GNUBoot
/
coreboot-kgpe-d16
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

coreboot: check Cr50 PM mode on normal boot 

Under some scenarios the key ladder on the Cr50 can get disabled.  If
this state is detected, trigger a reboot of the Cr50 to restore full
TPM functionality.

BUG=b:121463033
BRANCH=none
TEST=Built coreboot on sarien and grunt platforms.
TEST=Ran 'gsctool -a -m disable' and reboot. Verified coreboot sends
VENDOR_CC_IMMEDIATE_RESET command to Cr50 and that the Cr50 resets and
then the platform boots normally.
TEST=Performed Cr50 rollback to 0.0.22 which does not support the
VENDOR_CC_TPM_MODE command, confirmed that platform boots normally and
the coreboot log captures the unsupported command.
Tested-by: Keith Short <keithshort@chromium.org>

Change-Id: I70e012efaf1079d43890e909bc6b5015bef6835a
Signed-off-by: Keith Short <keithshort@chromium.org>
Reviewed-on: https://review.coreboot.org/c/31260
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
This commit is contained in:
Keith Short 2019-02-05 16:15:10 -07:00 committed by Patrick Georgi
parent 91be00ef1b
commit e0f3400547
9 changed files with 247 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
src/include/elog.h
View File

@ -223,6 +223,9 @@ struct elog_event_mem_cache_update {
#define ELOG_SLEEP_PENDING_PM1_WAKE 0x01
#define ELOG_SLEEP_PENDING_GPE0_WAKE 0x02
/* Cr50 reset to enable TPM */
#define ELOG_TYPE_CR50_NEED_RESET 0xb2
struct elog_event_extended_event {
u8 event_type;
u32 event_complement;

2
src/mainboard/google/sarien/chromeos.c
View File

@ -115,7 +115,7 @@ int get_lid_switch(void)
return 1;
}
void mainboard_cr50_update_reset(void)
void mainboard_prepare_cr50_reset(void)
{
#if ENV_RAMSTAGE
/* Ensure system powers up after CR50 reset */

24
src/security/tpm/tss/tcg-2.0/tss_marshaling.c
View File

@ -266,6 +266,14 @@ static int marshal_cr50_vendor_command(struct obuf *ob, void *command_body)
uint16_t *sub_command = command_body;
switch (*sub_command) {
case TPM2_CR50_SUB_CMD_IMMEDIATE_RESET:
/* The 16-bit timeout parameter is optional for the
* IMMEDIATE_RESET command. However in coreboot, the timeout
* parameter must be specified.
*/
rc |= obuf_write_be16(ob, sub_command[0]);
rc |= obuf_write_be16(ob, sub_command[1]);
break;
case TPM2_CR50_SUB_CMD_NVMEM_ENABLE_COMMITS:
rc |= obuf_write_be16(ob, *sub_command);
break;
@ -276,6 +284,18 @@ static int marshal_cr50_vendor_command(struct obuf *ob, void *command_body)
case TPM2_CR50_SUB_CMD_GET_REC_BTN:
rc |= obuf_write_be16(ob, *sub_command);
break;
case TPM2_CR50_SUB_CMD_TPM_MODE:
/* The Cr50 TPM_MODE command supports an optional parameter.
* When the parameter is present the Cr50 will attempt to change
* the TPM state (enable or disable) and returns the new state
* in the response. When the parameter is absent, the Cr50
* returns the current TPM state.
*
* coreboot currently only uses the TPM get capability and does
* not set a new TPM state with the Cr50.
*/
rc |= obuf_write_be16(ob, *sub_command);
break;
default:
/* Unsupported subcommand. */
printk(BIOS_WARNING, "Unsupported cr50 subcommand: 0x%04x\n",
@ -471,12 +491,16 @@ static int unmarshal_vendor_command(struct ibuf *ib,
return -1;
switch (vcr->vc_subcommand) {
case TPM2_CR50_SUB_CMD_IMMEDIATE_RESET:
break;
case TPM2_CR50_SUB_CMD_NVMEM_ENABLE_COMMITS:
break;
case TPM2_CR50_SUB_CMD_TURN_UPDATE_ON:
return ibuf_read_be8(ib, &vcr->num_restored_headers);
case TPM2_CR50_SUB_CMD_GET_REC_BTN:
return ibuf_read_be8(ib, &vcr->recovery_button_state);
case TPM2_CR50_SUB_CMD_TPM_MODE:
return ibuf_read_be8(ib, &vcr->tpm_mode);
default:
printk(BIOS_ERR,
"%s:%d - unsupported vendor command %#04x!\n",

1
src/security/tpm/tss/tcg-2.0/tss_structures.h
View File

@ -298,6 +298,7 @@ struct vendor_command_response {
union {
uint8_t num_restored_headers;
uint8_t recovery_button_state;
uint8_t tpm_mode;
};
};

65
src/security/tpm/tss/vendor/cr50/cr50.c vendored
View File

@ -26,7 +26,7 @@ uint32_t tlcl_cr50_enable_nvcommits(void)
if (response == NULL || (response && response->hdr.tpm_code)) {
if (response)
printk(BIOS_INFO, "%s: failed %x\n", __func__,
response->hdr.tpm_code);
response->hdr.tpm_code);
else
printk(BIOS_INFO, "%s: failed\n", __func__);
return TPM_E_IOERROR;
@ -47,7 +47,7 @@ uint32_t tlcl_cr50_enable_update(uint16_t timeout_ms,
response = tpm_process_command(TPM2_CR50_VENDOR_COMMAND, command_body);
if (!response || response->hdr.tpm_code)
return TPM_E_INTERNAL_INCONSISTENCY;
return TPM_E_IOERROR;
*num_restored_headers = response->vcr.num_restored_headers;
return TPM_SUCCESS;
@ -63,8 +63,67 @@ uint32_t tlcl_cr50_get_recovery_button(uint8_t *recovery_button_state)
response = tpm_process_command(TPM2_CR50_VENDOR_COMMAND, &sub_command);
if (!response || response->hdr.tpm_code)
return TPM_E_INTERNAL_INCONSISTENCY;
return TPM_E_IOERROR;
*recovery_button_state = response->vcr.recovery_button_state;
return TPM_SUCCESS;
}
uint32_t tlcl_cr50_get_tpm_mode(uint8_t *tpm_mode)
{
struct tpm2_response *response;
uint16_t mode_command = TPM2_CR50_SUB_CMD_TPM_MODE;
*tpm_mode = TPM_MODE_INVALID;
printk(BIOS_INFO, "Reading cr50 TPM mode\n");
response = tpm_process_command(TPM2_CR50_VENDOR_COMMAND, &mode_command);
if (!response)
return TPM_E_IOERROR;
if (response->hdr.tpm_code == VENDOR_RC_INTERNAL_ERROR) {
/*
* The Cr50 returns VENDOR_RC_INTERNAL_ERROR iff the key ladder
* is disabled. The Cr50 requires a reboot to re-enable the key
* ladder.
*/
return TPM_E_MUST_REBOOT;
}
if (response->hdr.tpm_code == VENDOR_RC_NO_SUCH_COMMAND) {
/*
* Explicitly inform caller when command is not supported
*/
return TPM_E_NO_SUCH_COMMAND;
}
if (response->hdr.tpm_code) {
/* Unexpected return code from Cr50 */
return TPM_E_IOERROR;
}
/* TPM command completed without error */
*tpm_mode = response->vcr.tpm_mode;
return TPM_SUCCESS;
}
uint32_t tlcl_cr50_immediate_reset(uint16_t timeout_ms)
{
struct tpm2_response *response;
uint16_t reset_command_body[] = {
TPM2_CR50_SUB_CMD_IMMEDIATE_RESET, timeout_ms};
/*
* Issue an immediate reset to the Cr50.
*/
printk(BIOS_INFO, "Issuing cr50 reset\n");
response = tpm_process_command(TPM2_CR50_VENDOR_COMMAND,
&reset_command_body);
if (!response)
return TPM_E_IOERROR;
return TPM_SUCCESS;
}

48
src/security/tpm/tss/vendor/cr50/cr50.h vendored
View File

@ -23,9 +23,35 @@
to extending generically because the marshaling code is assuming all
knowledge of all commands. */
#define TPM2_CR50_VENDOR_COMMAND ((TPM_CC)(TPM_CC_VENDOR_BIT_MASK | 0))
#define TPM2_CR50_SUB_CMD_IMMEDIATE_RESET (19)
#define TPM2_CR50_SUB_CMD_NVMEM_ENABLE_COMMITS (21)
#define TPM2_CR50_SUB_CMD_TURN_UPDATE_ON (24)
#define TPM2_CR50_SUB_CMD_GET_REC_BTN (29)
#define TPM2_CR50_SUB_CMD_TPM_MODE (40)
/* Cr50 vendor-specific error codes. */
#define VENDOR_RC_ERR 0x00000500
enum cr50_vendor_rc {
VENDOR_RC_INTERNAL_ERROR = (VENDOR_RC_ERR | 6),
VENDOR_RC_NO_SUCH_COMMAND = (VENDOR_RC_ERR | 127),
};
enum cr50_tpm_mode {
/*
* Default state: TPM is enabled, and may be set to either
* TPM_MODE_ENABLED or TPM_MODE_DISABLED.
*/
TPM_MODE_ENABLED_TENTATIVE = 0,
/* TPM is enabled, and mode may not be changed. */
TPM_MODE_ENABLED = 1,
/* TPM is disabled, and mode may not be changed. */
TPM_MODE_DISABLED = 2,
TPM_MODE_INVALID,
};
/**
* CR50 specific tpm command to enable nvmem commits before internal timeout
@ -53,4 +79,26 @@ uint32_t tlcl_cr50_enable_update(uint16_t timeout_ms,
*/
uint32_t tlcl_cr50_get_recovery_button(uint8_t *recovery_button_state);
/**
* CR50 specific TPM command sequence to query the current TPM mode.
*
* Returns TPM_SUCCESS if TPM mode command completed, the Cr50 does not need a
* reboot, and the tpm_mode parameter is set to the current TPM mode.
* Returns TPM_E_MUST_REBOOT if TPM mode command completed, but the Cr50
* requires a reboot.
* Returns TPM_E_NO_SUCH_COMMAND if the Cr50 does not support the command.
* Other returns value indicate a failure accessing the TPM.
*/
uint32_t tlcl_cr50_get_tpm_mode(uint8_t *tpm_mode);
/**
* CR50 specific TPM command sequence to trigger an immediate reset to the Cr50
* device after the specified timeout in milliseconds. A timeout of zero means
* "IMMEDIATE REBOOT".
*
* Return value indicates success or failure of accessing the TPM.
*/
uint32_t tlcl_cr50_immediate_reset(uint16_t timeout_ms);
#endif /* CR50_TSS_STRUCTURES_H_ */

1
src/security/tpm/tss_errors.h
View File

@ -42,5 +42,6 @@
#define TPM_E_NV_DEFINED ((uint32_t)0x0000500b) /* vboot local */
#define TPM_E_INVALID_ARG ((uint32_t)0x0000500c)
#define TPM_E_HASH_ERROR ((uint32_t)0x0000500d)
#define TPM_E_NO_SUCH_COMMAND ((uint32_t)0x0000500e)
#endif /* TSS_ERRORS_H_ */

7
src/vendorcode/google/chromeos/chromeos.h
View File

@ -33,8 +33,11 @@ static inline void mark_watchdog_tombstone(void) { return; }
static inline void reboot_from_watchdog(void) { return; }
#endif /* CONFIG_CHROMEOS */
/* Defined as weak function in cr50_enable_update.c */
void mainboard_cr50_update_reset(void);
/**
* Perform any platform specific actions required prior to resetting the Cr50.
* Defined as weak function in cr50_enable_update.c
*/
void mainboard_prepare_cr50_reset(void);
struct romstage_handoff;

116
src/vendorcode/google/chromeos/cr50_enable_update.c
View File

@ -23,7 +23,75 @@
#include <security/vboot/vboot_common.h>
#include <vendorcode/google/chromeos/chromeos.h>
void __weak mainboard_cr50_update_reset(void) {}
#define C50_RESET_DELAY_MS 1000
void __weak mainboard_prepare_cr50_reset(void) {}
/**
* Check if the Cr50 TPM state requires a chip reset of the Cr50 device.
*
* Returns 0 if the Cr50 TPM state is good or if the TPM_MODE command is
* unsupported. Returns 1 if the Cr50 was reset.
*/
static int cr50_reset_if_needed(uint16_t timeout_ms)
{
int ret;
int cr50_must_reset = 0;
uint8_t tpm_mode;
ret = tlcl_cr50_get_tpm_mode(&tpm_mode);
if (ret == TPM_E_NO_SUCH_COMMAND) {
printk(BIOS_INFO,
"Cr50 does not support TPM mode command\n");
/* Older Cr50 firmware, assume no Cr50 reset is required */
return 0;
}
if (ret == TPM_E_MUST_REBOOT) {
/*
* Cr50 indicated a reboot is required to restore TPM
* functionality.
*/
cr50_must_reset = 1;
} else if (ret != TPM_SUCCESS) {
/* TPM command failed, continue booting. */
printk(BIOS_ERR,
"ERROR: Attempt to get CR50 TPM mode failed: %x\n", ret);
return 0;
}
/* If the TPM mode is not enabled-tentative, then the TPM mode is locked
* and cannot be changed. Perform a Cr50 reset because vboot may need
* to disable TPM as part of booting an untrusted OS.
*
* This is not an expected state, as the Cr50 always sets the TPM mode
* to TPM_MODE_ENABLED_TENTATIVE during any TPM reset action.
*/
if (tpm_mode != TPM_MODE_ENABLED_TENTATIVE) {
printk(BIOS_NOTICE,
"NOTICE: Unexpected Cr50 TPM mode (%d). "
"A Cr50 reset is required.\n", tpm_mode);
cr50_must_reset = 1;
}
/* If TPM state is okay, no reset needed. */
if (!cr50_must_reset)
return 0;
ret = tlcl_cr50_immediate_reset(timeout_ms);
if (ret != TPM_SUCCESS) {
/* TPM command failed, continue booting. */
printk(BIOS_ERR,
"ERROR: Attempt to reset CR50 failed: %x\n",
ret);
return 0;
}
/* Cr50 is about to be reset, caller needs to prepare */
return 1;
}
static void enable_update(void *unused)
{
@ -37,34 +105,54 @@ static void enable_update(void *unused)
ret = tlcl_lib_init();
if (ret != VB2_SUCCESS) {
printk(BIOS_ERR, "tlcl_lib_init() failed for CR50 update: %x\n",
ret);
printk(BIOS_ERR,
"ERROR: tlcl_lib_init() failed for CR50 update: %x\n",
ret);
return;
}
/* Reboot in 1000 ms if necessary. */
ret = tlcl_cr50_enable_update(1000, &num_restored_headers);
ret = tlcl_cr50_enable_update(C50_RESET_DELAY_MS,
&num_restored_headers);
if (ret != TPM_SUCCESS) {
printk(BIOS_ERR, "Attempt to enable CR50 update failed: %x\n",
ret);
printk(BIOS_ERR,
"ERROR: Attempt to enable CR50 update failed: %x\n",
ret);
return;
}
/* If no headers were restored there is no reset forthcoming. */
if (!num_restored_headers)
return;
if (!num_restored_headers) {
/* If no headers were restored there is no reset forthcoming due
* to a Cr50 firmware update. Also check if the Cr50 TPM mode
* requires a reset.
*
* TODO: to eliminate a TPM command during every boot, the
* TURN_UPDATE_ON command could be enhanced/replaced in the Cr50
* firmware to perform the TPM mode/key-ladder check in addition
* to the FW version check.
*/
/*
* If the Cr50 was not reset, continue booting.
*/
if (!cr50_reset_if_needed(C50_RESET_DELAY_MS))
return;
printk(BIOS_INFO, "Waiting for CR50 reset to enable TPM.\n");
elog_add_event(ELOG_TYPE_CR50_NEED_RESET);
} else {
printk(BIOS_INFO,
"Waiting for CR50 reset to pick up update.\n");
elog_add_event(ELOG_TYPE_CR50_UPDATE);
}
/* Give mainboard a chance to take action */
mainboard_cr50_update_reset();
elog_add_event(ELOG_TYPE_CR50_UPDATE);
mainboard_prepare_cr50_reset();
/* clear current post code avoid chatty eventlog on subsequent boot*/
post_code(0);
printk(BIOS_INFO, "Waiting for CR50 reset to pick up update.\n");
if (IS_ENABLED(CONFIG_POWER_OFF_ON_CR50_UPDATE))
poweroff();
halt();