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[ownership] Perform flash lockdown of owner flash regions
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1. Add the capability to perform lockdown of the MP region configuration
   via the REGION_CFG_REGWEN registers.
2. In `owner_block_flash_apply`, apply the PROTECT_WHEN_PRIMARY and LOCK
   properties only when lockdown is requested.
3. In the `{un,}locked_init` functions, do not perform lockdown:
   - We do not want regions locked for the `LockedOwner` state should
     the user request rescue mode.
   - We do not want regions locked in the ownership unlocked states.
4. Prior to execution handoff to owner code, engage the owner-configured
   locks.

Signed-off-by: Chris Frantz <[email protected]>
(cherry picked from commit de7df51)
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@cfrantz @moidx
cfrantz authored and moidx committed Oct 30, 2024
1 parent e6feb6a commit bb51827
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Showing 11 changed files with 116 additions and 50 deletions.
14 changes: 11 additions & 3 deletions sw/device/silicon_creator/lib/drivers/flash_ctrl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -587,7 +587,8 @@ static void flash_ctrl_mp_region_cfg_reset(flash_ctrl_region_index_t region) {
static void flash_ctrl_mp_region_cfg_write(flash_ctrl_region_index_t region,
flash_ctrl_cfg_t cfg,
flash_ctrl_perms_t perms,
multi_bit_bool_t en) {
multi_bit_bool_t en,
hardened_bool_t lock) {
#define FLASH_CTRL_MP_REGION_CFG_WRITE_(region_macro_arg) \
case ((region_macro_arg)): { \
HARDENED_CHECK_EQ(region, (region_macro_arg)); \
Expand Down Expand Up @@ -624,6 +625,12 @@ static void flash_ctrl_mp_region_cfg_write(flash_ctrl_region_index_t region,
sec_mmio_write32( \
kBase + FLASH_CTRL_MP_REGION_CFG_##region_macro_arg##_REG_OFFSET, \
mp_region_cfg); \
if (lock != kHardenedBoolFalse) { \
sec_mmio_write32( \
kBase + \
FLASH_CTRL_REGION_CFG_REGWEN_##region_macro_arg##_REG_OFFSET, \
0); \
} \
return; \
}

Expand All @@ -639,7 +646,8 @@ static void flash_ctrl_mp_region_cfg_write(flash_ctrl_region_index_t region,
void flash_ctrl_data_region_protect(flash_ctrl_region_index_t region,
uint32_t page_offset, uint32_t num_pages,
flash_ctrl_perms_t perms,
flash_ctrl_cfg_t cfg) {
flash_ctrl_cfg_t cfg,
hardened_bool_t lock) {
// Reset the region's configuration via the MP_REGION_CFG_${region} register.
// This temporarily disables memory protection for the region.
flash_ctrl_mp_region_cfg_reset(region);
Expand All @@ -649,7 +657,7 @@ void flash_ctrl_data_region_protect(flash_ctrl_region_index_t region,

// Write the new value of MP_REGION_CFG_${region}.
flash_ctrl_mp_region_cfg_write(region, cfg, perms,
/*en=*/kMultiBitBool4True);
/*en=*/kMultiBitBool4True, lock);
}

void flash_ctrl_info_cfg_set(const flash_ctrl_info_page_t *info_page,
Expand Down
3 changes: 2 additions & 1 deletion sw/device/silicon_creator/lib/drivers/flash_ctrl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -529,11 +529,12 @@ typedef uint32_t flash_ctrl_region_index_t;
* @param perms The read/write/erase permissions for this region.
* @param cfg Flash config values that are used to fill in some fields of the
* `MP_REGION_CFG_${region}` register.
* @param lock Lock the configuration for this region.
*/
void flash_ctrl_data_region_protect(flash_ctrl_region_index_t region,
uint32_t page_offset, uint32_t num_pages,
flash_ctrl_perms_t perms,
flash_ctrl_cfg_t cfg);
flash_ctrl_cfg_t cfg, hardened_bool_t lock);

/**
* Sets configuration settings for an info page.
Expand Down
3 changes: 2 additions & 1 deletion sw/device/silicon_creator/lib/drivers/flash_ctrl_unittest.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -968,7 +968,8 @@ TEST_P(DataRegionProtectTestSuite, ProtectRegionReadWriteEraseEnabled) {
.scrambling = BoolToMultiBitBool4(kFlashScrambling),
.ecc = BoolToMultiBitBool4(kFlashEcc),
.he = BoolToMultiBitBool4(kFlashHe),
});
},
kHardenedBoolFalse);
}

} // namespace
Expand Down
5 changes: 3 additions & 2 deletions sw/device/silicon_creator/lib/drivers/mock_flash_ctrl.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -81,9 +81,10 @@ void flash_ctrl_info_cfg_set(const flash_ctrl_info_page_t *info_page,
void flash_ctrl_data_region_protect(flash_ctrl_region_index_t region,
uint32_t page_offset, uint32_t num_pages,
flash_ctrl_perms_t perms,
flash_ctrl_cfg_t cfg) {
flash_ctrl_cfg_t cfg,
hardened_bool_t lock) {
MockFlashCtrl::Instance().DataRegionProtect(region, page_offset, num_pages,
perms, cfg);
perms, cfg, lock);
}

void flash_ctrl_bank_erase_perms_set(hardened_bool_t enable) {
Expand Down
2 changes: 1 addition & 1 deletion sw/device/silicon_creator/lib/drivers/mock_flash_ctrl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ class MockFlashCtrl : public global_mock::GlobalMock<MockFlashCtrl> {
MOCK_METHOD(void, DataRegionProtect,
(flash_ctrl_region_index_t region, uint32_t page_offset,
uint32_t num_pages, flash_ctrl_perms_t perms,
flash_ctrl_cfg_t cfg));
flash_ctrl_cfg_t cfg, hardened_bool_t));
MOCK_METHOD(void, InfoCfgSet,
(const flash_ctrl_info_page_t *, flash_ctrl_cfg_t));
MOCK_METHOD(void, BankErasePermsSet, (hardened_bool_t));
Expand Down
27 changes: 19 additions & 8 deletions sw/device/silicon_creator/lib/ownership/owner_block.c
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Original file line number Diff line number Diff line change
Expand Up @@ -85,10 +85,11 @@ rom_error_t owner_block_parse(const owner_block_t *block,
}

rom_error_t owner_block_flash_apply(const owner_flash_config_t *flash,
uint32_t config_side,
uint32_t primary_side) {
uint32_t config_side, uint32_t lockdown) {
if ((hardened_bool_t)flash == kHardenedBoolFalse)
return kErrorOk;
// TODO: Hardening: lockdown should be one of kBootSlotA, kBootSlotB or
// kHardenedBoolFalse.
uint32_t start = config_side == kBootSlotA ? 0
: config_side == kBootSlotB ? kFlashBankSize
: 0xFFFFFFFF;
Expand Down Expand Up @@ -118,13 +119,23 @@ rom_error_t owner_block_flash_apply(const owner_flash_config_t *flash,
.erase = bitfield_field32_read(val, FLASH_CONFIG_ERASE),
};

if (config_side == primary_side &&
bitfield_field32_read(val, FLASH_CONFIG_PROTECT_WHEN_PRIMARY) !=
kMultiBitBool4False) {
perm.write = kMultiBitBool4False;
perm.erase = kMultiBitBool4False;
if (lockdown == config_side) {
if (bitfield_field32_read(val, FLASH_CONFIG_PROTECT_WHEN_PRIMARY) !=
kMultiBitBool4False) {
perm.write = kMultiBitBool4False;
perm.erase = kMultiBitBool4False;
}
}

hardened_bool_t lock = kHardenedBoolFalse;
if (lockdown != kHardenedBoolFalse) {
if (bitfield_field32_read(val, FLASH_CONFIG_LOCK) !=
kMultiBitBool4False) {
lock = kHardenedBoolTrue;
}
}
flash_ctrl_data_region_protect(i, config->start, config->size, perm, cfg);
flash_ctrl_data_region_protect(i, config->start, config->size, perm, cfg,
lock);
}
}
return kErrorOk;
Expand Down
7 changes: 4 additions & 3 deletions sw/device/silicon_creator/lib/ownership/owner_block.h
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Original file line number Diff line number Diff line change
Expand Up @@ -67,12 +67,13 @@ rom_error_t owner_block_parse(const owner_block_t *block,
*
* @param flash A pointer to a flash configuration struct.
* @param config_side Which side of the flash to configure.
* @param primary_side Which side of the flash is primary.
* @param lockdown Apply any special lockdown configuration to the specified
* side of the flash. May use kHardenedBoolFalse to skip
* lockdown.
* @return error code.
*/
rom_error_t owner_block_flash_apply(const owner_flash_config_t *flash,
uint32_t config_side,
uint32_t primary_side);
uint32_t config_side, uint32_t lockdown);

/**
* Apply the flash info configuration parameters from the owner block.
Expand Down
51 changes: 30 additions & 21 deletions sw/device/silicon_creator/lib/ownership/owner_block_unittest.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -239,21 +239,24 @@ TEST_F(OwnerBlockTest, FlashConfigApplySideA) {
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4False, kMultiBitBool4False,
kMultiBitBool4False)));
kMultiBitBool4False),
kHardenedBoolFalse));
EXPECT_CALL(
flash_ctrl_,
DataRegionProtect(1, 32, 192,
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4False)));
DataRegionProtect(
1, 32, 192,
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4True, kMultiBitBool4True, kMultiBitBool4False),
kHardenedBoolFalse));
EXPECT_CALL(
flash_ctrl_,
DataRegionProtect(2, 224, 32,
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4False, kMultiBitBool4False,
kMultiBitBool4True)));
kMultiBitBool4True),
kHardenedBoolFalse));

rom_error_t error =
owner_block_flash_apply(&simple_flash_config, kBootSlotA, 0);
Expand All @@ -270,21 +273,24 @@ TEST_F(OwnerBlockTest, FlashConfigApplySideAPrimary) {
FlashPerms(kMultiBitBool4True, kMultiBitBool4False,
kMultiBitBool4False),
FlashCfg(kMultiBitBool4False, kMultiBitBool4False,
kMultiBitBool4False)));
kMultiBitBool4False),
kHardenedBoolFalse));
EXPECT_CALL(
flash_ctrl_,
DataRegionProtect(1, 32, 192,
FlashPerms(kMultiBitBool4True, kMultiBitBool4False,
kMultiBitBool4False),
FlashCfg(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4False)));
DataRegionProtect(
1, 32, 192,
FlashPerms(kMultiBitBool4True, kMultiBitBool4False,
kMultiBitBool4False),
FlashCfg(kMultiBitBool4True, kMultiBitBool4True, kMultiBitBool4False),
kHardenedBoolFalse));
EXPECT_CALL(
flash_ctrl_,
DataRegionProtect(2, 224, 32,
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4False, kMultiBitBool4False,
kMultiBitBool4True)));
kMultiBitBool4True),
kHardenedBoolFalse));

rom_error_t error =
owner_block_flash_apply(&simple_flash_config, kBootSlotA, kBootSlotA);
Expand All @@ -299,21 +305,24 @@ TEST_F(OwnerBlockTest, FlashConfigApplySideB) {
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4False, kMultiBitBool4False,
kMultiBitBool4False)));
kMultiBitBool4False),
kHardenedBoolFalse));
EXPECT_CALL(
flash_ctrl_,
DataRegionProtect(4, 256 + 32, 192,
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4False)));
DataRegionProtect(
4, 256 + 32, 192,
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4True, kMultiBitBool4True, kMultiBitBool4False),
kHardenedBoolFalse));
EXPECT_CALL(
flash_ctrl_,
DataRegionProtect(5, 256 + 224, 32,
FlashPerms(kMultiBitBool4True, kMultiBitBool4True,
kMultiBitBool4True),
FlashCfg(kMultiBitBool4False, kMultiBitBool4False,
kMultiBitBool4True)));
kMultiBitBool4True),
kHardenedBoolFalse));

rom_error_t error =
owner_block_flash_apply(&simple_flash_config, kBootSlotB, 0);
Expand Down
35 changes: 27 additions & 8 deletions sw/device/silicon_creator/lib/ownership/ownership.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -87,10 +87,12 @@ static rom_error_t locked_owner_init(boot_data_t *bootdata,
return kErrorOwnershipBadInfoPage;
}
HARDENED_RETURN_IF_ERROR(owner_block_parse(&owner_page[0], config, keyring));
HARDENED_RETURN_IF_ERROR(owner_block_flash_apply(config->flash, kBootSlotA,
bootdata->primary_bl0_slot));
HARDENED_RETURN_IF_ERROR(owner_block_flash_apply(config->flash, kBootSlotB,
bootdata->primary_bl0_slot));
HARDENED_RETURN_IF_ERROR(
owner_block_flash_apply(config->flash, kBootSlotA,
/*lockdown=*/kHardenedBoolFalse));
HARDENED_RETURN_IF_ERROR(
owner_block_flash_apply(config->flash, kBootSlotB,
/*lockdown=*/kHardenedBoolFalse));
HARDENED_RETURN_IF_ERROR(owner_block_info_apply(config->info));
return kErrorOk;
}
Expand Down Expand Up @@ -150,8 +152,9 @@ static rom_error_t unlocked_init(boot_data_t *bootdata, owner_config_t *config,
// Configure the primary half of the flash as Owner Page 0 requests.
HARDENED_RETURN_IF_ERROR(
owner_block_parse(&owner_page[0], config, keyring));
HARDENED_RETURN_IF_ERROR(owner_block_flash_apply(
config->flash, bootdata->primary_bl0_slot, bootdata->primary_bl0_slot));
HARDENED_RETURN_IF_ERROR(
owner_block_flash_apply(config->flash, bootdata->primary_bl0_slot,
/*lockdown=*/kHardenedBoolFalse));
}

if (ownership_page1_valid_for_transfer(bootdata) == kHardenedBoolTrue) {
Expand All @@ -160,8 +163,9 @@ static rom_error_t unlocked_init(boot_data_t *bootdata, owner_config_t *config,
HARDENED_RETURN_IF_ERROR(
owner_block_parse(&owner_page[1], config, keyring));
}
HARDENED_RETURN_IF_ERROR(owner_block_flash_apply(config->flash, secondary,
bootdata->primary_bl0_slot));
HARDENED_RETURN_IF_ERROR(
owner_block_flash_apply(config->flash, secondary,
/*lockdown=*/kHardenedBoolFalse));
HARDENED_RETURN_IF_ERROR(owner_block_info_apply(config->info));
return kErrorOk;
}
Expand Down Expand Up @@ -244,6 +248,21 @@ rom_error_t ownership_init(boot_data_t *bootdata, owner_config_t *config,
return error;
}

rom_error_t ownership_flash_lockdown(boot_data_t *bootdata,
const owner_config_t *config) {
if (bootdata->ownership_state == kOwnershipStateLockedOwner) {
HARDENED_RETURN_IF_ERROR(
owner_block_flash_apply(config->flash, kBootSlotA,
/*lockdown=*/bootdata->primary_bl0_slot));
HARDENED_RETURN_IF_ERROR(
owner_block_flash_apply(config->flash, kBootSlotB,
/*lockdown=*/bootdata->primary_bl0_slot));
} else {
HARDENED_CHECK_NE(bootdata->ownership_state, kOwnershipStateLockedOwner);
}
return kErrorOk;
}

void ownership_page_seal(size_t page) {
size_t seal_len = (uintptr_t)&owner_page[0].seal - (uintptr_t)&owner_page[0];
hmac_digest_t digest;
Expand Down
11 changes: 11 additions & 0 deletions sw/device/silicon_creator/lib/ownership/ownership.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,17 @@ rom_error_t ownership_init(boot_data_t *bootdata, owner_config_t *config,
*/
hardened_bool_t ownership_page1_valid_for_transfer(boot_data_t *bootdata);

/**
* Lockdown the flash configuration.
*
*
* @param bootdata The current bootdata.
* @param config The current owner configuration.
* @return error state.
*/
rom_error_t ownership_flash_lockdown(boot_data_t *bootdata,
const owner_config_t *config);

/**
* Seal an owner page.
*
Expand Down
8 changes: 6 additions & 2 deletions sw/device/silicon_creator/rom_ext/rom_ext.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -495,7 +495,8 @@ static rom_error_t rom_ext_attestation_owner(const manifest_t *owner_manifest) {
}

OT_WARN_UNUSED_RESULT
static rom_error_t rom_ext_boot(const manifest_t *manifest) {
static rom_error_t rom_ext_boot(boot_data_t *boot_data,
const manifest_t *manifest) {
// Generate CDI_1 attestation keys and certificate.
HARDENED_RETURN_IF_ERROR(rom_ext_attestation_owner(manifest));

Expand Down Expand Up @@ -637,6 +638,9 @@ static rom_error_t rom_ext_boot(const manifest_t *manifest) {
ibex_addr_remap_lockdown(0);
ibex_addr_remap_lockdown(1);

// Lock the flash according to the ownership configuration.
HARDENED_RETURN_IF_ERROR(ownership_flash_lockdown(boot_data, &owner_config));

dbg_print_epmp();

// Verify expectations before jumping to owner code.
Expand Down Expand Up @@ -819,7 +823,7 @@ static rom_error_t rom_ext_try_next_stage(boot_data_t *boot_data,
boot_log_digest_update(boot_log);

// Boot fails if a verified ROM_EXT cannot be booted.
RETURN_IF_ERROR(rom_ext_boot(manifests.ordered[i]));
RETURN_IF_ERROR(rom_ext_boot(boot_data, manifests.ordered[i]));
// `rom_ext_boot()` should never return `kErrorOk`, but if it does
// we must shut down the chip instead of trying the next ROM_EXT.
return kErrorRomExtBootFailed;
Expand Down

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