[CRIU] [PATCH 4/5] ns: Fix wrong opened net ns file

[Andrei Vagin]

On Fri, Mar 24, 2017 at 12:35:11PM +0300, Kirill Tkhai wrote:
> Since net ns is assigned after prepare_fds() and,
> in common case, at the moment of open_ns_fd() call
> task points to a net ns, which differs to its target
> net ns, we can't get the ns from a task. So, get it
> from fdstore. Also, support userns ns fds.
> 
> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
> ---
>  criu/namespaces.c |   21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/criu/namespaces.c b/criu/namespaces.c
> index e4555251..ee309045 100644
> --- a/criu/namespaces.c
> +++ b/criu/namespaces.c
> @@ -556,8 +556,22 @@ static int open_ns_fd(struct file_desc *d, int *new_fd)
>  	struct ns_file_info *nfi = container_of(d, struct ns_file_info, d);
>  	struct pstree_item *item, *t;
>  	struct ns_desc *nd = NULL;
> +	struct ns_id *ns;
> +	int nsfd_id, fd;
>  	char path[64];
> -	int fd;
> +
> +	for (ns = ns_ids; ns != NULL; ns = ns->next) {
> +		if (ns->id != nfi->nfe->ns_id)
> +			continue;
> +		if (ns->nd == &user_ns_desc && (root_ns_mask & CLONE_NEWUSER))
> +			nsfd_id = ns->user.nsfd_id;
> +		else if (ns->nd == &net_ns_desc && (root_ns_mask & CLONE_NEWNET))
> +			nsfd_id = ns->net.nsfd_id;
> +		else
> +			break;
> +		fd = fdstore_get(nsfd_id);
> +		goto check_open;
> +	}
>  
>  	/*
>  	 * Find out who can open us.
> @@ -575,6 +589,10 @@ static int open_ns_fd(struct file_desc *d, int *new_fd)
>  			item = t;
>  			nd = &net_ns_desc;
>  			break;
> +		} else if (ids->user_ns_id == nfi->nfe->ns_id) {
> +			item = t;
> +			nd = &user_ns_desc;
> +			break;

hm, why do we need this code here? The first loop has to handle them,
doesn't it?

>  		} else if (ids->ipc_ns_id == nfi->nfe->ns_id) {
>  			item = t;
>  			nd = &ipc_ns_desc;
> @@ -608,6 +626,7 @@ static int open_ns_fd(struct file_desc *d, int *new_fd)
>  	path[sizeof(path) - 1] = '\0';
>  
>  	fd = open(path, nfi->nfe->flags);
> +check_open:
>  	if (fd < 0) {
>  		pr_perror("Can't open file %s on restore", path);
>  		return fd;
>