Previously, when checking whether a CRT was revoked through
one of the configured CRLs, the library would only consider
those CRLs whose `issuer` field binary-matches the `subject`
field of the CA that has issued the CRT in question. If those
fields were not binary equivalent, the corresponding CRL was
discarded.
This is not in line with RFC 5280, which demands that the
comparison should be format- and case-insensitive. For example:
- If the same string is once encoded as a `PrintableString` and
another time as a `UTF8String`, they should compare equal.
- If two strings differ only in their choice of upper and lower case
letters, they should compare equal.
This commit fixes this by using the dedicated x509_name_cmp()
function to compare the CRL issuer with the CA subject.
Fixes#1784.
This commit introduces variants test-ca_utf8.crt,
test-ca_printablestring.crt and test-ca_uppercase.crt
of tests/data_files/test-ca.crt which differ from
test-ca.crt in their choice of string encoding and
upper and lower case letters in the DN field. These
changes should be immaterial to the recovation check,
and three tests are added that crl.pem, which applies
to test-ca.crt, is also considered as applying to
test-ca_*.crt.
The test files were generated using PR #1641 which
- adds a build instruction for test-ca.crt to
tests/data_files/Makefile which allows easy
change of the subject DN.
- changes the default string format from `PrintableString`
to `UTF8String`.
Specifically:
- `test-ca_utf8.crt` was generated by running
`rm test-ca.crt && make test-ca.crt`
on PR #1641.
- `test-ca_uppercase.crt`, too, was generated by running
`rm test-ca.crt && make test-ca.crt`
on PR #1641, after modifying the subject DN line in the build
instruction for `test-ca.crt` in `tests/data_files/Makefile`.
- `test-ca_printable.crt` is a copy of `test-ca.crt`
because at the time of this commit, `PrintableString` is
still the default string format.
stdio.h was being included both conditionally if MBEDTLS_FS_IO was
defined, and also unconditionally, which made at least one of them
redundant.
This change removes the unconditional inclusion of stdio.h and makes it
conditional on MBEDTLS_PLATFORM_C.
Context: This commit makes a change to mbedtls_pk_parse_key() which
is responsible for parsing of private keys. The function doesn't know
the key format in advance (PEM vs. DER, encrypted vs. unencrypted) and
tries them one by one, resetting the PK context in between.
Issue: The previous code resets the PK context through a call to
mbedtls_pk_free() along, lacking the accompanying mbedtls_pk_init()
call. Practically, this is not an issue because functionally
mbedtls_pk_free() + mbedtls_pk_init() is equivalent to mbedtls_pk_free()
with the current implementation of these functions, but strictly
speaking it's nonetheless a violation of the API semantics according
to which xxx_free() functions leave a context in uninitialized state.
(yet not entirely random, because xxx_free() functions must be idempotent,
so they cannot just fill the context they operate on with garbage).
Change: The commit adds calls to mbedtls_pk_init() after those calls
to mbedtls_pk_free() within mbedtls_pk_parse_key() after which the
PK context might still be used.
When a random number is generated for the Miller-Rabin primality test,
if the bit length of the random number is larger than the number being
tested, the random number is shifted right to have the same bit length.
This introduces bias, as the random number is now guaranteed to be
larger than 2^(bit length-1).
Changing this to instead zero all bits higher than the tested numbers
bit length will remove this bias and keep the random number being
uniformly generated.
Primality tests have to deal with different distribution when generating
primes and when validating primes.
These new tests are testing if mbedtls_mpi_is_prime() is working
properly in the latter setting.
The new tests involve pseudoprimes with maximum number of
non-witnesses. The non-witnesses were generated by printing them
from mpi_miller_rabin(). The pseudoprimes were generated by the
following function:
void gen_monier( mbedtls_mpi* res, int nbits )
{
mbedtls_mpi p_2x_plus_1, p_4x_plus_1, x, tmp;
mbedtls_mpi_init( &p_2x_plus_1 );
mbedtls_mpi_init( &p_4x_plus_1 );
mbedtls_mpi_init( &x ); mbedtls_mpi_init( &tmp );
do
{
mbedtls_mpi_gen_prime( &p_2x_plus_1, nbits >> 1, 0,
rnd_std_rand, NULL );
mbedtls_mpi_sub_int( &x, &p_2x_plus_1, 1 );
mbedtls_mpi_div_int( &x, &tmp, &x, 2 );
if( mbedtls_mpi_get_bit( &x, 0 ) == 0 )
continue;
mbedtls_mpi_mul_int( &p_4x_plus_1, &x, 4 );
mbedtls_mpi_add_int( &p_4x_plus_1, &p_4x_plus_1, 1 );
if( mbedtls_mpi_is_prime( &p_4x_plus_1, rnd_std_rand,
NULL ) == 0 )
break;
} while( 1 );
mbedtls_mpi_mul_mpi( res, &p_2x_plus_1, &p_4x_plus_1 );
}
When MBEDTLS_MEMORY_BUFFER_ALLOC_C was defined, the sample ssl_server2.c was
using its own memory buffer for memory allocated by the library. The memory
used wasn't obvious, so this adds a macro for the memory buffer allocated to
make the allocated memory size more obvious and hence easier to configure.
Newer features in the library have increased the overall RAM usage of the
library, when all features are enabled. ssl_server2.c, with all features enabled
was running out of memory for the ssl-opt.sh test 'Authentication: client
max_int chain, server required'.
This commit increases the memory buffer allocation for ssl_server2.c to allow
the test to work with all features enabled.
This commit changes the behavior of the record decryption routine
`ssl_decrypt_buf()` in the following situation:
1. A CBC ciphersuite with Encrypt-then-MAC is used.
2. A record with valid MAC but invalid CBC padding is received.
In this situation, the previous code would not raise and error but
instead forward the decrypted packet, including the wrong padding,
to the user.
This commit changes this behavior to return the error
MBEDTLS_ERR_SSL_INVALID_MAC instead.
While erroneous, the previous behavior does not constitute a
security flaw since it can only happen for properly authenticated
records, that is, if the peer makes a mistake while preparing the
padded plaintext.
This commit ensures that buffers holding fragmented or
handshake messages get zeroized before they are freed
when the respective handshake message is no longer needed.
Previously, the handshake message content would leak on
the heap.
This commit replaces multiple `memset()` calls in the example
programs aes/aescrypt2.c and aes/crypt_and_hash.c by calls to
the reliable zeroization function `mbedtls_zeroize()`.
While not a security issue because the code is in the example
programs, it's bad practice and should be fixed.
The input distribution to primality testing functions is completely
different when used for generating primes and when for validating
primes. The constants used in the library are geared towards the prime
generation use case and are weak when used for validation. (Maliciously
constructed composite numbers can pass the test with high probability)
The mbedtls_mpi_is_prime() function is in the public API and although it
is not documented, it is reasonable to assume that the primary use case
is validating primes. The RSA module too uses it for validating key
material.
