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

[Kirill Tkhai]

On 27.03.2017 23:36, Andrei Vagin wrote:
> 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?

We do add net_ns and user_ns fds to fdstore only if we have
appropriate bit in root_ns_mask is set.
 
>>  		} 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;
>>