[CRIU] [PATCH v4 03/31] ns: Set nested namespaces hookups

[Kirill Tkhai]

On 23.02.2017 00:09, Andrei Vagin wrote:
> On Wed, Feb 22, 2017 at 02:30:51PM +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.
>>
>> v4: Set "ret = -1" on one of the error pathes.
>>     Add comment about user_ns finding.
>>
>> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
>> ---
>>  criu/include/namespaces.h |   12 ++++++
>>  criu/namespaces.c         |   92 +++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 104 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 b22162a3a..dd9fb7680 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 +666,93 @@ 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;
>> +		}
> 
> CID 176742:  Null pointer dereferences  (FORWARD_NULL)
> Comparing "ns->parent" to null implies that "ns->parent" might
> be null.

Ok, I'll just remove ns->parent check.
 
>> +		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) {
>> +			u_ns = NULL;
>> +			if (root_ns_mask & CLONE_NEWUSER) {
>> +				/*
>> +				 * Assume, we have the only user_ns. If it's not so,
>> +				 * we'll later fail on NS_GET_PARENT for the second user_ns.
>> +				 */
>> +				pr_info("Can't get user_ns of %s %u, assuming NS_ROOT\n",
>> +					nd->str, ns->id);
>> +				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 = -1;
>> +				goto out;
>> +			}
>> +			ns->user_ns = NULL;
>> +		}
>> +	}
>> +	ret = 0;
>> +out:
>> +	close(fd);
>> +	return ret;
>> +}
>> +
>>  static UsernsEntry userns_entry = USERNS_ENTRY__INIT;
>>  #define INVALID_ID (~0U)
>>  
>>