oci: use /proc/self/fd/FD to open unix socket

[giuseppe]

instead of opening directly the UNIX socket path, grab a reference to
it through a O_PATH file descriptor and use the fixed size string
"/proc/self/fd/%d" to open the UNIX socket. In this way it won't hit
the 108 chars length limit.

Closes: #8798

Signed-off-by: Giuseppe Scrivano [email protected]

[openshift-ci-robot]

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[rhatdan]

Cool idea, why is it draft?

[giuseppe]

Cool idea, why is it draft?

just to make sure it solves the reported issue before we merge

[rhatdan]

LGTM
@containers/podman-maintainers PTAL

[mheon]

Change LGTM, but I'd like verification from someone actually seeing the issue.

[haircommander]

if you run rootless with a UID > like 10000 you run into this issue pretty easily.

I have tested and it fixes the issue for me:

 $ sudo su - hello
Last login: Tue Jan  5 16:06:21 EST 2021 on pts/0
[hello@localhost ~]$ cd ../pehunt/go/src/github.com/containers/libpod/
[hello@localhost libpod]$ ./bin/podman run --rm -ti alpine 
ERRO[0000] The storage 'driver' option must be set in /etc/containers/storage.conf, guarantee proper operation. 
ERRO[0000] The storage 'driver' option must be set in /etc/containers/storage.conf, guarantee proper operation. 
WARN[0000] Failed to add podman to systemd sandbox cgroup: dial unix /run/user/0/bus: connect: permission denied 
/ # exit
[hello@localhost libpod]$ podman run --rm -ti alpine 
Error: failed to connect to container's attach socket: /tmp/run-205013812/libpod/tmp/socket/d023d0895bce04d8b00aa33fe85f96389b2024c8c76e3c88626661e97a6f88c8/attac: dial unixpacket /tmp/run-205013812/libpod/tmp/socket/d023d0895bce04d8b00aa33fe85f96389b2024c8c76e3c88626661e97a6f88c8/attac: connect: no such file or directory
[hello@localhost libpod]$ id
uid=205013812(hello) gid=1002(hello) groups=1002(hello) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
[hello@localhost libpod]$

where bin/podman is this fork

[rhatdan]

Ok we can merge once @giuseppe changes this to not draft and it actually passes the tests.

[giuseppe]

ready to merge!

[vrothberg]

LGTM

[rhatdan]

/lgtm
/hold

[vrothberg]

/hold cancel