[lxc-users] lxc.mount.entry selectively mount parts of sys and proc read write

[Serge Hallyn]

Quoting GC (catchall at gc9.org):
> Hello,
> 
> I want to selectively mount parts of sys and proc rw, but the rest
> ro.  I thought I might be able to e.g., mount /sys ro (in the
> container), and mount /.sys rw (in the container), then bind mount
> bits from /.sys to /sys, and finally hide the rw /.sys by mounting
> another directory on top of it, like:
> 
> lxc.mount.entry = sysfs sys sysfs ro 0 0
> lxc.mount.entry = sysfs .sys sysfs rw 0 0        # (dot)sys
> 
> lxc.mount.entry = /var/lib/lxc/container/.sys/module/ipv6
> sys/module/ipv6 none defaults,bind 0 0
> # or alternatively (also doesn't work) this instead of line above
> #lxc.mount.entry = .sys/module/ipv6 sys/module/ipv6 none defaults,bind 0 0
> 
> lxc.mount.entry = /var/lib/lxc/dummy_mount .sys none ro,bind 0 0
> 
> 
> The part where I try to perform the bind mount of the read/write
> .sys/module/ipv6 (in the container) on top of the read only
> sys/module/ipv6  (in the container) fails.  Is there  a way to get
> this to work?

Wouldn't it be simpler to simply bind mount /sys ro from the host,
then bind-mount /sys/module/ipv6 from the host rw into the container?

I assume your container won't have cap_sys_admin to prevent remounting?

-serge