[bpf-next,v8,09/18] xdp: Add VLAN tag hint

Commit Message

Larysa Zaremba Dec. 5, 2023, 9:08 p.m. UTC

Implement functionality that enables drivers to expose VLAN tag
to XDP code.

VLAN tag is represented by 2 variables:
- protocol ID, which is passed to bpf code in BE
- VLAN TCI, in host byte order

Acked-by: Stanislav Fomichev <[e-mail]>
Signed-off-by: Larysa Zaremba <[e-mail]>
---
 Documentation/netlink/specs/netdev.yaml      |  4 +++
 Documentation/networking/xdp-rx-metadata.rst |  8 ++++-
 include/net/xdp.h                            |  6 ++++
 include/uapi/linux/netdev.h                  |  3 ++
 net/core/xdp.c                               | 33 ++++++++++++++++++++
 tools/include/uapi/linux/netdev.h            |  3 ++
 tools/net/ynl/generated/netdev-user.c        |  1 +
 7 files changed, 57 insertions(+), 1 deletion(-)

Comments

Jesper Dangaard Brouer Dec. 6, 2023, 8:25 a.m. UTC | #1

On 12/5/23 22:08, Larysa Zaremba wrote:
> Implement functionality that enables drivers to expose VLAN tag
> to XDP code.
> 
> VLAN tag is represented by 2 variables:
> - protocol ID, which is passed to bpf code in BE
> - VLAN TCI, in host byte order
> 
> Acked-by: Stanislav Fomichev <[e-mail]>
> Signed-off-by: Larysa Zaremba <[e-mail]>
> ---

Small doc nitpicks below, but it can go in-as-is

Acked-by: Jesper Dangaard Brouer <[e-mail]>

>   Documentation/netlink/specs/netdev.yaml      |  4 +++
>   Documentation/networking/xdp-rx-metadata.rst |  8 ++++-
>   include/net/xdp.h                            |  6 ++++
>   include/uapi/linux/netdev.h                  |  3 ++
>   net/core/xdp.c                               | 33 ++++++++++++++++++++
>   tools/include/uapi/linux/netdev.h            |  3 ++
>   tools/net/ynl/generated/netdev-user.c        |  1 +
>   7 files changed, 57 insertions(+), 1 deletion(-)
[...]

> diff --git a/net/core/xdp.c b/net/core/xdp.c
> index b6f1d6dab3f2..4869c1c2d8f3 100644
> --- a/net/core/xdp.c
> +++ b/net/core/xdp.c
> @@ -736,6 +736,39 @@ __bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, u32 *hash,
>   	return -EOPNOTSUPP;
>   }
>   
> +/**
> + * bpf_xdp_metadata_rx_vlan_tag - Get XDP packet outermost VLAN tag
> + * @ctx: XDP context pointer.
> + * @vlan_proto: Destination pointer for VLAN Tag protocol identifier (TPID).

I would have written: Tag Protocol Identifier (TPID).
  - like e.g. CCNA exam https://study-ccna.com/ieee-802-1q/

Capital letters leading up to the short version, but I don't think this
is a requirement. I noticed that wikipedia also got this wrong. So, I it
doesn't really matter. If you need to do a respin, I would appreciate
this changed, but you got my ACK anyway.

> + * @vlan_tci: Destination pointer for VLAN TCI (VID + DEI + PCP)
> + *
> + * In case of success, ``vlan_proto`` contains *Tag protocol identifier (TPID)*,
> + * usually ``ETH_P_8021Q`` or ``ETH_P_8021AD``, but some networks can use
> + * custom TPIDs. ``vlan_proto`` is stored in **network byte order (BE)**
> + * and should be used as follows:
> + * ``if (vlan_proto == bpf_htons(ETH_P_8021Q)) do_something();``
> + *
> + * ``vlan_tci`` contains the remaining 16 bits of a VLAN tag.
> + * Driver is expected to provide those in **host byte order (usually LE)**,
> + * so the bpf program should not perform byte conversion.
> + * According to 802.1Q standard, *VLAN TCI (Tag control information)*
> + * is a bit field that contains:
> + * *VLAN identifier (VID)* that can be read with ``vlan_tci & 0xfff``,
> + * *Drop eligible indicator (DEI)* - 1 bit,

Drop Eligible Indicator (DEI)

> + * *Priority code point (PCP)* - 3 bits.

Priority Code Point (PCP)

> + * For detailed meaning of DEI and PCP, please refer to other sources.
> + *
> + * Return:
> + * * Returns 0 on success or ``-errno`` on error.
> + * * ``-EOPNOTSUPP`` : device driver doesn't implement kfunc
> + * * ``-ENODATA``    : VLAN tag was not stripped or is not available
> + */
> +__bpf_kfunc int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx,
> +					     __be16 *vlan_proto, u16 *vlan_tci)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
>   __bpf_kfunc_end_defs();

Patch

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index eef6358ec587..aeec090e1387 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -54,6 +54,10 @@  definitions:
         name: hash
         doc:
           Device is capable of exposing receive packet hash via bpf_xdp_metadata_rx_hash().
+      -
+        name: vlan-tag
+        doc:
+          Device is capable of exposing receive packet VLAN tag via bpf_xdp_metadata_rx_vlan_tag().
   -
     type: flags
     name: xsk-flags
diff --git a/Documentation/networking/xdp-rx-metadata.rst b/Documentation/networking/xdp-rx-metadata.rst
index e3e9420fd817..a6e0ece18be5 100644
--- a/Documentation/networking/xdp-rx-metadata.rst
+++ b/Documentation/networking/xdp-rx-metadata.rst
@@ -20,7 +20,13 @@  Currently, the following kfuncs are supported. In the future, as more
 metadata is supported, this set will grow:
 
 .. kernel-doc:: net/core/xdp.c
-   :identifiers: bpf_xdp_metadata_rx_timestamp bpf_xdp_metadata_rx_hash
+   :identifiers: bpf_xdp_metadata_rx_timestamp
+
+.. kernel-doc:: net/core/xdp.c
+   :identifiers: bpf_xdp_metadata_rx_hash
+
+.. kernel-doc:: net/core/xdp.c
+   :identifiers: bpf_xdp_metadata_rx_vlan_tag
 
 An XDP program can use these kfuncs to read the metadata into stack
 variables for its own consumption. Or, to pass the metadata on to other
diff --git a/include/net/xdp.h b/include/net/xdp.h
index eb77040b4825..ef79f124dbcf 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -399,6 +399,10 @@  void xdp_attachment_setup(struct xdp_attachment_info *info,
 			   NETDEV_XDP_RX_METADATA_HASH, \
 			   bpf_xdp_metadata_rx_hash, \
 			   xmo_rx_hash) \
+	XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_VLAN_TAG, \
+			   NETDEV_XDP_RX_METADATA_VLAN_TAG, \
+			   bpf_xdp_metadata_rx_vlan_tag, \
+			   xmo_rx_vlan_tag) \
 
 enum xdp_rx_metadata {
 #define XDP_METADATA_KFUNC(name, _, __, ___) name,
@@ -460,6 +464,8 @@  struct xdp_metadata_ops {
 	int	(*xmo_rx_timestamp)(const struct xdp_md *ctx, u64 *timestamp);
 	int	(*xmo_rx_hash)(const struct xdp_md *ctx, u32 *hash,
 			       enum xdp_rss_hash_type *rss_type);
+	int	(*xmo_rx_vlan_tag)(const struct xdp_md *ctx, __be16 *vlan_proto,
+				   u16 *vlan_tci);
 };
 
 #ifdef CONFIG_NET
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index 6244c0164976..966638b08ccf 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -44,10 +44,13 @@  enum netdev_xdp_act {
  *   timestamp via bpf_xdp_metadata_rx_timestamp().
  * @NETDEV_XDP_RX_METADATA_HASH: Device is capable of exposing receive packet
  *   hash via bpf_xdp_metadata_rx_hash().
+ * @NETDEV_XDP_RX_METADATA_VLAN_TAG: Device is capable of exposing receive
+ *   packet VLAN tag via bpf_xdp_metadata_rx_vlan_tag().
  */
 enum netdev_xdp_rx_metadata {
 	NETDEV_XDP_RX_METADATA_TIMESTAMP = 1,
 	NETDEV_XDP_RX_METADATA_HASH = 2,
+	NETDEV_XDP_RX_METADATA_VLAN_TAG = 4,
 };
 
 /**
diff --git a/net/core/xdp.c b/net/core/xdp.c
index b6f1d6dab3f2..4869c1c2d8f3 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -736,6 +736,39 @@  __bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, u32 *hash,
 	return -EOPNOTSUPP;
 }
 
+/**
+ * bpf_xdp_metadata_rx_vlan_tag - Get XDP packet outermost VLAN tag
+ * @ctx: XDP context pointer.
+ * @vlan_proto: Destination pointer for VLAN Tag protocol identifier (TPID).
+ * @vlan_tci: Destination pointer for VLAN TCI (VID + DEI + PCP)
+ *
+ * In case of success, ``vlan_proto`` contains *Tag protocol identifier (TPID)*,
+ * usually ``ETH_P_8021Q`` or ``ETH_P_8021AD``, but some networks can use
+ * custom TPIDs. ``vlan_proto`` is stored in **network byte order (BE)**
+ * and should be used as follows:
+ * ``if (vlan_proto == bpf_htons(ETH_P_8021Q)) do_something();``
+ *
+ * ``vlan_tci`` contains the remaining 16 bits of a VLAN tag.
+ * Driver is expected to provide those in **host byte order (usually LE)**,
+ * so the bpf program should not perform byte conversion.
+ * According to 802.1Q standard, *VLAN TCI (Tag control information)*
+ * is a bit field that contains:
+ * *VLAN identifier (VID)* that can be read with ``vlan_tci & 0xfff``,
+ * *Drop eligible indicator (DEI)* - 1 bit,
+ * *Priority code point (PCP)* - 3 bits.
+ * For detailed meaning of DEI and PCP, please refer to other sources.
+ *
+ * Return:
+ * * Returns 0 on success or ``-errno`` on error.
+ * * ``-EOPNOTSUPP`` : device driver doesn't implement kfunc
+ * * ``-ENODATA``    : VLAN tag was not stripped or is not available
+ */
+__bpf_kfunc int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx,
+					     __be16 *vlan_proto, u16 *vlan_tci)
+{
+	return -EOPNOTSUPP;
+}
+
 __bpf_kfunc_end_defs();
 
 BTF_SET8_START(xdp_metadata_kfunc_ids)
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index 6244c0164976..966638b08ccf 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -44,10 +44,13 @@  enum netdev_xdp_act {
  *   timestamp via bpf_xdp_metadata_rx_timestamp().
  * @NETDEV_XDP_RX_METADATA_HASH: Device is capable of exposing receive packet
  *   hash via bpf_xdp_metadata_rx_hash().
+ * @NETDEV_XDP_RX_METADATA_VLAN_TAG: Device is capable of exposing receive
+ *   packet VLAN tag via bpf_xdp_metadata_rx_vlan_tag().
  */
 enum netdev_xdp_rx_metadata {
 	NETDEV_XDP_RX_METADATA_TIMESTAMP = 1,
 	NETDEV_XDP_RX_METADATA_HASH = 2,
+	NETDEV_XDP_RX_METADATA_VLAN_TAG = 4,
 };
 
 /**
diff --git a/tools/net/ynl/generated/netdev-user.c b/tools/net/ynl/generated/netdev-user.c
index 3b9dee94d4ce..e3fe748086bd 100644
--- a/tools/net/ynl/generated/netdev-user.c
+++ b/tools/net/ynl/generated/netdev-user.c
@@ -53,6 +53,7 @@  const char *netdev_xdp_act_str(enum netdev_xdp_act value)
 static const char * const netdev_xdp_rx_metadata_strmap[] = {
 	[0] = "timestamp",
 	[1] = "hash",
+	[2] = "vlan-tag",
 };
 
 const char *netdev_xdp_rx_metadata_str(enum netdev_xdp_rx_metadata value)