Re: [PATCH v2 3/5] IB/hfi1: Add ioctl() interface for user commands

[Dennis Dalessandro]

On Thu, May 12, 2016 at 11:43:32AM -0600, Jason Gunthorpe wrote:
> On Thu, May 12, 2016 at 10:18:47AM -0700, Dennis Dalessandro wrote:
> > +	case HFI1_IOCTL_EP_INFO:
> > +	case HFI1_IOCTL_EP_ERASE_CHIP:
> > +	case HFI1_IOCTL_EP_ERASE_RANGE:
> > +	case HFI1_IOCTL_EP_READ_RANGE:
> > +	case HFI1_IOCTL_EP_WRITE_RANGE:
> > +		if (!capable(CAP_SYS_ADMIN))
> > +			return -EPERM;
> > +		if (copy_from_user(&ucmd,
> > +				   (struct hfi11_cmd __user *)arg,
> > +				   sizeof(ucmd)))
> > +			return -EFAULT;
> > +		return handle_eprom_command(fp, &ucmd);
>
> I thought we agreed to get rid of this as well? It certainly does not
> belong here, and as a general rule, I don't think ioctls should be
> doing capable tests..

Yeah. I left it in this patch set because this just "ports" our existing 
code to ioctl(). The eprom stuff is completely removed in another patch set 
that I posted shortly after this. It's at:

http://marc.info/?l=linux-rdma&m=146307409301822&w=2

> > +static inline int check_ioctl_access(unsigned int cmd, unsigned long arg)
> > +{
> > +	int read_cmd, write_cmd, read_ok, write_ok;
> > +
> > +	read_cmd = _IOC_DIR(cmd) & _IOC_READ;
> > +	write_cmd = _IOC_DIR(cmd) & _IOC_WRITE;
> > +	write_ok = access_ok(VERIFY_WRITE, (void __user *)arg, _IOC_SIZE(cmd));
> > +	read_ok = access_ok(VERIFY_READ, (void __user *)arg, _IOC_SIZE(cmd));
> > +
> > +	if ((read_cmd && !write_ok) || (write_cmd && !read_ok))
> > +		return -EFAULT;
>
> This seems kind of goofy, didn't Ira say this is performance senstive?

I'll let Ira comment here on the performance aspect. I agree it looks goofy.  
Suggestion on how to make it look better? Or are you saying this is 
incorrect?

> Driver shouldn't be open coding __get_user like that, IMHO.

Can you explain what you mean here? We should not use __get_user()?

> > +#define HFI1_IOCTL_RECV_CTRL \
> > +	_IOW(IB_IOCTL_MAGIC, HFI1_CMD_RECV_CTRL, int)
>
> Have you audited this? Confused why this is marked IOW when I see
> this:
>
> +       case HFI1_IOCTL_RECV_CTRL:
> +               ret = __get_user(uval, (int __user *)arg);
>
> Seeing many other examples.
>
> I stopped looking again

_IOW means user is writing data to the device. So the device is reading data 
from the user. Or am I missing your point?

-Denny