check whether /sys/fs/cgroup is a mountpoint

The current check only tries to detect whether /sys/fs/cgroup exists and
whether it is writable or not. But when the init system doesn't mount
cgroups then /sys/fs/cgroup will just be an empty directory. When paired
with unprivileged containers that mount sysfs this will cause misleading
errors to be printed since /sys/fs/cgroup will be owned by user
nobody:nogroup in this case. Independent of this specific problem this
check will also be misleading when the /sys/fs/cgroup exists and is in
fact writable by the init system but isn't actually a mountpoint.

Note from William. "grep -qs" doesn't need to redirect output to
/dev/null since it is completely silent.

This fixes #209.
This commit is contained in:
Christian Brauner 2018-02-12 13:32:01 +01:00 committed by William Hubbs
parent 38032626a6
commit 16ff3cd8df

View File

@ -259,11 +259,14 @@ for _cmd; do
ulimit ${rc_ulimit:-$RC_ULIMIT}
# Apply cgroups settings if defined
if [ "$(command -v cgroup_add_service)" = "cgroup_add_service" ]
then
if grep -qs /sys/fs/cgroup /proc/1/mountinfo
then
if [ -d /sys/fs/cgroup -a ! -w /sys/fs/cgroup ]; then
eerror "No permission to apply cgroup settings"
break
fi
fi
cgroup_add_service
fi
[ "$(command -v cgroup_set_limits)" = "cgroup_set_limits" ] &&