lkml.org 
[lkml]   [2022]   [May]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH 1/1] can: skb: add and set local_origin flag
    On Sat. 14 May 2022 at 12:29, Marc Kleine-Budde <mkl@pengutronix.de> wrote:
    > On 11.05.2022 15:24:21, Marc Kleine-Budde wrote:
    > > On 11.05.2022 14:38:32, Oliver Hartkopp wrote:
    > > > IMO this patch does not work as intended.
    > > >
    > > > You probably need to revisit every place where can_skb_reserve() is used,
    > > > e.g. in raw_sendmsg().
    > >
    > > And the loopback for devices that don't support IFF_ECHO:
    > >
    > > | https://elixir.bootlin.com/linux/latest/source/net/can/af_can.c#L257
    >
    > BTW: There is a bug with interfaces that don't support IFF_ECHO.
    >
    > Assume an invalid CAN frame is passed to can_send() on an interface that
    > doesn't support IFF_ECHO. The above mentioned code does happily generate
    > an echo frame and it's send, even if the driver drops it, due to
    > can_dropped_invalid_skb(dev, skb).
    >
    > The echoed back CAN frame is treated in raw_rcv() as if the headroom is valid:
    >
    > | https://elixir.bootlin.com/linux/v5.17.6/source/net/can/raw.c#L138
    >
    > But as far as I can see the can_skb_headroom_valid() check never has
    > been done. What about this patch?
    >
    > index 1fb49d51b25d..fda4807ad165 100644
    > --- a/net/can/af_can.c
    > +++ b/net/can/af_can.c
    > @@ -255,6 +255,9 @@ int can_send(struct sk_buff *skb, int loop)
    > */
    >
    > if (!(skb->dev->flags & IFF_ECHO)) {
    > + if (can_dropped_invalid_skb(dev, skb))
    > + return -EINVAL;
    > +

    This means that can_dropped_invalid_skb() would be called twice: one
    time in can_send() and one time in the driver's xmit() function,
    right?
    It would be nice to find a trick to detect whether the skb was
    injected through the packet socket or not in order not to execute
    can_dropped_invalid_skb() twice. I guess the information of the
    provenance of the skb is available somewhere, just not sure where (not
    familiar with the packet socket).


    Yours sincerely,
    Vincent Mailhol

    \
     
     \ /
      Last update: 2022-05-14 05:45    [W:4.237 / U:0.044 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site