On Fri, 2017-04-07 at 11:05 +0800, Dave Young wrote:

On 04/05/17 at 09:15pm, David Howells wrote:

quoted

From: Chun-Yi Lee <redacted>

When KEXEC_VERIFY_SIG is not enabled, kernel should not loads image
through kexec_file systemcall if securelevel has been set.

This code was showed in Matthew's patch but not in git:
https://lkml.org/lkml/2015/3/13/778

Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Chun-Yi Lee <jlee@suse.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: kexec at lists.infradead.org
---

 kernel/kexec_file.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b118735fea9d..f6937eecd1eb 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c

@@ -268,6 +268,12 @@ 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) && kernel_is_locked_down())
+		return -EPERM;
+
 

IMA can be used to verify file signatures too, based on the LSM hooks
in ?kernel_read_file_from_fd(). ?CONFIG_KEXEC_VERIFY_SIG should not be
required.

Mimi

	/* Make sure we have a legal set of flags */

quoted

 	if (flags != (flags & KEXEC_FILE_FLAGS))
 		return -EINVAL;


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Acked-by: Dave Young <redacted>

Thanks
Dave
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