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authorVadim Bendebury <vbendeb@chromium.org>2016-11-14 16:36:26 -0800
committerVadim Bendebury <vbendeb@chromium.org>2016-11-16 02:16:11 +0100
commit3883701d5a91f6431d4579734c022f7748249ec1 (patch)
tree06493229e2f1d42aba0ea7f866953ff3473b3500
parentaf8ae93172bd793787dc3a9b81695905c1899d1f (diff)
downloadcoreboot-3883701d5a91f6431d4579734c022f7748249ec1.tar.xz
vboot: make TPM factory init sequence more robust.
Currently the code considers the absence of the NVRAM firmware rollback space a a trigger for invoking the TPM factory initialization sequence. Note that the kernel rollback and MRC cache hash spaces are created after the firmware rollback space. This opens an ever so narrow window of opportunity for bricking the device, in case a startup is interrupted after firmware space has been created, but before kernel and MRC hash spaces are created. The suggested solution is to create the firmware space last, and to allow for kernel and MRC cache spaces to exist during TPM factory initialization. BRANCH=none BUG=chrome-os-partner:59654 TEST=odified the code not to create the firmware space, wiped out the TPM NVRAM and booted the device. Observed it create kernel and MRC cache spaces on the first run, and then reporting return code 0x14c for already existing spaces on the following restarts. Verified that the device boots fine in normal and recovery modes and TPM NVRAM spaces are writeable in recovery mode. Change-Id: Id0e772448d6af1340e800ec3b78ec67913aa6289 Signed-off-by: Vadim Bendebury <vbendeb@chromium.org> Reviewed-on: https://review.coreboot.org/17398 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins)
-rw-r--r--src/vboot/secdata_tpm.c44
1 files changed, 33 insertions, 11 deletions
diff --git a/src/vboot/secdata_tpm.c b/src/vboot/secdata_tpm.c
index 357d6e3fb7..4c1e128797 100644
--- a/src/vboot/secdata_tpm.c
+++ b/src/vboot/secdata_tpm.c
@@ -150,31 +150,53 @@ static uint32_t set_firmware_space(const void *firmware_blob)
static uint32_t set_kernel_space(const void *kernel_blob)
{
- RETURN_ON_FAILURE(tlcl_define_space(KERNEL_NV_INDEX,
- sizeof(secdata_kernel)));
- RETURN_ON_FAILURE(safe_write(KERNEL_NV_INDEX, kernel_blob,
- sizeof(secdata_kernel)));
- return TPM_SUCCESS;
+ uint32_t rv;
+
+ rv = tlcl_define_space(KERNEL_NV_INDEX, sizeof(secdata_kernel));
+ if (rv == TPM_E_NV_DEFINED) {
+ VBDEBUG("%s: kernel space already exists\n", __func__);
+ return TPM_SUCCESS;
+ }
+
+ if (rv != TPM_SUCCESS)
+ return rv;
+
+ return safe_write(KERNEL_NV_INDEX, kernel_blob, sizeof(secdata_kernel));
}
static uint32_t set_rec_hash_space(const uint8_t *data)
{
- RETURN_ON_FAILURE(tlcl_define_space(REC_HASH_NV_INDEX,
- REC_HASH_NV_SIZE));
- RETURN_ON_FAILURE(safe_write(REC_HASH_NV_INDEX, data,
- REC_HASH_NV_SIZE));
- return TPM_SUCCESS;
+ uint32_t rv;
+
+ rv = tlcl_define_space(REC_HASH_NV_INDEX, REC_HASH_NV_SIZE);
+ if (rv == TPM_E_NV_DEFINED) {
+ VBDEBUG("%s: MRC Hash space already exists\n", __func__);
+ return TPM_SUCCESS;
+ }
+
+ if (rv != TPM_SUCCESS)
+ return rv;
+
+ return safe_write(REC_HASH_NV_INDEX, data, REC_HASH_NV_SIZE);
}
static uint32_t _factory_initialize_tpm(struct vb2_context *ctx)
{
RETURN_ON_FAILURE(tlcl_force_clear());
- RETURN_ON_FAILURE(set_firmware_space(ctx->secdata));
+
+ /*
+ * Of all NVRAM spaces defined by this function the firmware space
+ * must be defined last, because its existence is considered an
+ * indication that TPM factory initialization was successfully
+ * completed.
+ */
RETURN_ON_FAILURE(set_kernel_space(secdata_kernel));
if (IS_ENABLED(CONFIG_VBOOT_HAS_REC_HASH_SPACE))
RETURN_ON_FAILURE(set_rec_hash_space(rec_hash_data));
+ RETURN_ON_FAILURE(set_firmware_space(ctx->secdata));
+
return TPM_SUCCESS;
}