of GRE/UDP header we have; is it a full GRE header,
or is it a FOU UDP header or generic UDP encap header? My fear
here was we'd end up with an explosion of flags.  The other approach
tried was to support inner L2 header marking as a separate room
adjustment, i.e. adjust for L3/L4 encap, then call
bpf_skb_adjust_room for L2 encap.  This can be made to work but
because it imposed an order on operations, felt a bit clunky.

Patch #3 syncs tools/ bpf.h.

Patch #4 extends the tests again to support MPLSoverGRE,
MPLSoverUDP, and transparent ethernet bridging (TEB) where
the inner L2 header is an ethernet header.  Testing of BPF
encap against tunnels is done for cases where configuration
of such tunnels is possible (MPLSoverGRE[6], MPLSoverUDP,
gre[6]tap), and skipped otherwise.  Testing of BPF encap/decap
is always carried out.

Changes since v2:
 - updated tools/testing/selftest/bpf/config with FOU/MPLS CONFIG
   variables (patches 1, 4)
 - reduced noise in patch 1 by avoiding unnecessary movement of code
 - eliminated inner_mac variable in bpf_skb_net_grow (patch 2)

Changes since v1:
 - fixed formatting of commit references.
 - BPF_F_ADJ_ROOM_FIXED_GSO flag enabled on all variants (patch 1)
 - fixed fou6 options for UDP encap; checksum errors observed were
   due to the fact fou6 tunnel was not set up with correct ipproto
   options (41 -6).  0 checksums work fine (patch 1)
 - added definitions for mask and shift used in setting L2 length
   (patch 2)
 - allow udp encap with fixed GSO (patch 2)
 - changed "elen" to "l2_len" to be more descriptive (patch 4)
====================

Acked-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parents c695865c 3ec61df8

include/uapi/linux/bpf.h

+10 −0
Original line number Diff line number Diff line
@@ -1523,6 +1523,10 @@ union bpf_attr { 
 *		* **BPF_F_ADJ_ROOM_ENCAP_L4_UDP **:

 *		  Use with ENCAP_L3 flags to further specify the tunnel type.

 *

 *		* **BPF_F_ADJ_ROOM_ENCAP_L2(len) **:

 *		  Use with ENCAP_L3/L4 flags to further specify the tunnel

 *		  type; **len** is the length of the inner MAC header.

 *

 * 		A call to this helper is susceptible to change the underlaying

 * 		packet buffer. Therefore, at load time, all checks on pointers

 * 		previously done by the verifier are invalidated and must be
@@ -2664,10 +2668,16 @@ enum bpf_func_id { 
/* BPF_FUNC_skb_adjust_room flags. */

#define BPF_F_ADJ_ROOM_FIXED_GSO	(1ULL << 0)



#define	BPF_ADJ_ROOM_ENCAP_L2_MASK	0xff

#define	BPF_ADJ_ROOM_ENCAP_L2_SHIFT	56



#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV4	(1ULL << 1)

#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV6	(1ULL << 2)

#define BPF_F_ADJ_ROOM_ENCAP_L4_GRE	(1ULL << 3)

#define BPF_F_ADJ_ROOM_ENCAP_L4_UDP	(1ULL << 4)

#define	BPF_F_ADJ_ROOM_ENCAP_L2(len)	(((__u64)len & \

					  BPF_ADJ_ROOM_ENCAP_L2_MASK) \

					 << BPF_ADJ_ROOM_ENCAP_L2_SHIFT)



/* Mode for BPF_FUNC_skb_adjust_room helper. */

enum bpf_adj_room_mode {

net/core/filter.c

+8 −4
Original line number Diff line number Diff line
@@ -2969,11 +2969,14 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb) 
#define BPF_F_ADJ_ROOM_MASK		(BPF_F_ADJ_ROOM_FIXED_GSO | \

					 BPF_F_ADJ_ROOM_ENCAP_L3_MASK | \

					 BPF_F_ADJ_ROOM_ENCAP_L4_GRE | \

					 BPF_F_ADJ_ROOM_ENCAP_L4_UDP)

					 BPF_F_ADJ_ROOM_ENCAP_L4_UDP | \

					 BPF_F_ADJ_ROOM_ENCAP_L2( \

					  BPF_ADJ_ROOM_ENCAP_L2_MASK))



static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,

			    u64 flags)

{

	u8 inner_mac_len = flags >> BPF_ADJ_ROOM_ENCAP_L2_SHIFT;

	bool encap = flags & BPF_F_ADJ_ROOM_ENCAP_L3_MASK;

	u16 mac_len = 0, inner_net = 0, inner_trans = 0;

	unsigned int gso_type = SKB_GSO_DODGY;
@@ -3008,6 +3011,8 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff, 


		mac_len = skb->network_header - skb->mac_header;

		inner_net = skb->network_header;

		if (inner_mac_len > len_diff)

			return -EINVAL;

		inner_trans = skb->transport_header;

	}
@@ -3016,8 +3021,7 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff, 
		return ret;



	if (encap) {

		/* inner mac == inner_net on l3 encap */

		skb->inner_mac_header = inner_net;

		skb->inner_mac_header = inner_net - inner_mac_len;

		skb->inner_network_header = inner_net;

		skb->inner_transport_header = inner_trans;

		skb_set_inner_protocol(skb, skb->protocol);
@@ -3031,7 +3035,7 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff, 
			gso_type |= SKB_GSO_GRE;

		else if (flags & BPF_F_ADJ_ROOM_ENCAP_L3_IPV6)

			gso_type |= SKB_GSO_IPXIP6;

		else

		else if (flags & BPF_F_ADJ_ROOM_ENCAP_L3_IPV4)

			gso_type |= SKB_GSO_IPXIP4;



		if (flags & BPF_F_ADJ_ROOM_ENCAP_L4_GRE ||

tools/include/uapi/linux/bpf.h

+10 −0
Original line number Diff line number Diff line
@@ -1523,6 +1523,10 @@ union bpf_attr { 
 *		* **BPF_F_ADJ_ROOM_ENCAP_L4_UDP **:

 *		  Use with ENCAP_L3 flags to further specify the tunnel type.

 *

 *		* **BPF_F_ADJ_ROOM_ENCAP_L2(len) **:

 *		  Use with ENCAP_L3/L4 flags to further specify the tunnel

 *		  type; **len** is the length of the inner MAC header.

 *

 * 		A call to this helper is susceptible to change the underlaying

 * 		packet buffer. Therefore, at load time, all checks on pointers

 * 		previously done by the verifier are invalidated and must be
@@ -2664,10 +2668,16 @@ enum bpf_func_id { 
/* BPF_FUNC_skb_adjust_room flags. */

#define BPF_F_ADJ_ROOM_FIXED_GSO	(1ULL << 0)



#define	BPF_ADJ_ROOM_ENCAP_L2_MASK	0xff

#define	BPF_ADJ_ROOM_ENCAP_L2_SHIFT	56



#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV4	(1ULL << 1)

#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV6	(1ULL << 2)

#define BPF_F_ADJ_ROOM_ENCAP_L4_GRE	(1ULL << 3)

#define BPF_F_ADJ_ROOM_ENCAP_L4_UDP	(1ULL << 4)

#define	BPF_F_ADJ_ROOM_ENCAP_L2(len)	(((__u64)len & \

					  BPF_ADJ_ROOM_ENCAP_L2_MASK) \

					 << BPF_ADJ_ROOM_ENCAP_L2_SHIFT)



/* Mode for BPF_FUNC_skb_adjust_room helper. */

enum bpf_adj_room_mode {

tools/testing/selftests/bpf/config

+8 −0
Original line number Diff line number Diff line
@@ -25,3 +25,11 @@ CONFIG_XDP_SOCKETS=y 
CONFIG_FTRACE_SYSCALLS=y

CONFIG_IPV6_TUNNEL=y

CONFIG_IPV6_GRE=y

CONFIG_NET_FOU=m

CONFIG_NET_FOU_IP_TUNNELS=y

CONFIG_IPV6_FOU=m

CONFIG_IPV6_FOU_TUNNEL=m

CONFIG_MPLS=y

CONFIG_NET_MPLS_GSO=m

CONFIG_MPLS_ROUTING=m

CONFIG_MPLS_IPTUNNEL=m

tools/testing/selftests/bpf/progs/test_tc_tunnel.c

+270 −51
Original line number Diff line number Diff line
@@ -11,7 +11,9 @@ 
#include <linux/in.h>

#include <linux/ip.h>

#include <linux/ipv6.h>

#include <linux/mpls.h>

#include <linux/tcp.h>

#include <linux/udp.h>

#include <linux/pkt_cls.h>

#include <linux/types.h>
@@ -20,16 +22,36 @@ 


static const int cfg_port = 8000;



struct grev4hdr {

	struct iphdr ip;

static const int cfg_udp_src = 20000;



#define	UDP_PORT		5555

#define	MPLS_OVER_UDP_PORT	6635

#define	ETH_OVER_UDP_PORT	7777



/* MPLS label 1000 with S bit (last label) set and ttl of 255. */

static const __u32 mpls_label = __bpf_constant_htonl(1000 << 12 |

						     MPLS_LS_S_MASK | 0xff);



struct gre_hdr {

	__be16 flags;

	__be16 protocol;

} __attribute__((packed));



struct grev6hdr {

union l4hdr {

	struct udphdr udp;

	struct gre_hdr gre;

};



struct v4hdr {

	struct iphdr ip;

	union l4hdr l4hdr;

	__u8 pad[16];			/* enough space for L2 header */

} __attribute__((packed));



struct v6hdr {

	struct ipv6hdr ip;

	__be16 flags;

	__be16 protocol;

	union l4hdr l4hdr;

	__u8 pad[16];			/* enough space for L2 header */

} __attribute__((packed));



static __always_inline void set_ipv4_csum(struct iphdr *iph)
@@ -47,13 +69,15 @@ static __always_inline void set_ipv4_csum(struct iphdr *iph) 
	iph->check = ~((csum & 0xffff) + (csum >> 16));

}



static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)

static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,

				      __u16 l2_proto)

{

	struct grev4hdr h_outer;

	__u16 udp_dst = UDP_PORT;

	struct iphdr iph_inner;

	struct v4hdr h_outer;

	struct tcphdr tcph;

	int olen, l2_len;

	__u64 flags;

	int olen;



	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,

			       sizeof(iph_inner)) < 0)
@@ -70,14 +94,59 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre) 
	if (tcph.dest != __bpf_constant_htons(cfg_port))

		return TC_ACT_OK;



	olen = sizeof(h_outer.ip);

	l2_len = 0;



	flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV4;

	if (with_gre) {



	switch (l2_proto) {

	case ETH_P_MPLS_UC:

		l2_len = sizeof(mpls_label);

		udp_dst = MPLS_OVER_UDP_PORT;

		break;

	case ETH_P_TEB:

		l2_len = ETH_HLEN;

		udp_dst = ETH_OVER_UDP_PORT;

		break;

	}

	flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);



	switch (encap_proto) {

	case IPPROTO_GRE:

		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;

		olen = sizeof(h_outer);

	} else {

		olen = sizeof(h_outer.ip);

		olen += sizeof(h_outer.l4hdr.gre);

		h_outer.l4hdr.gre.protocol = bpf_htons(l2_proto);

		h_outer.l4hdr.gre.flags = 0;

		break;

	case IPPROTO_UDP:

		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_UDP;

		olen += sizeof(h_outer.l4hdr.udp);

		h_outer.l4hdr.udp.source = __bpf_constant_htons(cfg_udp_src);

		h_outer.l4hdr.udp.dest = bpf_htons(udp_dst);

		h_outer.l4hdr.udp.check = 0;

		h_outer.l4hdr.udp.len = bpf_htons(bpf_ntohs(iph_inner.tot_len) +

						  sizeof(h_outer.l4hdr.udp) +

						  l2_len);

		break;

	case IPPROTO_IPIP:

		break;

	default:

		return TC_ACT_OK;

	}



	/* add L2 encap (if specified) */

	switch (l2_proto) {

	case ETH_P_MPLS_UC:

		*((__u32 *)((__u8 *)&h_outer + olen)) = mpls_label;

		break;

	case ETH_P_TEB:

		if (bpf_skb_load_bytes(skb, 0, (__u8 *)&h_outer + olen,

				       ETH_HLEN))

			return TC_ACT_SHOT;

		break;

	}

	olen += l2_len;



	/* add room between mac and network header */

	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))

		return TC_ACT_SHOT;
@@ -85,16 +154,10 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre) 
	/* prepare new outer network header */

	h_outer.ip = iph_inner;

	h_outer.ip.tot_len = bpf_htons(olen +

				      bpf_htons(h_outer.ip.tot_len));

	if (with_gre) {

		h_outer.ip.protocol = IPPROTO_GRE;

		h_outer.protocol = bpf_htons(ETH_P_IP);

		h_outer.flags = 0;

	} else {

		h_outer.ip.protocol = IPPROTO_IPIP;

	}

				       bpf_ntohs(h_outer.ip.tot_len));

	h_outer.ip.protocol = encap_proto;



	set_ipv4_csum((void *)&h_outer.ip);

	set_ipv4_csum(&h_outer.ip);



	/* store new outer network header */

	if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
@@ -104,13 +167,16 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre) 
	return TC_ACT_OK;

}



static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)

static __always_inline int encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,

				      __u16 l2_proto)

{

	__u16 udp_dst = UDP_PORT;

	struct ipv6hdr iph_inner;

	struct grev6hdr h_outer;

	struct v6hdr h_outer;

	struct tcphdr tcph;

	int olen, l2_len;

	__u16 tot_len;

	__u64 flags;

	int olen;



	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,

			       sizeof(iph_inner)) < 0)
@@ -124,14 +190,58 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre) 
	if (tcph.dest != __bpf_constant_htons(cfg_port))

		return TC_ACT_OK;



	olen = sizeof(h_outer.ip);

	l2_len = 0;



	flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV6;

	if (with_gre) {



	switch (l2_proto) {

	case ETH_P_MPLS_UC:

		l2_len = sizeof(mpls_label);

		udp_dst = MPLS_OVER_UDP_PORT;

		break;

	case ETH_P_TEB:

		l2_len = ETH_HLEN;

		udp_dst = ETH_OVER_UDP_PORT;

		break;

	}

	flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);



	switch (encap_proto) {

	case IPPROTO_GRE:

		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;

		olen = sizeof(h_outer);

	} else {

		olen = sizeof(h_outer.ip);

		olen += sizeof(h_outer.l4hdr.gre);

		h_outer.l4hdr.gre.protocol = bpf_htons(l2_proto);

		h_outer.l4hdr.gre.flags = 0;

		break;

	case IPPROTO_UDP:

		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_UDP;

		olen += sizeof(h_outer.l4hdr.udp);

		h_outer.l4hdr.udp.source = __bpf_constant_htons(cfg_udp_src);

		h_outer.l4hdr.udp.dest = bpf_htons(udp_dst);

		tot_len = bpf_ntohs(iph_inner.payload_len) + sizeof(iph_inner) +

			  sizeof(h_outer.l4hdr.udp);

		h_outer.l4hdr.udp.check = 0;

		h_outer.l4hdr.udp.len = bpf_htons(tot_len);

		break;

	case IPPROTO_IPV6:

		break;

	default:

		return TC_ACT_OK;

	}



	/* add L2 encap (if specified) */

	switch (l2_proto) {

	case ETH_P_MPLS_UC:

		*((__u32 *)((__u8 *)&h_outer + olen)) = mpls_label;

		break;

	case ETH_P_TEB:

		if (bpf_skb_load_bytes(skb, 0, (__u8 *)&h_outer + olen,

				       ETH_HLEN))

			return TC_ACT_SHOT;

		break;

	}

	olen += l2_len;



	/* add room between mac and network header */

	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
@@ -141,13 +251,8 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre) 
	h_outer.ip = iph_inner;

	h_outer.ip.payload_len = bpf_htons(olen +

					   bpf_ntohs(h_outer.ip.payload_len));

	if (with_gre) {

		h_outer.ip.nexthdr = IPPROTO_GRE;

		h_outer.protocol = bpf_htons(ETH_P_IPV6);

		h_outer.flags = 0;

	} else {

		h_outer.ip.nexthdr = IPPROTO_IPV6;

	}



	h_outer.ip.nexthdr = encap_proto;



	/* store new outer network header */

	if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
@@ -157,54 +262,168 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre) 
	return TC_ACT_OK;

}



SEC("encap_ipip")

int __encap_ipip(struct __sk_buff *skb)

SEC("encap_ipip_none")

int __encap_ipip_none(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))

		return encap_ipv4(skb, false);

		return encap_ipv4(skb, IPPROTO_IPIP, ETH_P_IP);

	else

		return TC_ACT_OK;

}



SEC("encap_gre")

int __encap_gre(struct __sk_buff *skb)

SEC("encap_gre_none")

int __encap_gre_none(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))

		return encap_ipv4(skb, true);

		return encap_ipv4(skb, IPPROTO_GRE, ETH_P_IP);

	else

		return TC_ACT_OK;

}



SEC("encap_ip6tnl")

int __encap_ip6tnl(struct __sk_buff *skb)

SEC("encap_gre_mpls")

int __encap_gre_mpls(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))

		return encap_ipv4(skb, IPPROTO_GRE, ETH_P_MPLS_UC);

	else

		return TC_ACT_OK;

}



SEC("encap_gre_eth")

int __encap_gre_eth(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))

		return encap_ipv4(skb, IPPROTO_GRE, ETH_P_TEB);

	else

		return TC_ACT_OK;

}



SEC("encap_udp_none")

int __encap_udp_none(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))

		return encap_ipv4(skb, IPPROTO_UDP, ETH_P_IP);

	else

		return TC_ACT_OK;

}



SEC("encap_udp_mpls")

int __encap_udp_mpls(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))

		return encap_ipv4(skb, IPPROTO_UDP, ETH_P_MPLS_UC);

	else

		return TC_ACT_OK;

}



SEC("encap_udp_eth")

int __encap_udp_eth(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))

		return encap_ipv4(skb, IPPROTO_UDP, ETH_P_TEB);

	else

		return TC_ACT_OK;

}



SEC("encap_ip6tnl_none")

int __encap_ip6tnl_none(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))

		return encap_ipv6(skb, IPPROTO_IPV6, ETH_P_IPV6);

	else

		return TC_ACT_OK;

}



SEC("encap_ip6gre_none")

int __encap_ip6gre_none(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))

		return encap_ipv6(skb, IPPROTO_GRE, ETH_P_IPV6);

	else

		return TC_ACT_OK;

}



SEC("encap_ip6gre_mpls")

int __encap_ip6gre_mpls(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))

		return encap_ipv6(skb, IPPROTO_GRE, ETH_P_MPLS_UC);

	else

		return TC_ACT_OK;

}



SEC("encap_ip6gre_eth")

int __encap_ip6gre_eth(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))

		return encap_ipv6(skb, IPPROTO_GRE, ETH_P_TEB);

	else

		return TC_ACT_OK;

}



SEC("encap_ip6udp_none")

int __encap_ip6udp_none(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))

		return encap_ipv6(skb, false);

		return encap_ipv6(skb, IPPROTO_UDP, ETH_P_IPV6);

	else

		return TC_ACT_OK;

}



SEC("encap_ip6gre")

int __encap_ip6gre(struct __sk_buff *skb)

SEC("encap_ip6udp_mpls")

int __encap_ip6udp_mpls(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))

		return encap_ipv6(skb, true);

		return encap_ipv6(skb, IPPROTO_UDP, ETH_P_MPLS_UC);

	else

		return TC_ACT_OK;

}



SEC("encap_ip6udp_eth")

int __encap_ip6udp_eth(struct __sk_buff *skb)

{

	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))

		return encap_ipv6(skb, IPPROTO_UDP, ETH_P_TEB);

	else

		return TC_ACT_OK;

}



static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)

{

	char buf[sizeof(struct grev6hdr)];

	int olen;

	char buf[sizeof(struct v6hdr)];

	struct gre_hdr greh;

	struct udphdr udph;

	int olen = len;



	switch (proto) {

	case IPPROTO_IPIP:

	case IPPROTO_IPV6:

		olen = len;

		break;

	case IPPROTO_GRE:

		olen = len + 4 /* gre hdr */;

		olen += sizeof(struct gre_hdr);

		if (bpf_skb_load_bytes(skb, off + len, &greh, sizeof(greh)) < 0)

			return TC_ACT_OK;

		switch (bpf_ntohs(greh.protocol)) {

		case ETH_P_MPLS_UC:

			olen += sizeof(mpls_label);

			break;

		case ETH_P_TEB:

			olen += ETH_HLEN;

			break;

		}

		break;

	case IPPROTO_UDP:

		olen += sizeof(struct udphdr);

		if (bpf_skb_load_bytes(skb, off + len, &udph, sizeof(udph)) < 0)

			return TC_ACT_OK;

		switch (bpf_ntohs(udph.dest)) {

		case MPLS_OVER_UDP_PORT:

			olen += sizeof(mpls_label);

			break;

		case ETH_OVER_UDP_PORT:

			olen += ETH_HLEN;

			break;

		}

		break;

	default:

		return TC_ACT_OK;

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