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-rw-r--r--hal.h3
-rw-r--r--ks_flash.c4
-rw-r--r--masterkey.c146
-rw-r--r--masterkey.h19
4 files changed, 101 insertions, 71 deletions
diff --git a/hal.h b/hal.h
index 776acac..04dab48 100644
--- a/hal.h
+++ b/hal.h
@@ -139,6 +139,9 @@
DEFINE_HAL_ERROR(HAL_ERROR_RPC_PACKET_OVERFLOW, "RPC packet overflow") \
DEFINE_HAL_ERROR(HAL_ERROR_RPC_BAD_FUNCTION, "Bad RPC function number") \
DEFINE_HAL_ERROR(HAL_ERROR_KEY_NAME_TOO_LONG, "Key name too long") \
+ DEFINE_HAL_ERROR(HAL_ERROR_MASTERKEY_NOT_SET, "Master key (Key Encryption Key) not set") \
+ DEFINE_HAL_ERROR(HAL_ERROR_MASTERKEY_FAIL, "Master key generic failure") \
+ DEFINE_HAL_ERROR(HAL_ERROR_MASTERKEY_BAD_LENGTH, "Master key of unacceptable length") \
END_OF_HAL_ERROR_LIST
/* Marker to forestall silly line continuation errors */
diff --git a/ks_flash.c b/ks_flash.c
index 036e72e..159df5b 100644
--- a/ks_flash.c
+++ b/ks_flash.c
@@ -324,11 +324,11 @@ hal_error_t hal_ks_get_kek(uint8_t *kek,
(kek_max < bitsToBytes(256)) ? bitsToBytes(192) :
bitsToBytes(256));
- if (masterkey_volatile_read(kek, len) == HSM_MASTERKEY_SET) {
+ if (masterkey_volatile_read(kek, len) == LIBHAL_OK) {
*kek_len = len;
return LIBHAL_OK;
}
- if (masterkey_flash_read(kek, len) == HSM_MASTERKEY_SET) {
+ if (masterkey_flash_read(kek, len) == LIBHAL_OK) {
*kek_len = len;
return LIBHAL_OK;
}
diff --git a/masterkey.c b/masterkey.c
index cc9a62f..6425515 100644
--- a/masterkey.c
+++ b/masterkey.c
@@ -32,6 +32,23 @@
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
+/*
+ * Code to load the Master key (Key Encryption Key) from either the volatile MKM
+ * (by asking the FPGA to provide it, using the mkmif) or from the last sector in
+ * the keystore flash.
+ *
+ * Storing the master key in flash is a pretty Bad Idea, but since the Alpha board
+ * doesn't have a battery mounted (only pin headers for attaching one), it might
+ * help in non-production use where one doesn't have tamper protection anyways.
+ *
+ * For production use on the Alpha, one option is to have the Master Key on paper
+ * and enter it into volatile RAM after each power on.
+ *
+ * In both volatile memory and flash, the data is stored as a 32 bit status to
+ * know if the memory is initialized or not, followed by 32 bytes (256 bits) of
+ * Master Key.
+ */
+
#define HAL_OK CMIS_HAL_OK
#include "stm-init.h"
#include "stm-keystore.h"
@@ -49,11 +66,18 @@ static int volatile_init = 0, flash_init = 0;
static const hal_core_t *core = NULL;
#define MKM_VOLATILE_STATUS_ADDRESS 0
-#define SCLK_DIV 0x20
+#define MKM_VOLATILE_SCLK_DIV 0x20
#define MKM_FLASH_STATUS_ADDRESS (KEYSTORE_SECTOR_SIZE * (KEYSTORE_NUM_SECTORS - 1))
-#define MKM_FLASH_STATUS_IN_USE 0x0000ffff
#define KEK_LENGTH (256 / 8)
+/* Match uninitialized flash for the "not set" value.
+ * Leave some bits at 1 for the "set" value to allow
+ * for adding more values later, if needed.
+ */
+#define MKM_STATUS_NOT_SET 0xffffffff
+#define MKM_STATUS_SET 0x0000ffff
+#define MKM_STATUS_ERASED 0x00000000
+
hal_error_t masterkey_volatile_init()
{
@@ -66,17 +90,21 @@ hal_error_t masterkey_volatile_init()
}
err =
- hal_mkmif_set_clockspeed(core, SCLK_DIV) ||
+ hal_mkmif_set_clockspeed(core, MKM_VOLATILE_SCLK_DIV) ||
hal_mkmif_init(core) ||
hal_mkmif_read_word(core, MKM_VOLATILE_STATUS_ADDRESS, &status);
if (err != LIBHAL_OK) return err;
- if (status != HSM_MASTERKEY_SET &&
- status != HSM_MASTERKEY_NOT_SET) {
- if ((err = hal_mkmif_write_word(core, MKM_VOLATILE_STATUS_ADDRESS, HSM_MASTERKEY_NOT_SET)) != LIBHAL_OK) {
- return err;
- }
+ if (status != MKM_STATUS_SET && status != MKM_STATUS_NOT_SET) {
+ /* XXX Something is a bit fishy here. If we just write the status word, it reads back wrong sometimes,
+ * while if we write the full buf too it is consistently right afterwards.
+ */
+ uint8_t buf[KEK_LENGTH] = {0};
+ err =
+ hal_mkmif_write(core, MKM_VOLATILE_STATUS_ADDRESS + 4, buf, sizeof(buf)) ||
+ hal_mkmif_write_word(core, MKM_VOLATILE_STATUS_ADDRESS, MKM_STATUS_NOT_SET);
+ if (err != LIBHAL_OK) return err;
}
volatile_init = 1;
@@ -84,71 +112,68 @@ hal_error_t masterkey_volatile_init()
return LIBHAL_OK;
}
-masterkey_status_t masterkey_volatile_read(uint8_t *buf, size_t len)
+hal_error_t masterkey_volatile_read(uint8_t *buf, size_t len)
{
hal_error_t err;
uint32_t status;
+ if (len && len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH;
+
err =
masterkey_volatile_init() ||
hal_mkmif_read_word(core, MKM_VOLATILE_STATUS_ADDRESS, &status);
- if (err != LIBHAL_OK) return HSM_MASTERKEY_FAIL;
+ if (err != LIBHAL_OK) return err;
- if (buf != NULL && status == HSM_MASTERKEY_SET) {
- if ((err = hal_mkmif_read(core, MKM_VOLATILE_STATUS_ADDRESS + 4, buf, len)) == LIBHAL_OK) {
- return HSM_MASTERKEY_SET;
+ if (buf != NULL && len) {
+ /* Don't return the random bytes in the RAM memory in case it isn't initialized.
+ * Or maybe we should fill the buffer with proper random data in that case... hmm.
+ */
+ if (status == MKM_STATUS_SET) {
+ if ((err = hal_mkmif_read(core, MKM_VOLATILE_STATUS_ADDRESS + 4, buf, len)) != LIBHAL_OK) {
+ return err;
+ }
+ } else {
+ memset(buf, 0x0, len);
}
}
- if (status == HSM_MASTERKEY_SET || status == HSM_MASTERKEY_NOT_SET) {
- return (masterkey_status_t) status;
- }
+ if (status == MKM_STATUS_SET) return LIBHAL_OK;
+ if (status == MKM_STATUS_NOT_SET) return HAL_ERROR_MASTERKEY_NOT_SET;
- return HSM_MASTERKEY_FAIL;
+ return HAL_ERROR_MASTERKEY_FAIL;
}
-masterkey_status_t masterkey_volatile_write(uint8_t *buf, size_t len)
+hal_error_t masterkey_volatile_write(uint8_t *buf, size_t len)
{
hal_error_t err;
- if (len != KEK_LENGTH) return HSM_MASTERKEY_FAIL;
- if (! buf) return HSM_MASTERKEY_FAIL;
+ if (len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH;
+ if (! buf) return HAL_ERROR_MASTERKEY_FAIL;
err =
masterkey_volatile_init() ||
hal_mkmif_write(core, MKM_VOLATILE_STATUS_ADDRESS + 4, buf, len) ||
- hal_mkmif_write_word(core, MKM_VOLATILE_STATUS_ADDRESS, HSM_MASTERKEY_SET);
-
- if (err != LIBHAL_OK) return HSM_MASTERKEY_FAIL;
+ hal_mkmif_write_word(core, MKM_VOLATILE_STATUS_ADDRESS, MKM_STATUS_SET);
- return HSM_MASTERKEY_OK;
+ return err;
}
-masterkey_status_t masterkey_volatile_erase(size_t len)
+hal_error_t masterkey_volatile_erase(size_t len)
{
uint8_t buf[KEK_LENGTH] = {0};
hal_error_t err;
- if (len != KEK_LENGTH) return HSM_MASTERKEY_FAIL;
+ if (len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH;
err =
masterkey_volatile_init() ||
hal_mkmif_write(core, MKM_VOLATILE_STATUS_ADDRESS + 4, buf, sizeof(buf)) ||
- hal_mkmif_write_word(core, MKM_VOLATILE_STATUS_ADDRESS, HSM_MASTERKEY_NOT_SET);
+ hal_mkmif_write_word(core, MKM_VOLATILE_STATUS_ADDRESS, MKM_STATUS_NOT_SET);
- if (err != LIBHAL_OK) return HSM_MASTERKEY_FAIL;
-
- return HSM_MASTERKEY_OK;
+ return err;
}
-/* Storing the master key in flash is a pretty Bad Idea, but since the Alpha board
- * doesn't have a battery mounted (only pin headers for attaching one), it might
- * help in non-production use where one doesn't have tamper protection anyways.
- *
- * For production use on the Alpha, one option is to have the Master Key on paper
- * and enter it into volatile RAM after each power on.
- */
hal_error_t masterkey_flash_init()
{
if (! flash_init) {
@@ -158,61 +183,70 @@ hal_error_t masterkey_flash_init()
return LIBHAL_OK;
}
-masterkey_status_t masterkey_flash_read(uint8_t *buf, size_t len)
+hal_error_t masterkey_flash_read(uint8_t *buf, size_t len)
{
uint8_t page[KEYSTORE_PAGE_SIZE];
uint32_t *status = (uint32_t *) page;
- if (len > sizeof(page) - 4) return HSM_MASTERKEY_FAIL;
+ if (len && len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH;
- if (masterkey_flash_init() != LIBHAL_OK) return HSM_MASTERKEY_FAIL;
+ if (masterkey_flash_init() != LIBHAL_OK) return HAL_ERROR_MASTERKEY_FAIL;
if (! keystore_read_data(MKM_FLASH_STATUS_ADDRESS, page, sizeof(page))) {
memset(page, 0, sizeof(page));
- return HSM_MASTERKEY_FAIL;
+ return HAL_ERROR_MASTERKEY_FAIL;
}
- if (buf != NULL && len) memcpy(buf, page + 4, len);
+ if (buf != NULL && len) {
+ /* Don't return what's in the flash memory in case it isn't initialized.
+ * Or maybe we should fill the buffer with proper random data in that case... hmm.
+ */
+ if (*status == MKM_STATUS_SET) {
+ memcpy(buf, page + 4, len);
+ } else {
+ memset(buf, 0x0, len);
+ }
+ }
memset(page + 4, 0, sizeof(page) - 4);
- if (*status == MKM_FLASH_STATUS_IN_USE) return HSM_MASTERKEY_SET;
- if (*status == 0x0 || *status == 0xffffffff) return HSM_MASTERKEY_NOT_SET;
+ if (*status == MKM_STATUS_SET) return LIBHAL_OK;
+ if (*status == MKM_STATUS_ERASED || *status == MKM_STATUS_NOT_SET) return HAL_ERROR_MASTERKEY_NOT_SET;
- return HSM_MASTERKEY_FAIL;
+ return HAL_ERROR_MASTERKEY_FAIL;
}
-masterkey_status_t masterkey_flash_write(uint8_t *buf, size_t len)
+hal_error_t masterkey_flash_write(uint8_t *buf, size_t len)
{
uint8_t page[KEYSTORE_PAGE_SIZE] = {0xff};
uint32_t *status = (uint32_t *) page;
int res;
- if (len > sizeof(page) - 4) return HSM_MASTERKEY_FAIL;
- if (buf == NULL) return HSM_MASTERKEY_FAIL;
+ if (len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH;
+ if (buf == NULL) return HAL_ERROR_MASTERKEY_FAIL;
- if (masterkey_flash_init() != LIBHAL_OK) return HSM_MASTERKEY_FAIL;
+ if (masterkey_flash_init() != LIBHAL_OK) return HAL_ERROR_MASTERKEY_FAIL;
- *status = MKM_FLASH_STATUS_IN_USE;
+ *status = MKM_STATUS_SET;
memcpy(page + 4, buf, len);
res = keystore_write_data(MKM_FLASH_STATUS_ADDRESS, page, sizeof(page));
memset(page, 0, sizeof(page));
if (res != 1) {
- return HSM_MASTERKEY_FAIL;
+ return HAL_ERROR_MASTERKEY_FAIL;
}
- return HSM_MASTERKEY_OK;
+ return LIBHAL_OK;
}
-masterkey_status_t masterkey_flash_erase(size_t len)
+hal_error_t masterkey_flash_erase(size_t len)
{
- if (len > KEYSTORE_PAGE_SIZE - 4) return HSM_MASTERKEY_FAIL;
+ if (len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH;
if (keystore_erase_sectors(MKM_FLASH_STATUS_ADDRESS / KEYSTORE_SECTOR_SIZE,
MKM_FLASH_STATUS_ADDRESS / KEYSTORE_SECTOR_SIZE) != 1) {
- return HSM_MASTERKEY_FAIL;
+ return HAL_ERROR_MASTERKEY_FAIL;
}
- return HSM_MASTERKEY_OK;
+ return LIBHAL_OK;
}
diff --git a/masterkey.h b/masterkey.h
index 8b47409..1d5e7a5 100644
--- a/masterkey.h
+++ b/masterkey.h
@@ -35,19 +35,12 @@
#ifndef __STM32_HSM_MASTERKEY_H
#define __STM32_HSM_MASTERKEY_H
-typedef enum {
- HSM_MASTERKEY_FAIL,
- HSM_MASTERKEY_OK,
- HSM_MASTERKEY_SET,
- HSM_MASTERKEY_NOT_SET,
-} masterkey_status_t;
+extern hal_error_t masterkey_volatile_read(uint8_t *buf, size_t len);
+extern hal_error_t masterkey_volatile_write(uint8_t *buf, size_t len);
+extern hal_error_t masterkey_volatile_erase(size_t len);
-extern masterkey_status_t masterkey_volatile_read(uint8_t *buf, size_t len);
-extern masterkey_status_t masterkey_volatile_write(uint8_t *buf, size_t len);
-extern masterkey_status_t masterkey_volatile_erase(size_t len);
-
-extern masterkey_status_t masterkey_flash_read(uint8_t *buf, size_t len);
-extern masterkey_status_t masterkey_flash_write(uint8_t *buf, size_t len);
-extern masterkey_status_t masterkey_flash_erase(size_t len);
+extern hal_error_t masterkey_flash_read(uint8_t *buf, size_t len);
+extern hal_error_t masterkey_flash_write(uint8_t *buf, size_t len);
+extern hal_error_t masterkey_flash_erase(size_t len);
#endif /* __STM32_HSM_MASTERKEY_H */
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