[CRIU] [PATCH v3 25/33] user_ns: Set user_ns before net_ns creation

[Kirill Tkhai]

On 21.02.2017 10:34, Andrei Vagin wrote:
> On Thu, Feb 16, 2017 at 03:10:14PM +0300, Kirill Tkhai wrote:
>> Since net ns may reffer not only to root_user_ns,
>> set appropriate user_ns before its creation.
> 
> We need a test for this case

There is unshare(CLONE_NEWNET) in userns00.
 
>>
>> v3: New
>>
>> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
>> ---
>>  criu/net.c |   43 +++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 43 insertions(+)
>>
>> diff --git a/criu/net.c b/criu/net.c
>> index 200199822..fb4d9f84d 100644
>> --- a/criu/net.c
>> +++ b/criu/net.c
>> @@ -1721,9 +1721,39 @@ static int open_net_ns(struct ns_id *nsid, struct rst_info *rst)
>>  	return 0;
>>  }
>>  
>> +static int create_net_ns(void *arg)
>> +{
>> +	struct ns_id *uns, *ns = arg;
>> +	int ufd;
>> +
>> +	uns = ns->user_ns;
>> +	ufd = fdstore_get(uns->user.nsfd_id);
>> +	if (ufd < 0) {
>> +		pr_err("Can't get user ns\n");
>> +		exit(1);
>> +	}
>> +	if (setns(ufd, CLONE_NEWUSER) < 0) {
>> +		pr_perror("Can't set user ns");
>> +		exit(2);
>> +	}
> 
> should we set a proper uid here?

I haven't seen, unshare() requires uid in additional to capabilities. What are you implying?
 
>> +	close(ufd);
>> +	if (unshare(CLONE_NEWNET)) {
>> +		pr_perror("Unable to create a new netns");
>> +		exit(3);
>> +	}
>> +	if (prepare_net_ns(ns->id))
>> +		exit(4);
>> +	if (open_net_ns(ns, rsti(root_item)))
>> +		exit(5);
>> +	exit(0);
>> +}
>> +
>>  int prepare_net_namespaces()
>>  {
>> +	char stack[128] __stack_aligned__;
>>  	struct ns_id *nsid;
>> +	int status;
>> +	pid_t pid;
>>  
>>  	if (!(root_ns_mask & CLONE_NEWNET))
>>  		return 0;
>> @@ -1732,6 +1762,19 @@ int prepare_net_namespaces()
>>  		if (nsid->nd != &net_ns_desc)
>>  			continue;
>>  
>> +		if (root_user_ns && nsid->user_ns != root_user_ns) {
>> +			pid = clone(create_net_ns, stack + 128, CLONE_NEWNET | SIGCHLD, nsid);
>> +			if (pid < 0) {
>> +				pr_perror("Can't clone");
>> +				goto err;
>> +			}
>> +			if (waitpid(pid, &status, 0) != pid || !WIFEXITED(status) || WEXITSTATUS(status)) {
>> +				pr_perror("Child process waiting %d", status);
>> +				goto err;
>> +			}
>> +			continue;
>> +		}
>> +
>>  		if (unshare(CLONE_NEWNET)) {
>>  			pr_perror("Unable to create a new netns");
>>  			goto err;
>>
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