[CRIU] [PATCH 2/3] ns: Set NS_ROOT namespaces after tasks are read

[Andrei Vagin]

On Tue, Feb 28, 2017 at 04:41:52PM +0300, Kirill Tkhai wrote:
> Namespaces are read in read_ns_with_hookups(),
> when tasks are not read. So, root_item is NULL,
> and NS_ROOT is not set for appropriate namespaces.
> 
> This patch fixes NS_ROOT after tasks are read. Also
> it adds uts, ipc and cgroup namespaces for uniformity.
> 
> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
> ---
>  criu/include/namespaces.h |    1 +
>  criu/namespaces.c         |   33 +++++++++++++++++++++++++++++----
>  criu/pstree.c             |   17 +++++++++++++++++
>  3 files changed, 47 insertions(+), 4 deletions(-)
> 
> diff --git a/criu/include/namespaces.h b/criu/include/namespaces.h
> index 2a3dc085b..05c08b52e 100644
> --- a/criu/include/namespaces.h
> +++ b/criu/include/namespaces.h
> @@ -149,6 +149,7 @@ extern int collect_mnt_namespaces(bool for_dump);
>  extern int dump_mnt_namespaces(void);
>  extern int dump_namespaces(struct pstree_item *item, unsigned int ns_flags);
>  extern int read_ns_with_hookups(void);
> +extern int set_ns_roots(void);
>  extern int prepare_namespace_before_tasks(void);
>  extern int prepare_namespace(struct pstree_item *item, unsigned long clone_flags);
>  
> diff --git a/criu/namespaces.c b/criu/namespaces.c
> index b1e65df43..a92477df0 100644
> --- a/criu/namespaces.c
> +++ b/criu/namespaces.c
> @@ -315,7 +315,6 @@ struct ns_id *rst_new_ns_id(unsigned int id, pid_t pid,
>  int rst_add_ns_id(unsigned int id, struct pstree_item *i, struct ns_desc *nd)
>  {
>  	pid_t pid = vpid(i);
> -	int type = NS_OTHER;
>  	struct ns_id *nsid;
>  
>  	nsid = lookup_ns_by_id(id, nd);
> @@ -325,9 +324,7 @@ int rst_add_ns_id(unsigned int id, struct pstree_item *i, struct ns_desc *nd)
>  		return 0;
>  	}

Can we remove the hack with the fake pstree_entry?

        pid.ns[0].virt = -1;
        fake.pid = &pid;

....
	if (rst_add_ns_id(e->id, &fake, desc)) {
		pr_err("Can't add user ns\n");
		goto close;
	}

Can we call rst_new_ns_id instead of rst_add_ns_id in read_ns_with_hookups()?


>  
> -	if (i == root_item && nd != &user_ns_desc)
> -		type = NS_ROOT;
> -	nsid = rst_new_ns_id(id, pid, nd, type);
> +	nsid = rst_new_ns_id(id, pid, nd, NS_OTHER);
>  	if (nsid == NULL)
>  		return -1;
>  
> @@ -1985,6 +1982,34 @@ int read_ns_with_hookups(void)
>  	return ret;
>  }
>  
> +static int mark_root_ns(uint32_t id, struct ns_desc *desc)
> +{
> +	struct ns_id *ns;
> +
> +	ns = lookup_ns_by_id(id, desc);
> +	if (!ns) {
> +		pr_err("Can't find root ns %u, %s\n", id, desc->str);
> +		return -1;
> +	}
> +	ns->type = NS_ROOT;
> +	return 0;
> +}
> +
> +int set_ns_roots(void)
> +{
> +	TaskKobjIdsEntry *ids = root_item->ids;
> +
> +	/* Set root for all namespaces except user_ns, which is set in read_ns_with_hookups() */
> +	if ((ids->has_pid_ns_id && mark_root_ns(ids->pid_ns_id, &pid_ns_desc) < 0) ||
> +	    (ids->has_net_ns_id && mark_root_ns(ids->net_ns_id, &net_ns_desc) < 0) ||
> +	    (ids->has_ipc_ns_id && mark_root_ns(ids->ipc_ns_id, &ipc_ns_desc) < 0) ||
> +	    (ids->has_uts_ns_id && mark_root_ns(ids->uts_ns_id, &uts_ns_desc) < 0) ||
> +	    (ids->has_mnt_ns_id && mark_root_ns(ids->mnt_ns_id, &mnt_ns_desc) < 0) ||
> +	    (ids->has_cgroup_ns_id && mark_root_ns(ids->cgroup_ns_id, &cgroup_ns_desc) < 0))

maybe we can add a marcos to make this code readable

	MARK_ROOT_NS(mnt);
	MARK_ROOT_NS(ipc);
	...
> +		return -1;
> +	return 0;
> +}
> +
>  int prepare_userns(pid_t real_pid, UsernsEntry *e)
>  {
>  	if (write_id_map(real_pid, e->uid_map, e->n_uid_map, "uid_map"))
> diff --git a/criu/pstree.c b/criu/pstree.c
> index dd40fbcee..b497e1989 100644
> --- a/criu/pstree.c
> +++ b/criu/pstree.c
> @@ -9,6 +9,9 @@
>  #include "rst-malloc.h"
>  #include "common/lock.h"
>  #include "namespaces.h"
> +#include "cgroup.h"
> +#include "ipc_ns.h"
> +#include "uts_ns.h"
>  #include "files.h"
>  #include "tty.h"
>  #include "mount.h"
> @@ -488,6 +491,18 @@ static int read_pstree_ids(struct pstree_item *pi)
>  		if (rst_add_ns_id(pi->ids->pid_ns_id, pi, &pid_ns_desc))
>  			return -1;
>  	}
> +	if (pi->ids->has_ipc_ns_id) {
> +		if (rst_add_ns_id(pi->ids->ipc_ns_id, pi, &ipc_ns_desc))
> +			return -1;
> +	}
> +	if (pi->ids->has_uts_ns_id) {
> +		if (rst_add_ns_id(pi->ids->uts_ns_id, pi, &uts_ns_desc))
> +			return -1;
> +	}
> +	if (pi->ids->has_cgroup_ns_id) {
> +		if (rst_add_ns_id(pi->ids->cgroup_ns_id, pi, &cgroup_ns_desc))
> +			return -1;
> +	}
>  
>  	return 0;
>  }
> @@ -596,6 +611,8 @@ static int read_pstree_image(pid_t *pid_max)
>  			goto err;
>  	}
>  
> +	if (ret == 0)
> +		ret = set_ns_roots();
>  err:
>  	close_image(img);
>  	return ret;
>