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Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list

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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@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

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[PATCH 1/7] ima: on soft reboot, restore the measurement list Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-08-04 15:50 +0200
  Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Petko Manolov <petkan@mip-labs.com> - 2016-08-05 11:30 +0200
    Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-08-05 15:40 +0200
      Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Petko Manolov <petkan@mip-labs.com> - 2016-08-05 18:00 +0200
  Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Michael Ellerman <mpe@ellerman.id.au> - 2016-08-09 13:10 +0200
    Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-08-09 15:10 +0200
      Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-08-09 15:20 +0200
        RE: [PATCH 1/7] ima: on soft reboot, restore the measurement list David Laight <David.Laight@ACULAB.COM> - 2016-08-09 15:40 +0200
          Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-08-09 16:10 +0200
        Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-08-09 16:00 +0200
          Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-08-09 16:10 +0200
        Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Samuel Mendoza-Jonas <sam@mendozajonas.com> - 2016-08-10 01:30 +0200
        Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Michael Ellerman <mpe@ellerman.id.au> - 2016-08-10 05:50 +0200
          Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Michael Ellerman <mpe@ellerman.id.au> - 2016-08-10 20:10 +0200
            Re: [Linux-ima-devel] [PATCH 1/7] ima: on soft reboot, restore the  measurement list Petko Manolov <petkan@mip-labs.com> - 2016-08-10 20:30 +0200
              Re: [Linux-ima-devel] [PATCH 1/7] ima: on soft reboot, restore the  measurement list Petko Manolov <petkan@mip-labs.com> - 2016-08-10 22:20 +0200
              RE: [Linux-ima-devel] [PATCH 1/7] ima: on soft reboot, restore the  measurement list David Laight <David.Laight@ACULAB.COM> - 2016-08-10 23:20 +0200
            Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-08-10 20:50 +0200
          Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-08-10 20:10 +0200

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