[PATCH V2 01/10] Secure boot: Add new capability

From: Matthew Garrett
Date: Thu Sep 20 2012 - 10:47:25 EST


Secure boot adds certain policy requirements, including that root must not
be able to do anything that could cause the kernel to execute arbitrary code.
The simplest way to handle this would seem to be to add a new capability
and gate various functionality on that. We'll then strip it from the initial
capability set if required.

Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
---
include/linux/capability.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/capability.h b/include/linux/capability.h
index d10b7ed..4345bc8 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -364,7 +364,11 @@ struct cpu_vfs_cap_data {

#define CAP_BLOCK_SUSPEND 36

-#define CAP_LAST_CAP CAP_BLOCK_SUSPEND
+/* Allow things that trivially permit root to modify the running kernel */
+
+#define CAP_COMPROMISE_KERNEL 37
+
+#define CAP_LAST_CAP CAP_COMPROMISE_KERNEL

#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)

--
1.7.11.4

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