[lxc-devel] [PATCH] c/r: remember to chown the cgroup path (correctly)

[Serge Hallyn]

Quoting Tycho Andersen (tycho.andersen at canonical.com):
> 1. remember to chown the cgroup path when migrating a container
> 2. when restoring the cgroup path, try to compute the euid for root vs.
>    using geteuid(); geteuid works for start, but it doesn't work for
>    migration since we're still real root at that point.
> 
> Signed-off-by: Tycho Andersen <tycho.andersen at canonical.com>
> ---
>  src/lxc/cgmanager.c | 6 +++++-
>  src/lxc/criu.c      | 5 +++++
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/src/lxc/cgmanager.c b/src/lxc/cgmanager.c
> index 357182a..54e6912 100644
> --- a/src/lxc/cgmanager.c
> +++ b/src/lxc/cgmanager.c
> @@ -488,7 +488,11 @@ static bool chown_cgroup(const char *cgroup_path, struct lxc_conf *conf)
>  		return true;
>  
>  	data.cgroup_path = cgroup_path;
> -	data.origuid = geteuid();
> +	data.origuid = mapped_hostid(0, conf, ID_TYPE_UID);
> +	if (data.origuid < 0) {

Can you confirm that this does not break

sudo lxc-create -t download -n x1 -- -d ubuntu -r trusty -a amd64
sudo lxc-start -n x1

Because in that case I think we have no mappings, and mapped_hostid() will
return -1.

> +		ERROR("failed to get mapped root id");
> +		return false;
> +	}
>  
>  	/* Unpriv users can't chown it themselves, so chown from
>  	 * a child namespace mapping both our own and the target uid
> diff --git a/src/lxc/criu.c b/src/lxc/criu.c
> index 6ef4905..f442612 100644
> --- a/src/lxc/criu.c
> +++ b/src/lxc/criu.c
> @@ -466,6 +466,11 @@ void do_restore(struct lxc_container *c, int pipe, char *directory, bool verbose
>  		goto out_fini_handler;
>  	}
>  
> +	if (!cgroup_chown(handler)) {
> +		ERROR("failed creating groups");
> +		goto out_fini_handler;
> +	}
> +
>  	if (!restore_net_info(c)) {
>  		ERROR("failed restoring network info");
>  		goto out_fini_handler;
> -- 
> 2.6.4
> 
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