The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From fb14528e443646dd3fd02df4437fcf5265b66baa Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= mic@linux.microsoft.com Date: Fri, 30 Oct 2020 13:38:49 +0100 Subject: [PATCH] seccomp: Set PF_SUPERPRIV when checking capability MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

Replace the use of security_capable(current_cred(), ...) with ns_capable_noaudit() which set PF_SUPERPRIV.

Since commit 98f368e9e263 ("kernel: Add noaudit variant of ns_capable()"), a new ns_capable_noaudit() helper is available. Let's use it!

Cc: Jann Horn jannh@google.com Cc: Kees Cook keescook@chromium.org Cc: Tyler Hicks tyhicks@linux.microsoft.com Cc: Will Drewry wad@chromium.org Cc: stable@vger.kernel.org Fixes: e2cfabdfd075 ("seccomp: add system call filtering using BPF") Signed-off-by: Mickaël Salaün mic@linux.microsoft.com Reviewed-by: Jann Horn jannh@google.com Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20201030123849.770769-3-mic@digikod.net

diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 8ad7a293255a..53a7d1512dd7 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -38,7 +38,7 @@ #include <linux/filter.h> #include <linux/pid.h> #include <linux/ptrace.h> -#include <linux/security.h> +#include <linux/capability.h> #include <linux/tracehook.h> #include <linux/uaccess.h> #include <linux/anon_inodes.h> @@ -558,8 +558,7 @@ static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) * behavior of privileged children. */ if (!task_no_new_privs(current) && - security_capable(current_cred(), current_user_ns(), - CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) != 0) + !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN)) return ERR_PTR(-EACCES);

/* Allocate a new seccomp_filter */