diff options
| -rw-r--r-- | src/security/vboot/secdata_tpm.c | 46 |
1 files changed, 37 insertions, 9 deletions
diff --git a/src/security/vboot/secdata_tpm.c b/src/security/vboot/secdata_tpm.c index 65d9c83a34..0e14575f61 100644 --- a/src/security/vboot/secdata_tpm.c +++ b/src/security/vboot/secdata_tpm.c @@ -109,13 +109,41 @@ static const TPMA_NV rw_space_attributes = { }; /* - * This policy digest was obtained using TPM2_PolicyPCR - * selecting only PCR_0 with a value of all zeros. + * This policy digest was obtained using TPM2_PolicyOR on 3 digests + * corresponding to a sequence of + * -) TPM2_PolicyCommandCode(TPM_CC_NV_UndefineSpaceSpecial), + * -) TPM2_PolicyPCR(PCR0, <extended_value>). + * where <extended value> is + * 1) all zeros = initial, unextended state: + * - Value to extend to initial PCR0: + * <none> + * - Resulting PCR0: + * 0000000000000000000000000000000000000000000000000000000000000000 + * - Policy digest for PolicyCommandCode + PolicyPCR: + * 4B44FC4192DB5AD7167E0135708FD374890A06BFB56317DF01F24F2226542A3F + * 2) result of extending (SHA1(0x00|0x01|0x00) | 00s to SHA256 size) + * - Value to extend to initial PCR0: + * 62571891215b4efc1ceab744ce59dd0b66ea6f73000000000000000000000000 + * - Resulting PCR0: + * 9F9EA866D3F34FE3A3112AE9CB1FBABC6FFE8CD261D42493BC6842A9E4F93B3D + * - Policy digest for PolicyCommandCode + PolicyPCR: + * CB5C8014E27A5F7586AAE42DB4F9776A977BCBC952CA61E33609DA2B2C329418 + * 3) result of extending (SHA1(0x01|0x01|0x00) | 00s to SHA256 size) + * - Value to extend to initial PCR0: + * 47ec8d98366433dc002e7721c9e37d5067547937000000000000000000000000 + * - Resulting PCR0: + * 2A7580E5DA289546F4D2E0509CC6DE155EA131818954D36D49E027FD42B8C8F8 + * - Policy digest for PolicyCommandCode + PolicyPCR: + * E6EF4F0296AC3EF0F53906480985B1BE8058E0E517E5F74A5B8A415EFE339D87 + * Values #2 and #3 correspond to two forms of recovery mode as extended by + * vb2api_get_pcr_digest(). + * As a result, the digest allows deleting the space with UndefineSpaceSpecial + * at early RO stages (before extending PCR0) or from recovery mode. */ -static 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}; +static const uint8_t pcr0_allowed_policy[] = { + 0x44, 0x44, 0x79, 0x00, 0xCB, 0xB8, 0x3F, 0x5B, 0x15, 0x76, 0x56, + 0x50, 0xEF, 0x96, 0x98, 0x0A, 0x2B, 0x96, 0x6E, 0xA9, 0x09, 0x04, + 0x4A, 0x01, 0xB8, 0x5F, 0xA5, 0x4A, 0x96, 0xFC, 0x59, 0x84}; /* Nothing special in the TPM2 path yet. */ static uint32_t safe_write(uint32_t index, const void *data, uint32_t length) @@ -154,7 +182,7 @@ static uint32_t set_firmware_space(const void *firmware_blob) { return set_space("firmware", FIRMWARE_NV_INDEX, firmware_blob, VB2_SECDATA_FIRMWARE_SIZE, ro_space_attributes, - pcr0_unchanged_policy, sizeof(pcr0_unchanged_policy)); + pcr0_allowed_policy, sizeof(pcr0_allowed_policy)); } static uint32_t set_kernel_space(const void *kernel_blob) @@ -167,8 +195,8 @@ static uint32_t set_mrc_hash_space(uint32_t index, const uint8_t *data) { if (index == MRC_REC_HASH_NV_INDEX) { return set_space("RO MRC Hash", index, data, HASH_NV_SIZE, - ro_space_attributes, pcr0_unchanged_policy, - sizeof(pcr0_unchanged_policy)); + ro_space_attributes, pcr0_allowed_policy, + sizeof(pcr0_allowed_policy)); } else { return set_space("RW MRC Hash", index, data, HASH_NV_SIZE, rw_space_attributes, NULL, 0); |