This is the first step towards making verify_chain() iterative. While from a
readability point of view the current recursive version is fine, one of the
goals of this refactoring is to prepare for restartable ECC integration, which
will need the explicit stack anyway.
Besides avoiding near-duplication, this avoids having three generations of
certificate (child, parent, grandparent) in one function, with all the
off-by-one opportunities that come with it.
This also allows to simplify the signature of verify_child(), which will be
done in next commit.
This is from the morally 5th (and soon obsolete) invocation of this function
in verify_top().
Doing this badtime-skipping when we search for a parent in the provided chain
is a change of behaviour, but it's backwards-compatible: it can only cause us
to accept valid chains that we used to reject before. Eg if the peer has a
chain with two version of an intermediate certificate with different validity
periods, the first non valid and the second valid - such cases are probably
rare or users would have complained already, but it doesn't hurt to handle it
properly as it allows for more uniform code.
This may look like a behaviour change because one check has been added to the
function that was previously done in only one of the 3 call sites. However it
is not, because:
- for the 2 call sites in verify(), the test always succeeds as path_cnt is 0.
- for the call site in verify_child(), the same test was done later anyway in
verify_top()
There are 3 instance that were replaced, but 2 instances of variants of this
function exist and will be handled next (the extra parameter that isn't used
so far is in preparation for that):
- one in verify_child() where path_cnt constraint is handled too
- one in verify_top() where there is extra logic to skip parents that are
expired or future, but only if there are better parents to be found
This is a slight change of behaviour in that the previous condition was:
- same subject
- signature matches
while the new condition is:
- exact same certificate
However the documentation for mbedtls_x509_crt_verify() (note on trust_ca)
mentions the new condition, so code that respected the documentation will keep
working.
In addition, this is a bit faster as it doesn't check the self-signature
(which never needs to be checked for certs in the trusted list).
When we're looking for a parent, in trusted CAs, 'top' should be 1.
This only impacted which call site for verify_top() was chosen, and the error
was then fixed inside verify_top() by iterating over CAs again, this time
correctly setting 'top' to 1.
This is the beginning of a series of commits refactoring the chain
building/verification functions in order to:
- make it simpler to understand and work with
- prepare integration of restartable ECC
md() already checks for md_info == NULL. Also, in the future it might also
return other errors (eg hardware errors if acceleration is used), so it make
more sense to check its return value than to check for NULL ourselves and then
assume no other error can occur.
Also, currently, md_info == NULL can never happen except if the MD and OID modules
get out of sync, or if the user messes with members of the x509_crt structure
directly.
This commit does not change the current behaviour, which is to treat MD errors
the same way as a bad signature or no trusted root.
Modify the function mbedtls_x509_csr_parse_der() so that it checks the
parsed CSR version integer before it increments the value. This prevents
a potential signed integer overflow, as these have undefined behaviour
in the C standard.
Rename the macro MBEDTLS_PLATFORM_SETUP_ALT to
MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT to make the name more descriptive
as this macro enables/disables both functions.
Add the following two functions to allow platform setup and teardown
operations for the full library to be hooked in:
* mbedtls_platform_setup()
* mbedtls_platform_teardown()
An mbedtls_platform_context C structure is also added and two internal
functions that are called by the corresponding setup and teardown
functions above:
* mbedtls_internal_platform_setup()
* mbedtls_internal_plartform_teardown()
Finally, the macro MBEDTLS_PLATFORM_SETUP_ALT is also added to allow
mbedtls_platform_context and internal function to be overriden by the
user as needed for a platform.
The previous commit bd5ceee484f201b90a384636ba12de86bd330cba removed
the definition of the global constants
- mbedtls_test_ca_crt_rsa_len,
- mbedtls_test_cli_crt_rsa_len,
- mbedtls_test_ca_crt_rsa, and
- mbedtls_test_cli_crt_rsa.
This commit restores these to maintain ABI compatibility.
Further, it was noticed that without SHA256_C being enabled the
previous code failed to compile because because the SHA1 resp. SHA256
certificates were only defined when the respective SHAXXX_C options
were set, but the emission of the global variable mbedtls_test_ca_crt
was unconditionally defined through the SHA256
certificate. Previously, the RSA SHA1 certificate was unconditionally
defined and used for that.
As a remedy, this commit makes sure some RSA certificate is defined
and exported through the following rule:
1. If SHA256_C is active, define an RSA SHA256 certificate and export
it as mbedtls_test_ca_crt. Also, define SHA1 certificates only if
SHA1_C is set.
2. If SHA256_C is not set, always define SHA1 certificate and export
it as mbedtls_test_ca_crt.
Fix a resource leak on windows platform, in mbedtls_x509_crt_parse_path,
in case a failure. when an error occurs, goto cleanup, and free the
resource, instead of returning error code immediately.
Protecting the ECP hardware acceleratior with mutexes is inconsistent with the
philosophy of the library. Pre-existing hardware accelerator interfaces
leave concurrency support to the underlying platform.
Fixes#863
If we didn't walk the whole chain, then there may be any kind of errors in the
part of the chain we didn't check, so setting all flags looks like the safe
thing to do.
* restricted/iotssl-1398:
Add ChangeLog entry
Ensure application data records are not kept when fully processed
Add hard assertion to mbedtls_ssl_read_record_layer
Fix mbedtls_ssl_read
Simplify retaining of messages for future processing
This commit fixes the following case: If a client is both expecting a
SERVER_HELLO and has an application data record that's partially
processed in flight (that's the situation the client gets into after
receiving a ServerHelloRequest followed by ApplicationData), a
subsequent call to mbedtls_ssl_read will set keep_current_message = 1
when seeing the unexpected application data, but not reset it to 0
after the application data has been processed. This commit fixes this.
It also documents and suggests how the problem might be solved in a
more structural way on the long run.
This commit adds a hard assertion to mbedtls_ssl_read_record_layer
triggering if both ssl->in_hslen and ssl->in_offt are not 0. This
should never happen, and if it does, there's no sensible way of
telling whether the previous message was a handshake or an application
data message.
There are situations in which it is not clear what message to expect
next. For example, the message following the ServerHello might be
either a Certificate, a ServerKeyExchange or a CertificateRequest. We
deal with this situation in the following way: Initially, the message
processing function for one of the allowed message types is called,
which fetches and decodes a new message. If that message is not the
expected one, the function returns successfully (instead of throwing
an error as usual for unexpected messages), and the handshake
continues to the processing function for the next possible message. To
not have this function fetch a new message, a flag in the SSL context
structure is used to indicate that the last message was retained for
further processing, and if that's set, the following processing
function will not fetch a new record.
This commit simplifies the usage of this message-retaining parameter
by doing the check within the record-fetching routine instead of the
specific message-processing routines. The code gets cleaner this way
and allows retaining messages to be used in other situations as well
without much effort. This will be used in the next commits.
This commit adds four tests to tests/ssl-opt.sh:
(1) & (2): Check behaviour of optional/required verification when the
trusted CA chain is empty.
(3) & (4): Check behaviour of optional/required verification when the
client receives a server certificate with an unsupported curve.
This commit changes the behaviour of mbedtls_ssl_parse_certificate
to make the two authentication modes MBEDTLS_SSL_VERIFY_REQUIRED and
MBEDTLS_SSL_VERIFY_OPTIONAL be in the following relationship:
Mode == MBEDTLS_SSL_VERIFY_REQUIRED
<=> Mode == MBEDTLS_SSL_VERIFY_OPTIONAL + check verify result
Also, it changes the behaviour to perform the certificate chain
verification even if the trusted CA chain is empty. Previously, the
function failed in this case, even when using optional verification,
which was brought up in #864.
* gilles/IOTSSL-1330/development:
Changelog entry for the bug fixes
SSLv3: when refusing renegotiation, stop processing
Ignore failures when sending fatal alerts
Cleaned up double variable declaration
Code portability fix
Added changelog entry
Send TLS alerts in many more cases
Skip all non-executables in run-test-suites.pl
SSL tests: server requires auth, client has no certificate
Balanced braces across preprocessor conditionals
Support setting the ports on the command line
By default, keep allowing SHA-1 in key exchange signatures. Disabling
it causes compatibility issues, especially with clients that use
TLS1.2 but don't send the signature_algorithms extension.
SHA-1 is forbidden in certificates by default, since it's vulnerable
to offline collision-based attacks.
In the TLS test client, allow SHA-1 as a signature hash algorithm.
Without this, the renegotation tests failed.
A previous commit had allowed SHA-1 via the certificate profile but
that only applied before the initial negotiation which includes the
signature_algorithms extension.
Default to forbidding the use of SHA-1 in TLS where it is unsafe: for
certificate signing, and as the signature hash algorithm for the TLS
1.2 handshake signature. SHA-1 remains allowed in HMAC-SHA-1 in the
XXX_SHA ciphersuites and in the PRF for TLS <= 1.1.
For easy backward compatibility for use in controlled environments,
turn on the MBEDTLS_TLS_DEFAULT_ALLOW_SHA1 compiled-time option.
* hanno/sig_hash_compatibility:
Improve documentation
Split long lines
Remember suitable hash function for any signature algorithm.
Introduce macros and functions to characterize certain ciphersuites.
Fixed a bug in ssl_srv.c when parsing TLS_FALLBACK_SCSV in the
ciphersuite list that caused it to miss it sometimes. Reported by Hugo
Leisink as issue #810. Fix initially by @andreasag01; this commit
isolates the bug fix and adds a non-regression test.
This patch modifies the following 2 functions in the AES module to
change the return type from void to int:
* mbedtls_aes_encrypt() -> mbedtls_internal_aes_encrypt()
* mbedtls_aes_decrypt() -> mbedtls_internal_aes_decrypt()
This change is necessary to allow users of MBEDTLS_AES_ALT,
MBEDTLS_AES_DECRYPT_ALT and MBEDTLS_AES_ENCRYPT_ALT to return an error
code when replacing the default with their own implementation, e.g.
a hardware crypto accelerator.
The RSA private key functions rsa_rsaes_pkcs1_v15_decrypt and
rsa_rsaes_oaep_decrypt put sensitive data (decryption results) on the
stack. Wipe it before returning.
Thanks to Laurent Simon for reporting this issue.
The sliding window exponentiation algorithm is vulnerable to
side-channel attacks. As a countermeasure we add exponent blinding in
order to prevent combining the results of different measurements.
This commit handles the case when the Chinese Remainder Theorem is used
to accelerate the computation.
The sliding window exponentiation algorithm is vulnerable to
side-channel attacks. As a countermeasure we add exponent blinding in
order to prevent combining the results of fifferent measurements.
This commits handles the case when the Chinese Remainder Theorem is NOT
used to accelerate computations.
According to RFC5246 the server can indicate the known Certificate
Authorities or can constrain the aurhorisation space by sending a
certificate list. This part of the message is optional and if omitted,
the client may send any certificate in the response.
The previous behaviour of mbed TLS was to always send the name of all the
CAs that are configured as root CAs. In certain cases this might cause
usability and privacy issues for example:
- If the list of the CA names is longer than the peers input buffer then
the handshake will fail
- If the configured CAs belong to third parties, this message gives away
information on the relations to these third parties
Therefore we introduce an option to suppress the CA list in the
Certificate Request message.
Providing this feature as a runtime option comes with a little cost in
code size and advantages in maintenance and flexibility.
This commit changes `ssl_parse_signature_algorithms_ext` to remember
one suitable ( := supported by client and by our config ) hash
algorithm per signature algorithm.
It also modifies the ciphersuite checking function
`ssl_ciphersuite_match` to refuse a suite if there
is no suitable hash algorithm.
Finally, it adds the corresponding entry to the ChangeLog.
The routine `mbedtls_ssl_write_server_key_exchange` heavily depends on
what kind of cipher suite is active: some don't need a
ServerKeyExchange at all, some need (EC)DH parameters but no server
signature, some require both. Each time we want to restrict a certain
piece of code to some class of ciphersuites, it is guarded by a
lengthy concatentation of configuration checks determining whether at
least one of the relevant cipher suites is enabled in the config; on
the code level, it is guarded by the check whether one of these
cipher suites is the active one.
To ease readability of the code, this commit introduces several helper
macros and helper functions that can be used to determine whether a
certain class of ciphersuites (a) is active in the config, and
(b) contains the currently present ciphersuite.
With this commit the Elliptic Curve Point interface is rewised. Two
compile time options has been removed to simplify the interface and
the function names got a new prefix that indicates that these functions
are for internal use and not part of the public interface.
The intended use of the abstraction layer for Elliptic Curve Point
arithmetic is to enable using hardware cryptographic accelerators.
These devices are a shared resource and the driver code rarely provides
thread safety.
This commit adds mutexes to the abstraction layer to protect the device
in a multi-threaded environment.
The primary use case behind providing an abstraction layer to enable
alternative Elliptic Curve Point arithmetic implementation, is making
use of cryptographic acceleration hardware if it is present.
To provide thread safety for the hardware accelerator we need a mutex
to guard it.
The compile time macros enabling the initialisation and deinitialisation
in the alternative Elliptic Curve Point arithmetic implementation had
names that did not end with '_ALT' as required by check-names.sh.
This patch introduces some additional checks in the PK module for 64-bit
systems only. The problem is that the API functions in the PK
abstraction accept a size_t value for the hashlen, while the RSA module
accepts an unsigned int for the hashlen. Instead of silently casting
size_t to unsigned int, this change checks whether the hashlen overflows
an unsigned int and returns an error.
The test case was generated by modifying our signature code so that it
produces a 7-byte long padding (which also means garbage at the end, so it is
essential in to check that the error that is detected first is indeed the
padding rather than the final length check).
In many places in TLS handling, some code detects a fatal error, sends
a fatal alert message, and returns to the caller. If sending the alert
fails, then return the error that triggered the alert, rather than
overriding the return status. This effectively causes alert sending
failures to be ignored. Formerly the code was inconsistently sometimes
doing one, sometimes the other.
In general ignoring the alert is the right thing: what matters to the
caller is the original error. A typical alert failure is that the
connection is already closed.
One case which remains not handled correctly is if the alert remains
in the output buffer (WANT_WRITE). Then it won't be sent, or will be
truncated. We'd need to either delay the application error or record
the write buffering notice; to be done later.
