On Mon, 2018-09-24 at 13:18 +0100, David Howells wrote:
> The keyctl_dh_params struct in uapi/linux/keyctl.h contains the
> symbol
> "private" which means that the header file will cause compilation
> failure
> if #included in to a C++ program. Further, the patch that added the
> same
> struct to the keyutils package named the symbol "priv", not
> "private".
>
> The previous attempt to fix this (commit 8a2336e549d3) did so by
> simply
> renaming the kernel's copy of the field to dh_private, but this then
> breaks
> existing userspace and as such has to be reverted (which is done by
> the
> preceding patch).
>
> [And note, to those who think that wrapping the struct in extern "C"
> {}
> will work: it won't; that only changes how symbol names are
> presented to
> the assembler and linker.].
>
> Instead, insert an anonymous union around the "private" member and
> add a
> second member in there with the name "priv" to match the one in the
> keyutils package. The "private" member is then wrapped in
> !__cplusplus
> cpp-conditionals to hide it from C++.
>
> Fixes: ddbb41148724 ("KEYS: Add KEYCTL_DH_COMPUTE command")
> Fixes: 8a2336e549d3 ("uapi/linux/keyctl.h: don't use C++ reserved
> keyword as a struct member name")
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> cc: Lubomir Rintel <lkundrak@xxxxx>
> cc: James Morris <jmorris@xxxxxxxxx>
> cc: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>
> cc: Stephan Mueller <smueller@xxxxxxxxxx>
> cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> cc: stable@xxxxxxxxxxxxxxx
> ---
>
> include/uapi/linux/keyctl.h | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/keyctl.h
> b/include/uapi/linux/keyctl.h
> index 7b8c9e19bad1..0f3cb13db8e9 100644
> --- a/include/uapi/linux/keyctl.h
> +++ b/include/uapi/linux/keyctl.h
> @@ -65,7 +65,12 @@
>
> /* keyctl structures */
> struct keyctl_dh_params {
> - __s32 private;
> + union {
> +#ifndef __cplusplus
> + __s32 private;
> +#endif
> + __s32 priv;
> + };
> __s32 prime;
> __s32 base;
> };
>
Thank you, checked that this works fine for libell build.
Tested-by: Lubomir Rintel <lkundrak@xxxxx>
Perhaps you may want to call the C++ friendly field "dh_private",
because there might be C++ users that utilize it already. (The chance
might be negligible though.).
Lubo
