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

From: Matthew Garrett
Date: Wed Mar 06 2019 - 19:01:43 EST


From: Jiri Bohac <jbohac@xxxxxxx>

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@xxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-by: Jiri Bohac <jbohac@xxxxxxx>
Cc: Matthew Garrett <mjg59@xxxxxxxxxxxxx>
cc: Chun-Yi Lee <jlee@xxxxxxxx>
cc: kexec@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Matthew Garrett <matthewgarrett@xxxxxxxxxx>
---
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