[coreboot-gerrit] Patch set updated for coreboot: lib/tpm2: do not create all NVRAM spaces with the same set of attributes

[Vadim Bendebury (vbendeb@chromium.org)]

Vadim Bendebury (vbendeb at chromium.org) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/17388

-gerrit

commit 1f87681b269b2fedb54b5fd63a64796af4bc828a
Author: Vadim Bendebury <vbendeb at chromium.org>
Date:   Fri Nov 11 09:36:50 2016 -0800

    lib/tpm2: do not create all NVRAM spaces with the same set of attributes
    
    The TPM spaces created by the RO need have different attributes
    depending on the space's use. The firmware rollback counter and MRC
    hash spaces are created by the RO code and need to be protected at the
    highest level: it should be impossible to delete or modify the space
    once the RO exits, and it is how it is done before this patch.
    
    The rest of the spaces should be possible to modify or recreate even
    after the RO exits. Let's use different set of NVRAM space attributes
    to achieve that, and set the 'pcr0 unchanged' policy only for the
    firmware counter and MRC cache spaces.
    
    The definitions of the attributes can be found in "Trusted Platform
    Module Library Part 2: Structures", Revision 01.16, section "13.2
    TPMA_NV (NV Index Attributes)"
    
    CQ-DEPEND=CL:410127
    BRANCH=none
    BUG=chrome-os-partner:59651
    TEST=verified that the reef system boots fine in both normal and
         recovery modes; using tpmc confirmed that firmware, kernel and
         MRC cache NVRAM spaces are readable in both and writeable only in
         recovery mode.
    
    Change-Id: I1a1d2459f56ec929c9a92b39175888b8d1bcda55
    Signed-off-by: Vadim Bendebury <vbendeb at chromium.org>
---
 src/lib/tpm2_tlcl.c | 64 +++++++++++++++++++++++++++++++++++------------------
 1 file changed, 42 insertions(+), 22 deletions(-)

diff --git a/src/lib/tpm2_tlcl.c b/src/lib/tpm2_tlcl.c
index adc4c2e..457e874 100644
--- a/src/lib/tpm2_tlcl.c
+++ b/src/lib/tpm2_tlcl.c
@@ -4,6 +4,7 @@
  * found in the LICENSE file.
  */
 
+#include <antirollback.h>
 #include <arch/early_variables.h>
 #include <console/console.h>
 #include <endian.h>
@@ -299,14 +300,23 @@ uint32_t tlcl_define_space(uint32_t space_index, size_t space_size)
 	struct tpm2_nv_define_space_cmd nvds_cmd;
 	struct tpm2_response *response;
 	/*
-	 * This policy digest was obtained using TPM2_PolicyPCR selecting only
-	 * PCR_0 with a value of all zeros.
+	 * Different sets of NVRAM space attributes apply to the "ro" spaces,
+	 * i.e. those which should not be possible to delete or modify once
+	 * the RO exits, and the rest of the NVRAM spaces.
 	 */
-	const uint8_t pcr0_unchanged_policy[] = {
-		0x09, 0x93, 0x3C, 0xCE, 0xEB, 0xB4, 0x41, 0x11,
-		0x18, 0x81, 0x1D, 0xD4, 0x47, 0x78, 0x80, 0x08,
-		0x88, 0x86, 0x62, 0x2D, 0xD7, 0x79, 0x94, 0x46,
-		0x62, 0x26, 0x68, 0x8E, 0xEE, 0xE6, 0x6A, 0xA1
+	const TPMA_NV ro_space_attributes = {
+		.TPMA_NV_PPWRITE = 1,
+		.TPMA_NV_AUTHREAD = 1,
+		.TPMA_NV_PPREAD = 1,
+		.TPMA_NV_PLATFORMCREATE = 1,
+		.TPMA_NV_WRITE_STCLEAR = 1,
+		.TPMA_NV_POLICY_DELETE = 1,
+	};
+	const TPMA_NV default_space_attributes = {
+		.TPMA_NV_PPWRITE = 1,
+		.TPMA_NV_AUTHREAD = 1,
+		.TPMA_NV_PPREAD = 1,
+		.TPMA_NV_PLATFORMCREATE = 1,
 	};
 
 	/* Prepare the define space command structure. */
@@ -316,21 +326,31 @@ uint32_t tlcl_define_space(uint32_t space_index, size_t space_size)
 	nvds_cmd.publicInfo.nvIndex = HR_NV_INDEX + space_index;
 	nvds_cmd.publicInfo.nameAlg = TPM_ALG_SHA256;
 
-	/* Attributes common for all NVRAM spaces used by firmware. */
-	nvds_cmd.publicInfo.attributes.TPMA_NV_PPWRITE = 1;
-	nvds_cmd.publicInfo.attributes.TPMA_NV_AUTHREAD = 1;
-	nvds_cmd.publicInfo.attributes.TPMA_NV_PPREAD = 1;
-	nvds_cmd.publicInfo.attributes.TPMA_NV_PLATFORMCREATE = 1;
-	nvds_cmd.publicInfo.attributes.TPMA_NV_WRITE_STCLEAR = 1;
-	nvds_cmd.publicInfo.attributes.TPMA_NV_POLICY_DELETE = 1;
-
-	/*
-	 * Use policy digest based on default pcr0 value. This makes sure that
-	 * the space can not be deleted as soon as PCR0 value has been
-	 * extended from default.
-	 */
-	nvds_cmd.publicInfo.authPolicy.t.buffer = pcr0_unchanged_policy;
-	nvds_cmd.publicInfo.authPolicy.t.size = sizeof(pcr0_unchanged_policy);
+	/* RO only NV spaces should be impossible to destroy. */
+	if ((space_index == FIRMWARE_NV_INDEX) ||
+	    (space_index == REC_HASH_NV_INDEX)) {
+		/*
+		 * This policy digest was obtained using TPM2_PolicyPCR
+		 * selecting only PCR_0 with a value of all zeros.
+		 */
+		const uint8_t pcr0_unchanged_policy[] = {
+			0x09, 0x93, 0x3C, 0xCE, 0xEB, 0xB4, 0x41, 0x11,
+			0x18, 0x81, 0x1D, 0xD4, 0x47, 0x78, 0x80, 0x08,
+			0x88, 0x86, 0x62, 0x2D, 0xD7, 0x79, 0x94, 0x46,
+			0x62, 0x26, 0x68, 0x8E, 0xEE, 0xE6, 0x6A, 0xA1
+		};
+
+		nvds_cmd.publicInfo.attributes = ro_space_attributes;
+		/*
+		 * Use policy digest based on default pcr0 value. This makes
+		 * sure that the space can not be deleted as soon as PCR0
+		 * value has been extended from default.
+		 */
+		nvds_cmd.publicInfo.authPolicy.t.buffer = pcr0_unchanged_policy;
+		nvds_cmd.publicInfo.authPolicy.t.size = sizeof(pcr0_unchanged_policy);
+	} else {
+		nvds_cmd.publicInfo.attributes = default_space_attributes;
+	}
 
 	response = tpm_process_command(TPM2_NV_DefineSpace, &nvds_cmd);
 	printk(BIOS_INFO, "%s: response is %x\n",