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Commit f99b5314 authored by Sami Tolvanen's avatar Sami Tolvanen
Browse files

Error correction: Append codes to verified partitions 

Append error-correcting codes to verified partitions provided that
PRODUCT_SUPPORTS_VERITY_FEC is true.

This moves verity metadata to be after the hash tree, and requires
matching changes from
  Ide48f581bbba77aed6132f77b309db71630d81ed

Bug: 21893453
Change-Id: I6945cbab99e214566a1f9d3702333f2dbbc35816
parent 58fbd697

core/Makefile

+6 −1
Original line number Diff line number Diff line
@@ -724,6 +724,9 @@ INTERNAL_USERIMAGES_BINARY_PATHS := $(sort $(dir $(INTERNAL_USERIMAGES_DEPS))) 


ifeq (true,$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY))

INTERNAL_USERIMAGES_DEPS += $(BUILD_VERITY_TREE) $(APPEND2SIMG) $(VERITY_SIGNER)

ifeq (true,$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY_FEC))

INTERNAL_USERIMAGES_DEPS += $(FEC)

endif

endif



SELINUX_FC := $(TARGET_ROOT_OUT)/file_contexts.bin
@@ -754,6 +757,7 @@ $(if $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_BOOT_SIGNER),$(hide) echo " 
$(if $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY),$(hide) echo "verity=$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY)" >> $(1))

$(if $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY),$(hide) echo "verity_key=$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_VERITY_SIGNING_KEY)" >> $(1))

$(if $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY),$(hide) echo "verity_signer_cmd=$(notdir $(VERITY_SIGNER))" >> $(1))

$(if $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY_FEC),$(hide) echo "verity_fec=$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY_FEC)" >> $(1))

$(if $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SYSTEM_VERITY_PARTITION),$(hide) echo "system_verity_block_device=$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SYSTEM_VERITY_PARTITION)" >> $(1))

$(if $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_VENDOR_VERITY_PARTITION),$(hide) echo "vendor_verity_block_device=$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_VENDOR_VERITY_PARTITION)" >> $(1))

$(if $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VBOOT),$(hide) echo "vboot=$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VBOOT)" >> $(1))
@@ -1363,7 +1367,8 @@ OTATOOLS := $(HOST_OUT_EXECUTABLES)/minigzip \ 
  $(HOST_OUT_EXECUTABLES)/verity_signer \

  $(HOST_OUT_EXECUTABLES)/append2simg \

  $(HOST_OUT_EXECUTABLES)/img2simg \

  $(HOST_OUT_EXECUTABLES)/boot_signer

  $(HOST_OUT_EXECUTABLES)/boot_signer \

  $(HOST_OUT_EXECUTABLES)/fec



# Shared libraries.

OTATOOLS += \

core/config.mk

+1 −0
Original line number Diff line number Diff line
@@ -515,6 +515,7 @@ BUILD_VERITY_TREE := $(HOST_OUT_EXECUTABLES)/build_verity_tree 
BOOT_SIGNER := $(HOST_OUT_EXECUTABLES)/boot_signer

FUTILITY := prebuilts/misc/$(BUILD_OS)-$(HOST_PREBUILT_ARCH)/futility/futility

VBOOT_SIGNER := prebuilts/misc/scripts/vboot_signer/vboot_signer.sh

FEC := $(HOST_OUT_EXECUTABLES)/fec



# ACP is always for the build OS, not for the host OS

ACP := $(BUILD_OUT_EXECUTABLES)/acp$(BUILD_EXECUTABLE_SUFFIX)

core/product.mk

+1 −0
Original line number Diff line number Diff line
@@ -100,6 +100,7 @@ _product_var_list := \ 
    PRODUCT_SUPPORTS_BOOT_SIGNER \

    PRODUCT_SUPPORTS_VBOOT \

    PRODUCT_SUPPORTS_VERITY \

    PRODUCT_SUPPORTS_VERITY_FEC \

    PRODUCT_OEM_PROPERTIES \

    PRODUCT_SYSTEM_PROPERTY_BLACKLIST \

    PRODUCT_SYSTEM_SERVER_JARS \

target/product/verity.mk

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ user_variant := $(filter user userdebug,$(TARGET_BUILD_VARIANT)) 
ifneq (,$(user_variant))

    PRODUCT_SUPPORTS_BOOT_SIGNER := true

    PRODUCT_SUPPORTS_VERITY := true

    PRODUCT_SUPPORTS_VERITY_FEC := true



    # The dev key is used to sign boot and recovery images, and the verity

    # metadata table. Actual product deliverables will be re-signed by hand.

tools/releasetools/build_image.py

+85 −17
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ import tempfile 
OPTIONS = common.OPTIONS



FIXED_SALT = "aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7"

BLOCK_SIZE = 4096



def RunCommand(cmd):

  """Echo and run the given command.
@@ -48,6 +49,14 @@ def RunCommand(cmd): 
  print "%s" % (output.rstrip(),)

  return (output, p.returncode)



def GetVerityFECSize(partition_size):

  cmd = "fec -s %d" % partition_size

  status, output = commands.getstatusoutput(cmd)

  if status:

    print output

    return False, 0

  return True, int(output)



def GetVerityTreeSize(partition_size):

  cmd = "build_verity_tree -s %d"

  cmd %= partition_size
@@ -67,7 +76,22 @@ def GetVerityMetadataSize(partition_size): 
    return False, 0

  return True, int(output)



def AdjustPartitionSizeForVerity(partition_size):

def GetVeritySize(partition_size, fec_supported):

  success, verity_tree_size = GetVerityTreeSize(partition_size)

  if not success:

    return 0

  success, verity_metadata_size = GetVerityMetadataSize(partition_size)

  if not success:

    return 0

  verity_size = verity_tree_size + verity_metadata_size

  if fec_supported:

    success, fec_size = GetVerityFECSize(partition_size + verity_size)

    if not success:

      return 0

    return verity_size + fec_size

  return verity_size



def AdjustPartitionSizeForVerity(partition_size, fec_supported):

  """Modifies the provided partition size to account for the verity metadata.



  This information is used to size the created image appropriately.
@@ -76,13 +100,43 @@ def AdjustPartitionSizeForVerity(partition_size): 
  Returns:

    The size of the partition adjusted for verity metadata.

  """

  success, verity_tree_size = GetVerityTreeSize(partition_size)

  if not success:

    return 0

  success, verity_metadata_size = GetVerityMetadataSize(partition_size)

  if not success:

    return 0

  return partition_size - verity_tree_size - verity_metadata_size

  key = "%d %d" % (partition_size, fec_supported)

  if key in AdjustPartitionSizeForVerity.results:

    return AdjustPartitionSizeForVerity.results[key]



  hi = partition_size

  if hi % BLOCK_SIZE != 0:

    hi = (hi // BLOCK_SIZE) * BLOCK_SIZE



  # verity tree and fec sizes depend on the partition size, which

  # means this estimate is always going to be unnecessarily small

  lo = partition_size - GetVeritySize(hi, fec_supported)

  result = lo



  # do a binary search for the optimal size

  while lo < hi:

    i = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE

    size = i + GetVeritySize(i, fec_supported)

    if size <= partition_size:

      if result < i:

        result = i

      lo = i + BLOCK_SIZE

    else:

      hi = i



  AdjustPartitionSizeForVerity.results[key] = result

  return result



AdjustPartitionSizeForVerity.results = {}



def BuildVerityFEC(sparse_image_path, verity_fec_path, prop_dict):

  cmd = "fec -e %s %s" % (sparse_image_path, verity_fec_path)

  print cmd

  status, output = commands.getstatusoutput(cmd)

  if status:

    print "Could not build FEC data! Error: %s" % output

    return False

  return True



def BuildVerityTree(sparse_image_path, verity_image_path, prop_dict):

  cmd = "build_verity_tree -A %s %s %s" % (
@@ -130,12 +184,12 @@ def Append2Simg(sparse_image_path, unsparse_image_path, error_message): 


def BuildVerifiedImage(data_image_path, verity_image_path,

                       verity_metadata_path):

  if not Append2Simg(data_image_path, verity_metadata_path,

                     "Could not append verity metadata!"):

    return False

  if not Append2Simg(data_image_path, verity_image_path,

                     "Could not append verity tree!"):

    return False

  if not Append2Simg(data_image_path, verity_metadata_path,

                     "Could not append verity metadata!"):

    return False

  return True



def UnsparseImage(sparse_image_path, replace=True):
@@ -154,7 +208,7 @@ def UnsparseImage(sparse_image_path, replace=True): 
    return False, None

  return True, unsparse_image_path



def MakeVerityEnabledImage(out_file, prop_dict):

def MakeVerityEnabledImage(out_file, fec_supported, prop_dict):

  """Creates an image that is verifiable using dm-verity.



  Args:
@@ -180,6 +234,7 @@ def MakeVerityEnabledImage(out_file, prop_dict): 
  # get partial image paths

  verity_image_path = os.path.join(tempdir_name, "verity.img")

  verity_metadata_path = os.path.join(tempdir_name, "verity_metadata.img")

  verity_fec_path = os.path.join(tempdir_name, "verity_fec.img")



  # build the verity tree and get the root hash and salt

  if not BuildVerityTree(out_file, verity_image_path, prop_dict):
@@ -201,6 +256,16 @@ def MakeVerityEnabledImage(out_file, prop_dict): 
    shutil.rmtree(tempdir_name, ignore_errors=True)

    return False



  if fec_supported:

    # build FEC for the entire partition, including metadata

    if not BuildVerityFEC(out_file, verity_fec_path, prop_dict):

      shutil.rmtree(tempdir_name, ignore_errors=True)

      return False



    if not Append2Simg(out_file, verity_fec_path, "Could not append FEC!"):

      shutil.rmtree(tempdir_name, ignore_errors=True)

      return False



  shutil.rmtree(tempdir_name, ignore_errors=True)

  return True
@@ -248,12 +313,14 @@ def BuildImage(in_dir, prop_dict, out_file, target_out=None): 


  is_verity_partition = "verity_block_device" in prop_dict

  verity_supported = prop_dict.get("verity") == "true"

  verity_fec_supported = prop_dict.get("verity_fec") == "true"



  # Adjust the partition size to make room for the hashes if this is to be

  # verified.

  if verity_supported and is_verity_partition and fs_spans_partition:

    partition_size = int(prop_dict.get("partition_size"))



    adjusted_size = AdjustPartitionSizeForVerity(partition_size)

    adjusted_size = AdjustPartitionSizeForVerity(partition_size,

                                                 verity_fec_supported)

    if not adjusted_size:

      return False

    prop_dict["partition_size"] = str(adjusted_size)
@@ -366,7 +433,7 @@ def BuildImage(in_dir, prop_dict, out_file, target_out=None): 
            "%d" % (mount_point, image_size, partition_size))

      return False

    if verity_supported and is_verity_partition:

      if 2 * image_size - AdjustPartitionSizeForVerity(image_size) > partition_size:

      if 2 * image_size - AdjustPartitionSizeForVerity(image_size, verity_fec_supported) > partition_size:

        print "Error: No more room on %s to fit verity data" % mount_point

        return False

    prop_dict["original_partition_size"] = prop_dict["partition_size"]
@@ -374,7 +441,7 @@ def BuildImage(in_dir, prop_dict, out_file, target_out=None): 


  # create the verified image if this is to be verified

  if verity_supported and is_verity_partition:

    if not MakeVerityEnabledImage(out_file, prop_dict):

    if not MakeVerityEnabledImage(out_file, verity_fec_supported, prop_dict):

      return False



  if run_fsck and prop_dict.get("skip_fsck") != "true":
@@ -416,7 +483,8 @@ def ImagePropFromGlobalDict(glob_dict, mount_point): 
      "skip_fsck",

      "verity",

      "verity_key",

      "verity_signer_cmd"

      "verity_signer_cmd",

      "verity_fec"

      )

  for p in common_props:

    copy_prop(p, p)