On 6/15/21 7:46 PM, Mathieu Poirier wrote:
> On Fri, Jun 04, 2021 at 11:14:05AM +0200, Arnaud Pouliquen wrote:
>> Using the RPMSG_RELEASE_DEV_IOCTL is possible to remove any
>> rpmsg device (such as the rpmsg ns or the rpmsg ctrldev).
>>
>> Add a new field to store the removability of the device.
>>
>> By default the rpmsg device can not be removed by user space. It is
>> set to 1 by the rpmsg ctrl on RPMSG_CREATE_DEV_IOCTL request, but
>> could also be set by an rpmsg driver during probe.
>>
>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
>> ---
>> drivers/rpmsg/rpmsg_ctrl.c | 17 ++++++++++++++++-
>> include/linux/rpmsg.h | 2 ++
>> 2 files changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c
>> index cb19e32d05e1..e93c6ec49038 100644
>> --- a/drivers/rpmsg/rpmsg_ctrl.c
>> +++ b/drivers/rpmsg/rpmsg_ctrl.c
>> @@ -74,6 +74,7 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
>> struct rpmsg_endpoint_info eptinfo;
>> struct rpmsg_channel_info chinfo;
>> struct rpmsg_device *rpdev;
>> + struct device *dev;
>> int ret = 0;
>>
>> if (copy_from_user(&eptinfo, argp, sizeof(eptinfo)))
>> @@ -95,11 +96,25 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
>> if (!rpdev) {
>> dev_err(&ctrldev->dev, "failed to create %s channel\n", chinfo.name);
>> ret = -ENXIO;
>> + } else {
>> + /* Allow user space to release the device. */
>> + rpdev->us_removable = 1;
>
> As a rule of thumb I try really hard to avoid introducing new flags. In this case we
> can attain the same result by looking at chinfo->name, chinfo->src and
> chinfo->dst. I would introduce a new inline function in rpmsg_internal.h,
> something like rpmsg_chrdev_is_ctrl_dev(), and compare the specifics in chinfo
> to rpdev->id.name, rpdev->src and rpdev->dst. If they all match then the
> operation is refused.
Something must have escaped me, because i turn around your your proposal,
without understand it.
The "us_removable" flag is not only for the rpmsg_ctrl, but for any rpmsg device
that have not to be released by user application. Either because there are core
( rpmsg_ctrl, rpmsg_ns) or because a rpmsg driver don't allow to unbind its
rpmsg devices.
look to me that rpmsg_chrdev_is_ctrl_dev just prevents rpmsg ctrl to be released
by the RPMSG_RELEASE_DEV_IOCTL.
Please, could you clarify what you have in mind here?
Thanks,
Arnaud
>
> That way we don't introduce a new flag and there is also no need to call
> rpmsg_find_device() twice.
>
> Thanks,
> Mathieu
>
>> }
>> break;
>>
>> case RPMSG_RELEASE_DEV_IOCTL:
>> - ret = rpmsg_release_channel(ctrldev->rpdev, &chinfo);
>> + dev = rpmsg_find_device(ctrldev->rpdev->dev.parent, &chinfo);
>> + if (!dev)
>> + ret = -ENXIO;
>> +
>> + /* Verify that rpmsg device removal is allowed. */
>> + if (!ret) {
>> + rpdev = to_rpmsg_device(dev);
>> + if (!rpdev->us_removable)
>> + ret = -EACCES;
>> + }
>> + if (!ret)
>> + ret = rpmsg_release_channel(ctrldev->rpdev, &chinfo);
>> if (ret)
>> dev_err(&ctrldev->dev, "failed to release %s channel (%d)\n",
>> chinfo.name, ret);
>> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
>> index d97dcd049f18..3642aad1a789 100644
>> --- a/include/linux/rpmsg.h
>> +++ b/include/linux/rpmsg.h
>> @@ -47,6 +47,7 @@ struct rpmsg_channel_info {
>> * @ept: the rpmsg endpoint of this channel
>> * @announce: if set, rpmsg will announce the creation/removal of this channel
>> * @little_endian: True if transport is using little endian byte representation
>> + * @us_removable: True if userspace application has permission to remove the rpmsg device
>> */
>> struct rpmsg_device {
>> struct device dev;
>> @@ -57,6 +58,7 @@ struct rpmsg_device {
>> struct rpmsg_endpoint *ept;
>> bool announce;
>> bool little_endian;
>> + bool us_removable;
>>
>> const struct rpmsg_device_ops *ops;
>> };
>> --
>> 2.17.1
>>
