[PATCH v1 0/5] LSM: Measure security module state
nramas at linux.microsoft.com
Wed Jul 15 15:48:48 UTC 2020
Critical data structures of security modules are currently not measured.
Therefore an attestation service, for instance, would not be able to
attest whether the security modules are always operating with the policies
and configuration that the system administrator had setup. The policies
and configuration for the security modules could be tampered with by
malware by exploiting Kernel vulnerabilities or modified through some
inadvertent actions on the system. Measuring such critical data would
enable an attestation service to better assess the state of the system.
IMA subsystem measures system files, command line arguments passed to
kexec, boot aggregate, keys, etc. It can be used to measure critical
data structures of security modules as well.
This change aims to address measuring critical data structures
of security modules when they are initialized, when they are updated
at runtime, and also periodically to detect any tampering.
This change set is based off of Linux Kernel version 5.8-rc5.
The following patch needs to be applied first before applying
the patches in this patch set:
=> Per Stephen Smalley's suggestion added selinux_state booleans
and hash of SELinux policy in the measured data for SELinux.
=> Call IMA hook from the security module directly instead of
redirecting through the LSM.
Lakshmi Ramasubramanian (5):
IMA: Add LSM_STATE func to measure LSM data
IMA: Define an IMA hook to measure LSM data
LSM: Add security_state function pointer in lsm_info struct
LSM: Define SELinux function to measure security state
LSM: Define workqueue for measuring security module state
Documentation/ABI/testing/ima_policy | 6 +-
include/linux/ima.h | 4 +
include/linux/lsm_hooks.h | 3 +
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_api.c | 2 +-
security/integrity/ima/ima_main.c | 17 ++++
security/integrity/ima/ima_policy.c | 29 +++++--
security/security.c | 74 +++++++++++++++-
security/selinux/Makefile | 2 +
security/selinux/hooks.c | 2 +
security/selinux/include/security.h | 19 +++++
security/selinux/measure.c | 122 +++++++++++++++++++++++++++
security/selinux/selinuxfs.c | 1 +
security/selinux/ss/services.c | 23 ++++-
14 files changed, 293 insertions(+), 12 deletions(-)
create mode 100644 security/selinux/measure.c
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