linux-kernel - [PATCH 08/27] kexec_file: Restrict at runtime if the kernel is locked down

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Date:   Wed,  6 Mar 2019 15:58:54 -0800
From:   Matthew Garrett <matthewgarrett@...gle.com>
To:     jmorris@...ei.org
Cc:     linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, dhowells@...hat.com
Subject: [PATCH 08/27] kexec_file: Restrict at runtime if the kernel is locked down

From: Jiri Bohac <jbohac@...e.cz>

When KEXEC_SIG is not enabled, kernel should not load images through
kexec_file systemcall if the kernel is locked down.

[Modified by David Howells to fit with modifications to the previous patch
 and to return -EPERM if the kernel is locked down for consistency with
 other lockdowns. Modified by Matthew Garrett to remove the IMA
 integration, which will be replaced by integrating with the IMA
 architecture policy patches.]

Signed-off-by: Jiri Bohac <jbohac@...e.cz>
Signed-off-by: David Howells <dhowells@...hat.com>
Reviewed-by: Jiri Bohac <jbohac@...e.cz>
Cc: Matthew Garrett <mjg59@...f.ucam.org>
cc: Chun-Yi Lee <jlee@...e.com>
cc: kexec@...ts.infradead.org
Signed-off-by: Matthew Garrett <matthewgarrett@...gle.com>
---
 kernel/kexec_file.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 67f3a866eabe..0cfe4f6f7f85 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -239,6 +239,12 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 		}
 
 		ret = 0;
+
+		if (kernel_is_locked_down(reason)) {
+			ret = -EPERM;
+			goto out;
+		}
+
 		break;
 
 		/* All other errors are fatal, including nomem, unparseable
-- 
2.21.0.352.gf09ad66450-goog