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From:   Xuesen Huang <hxseverything@gmail.com>
To:     daniel@iogearbox.net
Cc:     davem@davemloft.net, bpf@vger.kernel.org,
        willemdebruijn.kernel@gmail.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, xiyou.wangcong@gmail.com,
        Xuesen Huang <huangxuesen@kuaishou.com>,
        Willem de Bruijn <willemb@google.com>,
        Zhiyong Cheng <chengzhiyong@kuaishou.com>,
        Li Wang <wangli09@kuaishou.com>
Subject: [PATCH/v4] bpf: add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_ENCAP_L2_ETH
Date:   Wed,  3 Mar 2021 20:33:38 +0800
Message-Id: <20210303123338.99089-1-hxseverything@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Xuesen Huang <huangxuesen@kuaishou.com>

bpf_skb_adjust_room sets the inner_protocol as skb->protocol for packets
encapsulation. But that is not appropriate when pushing Ethernet header.

Add an option to further specify encap L2 type and set the inner_protocol
as ETH_P_TEB.

Update test_tc_tunnel to verify adding vxlan encapsulation works with
this flag.

Suggested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Xuesen Huang <huangxuesen@kuaishou.com>
Signed-off-by: Zhiyong Cheng <chengzhiyong@kuaishou.com>
Signed-off-by: Li Wang <wangli09@kuaishou.com>
---
 include/uapi/linux/bpf.h                           |   5 +
 net/core/filter.c                                  |  11 ++-
 tools/include/uapi/linux/bpf.h                     |   5 +
 tools/testing/selftests/bpf/progs/test_tc_tunnel.c | 107 ++++++++++++++++++---
 tools/testing/selftests/bpf/test_tc_tunnel.sh      |  15 ++-
 5 files changed, 124 insertions(+), 19 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 77d7c1b..d791596 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1751,6 +1751,10 @@ struct bpf_stack_build_id {
  *		  Use with ENCAP_L3/L4 flags to further specify the tunnel
  *		  type; *len* is the length of the inner MAC header.
  *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L2_ETH**:
+ *		  Use with BPF_F_ADJ_ROOM_ENCAP_L2 flag to further specify the
+ *		  L2 type as Ethernet.
+ *
  * 		A call to this helper is susceptible to change the underlying
  * 		packet buffer. Therefore, at load time, all checks on pointers
  * 		previously done by the verifier are invalidated and must be
@@ -4088,6 +4092,7 @@ enum {
 	BPF_F_ADJ_ROOM_ENCAP_L4_GRE	= (1ULL << 3),
 	BPF_F_ADJ_ROOM_ENCAP_L4_UDP	= (1ULL << 4),
 	BPF_F_ADJ_ROOM_NO_CSUM_RESET	= (1ULL << 5),
+	BPF_F_ADJ_ROOM_ENCAP_L2_ETH	= (1ULL << 6),
 };
 
 enum {
diff --git a/net/core/filter.c b/net/core/filter.c
index 255aeee..8d1fb61 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3412,6 +3412,7 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb)
 					 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_L2_ETH | \
 					 BPF_F_ADJ_ROOM_ENCAP_L2( \
 					  BPF_ADJ_ROOM_ENCAP_L2_MASK))
 
@@ -3448,6 +3449,10 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
 		    flags & BPF_F_ADJ_ROOM_ENCAP_L4_UDP)
 			return -EINVAL;
 
+		if (flags & BPF_F_ADJ_ROOM_ENCAP_L2_ETH &&
+		    inner_mac_len < ETH_HLEN)
+			return -EINVAL;
+
 		if (skb->encapsulation)
 			return -EALREADY;
 
@@ -3466,7 +3471,11 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
 		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);
+
+		if (flags & BPF_F_ADJ_ROOM_ENCAP_L2_ETH)
+			skb_set_inner_protocol(skb, htons(ETH_P_TEB));
+		else
+			skb_set_inner_protocol(skb, skb->protocol);
 
 		skb->encapsulation = 1;
 		skb_set_network_header(skb, mac_len);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 77d7c1b..d791596 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1751,6 +1751,10 @@ struct bpf_stack_build_id {
  *		  Use with ENCAP_L3/L4 flags to further specify the tunnel
  *		  type; *len* is the length of the inner MAC header.
  *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L2_ETH**:
+ *		  Use with BPF_F_ADJ_ROOM_ENCAP_L2 flag to further specify the
+ *		  L2 type as Ethernet.
+ *
  * 		A call to this helper is susceptible to change the underlying
  * 		packet buffer. Therefore, at load time, all checks on pointers
  * 		previously done by the verifier are invalidated and must be
@@ -4088,6 +4092,7 @@ enum {
 	BPF_F_ADJ_ROOM_ENCAP_L4_GRE	= (1ULL << 3),
 	BPF_F_ADJ_ROOM_ENCAP_L4_UDP	= (1ULL << 4),
 	BPF_F_ADJ_ROOM_NO_CSUM_RESET	= (1ULL << 5),
+	BPF_F_ADJ_ROOM_ENCAP_L2_ETH	= (1ULL << 6),
 };
 
 enum {
diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index 37bce7a..6e144db 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -20,6 +20,14 @@
 #include <bpf/bpf_endian.h>
 #include <bpf/bpf_helpers.h>
 
+#define encap_ipv4(...) __encap_ipv4(__VA_ARGS__, 0)
+
+#define encap_ipv4_with_ext_proto(...) __encap_ipv4(__VA_ARGS__)
+
+#define encap_ipv6(...) __encap_ipv6(__VA_ARGS__, 0)
+
+#define encap_ipv6_with_ext_proto(...) __encap_ipv6(__VA_ARGS__)
+
 static const int cfg_port = 8000;
 
 static const int cfg_udp_src = 20000;
@@ -27,11 +35,24 @@
 #define	UDP_PORT		5555
 #define	MPLS_OVER_UDP_PORT	6635
 #define	ETH_OVER_UDP_PORT	7777
+#define	VXLAN_UDP_PORT		8472
+
+#define	EXTPROTO_VXLAN	0x1
+
+#define	VXLAN_N_VID     (1u << 24)
+#define	VXLAN_VNI_MASK	bpf_htonl((VXLAN_N_VID - 1) << 8)
+#define	VXLAN_FLAGS     0x8
+#define	VXLAN_VNI       1
 
 /* 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 vxlanhdr {
+	__be32 vx_flags;
+	__be32 vx_vni;
+} __attribute__((packed));
+
 struct gre_hdr {
 	__be16 flags;
 	__be16 protocol;
@@ -45,13 +66,13 @@ struct gre_hdr {
 struct v4hdr {
 	struct iphdr ip;
 	union l4hdr l4hdr;
-	__u8 pad[16];			/* enough space for L2 header */
+	__u8 pad[24];			/* space for L2 header / vxlan header ... */
 } __attribute__((packed));
 
 struct v6hdr {
 	struct ipv6hdr ip;
 	union l4hdr l4hdr;
-	__u8 pad[16];			/* enough space for L2 header */
+	__u8 pad[24];			/* space for L2 header / vxlan header ... */
 } __attribute__((packed));
 
 static __always_inline void set_ipv4_csum(struct iphdr *iph)
@@ -69,14 +90,15 @@ 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, __u8 encap_proto,
-				      __u16 l2_proto)
+static __always_inline int __encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
+				      __u16 l2_proto, __u16 ext_proto)
 {
 	__u16 udp_dst = UDP_PORT;
 	struct iphdr iph_inner;
 	struct v4hdr h_outer;
 	struct tcphdr tcph;
 	int olen, l2_len;
+	__u8 *l2_hdr = NULL;
 	int tcp_off;
 	__u64 flags;
 
@@ -141,7 +163,11 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
 		break;
 	case ETH_P_TEB:
 		l2_len = ETH_HLEN;
-		udp_dst = ETH_OVER_UDP_PORT;
+		if (ext_proto & EXTPROTO_VXLAN) {
+			udp_dst = VXLAN_UDP_PORT;
+			l2_len += sizeof(struct vxlanhdr);
+		} else
+			udp_dst = ETH_OVER_UDP_PORT;
 		break;
 	}
 	flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);
@@ -171,14 +197,26 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
 	}
 
 	/* add L2 encap (if specified) */
+	l2_hdr = (__u8 *)&h_outer + olen;
 	switch (l2_proto) {
 	case ETH_P_MPLS_UC:
-		*((__u32 *)((__u8 *)&h_outer + olen)) = mpls_label;
+		*(__u32 *)l2_hdr = mpls_label;
 		break;
 	case ETH_P_TEB:
-		if (bpf_skb_load_bytes(skb, 0, (__u8 *)&h_outer + olen,
-				       ETH_HLEN))
+		flags |= BPF_F_ADJ_ROOM_ENCAP_L2_ETH;
+
+		if (ext_proto & EXTPROTO_VXLAN) {
+			struct vxlanhdr *vxlan_hdr = (struct vxlanhdr *)l2_hdr;
+
+			vxlan_hdr->vx_flags = VXLAN_FLAGS;
+			vxlan_hdr->vx_vni = bpf_htonl((VXLAN_VNI & VXLAN_VNI_MASK) << 8);
+
+			l2_hdr += sizeof(struct vxlanhdr);
+		}
+
+		if (bpf_skb_load_bytes(skb, 0, l2_hdr, ETH_HLEN))
 			return TC_ACT_SHOT;
+
 		break;
 	}
 	olen += l2_len;
@@ -214,14 +252,15 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
 	return TC_ACT_OK;
 }
 
-static __always_inline int encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
-				      __u16 l2_proto)
+static __always_inline int __encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
+				      __u16 l2_proto, __u16 ext_proto)
 {
 	__u16 udp_dst = UDP_PORT;
 	struct ipv6hdr iph_inner;
 	struct v6hdr h_outer;
 	struct tcphdr tcph;
 	int olen, l2_len;
+	__u8 *l2_hdr = NULL;
 	__u16 tot_len;
 	__u64 flags;
 
@@ -249,7 +288,11 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
 		break;
 	case ETH_P_TEB:
 		l2_len = ETH_HLEN;
-		udp_dst = ETH_OVER_UDP_PORT;
+		if (ext_proto & EXTPROTO_VXLAN) {
+			udp_dst = VXLAN_UDP_PORT;
+			l2_len += sizeof(struct vxlanhdr);
+		} else
+			udp_dst = ETH_OVER_UDP_PORT;
 		break;
 	}
 	flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);
@@ -267,7 +310,7 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
 		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);
+			  sizeof(h_outer.l4hdr.udp) + l2_len;
 		h_outer.l4hdr.udp.check = 0;
 		h_outer.l4hdr.udp.len = bpf_htons(tot_len);
 		break;
@@ -278,13 +321,24 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, __u8 encap_proto,
 	}
 
 	/* add L2 encap (if specified) */
+	l2_hdr = (__u8 *)&h_outer + olen;
 	switch (l2_proto) {
 	case ETH_P_MPLS_UC:
-		*((__u32 *)((__u8 *)&h_outer + olen)) = mpls_label;
+		*(__u32 *)l2_hdr = mpls_label;
 		break;
 	case ETH_P_TEB:
-		if (bpf_skb_load_bytes(skb, 0, (__u8 *)&h_outer + olen,
-				       ETH_HLEN))
+		flags |= BPF_F_ADJ_ROOM_ENCAP_L2_ETH;
+
+		if (ext_proto & EXTPROTO_VXLAN) {
+			struct vxlanhdr *vxlan_hdr = (struct vxlanhdr *)l2_hdr;
+
+			vxlan_hdr->vx_flags = VXLAN_FLAGS;
+			vxlan_hdr->vx_vni = bpf_htonl((VXLAN_VNI & VXLAN_VNI_MASK) << 8);
+
+			l2_hdr += sizeof(struct vxlanhdr);
+		}
+
+		if (bpf_skb_load_bytes(skb, 0, l2_hdr, ETH_HLEN))
 			return TC_ACT_SHOT;
 		break;
 	}
@@ -372,6 +426,16 @@ int __encap_udp_eth(struct __sk_buff *skb)
 		return TC_ACT_OK;
 }
 
+SEC("encap_vxlan_eth")
+int __encap_vxlan_eth(struct __sk_buff *skb)
+{
+	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
+		return encap_ipv4_with_ext_proto(skb, IPPROTO_UDP,
+				ETH_P_TEB, EXTPROTO_VXLAN);
+	else
+		return TC_ACT_OK;
+}
+
 SEC("encap_sit_none")
 int __encap_sit_none(struct __sk_buff *skb)
 {
@@ -444,6 +508,16 @@ int __encap_ip6udp_eth(struct __sk_buff *skb)
 		return TC_ACT_OK;
 }
 
+SEC("encap_ip6vxlan_eth")
+int __encap_ip6vxlan_eth(struct __sk_buff *skb)
+{
+	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
+		return encap_ipv6_with_ext_proto(skb, IPPROTO_UDP,
+				ETH_P_TEB, EXTPROTO_VXLAN);
+	else
+		return TC_ACT_OK;
+}
+
 static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
 {
 	char buf[sizeof(struct v6hdr)];
@@ -479,6 +553,9 @@ static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
 		case ETH_OVER_UDP_PORT:
 			olen += ETH_HLEN;
 			break;
+		case VXLAN_UDP_PORT:
+			olen += ETH_HLEN + sizeof(struct vxlanhdr);
+			break;
 		}
 		break;
 	default:
diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
index 7c76b84..c9dde9b 100755
--- a/tools/testing/selftests/bpf/test_tc_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -44,8 +44,8 @@ setup() {
 	# clamp route to reserve room for tunnel headers
 	ip -netns "${ns1}" -4 route flush table main
 	ip -netns "${ns1}" -6 route flush table main
-	ip -netns "${ns1}" -4 route add "${ns2_v4}" mtu 1458 dev veth1
-	ip -netns "${ns1}" -6 route add "${ns2_v6}" mtu 1438 dev veth1
+	ip -netns "${ns1}" -4 route add "${ns2_v4}" mtu 1450 dev veth1
+	ip -netns "${ns1}" -6 route add "${ns2_v6}" mtu 1430 dev veth1
 
 	sleep 1
 
@@ -105,6 +105,12 @@ if [[ "$#" -eq "0" ]]; then
 	echo "sit"
 	$0 ipv6 sit none 100
 
+	echo "ip4 vxlan"
+	$0 ipv4 vxlan eth 2000
+
+	echo "ip6 vxlan"
+	$0 ipv6 ip6vxlan eth 2000
+
 	for mac in none mpls eth ; do
 		echo "ip gre $mac"
 		$0 ipv4 gre $mac 100
@@ -214,6 +220,9 @@ if [[ "$tuntype" =~ "udp" ]]; then
 	targs="encap fou encap-sport auto encap-dport $dport"
 elif [[ "$tuntype" =~ "gre" && "$mac" == "eth" ]]; then
 	ttype=$gretaptype
+elif [[ "$tuntype" =~ "vxlan" && "$mac" == "eth" ]]; then
+	ttype="vxlan"
+	targs="id 1 dstport 8472 udp6zerocsumrx"
 else
 	ttype=$tuntype
 	targs=""
@@ -242,7 +251,7 @@ if [[ "$tuntype" == "ip6udp" && "$mac" == "mpls" ]]; then
 elif [[ "$tuntype" =~ "udp" && "$mac" == "eth" ]]; then
 	# No support for TEB fou tunnel; expect failure.
 	expect_tun_fail=1
-elif [[ "$tuntype" =~ "gre" && "$mac" == "eth" ]]; then
+elif [[ "$tuntype" =~ (gre|vxlan) && "$mac" == "eth" ]]; then
 	# Share ethernet address between tunnel/veth2 so L2 decap works.
 	ethaddr=$(ip netns exec "${ns2}" ip link show veth2 | \
 		  awk '/ether/ { print $2 }')
-- 
1.8.3.1