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
