On 09/19/2017 07:42 AM, Mauro Carvalho Chehab wrote:
> Two readonly ioctls can't be allowed if the frontend device
> is opened in read only mode. Explain why.
>
> Signed-off-by: Mauro Carvalho Chehab
> ---
> drivers/media/dvb-core/dvb_frontend.c | 20 +---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/dvb-core/dvb_frontend.c
> b/drivers/media/dvb-core/dvb_frontend.c
> index d0a17d67ab1b..db3f8c597a24 100644
> --- a/drivers/media/dvb-core/dvb_frontend.c
> +++ b/drivers/media/dvb-core/dvb_frontend.c
> @@ -1940,9 +1940,23 @@ static int dvb_frontend_ioctl(struct file *file,
> unsigned int cmd, void *parg)
> return -ENODEV;
> }
>
> - if ((file->f_flags & O_ACCMODE) == O_RDONLY &&
> - (_IOC_DIR(cmd) != _IOC_READ || cmd == FE_GET_EVENT ||
> - cmd == FE_DISEQC_RECV_SLAVE_REPLY)) {
> + /*
> + * If the frontend is opened in read-only mode, only the ioctls
> + * that don't interfere at the tune logic should be accepted.
Nit:
with the tune logic
> + * That allows an external application to monitor the DVB QoS and
> + * statistics parameters.
> + *
> + * That matches all _IOR() ioctls, except for two special cases:
> + * - FE_GET_EVENT is part of the tuning logic on a DVB application;
> + * - FE_DISEQC_RECV_SLAVE_REPLY is part of DiSEqC 2.0
> + * setup
> + * So, those two ioctls should also return -EPERM, as otherwise
> + * reading from them would interfere with a DVB tune application
> + */
> + if ((file->f_flags & O_ACCMODE) == O_RDONLY
> + && (_IOC_DIR(cmd) != _IOC_READ
> + || cmd == FE_GET_EVENT
> + || cmd == FE_DISEQC_RECV_SLAVE_REPLY)) {
> up(&fepriv->sem);
> return -EPERM;
> }
>
Looks good to me
Reviewed by: Shuah Khan
thanks,
-- Shuah
