From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ua1-x949.google.com ([2607:f8b0:4864:20::949]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1h8qo0-0001Z1-1r for kexec@lists.infradead.org; Tue, 26 Mar 2019 18:28:13 +0000 Received: by mail-ua1-x949.google.com with SMTP id a10so1684670uan.7 for ; Tue, 26 Mar 2019 11:28:08 -0700 (PDT) Date: Tue, 26 Mar 2019 11:27:20 -0700 In-Reply-To: <20190326182742.16950-1-matthewgarrett@google.com> Message-Id: <20190326182742.16950-5-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190326182742.16950-1-matthewgarrett@google.com> Subject: [PATCH V31 04/25] kexec_load: Disable at runtime if the kernel is locked down From: Matthew Garrett List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: jmorris@namei.org Cc: Matthew Garrett , linux-api@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Matthew Garrett , dhowells@redhat.com, linux-security-module@vger.kernel.org, luto@kernel.org, Dave Young From: Matthew Garrett The kexec_load() syscall permits the loading and execution of arbitrary code in ring 0, which is something that lock-down is meant to prevent. It makes sense to disable kexec_load() in this situation. This does not affect kexec_file_load() syscall which can check for a signature on the image to be booted. Signed-off-by: David Howells Signed-off-by: Matthew Garrett Acked-by: Dave Young cc: kexec@lists.infradead.org --- kernel/kexec.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/kexec.c b/kernel/kexec.c index 68559808fdfa..57047acc9a36 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -207,6 +207,14 @@ static inline int kexec_load_check(unsigned long nr_segments, if (result < 0) return result; + /* + * kexec can be used to circumvent module loading restrictions, so + * prevent loading in that case + */ + if (kernel_is_locked_down("kexec of unsigned images", + LOCKDOWN_INTEGRITY)) + return -EPERM; + /* * Verify we have a legal set of flags * This leaves us room for future extensions. -- 2.21.0.392.gf8f6787159e-goog _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec