Re: [PATCH 05/11] UAPI: coda: Don't use internal kernel structs in UAPI
From: Yann Droneaud <hidden>
Date: 2018-09-05 17:12:37
Also in:
linux-fsdevel, linux-kbuild, lkml
Le mercredi 05 septembre 2018 à 16:55 +0100, David Howells a écrit :
quoted hunk ↗ jump to hunk
The size and layout of internal kernel structures may not be relied upon outside of the kernel and may even change in a containerised environment if a container image is frozen and shifted to another machine. Excise these from Coda's upc_req struct. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jan Harkes <jaharkes@cs.cmu.edu> cc: coda@cs.cmu.edu cc: codalist@coda.cs.cmu.edu cc: linux-fsdevel@vger.kernel.org --- include/uapi/linux/coda_psdev.h | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/include/uapi/linux/coda_psdev.h b/include/uapi/linux/coda_psdev.h index aa6623efd2dd..9c3acde393cd 100644 --- a/include/uapi/linux/coda_psdev.h +++ b/include/uapi/linux/coda_psdev.h@@ -10,14 +10,18 @@ /* messages between coda filesystem in kernel and Venus */ struct upc_req { +#ifdef __KERNEL__ struct list_head uc_chain; +#endif caddr_t uc_data; u_short uc_flags; u_short uc_inSize; /* Size is at most 5000 bytes */ u_short uc_outSize; u_short uc_opcode; /* copied from data to save lookup */ int uc_unique; +#ifdef __KERNEL__ wait_queue_head_t uc_sleep; /* process' wait queue */ +#endif };
This structure should not have been exposed to userspace in the first
place: it's unusable by userspace as it is. It was incorrect to have it
outside of #ifdef __KERNEL__ before commit 607ca46e97a1b ...
... and it's not exchanged between kernel and userspace, see
coda_psdev_write():
struct upc_req *req = NULL;
...
if (copy_from_user(req->uc_data, buf, nbytes)) {
req->uc_flags |= CODA_REQ_ABORT;
wake_up(&req->uc_sleep);
retval = -EFAULT;
goto out;
}
Only data, a caddr_t, is read from userspace.
So the structure can be moved back to <linux/coda_psdev.h>.
#define CODA_REQ_ASYNC 0x1
All CODA_REQ_* defines internals to kernel side and not exchanged with userspace. Please move them back to <linux/coda_psdev.h> Regards. -- Yann Droneaud OPTEYA