| Message ID | 31b56d74c88c3d6a867468299e0498ebc15fcf63.1505933919.git.mchehab@s-opensource.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/20/2017 01:11 PM, 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 <mchehab@s-opensource.com> > --- > 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 01bd19fd4c57..7dda5acea3f2 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; > } > Same comment from your previous series. I started looking at the old series and now the latest. Didn't realize the series has been revised. :( Looks good to me Reviewed by: Shuah Khan <shuahkh@osg.samsung.com> thanks, -- Shuah
diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index 01bd19fd4c57..7dda5acea3f2 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. + * 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; }
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 <mchehab@s-opensource.com> --- drivers/media/dvb-core/dvb_frontend.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)