net: tun: Enable transfer of XDP metadata to skb

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When the XDP metadata area was used, it is expected that the same
metadata can also be accessed from TC, as can be read in the description
of the bpf_xdp_adjust_meta helper function. In the tun driver, this was
not yet implemented.

To make this work, the skb that is being built on XDP_PASS should know
of the current size of the metadata area. This is ensured by adding
calls to skb_metadata_set. For the tun_xdp_one code path, an additional
check is necessary to handle the case where the externally initialized
xdp_buff has no metadata support (xdp->data_meta == xdp->data + 1).

More information about this feature can be found in the commit message
of commit de8f3a83b0 ("bpf: add meta pointer for direct access").

Signed-off-by: Marcus Wichelmann <marcus.wichelmann@hetzner-cloud.de>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20250305213438.3863922-3-marcus.wichelmann@hetzner-cloud.de

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Marcus Wichelmann 2025-03-05 21:34:34 +00:00 • committed by Martin KaFai Lau

parent c2315ebb05

commit 0ca23a4d64

1 changed files with 22 additions and 3 deletions

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drivers/net/tun.c

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