On Fri, 23 Sep 2011, Serge E. Hallyn wrote: > Quoting Alan Stern (stern@xxxxxxxxxxxxxxxxxxx): > > On Fri, 23 Sep 2011, Serge E. Hallyn wrote: > > > > > (re-sending to Cc: Greg and linux-usb) > > > > > > Add to the dev_state and alloc_async structures the user namespace > > > corresponding to the uid and euid. Pass these to kill_pid_info_as_uid(), > > > which can then implement a proper, user-namespace-aware uid check. > > > > > > Changelog: > > > Sep 20: Per Oleg's suggestion: Instead of caching and passing user namespace, > > > uid, and euid each separately, pass a struct cred. > > > > This should be broken up into two separate patches: One to add > > kill_pid_info_as_cred() and the other to modify the usbfs driver. > > It seems like that would make the first patch harder to review (since > it won't just show the changes from kill_pid_info_as_uid to > kill_pid_info_as_cred), but I'll go ahead and split it up. I assume > kill_pid_info_as_uid should be removed in a third patch? No, what I meant was that all the changes to /kernel/signal.c should be in one patch and all the changes to drivers/usb/core/devio.c should be in a second patch. You did check to make sure there are no other references to kill_pid_info_as_uid() in the kernel? > > > if (signr) > > > - kill_pid_info_as_uid(sinfo.si_signo, &sinfo, pid, uid, > > > - euid, secid); > > > + kill_pid_info_as_cred(sinfo.si_signo, &sinfo, pid, cred, secid); > > > > This continues a bug that already exists in the current code. Once > > ps->lock is released, there is no guarantee that the async structure > > will still exist. It may already have been freed, and the reference to > > Yikes. That makes sense. I'll fix that for the cred and the pid as well > then? Right. > > as->cred may already have been dropped. That's why the local copies > > have to be made above. cred shouldn't be a simple copy of as->cred; it > > should also increment the reference count. > > > > > @@ -706,8 +705,7 @@ static int usbdev_open(struct inode *inode, struct file *file) > > > init_waitqueue_head(&ps->wait); > > > ps->discsignr = 0; > > > ps->disc_pid = get_pid(task_pid(current)); > > > - ps->disc_uid = cred->uid; > > > - ps->disc_euid = cred->euid; > > > + ps->cred = get_cred(cred); > > > > You might as well get rid of the "cred" local variable. It isn't used > > for anything except this assignment. > > > > Alan Stern > > Thanks for looking, Alan. You're welcome. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
