On Fri, Jan 12, 2018 at 10:11:18AM +0100, Stephan Mueller wrote:
> Am Freitag, 12. Januar 2018, 10:07:30 CET schrieb LABBE Corentin:
>
> > > > + __u64 stat_hash_tlen;
> > > >
> > > > };
> > >
> > > What I am slightly unsure here is: how should user space detect whether
> > > these additional parameters are part of the NETLINK_USER API or not? I
> > > use that interface in my libkcapi whose binary may be used on multiple
> > > different kernel versions. How should that library operate if one kernel
> > > has these parameters and another does not?
> >
> > Userspace could check for kernel version and know if stat are present or
> > not. Another way is to add a new netlink request.
>
> Well, I am not sure that checking the kernel version is good enough. Distros
> and other vendors may backport this patch. This means that for some older
> kernel versions this interface is present.
>
> Hence I would rather opt for a separate stat message where the user spacee
> caller receives an error on kernels that does not support it.
>
Herbert,
I have two way of adding a new netlink request
- keep the current patch and simply add a new CRYPTO_MSG_GETSTAT which use the
same function than CRYPTO_MSG_GETALG
=> minimal changes, in fact CRYPTO_MSG_GETSTAT and CRYPTO_MSG_GETALG
would be the same, but it is easy for userspace to test presence of stat.
- Create a new CRYPTO_MSG_GETSTAT which imply lot of code and add a new
crypto_user_stat.c
=> this imply also to change makefile (rename crypto_user.c to
crypto_user_base.c) since crypto_user.ko is made of two files.
Which one do you prefer ?
Regards
