Re: [PATCH/v4] bpf: add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_ENCAP_L2_ETH

From: Xuesen Huang
Date: Wed Mar 03 2021 - 12:11:39 EST

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In reply to: Xuesen Huang: "[PATCH/v4] bpf: add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_ENCAP_L2_ETH"
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Thanks Cong!

Thanks to your suggestion, I try to add a simple test case to test_tc_tunnel. It works
for me :)

Thanks for your review.

> 2021年3月3日下午8:33，Xuesen Huang <hxseverything@xxxxxxxxx> 写道：
>
> From: Xuesen Huang <huangxuesen@xxxxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: Xuesen Huang <huangxuesen@xxxxxxxxxxxx>
> Signed-off-by: Zhiyong Cheng <chengzhiyong@xxxxxxxxxxxx>
> Signed-off-by: Li Wang <wangli09@xxxxxxxxxxxx>
> ---
> 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
>

Next message: Michal Hocko: "Re: [PATCH 1/2] mm: disable LRU pagevec during the migration temporarily"
Previous message: Mark Brown: "Re: [PATCH] SoC: codecs: fix platform_no_drv_owner.cocci warnings"
In reply to: Xuesen Huang: "[PATCH/v4] bpf: add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_ENCAP_L2_ETH"
Next in thread: Willem de Bruijn: "Re: [PATCH/v4] bpf: add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_ENCAP_L2_ETH"
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