Hi Mimi,

I've adjusted the patch as below.

David
---
commit bf33218ad2bf04f1b92f5c32499ab906f107864c
Author: Chun-Yi Lee <joeyli.ker...@gmail.com>
Date:   Wed May 24 14:56:03 2017 +0100

    kexec_file: Restrict at runtime if the kernel is locked down
    
    When KEXEC_VERIFY_SIG is not enabled, kernel should not load images through
    kexec_file systemcall if the kernel is locked down unless IMA can be used
    to validate the image.
    
    This code was showed in Matthew's patch but not in git:
    https://lkml.org/lkml/2015/3/13/778
    
    Cc: Matthew Garrett <mj...@srcf.ucam.org>
    Signed-off-by: Chun-Yi Lee <j...@suse.com>
    Signed-off-by: David Howells <dhowe...@redhat.com>
    Reviewed-by: James Morris <james.l.mor...@oracle.com>
    cc: ke...@lists.infradead.org

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 9f48f4412297..3ba28fc3fab0 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -255,6 +255,14 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, 
initrd_fd,
        if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
                return -EPERM;
 
+       /* Don't permit images to be loaded into trusted kernels if we're not
+        * going to verify the signature on them
+        */
+       if (!IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) &&
+           !is_ima_appraise_enabled() &&
+           kernel_is_locked_down("kexec of unsigned images"))
+               return -EPERM;
+
        /* Make sure we have a legal set of flags */
        if (flags != (flags & KEXEC_FILE_FLAGS))
                return -EINVAL;
--
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