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SubjectRe: [Bluez PATCH v3] bluetooth: secure bluetooth stack from bluedump attack
Hi Howard,

On Wed, Feb 12, 2020 at 7:39 AM Johan Hedberg <johan.hedberg@gmail.com> wrote:
>
> Hi Marcel,
>
> On 12. Feb 2020, at 17.19, Marcel Holtmann <marcel@holtmann.org> wrote:
> >> + key = hci_find_ltk(hcon->hdev, &hcon->dst, hcon->dst_type,
> >> + hcon->role);
> >> +
> >> + /* If there already exists link key in local host, leave the
> >> + * decision to user space since the remote device could be
> >> + * legitimate or malicious.
> >> + */
> >> + if (smp->method == JUST_WORKS && key) {
> >> + err = mgmt_user_confirm_request(hcon->hdev, &hcon->dst,
> >> + hcon->type,
> >> + hcon->dst_type, passkey,
> >> + 1);
> >> + if (err)
> >> + return SMP_UNSPECIFIED;
> >> + set_bit(SMP_FLAG_WAIT_USER, &smp->flags);
> >> + }
> >> }
> >
> > while this looks good, I like to optimize this to only look up the LTK when needed.

I wonder why we don't just call user confirm everytime? That way the
new policy preference applies to both a new pair or when already
paired, and we don't have to really do the key lookup here since the
userspace can do the check if really needed.

> >
> > /* comment here */
> > if (smp->method != JUST_WORKS)
> > goto mackey_and_ltk;
> >
> >
> > /* and command here */
> > if (hci_find_ltk()) {
> > mgmt_user_confirm_request()
> > ..
> > }
> >
> > And my preference that we also get an Ack from Johan or Luiz that double checked that this is fine.
>
> Acked-by: Johan Hedberg <johan.hedberg@intel.com>
>
> Johan



--
Luiz Augusto von Dentz

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