Re: [PATCH v1] Bluetooth: Enforce key size of 16 bytes on FIPS level

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

Hi Archie,

On Mon, Sep 21, 2020 at 1:31 AM Archie Pusaka <apusaka@google.com> wrote:
>
> From: Archie Pusaka <apusaka@chromium.org>
>
> According to the spec Ver 5.2, Vol 3, Part C, Sec 5.2.2.8:
> Device in security mode 4 level 4 shall enforce:
> 128-bit equivalent strength for link and encryption keys required
> using FIPS approved algorithms (E0 not allowed, SAFER+ not allowed,
> and P-192 not allowed; encryption key not shortened)
>
> This patch rejects connection with key size below 16 for FIPS level
> services.
>
> Signed-off-by: Archie Pusaka <apusaka@chromium.org>
> Reviewed-by: Alain Michaud <alainm@chromium.org>
>
> ---
>
>  net/bluetooth/l2cap_core.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index ade83e224567..306616ec26e6 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -1515,8 +1515,13 @@ static bool l2cap_check_enc_key_size(struct hci_conn *hcon)
>          * that have no key size requirements. Ensure that the link is
>          * actually encrypted before enforcing a key size.
>          */
> +       int min_key_size = hcon->hdev->min_enc_key_size;
> +
> +       if (hcon->sec_level == BT_SECURITY_FIPS)
> +               min_key_size = 16;
> +
>         return (!test_bit(HCI_CONN_ENCRYPT, &hcon->flags) ||
> -               hcon->enc_key_size >= hcon->hdev->min_enc_key_size);
> +               hcon->enc_key_size >= min_key_size);

While this looks fine to me, it looks like this should be placed
elsewhere since it takes an hci_conn and it is not L2CAP specific.

>  }
>
>  static void l2cap_do_start(struct l2cap_chan *chan)
> --
> 2.28.0.681.g6f77f65b4e-goog
>


-- 
Luiz Augusto von Dentz