Comment 0 for bug 1860969

[SRU Justification]

[Impact]

Packets sent to a vti[6]/xfrm interface via bpf_redirect() or via an AF_PACKET socket are dropped (no carrier).

This has been fixed in v5.5 by the following upstream commits
 - 95224166a903 ("vti[6]: fix packet tx through bpf_redirect()")
 - f042365dbffe ("xfrm interface: fix packet tx through bpf_redirect()")

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=95224166a903
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f042365dbffe

The bug exists since the beginning of each driver.

== Fix ==

Backport the requested patches to Focal (5.4), Disco (5.0), Bionic (4.15) and
Xenial (4.4).

== Risk of Regression ==

This patch affects only the cases described above (when no dst is attached to the skb), thus the risk should be low.