There are two options:
1. Don't set it, and don't use it during record protection,
guarding the respective paths by a check whether TLS or
DTLS is used.
2. Set it to the default value even for TLS, and avoid the
protocol-dependent branch during record protection.
This commit picks option 2.
This commit changes the stack's behaviour when facing a record
with a non-matching CID. Previously, the stack failed in this
case, while now we silently skip over the current record.
Previously, ssl_get_next_record() would fetch 13 Bytes for the
record header and hand over to ssl_parse_record_header() to parse
and validate these. With the introduction of CID-based records, the
record length is not known in advance, and parsing and validating
must happen at the same time. ssl_parse_record_header() is therefore
rewritten in the following way:
1. Fetch and validate record content type and version.
2. If the record content type indicates a record including a CID,
adjust the record header pointers accordingly; here, we use the
statically configured length of incoming CIDs, avoiding any
elaborate CID parsing mechanism or dependency on the record
epoch, as explained in the previous commit.
3. Fetch the rest of the record header (note: this doesn't actually
fetch anything, but makes sure that the datagram fetched in the
earlier call to ssl_fetch_input() contains enough data).
4. Parse and validate the rest of the record header as before.
This commit modifies the code surrounding the invocations of
ssl_decrypt_buf() and ssl_encrypt_buf() to deal with a change
of record content type during CID-based record encryption/decryption.
mbedtls_ssl_context contains pointers in_buf, in_hdr, in_len, ...
which point to various parts of the header of an incoming TLS or
DTLS record; similarly, there are pointers out_buf, ... for
outgoing records.
This commit adds fields in_cid and out_cid which point to where
the CID of incoming/outgoing records should reside, if present,
namely prior to where the record length resides.
Quoting https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-04:
The DTLSInnerPlaintext value is then encrypted and the CID added to
produce the final DTLSCiphertext.
struct {
ContentType special_type = tls12_cid; /* 25 */
ProtocolVersion version;
uint16 epoch;
uint48 sequence_number;
opaque cid[cid_length]; // New field
uint16 length;
opaque enc_content[DTLSCiphertext.length];
} DTLSCiphertext;
For outgoing records, out_cid is set in ssl_update_out_pointers()
based on the settings in the current outgoing transform.
For incoming records, ssl_update_in_pointers() sets in_cid as if no
CID was present, and it is the responsibility of ssl_parse_record_header()
to update the field (as well as in_len, in_msg and in_iv) when parsing
records that do contain a CID. This will be done in a subsequent commit.
Finally, the code around the invocations of ssl_decrypt_buf()
and ssl_encrypt_buf() is adapted to transfer the CID from the
input/output buffer to the CID field in the internal record
structure (which is what ssl_{encrypt/decrypt}_buf() uses).
Note that mbedtls_ssl_in_hdr_len() doesn't need change because
it infers the header length as in_iv - in_hdr, which will account
for the CID for records using such.
Using the Connection ID extension increases the maximum record expansion
because
- the real record content type is added to the plaintext
- the plaintext may be padded with an arbitrary number of
zero bytes, in order to prevent leakage of information
through package length analysis. Currently, we always
pad the plaintext in a minimal way so that its length
is a multiple of 16 Bytes.
This commit adapts the various parts of the library to account
for that additional source of record expansion.
Context:
The CID draft does not require that the length of CIDs used for incoming
records must not change in the course of a connection. Since the record
header does not contain a length field for the CID, this means that if
CIDs of varying lengths are used, the CID length must be inferred from
other aspects of the record header (such as the epoch) and/or by means
outside of the protocol, e.g. by coding its length in the CID itself.
Inferring the CID length from the record's epoch is theoretically possible
in DTLS 1.2, but it requires the information about the epoch to be present
even if the epoch is no longer used: That's because one should silently drop
records from old epochs, but not the entire datagrams to which they belong
(there might be entire flights in a single datagram, including a change of
epoch); however, in order to do so, one needs to parse the record's content
length, the position of which is only known once the CID length for the epoch
is known. In conclusion, it puts a significant burden on the implementation
to infer the CID length from the record epoch, which moreover mangles record
processing with the high-level logic of the protocol (determining which epochs
are in use in which flights, when they are changed, etc. -- this would normally
determine when we drop epochs).
Moreover, with DTLS 1.3, CIDs are no longer uniquely associated to epochs,
but every epoch may use a set of CIDs of varying lengths -- in that case,
it's even theoretically impossible to do record header parsing based on
the epoch configuration only.
We must therefore seek a way for standalone record header parsing, which
means that we must either (a) fix the CID lengths for incoming records,
or (b) allow the application-code to configure a callback to implement
an application-specific CID parsing which would somehow infer the length
of the CID from the CID itself.
Supporting multiple lengths for incoming CIDs significantly increases
complexity while, on the other hand, the restriction to a fixed CID length
for incoming CIDs (which the application controls - in contrast to the
lengths of the CIDs used when writing messages to the peer) doesn't
appear to severely limit the usefulness of the CID extension.
Therefore, the initial implementation of the CID feature will require
a fixed length for incoming CIDs, which is what this commit enforces,
in the following way:
In order to avoid a change of API in case support for variable lengths
CIDs shall be added at some point, we keep mbedtls_ssl_set_cid(), which
includes a CID length parameter, but add a new API mbedtls_ssl_conf_cid_len()
which applies to an SSL configuration, and which fixes the CID length that
any call to mbetls_ssl_set_cid() which applies to an SSL context that is bound
to the given SSL configuration must use.
While this creates a slight redundancy of parameters, it allows to
potentially add an API like mbedtls_ssl_conf_cid_len_cb() later which
could allow users to register a callback which dynamically infers the
length of a CID at record header parsing time, without changing the
rest of the API.
The function mbedtls_ssl_hdr_len() returns the length of the record
header (so far: always 13 Bytes for DTLS, and always 5 Bytes for TLS).
With the introduction of the CID extension, the lengths of record
headers depends on whether the records are incoming or outgoing,
and also on the current transform.
Preparing for this, this commit splits mbedtls_ssl_hdr_len() in two
-- so far unmodified -- functions mbedtls_ssl_in_hdr_len() and
mbedtls_ssl_out_hdr_len() and replaces the uses of mbedtls_ssl_hdr_len()
according to whether they are about incoming or outgoing records.
There is no need to change the signature of mbedtls_ssl_{in/out}_hdr_len()
in preparation for its dependency on the currently active transform,
since the SSL context is passed as an argument, and the currently
active transform is referenced from that.
With the introduction of the CID feature, the stack needs to be able
to handle a change of record content type during record protection,
which in particular means that the record content type check will
need to move or be duplicated.
This commit introduces a tiny static helper function which checks
the validity of record content types, which hopefully makes it
easier to subsequently move or duplicate this check.
With the introduction of the CID extension, the record content type
may change during decryption; we must therefore re-consider every
record content type check that happens before decryption, and either
move or duplicate it to ensure it also applies to records whose
real content type is only revealed during decryption.
This commit does this for the silent dropping of unexpected
ApplicationData records in DTLS. Previously, this was caught
in ssl_parse_record_header(), returning
MBEDTLS_ERR_SSL_UNEXPECTED_RECORD which in ssl_get_next_record()
would lead to silent skipping of the record.
When using CID, this check wouldn't trigger e.g. when delayed
encrypted ApplicationData records come on a CID-based connection
during a renegotiation.
This commit moves the check to mbedtls_ssl_handle_message_type()
and returns MBEDTLS_ERR_SSL_NON_FATAL if it triggers, which leads
so silent skipover in the caller mbedtls_ssl_read_record().
The SSL context structure mbedtls_ssl_context contains several pointers
ssl->in_hdr, ssl->in_len, ssl->in_iv, ssl->in_msg pointing to various
parts of the record header in an incoming record, and they are setup
in the static function ssl_update_in_pointers() based on the _expected_
transform for the next incoming record.
In particular, the pointer ssl->in_msg is set to where the record plaintext
should reside after record decryption, and an assertion double-checks this
after each call to ssl_decrypt_buf().
This commit removes the dependency of ssl_update_in_pointers() on the
expected incoming transform by setting ssl->in_msg to ssl->in_iv --
the beginning of the record content (potentially including the IV) --
and adjusting ssl->in_msg after calling ssl_decrypt_buf() on a protected
record.
Care has to be taken to not load ssl->in_msg before calling
mbedtls_ssl_read_record(), then, which was previously the
case in ssl_parse_server_hello(); the commit fixes that.
If a record exhibits an invalid feature only after successful
authenticated decryption, this is a protocol violation by the
peer and should hence lead to connection failure. The previous
code, however, would silently ignore such records. This commit
fixes this.
So far, the only case to which this applies is the non-acceptance
of empty non-AD records in TLS 1.2. With the present commit, such
records lead to connection failure, while previously, they were
silently ignored.
With the introduction of the Connection ID extension (or TLS 1.3),
this will also apply to records whose real content type -- which
is only revealed during authenticated decryption -- is invalid.
In contrast to other aspects of the Connection ID extension,
the CID-based additional data for MAC computations differs from
the non-CID case even if the CID length is 0, because it
includes the CID length.
Quoting the CID draft 04:
- Block Ciphers:
MAC(MAC_write_key, seq_num +
tls12_cid + // New input
DTLSPlaintext.version +
cid + // New input
cid_length + // New input
length_of_DTLSInnerPlaintext + // New input
DTLSInnerPlaintext.content + // New input
DTLSInnerPlaintext.real_type + // New input
DTLSInnerPlaintext.zeros // New input
)
And similar for AEAD and Encrypt-then-MAC.
This commit temporarily comments the copying of the negotiated CIDs
into the established ::mbedtls_ssl_transform in mbedtls_ssl_derive_keys()
until the CID feature has been fully implemented.
While mbedtls_ssl_decrypt_buf() and mbedtls_ssl_encrypt_buf() do
support CID-based record protection by now and can be unit tested,
the following two changes in the rest of the stack are still missing
before CID-based record protection can be integrated:
- Parsing of CIDs in incoming records.
- Allowing the new CID record content type for incoming records.
- Dealing with a change of record content type during record
decryption.
Further, since mbedtls_ssl_get_peer_cid() judges the use of CIDs by
the CID fields in the currently transforms, this change also requires
temporarily disabling some grepping for ssl_client2 / ssl_server2
debug output in ssl-opt.sh.
This commit modifies ssl_decrypt_buf() and ssl_encrypt_buf()
to include the CID into authentication data during record
protection.
It does not yet implement the new DTLSInnerPlaintext format
from https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-04
* 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.
This commit rewrites mbedtls_x509write_crt_pem() to not use
a statically size stack buffer to temporarily store the DER
encoded form of the certificate to be written.
This is not necessary because the DER-to-PEM conversion
accepts overlapping input and output buffers.
The CRT writing routine mbedtls_x509write_crt_der() prepares the TBS
(to-be-signed) part of the CRT in a temporary stack-allocated buffer,
copying it to the actual output buffer at the end of the routine.
This comes at the cost of a very large stack buffer. Moreover, its size
must be hardcoded to an upper bound for the lengths of all CRTs to be
written through the routine. So far, this upper bound was set to 2Kb, which
isn't sufficient some larger certificates, as was reported e.g. in #2631.
This commit fixes this by changing mbedtls_x509write_crt_der() to write
the certificate in-place in the output buffer, thereby avoiding the use
of a statically sized stack buffer for the TBS.
Fixes#2631.
* 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`.
Prior to this commit, the security parameter struct `ssl_transform`
contained a `ciphersuite_info` field pointing to the information
structure for the negotiated ciphersuite. However, the only
information extracted from that structure that was used in the core
encryption and decryption functions `ssl_encrypt_buf`/`ssl_decrypt_buf`
was the authentication tag length in case of an AEAD cipher.
The present commit removes the `ciphersuite_info` field from the
`ssl_transform` structure and adds an explicit `taglen` field
for AEAD authentication tag length.
This is in accordance with the principle that the `ssl_transform`
structure should contain the raw parameters needed for the record
encryption and decryption functions to work, but not the higher-level
information that gave rise to them. For example, the `ssl_transform`
structure implicitly contains the encryption/decryption keys within
their cipher contexts, but it doesn't contain the SSL master or
premaster secrets. Likewise, it contains an explicit `maclen`, while
the status of the 'Truncated HMAC' extension -- which determines the
value of `maclen` when the `ssl_transform` structure is created in
`ssl_derive_keys` -- is not contained in `ssl_transform`.
The `ciphersuite_info` pointer was used in other places outside
the encryption/decryption functions during the handshake, and for
these functions to work, this commit adds a `ciphersuite_info` pointer
field to the handshake-local `ssl_handshake_params` structure.
The `ssl_transform` security parameter structure contains opaque
cipher contexts for use by the record encryption/decryption functions
`ssl_decrypt_buf`/`ssl_encrypt_buf`, while the underlying key material
is configured once in `ssl_derive_keys` and is not explicitly dealt with
anymore afterwards. In particular, the key length is not needed
explicitly by the encryption/decryption functions but is nonetheless
stored in an explicit yet superfluous `keylen` field in `ssl_transform`.
This commit removes this field.
Resolve conflicts by performing the following:
- Ensure calls to mbedtls_x509_crt_verify_* are made with callbacks
* origin/pr/2539:
Make CRT callback tests more robust
Rename constant in client2.c
Fix typo
Add test for configuration specific CRT callback
Fix doxygen documentation of mbedtls_ssl_set_verify()
Add test exercising context-specific CRT callback to ssl-opt.sh
Add cmd to use context-specific CRT callback in ssl_client2
Implement context-specific verification callbacks
Add context-specific CRT verification callbacks
Improve documentation of mbedtls_ssl_conf_verify()
* origin/pr/2532: (29 commits)
Document and test flags in x509_verify
Fix style issues and a typo
Fix name to function call
Address comments for x509 tests
Address review comments regarding ssl_client2 and ssl tests
Remove mbedtls_ from the static function name
Change docs according to review comments
Change the verify function naming
Fix ssl_client2 and ssl_server2 if !PLATFORM_C
Correct placement of usage macro in ssl_client2
Update version_features.c
Remove trailing whitespace in test_suite_x509parse.function
Update query_config.c
Add ssl-opt.sh tests for trusted CA callbacks
Only run X.509 CRT verification tests with CA callback tests if !CRL
Minor fixes to CA callback tests
Declare CA callback type even if feature is disabled
Implement X.509 CRT verification using CA callback
Add prototype for CRT verification with static and dynamic CA list
Make use of CA callback if present when verifying peer CRT chain
...
So far, there were the following CRT verification functions:
- `mbedtls_x509_crt_verify()` -- no profile, no restartable ECC
- `mbedtls_x509_crt_verify_with_profile()` -- profile, no restartable ECC
- `mbedtls_x509_crt_verify_restartable()` -- profile, restartable ECC
all publicly declared and offering increasing functionality.
On the implementation-side,
- `mbedtls_x509_crt_verify()` resolves to
a call to `mbedtls_x509_crt_verify_with_profile()` setting
the profile to `NULL`, and
- `mbedtls_x509_crt_verify_with_profile()`
resolves to a call to ``mbedtls_x509_crt_verify_restartable()`
setting the ECC restart context to NULL.
This commit adds two more functions to this zoo:
- `mbedtls_x509_crt_verify_with_cb()`
- `x509_crt_verify_restartable_cb()`
Here, `mbedtls_x509_crt_verify_with_cb()` is similar to
`mbedtls_x509_crt_verify_with_profile()` but uses a CA callback
instead of a static CA list, and no restart context.
`x509_crt_verify_restartable_cb()` is similar to
`mbedtls_x509_crt_verify_restartable()` but allows to either use
a static list of trusted CAs _or_ a trusted CA callback.
On the implementation-side,
- the body of `mbedtls_x509_crt_verify_restartable()` is moved to
`x509_crt_verify_restartable_cb()`, and the new version of
`mbedtls_x509_crt_verify_restartable()` just resolves to
`x509_crt_verify_restartable_cb()` with the trusted CA callback
set to NULL.
- The new function `mbedtls_x509_crt_verify_with_cb()`
forward to `x509_crt_verify_restartable_cb()` with the restart
context set to `NULL`.
There's no change to the implementation yet, and in particular,
`mbedtls_x509_crt_verify_with_cb()` isn't yet usable.
* restricted/pr/551:
ECP: Clarify test descriptions
ECP: remove extra whitespaces
Fix ECDH secret export for Mongomery curves
Improve ECP test names
Make ecp_get_type public
Add more tests for ecp_read_key
ECP: Catch unsupported import/export
Improve documentation of mbedtls_ecp_read_key
Fix typo in ECP module
Remove unnecessary cast from ECP test
Improve mbedtls_ecp_point_read_binary tests
Add Montgomery points to ecp_point_write_binary
ECDH: Add test vectors for Curve25519
Add little endian export to Bignum
Add mbedtls_ecp_read_key
Add Montgomery points to ecp_point_read_binary
Add little endian import to Bignum
Ensure this merge passes tests by auto-generating query_config.c, adding
MBEDTLS_ECDH_LEGACY_CONTEXT to it.
* restricted/pr/552:
Fix mbedtls_ecdh_get_params with new ECDH context
Test undefining MBEDTLS_ECDH_LEGACY_CONTEXT in all.sh
Define MBEDTLS_ECDH_LEGACY_CONTEXT in config.h
Add changelog entry for mbedtls_ecdh_get_params robustness
Fix ecdh_get_params with mismatching group
Add test case for ecdh_get_params with mismatching group
Add test case for ecdh_calc_secret
Fix typo in documentation
Ensure tests pass when the submodule is used by updating the list of
crypto tests to include test_suite_oid in both tests/CMakeLists.txt and
tests/Makefile.
* origin/pr/2531:
Add changeLog entry
Add certificate policy of type any policy id
* origin/pr/2509:
all.sh: Generate seedfile for crypto submodule tests
Update crypto submodule to test with private headers
tests: Use globbing in test suite exclusion list
Update crypto submodule to Mbed Crypto development
tests: Test crypto via the crypto submodule
Update the crypto submodule to the top of the Mbed Crypto development
branch. This brings in a version of Mbed Crypto that enables building
Mbed Crypto tests that depend on private headers, like
'psa_crypto_invasive.h'.
This also requires updating our config.h to include new configuration
options added to Mbed Crypto. MBEDTLS_PSA_ITS_FILE_C replaces
MBEDTLS_PSA_CRYPTO_STORAGE_FILE_C and MBEDTLS_PSA_CRYPTO_STORAGE_ITS_C.
MBEDTLS_PSA_INJECT_ENTROPY replaces MBEDTLS_PSA_HAS_ITS_IO.
* origin/pr/1520:
Use certificates from data_files and refer them
Specify server certificate to use in SHA-1 test
refactor CA and SRV certificates into separate blocks
refactor SHA-1 certificate defintions and assignment
refactor server SHA-1 certificate definition into a new block
define TEST_SRV_CRT_RSA_SOME in similar logic to TEST_CA_CRT_RSA_SOME
server SHA-256 certificate now follows the same logic as CA SHA-256 certificate
add entry to ChangeLog
* public/pr/2421: (68 commits)
Fix unused variable warning in ssl_parse_certificate_coordinate()
Add missing compile time guard in ssl_client2
Update programs/ssl/query_config.c
ssl_client2: Reset peer CRT info string on reconnect
Add further debug statements on assertion failures
Fix typo in documentation of ssl_parse_certificate_chain()
Add debug output in case of assertion failure
Fix typo in SSL ticket documentation
Add config sanity check for !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE
ssl_client2: Zeroize peer CRT info buffer when reconnecting
Reintroduce numerous ssl-opt.sh tests if !MBEDTLS_SSL_KEEP_PEER_CERT
ssl_client2: Extract peer CRT info from verification callback
Improve documentation of mbedtls_ssl_get_peer_cert()
Improve documentation of MBEDTLS_SSL_KEEP_PEER_CERTIFICATE
Fix indentation of Doxygen comment in ssl_internal.h
Set peer CRT length only after successful allocation
Remove question in comment about verify flags on cli vs. server
Remove misleading and redundant guard around restartable ECC field
Add test for !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE to all.sh
Free peer CRT chain immediately after verifying it
...
* restricted/pr/528:
Update query_config.c
Fix failure in SSLv3 per-version suites test
Adjust DES exclude lists in test scripts
Clarify 3DES changes in ChangeLog
Fix documentation for 3DES removal
Exclude 3DES tests in test scripts
Fix wording of ChangeLog and 3DES_REMOVE docs
Reduce priority of 3DES ciphersuites
* public/pr/2028:
Update the crypto submodule to a78c958
Fix ChangeLog entry to correct release version
Fix typo in x509write test data
Add ChangeLog entry for unused bits in bitstrings
Improve docs for named bitstrings and their usage
Add tests for (named) bitstring to suite_asn1write
Add new function mbedtls_asn1_write_named_bitstring()
Add a new function mbedtls_asn1_write_named_bitstring() that removes
trailing 0s at the end of DER encoded bitstrings. The function is
implemented according to Hanno Becker's suggestions.
This commit also changes the functions x509write_crt_set_ns_cert_type
and crt_set_key_usage to call the new function as the use named
bitstrings instead of the regular bitstrings.
The ecp_get_type function comes handy in higher level modules and tests
as well. It is not inline anymore, to enable alternative implementations
to implement it for themselves.
mbedtls_ecp_read_key() module returned without an error even when
importing keys corresponding to the requested group was not
implemented.
We change this and return an error when the requested group is not
supported and make the remaining import/export functions more robust.
If we don't need to store the peer's CRT chain permanently, we may
free it immediately after verifying it. Moreover, since we parse the
CRT chain in-place from the input buffer in this case, pointers from
the CRT structure remain valid after freeing the structure, and we
use that to extract the digest and pubkey from the CRT after freeing
the structure.
It is used in `mbedtls_ssl_session_free()` under
`MBEDTLS_X509_CRT_PARSE_C`, but defined only if
`MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED`.
Issue #2422 tracks the use of
`MBEDTLS_KEY_EXCHANGE__WITH_CERT_ENABLED` instead of
`MBEDTLS_X509_CRT_PARSE_C` for code and fields
related to CRT-based ciphersuites.
The server expects a CertificateVerify message only if it has
previously received a Certificate from the client.
So far, this was detected by looking at the `peer_cert` field
in the current session. Preparing to remove the latter, this
commit changes this to instead determine the presence of a peer
certificate by checking the new `peer_cert_digest` pointer.
We must dispatch between the peer's public key stored as part of
the peer's CRT in the current session structure (situation until
now, and future behaviour if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is
enabled), and the sole public key stored in the handshake structure
(new, if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is disabled).
We must dispatch between the peer's public key stored as part of
the peer's CRT in the current session structure (situation until
now, and future behaviour if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is
enabled), and the sole public key stored in the handshake structure
(new, if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is disabled).
We must dispatch between the peer's public key stored as part of
the peer's CRT in the current session structure (situation until
now, and future behaviour if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is
enabled), and the sole public key stored in the handshake structure
(new, if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is disabled).
We must dispatch between the peer's public key stored as part of
the peer's CRT in the current session structure (situation until
now, and future behaviour if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is
enabled), and the sole public key stored in the handshake structure
(new, if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is disabled).
This commit modifies `mbedtls_ssl_parse_certificate()` to store a
copy of the peer's public key after parsing and verifying the peer's
CRT chain.
So far, this leads to heavy memory duplication: We have the CRT chain
in the I/O buffer, then parse (and, thereby, copy) it to a
`mbedtls_x509_crt` structure, and then make another copy of the
peer's public key, plus the overhead from the MPI and ECP structures.
This inefficiency will soon go away to a significant extend, because:
- Another PR adds functionality to parse CRTs without taking
ownership of the input buffers. Applying this here will allow
parsing and verifying the peer's chain without making an additional
raw copy. The overhead reduces to the size of `mbedtls_x509_crt`,
the public key, and the DN structures referenced in the CRT.
- Once copyless parsing is in place and the removal of the peer CRT
is fully implemented, we can extract the public key bounds from
the parsed certificate and then free the entire chain before
parsing the public key again. This means that we never store
the parsed public key twice at the same time.
When removing the (session-local) copy of the peer's CRT chain, we must
keep a handshake-local copy of the peer's public key, as (naturally) every
key exchange will make use of that public key at some point to verify that
the peer actually owns the corresponding private key (e.g., verify signatures
from ServerKeyExchange or CertificateVerify, or encrypt a PMS in a RSA-based
exchange, or extract static (EC)DH parameters).
This commit adds a PK context field `peer_pubkey` to the handshake parameter
structure `mbedtls_handshake_params_init()` and adapts the init and free
functions accordingly. It does not yet make actual use of the new field.
This commit adds an ASN.1 buffer field `pk_raw` to `mbedtls_x509_crt`
which stores the bounds of the raw public key data within an X.509 CRT.
This will be useful in subsequent commits to extract the peer's public
key from its certificate chain.
This commit changes the format of session tickets to include
the digest of the peer's CRT if MBEDTLS_SSL_KEEP_PEER_CERTIFICATE
is disabled.
This commit does not yet remove the peer CRT itself.
`mbedtls_ssl_parse_certificate()` parses the peer's certificate chain
directly into the `peer_cert` field of the `mbedtls_ssl_session`
structure being established. To allow to optionally remove this field
from the session structure, this commit changes this to parse the peer's
chain into a local variable instead first, which can then either be freed
after CRT verification - in case the chain should not be stored - or
mapped to the `peer_cert` if it should be kept. For now, only the latter
is implemented.
mbedtls_ssl_parse_certificate() will fail if a ciphersuite requires
a certificate, but none is provided. While it is sensible to double-
check this, failure should be reported as an internal error and not
as an unexpected message.
A subsequent commit will need this function in the session ticket
and session cache implementations. As the latter are server-side,
this commit also removes the MBEDTLS_SSL_CLI_C guard.
For now, the function is declared in ssl_internal.h and hence not
part of the public API.
This commit modifies the helper `ssl_parse_certificate_chain()` to
accep any target X.509 CRT chain instead of hardcoding it to
`session_negotiate->peer_cert`. This increases modularity and paves
the way towards removing `mbedtls_ssl_session::peer_cert`.
This commit simplifies the client-side code for outgoing CertificateVerify
messages, and server-side code for outgoing CertificateRequest messages and
incoming CertificateVerify messages, through the use of the macro
`MBEDTLS_KEY_EXCHANGE__CERT_REQ_ALLOWED__ENABLED`
indicating whether a ciphersuite allowing CertificateRequest messages
is enabled in the configuration, as well as the helper function
`mbedtls_ssl_ciphersuite_cert_req_allowed()`
indicating whether a particular ciphersuite allows CertificateRequest
messages.
These were already used in the client-side code to simplify the
parsing functions for CertificateRequest messages.
This commit adds a helper function `ssl_parse_certificate_coordinate()`
which checks whether a `Certificate` message is expected from the peer.
The logic is the following:
- For ciphersuites which don't use server-side CRTs, no Certificate
message is expected (neither for the server, nor the client).
- On the server, no client certificate is expected in the following cases:
* The server server didn't request a Certificate, which is controlled
by the `authmode` setting.
* A RSA-PSK suite is used; this is the only suite using server CRTs
but not allowing client-side authentication.
This commit introduces a static helper function
`mbedtls_ssl_ciphersuite_uses_srv_cert()`
which determines whether a ciphersuite may make use of server-side CRTs.
This function is in turn uses in `mbedtls_ssl_parse_certificate()` to
skip certificate parsing for ciphersuites which don't involve CRTs.
Note: Ciphersuites not using server-side CRTs don't allow client-side CRTs
either, so it is safe to guard `mbedtls_ssl_{parse/write}_certificate()`
this way.
Note: Previously, the code uses a positive check over the suites
- MBEDTLS_KEY_EXCHANGE_PSK
- MBEDTLS_KEY_EXCHANGE_DHE_PSK
- MBEDTLS_KEY_EXCHANGE_ECDHE_PSK
- MBEDTLS_KEY_EXCHANGE_ECJPAKE,
while now, it uses a negative check over `mbedtls_ssl_ciphersuite_uses_srv_cert()`,
which checks for the suites
- MBEDTLS_KEY_EXCHANGE_RSA
- MBEDTLS_KEY_EXCHANGE_RSA_PSK
- MBEDTLS_KEY_EXCHANGE_DHE_RSA
- MBEDTLS_KEY_EXCHANGE_ECDH_RSA
- MBEDTLS_KEY_EXCHANGE_ECDHE_RSA
- MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA
- MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA
This is equivalent since, together, those are all ciphersuites.
Quoting ssl_ciphersuites.h:
```
typedef enum {
MBEDTLS_KEY_EXCHANGE_NONE = 0,
MBEDTLS_KEY_EXCHANGE_RSA,
MBEDTLS_KEY_EXCHANGE_DHE_RSA,
MBEDTLS_KEY_EXCHANGE_ECDHE_RSA,
MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA,
MBEDTLS_KEY_EXCHANGE_PSK,
MBEDTLS_KEY_EXCHANGE_DHE_PSK,
MBEDTLS_KEY_EXCHANGE_RSA_PSK,
MBEDTLS_KEY_EXCHANGE_ECDHE_PSK,
MBEDTLS_KEY_EXCHANGE_ECDH_RSA,
MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA,
MBEDTLS_KEY_EXCHANGE_ECJPAKE,
} mbedtls_key_exchange_type_t;
```
The handler `mbedtls_ssl_parse_certificate()` for incoming `Certificate`
messages contains many branches updating the handshake state. For easier
reasoning about state evolution, this commit introduces a single code-path
updating the state machine at the end of `mbedtls_ssl_parse_certificate()`.
If an attempt for session resumption fails, the `session_negotiate` structure
might be partially filled, and in particular already contain a peer certificate
structure. This certificate structure needs to be freed before parsing the
certificate sent in the `Certificate` message.
This commit moves the code-path taking care of this from the helper
function `ssl_parse_certificate_chain()`, whose purpose should be parsing
only, to the top-level handler `mbedtls_ssl_parse_certificate()`.
The fact that we don't know the state of `ssl->session_negotiate` after
a failed attempt for session resumption is undesirable, and a separate
issue #2414 has been opened to improve on this.
This commit introduces a server-side static helper function
`ssl_srv_check_client_no_crt_notification()`, which checks if
the message we received during the incoming certificate state
notifies the server of the lack of certificate on the client.
For SSLv3, such a notification comes as a specific alert,
while for all other TLS versions, it comes as a `Certificate`
handshake message with an empty CRT list.
So far, we've used the `peer_cert` pointer to detect whether
we're parsing the first CRT, but that will soon be removed
if `MBEDTLS_SSL_KEEP_PEER_CERTIFICATE` is unset.
This commit introduces a helper function `ssl_clear_peer_cert()`
which frees all data related to the peer's certificate from an
`mbedtls_ssl_session` structure. Currently, this is the peer's
certificate itself, while eventually, it'll be its digest only.
After mitigating the 'triple handshake attack' by checking that
the peer's end-CRT didn't change during renegotation, the current
code avoids re-parsing the CRT by moving the CRT-pointer from the
old session to the new one. While efficient, this will no longer
work once only the hash of the peer's CRT is stored beyond the
handshake.
This commit removes the code-path moving the old CRT, and instead
frees the entire peer CRT chain from the initial handshake as soon
as the 'triple handshake attack' protection has completed.
Renamed the tests because they are explicitly testing Curve25519 and
nothing else. Improved test coverage, test documentation and extended
in-code documentation with a specific reference to the standard as well.
The library is able to perform computations and cryptographic schemes on
curves with x coordinate ladder representation. Here we add the
capability to export such points.
The function `mbedtls_mpi_write_binary()` writes big endian byte order,
but we need to be able to write little endian in some caseses. (For
example when handling keys corresponding to Montgomery curves.)
Used `echo xx | tac -rs ..` to transform the test data to little endian.
The private keys used in ECDH differ in the case of Weierstrass and
Montgomery curves. They have different constraints, the former is based
on big endian, the latter little endian byte order. The fundamental
approach is different too:
- Weierstrass keys have to be in the right interval, otherwise they are
rejected.
- Any byte array of the right size is a valid Montgomery key and it
needs to be masked before interpreting it as a number.
Historically it was sufficient to use mbedtls_mpi_read_binary() to read
private keys, but as a preparation to improve support for Montgomery
curves we add mbedtls_ecp_read_key() to enable uniform treatment of EC
keys.
For the masking the `mbedtls_mpi_set_bit()` function is used. This is
suboptimal but seems to provide the best trade-off at this time.
Alternatives considered:
- Making a copy of the input buffer (less efficient)
- removing the `const` constraint from the input buffer (breaks the api
and makes it less user friendly)
- applying the mask directly to the limbs (violates the api between the
modules and creates and unwanted dependency)
The library is able to perform computations and cryptographic schemes on
curves with x coordinate ladder representation. Here we add the
capability to import such points.
The function `mbedtls_mpi_read_binary()` expects big endian byte order,
but we need to be able to read from little endian in some caseses. (For
example when handling keys corresponding to Montgomery curves.)
Used `echo xx | tac -rs .. | tr [a-z] [A-Z]` to transform the test data
to little endian and `echo "ibase=16;xx" | bc` to convert to decimal.
Define MBEDTLS_ECDH_LEGACY_CONTEXT in config.h instead of hard-coding
this in ecdh.h so that its absence can be tested. Document it as
experimental so that we reserve the right to change it in the future.
If mbedtls_ecdh_get_params is called with keys belonging to
different groups, make it return an error the second time, rather than
silently interpret the first key as being on the second curve.
This makes the non-regression test added by the previous commit pass.
This commit improves hygiene and formatting of macro definitions
throughout the library. Specifically:
- It adds brackets around parameters to avoid unintended
interpretation of arguments, e.g. due to operator precedence.
- It adds uses of the `do { ... } while( 0 )` idiom for macros that
can be used as commands.
- Populate the ECDH private key slot with a fresh private EC key
designated for the correct algorithm.
- Export the public part of the ECDH private key from PSA and
reformat it to suite the format of the ClientKeyExchange message.
- Perform the PSA-based ECDH key agreement and store the result
as the premaster secret for the connection.
- Reformat the server's ECDH public key to make it suitable
for the PSA key agreement API. Currently, the key agreement
API needs a full SubjectPublicKeyInfo structure, while the
TLS ServerKeyExchange message only contains a ECPoint structure.
Enable handling of zero-length null output in PKCS1 v1.5 decryption.
Prevent undefined behavior by avoiding a memcpy() to zero-length null
output buffers.
In mbedtls_rsa_rsaes_oaep_encrypt and
mbedtls_rsa_rsaes_pkcs1_v15_encrypt, if the input length is 0 (which
is unusual and mostly useless, but permitted) then it is fine for the
input pointer to be NULL. Don't return an error in this case.
When `input` is NULL, `memcpy( p, input, ilen )` has undefined behavior
even if `ilen` is zero. So skip the `memcpy` call in this case.
Likewise, in `mbedtls_rsa_rsaes_oaep_decrypt`, skip the `memcpy` call if
`*olen` is zero.
Context: During a handshake, the SSL/TLS handshake logic constructs
an instance of ::mbedtls_ssl_session representing the SSL session
being established. This structure contains information such as the
session's master secret, the peer certificate, or the session ticket
issues by the server (if applicable).
During a renegotiation, the new session is constructed aside the existing
one and destroys and replaces the latter only when the renegotiation is
complete. While conceptually clear, this means that during the renegotiation,
large pieces of information such as the peer's CRT or the session ticket
exist twice in memory, even though the original versions are removed
eventually.
This commit removes the simultaneous presence of two peer CRT chains
in memory during renegotiation, in the following way:
- Unlike in the case of SessionTickets handled in the previous commit,
we cannot simply free the peer's CRT chain from the previous handshake
before parsing the new one, as we need to verify that the peer's end-CRT
hasn't changed to mitigate the 'Triple Handshake Attack'.
- Instead, we perform a binary comparison of the original peer end-CRT
with the one presented during renegotiation, and if it succeeds, we
avoid re-parsing CRT by moving the corresponding CRT pointer from the
old to the new session structure.
- The remaining CRTs in the peer's chain are not affected by the triple
handshake attack protection, and for them we may employ the canonical
approach of freeing them before parsing the remainder of the new chain.
Note that this commit intends to not change any observable behavior
of the stack. In particular:
- The peer's CRT chain is still verified during renegotiation.
- The tail of the peer's CRT chain may change during renegotiation.
Context: During a handshake, the SSL/TLS handshake logic constructs
an instance of ::mbedtls_ssl_session representing the SSL session
being established. This structure contains information such as the
session's master secret, the peer certificate, or the session ticket
issues by the server (if applicable).
During a renegotiation, the new session is constructed aside the existing
one and destroys and replaces the latter only when the renegotiation is
complete. While conceptually clear, this means that during the renegotiation,
large pieces of information such as the peer's CRT or the session ticket
exist twice in memory, even though the original versions are removed
eventually.
This commit starts removing this memory inefficiency by freeing the old
session's SessionTicket before the one for the new session is allocated.
Context:
The existing API `mbedtls_x509_parse_crt_der()` for parsing DER
encoded X.509 CRTs unconditionally makes creates a copy of the
input buffer in RAM. While this comes at the benefit of easy use,
-- specifically: allowing the user to free or re-use the input
buffer right after the call -- it creates a significant memory
overhead, as the CRT is duplicated in memory (at least temporarily).
This might not be tolerable a resource constrained device.
As a remedy, this commit adds a new X.509 API call
`mbedtls_x509_parse_crt_der_nocopy()`
which has the same signature as `mbedtls_x509_parse_crt_der()`
and almost the same semantics, with one difference: The input
buffer must persist and be unmodified for the lifetime of the
established instance of `mbedtls_x509_crt`, that is, until
`mbedtls_x509_crt_free()` is called.
Resolve incompatibilties in the RSA module where changes made for
parameter validation prevent Mbed Crypto from working. Mbed Crypto
depends on being able to pass zero-length buffers that are NULL to RSA
encryption functions.
This reverts commit 2f660d047d.
