path: root/security/integrity
diff options
authorRaphael Gianotti <>2021-01-26 11:14:53 -0800
committerMimi Zohar <>2021-01-26 19:06:41 -0500
commitb3f82afc1041a6a7d5347a01883f4aab7ec133b2 (patch)
tree37661465598d37a315af6fa78e58bf0181a02e7b /security/integrity
parente58bb688f2e44237990dfb68ea8cb2449efde7da (diff)
IMA: Measure kernel version in early boot
The integrity of a kernel can be verified by the boot loader on cold boot, and during kexec, by the current running kernel, before it is loaded. However, it is still possible that the new kernel being loaded is older than the current kernel, and/or has known vulnerabilities. Therefore, it is imperative that an attestation service be able to verify the version of the kernel being loaded on the client, from cold boot and subsequent kexec system calls, ensuring that only kernels with versions known to be good are loaded. Measure the kernel version using ima_measure_critical_data() early on in the boot sequence, reducing the chances of known kernel vulnerabilities being exploited. With IMA being part of the kernel, this overall approach makes the measurement itself more trustworthy. To enable measuring the kernel version "ima_policy=critical_data" needs to be added to the kernel command line arguments. For example, BOOT_IMAGE=/boot/vmlinuz-5.11.0-rc3+ root=UUID=fd643309-a5d2-4ed3-b10d-3c579a5fab2f ro nomodeset ima_policy=critical_data If runtime measurement of the kernel version is ever needed, the following should be added to /etc/ima/ima-policy: measure func=CRITICAL_DATA label=kernel_info To extract the measured data after boot, the following command can be used: grep -m 1 "kernel_version" \ /sys/kernel/security/integrity/ima/ascii_runtime_measurements Sample output from the command above: 10 a8297d408e9d5155728b619761d0dd4cedf5ef5f ima-buf sha256:5660e19945be0119bc19cbbf8d9c33a09935ab5d30dad48aa11f879c67d70988 kernel_version 352e31312e302d7263332d31363138372d676564623634666537383234342d6469727479 The above hex-ascii string corresponds to the kernel version (e.g. xxd -r -p): 5.11.0-rc3-16187-gedb64fe78244-dirty Signed-off-by: Raphael Gianotti <> Signed-off-by: Mimi Zohar <>
Diffstat (limited to 'security/integrity')
1 files changed, 5 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index 4902fe7bd570..6e8742916d1d 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -15,6 +15,8 @@
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/err.h>
+#include <linux/ima.h>
+#include <generated/utsrelease.h>
#include "ima.h"
@@ -147,5 +149,8 @@ int __init ima_init(void)
+ ima_measure_critical_data("kernel_info", "kernel_version",
+ UTS_RELEASE, strlen(UTS_RELEASE), false);
return rc;