6 messages, 3 authors, 2018-03-25 · open the first message on its own page
From: David Miller <davem@davemloft.net>
Date: 2018-03-16 19:30:20
Although the top level ioctls are probably size and layout compatible, I do not think that the deeper ioctls can be called by compat binaries without some translations in order for them to work.
From: Sonny Rao <hidden>
Date: 2018-03-17 00:54:34
On Fri, Mar 16, 2018 at 12:30 PM, David Miller [off-list ref] wrote:
Although the top level ioctls are probably size and layout compatible, I do not think that the deeper ioctls can be called by compat binaries without some translations in order for them to work.
Ok, thanks -- I have only tested VHOST_VSOCK_SET_GUEST_CID and VHOST_VSOCK_SET_RUNNING but by deeper ioctls I think you might mean the ioctls under vhost_dev_ioctl() and vhost_vring_ioctl()?
From: David Miller <davem@davemloft.net>
Date: 2018-03-17 13:24:10
From: Sonny Rao <redacted> Date: Fri, 16 Mar 2018 17:54:12 -0700
On Fri, Mar 16, 2018 at 12:30 PM, David Miller [off-list ref] wrote:quoted
Although the top level ioctls are probably size and layout compatible, I do not think that the deeper ioctls can be called by compat binaries without some translations in order for them to work.Ok, thanks -- I have only tested VHOST_VSOCK_SET_GUEST_CID and VHOST_VSOCK_SET_RUNNING but by deeper ioctls I think you might mean the ioctls under vhost_dev_ioctl() and vhost_vring_ioctl()?
Yes.
From: Stefan Hajnoczi <hidden>
Date: 2018-03-22 09:25:36
On Fri, Mar 16, 2018 at 7:30 PM, David Miller [off-list ref] wrote:
Although the top level ioctls are probably size and layout compatible, I do not think that the deeper ioctls can be called by compat binaries without some translations in order for them to work.
I audited the vhost ioctl code when reviewing this patch and was unable to find anything that would break for a 32-bit userspace process. drivers/vhost/net.c does the same thing already, which doesn't prove it's correct but makes me more confident I didn't miss something while auditing the vhost ioctl code. Did you have a specific ioctl in mind? Stefan
From: Sonny Rao <hidden>
Date: 2018-03-22 20:38:59
On Thu, Mar 22, 2018 at 2:25 AM, Stefan Hajnoczi [off-list ref] wrote:
On Fri, Mar 16, 2018 at 7:30 PM, David Miller [off-list ref] wrote:quoted
Although the top level ioctls are probably size and layout compatible, I do not think that the deeper ioctls can be called by compat binaries without some translations in order for them to work.I audited the vhost ioctl code when reviewing this patch and was unable to find anything that would break for a 32-bit userspace process. drivers/vhost/net.c does the same thing already, which doesn't prove it's correct but makes me more confident I didn't miss something while auditing the vhost ioctl code. Did you have a specific ioctl in mind?
I think he means that we need to use the compat_ptr macro on any other pointers we get from userspace in those other ioctls. For most architectures this macro doesn't seem to do much but it does on some -- I think s390 modifies the pointer.
Stefan
From: David Miller <davem@davemloft.net>
Date: 2018-03-25 20:50:55
From: Stefan Hajnoczi <redacted> Date: Thu, 22 Mar 2018 09:25:35 +0000
On Fri, Mar 16, 2018 at 7:30 PM, David Miller [off-list ref] wrote:quoted
Although the top level ioctls are probably size and layout compatible, I do not think that the deeper ioctls can be called by compat binaries without some translations in order for them to work.I audited the vhost ioctl code when reviewing this patch and was unable to find anything that would break for a 32-bit userspace process. drivers/vhost/net.c does the same thing already, which doesn't prove it's correct but makes me more confident I didn't miss something while auditing the vhost ioctl code. Did you have a specific ioctl in mind?
I walked over the vhost ioctl datastructures and they all appear like they should be compatible. So I guess it won't be a problem after all.