[Lxc-users] Restoring a process fails under lxc 1.0.0.alpha1

[Frederico Araujo]

Hi,

I've been using checkpoint/restore (CRIU 0.7) under lxc containers on
Ubuntu Saucy for a while and everything was running smoothly until I
updated my lxc from version 0.9 to the new release (1.0.0.alpha1). After
the update, restoring even a simple program (no sockets, just a simple
infinite loop printing some text) returns:

"Error (cr-restore.c:894): 475: Can't open /proc/sys/kernel/ns_last_pid:
Permission denied"

My container was configured using the lxc template for Ubuntu, using the
default configuration. So, my question is: did the new version of lxc
changed anything related to access permission to the
/proc/sys/kernel/ns_last_pid file? I am running CRIU restore as root inside
the container. I made a small test running CRIU restore on the host machine
and it works fine; my best guess is that something has changed in the way
LXC handles the container's root permissions. If not, am I missing
something? Is there a way to allow a container root to open ns_last_pid
with R/W permissions from inside the container (I checked CRIU source code
and this is where it fails)?

I am running host and container on Ubuntu Saucy (3.11.0-7). Also, 'sysctl
kernel.ns_last_pid' works fine from inside the container.

Any help will be appreciated!
Thanks,
Fred
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