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u-boot/test/py/tests/test_fit.py
Simon Glass 79af75f777 fit: Don't allow verification of images with @ nodes 
When searching for a node called 'fred', any unit address appended to the
name is ignored by libfdt, meaning that 'fred' can match 'fred@1'. This
means that we cannot be sure that the node originally intended is the one
that is used.

Disallow use of nodes with unit addresses.

Update the forge test also, since it uses @ addresses.

CVE-2021-27138

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Bruce Monroe <bruce.monroe@intel.com>
Reported-by: Arie Haenel <arie.haenel@intel.com>
Reported-by: Julien Lenoir <julien.lenoir@intel.com>
2021-02-15 19:17:25 -05:00

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# SPDX-License-Identifier: GPL-2.0+
# Copyright (c) 2013, Google Inc.
#
# Sanity check of the FIT handling in U-Boot
import os
import pytest
import struct
import u_boot_utils as util
# Define a base ITS which we can adjust using % and a dictionary
base_its = '''
/dts-v1/;
/ {
description = "Chrome OS kernel image with one or more FDT blobs";
#address-cells = <1>;
images {
kernel-1 {
data = /incbin/("%(kernel)s");
type = "kernel";
arch = "sandbox";
os = "linux";
compression = "%(compression)s";
load = <0x40000>;
entry = <0x8>;
};
kernel-2 {
data = /incbin/("%(loadables1)s");
type = "kernel";
arch = "sandbox";
os = "linux";
compression = "none";
%(loadables1_load)s
entry = <0x0>;
};
fdt-1 {
description = "snow";
data = /incbin/("%(fdt)s");
type = "flat_dt";
arch = "sandbox";
%(fdt_load)s
compression = "%(compression)s";
signature-1 {
algo = "sha1,rsa2048";
key-name-hint = "dev";
};
};
ramdisk-1 {
description = "snow";
data = /incbin/("%(ramdisk)s");
type = "ramdisk";
arch = "sandbox";
os = "linux";
%(ramdisk_load)s
compression = "%(compression)s";
};
ramdisk-2 {
description = "snow";
data = /incbin/("%(loadables2)s");
type = "ramdisk";
arch = "sandbox";
os = "linux";
%(loadables2_load)s
compression = "none";
};
};
configurations {
default = "conf-1";
conf-1 {
kernel = "kernel-1";
fdt = "fdt-1";
%(ramdisk_config)s
%(loadables_config)s
};
};
};
'''
# Define a base FDT - currently we don't use anything in this
base_fdt = '''
/dts-v1/;
/ {
#address-cells = <1>;
#size-cells = <0>;
model = "Sandbox Verified Boot Test";
compatible = "sandbox";
reset@0 {
compatible = "sandbox,reset";
reg = <0>;
};
};
'''
# This is the U-Boot script that is run for each test. First load the FIT,
# then run the 'bootm' command, then save out memory from the places where
# we expect 'bootm' to write things. Then quit.
base_script = '''
host load hostfs 0 %(fit_addr)x %(fit)s
fdt addr %(fit_addr)x
bootm start %(fit_addr)x
bootm loados
host save hostfs 0 %(kernel_addr)x %(kernel_out)s %(kernel_size)x
host save hostfs 0 %(fdt_addr)x %(fdt_out)s %(fdt_size)x
host save hostfs 0 %(ramdisk_addr)x %(ramdisk_out)s %(ramdisk_size)x
host save hostfs 0 %(loadables1_addr)x %(loadables1_out)s %(loadables1_size)x
host save hostfs 0 %(loadables2_addr)x %(loadables2_out)s %(loadables2_size)x
'''
@pytest.mark.boardspec('sandbox')
@pytest.mark.buildconfigspec('fit_signature')
@pytest.mark.requiredtool('dtc')
def test_fit(u_boot_console):
def make_fname(leaf):
"""Make a temporary filename
Args:
leaf: Leaf name of file to create (within temporary directory)
Return:
Temporary filename
"""
return os.path.join(cons.config.build_dir, leaf)
def filesize(fname):
"""Get the size of a file
Args:
fname: Filename to check
Return:
Size of file in bytes
"""
return os.stat(fname).st_size
def read_file(fname):
"""Read the contents of a file
Args:
fname: Filename to read
Returns:
Contents of file as a string
"""
with open(fname, 'rb') as fd:
return fd.read()
def make_dtb():
"""Make a sample .dts file and compile it to a .dtb
Returns:
Filename of .dtb file created
"""
src = make_fname('u-boot.dts')
dtb = make_fname('u-boot.dtb')
with open(src, 'w') as fd:
fd.write(base_fdt)
util.run_and_log(cons, ['dtc', src, '-O', 'dtb', '-o', dtb])
return dtb
def make_its(params):
"""Make a sample .its file with parameters embedded
Args:
params: Dictionary containing parameters to embed in the %() strings
Returns:
Filename of .its file created
"""
its = make_fname('test.its')
with open(its, 'w') as fd:
print(base_its % params, file=fd)
return its
def make_fit(mkimage, params):
"""Make a sample .fit file ready for loading
This creates a .its script with the selected parameters and uses mkimage to
turn this into a .fit image.
Args:
mkimage: Filename of 'mkimage' utility
params: Dictionary containing parameters to embed in the %() strings
Return:
Filename of .fit file created
"""
fit = make_fname('test.fit')
its = make_its(params)
util.run_and_log(cons, [mkimage, '-f', its, fit])
with open(make_fname('u-boot.dts'), 'w') as fd:
fd.write(base_fdt)
return fit
def make_kernel(filename, text):
"""Make a sample kernel with test data
Args:
filename: the name of the file you want to create
Returns:
Full path and filename of the kernel it created
"""
fname = make_fname(filename)
data = ''
for i in range(100):
data += 'this %s %d is unlikely to boot\n' % (text, i)
with open(fname, 'w') as fd:
print(data, file=fd)
return fname
def make_ramdisk(filename, text):
"""Make a sample ramdisk with test data
Returns:
Filename of ramdisk created
"""
fname = make_fname(filename)
data = ''
for i in range(100):
data += '%s %d was seldom used in the middle ages\n' % (text, i)
with open(fname, 'w') as fd:
print(data, file=fd)
return fname
def make_compressed(filename):
util.run_and_log(cons, ['gzip', '-f', '-k', filename])
return filename + '.gz'
def find_matching(text, match):
"""Find a match in a line of text, and return the unmatched line portion
This is used to extract a part of a line from some text. The match string
is used to locate the line - we use the first line that contains that
match text.
Once we find a match, we discard the match string itself from the line,
and return what remains.
TODO: If this function becomes more generally useful, we could change it
to use regex and return groups.
Args:
text: Text to check (list of strings, one for each command issued)
match: String to search for
Return:
String containing unmatched portion of line
Exceptions:
ValueError: If match is not found
>>> find_matching(['first line:10', 'second_line:20'], 'first line:')
'10'
>>> find_matching(['first line:10', 'second_line:20'], 'second line')
Traceback (most recent call last):
...
ValueError: Test aborted
>>> find_matching('first line:10\', 'second_line:20'], 'second_line:')
'20'
>>> find_matching('first line:10\', 'second_line:20\nthird_line:30'],
'third_line:')
'30'
"""
__tracebackhide__ = True
for line in '\n'.join(text).splitlines():
pos = line.find(match)
if pos != -1:
return line[:pos] + line[pos + len(match):]
pytest.fail("Expected '%s' but not found in output")
def check_equal(expected_fname, actual_fname, failure_msg):
"""Check that a file matches its expected contents
This is always used on out-buffers whose size is decided by the test
script anyway, which in some cases may be larger than what we're
actually looking for. So it's safe to truncate it to the size of the
expected data.
Args:
expected_fname: Filename containing expected contents
actual_fname: Filename containing actual contents
failure_msg: Message to print on failure
"""
expected_data = read_file(expected_fname)
actual_data = read_file(actual_fname)
if len(expected_data) < len(actual_data):
actual_data = actual_data[:len(expected_data)]
assert expected_data == actual_data, failure_msg
def check_not_equal(expected_fname, actual_fname, failure_msg):
"""Check that a file does not match its expected contents
Args:
expected_fname: Filename containing expected contents
actual_fname: Filename containing actual contents
failure_msg: Message to print on failure
"""
expected_data = read_file(expected_fname)
actual_data = read_file(actual_fname)
assert expected_data != actual_data, failure_msg
def run_fit_test(mkimage):
"""Basic sanity check of FIT loading in U-Boot
TODO: Almost everything:
- hash algorithms - invalid hash/contents should be detected
- signature algorithms - invalid sig/contents should be detected
- compression
- checking that errors are detected like:
- image overwriting
- missing images
- invalid configurations
- incorrect os/arch/type fields
- empty data
- images too large/small
- invalid FDT (e.g. putting a random binary in instead)
- default configuration selection
- bootm command line parameters should have desired effect
- run code coverage to make sure we are testing all the code
"""
# Set up invariant files
control_dtb = make_dtb()
kernel = make_kernel('test-kernel.bin', 'kernel')
ramdisk = make_ramdisk('test-ramdisk.bin', 'ramdisk')
loadables1 = make_kernel('test-loadables1.bin', 'lenrek')
loadables2 = make_ramdisk('test-loadables2.bin', 'ksidmar')
kernel_out = make_fname('kernel-out.bin')
fdt = make_fname('u-boot.dtb')
fdt_out = make_fname('fdt-out.dtb')
ramdisk_out = make_fname('ramdisk-out.bin')
loadables1_out = make_fname('loadables1-out.bin')
loadables2_out = make_fname('loadables2-out.bin')
# Set up basic parameters with default values
params = {
'fit_addr' : 0x1000,
'kernel' : kernel,
'kernel_out' : kernel_out,
'kernel_addr' : 0x40000,
'kernel_size' : filesize(kernel),
'fdt' : fdt,
'fdt_out' : fdt_out,
'fdt_addr' : 0x80000,
'fdt_size' : filesize(control_dtb),
'fdt_load' : '',
'ramdisk' : ramdisk,
'ramdisk_out' : ramdisk_out,
'ramdisk_addr' : 0xc0000,
'ramdisk_size' : filesize(ramdisk),
'ramdisk_load' : '',
'ramdisk_config' : '',
'loadables1' : loadables1,
'loadables1_out' : loadables1_out,
'loadables1_addr' : 0x100000,
'loadables1_size' : filesize(loadables1),
'loadables1_load' : '',
'loadables2' : loadables2,
'loadables2_out' : loadables2_out,
'loadables2_addr' : 0x140000,
'loadables2_size' : filesize(loadables2),
'loadables2_load' : '',
'loadables_config' : '',
'compression' : 'none',
}
# Make a basic FIT and a script to load it
fit = make_fit(mkimage, params)
params['fit'] = fit
cmd = base_script % params
# First check that we can load a kernel
# We could perhaps reduce duplication with some loss of readability
cons.config.dtb = control_dtb
cons.restart_uboot()
with cons.log.section('Kernel load'):
output = cons.run_command_list(cmd.splitlines())
check_equal(kernel, kernel_out, 'Kernel not loaded')
check_not_equal(control_dtb, fdt_out,
'FDT loaded but should be ignored')
check_not_equal(ramdisk, ramdisk_out,
'Ramdisk loaded but should not be')
# Find out the offset in the FIT where U-Boot has found the FDT
line = find_matching(output, 'Booting using the fdt blob at ')
fit_offset = int(line, 16) - params['fit_addr']
fdt_magic = struct.pack('>L', 0xd00dfeed)
data = read_file(fit)
# Now find where it actually is in the FIT (skip the first word)
real_fit_offset = data.find(fdt_magic, 4)
assert fit_offset == real_fit_offset, (
'U-Boot loaded FDT from offset %#x, FDT is actually at %#x' %
(fit_offset, real_fit_offset))
# Now a kernel and an FDT
with cons.log.section('Kernel + FDT load'):
params['fdt_load'] = 'load = <%#x>;' % params['fdt_addr']
fit = make_fit(mkimage, params)
cons.restart_uboot()
output = cons.run_command_list(cmd.splitlines())
check_equal(kernel, kernel_out, 'Kernel not loaded')
check_equal(control_dtb, fdt_out, 'FDT not loaded')
check_not_equal(ramdisk, ramdisk_out,
'Ramdisk loaded but should not be')
# Try a ramdisk
with cons.log.section('Kernel + FDT + Ramdisk load'):
params['ramdisk_config'] = 'ramdisk = "ramdisk-1";'
params['ramdisk_load'] = 'load = <%#x>;' % params['ramdisk_addr']
fit = make_fit(mkimage, params)
cons.restart_uboot()
output = cons.run_command_list(cmd.splitlines())
check_equal(ramdisk, ramdisk_out, 'Ramdisk not loaded')
# Configuration with some Loadables
with cons.log.section('Kernel + FDT + Ramdisk load + Loadables'):
params['loadables_config'] = 'loadables = "kernel-2", "ramdisk-2";'
params['loadables1_load'] = ('load = <%#x>;' %
params['loadables1_addr'])
params['loadables2_load'] = ('load = <%#x>;' %
params['loadables2_addr'])
fit = make_fit(mkimage, params)
cons.restart_uboot()
output = cons.run_command_list(cmd.splitlines())
check_equal(loadables1, loadables1_out,
'Loadables1 (kernel) not loaded')
check_equal(loadables2, loadables2_out,
'Loadables2 (ramdisk) not loaded')
# Kernel, FDT and Ramdisk all compressed
with cons.log.section('(Kernel + FDT + Ramdisk) compressed'):
params['compression'] = 'gzip'
params['kernel'] = make_compressed(kernel)
params['fdt'] = make_compressed(fdt)
params['ramdisk'] = make_compressed(ramdisk)
fit = make_fit(mkimage, params)
cons.restart_uboot()
output = cons.run_command_list(cmd.splitlines())
check_equal(kernel, kernel_out, 'Kernel not loaded')
check_equal(control_dtb, fdt_out, 'FDT not loaded')
check_not_equal(ramdisk, ramdisk_out, 'Ramdisk got decompressed?')
check_equal(ramdisk + '.gz', ramdisk_out, 'Ramdist not loaded')
cons = u_boot_console
try:
# We need to use our own device tree file. Remember to restore it
# afterwards.
old_dtb = cons.config.dtb
mkimage = cons.config.build_dir + '/tools/mkimage'
run_fit_test(mkimage)
finally:
# Go back to the original U-Boot with the correct dtb.
cons.config.dtb = old_dtb
cons.restart_uboot()
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