On Fri, Apr 03, 2020 at 07:55:28PM +0200, Odin Ugedal wrote:

Original cgroup v2 eBPF code for filtering device access made it
possible to compile with CONFIG_CGROUP_DEVICE=n and still use the eBPF
filtering. Change 
commit 4b7d4d453fc4 ("device_cgroup: Export devcgroup_check_permission")
reverted this, making it required to set it to y.

Since the device filtering (and all the docs) for cgroup v2 is no longer
a "device controller" like it was in v1, someone might compile their
kernel with CONFIG_CGROUP_DEVICE=n. Then (for linux 5.5+) the eBPF
filter will not be invoked, and all processes will be allowed access
to all devices, no matter what the eBPF filter says.

Signed-off-by: Odin Ugedal <redacted>

Hello, Odin!

The patch makes perfect sense to me.

Acked-by: Roman Gushchin <redacted>

Thanks!