- Explain the use of explicit ASN.1 tagging for the extensions structuree
- Remove misleading comment which suggests that mbedtls_x509_get_ext()
also parsed the header of the first extension, which is not the case.
Some functions within the X.509 module return an ASN.1 low level
error code where instead this error code should be wrapped by a
high-level X.509 error code as in the bulk of the module.
Specifically, the following functions are affected:
- mbedtls_x509_get_ext()
- x509_get_version()
- x509_get_uid()
This commit modifies these functions to always return an
X.509 high level error code.
Care has to be taken when adapting `mbetls_x509_get_ext()`:
Currently, the callers `mbedtls_x509_crt_ext()` treat the
return code `MBEDTLS_ERR_ASN1_UNEXPECTED_TAG` specially to
gracefully detect and continue if the extension structure is not
present. Wrapping the ASN.1 error with
`MBEDTLS_ERR_X509_INVALID_EXTENSIONS` and adapting the check
accordingly would mean that an unexpected tag somewhere
down the extension parsing would be ignored by the caller.
The way out of this is the following: Luckily, the extension
structure is always the last field in the surrounding structure,
so if there is some data remaining, it must be an Extension
structure, so we don't need to deal with a tag mismatch gracefully
in the first place.
We may therefore wrap the return code from the initial call to
`mbedtls_asn1_get_tag()` in `mbedtls_x509_get_ext()` by
`MBEDTLS_ERR_X509_INVALID_EXTENSIONS` and simply remove
the special treatment of `MBEDTLS_ERR_ASN1_UNEXPECTED_TAG`
in the callers `x509_crl_get_ext()` and `x509_crt_get_ext()`.
This renders `mbedtls_x509_get_ext()` unsuitable if it ever
happened that an Extension structure is optional and does not
occur at the end of its surrounding structure, but for CRTs
and CRLs, it's fine.
The following tests need to be adapted:
- "TBSCertificate v3, issuerID wrong tag"
The issuerID is optional, so if we look for its presence
but find a different tag, we silently continue and try
parsing the subjectID, and then the extensions. The tag '00'
used in this test doesn't match either of these, and the
previous code would hence return LENGTH_MISMATCH after
unsucessfully trying issuerID, subjectID and Extensions.
With the new code, any data remaining after issuerID and
subjectID _must_ be Extension data, so we fail with
UNEXPECTED_TAG when trying to parse the Extension data.
- "TBSCertificate v3, UIDs, invalid length"
The test hardcodes the expectation of
MBEDTLS_ERR_ASN1_INVALID_LENGTH, which needs to be
wrapped in MBEDTLS_ERR_X509_INVALID_FORMAT now.
Fixes#2431.
When parsing a substructure of an ASN.1 structure, no field within
the substructure must exceed the bounds of the substructure.
Concretely, the `end` pointer passed to the ASN.1 parsing routines
must be updated to point to the end of the substructure while parsing
the latter.
This was previously not the case for the routines
- x509_get_attr_type_and_value(),
- mbedtls_x509_get_crt_ext(),
- mbedtls_x509_get_crl_ext().
These functions kept using the end of the parent structure as the
`end` pointer and would hence allow substructure fields to cross
the substructure boundary. This could lead to successful parsing
of ill-formed X.509 CRTs.
This commit fixes this.
Care has to be taken when adapting `mbedtls_x509_get_crt_ext()`
and `mbedtls_x509_get_crl_ext()`, as the underlying function
`mbedtls_x509_get_ext()` returns `0` if no extensions are present
but doesn't set the variable which holds the bounds of the Extensions
structure in case the latter is present. This commit addresses
this by returning early from `mbedtls_x509_get_crt_ext()` and
`mbedtls_x509_get_crl_ext()` if parsing has reached the end of
the input buffer.
The following X.509 parsing tests need to be adapted:
- "TBSCertificate, issuer two inner set datas"
This test exercises the X.509 CRT parser with a Subject name
which has two empty `AttributeTypeAndValue` structures.
This is supposed to fail with `MBEDTLS_ERR_ASN1_OUT_OF_DATA`
because the parser should attempt to parse the first structure
and fail because of a lack of data. Previously, it failed to
obey the (0-length) bounds of the first AttributeTypeAndValue
structure and would try to interpret the beginning of the second
AttributeTypeAndValue structure as the first field of the first
AttributeTypeAndValue structure, returning an UNEXPECTED_TAG error.
- "TBSCertificate, issuer, no full following string"
This test exercises the parser's behaviour on an AttributeTypeAndValue
structure which contains more data than expected; it should therefore
fail with MBEDTLS_ERR_ASN1_LENGTH_MISMATCH. Because of the missing bounds
check, it previously failed with UNEXPECTED_TAG because it interpreted
the remaining byte in the first AttributeTypeAndValue structure as the
first byte in the second AttributeTypeAndValue structure.
- "SubjectAltName repeated"
This test should exercise two SubjectAltNames extensions in succession,
but a wrong length values makes the second SubjectAltNames extension appear
outside of the Extensions structure. With the new bounds in place, this
therefore fails with a LENGTH_MISMATCH error. This commit adapts the test
data to put the 2nd SubjectAltNames extension inside the Extensions
structure, too.
* origin/pr/2403: (24 commits)
crypto: Update to Mbed Crypto 8907b019e7
Create seedfile before running tests
crypto: Update to Mbed Crypto 81f9539037
ssl_cli.c : add explicit casting to unsigned char
Generating visualc files - let Mbed TLS take precedence over crypto
Add a link to the seedfile for out-of-tree cmake builds
Adjust visual studio file generation to always use the crypto submodule
all.sh: unparallelize mingw tests
all.sh - disable parallelization for shared target tests
config.pl: disable PSA_ITS_FILE and PSA_CRYPTO_STORAGE for baremetal
all.sh: unset crypto storage define in a psa full config cmake asan test
all.sh: unset FS_IO-dependent defines for tests that do not have it
curves.pl - change test script to not depend on the implementation
Export the submodule flag to sub-cmakes
Disable MBEDTLS_ECP_RESTARTABLE in full config
Export the submodule flag to sub-makes
Force the usage of crypto submodule
Fix crypto submodule usage in Makefile
Documentation rewording
Typo fixes in documentation
...
Signal casting from size_t to unsigned char explicitly, so that the compiler
does not raise a warning about possible loss of data on MSVC, targeting
64-bit Windows.
The guard for the definition of the function was different from the guard on
its only use - make it the same.
This has been caught by tests/scripts/key-exchanges.pl. It had not been caught
by this script in earlier CI runs, because previously USE_PSA_CRYPTO was
disabled in the builds used by this script; enabling it uncovered the issue.
Adapt tests in all.sh:
- tests with submodule enabled (default) no longer need to enable it
explicitly, and no longer need runtime tests, as those are now handled by
all other test cases in this script
- tests with submodule disabled (old default) now need to disable it
explicitly, and execute some runtime tests, as those are no longer tested
anywhere else in this script
Adapt documentation in Readme: remove the section "building with submodule"
and replace it with a new section before the other building sections.
Purposefully don't document how to build not from the submodule, as that
option is going away soon.
Set the next sequence of the subject_alt_name to NULL when deleting
sequence on failure in `get_subject_alt_name()`.
Found by Philippe Antoine. Credit to OSS-Fuzz.
* origin/pr/2530: (27 commits)
Style fix
Fix test data
Update test data
Add some negative test cases
Fix minor issues
Add ChangeLog entry about listing all SAN
Check that SAN is not malformed when parsing
Documentation fixes
Fix ChangeLog entry
Fail in case critical crt policy not supported
Update SAN parsing documentation
change the type of hardware_module_name member
Change mbedtls_x509_subject_alternative_name
Add length checking in certificate policy parsing
Rephrase x509_crt extension member description
Rephrase changeLog entries
Remove redundant memset()
Propogate error when parsing SubjectAltNames
Tidy up style in x509_info_subject_alt_name
Print unparseable SubjectAlternativeNames
...
* origin/pr/2538:
Remove unneeded whitespaces
Fix mingw CI failures
Initialize psa_crypto in ssl test
Fix missing tls version test failures
Fix typo
Fix ChangeLog entry location
Add changeLog entry
Add test for export keys functionality
Add function to retrieve the tls_prf type
Add tests for the public tls_prf API
Add public API for tls_prf
Add eap-tls key derivation in the examples.
Add ChangeLog entry
Add an extra key export function
Have the temporary buffer allocated dynamically
Zeroize secret data in the exit point
Add a single exit point in key derivation function
Add an additional function `mbedtls_ssl_export_keys_ext_t()`
for exporting key, that adds additional information such as
the used `tls_prf` and the random bytes.
In case the certificate policy is not of type `AnyPolicy`
set the returned error code to `MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE`
and continue parsing. If the extension is critical, return error anyway,
unless `MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION` is configured.
Fail parsing on any other error.
Make `mbedtls_x509_subject_alternative_name` to be a single item
rather than a list. Adapt the subject alternative name parsing function,
to receive a signle `mbedtls_x509_buf` item from the subject_alt_names
sequence of the certificate.
The preceding calloc() already zeroizes that memory area, therfore the
memset() is not necessary. Compilers are likely to optimize this out,
but it still can be confusing to readers.
The previous behaviour of mbedtls_x509_parse_subject_alternative_name()
was to silently ignore errors coming from x509_get_other_name(). The
current commit fixes it and returns with an error.
In x509_info_subject_alt_name() we silently dropped names that we
couldn't parse because they are not supported or are malformed. (Being
malformed might mean damaged file, but can be a sign of incompatibility
between applications.)
This commit adds code notifying the user that there is something, but
we can't parse it.
Lengths are aleady checked in mbedtls_asn1_get_len() which is called in
mbedtls_asn1_get_tag(), therefore it is not necessary to check
the lengths explicitly afterwards.
Also with the previous flow data was left in the output buffer on some
errors.
* origin/pr/1633: (26 commits)
Fix uninitialized variable access in debug output of record enc/dec
Adapt PSA code to ssl_transform changes
Ensure non-NULL key buffer when building SSL test transforms
Catch errors while building SSL test transforms
Use mbedtls_{calloc|free}() in SSL unit test suite
Improve documentation of mbedtls_record
Adapt record length value after encryption
Alternative between send/recv transform in SSL record test suite
Fix memory leak on failure in test_suite_ssl
Rename ssl_decrypt_buf() to mbedtls_ssl_decrypt_buf() in comment
Add record encryption/decryption tests for ARIA to SSL test suite
Improve documentation of mbedtls_ssl_transform
Double check that record expansion is as expected during decryption
Move debugging output after record decryption
Add encryption/decryption tests for small records
Add tests for record encryption/decryption
Reduce size of `ssl_transform` if no MAC ciphersuite is enabled
Remove code from `ssl_derive_keys` if relevant modes are not enabled
Provide standalone version of `ssl_decrypt_buf`
Provide standalone version of `ssl_encrypt_buf`
...
Autogenerate errors.c There are changes in error.c due to updating the
crypto submodule to a version that no longer has the SSL, X.509, or net
modules. The errors are correctly sourced from Mbed TLS and not Mbed
Crypto, but they do move around within the file due to how the error
generator script is written.
This commit adds tests exercising mutually inverse pairs of
record encryption and decryption transformations for the various
transformation types allowed in TLS: Stream, CBC, and AEAD.
The hash contexts `ssl_transform->md_ctx_{enc/dec}` are not used if
only AEAD ciphersuites are enabled. This commit removes them from the
`ssl_transform` struct in this case, saving a few bytes.
This commit guards code specific to AEAD, CBC and stream cipher modes
in `ssl_derive_keys` by the respective configuration flags, analogous
to the guards that are already in place in the record decryption and
encryption functions `ssl_decrypt_buf` resp. `ssl_decrypt_buf`.
Analogous to the previous commit, but concerning the record decryption
routine `ssl_decrypt_buf`.
An important change regards the checking of CBC padding:
Prior to this commit, the CBC padding check always read 256 bytes at
the end of the internal record buffer, almost always going past the
boundaries of the record under consideration. In order to stay within
the bounds of the given record, this commit changes this behavior by
always reading the last min(256, plaintext_len) bytes of the record
plaintext buffer and taking into consideration the last `padlen` of
these for the padding check. With this change, the memory access
pattern and runtime of the padding check is entirely determined by
the size of the encrypted record, in particular not giving away
any information on the validity of the padding.
The following depicts the different behaviors:
1) Previous CBC padding check
1.a) Claimed padding length <= plaintext length
+----------------------------------------+----+
| Record plaintext buffer | | PL |
+----------------------------------------+----+
\__ PL __/
+------------------------------------...
| read for padding check ...
+------------------------------------...
|
contents discarded
from here
1.b) Claimed padding length > plaintext length
+----------------------------------------+----+
| Record plaintext buffer | PL |
+----------------------------------------+----+
+-------------------------...
| read for padding check ...
+-------------------------...
|
contents discarded
from here
2) New CBC padding check
+----------------------------------------+----+
| Record plaintext buffer | | PL |
+----------------------------------------+----+
\__ PL __/
+---------------------------------------+
| read for padding check |
+---------------------------------------+
|
contents discarded
until here
The previous version of the record encryption function
`ssl_encrypt_buf` takes the entire SSL context as an argument,
while intuitively, it should only depend on the current security
parameters and the record buffer.
Analyzing the exact dependencies, it turned out that in addition
to the currently active `ssl_transform` instance and the record
information, the encryption function needs access to
- the negotiated protocol version, and
- the status of the encrypt-then-MAC extension.
This commit moves these two fields into `ssl_transform` and
changes the signature of `ssl_encrypt_buf` to only use an instance
of `ssl_transform` and an instance of the new `ssl_record` type.
The `ssl_context` instance is *solely* kept for the debugging macros
which need an SSL context instance.
The benefit of the change is twofold:
1) It avoids the need of the MPS to deal with instances of
`ssl_context`. The MPS should only work with records and
opaque security parameters, which is what the change in
this commit makes progress towards.
2) It significantly eases testing of the encryption function:
independent of any SSL context, the encryption function can
be passed some record buffer to encrypt alongside some arbitrary
choice of parameters, and e.g. be checked to not overflow the
provided memory.
The macro constant `MBEDTLS_SSL_MAC_ADD` defined in `ssl_internal.h`
defines an upper bound for the amount of space needed for the record
authentication tag. Its definition distinguishes between the
presence of an ARC4 or CBC ciphersuite suite, in which case the maximum
size of an enabled SHA digest is used; otherwise, `MBEDTLS_SSL_MAC_ADD`
is set to 16 to accomodate AEAD authentication tags.
This assignment has a flaw in the situation where confidentiality is
not needed and the NULL cipher is in use. In this case, the
authentication tag also uses a SHA digest, but the definition of
`MBEDTLS_SSL_MAC_ADD` doesn't guarantee enough space.
The present commit fixes this by distinguishing between the presence
of *some* ciphersuite using a MAC, including those using a NULL cipher.
For that, the previously internal macro `SSL_SOME_MODES_USE_MAC` from
`ssl_tls.c` is renamed and moved to the public macro
`MBEDTLS_SOME_MODES_USE_MAC` defined in `ssl_internal.h`.
