Andrei Vagin <avagin@xxxxxxxxx> writes:
> On Thu, Jul 21, 2016 at 9:40 AM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>> index 2c2eb1b629b1..a489f192d619 100644
>> --- a/net/core/net_namespace.c
>> +++ b/net/core/net_namespace.c
>> @@ -266,6 +266,16 @@ struct net *get_net_ns_by_id(struct net *net, int id)
>> return peer;
>> }
>>
>> +static bool inc_net_namespaces(struct user_namespace *ns)
>> +{
>> + return inc_ucount(ns, UCOUNT_NET_NAMESPACES);
>> +}
>> +
>> +static void dec_net_namespaces(struct user_namespace *ns)
>> +{
>> + dec_ucount(ns, UCOUNT_NET_NAMESPACES);
>> +}
>> +
>> /*
>> * setup_net runs the initializers for the network namespace object.
>> */
>> @@ -276,6 +286,9 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
>> int error = 0;
>> LIST_HEAD(net_exit_list);
>>
>> + if (!inc_net_namespaces(user_ns))
>> + return -ENFILE;
>
> I think you need to move this check after initilizing net->passive.
> When setup_net returns an error, net_drop_ns is called:
>
Good point. Ouch!
> void net_drop_ns(void *p)
> {
> struct net *ns = p;
> if (ns && atomic_dec_and_test(&ns->passive))
> net_free(ns);
> }
>
> Actually, I think it would be better to make this check before
> net_alloc().
You are probably right. I seem to be trying to be entirely too clever
putting that in setup_net so I can cover the initial network namespace.
Which really does not need to be counted. As clearly I also goofed up
the decrement on error case as well.
Eric
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