On 03/21/2014 07:15 AM, Serge Hallyn wrote:
Quoting GC ([email protected]):
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 thought there would be issues with namespace support. I thought it
would break network namespaces, which appears to be wrong from your
comment. But, I also don't see how this can work with user namespaces,
since root in container will not be able to write to the host's /sys, if
it is bind mounted. I'm still trying to get a container to work with
user namespaces, so my assumption that writes will work to /sys, mounted
rw via lxc.mount.entry, is untested.
I assume your container won't have cap_sys_admin to prevent remounting?
Correct.
Thnx,
g
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