Commit 4bd96a7a authored by Shane Wang's avatar Shane Wang Committed by H. Peter Anvin
Browse files

x86, tboot: Add support for S3 memory integrity protection 



This patch adds support for S3 memory integrity protection within an Intel(R)
TXT launched kernel, for all kernel and userspace memory.  All RAM used by the
kernel and userspace, as indicated by memory ranges of type E820_RAM and
E820_RESERVED_KERN in the e820 table, will be integrity protected.

The MAINTAINERS file is also updated to reflect the maintainers of the
TXT-related code.

All MACing is done in tboot, based on a complexity analysis and tradeoff.

v3: Compared with v2, this patch adds a check of array size in
tboot.c, and a note to specify which c/s of tboot supports this kind
of MACing in intel_txt.txt.

Signed-off-by: default avatarShane Wang <shane.wang@intel.com>
LKML-Reference: <4B973DDA.6050902@intel.com>
Signed-off-by: default avatarJoseph Cihula <joseph.cihula@intel.com>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Acked-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent a3d3203e

Documentation/intel_txt.txt

+9 −7
Original line number Diff line number Diff line
@@ -161,13 +161,15 @@ o In order to put a system into any of the sleep states after a TXT 
      has been restored, it will restore the TPM PCRs and then

      transfer control back to the kernel's S3 resume vector.

      In order to preserve system integrity across S3, the kernel

      provides tboot with a set of memory ranges (kernel

      code/data/bss, S3 resume code, and AP trampoline) that tboot

      will calculate a MAC (message authentication code) over and then

      seal with the TPM.  On resume and once the measured environment

      has been re-established, tboot will re-calculate the MAC and

      verify it against the sealed value.  Tboot's policy determines

      what happens if the verification fails.

      provides tboot with a set of memory ranges (RAM and RESERVED_KERN

      in the e820 table, but not any memory that BIOS might alter over

      the S3 transition) that tboot will calculate a MAC (message

      authentication code) over and then seal with the TPM. On resume

      and once the measured environment has been re-established, tboot

      will re-calculate the MAC and verify it against the sealed value.

      Tboot's policy determines what happens if the verification fails.

      Note that the c/s 194 of tboot which has the new MAC code supports

      this.



That's pretty much it for TXT support.

MAINTAINERS

+11 −0
Original line number Diff line number Diff line
@@ -2940,6 +2940,17 @@ S: Odd Fixes 
F:	Documentation/networking/README.ipw2200

F:	drivers/net/wireless/ipw2x00/ipw2200.*



INTEL(R) TRUSTED EXECUTION TECHNOLOGY (TXT)

M:	Joseph Cihula <joseph.cihula@intel.com>

M:	Shane Wang <shane.wang@intel.com>

L:	tboot-devel@lists.sourceforge.net

W:	http://tboot.sourceforge.net

T:	Mercurial http://www.bughost.org/repos.hg/tboot.hg

S:	Supported

F:	Documentation/intel_txt.txt

F:	include/linux/tboot.h

F:	arch/x86/kernel/tboot.c



INTEL WIRELESS WIMAX CONNECTION 2400

M:	Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>

M:	linux-wimax@intel.com

arch/x86/include/asm/e820.h

+6 −1
Original line number Diff line number Diff line
@@ -45,7 +45,12 @@ 
#define E820_NVS	4

#define E820_UNUSABLE	5



/* reserved RAM used by kernel itself */

/*

 * reserved RAM used by kernel itself

 * if CONFIG_INTEL_TXT is enabled, memory of this type will be

 * included in the S3 integrity calculation and so should not include

 * any memory that BIOS might alter over the S3 transition

 */

#define E820_RESERVED_KERN        128



#ifndef __ASSEMBLY__

arch/x86/kernel/tboot.c

+11 −9
Original line number Diff line number Diff line
@@ -175,6 +175,9 @@ static void add_mac_region(phys_addr_t start, unsigned long size) 
	struct tboot_mac_region *mr;

	phys_addr_t end = start + size;



	if (tboot->num_mac_regions >= MAX_TB_MAC_REGIONS)

		panic("tboot: Too many MAC regions\n");



	if (start && size) {

		mr = &tboot->mac_regions[tboot->num_mac_regions++];

		mr->start = round_down(start, PAGE_SIZE);
@@ -184,18 +187,17 @@ static void add_mac_region(phys_addr_t start, unsigned long size) 


static int tboot_setup_sleep(void)

{

	int i;



	tboot->num_mac_regions = 0;



	/* S3 resume code */

	add_mac_region(acpi_wakeup_address, WAKEUP_SIZE);

	for (i = 0; i < e820.nr_map; i++) {

		if ((e820.map[i].type != E820_RAM)

		 && (e820.map[i].type != E820_RESERVED_KERN))

			continue;



#ifdef CONFIG_X86_TRAMPOLINE

	/* AP trampoline code */

	add_mac_region(virt_to_phys(trampoline_base), TRAMPOLINE_SIZE);

#endif



	/* kernel code + data + bss */

	add_mac_region(virt_to_phys(_text), _end - _text);

		add_mac_region(e820.map[i].addr, e820.map[i].size);

	}



	tboot->acpi_sinfo.kernel_s3_resume_vector = acpi_wakeup_address;

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