[PATCH] Fix CVE-2020-15257

[PATCH] Fix CVE-2020-15257

This is the 1.2 backport. It's the Samuel Karp patch with additional changes:

 - Add ReadAddress function from commit 84a24711e88
 - Add "horten the unix socket path for shim" commit (a631796fda6)

Below is the original commit message:

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Use path based unix socket for shims

This allows filesystem based ACLs for configuring access to the socket of a
shim.

Co-authored-by: Samuel Karp <skarp@amazon.com>
Signed-off-by: Samuel Karp <skarp@amazon.com>
Signed-off-by: Michael Crosby <michael@thepasture.io>
Signed-off-by: Michael Crosby <michael.crosby@apple.com>
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containerd-shim: use path-based unix socket

This allows filesystem-based ACLs for configuring access to the socket
of a shim.

Ported from Michael Crosby's similar patch for v2 shims.

Signed-off-by: Samuel Karp <skarp@amazon.com>
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Co-authored-by: Paulo Flabiano Smorigo <pfsmorigo@canonical.com>
Co-authored-by: varsha teratipally <teratipally@google.com>
Signed-off-by: Tianon Gravi <tianon@infosiftr.com>
Gbp-Pq: Name cve-2020-15257.patch