[coreboot-gerrit] New patch to review 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 1e78d975f720e148001353d86eb3b343168275a0
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 space is
    created be the RO code and needs to be protected at the highest level
    - it should be impossible to delete or modify the space once the RO
    exits, 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.
    
    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 both firmware kernel
         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 | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/lib/tpm2_tlcl.c b/src/lib/tpm2_tlcl.c
index ecf0db6..6970f54 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>
@@ -292,6 +293,22 @@ 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;
+	const TPMA_NV firmware_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,
+	};
+
 	/*
 	 * This policy digest was obtained using TPM2_PolicyPCR selecting only
 	 * PCR_0 with a value of all zeros.
@@ -310,13 +327,11 @@ 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;
+	/* Firmware NV index space should be impossible to destroy. */
+	if (space_index == FIRMWARE_NV_INDEX)
+		nvds_cmd.publicInfo.attributes = firmware_space_attributes;
+	else
+		nvds_cmd.publicInfo.attributes = default_space_attributes;
 
 	/*
 	 * Use policy digest based on default pcr0 value. This makes sure that