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![Simon Glass](/assets/img/avatar_default.png)
This entry contains a Google Binary Block, used to store keys and bitmaps in a Chromium image. Signed-off-by: Simon Glass <sjg@chromium.org>
97 lines
3.3 KiB
Python
97 lines
3.3 KiB
Python
# SPDX-License-Identifier: GPL-2.0+
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# Copyright (c) 2018 Google, Inc
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# Written by Simon Glass <sjg@chromium.org>
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#
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# Support for a Chromium OS Google Binary Block, used to record read-only
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# information mostly used by firmware.
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from collections import OrderedDict
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import command
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from entry import Entry, EntryArg
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import fdt_util
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import tools
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# Build GBB flags.
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# (src/platform/vboot_reference/firmware/include/gbb_header.h)
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gbb_flag_properties = {
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'dev-screen-short-delay': 0x1,
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'load-option-roms': 0x2,
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'enable-alternate-os': 0x4,
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'force-dev-switch-on': 0x8,
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'force-dev-boot-usb': 0x10,
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'disable-fw-rollback-check': 0x20,
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'enter-triggers-tonorm': 0x40,
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'force-dev-boot-legacy': 0x80,
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'faft-key-override': 0x100,
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'disable-ec-software-sync': 0x200,
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'default-dev-boot-legacy': 0x400,
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'disable-pd-software-sync': 0x800,
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'disable-lid-shutdown': 0x1000,
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'force-dev-boot-fastboot-full-cap': 0x2000,
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'enable-serial': 0x4000,
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'disable-dwmp': 0x8000,
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}
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class Entry_gbb(Entry):
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"""An entry which contains a Chromium OS Google Binary Block
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Properties / Entry arguments:
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- hardware-id: Hardware ID to use for this build (a string)
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- keydir: Directory containing the public keys to use
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- bmpblk: Filename containing images used by recovery
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Chromium OS uses a GBB to store various pieces of information, in particular
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the root and recovery keys that are used to verify the boot process. Some
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more details are here:
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https://www.chromium.org/chromium-os/firmware-porting-guide/2-concepts
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but note that the page dates from 2013 so is quite out of date. See
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README.chromium for how to obtain the required keys and tools.
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"""
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def __init__(self, section, etype, node):
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Entry.__init__(self, section, etype, node)
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self.hardware_id, self.keydir, self.bmpblk = self.GetEntryArgsOrProps(
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[EntryArg('hardware-id', str),
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EntryArg('keydir', str),
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EntryArg('bmpblk', str)])
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# Read in the GBB flags from the config
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self.gbb_flags = 0
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flags_node = node.FindNode('flags')
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if flags_node:
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for flag, value in gbb_flag_properties.iteritems():
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if fdt_util.GetBool(flags_node, flag):
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self.gbb_flags |= value
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def ObtainContents(self):
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gbb = 'gbb.bin'
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fname = tools.GetOutputFilename(gbb)
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if not self.size:
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self.Raise('GBB must have a fixed size')
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gbb_size = self.size
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bmpfv_size = gbb_size - 0x2180
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if bmpfv_size < 0:
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self.Raise('GBB is too small (minimum 0x2180 bytes)')
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sizes = [0x100, 0x1000, bmpfv_size, 0x1000]
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sizes = ['%#x' % size for size in sizes]
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keydir = tools.GetInputFilename(self.keydir)
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gbb_set_command = [
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'gbb_utility', '-s',
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'--hwid=%s' % self.hardware_id,
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'--rootkey=%s/root_key.vbpubk' % keydir,
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'--recoverykey=%s/recovery_key.vbpubk' % keydir,
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'--flags=%d' % self.gbb_flags,
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'--bmpfv=%s' % tools.GetInputFilename(self.bmpblk),
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fname]
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tools.Run('futility', 'gbb_utility', '-c', ','.join(sizes), fname)
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tools.Run('futility', *gbb_set_command)
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self.SetContents(tools.ReadFile(fname))
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return True
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