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[45/47,X] UBUNTU: SAUCE: (efi-lockdown) kexec_file: Disable at runtime if the kernel is locked down

Message ID 20200618231258.630575-46-seth.forshee@canonical.com
State New
Headers show
Series Lockdown updates | expand

Commit Message

Seth Forshee June 18, 2020, 11:12 p.m. UTC 
From: Chun-Yi Lee <joeyli.kernel@gmail.com>

BugLink: https://bugs.launchpad.net/bugs/1884159

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

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>
Reviewed-by: James Morris <james.l.morris@oracle.com>
cc: kexec@lists.infradead.org
(backported from commit 6620737c201ed7242dbb672803085b46ae600ce7
 git://git.kernel.org/pub/scm/linux/kernel/git/jwboyer/fedora.git)
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
---
 kernel/kexec_file.c | 6 ++++++
 1 file changed, 6 insertions(+)
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Patch

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 6030efd4a188..14d19eda9ec9 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -317,6 +317,12 @@  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) && secure_modules())
+		return -EPERM;
+
 	/* Make sure we have a legal set of flags */
 	if (flags != (flags & KEXEC_FILE_FLAGS))
 		return -EINVAL;