[lxc-devel] [PATCH 1/1] Fix bug in preserve_ns

[Stéphane Graber]

On Fri, Jan 10, 2014 at 09:48:30PM -0600, Serge Hallyn wrote:
> If /proc/self/ns does not exist, then preserve_ns was failing to
> initialize the saved_ns[i] to -1.  This caused attach_ns() to try
> and attach, and of course fail.
> 
> Initialize the saved ns values before returning an error.
> 
> The return values of preserve_ns and attach_ns were also being
> ignored.  Honor them.
> 
> Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>

Acked-by: Stéphane Graber <stgraber at ubuntu.com>

> ---
>  src/lxc/start.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/src/lxc/start.c b/src/lxc/start.c
> index ce88d5f..6c07e43 100644
> --- a/src/lxc/start.c
> +++ b/src/lxc/start.c
> @@ -98,14 +98,14 @@ static int preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags) {
>  	int i, saved_errno;
>  	char path[MAXPATHLEN];
>  
> -	if (access("/proc/self/ns", X_OK)) {
> -		ERROR("Does this kernel version support 'attach'?");
> -		return -1;
> -	}
> -
>  	for (i = 0; i < LXC_NS_MAX; i++)
>  		ns_fd[i] = -1;
>  
> +	if (access("/proc/self/ns", X_OK)) {
> +		WARN("Kernel does not support attach; preserve_ns ignored");
> +		return 0;
> +	}
> +
>  	for (i = 0; i < LXC_NS_MAX; i++) {
>  		if ((clone_flags & ns_info[i].clone_flag) == 0)
>  			continue;
> @@ -788,8 +788,10 @@ static int lxc_spawn(struct lxc_handler *handler)
>  	if (handler->pinfd == -1)
>  		INFO("failed to pin the container's rootfs");
>  
> -	preserve_ns(saved_ns_fd, preserve_mask);
> -	attach_ns(handler->conf->inherit_ns_fd);
> +	if (preserve_ns(saved_ns_fd, preserve_mask) < 0)
> +		goto out_delete_net;
> +	if (attach_ns(handler->conf->inherit_ns_fd) < 0)
> +		goto out_delete_net;
>  
>  	/* Create a process in a new set of namespaces */
>  	handler->pid = lxc_clone(do_start, handler, handler->clone_flags);
> @@ -798,7 +800,8 @@ static int lxc_spawn(struct lxc_handler *handler)
>  		goto out_delete_net;
>  	}
>  
> -	attach_ns(saved_ns_fd);
> +	if (attach_ns(saved_ns_fd))
> +		WARN("failed to restore saved namespaces");
>  
>  	lxc_sync_fini_child(handler);
>  
> -- 
> 1.8.5.2
> 
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel

-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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