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OVMS3-idf/components/partition_table/gen_esp32part.py
Angus Gratton f8b191cfae secure boot: Pad to avoid data after the signature mapping into the address space 
Because address space is mapped in 64KB pages, it was possible for unauthenticated data after the
app .bin to become mapped into the flash cache address space.

This problem is solved by 2 changes:

* "esptool elf2image --secure-pad" will pad the image so that the signature block ends close to the
  64KB boundary. Due to alignment constraints it will be 12 bytes too short after signing (but
  with flash encryption, these 12 bytes are still encrypted as part of the last block and can't be
  arbitrarily changed).
* By default, secure boot now requires all app partitions to be a multiple of 64KB in size.
2018-07-23 13:45:55 +10:00

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18 KiB
Python
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#!/usr/bin/env python
#
# ESP32 partition table generation tool
#
# Converts partition tables to/from CSV and binary formats.
#
# See https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/partition-tables.html
# for explanation of partition table structure and uses.
#
# Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http:#www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import print_function, division
import argparse
import os
import re
import struct
import sys
import hashlib
import binascii
MAX_PARTITION_LENGTH = 0xC00 # 3K for partition data (96 entries) leaves 1K in a 4K sector for signature
MD5_PARTITION_BEGIN = b"\xEB\xEB" + b"\xFF" * 14 # The first 2 bytes are like magic numbers for MD5 sum
PARTITION_TABLE_SIZE = 0x1000 # Size of partition table
__version__ = '1.1'
quiet = False
md5sum = True
secure = False
offset_part_table = 0
def status(msg):
""" Print status message to stderr """
if not quiet:
critical(msg)
def critical(msg):
""" Print critical message to stderr """
if not quiet:
sys.stderr.write(msg)
sys.stderr.write('\n')
class PartitionTable(list):
def __init__(self):
super(PartitionTable, self).__init__(self)
@classmethod
def from_csv(cls, csv_contents):
res = PartitionTable()
lines = csv_contents.splitlines()
def expand_vars(f):
f = os.path.expandvars(f)
m = re.match(r'(?<!\\)\$([A-Za-z_][A-Za-z0-9_]*)', f)
if m:
raise InputError("unknown variable '%s'" % m.group(1))
return f
for line_no in range(len(lines)):
line = expand_vars(lines[line_no]).strip()
if line.startswith("#") or len(line) == 0:
continue
try:
res.append(PartitionDefinition.from_csv(line))
except InputError as e:
raise InputError("Error at line %d: %s" % (line_no+1, e))
except Exception:
critical("Unexpected error parsing line %d: %s" % (line_no+1, line))
raise
# fix up missing offsets & negative sizes
last_end = offset_part_table + PARTITION_TABLE_SIZE # first offset after partition table
for e in res:
if offset_part_table != 0 and e.offset is not None and e.offset < last_end:
critical("WARNING: 0x%x address in the partition table is below 0x%x" % (e.offset, last_end))
e.offset = None
if e.offset is None:
pad_to = 0x10000 if e.type == PartitionDefinition.APP_TYPE else 4
if last_end % pad_to != 0:
last_end += pad_to - (last_end % pad_to)
e.offset = last_end
if e.size < 0:
e.size = -e.size - e.offset
last_end = e.offset + e.size
return res
def __getitem__(self, item):
""" Allow partition table access via name as well as by
numeric index. """
if isinstance(item, str):
for x in self:
if x.name == item:
return x
raise ValueError("No partition entry named '%s'" % item)
else:
return super(PartitionTable, self).__getitem__(item)
def find_by_type(self, ptype, subtype):
""" Return a partition by type & subtype, returns
None if not found """
TYPES = PartitionDefinition.TYPES
SUBTYPES = PartitionDefinition.SUBTYPES
# convert ptype & subtypes names (if supplied this way) to integer values
try:
ptype = TYPES[ptype]
except KeyError:
try:
ptypes = int(ptype, 0)
except TypeError:
pass
try:
subtype = SUBTYPES[int(ptype)][subtype]
except KeyError:
try:
ptypes = int(ptype, 0)
except TypeError:
pass
for p in self:
if p.type == ptype and p.subtype == subtype:
return p
return None
def find_by_name(self, name):
for p in self:
if p.name == name:
return p
return None
def verify(self):
# verify each partition individually
for p in self:
p.verify()
# check for overlaps
last = None
for p in sorted(self, key=lambda x:x.offset):
if p.offset < offset_part_table + PARTITION_TABLE_SIZE:
raise InputError("Partition offset 0x%x is below 0x%x" % (p.offset, offset_part_table + PARTITION_TABLE_SIZE))
if last is not None and p.offset < last.offset + last.size:
raise InputError("Partition at 0x%x overlaps 0x%x-0x%x" % (p.offset, last.offset, last.offset+last.size-1))
last = p
def flash_size(self):
""" Return the size that partitions will occupy in flash
(ie the offset the last partition ends at)
"""
try:
last = sorted(self, reverse=True)[0]
except IndexError:
return 0 # empty table!
return last.offset + last.size
@classmethod
def from_binary(cls, b):
md5 = hashlib.md5();
result = cls()
for o in range(0,len(b),32):
data = b[o:o+32]
if len(data) != 32:
raise InputError("Partition table length must be a multiple of 32 bytes")
if data == b'\xFF'*32:
return result # got end marker
if md5sum and data[:2] == MD5_PARTITION_BEGIN[:2]: #check only the magic number part
if data[16:] == md5.digest():
continue # the next iteration will check for the end marker
else:
raise InputError("MD5 checksums don't match! (computed: 0x%s, parsed: 0x%s)" % (md5.hexdigest(), binascii.hexlify(data[16:])))
else:
md5.update(data)
result.append(PartitionDefinition.from_binary(data))
raise InputError("Partition table is missing an end-of-table marker")
def to_binary(self):
result = b"".join(e.to_binary() for e in self)
if md5sum:
result += MD5_PARTITION_BEGIN + hashlib.md5(result).digest()
if len(result )>= MAX_PARTITION_LENGTH:
raise InputError("Binary partition table length (%d) longer than max" % len(result))
result += b"\xFF" * (MAX_PARTITION_LENGTH - len(result)) # pad the sector, for signing
return result
def to_csv(self, simple_formatting=False):
rows = [ "# Espressif ESP32 Partition Table",
"# Name, Type, SubType, Offset, Size, Flags" ]
rows += [ x.to_csv(simple_formatting) for x in self ]
return "\n".join(rows) + "\n"
class PartitionDefinition(object):
APP_TYPE = 0x00
DATA_TYPE = 0x01
TYPES = {
"app" : APP_TYPE,
"data" : DATA_TYPE,
}
# Keep this map in sync with esp_partition_subtype_t enum in esp_partition.h
SUBTYPES = {
APP_TYPE : {
"factory" : 0x00,
"test" : 0x20,
},
DATA_TYPE : {
"ota" : 0x00,
"phy" : 0x01,
"nvs" : 0x02,
"coredump" : 0x03,
"esphttpd" : 0x80,
"fat" : 0x81,
"spiffs" : 0x82,
},
}
MAGIC_BYTES = b"\xAA\x50"
ALIGNMENT = {
APP_TYPE : 0x10000,
DATA_TYPE : 0x04,
}
# dictionary maps flag name (as used in CSV flags list, property name)
# to bit set in flags words in binary format
FLAGS = {
"encrypted" : 0
}
# add subtypes for the 16 OTA slot values ("ota_XX, etc.")
for ota_slot in range(16):
SUBTYPES[TYPES["app"]]["ota_%d" % ota_slot] = 0x10 + ota_slot
def __init__(self):
self.name = ""
self.type = None
self.subtype = None
self.offset = None
self.size = None
self.encrypted = False
@classmethod
def from_csv(cls, line):
""" Parse a line from the CSV """
line_w_defaults = line + ",,,," # lazy way to support default fields
fields = [ f.strip() for f in line_w_defaults.split(",") ]
res = PartitionDefinition()
res.name = fields[0]
res.type = res.parse_type(fields[1])
res.subtype = res.parse_subtype(fields[2])
res.offset = res.parse_address(fields[3])
res.size = res.parse_address(fields[4])
if res.size is None:
raise InputError("Size field can't be empty")
flags = fields[5].split(":")
for flag in flags:
if flag in cls.FLAGS:
setattr(res, flag, True)
elif len(flag) > 0:
raise InputError("CSV flag column contains unknown flag '%s'" % (flag))
return res
def __eq__(self, other):
return self.name == other.name and self.type == other.type \
and self.subtype == other.subtype and self.offset == other.offset \
and self.size == other.size
def __repr__(self):
def maybe_hex(x):
return "0x%x" % x if x is not None else "None"
return "PartitionDefinition('%s', 0x%x, 0x%x, %s, %s)" % (self.name, self.type, self.subtype or 0,
maybe_hex(self.offset), maybe_hex(self.size))
def __str__(self):
return "Part '%s' %d/%d @ 0x%x size 0x%x" % (self.name, self.type, self.subtype, self.offset or -1, self.size or -1)
def __cmp__(self, other):
return self.offset - other.offset
def __lt__(self, other):
return self.offset < other.offset
def __gt__(self, other):
return self.offset > other.offset
def __le__(self, other):
return self.offset <= other.offset
def __ge__(self, other):
return self.offset >= other.offset
def parse_type(self, strval):
if strval == "":
raise InputError("Field 'type' can't be left empty.")
return parse_int(strval, self.TYPES)
def parse_subtype(self, strval):
if strval == "":
return 0 # default
return parse_int(strval, self.SUBTYPES.get(self.type, {}))
def parse_address(self, strval):
if strval == "":
return None # PartitionTable will fill in default
return parse_int(strval)
def verify(self):
if self.type is None:
raise ValidationError(self, "Type field is not set")
if self.subtype is None:
raise ValidationError(self, "Subtype field is not set")
if self.offset is None:
raise ValidationError(self, "Offset field is not set")
align = self.ALIGNMENT.get(self.type, 4)
if self.offset % align:
raise ValidationError(self, "Offset 0x%x is not aligned to 0x%x" % (self.offset, align))
if self.size % align and secure:
raise ValidationError(self, "Size 0x%x is not aligned to 0x%x" % (self.size, align))
if self.size is None:
raise ValidationError(self, "Size field is not set")
STRUCT_FORMAT = "<2sBBLL16sL"
@classmethod
def from_binary(cls, b):
if len(b) != 32:
raise InputError("Partition definition length must be exactly 32 bytes. Got %d bytes." % len(b))
res = cls()
(magic, res.type, res.subtype, res.offset,
res.size, res.name, flags) = struct.unpack(cls.STRUCT_FORMAT, b)
if b"\x00" in res.name: # strip null byte padding from name string
res.name = res.name[:res.name.index(b"\x00")]
res.name = res.name.decode()
if magic != cls.MAGIC_BYTES:
raise InputError("Invalid magic bytes (%r) for partition definition" % magic)
for flag,bit in cls.FLAGS.items():
if flags & (1<<bit):
setattr(res, flag, True)
flags &= ~(1<<bit)
if flags != 0:
critical("WARNING: Partition definition had unknown flag(s) 0x%08x. Newer binary format?" % flags)
return res
def get_flags_list(self):
return [ flag for flag in self.FLAGS.keys() if getattr(self, flag) ]
def to_binary(self):
flags = sum((1 << self.FLAGS[flag]) for flag in self.get_flags_list())
return struct.pack(self.STRUCT_FORMAT,
self.MAGIC_BYTES,
self.type, self.subtype,
self.offset, self.size,
self.name.encode(),
flags)
def to_csv(self, simple_formatting=False):
def addr_format(a, include_sizes):
if not simple_formatting and include_sizes:
for (val, suffix) in [ (0x100000, "M"), (0x400, "K") ]:
if a % val == 0:
return "%d%s" % (a // val, suffix)
return "0x%x" % a
def lookup_keyword(t, keywords):
for k,v in keywords.items():
if simple_formatting == False and t == v:
return k
return "%d" % t
def generate_text_flags():
""" colon-delimited list of flags """
return ":".join(self.get_flags_list())
return ",".join([ self.name,
lookup_keyword(self.type, self.TYPES),
lookup_keyword(self.subtype, self.SUBTYPES.get(self.type, {})),
addr_format(self.offset, False),
addr_format(self.size, True),
generate_text_flags()])
def parse_int(v, keywords={}):
"""Generic parser for integer fields - int(x,0) with provision for
k/m/K/M suffixes and 'keyword' value lookup.
"""
try:
for letter, multiplier in [ ("k",1024), ("m",1024*1024) ]:
if v.lower().endswith(letter):
return parse_int(v[:-1], keywords) * multiplier
return int(v, 0)
except ValueError:
if len(keywords) == 0:
raise InputError("Invalid field value %s" % v)
try:
return keywords[v.lower()]
except KeyError:
raise InputError("Value '%s' is not valid. Known keywords: %s" % (v, ", ".join(keywords)))
def main():
global quiet
global md5sum
global offset_part_table
global secure
parser = argparse.ArgumentParser(description='ESP32 partition table utility')
parser.add_argument('--flash-size', help='Optional flash size limit, checks partition table fits in flash',
nargs='?', choices=[ '1MB', '2MB', '4MB', '8MB', '16MB' ])
parser.add_argument('--disable-md5sum', help='Disable md5 checksum for the partition table', default=False, action='store_true')
parser.add_argument('--verify', '-v', help='Verify partition table fields', default=True, action='store_false')
parser.add_argument('--quiet', '-q', help="Don't print status messages to stderr", action='store_true')
parser.add_argument('--offset', '-o', help='Set offset partition table', default='0x8000')
parser.add_argument('--secure', help="Require app partitions to be suitable for secure boot", action='store_true')
parser.add_argument('input', help='Path to CSV or binary file to parse. Will use stdin if omitted.', type=argparse.FileType('rb'), default=sys.stdin)
parser.add_argument('output', help='Path to output converted binary or CSV file. Will use stdout if omitted, unless the --display argument is also passed (in which case only the summary is printed.)',
nargs='?',
default='-')
args = parser.parse_args()
quiet = args.quiet
md5sum = not args.disable_md5sum
secure = args.secure
offset_part_table = int(args.offset, 0)
input = args.input.read()
input_is_binary = input[0:2] == PartitionDefinition.MAGIC_BYTES
if input_is_binary:
status("Parsing binary partition input...")
table = PartitionTable.from_binary(input)
else:
input = input.decode()
status("Parsing CSV input...")
table = PartitionTable.from_csv(input)
if args.verify:
status("Verifying table...")
table.verify()
if args.flash_size:
size_mb = int(args.flash_size.replace("MB", ""))
size = size_mb * 1024 * 1024 # flash memory uses honest megabytes!
table_size = table.flash_size()
if size < table_size:
raise InputError("Partitions defined in '%s' occupy %.1fMB of flash (%d bytes) which does not fit in configured flash size %dMB. Change the flash size in menuconfig under the 'Serial Flasher Config' menu." %
(args.input.name, table_size / 1024.0 / 1024.0, table_size, size_mb))
if input_is_binary:
output = table.to_csv()
with sys.stdout if args.output == '-' else open(args.output, 'w') as f:
f.write(output)
else:
output = table.to_binary()
with sys.stdout.buffer if args.output == '-' else open(args.output, 'wb') as f:
f.write(output)
class InputError(RuntimeError):
def __init__(self, e):
super(InputError, self).__init__(e)
class ValidationError(InputError):
def __init__(self, partition, message):
super(ValidationError, self).__init__(
"Partition %s invalid: %s" % (partition.name, message))
if __name__ == '__main__':
try:
main()
except InputError as e:
print(e, file=sys.stderr)
sys.exit(2)
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