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tpm: Allow disabling platform hierarchy with TPM2 

With TPM2 we don't actually lock the TPM once verified boot is finished.
Instead we disable the platform hierarchy which serves the same purpose.
Add an implementation of this so we can safely boot into the kernel.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
This commit is contained in:
Simon Glass 2021-02-06 14:23:42 -07:00 committed by Tom Rini
parent 7785bc1d5f
commit 63af92e837
2 changed files with 48 additions and 0 deletions
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13
include/tpm-v2.h
View File

@ -237,6 +237,7 @@ enum tpm2_handles {
enum tpm2_command_codes {
TPM2_CC_STARTUP = 0x0144,
TPM2_CC_SELF_TEST = 0x0143,
TPM2_CC_HIER_CONTROL = 0x0121,
TPM2_CC_CLEAR = 0x0126,
TPM2_CC_CLEARCONTROL = 0x0127,
TPM2_CC_HIERCHANGEAUTH = 0x0129,
@ -274,6 +275,7 @@ enum tpm2_return_codes {
TPM2_RC_COMMAND_CODE = TPM2_RC_VER1 + 0x0043,
TPM2_RC_AUTHSIZE = TPM2_RC_VER1 + 0x0044,
TPM2_RC_AUTH_CONTEXT = TPM2_RC_VER1 + 0x0045,
TPM2_RC_NV_DEFINED = TPM2_RC_VER1 + 0x004c,
TPM2_RC_NEEDS_TEST = TPM2_RC_VER1 + 0x0053,
TPM2_RC_WARN = 0x0900,
TPM2_RC_TESTING = TPM2_RC_WARN + 0x000A,
@ -584,4 +586,15 @@ u32 tpm2_get_random(struct udevice *dev, void *data, u32 count);
*/
u32 tpm2_write_lock(struct udevice *dev, u32 index);
/**
* Disable access to any platform data
*
* This can be called to close off access to the firmware data in the data,
* before calling the kernel.
*
* @dev TPM device
* @return code of the operation
*/
u32 tpm2_disable_platform_hierarchy(struct udevice *dev);
#endif /* __TPM_V2_H */

35
lib/tpm-v2.c
View File

@ -624,3 +624,38 @@ u32 tpm2_write_lock(struct udevice *dev, u32 index)
return tpm_sendrecv_command(dev, command_v2, NULL, NULL);
}
u32 tpm2_disable_platform_hierarchy(struct udevice *dev)
{
struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
u8 command_v2[COMMAND_BUFFER_SIZE] = {
/* header 10 bytes */
tpm_u16(TPM2_ST_SESSIONS), /* TAG */
tpm_u32(10 + 4 + 13 + 5), /* Length */
tpm_u32(TPM2_CC_HIER_CONTROL), /* Command code */
/* 4 bytes */
tpm_u32(TPM2_RH_PLATFORM), /* Primary platform seed */
/* session header 9 bytes */
tpm_u32(9), /* Header size */
tpm_u32(TPM2_RS_PW), /* Password authorisation */
tpm_u16(0), /* nonce_size */
0, /* session_attrs */
tpm_u16(0), /* auth_size */
/* payload 5 bytes */
tpm_u32(TPM2_RH_PLATFORM), /* Hierarchy to disable */
0, /* 0=disable */
};
int ret;
ret = tpm_sendrecv_command(dev, command_v2, NULL, NULL);
log_info("ret=%s, %x\n", dev->name, ret);
if (ret)
return ret;
priv->plat_hier_disabled = true;
return 0;
}