[PATCH net-next 0/3] virtio_net: add optional flow dissection in virtio_net_hdr_to_skb

[PATCH net-next 0/3] virtio_net: add optional flow dissection in virtio_net_hdr_to_skb

[Tanner Love]

From: Tanner Love <tannerlove@google.com>

First patch extends the flow dissector BPF program type to accept
virtio-net header members.

Second patch uses this feature to add optional flow dissection in
virtio_net_hdr_to_skb(). This allows admins to define permitted
packets more strictly, for example dropping deprecated UDP_UFO
packets.

Third patch extends kselftest to cover this feature.

Tanner Love (3):
  net: flow_dissector: extend bpf flow dissector support with vnet hdr
  virtio_net: add optional flow dissection in virtio_net_hdr_to_skb
  selftests/net: amend bpf flow dissector prog to do vnet hdr validation

 drivers/net/bonding/bond_main.c               |   2 +-
 include/linux/skbuff.h                        |  26 ++-
 include/linux/virtio_net.h                    |  27 ++-
 include/net/flow_dissector.h                  |   6 +
 include/uapi/linux/bpf.h                      |   6 +
 net/core/filter.c                             |  55 ++++++
 net/core/flow_dissector.c                     |  23 ++-
 net/core/sysctl_net_core.c                    |  10 +
 tools/include/uapi/linux/bpf.h                |   6 +
 tools/testing/selftests/bpf/progs/bpf_flow.c  | 187 +++++++++++++-----
 .../selftests/bpf/test_flow_dissector.c       | 181 ++++++++++++++---
 .../selftests/bpf/test_flow_dissector.sh      |  19 ++
 12 files changed, 469 insertions(+), 79 deletions(-)

-- 
2.32.0.rc0.204.g9fa02ecfa5-goog

[PATCH net-next 1/3] net: flow_dissector: extend bpf flow dissector support with vnet hdr

[Tanner Love]

From: Tanner Love <tannerlove@google.com>

Amend the bpf flow dissector program type to accept virtio_net_hdr
members. Do this to enable bpf flow dissector programs to perform
virtio-net header validation. The next patch in this series will add
a flow dissection hook in virtio_net_hdr_to_skb and make use of this
extended functionality. That commit message has more background on the
use case.

Signed-off-by: Tanner Love <tannerlove@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Petar Penkov <ppenkov@google.com>
---
 drivers/net/bonding/bond_main.c |  2 +-
 include/linux/skbuff.h          | 26 ++++++++++++----
 include/net/flow_dissector.h    |  6 ++++
 include/uapi/linux/bpf.h        |  6 ++++
 net/core/filter.c               | 55 +++++++++++++++++++++++++++++++++
 net/core/flow_dissector.c       | 23 ++++++++++++--
 tools/include/uapi/linux/bpf.h  |  6 ++++
 7 files changed, 115 insertions(+), 9 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 7e469c203ca5..5d2d7d5c5704 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3554,7 +3554,7 @@ static bool bond_flow_dissect(struct bonding *bond, struct sk_buff *skb,
 	case BOND_XMIT_POLICY_ENCAP34:
 		memset(fk, 0, sizeof(*fk));
 		return __skb_flow_dissect(NULL, skb, &flow_keys_bonding,
-					  fk, NULL, 0, 0, 0, 0);
+					  fk, NULL, 0, 0, 0, 0, NULL);
 	default:
 		break;
 	}
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index dbf820a50a39..fef8f4b5db6e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1312,18 +1312,20 @@ struct bpf_flow_dissector;
 bool bpf_flow_dissect(struct bpf_prog *prog, struct bpf_flow_dissector *ctx,
 		      __be16 proto, int nhoff, int hlen, unsigned int flags);
 
+struct virtio_net_hdr;
 bool __skb_flow_dissect(const struct net *net,
 			const struct sk_buff *skb,
 			struct flow_dissector *flow_dissector,
 			void *target_container, const void *data,
-			__be16 proto, int nhoff, int hlen, unsigned int flags);
+			__be16 proto, int nhoff, int hlen, unsigned int flags,
+			const struct virtio_net_hdr *vhdr);
 
 static inline bool skb_flow_dissect(const struct sk_buff *skb,
 				    struct flow_dissector *flow_dissector,
 				    void *target_container, unsigned int flags)
 {
 	return __skb_flow_dissect(NULL, skb, flow_dissector,
-				  target_container, NULL, 0, 0, 0, flags);
+				  target_container, NULL, 0, 0, 0, flags, NULL);
 }
 
 static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb,
@@ -1332,7 +1334,20 @@ static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb,
 {
 	memset(flow, 0, sizeof(*flow));
 	return __skb_flow_dissect(NULL, skb, &flow_keys_dissector,
-				  flow, NULL, 0, 0, 0, flags);
+				  flow, NULL, 0, 0, 0, flags, NULL);
+}
+
+static inline bool
+__skb_flow_dissect_flow_keys_basic(const struct net *net,
+				   const struct sk_buff *skb,
+				   struct flow_keys_basic *flow,
+				   const void *data, __be16 proto,
+				   int nhoff, int hlen, unsigned int flags,
+				   const struct virtio_net_hdr *vhdr)
+{
+	memset(flow, 0, sizeof(*flow));
+	return __skb_flow_dissect(net, skb, &flow_keys_basic_dissector, flow,
+				  data, proto, nhoff, hlen, flags, vhdr);
 }
 
 static inline bool
@@ -1342,9 +1357,8 @@ skb_flow_dissect_flow_keys_basic(const struct net *net,
 				 const void *data, __be16 proto,
 				 int nhoff, int hlen, unsigned int flags)
 {
-	memset(flow, 0, sizeof(*flow));
-	return __skb_flow_dissect(net, skb, &flow_keys_basic_dissector, flow,
-				  data, proto, nhoff, hlen, flags);
+	return __skb_flow_dissect_flow_keys_basic(net, skb, flow, data, proto,
+						  nhoff, hlen, flags, NULL);
 }
 
 void skb_flow_dissect_meta(const struct sk_buff *skb,
diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index ffd386ea0dbb..0796ad745e69 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -370,6 +370,12 @@ struct bpf_flow_dissector {
 	const struct sk_buff	*skb;
 	const void		*data;
 	const void		*data_end;
+	__u8			vhdr_flags;
+	__u8			vhdr_gso_type;
+	__u16			vhdr_hdr_len;
+	__u16			vhdr_gso_size;
+	__u16			vhdr_csum_start;
+	__u16			vhdr_csum_offset;
 };
 
 static inline void
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 418b9b813d65..de525defd462 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5155,6 +5155,12 @@ struct __sk_buff {
 	__u32 gso_segs;
 	__bpf_md_ptr(struct bpf_sock *, sk);
 	__u32 gso_size;
+	__u8  vhdr_flags;
+	__u8  vhdr_gso_type;
+	__u16 vhdr_hdr_len;
+	__u16 vhdr_gso_size;
+	__u16 vhdr_csum_start;
+	__u16 vhdr_csum_offset;
 };
 
 struct bpf_tunnel_key {
diff --git a/net/core/filter.c b/net/core/filter.c
index 239de1306de9..af45e769ced6 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8358,6 +8358,16 @@ static bool flow_dissector_is_valid_access(int off, int size,
 			return false;
 		info->reg_type = PTR_TO_FLOW_KEYS;
 		return true;
+	case bpf_ctx_range(struct __sk_buff, len):
+		return size == size_default;
+	case bpf_ctx_range(struct __sk_buff, vhdr_flags):
+	case bpf_ctx_range(struct __sk_buff, vhdr_gso_type):
+		return size == sizeof(__u8);
+	case bpf_ctx_range(struct __sk_buff, vhdr_hdr_len):
+	case bpf_ctx_range(struct __sk_buff, vhdr_gso_size):
+	case bpf_ctx_range(struct __sk_buff, vhdr_csum_start):
+	case bpf_ctx_range(struct __sk_buff, vhdr_csum_offset):
+		return size == sizeof(__u16);
 	default:
 		return false;
 	}
@@ -8390,6 +8400,51 @@ static u32 flow_dissector_convert_ctx_access(enum bpf_access_type type,
 				      si->dst_reg, si->src_reg,
 				      offsetof(struct bpf_flow_dissector, flow_keys));
 		break;
+
+	case offsetof(struct __sk_buff, vhdr_flags):
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_flow_dissector, vhdr_flags),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct bpf_flow_dissector, vhdr_flags));
+		break;
+
+	case offsetof(struct __sk_buff, vhdr_gso_type):
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_flow_dissector, vhdr_gso_type),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct bpf_flow_dissector, vhdr_gso_type));
+		break;
+
+	case offsetof(struct __sk_buff, vhdr_hdr_len):
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_flow_dissector, vhdr_hdr_len),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct bpf_flow_dissector, vhdr_hdr_len));
+		break;
+
+	case offsetof(struct __sk_buff, vhdr_gso_size):
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_flow_dissector, vhdr_gso_size),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct bpf_flow_dissector, vhdr_gso_size));
+		break;
+
+	case offsetof(struct __sk_buff, vhdr_csum_start):
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_flow_dissector, vhdr_csum_start),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct bpf_flow_dissector, vhdr_csum_start));
+		break;
+
+	case offsetof(struct __sk_buff, vhdr_csum_offset):
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_flow_dissector, vhdr_csum_offset),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct bpf_flow_dissector, vhdr_csum_offset));
+		break;
+
+	case offsetof(struct __sk_buff, len):
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_flow_dissector, skb),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct bpf_flow_dissector, skb));
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, len),
+				      si->dst_reg, si->dst_reg,
+				      offsetof(struct sk_buff, len));
+		break;
 	}
 
 	return insn - insn_buf;
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 3ed7c98a98e1..59639ad8700d 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -28,6 +28,7 @@
 #include <scsi/fc/fc_fcoe.h>
 #include <uapi/linux/batadv_packet.h>
 #include <linux/bpf.h>
+#include <linux/virtio_net.h>
 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
 #include <net/netfilter/nf_conntrack_core.h>
 #include <net/netfilter/nf_conntrack_labels.h>
@@ -915,7 +916,8 @@ bool __skb_flow_dissect(const struct net *net,
 			const struct sk_buff *skb,
 			struct flow_dissector *flow_dissector,
 			void *target_container, const void *data,
-			__be16 proto, int nhoff, int hlen, unsigned int flags)
+			__be16 proto, int nhoff, int hlen, unsigned int flags,
+			const struct virtio_net_hdr *vhdr)
 {
 	struct flow_dissector_key_control *key_control;
 	struct flow_dissector_key_basic *key_basic;
@@ -1001,6 +1003,23 @@ bool __skb_flow_dissect(const struct net *net,
 			__be16 n_proto = proto;
 			struct bpf_prog *prog;
 
+			if (vhdr) {
+				ctx.vhdr_flags = vhdr->flags;
+				ctx.vhdr_gso_type = vhdr->gso_type;
+				ctx.vhdr_hdr_len =
+					__virtio16_to_cpu(virtio_legacy_is_little_endian(),
+							  vhdr->hdr_len);
+				ctx.vhdr_gso_size =
+					__virtio16_to_cpu(virtio_legacy_is_little_endian(),
+							  vhdr->gso_size);
+				ctx.vhdr_csum_start =
+					__virtio16_to_cpu(virtio_legacy_is_little_endian(),
+							  vhdr->csum_start);
+				ctx.vhdr_csum_offset =
+					__virtio16_to_cpu(virtio_legacy_is_little_endian(),
+							  vhdr->csum_offset);
+			}
+
 			if (skb) {
 				ctx.skb = skb;
 				/* we can't use 'proto' in the skb case
@@ -1610,7 +1629,7 @@ u32 __skb_get_hash_symmetric(const struct sk_buff *skb)
 	memset(&keys, 0, sizeof(keys));
 	__skb_flow_dissect(NULL, skb, &flow_keys_dissector_symmetric,
 			   &keys, NULL, 0, 0, 0,
-			   FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL);
+			   FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL, NULL);
 
 	return __flow_hash_from_keys(&keys, &hashrnd);
 }
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 418b9b813d65..de525defd462 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5155,6 +5155,12 @@ struct __sk_buff {
 	__u32 gso_segs;
 	__bpf_md_ptr(struct bpf_sock *, sk);
 	__u32 gso_size;
+	__u8  vhdr_flags;
+	__u8  vhdr_gso_type;
+	__u16 vhdr_hdr_len;
+	__u16 vhdr_gso_size;
+	__u16 vhdr_csum_start;
+	__u16 vhdr_csum_offset;
 };
 
 struct bpf_tunnel_key {
-- 
2.32.0.rc0.204.g9fa02ecfa5-goog

[PATCH net-next 2/3] virtio_net: add optional flow dissection in virtio_net_hdr_to_skb

[Tanner Love]

From: Tanner Love <tannerlove@google.com>

Syzkaller bugs have resulted from loose specification of
virtio_net_hdr[1]. Enable execution of a BPF flow dissector program
in virtio_net_hdr_to_skb to validate the vnet header and drop bad
input.

The existing behavior of accepting these vnet headers is part of the
ABI. But individual admins may want to enforce restrictions. For
example, verifying that a GSO_TCPV4 gso_type matches packet contents:
unencapsulated TCP/IPV4 packet with payload exceeding gso_size and
hdr_len at payload offset.

Introduce a new sysctl net.core.flow_dissect_vnet_hdr controlling a
static key to decide whether to perform flow dissection. When the key
is false, virtio_net_hdr_to_skb computes as before.

[1] https://syzkaller.appspot.com/bug?id=b419a5ca95062664fe1a60b764621eb4526e2cd0

Signed-off-by: Tanner Love <tannerlove@google.com>
Suggested-by: Willem de Bruijn <willemb@google.com>
---
 include/linux/virtio_net.h | 27 +++++++++++++++++++++++----
 net/core/sysctl_net_core.c | 10 ++++++++++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index b465f8f3e554..a92fcf38087d 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -3,6 +3,8 @@
 #define _LINUX_VIRTIO_NET_H
 
 #include <linux/if_vlan.h>
+#include <linux/jump_label.h>
+#include <net/sock.h>
 #include <uapi/linux/tcp.h>
 #include <uapi/linux/udp.h>
 #include <uapi/linux/virtio_net.h>
@@ -25,10 +27,13 @@ static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
 	return 0;
 }
 
+DECLARE_STATIC_KEY_FALSE(sysctl_flow_dissect_vnet_hdr_key);
+
 static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
 					const struct virtio_net_hdr *hdr,
 					bool little_endian)
 {
+	struct flow_keys_basic keys;
 	unsigned int gso_type = 0;
 	unsigned int thlen = 0;
 	unsigned int p_off = 0;
@@ -78,13 +83,24 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
 		p_off = skb_transport_offset(skb) + thlen;
 		if (!pskb_may_pull(skb, p_off))
 			return -EINVAL;
-	} else {
+	}
+
+	/* BPF flow dissection for optional strict validation.
+	 *
+	 * Admins can define permitted packets more strictly, such as dropping
+	 * deprecated UDP_UFO packets and requiring skb->protocol to be non-zero
+	 * and matching packet headers.
+	 */
+	if (static_branch_unlikely(&sysctl_flow_dissect_vnet_hdr_key) &&
+	    !__skb_flow_dissect_flow_keys_basic(NULL, skb, &keys, NULL, 0, 0, 0,
+						0, hdr))
+		return -EINVAL;
+
+	if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM)) {
 		/* gso packets without NEEDS_CSUM do not set transport_offset.
 		 * probe and drop if does not match one of the above types.
 		 */
 		if (gso_type && skb->network_header) {
-			struct flow_keys_basic keys;
-
 			if (!skb->protocol) {
 				__be16 protocol = dev_parse_header_protocol(skb);
 
@@ -92,8 +108,11 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
 				if (protocol && protocol != skb->protocol)
 					return -EINVAL;
 			}
+
 retry:
-			if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
+			/* only if flow dissection not already done */
+			if (!static_branch_unlikely(&sysctl_flow_dissect_vnet_hdr_key) &&
+			    !skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
 							      NULL, 0, 0, 0,
 							      0)) {
 				/* UFO does not specify ipv4 or 6: try both */
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index c8496c1142c9..277eb6ba3b01 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -36,6 +36,9 @@ static int net_msg_warn;	/* Unused, but still a sysctl */
 int sysctl_fb_tunnels_only_for_init_net __read_mostly = 0;
 EXPORT_SYMBOL(sysctl_fb_tunnels_only_for_init_net);
 
+DEFINE_STATIC_KEY_FALSE(sysctl_flow_dissect_vnet_hdr_key);
+EXPORT_SYMBOL(sysctl_flow_dissect_vnet_hdr_key);
+
 /* 0 - Keep current behavior:
  *     IPv4: inherit all current settings from init_net
  *     IPv6: reset all settings to default
@@ -580,6 +583,13 @@ static struct ctl_table net_core_table[] = {
 		.extra1		= SYSCTL_ONE,
 		.extra2		= &int_3600,
 	},
+	{
+		.procname       = "flow_dissect_vnet_hdr",
+		.data           = &sysctl_flow_dissect_vnet_hdr_key.key,
+		.maxlen         = sizeof(sysctl_flow_dissect_vnet_hdr_key),
+		.mode           = 0644,
+		.proc_handler   = proc_do_static_key,
+	},
 	{ }
 };
 
-- 
2.32.0.rc0.204.g9fa02ecfa5-goog

[PATCH net-next 3/3] selftests/net: amend bpf flow dissector prog to do vnet hdr validation

[Tanner Love]

From: Tanner Love <tannerlove@google.com>

Change the BPF flow dissector program to perform various checks on the
virtio_net_hdr fields after doing flow dissection.

Amend test_flow_dissector.(c|sh) to add test cases that inject packets
with reasonable or unreasonable virtio-net headers and assert that bad
packets are dropped and good packets are not. Do this via packet
socket; the kernel executes tpacket_snd, which enters
virtio_net_hdr_to_skb, where flow dissection / vnet header validation
occurs.

Signed-off-by: Tanner Love <tannerlove@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
---
 tools/testing/selftests/bpf/progs/bpf_flow.c  | 187 +++++++++++++-----
 .../selftests/bpf/test_flow_dissector.c       | 181 ++++++++++++++---
 .../selftests/bpf/test_flow_dissector.sh      |  19 ++
 3 files changed, 321 insertions(+), 66 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/bpf_flow.c b/tools/testing/selftests/bpf/progs/bpf_flow.c
index 95a5a0778ed7..29af96dd63e4 100644
--- a/tools/testing/selftests/bpf/progs/bpf_flow.c
+++ b/tools/testing/selftests/bpf/progs/bpf_flow.c
@@ -13,6 +13,7 @@
 #include <linux/tcp.h>
 #include <linux/udp.h>
 #include <linux/if_packet.h>
+#include <linux/virtio_net.h>
 #include <sys/socket.h>
 #include <linux/if_tunnel.h>
 #include <linux/mpls.h>
@@ -71,15 +72,120 @@ struct {
 	__type(value, struct bpf_flow_keys);
 } last_dissection SEC(".maps");
 
-static __always_inline int export_flow_keys(struct bpf_flow_keys *keys,
+/* Drops invalid virtio-net headers */
+static __always_inline int validate_virtio_net_hdr(const struct __sk_buff *skb)
+{
+	const struct bpf_flow_keys *keys = skb->flow_keys;
+
+	/* Check gso */
+	if (skb->vhdr_gso_type != VIRTIO_NET_HDR_GSO_NONE) {
+		if (!(skb->vhdr_flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
+			return BPF_DROP;
+
+		if (keys->is_encap)
+			return BPF_DROP;
+
+		switch (skb->vhdr_gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
+		case VIRTIO_NET_HDR_GSO_TCPV4:
+			if (keys->addr_proto != ETH_P_IP ||
+			    keys->ip_proto != IPPROTO_TCP)
+				return BPF_DROP;
+
+			if (skb->vhdr_gso_size >= skb->len - keys->thoff -
+					sizeof(struct tcphdr))
+				return BPF_DROP;
+
+			break;
+		case VIRTIO_NET_HDR_GSO_TCPV6:
+			if (keys->addr_proto != ETH_P_IPV6 ||
+			    keys->ip_proto != IPPROTO_TCP)
+				return BPF_DROP;
+
+			if (skb->vhdr_gso_size >= skb->len - keys->thoff -
+					sizeof(struct tcphdr))
+				return BPF_DROP;
+
+			break;
+		case VIRTIO_NET_HDR_GSO_UDP:
+			if (keys->ip_proto != IPPROTO_UDP)
+				return BPF_DROP;
+
+			if (skb->vhdr_gso_size >= skb->len - keys->thoff -
+					sizeof(struct udphdr))
+				return BPF_DROP;
+
+			break;
+		default:
+			return BPF_DROP;
+		}
+	}
+
+	/* Check hdr_len */
+	if (skb->vhdr_hdr_len) {
+		switch (keys->ip_proto) {
+		case IPPROTO_TCP:
+			if (skb->vhdr_hdr_len != skb->flow_keys->thoff +
+					sizeof(struct tcphdr))
+				return BPF_DROP;
+
+			break;
+		case IPPROTO_UDP:
+			if (skb->vhdr_hdr_len != keys->thoff +
+					sizeof(struct udphdr))
+				return BPF_DROP;
+
+			break;
+		}
+	}
+
+	/* Check csum */
+	if (skb->vhdr_flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
+		if (keys->addr_proto != ETH_P_IP &&
+		    keys->addr_proto != ETH_P_IPV6)
+			return BPF_DROP;
+
+		if (skb->vhdr_csum_start != keys->thoff)
+			return BPF_DROP;
+
+		switch (keys->ip_proto) {
+		case IPPROTO_TCP:
+			if (skb->vhdr_csum_offset !=
+					offsetof(struct tcphdr, check))
+				return BPF_DROP;
+
+			break;
+		case IPPROTO_UDP:
+			if (skb->vhdr_csum_offset !=
+					offsetof(struct udphdr, check))
+				return BPF_DROP;
+
+			break;
+		default:
+			return BPF_DROP;
+		}
+	}
+
+	return BPF_OK;
+}
+
+/* Common steps to perform regardless of where protocol parsing finishes:
+ * 1. store flow keys in map
+ * 2. if parse result is BPF_OK, parse the vnet hdr if present
+ * 3. return the parse result
+ */
+static __always_inline int parse_epilogue(struct __sk_buff *skb,
 					    int ret)
 {
+	const struct bpf_flow_keys *keys = skb->flow_keys;
 	__u32 key = (__u32)(keys->sport) << 16 | keys->dport;
 	struct bpf_flow_keys val;
 
 	memcpy(&val, keys, sizeof(val));
 	bpf_map_update_elem(&last_dissection, &key, &val, BPF_ANY);
-	return ret;
+
+	if (ret != BPF_OK)
+		return ret;
+	return validate_virtio_net_hdr(skb);
 }
 
 #define IPV6_FLOWLABEL_MASK		__bpf_constant_htonl(0x000FFFFF)
@@ -114,8 +220,6 @@ static __always_inline void *bpf_flow_dissect_get_header(struct __sk_buff *skb,
 /* Dispatches on ETHERTYPE */
 static __always_inline int parse_eth_proto(struct __sk_buff *skb, __be16 proto)
 {
-	struct bpf_flow_keys *keys = skb->flow_keys;
-
 	switch (proto) {
 	case bpf_htons(ETH_P_IP):
 		bpf_tail_call_static(skb, &jmp_table, IP);
@@ -131,12 +235,10 @@ static __always_inline int parse_eth_proto(struct __sk_buff *skb, __be16 proto)
 	case bpf_htons(ETH_P_8021AD):
 		bpf_tail_call_static(skb, &jmp_table, VLAN);
 		break;
-	default:
-		/* Protocol not supported */
-		return export_flow_keys(keys, BPF_DROP);
 	}
 
-	return export_flow_keys(keys, BPF_DROP);
+	/* Protocol not supported */
+	return parse_epilogue(skb, BPF_DROP);
 }
 
 SEC("flow_dissector")
@@ -162,28 +264,28 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
 	case IPPROTO_ICMP:
 		icmp = bpf_flow_dissect_get_header(skb, sizeof(*icmp), &_icmp);
 		if (!icmp)
-			return export_flow_keys(keys, BPF_DROP);
-		return export_flow_keys(keys, BPF_OK);
+			return parse_epilogue(skb, BPF_DROP);
+		return parse_epilogue(skb, BPF_OK);
 	case IPPROTO_IPIP:
 		keys->is_encap = true;
 		if (keys->flags & BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP)
-			return export_flow_keys(keys, BPF_OK);
+			return parse_epilogue(skb, BPF_OK);
 
 		return parse_eth_proto(skb, bpf_htons(ETH_P_IP));
 	case IPPROTO_IPV6:
 		keys->is_encap = true;
 		if (keys->flags & BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP)
-			return export_flow_keys(keys, BPF_OK);
+			return parse_epilogue(skb, BPF_OK);
 
 		return parse_eth_proto(skb, bpf_htons(ETH_P_IPV6));
 	case IPPROTO_GRE:
 		gre = bpf_flow_dissect_get_header(skb, sizeof(*gre), &_gre);
 		if (!gre)
-			return export_flow_keys(keys, BPF_DROP);
+			return parse_epilogue(skb, BPF_DROP);
 
 		if (bpf_htons(gre->flags & GRE_VERSION))
 			/* Only inspect standard GRE packets with version 0 */
-			return export_flow_keys(keys, BPF_OK);
+			return parse_epilogue(skb, BPF_OK);
 
 		keys->thoff += sizeof(*gre); /* Step over GRE Flags and Proto */
 		if (GRE_IS_CSUM(gre->flags))
@@ -195,13 +297,13 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
 
 		keys->is_encap = true;
 		if (keys->flags & BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP)
-			return export_flow_keys(keys, BPF_OK);
+			return parse_epilogue(skb, BPF_OK);
 
 		if (gre->proto == bpf_htons(ETH_P_TEB)) {
 			eth = bpf_flow_dissect_get_header(skb, sizeof(*eth),
 							  &_eth);
 			if (!eth)
-				return export_flow_keys(keys, BPF_DROP);
+				return parse_epilogue(skb, BPF_DROP);
 
 			keys->thoff += sizeof(*eth);
 
@@ -212,37 +314,35 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
 	case IPPROTO_TCP:
 		tcp = bpf_flow_dissect_get_header(skb, sizeof(*tcp), &_tcp);
 		if (!tcp)
-			return export_flow_keys(keys, BPF_DROP);
+			return parse_epilogue(skb, BPF_DROP);
 
 		if (tcp->doff < 5)
-			return export_flow_keys(keys, BPF_DROP);
+			return parse_epilogue(skb, BPF_DROP);
 
 		if ((__u8 *)tcp + (tcp->doff << 2) > data_end)
-			return export_flow_keys(keys, BPF_DROP);
+			return parse_epilogue(skb, BPF_DROP);
 
 		keys->sport = tcp->source;
 		keys->dport = tcp->dest;
-		return export_flow_keys(keys, BPF_OK);
+		return parse_epilogue(skb, BPF_OK);
 	case IPPROTO_UDP:
 	case IPPROTO_UDPLITE:
 		udp = bpf_flow_dissect_get_header(skb, sizeof(*udp), &_udp);
 		if (!udp)
-			return export_flow_keys(keys, BPF_DROP);
+			return parse_epilogue(skb, BPF_DROP);
 
 		keys->sport = udp->source;
 		keys->dport = udp->dest;
-		return export_flow_keys(keys, BPF_OK);
+		return parse_epilogue(skb, BPF_OK);
 	default:
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 	}
 
-	return export_flow_keys(keys, BPF_DROP);
+	return parse_epilogue(skb, BPF_DROP);
 }
 
 static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
 {
-	struct bpf_flow_keys *keys = skb->flow_keys;
-
 	switch (nexthdr) {
 	case IPPROTO_HOPOPTS:
 	case IPPROTO_DSTOPTS:
@@ -255,7 +355,7 @@ static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
 		return parse_ip_proto(skb, nexthdr);
 	}
 
-	return export_flow_keys(keys, BPF_DROP);
+	return parse_epilogue(skb, BPF_DROP);
 }
 
 PROG(IP)(struct __sk_buff *skb)
@@ -268,11 +368,11 @@ PROG(IP)(struct __sk_buff *skb)
 
 	iph = bpf_flow_dissect_get_header(skb, sizeof(*iph), &_iph);
 	if (!iph)
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
 	/* IP header cannot be smaller than 20 bytes */
 	if (iph->ihl < 5)
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
 	keys->addr_proto = ETH_P_IP;
 	keys->ipv4_src = iph->saddr;
@@ -281,7 +381,7 @@ PROG(IP)(struct __sk_buff *skb)
 
 	keys->thoff += iph->ihl << 2;
 	if (data + keys->thoff > data_end)
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
 	if (iph->frag_off & bpf_htons(IP_MF | IP_OFFSET)) {
 		keys->is_frag = true;
@@ -302,7 +402,7 @@ PROG(IP)(struct __sk_buff *skb)
 	}
 
 	if (done)
-		return export_flow_keys(keys, BPF_OK);
+		return parse_epilogue(skb, BPF_OK);
 
 	return parse_ip_proto(skb, iph->protocol);
 }
@@ -314,7 +414,7 @@ PROG(IPV6)(struct __sk_buff *skb)
 
 	ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
 	if (!ip6h)
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
 	keys->addr_proto = ETH_P_IPV6;
 	memcpy(&keys->ipv6_src, &ip6h->saddr, 2*sizeof(ip6h->saddr));
@@ -324,7 +424,7 @@ PROG(IPV6)(struct __sk_buff *skb)
 	keys->flow_label = ip6_flowlabel(ip6h);
 
 	if (keys->flags & BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL)
-		return export_flow_keys(keys, BPF_OK);
+		return parse_epilogue(skb, BPF_OK);
 
 	return parse_ipv6_proto(skb, ip6h->nexthdr);
 }
@@ -336,7 +436,7 @@ PROG(IPV6OP)(struct __sk_buff *skb)
 
 	ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
 	if (!ip6h)
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
 	/* hlen is in 8-octets and does not include the first 8 bytes
 	 * of the header
@@ -354,7 +454,7 @@ PROG(IPV6FR)(struct __sk_buff *skb)
 
 	fragh = bpf_flow_dissect_get_header(skb, sizeof(*fragh), &_fragh);
 	if (!fragh)
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
 	keys->thoff += sizeof(*fragh);
 	keys->is_frag = true;
@@ -367,9 +467,9 @@ PROG(IPV6FR)(struct __sk_buff *skb)
 		 * explicitly asked for.
 		 */
 		if (!(keys->flags & BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG))
-			return export_flow_keys(keys, BPF_OK);
+			return parse_epilogue(skb, BPF_OK);
 	} else {
-		return export_flow_keys(keys, BPF_OK);
+		return parse_epilogue(skb, BPF_OK);
 	}
 
 	return parse_ipv6_proto(skb, fragh->nexthdr);
@@ -377,14 +477,13 @@ PROG(IPV6FR)(struct __sk_buff *skb)
 
 PROG(MPLS)(struct __sk_buff *skb)
 {
-	struct bpf_flow_keys *keys = skb->flow_keys;
 	struct mpls_label *mpls, _mpls;
 
 	mpls = bpf_flow_dissect_get_header(skb, sizeof(*mpls), &_mpls);
 	if (!mpls)
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
-	return export_flow_keys(keys, BPF_OK);
+	return parse_epilogue(skb, BPF_OK);
 }
 
 PROG(VLAN)(struct __sk_buff *skb)
@@ -396,10 +495,10 @@ PROG(VLAN)(struct __sk_buff *skb)
 	if (keys->n_proto == bpf_htons(ETH_P_8021AD)) {
 		vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
 		if (!vlan)
-			return export_flow_keys(keys, BPF_DROP);
+			return parse_epilogue(skb, BPF_DROP);
 
 		if (vlan->h_vlan_encapsulated_proto != bpf_htons(ETH_P_8021Q))
-			return export_flow_keys(keys, BPF_DROP);
+			return parse_epilogue(skb, BPF_DROP);
 
 		keys->nhoff += sizeof(*vlan);
 		keys->thoff += sizeof(*vlan);
@@ -407,14 +506,14 @@ PROG(VLAN)(struct __sk_buff *skb)
 
 	vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
 	if (!vlan)
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
 	keys->nhoff += sizeof(*vlan);
 	keys->thoff += sizeof(*vlan);
 	/* Only allow 8021AD + 8021Q double tagging and no triple tagging.*/
 	if (vlan->h_vlan_encapsulated_proto == bpf_htons(ETH_P_8021AD) ||
 	    vlan->h_vlan_encapsulated_proto == bpf_htons(ETH_P_8021Q))
-		return export_flow_keys(keys, BPF_DROP);
+		return parse_epilogue(skb, BPF_DROP);
 
 	keys->n_proto = vlan->h_vlan_encapsulated_proto;
 	return parse_eth_proto(skb, vlan->h_vlan_encapsulated_proto);
diff --git a/tools/testing/selftests/bpf/test_flow_dissector.c b/tools/testing/selftests/bpf/test_flow_dissector.c
index 571cc076dd7d..aa80055a5518 100644
--- a/tools/testing/selftests/bpf/test_flow_dissector.c
+++ b/tools/testing/selftests/bpf/test_flow_dissector.c
@@ -17,6 +17,8 @@
 #include <linux/if_packet.h>
 #include <linux/if_ether.h>
 #include <linux/ipv6.h>
+#include <linux/virtio_net.h>
+#include <net/if.h>
 #include <netinet/ip.h>
 #include <netinet/in.h>
 #include <netinet/udp.h>
@@ -65,7 +67,8 @@ struct guehdr {
 static uint8_t	cfg_dsfield_inner;
 static uint8_t	cfg_dsfield_outer;
 static uint8_t	cfg_encap_proto;
-static bool	cfg_expect_failure = false;
+static bool	cfg_expect_norx;
+static bool	cfg_expect_snd_failure;
 static int	cfg_l3_extra = AF_UNSPEC;	/* optional SIT prefix */
 static int	cfg_l3_inner = AF_UNSPEC;
 static int	cfg_l3_outer = AF_UNSPEC;
@@ -77,8 +80,14 @@ static int	cfg_port_gue = 6080;
 static bool	cfg_only_rx;
 static bool	cfg_only_tx;
 static int	cfg_src_port = 9;
+static bool	cfg_tx_pf_packet;
+static bool	cfg_use_vnet;
+static bool	cfg_vnet_use_hdr_len_bad;
+static bool	cfg_vnet_use_gso;
+static bool	cfg_vnet_use_csum_off;
+static bool	cfg_partial_udp_hdr;
 
-static char	buf[ETH_DATA_LEN];
+static char	buf[ETH_MAX_MTU];
 
 #define INIT_ADDR4(name, addr4, port)				\
 	static struct sockaddr_in name = {			\
@@ -273,8 +282,48 @@ static int l3_length(int family)
 		return sizeof(struct ipv6hdr);
 }
 
+static int build_vnet_header(void *header, int il3_len)
+{
+	struct virtio_net_hdr *vh = header;
+
+	vh->hdr_len = ETH_HLEN + il3_len + sizeof(struct udphdr);
+
+	if (cfg_partial_udp_hdr) {
+		vh->hdr_len -= (sizeof(struct udphdr) >> 1);
+		return sizeof(*vh);
+	}
+
+	/* Alteration must increase hdr_len; if not, kernel overwrites it */
+	if (cfg_vnet_use_hdr_len_bad)
+		vh->hdr_len++;
+
+	if (cfg_vnet_use_csum_off) {
+		vh->flags |= VIRTIO_NET_HDR_F_NEEDS_CSUM;
+		vh->csum_start = ETH_HLEN + il3_len;
+		vh->csum_offset = __builtin_offsetof(struct udphdr, check);
+	}
+
+	if (cfg_vnet_use_gso) {
+		vh->gso_type = VIRTIO_NET_HDR_GSO_UDP;
+		vh->gso_size = ETH_DATA_LEN - il3_len;
+	}
+
+	return sizeof(*vh);
+}
+
+static int build_eth_header(void *header)
+{
+	struct ethhdr *eth = header;
+	uint16_t proto = cfg_l3_inner == PF_INET ? ETH_P_IP : ETH_P_IPV6;
+
+	eth->h_proto = htons(proto);
+
+	return ETH_HLEN;
+}
+
 static int build_packet(void)
 {
+	int l2_len = 0;
 	int ol3_len = 0, ol4_len = 0, il3_len = 0, il4_len = 0;
 	int el3_len = 0;
 
@@ -294,23 +343,29 @@ static int build_packet(void)
 	il3_len = l3_length(cfg_l3_inner);
 	il4_len = sizeof(struct udphdr);
 
-	if (el3_len + ol3_len + ol4_len + il3_len + il4_len + cfg_payload_len >=
-	    sizeof(buf))
+	if (cfg_use_vnet)
+		l2_len += build_vnet_header(buf, il3_len);
+	if (cfg_tx_pf_packet)
+		l2_len += build_eth_header(buf + l2_len);
+
+	if (l2_len + el3_len + ol3_len + ol4_len + il3_len + il4_len +
+	    cfg_payload_len >= sizeof(buf))
 		error(1, 0, "packet too large\n");
 
 	/*
 	 * Fill packet from inside out, to calculate correct checksums.
 	 * But create ip before udp headers, as udp uses ip for pseudo-sum.
 	 */
-	memset(buf + el3_len + ol3_len + ol4_len + il3_len + il4_len,
+	memset(buf + l2_len + el3_len + ol3_len + ol4_len + il3_len + il4_len,
 	       cfg_payload_char, cfg_payload_len);
 
 	/* add zero byte for udp csum padding */
-	buf[el3_len + ol3_len + ol4_len + il3_len + il4_len + cfg_payload_len] = 0;
+	buf[l2_len + el3_len + ol3_len + ol4_len + il3_len + il4_len +
+	    cfg_payload_len] = 0;
 
 	switch (cfg_l3_inner) {
 	case PF_INET:
-		build_ipv4_header(buf + el3_len + ol3_len + ol4_len,
+		build_ipv4_header(buf + l2_len + el3_len + ol3_len + ol4_len,
 				  IPPROTO_UDP,
 				  in_saddr4.sin_addr.s_addr,
 				  in_daddr4.sin_addr.s_addr,
@@ -318,7 +373,7 @@ static int build_packet(void)
 				  cfg_dsfield_inner);
 		break;
 	case PF_INET6:
-		build_ipv6_header(buf + el3_len + ol3_len + ol4_len,
+		build_ipv6_header(buf + l2_len + el3_len + ol3_len + ol4_len,
 				  IPPROTO_UDP,
 				  &in_saddr6, &in_daddr6,
 				  il4_len + cfg_payload_len,
@@ -326,22 +381,25 @@ static int build_packet(void)
 		break;
 	}
 
-	build_udp_header(buf + el3_len + ol3_len + ol4_len + il3_len,
+	build_udp_header(buf + l2_len + el3_len + ol3_len + ol4_len + il3_len,
 			 cfg_payload_len, CFG_PORT_INNER, cfg_l3_inner);
 
+	if (cfg_partial_udp_hdr)
+		return l2_len + il3_len + (il4_len >> 1);
+
 	if (!cfg_encap_proto)
-		return il3_len + il4_len + cfg_payload_len;
+		return l2_len + il3_len + il4_len + cfg_payload_len;
 
 	switch (cfg_l3_outer) {
 	case PF_INET:
-		build_ipv4_header(buf + el3_len, cfg_encap_proto,
+		build_ipv4_header(buf + l2_len + el3_len, cfg_encap_proto,
 				  out_saddr4.sin_addr.s_addr,
 				  out_daddr4.sin_addr.s_addr,
 				  ol4_len + il3_len + il4_len + cfg_payload_len,
 				  cfg_dsfield_outer);
 		break;
 	case PF_INET6:
-		build_ipv6_header(buf + el3_len, cfg_encap_proto,
+		build_ipv6_header(buf + l2_len + el3_len, cfg_encap_proto,
 				  &out_saddr6, &out_daddr6,
 				  ol4_len + il3_len + il4_len + cfg_payload_len,
 				  cfg_dsfield_outer);
@@ -350,17 +408,17 @@ static int build_packet(void)
 
 	switch (cfg_encap_proto) {
 	case IPPROTO_UDP:
-		build_gue_header(buf + el3_len + ol3_len + ol4_len -
+		build_gue_header(buf + l2_len + el3_len + ol3_len + ol4_len -
 				 sizeof(struct guehdr),
 				 cfg_l3_inner == PF_INET ? IPPROTO_IPIP
 							 : IPPROTO_IPV6);
-		build_udp_header(buf + el3_len + ol3_len,
+		build_udp_header(buf + l2_len + el3_len + ol3_len,
 				 sizeof(struct guehdr) + il3_len + il4_len +
 				 cfg_payload_len,
 				 cfg_port_gue, cfg_l3_outer);
 		break;
 	case IPPROTO_GRE:
-		build_gre_header(buf + el3_len + ol3_len,
+		build_gre_header(buf + l2_len + el3_len + ol3_len,
 				 cfg_l3_inner == PF_INET ? ETH_P_IP
 							 : ETH_P_IPV6);
 		break;
@@ -368,7 +426,7 @@ static int build_packet(void)
 
 	switch (cfg_l3_extra) {
 	case PF_INET:
-		build_ipv4_header(buf,
+		build_ipv4_header(buf + l2_len,
 				  cfg_l3_outer == PF_INET ? IPPROTO_IPIP
 							  : IPPROTO_IPV6,
 				  extra_saddr4.sin_addr.s_addr,
@@ -377,7 +435,7 @@ static int build_packet(void)
 				  cfg_payload_len, 0);
 		break;
 	case PF_INET6:
-		build_ipv6_header(buf,
+		build_ipv6_header(buf + l2_len,
 				  cfg_l3_outer == PF_INET ? IPPROTO_IPIP
 							  : IPPROTO_IPV6,
 				  &extra_saddr6, &extra_daddr6,
@@ -386,15 +444,46 @@ static int build_packet(void)
 		break;
 	}
 
-	return el3_len + ol3_len + ol4_len + il3_len + il4_len +
+	return l2_len + el3_len + ol3_len + ol4_len + il3_len + il4_len +
 	       cfg_payload_len;
 }
 
+static int setup_tx_pfpacket(void)
+{
+	struct sockaddr_ll laddr = {0};
+	const int one = 1;
+	uint16_t proto;
+	int fd;
+
+	fd = socket(PF_PACKET, SOCK_RAW, 0);
+	if (fd == -1)
+		error(1, errno, "socket tx");
+
+	if (cfg_use_vnet &&
+	    setsockopt(fd, SOL_PACKET, PACKET_VNET_HDR, &one, sizeof(one)))
+		error(1, errno, "setsockopt vnet");
+
+	proto = cfg_l3_inner == PF_INET ? ETH_P_IP : ETH_P_IPV6;
+	laddr.sll_family = AF_PACKET;
+	laddr.sll_protocol = htons(proto);
+	laddr.sll_ifindex = if_nametoindex("lo");
+	if (!laddr.sll_ifindex)
+		error(1, errno, "if_nametoindex");
+
+	if (bind(fd, (void *)&laddr, sizeof(laddr)))
+		error(1, errno, "bind");
+
+	return fd;
+}
+
 /* sender transmits encapsulated over RAW or unencap'd over UDP */
 static int setup_tx(void)
 {
 	int family, fd, ret;
 
+	if (cfg_tx_pf_packet)
+		return setup_tx_pfpacket();
+
 	if (cfg_l3_extra)
 		family = cfg_l3_extra;
 	else if (cfg_l3_outer)
@@ -464,6 +553,13 @@ static int do_tx(int fd, const char *pkt, int len)
 	int ret;
 
 	ret = write(fd, pkt, len);
+
+	if (cfg_expect_snd_failure) {
+		if (ret == -1)
+			return 0;
+		error(1, 0, "expected tx to fail but it did not");
+	}
+
 	if (ret == -1)
 		error(1, errno, "send");
 	if (ret != len)
@@ -571,7 +667,7 @@ static int do_main(void)
 	 * success (== 0) only if received all packets
 	 * unless failure is expected, in which case none must arrive.
 	 */
-	if (cfg_expect_failure)
+	if (cfg_expect_norx || cfg_expect_snd_failure)
 		return rx != 0;
 	else
 		return rx != tx;
@@ -623,8 +719,12 @@ static void parse_opts(int argc, char **argv)
 {
 	int c;
 
-	while ((c = getopt(argc, argv, "d:D:e:f:Fhi:l:n:o:O:Rs:S:t:Tx:X:")) != -1) {
+	while ((c = getopt(argc, argv,
+			   "cd:D:e:Ef:FGghi:l:Ln:o:O:pRs:S:t:TUvx:X:")) != -1) {
 		switch (c) {
+		case 'c':
+			cfg_vnet_use_csum_off = true;
+			break;
 		case 'd':
 			if (cfg_l3_outer == AF_UNSPEC)
 				error(1, 0, "-d must be preceded by -o");
@@ -653,11 +753,17 @@ static void parse_opts(int argc, char **argv)
 			else
 				usage(argv[0]);
 			break;
+		case 'E':
+			cfg_expect_snd_failure = true;
+			break;
 		case 'f':
 			cfg_src_port = strtol(optarg, NULL, 0);
 			break;
 		case 'F':
-			cfg_expect_failure = true;
+			cfg_expect_norx = true;
+			break;
+		case 'g':
+			cfg_vnet_use_gso = true;
 			break;
 		case 'h':
 			usage(argv[0]);
@@ -673,6 +779,9 @@ static void parse_opts(int argc, char **argv)
 		case 'l':
 			cfg_payload_len = strtol(optarg, NULL, 0);
 			break;
+		case 'L':
+			cfg_vnet_use_hdr_len_bad = true;
+			break;
 		case 'n':
 			cfg_num_pkt = strtol(optarg, NULL, 0);
 			break;
@@ -682,6 +791,9 @@ static void parse_opts(int argc, char **argv)
 		case 'O':
 			cfg_l3_extra = parse_protocol_family(argv[0], optarg);
 			break;
+		case 'p':
+			cfg_tx_pf_packet = true;
+			break;
 		case 'R':
 			cfg_only_rx = true;
 			break;
@@ -703,6 +815,12 @@ static void parse_opts(int argc, char **argv)
 		case 'T':
 			cfg_only_tx = true;
 			break;
+		case 'U':
+			cfg_partial_udp_hdr = true;
+			break;
+		case 'v':
+			cfg_use_vnet = true;
+			break;
 		case 'x':
 			cfg_dsfield_outer = strtol(optarg, NULL, 0);
 			break;
@@ -733,7 +851,26 @@ static void parse_opts(int argc, char **argv)
 	 */
 	if (((cfg_dsfield_outer & 0x3) == 0x3) &&
 	    ((cfg_dsfield_inner & 0x3) == 0x0))
-		cfg_expect_failure = true;
+		cfg_expect_norx = true;
+
+	/* Don't wait around for packets that we expect to fail to send */
+	if (cfg_expect_snd_failure && !cfg_num_secs)
+		cfg_num_secs = 3;
+
+	if (cfg_partial_udp_hdr && cfg_encap_proto)
+		error(1, 0,
+		      "ops: can't specify partial UDP hdr (-U) and encap (-e)");
+
+	if (cfg_use_vnet && cfg_encap_proto)
+		error(1, 0, "options: cannot specify encap (-e) with vnet (-v)");
+	if (cfg_use_vnet && !cfg_tx_pf_packet)
+		error(1, 0, "options: vnet (-v) requires psock for tx (-p)");
+	if (cfg_vnet_use_gso && !cfg_use_vnet)
+		error(1, 0, "options: gso (-g) requires vnet (-v)");
+	if (cfg_vnet_use_csum_off && !cfg_use_vnet)
+		error(1, 0, "options: vnet csum (-c) requires vnet (-v)");
+	if (cfg_vnet_use_hdr_len_bad && !cfg_use_vnet)
+		error(1, 0, "options: bad vnet hdrlen (-L) requires vnet (-v)");
 }
 
 static void print_opts(void)
diff --git a/tools/testing/selftests/bpf/test_flow_dissector.sh b/tools/testing/selftests/bpf/test_flow_dissector.sh
index 174b72a64a4c..5852cf815eeb 100755
--- a/tools/testing/selftests/bpf/test_flow_dissector.sh
+++ b/tools/testing/selftests/bpf/test_flow_dissector.sh
@@ -51,6 +51,9 @@ if [[ -z $(ip netns identify $$) ]]; then
 		echo "Skipping root flow dissector test, bpftool not found" >&2
 	fi
 
+	orig_flow_dissect_sysctl=$(</proc/sys/net/core/flow_dissect_vnet_hdr)
+	sysctl net.core.flow_dissect_vnet_hdr=1
+
 	# Run the rest of the tests in a net namespace.
 	../net/in_netns.sh "$0" "$@"
 	err=$(( $err + $? ))
@@ -61,6 +64,7 @@ if [[ -z $(ip netns identify $$) ]]; then
 		echo "selftests: $TESTNAME [FAILED]";
 	fi
 
+	sysctl net.core.flow_dissect_vnet_hdr=$orig_flow_dissect_sysctl
 	exit $err
 fi
 
@@ -165,4 +169,19 @@ tc filter add dev lo parent ffff: protocol ipv6 pref 1337 flower ip_proto \
 # Send 10 IPv6/UDP packets from port 10. Filter should not drop any.
 ./test_flow_dissector -i 6 -f 10
 
+
+echo "Testing virtio-net header validation..."
+echo "Testing valid vnet headers. Should *not* be dropped."
+./with_addr.sh ./test_flow_dissector -i 4 -D 192.168.0.1 -S 1.1.1.1 -p -v
+echo "Testing partial transport header. Should be dropped."
+./with_addr.sh ./test_flow_dissector -i 4 -D 192.168.0.1 -S 1.1.1.1 -p -v -U -E
+echo "Testing valid vnet gso spec. Should *not* be dropped."
+./with_addr.sh ./test_flow_dissector -i 4 -D 192.168.0.1 -S 1.1.1.1 -p -v -g -c -l 8000
+echo "Testing invalid vnet gso size. Should be dropped."
+./with_addr.sh ./test_flow_dissector -i 4 -D 192.168.0.1 -S 1.1.1.1 -p -v -g -c -l 100 -E
+echo "Testing invalid vnet header len. Should be dropped."
+./with_addr.sh ./test_flow_dissector -i 4 -D 192.168.0.1 -S 1.1.1.1 -p -v -L -E
+echo "Testing vnet gso without csum. Should be dropped."
+./with_addr.sh ./test_flow_dissector -i 4 -D 192.168.0.1 -S 1.1.1.1 -p -v -g -l 8000 -E
+
 exit 0
-- 
2.32.0.rc0.204.g9fa02ecfa5-goog

Re: [PATCH net-next 1/3] net: flow_dissector: extend bpf flow dissector support with vnet hdr

[Jakub Kicinski]

On Thu, 27 May 2021 17:12:12 -0400 Tanner Love wrote:
> @@ -915,7 +916,8 @@ bool __skb_flow_dissect(const struct net *net,
>  			const struct sk_buff *skb,
>  			struct flow_dissector *flow_dissector,
>  			void *target_container, const void *data,
> -			__be16 proto, int nhoff, int hlen, unsigned int flags)
> +			__be16 proto, int nhoff, int hlen, unsigned int flags,
> +			const struct virtio_net_hdr *vhdr)
>  {
>  	struct flow_dissector_key_control *key_control;
>  	struct flow_dissector_key_basic *key_basic;

net/core/flow_dissector.c:922: warning: Function parameter or member 'vhdr' not described in '__skb_flow_dissect'

Please try to check W=1 C=1 builds, you may want to compile only the
object files you changed otherwise for a change like this, touching
skbuff.h, you'll drown in old warnings.