On 16-08-04 08:24:29, Mimi Zohar wrote:
> The TPM PCRs are only reset on a hard reboot. In order to validate a
> TPM's quote after a soft reboot (eg. kexec -e), the IMA measurement list
> of the running kernel must be saved and restored on boot. This patch
> restores the measurement list.
>
> Changelog:
> - call ima_load_kexec_buffer() (Thiago)
>
> Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
> ---
> security/integrity/ima/Makefile | 1 +
> security/integrity/ima/ima.h | 10 ++
> security/integrity/ima/ima_init.c | 2 +
> security/integrity/ima/ima_kexec.c | 55 +++++++++++
> security/integrity/ima/ima_queue.c | 10 ++
> security/integrity/ima/ima_template.c | 171 ++++++++++++++++++++++++++++++++++
> 6 files changed, 249 insertions(+)
> create mode 100644 security/integrity/ima/ima_kexec.c
>
> diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
> index c34599f..c0ce7b1 100644
> --- a/security/integrity/ima/Makefile
> +++ b/security/integrity/ima/Makefile
> @@ -8,4 +8,5 @@ obj-$(CONFIG_IMA) += ima.o
> ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
> ima_policy.o ima_template.o ima_template_lib.o ima_buffer.o
> ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o
> +ima-$(CONFIG_KEXEC_FILE) += ima_kexec.o
> obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index b5728da..84e8d36 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -102,6 +102,13 @@ struct ima_queue_entry {
> };
> extern struct list_head ima_measurements; /* list of all measurements */
>
> +/* Some details preceding the binary serialized measurement list */
> +struct ima_kexec_hdr {
> + unsigned short version;
> + unsigned long buffer_size;
> + unsigned long count;
> +} __packed;
Unless there is no real need for this structure to be packed i suggest dropping
the attribute. When referenced through pointer 32bit ARM and MIPS (and likely
all other 32bit RISC CPUs) use rather inefficient byte loads and stores.
Worse, if, for example, ->count is going to be read/written concurrently from
multiple threads we get torn loads/stores thus losing atomicity of the access.
Petko
