[PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set

From	David Howells <dhowells@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set
Date	2017-04-05 19:20 +0200
Message-ID	<tsWL9-5w8-27@gated-at.bofh.it> (permalink)
References	<tsWL8-5w8-5@gated-at.bofh.it>
Organization	Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

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From: Chun-Yi Lee <joeyli.kernel@gmail.com>

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>
---

 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;
+
 	/* Make sure we have a legal set of flags */
 	if (flags != (flags & KEXEC_FILE_FLAGS))
 		return -EINVAL;

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[PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set David Howells <dhowells@redhat.com> - 2017-04-05 19:20 +0200

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