From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: [PATCH 08/12] kexec: Disable at runtime if securelevel has been set. Date: Mon, 9 Sep 2013 11:49:42 -0400 Message-ID: <1378741786-18430-9-git-send-email-matthew.garrett@nebula.com> References: <1378741786-18430-1-git-send-email-matthew.garrett@nebula.com> Return-path: In-Reply-To: <1378741786-18430-1-git-send-email-matthew.garrett@nebula.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: keescook@chromium.org, gregkh@linuxfoundation.org, hpa@zytor.com, linux-efi@vger.kernel.org, jmorris@namei.org, linux-security-module@vger.kernel.org, Matthew Garrett List-Id: linux-efi@vger.kernel.org kexec permits the loading and execution of arbitrary code in ring 0, which permits the modification of the running kernel. Prevent this if securelevel has been set. Signed-off-by: Matthew Garrett --- kernel/kexec.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/kexec.c b/kernel/kexec.c index 59f7b55..98db2a1 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include @@ -942,6 +943,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, if (!capable(CAP_SYS_BOOT)) return -EPERM; + if (get_securelevel() > 0) + return -EPERM; + /* * Verify we have a legal set of flags * This leaves us room for future extensions. -- 1.8.3.1