[CRIU] [PATCH v3 05/33] ns: Set nested namespaces hookups

[Kirill Tkhai]

On 22.02.2017 07:43, Andrei Vagin wrote:
> On Tue, Feb 21, 2017 at 02:53:38PM +0300, Kirill Tkhai wrote:
>> On 21.02.2017 08:45, Andrei Vagin wrote:
>>> On Thu, Feb 16, 2017 at 03:07:19PM +0300, Kirill Tkhai wrote:
>>>> Introduce ns_id::parent and assign a pointer to parent
>>>> for every ns except NS_CRIU and NS_ROOT.
>>>> Also populate user_ns for pid_ns.
>>>>
>>>> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
>>>> ---
>>>>  criu/include/namespaces.h |   12 ++++++
>>>>  criu/namespaces.c         |   87 +++++++++++++++++++++++++++++++++++++++++++++
>>>>  2 files changed, 99 insertions(+)
>>>>
>>>> diff --git a/criu/include/namespaces.h b/criu/include/namespaces.h
>>>> index 1b454e0c1..69df0313b 100644
>>>> --- a/criu/include/namespaces.h
>>>> +++ b/criu/include/namespaces.h
>>>> @@ -1,6 +1,8 @@
>>>>  #ifndef __CR_NS_H__
>>>>  #define __CR_NS_H__
>>>>  
>>>> +#include <sys/ioctl.h>
>>>> +
>>>>  #include "common/compiler.h"
>>>>  #include "files.h"
>>>>  #include "common/list.h"
>>>> @@ -40,6 +42,12 @@
>>>>  
>>>>  #define EXTRA_SIZE	20
>>>>  
>>>> +#ifndef NSIO
>>>> +#define NSIO    0xb7
>>>> +#define NS_GET_USERNS   _IO(NSIO, 0x1)
>>>> +#define NS_GET_PARENT   _IO(NSIO, 0x2)
>>>> +#endif
>>>> +
>>>>  struct ns_desc {
>>>>  	unsigned int	cflag;
>>>>  	char		*str;
>>>> @@ -76,6 +84,10 @@ struct ns_id {
>>>>  	unsigned int id;
>>>>  	pid_t ns_pid;
>>>>  	struct ns_desc *nd;
>>>> +	struct ns_id *parent;
>>>> +	struct list_head children;
>>>> +	struct list_head siblings;
>>>> +	struct ns_id *user_ns;
>>>>  	struct ns_id *next;
>>>>  	enum ns_type type;
>>>>  
>>>> diff --git a/criu/namespaces.c b/criu/namespaces.c
>>>> index 9e61c9481..c4ef52733 100644
>>>> --- a/criu/namespaces.c
>>>> +++ b/criu/namespaces.c
>>>> @@ -13,6 +13,7 @@
>>>>  #include <sys/stat.h>
>>>>  #include <limits.h>
>>>>  #include <errno.h>
>>>> +#include <sys/ioctl.h>
>>>>  
>>>>  #include "page.h"
>>>>  #include "rst-malloc.h"
>>>> @@ -302,6 +303,8 @@ struct ns_id *rst_new_ns_id(unsigned int id, pid_t pid,
>>>>  		nsid->type = type;
>>>>  		nsid_add(nsid, nd, id, pid);
>>>>  		nsid->ns_populated = false;
>>>> +		INIT_LIST_HEAD(&nsid->children);
>>>> +		INIT_LIST_HEAD(&nsid->siblings);
>>>>  	}
>>>>  
>>>>  	return nsid;
>>>> @@ -421,6 +424,8 @@ static unsigned int generate_ns_id(int pid, unsigned int kid, struct ns_desc *nd
>>>>  	nsid->type = type;
>>>>  	nsid->kid = kid;
>>>>  	nsid->ns_populated = true;
>>>> +	INIT_LIST_HEAD(&nsid->children);
>>>> +	INIT_LIST_HEAD(&nsid->siblings);
>>>>  	nsid_add(nsid, nd, ns_next_id++, pid);
>>>>  
>>>>  found:
>>>> @@ -661,6 +666,88 @@ int dump_task_ns_ids(struct pstree_item *item)
>>>>  	return 0;
>>>>  }
>>>>  
>>>> +static int set_ns_opt(int ns_fd, unsigned ioc, struct ns_id **ns, struct ns_desc *nd)
>>>> +{
>>>> +	int opt_fd, ret = -1;
>>>> +	struct stat st;
>>>> +
>>>> +	opt_fd = ioctl(ns_fd, ioc);
>>>> +	if (opt_fd < 0) {
>>>> +		pr_info("Can't do ns ioctl %x\n", ioc);
>>>> +		return -errno;
>>>> +	}
>>>> +	if (fstat(opt_fd, &st) < 0) {
>>>> +		pr_perror("Unable to stat on ns fd");
>>>> +		ret = -errno;
>>>> +		goto out;
>>>> +	}
>>>> +	*ns = lookup_ns_by_kid(st.st_ino, nd);
>>>> +	if (!*ns) {
>>>> +		pr_err("Namespaces hierarhies with holes are not supported\n");
>>>> +		ret = -EINVAL;
>>>> +		goto out;
>>>> +	}
>>>> +	ret = 0;
>>>> +out:
>>>> +	close(opt_fd);
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int set_ns_hookups(struct ns_id *ns)
>>>> +{
>>>> +	struct ns_desc *nd = ns->nd;
>>>> +	struct ns_id *u_ns;
>>>> +	int fd, ret = -1;
>>>> +
>>>> +	fd = open_proc(ns->ns_pid, "ns/%s", nd->str);
>>>> +	if (fd < 0) {
>>>> +		pr_perror("Can't open %s, pid %d", nd->str, ns->ns_pid);
>>>> +		return -1;
>>>> +	}
>>>> +
>>>> +	if (ns->type != NS_ROOT && (nd == &pid_ns_desc || nd == &user_ns_desc)) {
>>>> +		if (set_ns_opt(fd, NS_GET_PARENT, &ns->parent, nd) < 0)
>>>> +			goto out;
>>>> +		if (ns->parent && ns->parent->type == NS_CRIU) {
>>>> +			pr_err("Wrong determined NS_ROOT, or root_item has NS_OTHER user_ns\n");
>>>> +			goto out;
>>>> +		}
>>>> +		list_add(&ns->siblings, &ns->parent->children);
>>>> +	}
>>>> +
>>>> +	if (nd != &user_ns_desc) {
>>>> +		ret = set_ns_opt(fd, NS_GET_USERNS, &ns->user_ns, &user_ns_desc);
>>>> +		if (ret == -ENOTTY) {
>>>> +			pr_info("Can't get user_ns of %s %u, assuming NS_ROOT\n",
>>>> +					nd->str, ns->id);
>>>
>>> It is possible only if we dump only one userns.
>>
>> Sure, and if we have several user_ns, we'll fail on NS_GET_PARENT made for one of them.
> 
> pls, add a comment here about this.

OK

>>
>>>> +			u_ns = NULL;
>>>> +			if (root_ns_mask & CLONE_NEWUSER) {
>>>> +				for (u_ns = ns_ids; u_ns; u_ns = u_ns->next) {
>>>> +					if (u_ns->nd == &user_ns_desc && u_ns->type == NS_ROOT)
>>>> +						break;
>>>> +				}
>>>> +				if (!u_ns) {
>>>> +					pr_err("Can't find root user_ns\n");
>>>> +					goto out;
>>>> +				}
>>>> +			}
>>>> +			ns->user_ns = u_ns;
>>>> +		} else if (ret < 0) {
>>>> +			goto out;
>>>> +		} else if (ns->user_ns->type == NS_CRIU) {
>>>> +			if (root_ns_mask & CLONE_NEWUSER) {
>>>> +				pr_err("Must not be criu user_ns\n");
>>>
>>> ret is zero here
>>
>> Yeah, I'll fix that.
>>
>>>
>>>> +				goto out;
>>>> +			}
>>>> +			ns->user_ns = NULL;
>>>> +		}
>>>> +	}
>>>> +	ret = 0;
>>>> +out:
>>>> +	close(fd);
>>>> +	return ret;
>>>> +}
>>>> +
>>>>  static UsernsEntry userns_entry = USERNS_ENTRY__INIT;
>>>>  #define INVALID_ID (~0U)
>>>>  
>>>>
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