Move asn1_skip_integer to the asn1_helpers module

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2021-02-13 00:25:53 +01:00
parent 57948369c4
commit 8e94efe4ba
3 changed files with 86 additions and 56 deletions

View File

@ -22,5 +22,29 @@
#include "test/helpers.h"
/** Skip past an INTEGER in an ASN.1 buffer.
*
* Mark the current test case as failed in any of the following conditions:
* - The buffer does not start with an ASN.1 INTEGER.
* - The integer's size or parity does not match the constraints expressed
* through \p min_bits, \p max_bits and \p must_be_odd.
*
* \param p Upon entry, `*p` points to the first byte of the
* buffer to parse.
* On successful return, `*p` points to the first byte
* after the parsed INTEGER.
* On failure, `*p` is unspecified.
* \param end The end of the ASN.1 buffer.
* \param min_bits Fail the test case if the integer does not have at
* least this many significant bits.
* \param max_bits Fail the test case if the integer has more than
* this many significant bits.
* \param must_be_odd Fail the test case if the integer is even.
*
* \return \c 0 if the test failed, otherwise 1.
*/
int mbedtls_test_asn1_skip_integer( unsigned char **p, const unsigned char *end,
size_t min_bits, size_t max_bits,
int must_be_odd );
#endif /* ASN1_HELPERS_H */

View File

@ -23,3 +23,52 @@
#include <test/helpers.h>
#include <test/macros.h>
#if defined(MBEDTLS_ASN1_PARSE_C)
#include <mbedtls/asn1.h>
int mbedtls_test_asn1_skip_integer( unsigned char **p, const unsigned char *end,
size_t min_bits, size_t max_bits,
int must_be_odd )
{
size_t len;
size_t actual_bits;
unsigned char msb;
TEST_EQUAL( mbedtls_asn1_get_tag( p, end, &len,
MBEDTLS_ASN1_INTEGER ),
0 );
/* Check if the retrieved length doesn't extend the actual buffer's size.
* It is assumed here, that end >= p, which validates casting to size_t. */
TEST_ASSERT( len <= (size_t)( end - *p) );
/* Tolerate a slight departure from DER encoding:
* - 0 may be represented by an empty string or a 1-byte string.
* - The sign bit may be used as a value bit. */
if( ( len == 1 && ( *p )[0] == 0 ) ||
( len > 1 && ( *p )[0] == 0 && ( ( *p )[1] & 0x80 ) != 0 ) )
{
++( *p );
--len;
}
if( min_bits == 0 && len == 0 )
return( 1 );
msb = ( *p )[0];
TEST_ASSERT( msb != 0 );
actual_bits = 8 * ( len - 1 );
while( msb != 0 )
{
msb >>= 1;
++actual_bits;
}
TEST_ASSERT( actual_bits >= min_bits );
TEST_ASSERT( actual_bits <= max_bits );
if( must_be_odd )
TEST_ASSERT( ( ( *p )[len-1] & 1 ) != 0 );
*p += len;
return( 1 );
exit:
return( 0 );
}
#endif /* MBEDTLS_ASN1_PARSE_C */

View File

@ -12,6 +12,7 @@
#include "psa/crypto.h"
#include "psa_crypto_slot_management.h"
#include "test/asn1_helpers.h"
#include "test/psa_crypto_helpers.h"
/** An invalid export length that will never be set by psa_export_key(). */
@ -818,50 +819,6 @@ exit:
return( ok );
}
int asn1_skip_integer( unsigned char **p, const unsigned char *end,
size_t min_bits, size_t max_bits,
int must_be_odd )
{
size_t len;
size_t actual_bits;
unsigned char msb;
TEST_EQUAL( mbedtls_asn1_get_tag( p, end, &len,
MBEDTLS_ASN1_INTEGER ),
0 );
/* Check if the retrieved length doesn't extend the actual buffer's size.
* It is assumed here, that end >= p, which validates casting to size_t. */
TEST_ASSERT( len <= (size_t)( end - *p) );
/* Tolerate a slight departure from DER encoding:
* - 0 may be represented by an empty string or a 1-byte string.
* - The sign bit may be used as a value bit. */
if( ( len == 1 && ( *p )[0] == 0 ) ||
( len > 1 && ( *p )[0] == 0 && ( ( *p )[1] & 0x80 ) != 0 ) )
{
++( *p );
--len;
}
if( min_bits == 0 && len == 0 )
return( 1 );
msb = ( *p )[0];
TEST_ASSERT( msb != 0 );
actual_bits = 8 * ( len - 1 );
while( msb != 0 )
{
msb >>= 1;
++actual_bits;
}
TEST_ASSERT( actual_bits >= min_bits );
TEST_ASSERT( actual_bits <= max_bits );
if( must_be_odd )
TEST_ASSERT( ( ( *p )[len-1] & 1 ) != 0 );
*p += len;
return( 1 );
exit:
return( 0 );
}
int mbedtls_test_psa_exported_key_sanity_check(
psa_key_type_t type, size_t bits,
uint8_t *exported, size_t exported_length )
@ -913,25 +870,25 @@ int mbedtls_test_psa_exported_key_sanity_check(
MBEDTLS_ASN1_SEQUENCE |
MBEDTLS_ASN1_CONSTRUCTED ), 0 );
TEST_EQUAL( p + len, end );
if( ! asn1_skip_integer( &p, end, 0, 0, 0 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, 0, 0, 0 ) )
goto exit;
if( ! asn1_skip_integer( &p, end, bits, bits, 1 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) )
goto exit;
if( ! asn1_skip_integer( &p, end, 2, bits, 1 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, 2, bits, 1 ) )
goto exit;
/* Require d to be at least half the size of n. */
if( ! asn1_skip_integer( &p, end, bits / 2, bits, 1 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, bits / 2, bits, 1 ) )
goto exit;
/* Require p and q to be at most half the size of n, rounded up. */
if( ! asn1_skip_integer( &p, end, bits / 2, bits / 2 + 1, 1 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, bits / 2, bits / 2 + 1, 1 ) )
goto exit;
if( ! asn1_skip_integer( &p, end, bits / 2, bits / 2 + 1, 1 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, bits / 2, bits / 2 + 1, 1 ) )
goto exit;
if( ! asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
goto exit;
if( ! asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
goto exit;
if( ! asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
goto exit;
TEST_EQUAL( p, end );
}
@ -964,9 +921,9 @@ int mbedtls_test_psa_exported_key_sanity_check(
MBEDTLS_ASN1_CONSTRUCTED ),
0 );
TEST_EQUAL( p + len, end );
if( ! asn1_skip_integer( &p, end, bits, bits, 1 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) )
goto exit;
if( ! asn1_skip_integer( &p, end, 2, bits, 1 ) )
if( ! mbedtls_test_asn1_skip_integer( &p, end, 2, bits, 1 ) )
goto exit;
TEST_EQUAL( p, end );
}
@ -5632,7 +5589,7 @@ void generate_key_rsa( int bits_arg,
TEST_EQUAL( 0, mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_SEQUENCE |
MBEDTLS_ASN1_CONSTRUCTED ) );
TEST_ASSERT( asn1_skip_integer( &p, end, bits, bits, 1 ) );
TEST_ASSERT( mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) );
TEST_EQUAL( 0, mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_INTEGER ) );
if( len >= 1 && p[0] == 0 )