The motive behind the patch series is to measure the boot cmdline args used for soft reboot/kexec case. For secure boot attestation, it is necessary to measure the kernel command line and the kernel version. For cold boot, the boot loader can be enhanced to measure these parameters. (https://mjg59.dreamwidth.org/48897.html) However, for attestation across soft reboot boundary, these values also need to be measured during kexec_file_load. Currently for Kexec(kexec_file_load)/soft reboot scenario the boot cmdline args for the next kernel are not measured. For normal case of boot/hardreboot the cmdline args are measured into the TPM. The hash of boot command line is calculated and added to the current running kernel's measurement list. On a soft reboot like kexec, no cmdline arguments measurement takes place. To achive the above the patch series does the following -adds a new ima hook: ima_kexec_cmdline which measures the cmdline args into the ima log, behind a new ima policy entry KEXEC_CMDLINE. -since the cmldine args cannot be appraised, a new template field(buf) is added. The template field contains the buffer passed(cmldine args), which can be used to appraise/attest at a later stage. -call the ima_kexec_cmdline(...) hook from kexec_file_load call. The ima logs need to be carried over to the next kernel, which will be followed up by other patchsets for x86_64 and arm64. The kexec cmdline hash can be verified using sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | grep kexec-cmdline | cut -d' ' -f 6 | xxd -r -p | sha256sum Changelog: V7: - rebased to next-queued-testing https://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git/log/?h=next-queued-testing V6: -add a new ima hook and policy to measure the cmdline args(ima_kexec_cmdline) -add a new template field buf to contain the buffer measured. [suggested by Mimi Zohar] add new fields to ima_event_data to store/read buffer data. [suggested by Roberto] -call ima_kexec_cmdline from kexec_file_load path v5: -add a new ima hook and policy to measure the cmdline args(ima_kexec_cmdline) -add a new template field buf to contain the buffer measured. [suggested by Mimi Zohar] -call ima_kexec_cmdline from kexec_file_load path v4: - per feedback from LSM community, removed the LSM hook and renamed the IMA policy to KEXEC_CMDLINE 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 (3): Add a new ima hook ima_kexec_cmdline to measure cmdline args add a new ima template field buf call ima_kexec_cmdline to measure the cmdline args Documentation/ABI/testing/ima_policy | 1 + Documentation/security/IMA-templates.rst | 2 +- include/linux/ima.h | 2 + kernel/kexec_file.c | 8 ++- security/integrity/ima/ima.h | 3 + security/integrity/ima/ima_api.c | 5 +- security/integrity/ima/ima_init.c | 2 +- security/integrity/ima/ima_main.c | 80 +++++++++++++++++++++++ security/integrity/ima/ima_policy.c | 9 +++ security/integrity/ima/ima_template.c | 2 + security/integrity/ima/ima_template_lib.c | 20 ++++++ security/integrity/ima/ima_template_lib.h | 4 ++ 12 files changed, 131 insertions(+), 7 deletions(-) -- 2.17.1
