From: David Howells <dhowells@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: matthew.garrett@nebula.com, linux-efi@vger.kernel.org,
gnomes@lxorguk.ukuu.org.uk, gregkh@linuxfoundation.org,
dhowells@redhat.com, linux-security-module@vger.kernel.org,
keyrings@vger.kernel.org
Subject: [PATCH 07/24] kexec: Disable at runtime if the kernel is locked down
Date: Wed, 05 Apr 2017 18:08:00 +0100 [thread overview]
Message-ID: <149141208064.30815.2368765272350918233.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <149141201983.30815.1240162780237131881.stgit@warthog.procyon.org.uk>
From: Matthew Garrett <matthew.garrett@nebula.com>
kexec permits the loading and execution of arbitrary code in ring 0, which
is something that lock-down is meant to prevent. It makes sense to disable
kexec in this situation.
This does not affect kexec_file_load() which can check for a signature on the
image to be booted.
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---
kernel/kexec.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 980936a90ee6..46de8e6b42f4 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -194,6 +194,13 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
return -EPERM;
/*
+ * kexec can be used to circumvent module loading restrictions, so
+ * prevent loading in that case
+ */
+ if (kernel_is_locked_down())
+ return -EPERM;
+
+ /*
* Verify we have a legal set of flags
* This leaves us room for future extensions.
*/
next prev parent reply other threads:[~2017-04-05 17:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-05 17:07 [PATCH 00/24] Kernel lockdown David Howells
2017-04-05 17:07 ` [PATCH 01/24] efi: Add EFI_SECURE_BOOT bit David Howells
2017-04-05 17:07 ` [PATCH 02/24] Add the ability to lock down access to the running kernel image David Howells
2017-04-05 17:07 ` [PATCH 03/24] efi: Lock down the kernel if booted in secure boot mode David Howells
2017-04-05 17:07 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells
2017-04-05 17:07 ` [PATCH 05/24] Restrict /dev/mem and /dev/kmem when " David Howells
2017-04-05 17:07 ` [PATCH 06/24] Add a sysrq option to exit secure boot mode David Howells
2017-04-05 17:08 ` David Howells [this message]
2017-04-05 17:08 ` [PATCH 08/24] Copy secure_boot flag in boot params across kexec reboot David Howells
2017-04-07 16:32 ` [PATCH 00/24] Kernel lockdown Justin Forbes
2017-04-05 17:09 David Howells
2017-04-05 17:10 ` [PATCH 07/24] kexec: Disable at runtime if the kernel is locked down David Howells
2017-04-05 20:14 [PATCH 00/24] Kernel lockdown David Howells
2017-04-05 20:15 ` [PATCH 07/24] kexec: Disable at runtime if the kernel is locked down David Howells
2017-04-07 3:07 ` Dave Young
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