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SubjectRe: [PATCH] seccomp: rework define for SECCOMP_USER_NOTIF_FLAG_CONTINUE
On Thu, Oct 24, 2019 at 11:25:39PM +0200, Christian Brauner wrote:
> Switch from BIT(0) to (1UL << 0).
> First, there are already two different forms used in the header, so there's
> no need to add a third. Second, the BIT() macros is kernel internal and
> afaict not actually exposed to userspace. Maybe there's some magic there
> I'm missing but it definitely causes issues when compiling a program that
> tries to use SECCOMP_USER_NOTIF_FLAG_CONTINUE. It currently fails in the
> following way:
>
> # github.com/lxc/lxd/lxd
> /usr/bin/ld: $WORK/b001/_x003.o: in function
> `__do_user_notification_continue':
> lxd/main_checkfeature.go:240: undefined reference to `BIT'
> collect2: error: ld returned 1 exit status
>
> Switching to (1UL << 0) should prevent that and is more in line what is
> already done in the rest of the header.

Hmpf. I thought those were already exported into the UAPI. Ah well.
Thanks! Applied.

-Kees

>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Andy Lutomirski <luto@amacapital.net>
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
> ---
> include/uapi/linux/seccomp.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/seccomp.h b/include/uapi/linux/seccomp.h
> index 61fbbb7c1ee9..9099972200cd 100644
> --- a/include/uapi/linux/seccomp.h
> +++ b/include/uapi/linux/seccomp.h
> @@ -102,7 +102,7 @@ struct seccomp_notif {
> * SECCOMP_USER_NOTIF_FLAG_CONTINUE. Note that SECCOMP_RET_USER_NOTIF can
> * equally be overriden by SECCOMP_USER_NOTIF_FLAG_CONTINUE.
> */
> -#define SECCOMP_USER_NOTIF_FLAG_CONTINUE BIT(0)
> +#define SECCOMP_USER_NOTIF_FLAG_CONTINUE (1UL << 0)
>
> struct seccomp_notif_resp {
> __u64 id;
> --
> 2.23.0
>

--
Kees Cook

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