[PATCH v3 0/4] Add a new ima_hook buffer_check to measure buffers critical for attestation

Prakhar Srivastava
2019-04-29T21:47:52Z

For Kexec scenario(kexec_file_load) cmdline args are passed to the
next kerenel. These cmldine args used to load the next kernel can
have undesired/unwanted configs. To guard against any unwanted cmdline
args being passed to the next kernel. The current kernel should measure
the cmdline args to the next kernel, the same takes place in the EFI
bootloader. Thus on kexec the boot_aggregate does not change.

Currently the cmdline args are not measured, this changeset adds a new
ima and LSM hook for buffer measure and calls into the same to measure
the cmdline args passed to the next kernel.The cdmline args meassured
can then be used as an attestation criteria.

The ima logs need to injected into the next kernel, which will be followed
up by other patchsets.

Changelog:
v3: (rebase changes to next-general)
- Add policy checks for buffer[suggested by Mimi Zohar]
- use the IMA_XATTR to add buffer
- Add kexec_cmdline used for kexec file load
- Add an LSM hook to allow usage by other LSM.[suggestd by Mimi Zohar]

v2:
- Add policy checks for buffer[suggested by Mimi Zohar]
- Add an LSM hook to allow usage by other LSM.[suggestd by Mimi Zohar]
- use the IMA_XATTR to add buffer instead of sig template

v1:
-Add kconfigs to control the ima_buffer_check
-measure the cmdline args suffixed with the kernel file name
-add the buffer to the template sig field.
Prakhar Srivastava (4):
added a new ima policy func buffer_check, and ima hook to measure the
buffer hash into ima
add the buffer to the xattr
add kexec_cmdline used to ima
added LSM hook to call ima_buffer_check

Documentation/ABI/testing/ima_policy | 1 +
include/linux/ima.h | 5 +
include/linux/lsm_hooks.h | 3 +
include/linux/security.h | 3 +
kernel/kexec_core.c | 57 +++++++++++
kernel/kexec_file.c | 14 +++
kernel/kexec_internal.h | 4 +-
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_api.c | 1 +
security/integrity/ima/ima_main.c | 116 ++++++++++++++++++++++
security/integrity/ima/ima_policy.c | 8 ++
security/integrity/ima/ima_template_lib.c | 3 +-
security/integrity/integrity.h | 1 +
security/security.c | 6 ++
14 files changed, 221 insertions(+), 2 deletions(-)

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2.19.1