From: Xuesen Huang <huangxue...@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 <will...@google.com>
Signed-off-by: Xuesen Huang <huangxue...@kuaishou.com>
Signed-off-by: Zhiyong Cheng <chengzhiy...@kuaishou.com>
Signed-off-by: Li Wang <wangl...@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

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