On Tue, Aug 30, 2016 at 7:56 PM, Serge E. Hallyn <serge@xxxxxxxxxx> wrote:
> On Fri, Aug 26, 2016 at 04:08:08PM -0700, Andrei Vagin wrote:
>> +struct ns_common *ns_get_owner(struct ns_common *ns)
>> +{
>> + struct user_namespace *my_user_ns = current_user_ns();
>> + struct user_namespace *owner, *p;
>> +
>> + /* See if the owner is in the current user namespace */
>> + owner = p = ns->ops->get_owner(ns);
>> + for (;;) {
>> + if (!p)
>> + return ERR_PTR(-EPERM);
>> + if (p == my_user_ns)
>> + break;
>> + p = p->parent;
>> + }
>> +
>> + return &get_user_ns(owner)->ns;
>
> get_user_ns() bumps the owner's refcount. I don't see where
> this is being dropped, especially when ns_ioctl() uses it in
> the next patch.
It is dropped in __ns_get_path if a namespace has a dentry, otherwise
it is dropped from nsfs_evict.
static void *__ns_get_path(struct path *path, struct ns_common *ns)
| return -EPERM;
...
ns->ops->put(ns); |
got_it:
| /* See if the owner is in the current user namespace
*/
path->mnt = mnt;
| owner = p = ns->ops->get_owner(ns);
path->dentry = dentry;
| for (;;) {
return NULL;
...
static void nsfs_evict(struct inode *inode) |
{
| if (!ns_capable(user_ns, CAP_SYS_ADMIN))
struct ns_common *ns = inode->i_private;
| return -EPERM;
clear_inode(inode); |
ns->ops->put(ns);
| cred = prepare_creds();
}
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