mbedtls/scripts/generate_psa_constants.py
Gilles Peskine f65ed6f254 Change key types to a 16-bit encoding
All key types now have an encoding on 32 bits where the bottom 16 bits
are zero. Change to using 16 bits only.

Keep 32 bits for key types in storage, but move the significant
half-word from the top to the bottom.

Likewise, change EC curve and DH group families from 32 bits out of
which the top 8 and bottom 16 bits are zero, to 8 bits only.

Reorder psa_core_key_attributes_t to avoid padding.
2020-01-31 10:24:21 +01:00

401 lines
15 KiB
Python
Executable File

#!/usr/bin/env python3
"""Generate programs/psa/psa_constant_names_generated.c
which is included by programs/psa/psa_constant_names.c.
The code generated by this module is only meant to be used in the context
of that program.
"""
import os
import re
OUTPUT_TEMPLATE = '''\
/* Automatically generated by generate_psa_constant.py. DO NOT EDIT. */
static const char *psa_strerror(psa_status_t status)
{
switch (status) {
%(status_cases)s
default: return NULL;
}
}
static const char *psa_ecc_curve_name(psa_ecc_curve_t curve)
{
switch (curve) {
%(ecc_curve_cases)s
default: return NULL;
}
}
static const char *psa_dh_group_name(psa_dh_group_t group)
{
switch (group) {
%(dh_group_cases)s
default: return NULL;
}
}
static const char *psa_hash_algorithm_name(psa_algorithm_t hash_alg)
{
switch (hash_alg) {
%(hash_algorithm_cases)s
default: return NULL;
}
}
static const char *psa_ka_algorithm_name(psa_algorithm_t ka_alg)
{
switch (ka_alg) {
%(ka_algorithm_cases)s
default: return NULL;
}
}
static int psa_snprint_key_type(char *buffer, size_t buffer_size,
psa_key_type_t type)
{
size_t required_size = 0;
switch (type) {
%(key_type_cases)s
default:
%(key_type_code)s{
return snprintf(buffer, buffer_size,
"0x%%04x", (unsigned) type);
}
break;
}
buffer[0] = 0;
return (int) required_size;
}
#define NO_LENGTH_MODIFIER 0xfffffffflu
static int psa_snprint_algorithm(char *buffer, size_t buffer_size,
psa_algorithm_t alg)
{
size_t required_size = 0;
psa_algorithm_t core_alg = alg;
unsigned long length_modifier = NO_LENGTH_MODIFIER;
if (PSA_ALG_IS_MAC(alg)) {
core_alg = PSA_ALG_TRUNCATED_MAC(alg, 0);
if (core_alg != alg) {
append(&buffer, buffer_size, &required_size,
"PSA_ALG_TRUNCATED_MAC(", 22);
length_modifier = PSA_MAC_TRUNCATED_LENGTH(alg);
}
} else if (PSA_ALG_IS_AEAD(alg)) {
core_alg = PSA_ALG_AEAD_WITH_DEFAULT_TAG_LENGTH(alg);
if (core_alg == 0) {
/* For unknown AEAD algorithms, there is no "default tag length". */
core_alg = alg;
} else if (core_alg != alg) {
append(&buffer, buffer_size, &required_size,
"PSA_ALG_AEAD_WITH_TAG_LENGTH(", 29);
length_modifier = PSA_AEAD_TAG_LENGTH(alg);
}
} else if (PSA_ALG_IS_KEY_AGREEMENT(alg) &&
!PSA_ALG_IS_RAW_KEY_AGREEMENT(alg)) {
core_alg = PSA_ALG_KEY_AGREEMENT_GET_KDF(alg);
append(&buffer, buffer_size, &required_size,
"PSA_ALG_KEY_AGREEMENT(", 22);
append_with_alg(&buffer, buffer_size, &required_size,
psa_ka_algorithm_name,
PSA_ALG_KEY_AGREEMENT_GET_BASE(alg));
append(&buffer, buffer_size, &required_size, ", ", 2);
}
switch (core_alg) {
%(algorithm_cases)s
default:
%(algorithm_code)s{
append_integer(&buffer, buffer_size, &required_size,
"0x%%08lx", (unsigned long) core_alg);
}
break;
}
if (core_alg != alg) {
if (length_modifier != NO_LENGTH_MODIFIER) {
append(&buffer, buffer_size, &required_size, ", ", 2);
append_integer(&buffer, buffer_size, &required_size,
"%%lu", length_modifier);
}
append(&buffer, buffer_size, &required_size, ")", 1);
}
buffer[0] = 0;
return (int) required_size;
}
static int psa_snprint_key_usage(char *buffer, size_t buffer_size,
psa_key_usage_t usage)
{
size_t required_size = 0;
if (usage == 0) {
if (buffer_size > 1) {
buffer[0] = '0';
buffer[1] = 0;
} else if (buffer_size == 1) {
buffer[0] = 0;
}
return 1;
}
%(key_usage_code)s
if (usage != 0) {
if (required_size != 0) {
append(&buffer, buffer_size, &required_size, " | ", 3);
}
append_integer(&buffer, buffer_size, &required_size,
"0x%%08lx", (unsigned long) usage);
} else {
buffer[0] = 0;
}
return (int) required_size;
}
/* End of automatically generated file. */
'''
KEY_TYPE_FROM_CURVE_TEMPLATE = '''if (%(tester)s(type)) {
append_with_curve(&buffer, buffer_size, &required_size,
"%(builder)s", %(builder_length)s,
PSA_KEY_TYPE_GET_CURVE(type));
} else '''
KEY_TYPE_FROM_GROUP_TEMPLATE = '''if (%(tester)s(type)) {
append_with_group(&buffer, buffer_size, &required_size,
"%(builder)s", %(builder_length)s,
PSA_KEY_TYPE_GET_GROUP(type));
} else '''
ALGORITHM_FROM_HASH_TEMPLATE = '''if (%(tester)s(core_alg)) {
append(&buffer, buffer_size, &required_size,
"%(builder)s(", %(builder_length)s + 1);
append_with_alg(&buffer, buffer_size, &required_size,
psa_hash_algorithm_name,
PSA_ALG_GET_HASH(core_alg));
append(&buffer, buffer_size, &required_size, ")", 1);
} else '''
BIT_TEST_TEMPLATE = '''\
if (%(var)s & %(flag)s) {
if (required_size != 0) {
append(&buffer, buffer_size, &required_size, " | ", 3);
}
append(&buffer, buffer_size, &required_size, "%(flag)s", %(length)d);
%(var)s ^= %(flag)s;
}\
'''
class MacroCollector:
"""Collect PSA crypto macro definitions from C header files.
1. Call `read_file` on the input header file(s).
2. Call `write_file` to write ``psa_constant_names_generated.c``.
"""
def __init__(self):
self.statuses = set()
self.key_types = set()
self.key_types_from_curve = {}
self.key_types_from_group = {}
self.ecc_curves = set()
self.dh_groups = set()
self.algorithms = set()
self.hash_algorithms = set()
self.ka_algorithms = set()
self.algorithms_from_hash = {}
self.key_usages = set()
# "#define" followed by a macro name with either no parameters
# or a single parameter and a non-empty expansion.
# Grab the macro name in group 1, the parameter name if any in group 2
# and the expansion in group 3.
_define_directive_re = re.compile(r'\s*#\s*define\s+(\w+)' +
r'(?:\s+|\((\w+)\)\s*)' +
r'(.+)')
_deprecated_definition_re = re.compile(r'\s*MBEDTLS_DEPRECATED')
def read_line(self, line):
"""Parse a C header line and record the PSA identifier it defines if any.
This function analyzes lines that start with "#define PSA_"
(up to non-significant whitespace) and skips all non-matching lines.
"""
# pylint: disable=too-many-branches
m = re.match(self._define_directive_re, line)
if not m:
return
name, parameter, expansion = m.groups()
expansion = re.sub(r'/\*.*?\*/|//.*', r' ', expansion)
if re.match(self._deprecated_definition_re, expansion):
# Skip deprecated values, which are assumed to be
# backward compatibility aliases that share
# numerical values with non-deprecated values.
return
if name.endswith('_FLAG') or name.endswith('MASK'):
# Macro only to build actual values
return
elif (name.startswith('PSA_ERROR_') or name == 'PSA_SUCCESS') \
and not parameter:
self.statuses.add(name)
elif name.startswith('PSA_KEY_TYPE_') and not parameter:
self.key_types.add(name)
elif name.startswith('PSA_KEY_TYPE_') and parameter == 'curve':
self.key_types_from_curve[name] = name[:13] + 'IS_' + name[13:]
elif name.startswith('PSA_KEY_TYPE_') and parameter == 'group':
self.key_types_from_group[name] = name[:13] + 'IS_' + name[13:]
elif name.startswith('PSA_ECC_CURVE_') and not parameter:
self.ecc_curves.add(name)
elif name.startswith('PSA_DH_GROUP_') and not parameter:
self.dh_groups.add(name)
elif name.startswith('PSA_ALG_') and not parameter:
if name in ['PSA_ALG_ECDSA_BASE',
'PSA_ALG_RSA_PKCS1V15_SIGN_BASE']:
# Ad hoc skipping of duplicate names for some numerical values
return
self.algorithms.add(name)
# Ad hoc detection of hash algorithms
if re.search(r'0x010000[0-9A-Fa-f]{2}', expansion):
self.hash_algorithms.add(name)
# Ad hoc detection of key agreement algorithms
if re.search(r'0x30[0-9A-Fa-f]{2}0000', expansion):
self.ka_algorithms.add(name)
elif name.startswith('PSA_ALG_') and parameter == 'hash_alg':
if name in ['PSA_ALG_DSA', 'PSA_ALG_ECDSA']:
# A naming irregularity
tester = name[:8] + 'IS_RANDOMIZED_' + name[8:]
else:
tester = name[:8] + 'IS_' + name[8:]
self.algorithms_from_hash[name] = tester
elif name.startswith('PSA_KEY_USAGE_') and not parameter:
self.key_usages.add(name)
else:
# Other macro without parameter
return
_nonascii_re = re.compile(rb'[^\x00-\x7f]+')
_continued_line_re = re.compile(rb'\\\r?\n\Z')
def read_file(self, header_file):
for line in header_file:
m = re.search(self._continued_line_re, line)
while m:
cont = next(header_file)
line = line[:m.start(0)] + cont
m = re.search(self._continued_line_re, line)
line = re.sub(self._nonascii_re, rb'', line).decode('ascii')
self.read_line(line)
@staticmethod
def _make_return_case(name):
return 'case %(name)s: return "%(name)s";' % {'name': name}
@staticmethod
def _make_append_case(name):
template = ('case %(name)s: '
'append(&buffer, buffer_size, &required_size, "%(name)s", %(length)d); '
'break;')
return template % {'name': name, 'length': len(name)}
@staticmethod
def _make_bit_test(var, flag):
return BIT_TEST_TEMPLATE % {'var': var,
'flag': flag,
'length': len(flag)}
def _make_status_cases(self):
return '\n '.join(map(self._make_return_case,
sorted(self.statuses)))
def _make_ecc_curve_cases(self):
return '\n '.join(map(self._make_return_case,
sorted(self.ecc_curves)))
def _make_dh_group_cases(self):
return '\n '.join(map(self._make_return_case,
sorted(self.dh_groups)))
def _make_key_type_cases(self):
return '\n '.join(map(self._make_append_case,
sorted(self.key_types)))
@staticmethod
def _make_key_type_from_curve_code(builder, tester):
return KEY_TYPE_FROM_CURVE_TEMPLATE % {'builder': builder,
'builder_length': len(builder),
'tester': tester}
@staticmethod
def _make_key_type_from_group_code(builder, tester):
return KEY_TYPE_FROM_GROUP_TEMPLATE % {'builder': builder,
'builder_length': len(builder),
'tester': tester}
def _make_ecc_key_type_code(self):
d = self.key_types_from_curve
make = self._make_key_type_from_curve_code
return ''.join([make(k, d[k]) for k in sorted(d.keys())])
def _make_dh_key_type_code(self):
d = self.key_types_from_group
make = self._make_key_type_from_group_code
return ''.join([make(k, d[k]) for k in sorted(d.keys())])
def _make_hash_algorithm_cases(self):
return '\n '.join(map(self._make_return_case,
sorted(self.hash_algorithms)))
def _make_ka_algorithm_cases(self):
return '\n '.join(map(self._make_return_case,
sorted(self.ka_algorithms)))
def _make_algorithm_cases(self):
return '\n '.join(map(self._make_append_case,
sorted(self.algorithms)))
@staticmethod
def _make_algorithm_from_hash_code(builder, tester):
return ALGORITHM_FROM_HASH_TEMPLATE % {'builder': builder,
'builder_length': len(builder),
'tester': tester}
def _make_algorithm_code(self):
d = self.algorithms_from_hash
make = self._make_algorithm_from_hash_code
return ''.join([make(k, d[k]) for k in sorted(d.keys())])
def _make_key_usage_code(self):
return '\n'.join([self._make_bit_test('usage', bit)
for bit in sorted(self.key_usages)])
def write_file(self, output_file):
"""Generate the pretty-printer function code from the gathered
constant definitions.
"""
data = {}
data['status_cases'] = self._make_status_cases()
data['ecc_curve_cases'] = self._make_ecc_curve_cases()
data['dh_group_cases'] = self._make_dh_group_cases()
data['key_type_cases'] = self._make_key_type_cases()
data['key_type_code'] = (self._make_ecc_key_type_code() +
self._make_dh_key_type_code())
data['hash_algorithm_cases'] = self._make_hash_algorithm_cases()
data['ka_algorithm_cases'] = self._make_ka_algorithm_cases()
data['algorithm_cases'] = self._make_algorithm_cases()
data['algorithm_code'] = self._make_algorithm_code()
data['key_usage_code'] = self._make_key_usage_code()
output_file.write(OUTPUT_TEMPLATE % data)
def generate_psa_constants(header_file_names, output_file_name):
collector = MacroCollector()
for header_file_name in header_file_names:
with open(header_file_name, 'rb') as header_file:
collector.read_file(header_file)
temp_file_name = output_file_name + '.tmp'
with open(temp_file_name, 'w') as output_file:
collector.write_file(output_file)
os.rename(temp_file_name, output_file_name)
if __name__ == '__main__':
if not os.path.isdir('programs') and os.path.isdir('../programs'):
os.chdir('..')
generate_psa_constants(['include/psa/crypto_values.h',
'include/psa/crypto_extra.h'],
'programs/psa/psa_constant_names_generated.c')