Log Message:
mbedtls: Update to 2.23.0

= mbed TLS 2.23.0 branch released 2020-07-01

Default behavior changes
   * In the experimental PSA secure element interface, change the encoding of
     key lifetimes to encode a persistence level and the location. Although C
     prototypes do not effectively change, code calling
     psa_register_se_driver() must be modified to pass the driver's location
     instead of the keys' lifetime. If the library is upgraded on an existing
     device, keys created with the old lifetime value will not be readable or
     removable through Mbed TLS after the upgrade.

Features
   * New functions in the error module return constant strings for
     high- and low-level error codes, complementing mbedtls_strerror()
     which constructs a string for any error code, including compound
     ones, but requires a writable buffer. Contributed by Gaurav Aggarwal
     in #3176.
   * The new utility programs/ssl/ssl_context_info prints a human-readable
     dump of an SSL context saved with mbedtls_ssl_context_save().
   * Add support for midipix, a POSIX layer for Microsoft Windows.
   * Add new mbedtls_x509_crt_parse_der_with_ext_cb() routine which allows
     parsing unsupported certificate extensions via user provided callback.
     Contributed by Nicola Di Lieto <nicola.dilieto@gmail.com> in #3243 as
     a solution to #3241.
   * Pass the "certificate policies" extension to the callback supplied to
     mbedtls_x509_crt_parse_der_with_ext_cb() if it contains unsupported
     policies (#3419).
   * Added support to entropy_poll for the kern.arandom syscall supported on
     some BSD systems. Contributed by Nia Alarie in #3423.
   * Add support for Windows 2000 in net_sockets. Contributed by opatomic. #3239

Security
   * Fix a side channel vulnerability in modular exponentiation that could
     reveal an RSA private key used in a secure enclave. Noticed by Sangho Lee,
     Ming-Wei Shih, Prasun Gera, Taesoo Kim and Hyesoon Kim (Georgia Institute
     of Technology); and Marcus Peinado (Microsoft Research). Reported by Raoul
     Strackx (Fortanix) in #3394.
   * Fix side channel in mbedtls_ecp_check_pub_priv() and
     mbedtls_pk_parse_key() / mbedtls_pk_parse_keyfile() (when loading a
     private key that didn't include the uncompressed public key), as well as
     mbedtls_ecp_mul() / mbedtls_ecp_mul_restartable() when called with a NULL
     f_rng argument. An attacker with access to precise enough timing and
     memory access information (typically an untrusted operating system
     attacking a secure enclave) could fully recover the ECC private key.
     Found and reported by Alejandro Cabrera Aldaya and Billy Brumley.
   * Fix issue in Lucky 13 counter-measure that could make it ineffective when
     hardware accelerators were used (using one of the MBEDTLS_SHAxxx_ALT
     macros). This would cause the original Lucky 13 attack to be possible in
     those configurations, allowing an active network attacker to recover
     plaintext after repeated timing measurements under some conditions.
     Reported and fix suggested by Luc Perneel in #3246.

Bugfix
   * Fix the Visual Studio Release x64 build configuration for mbedtls itself.
     Completes a previous fix in Mbed TLS 2.19 that only fixed the build for
     the example programs. Reported in #1430 and fix contributed by irwir.
   * Fix undefined behavior in X.509 certificate parsing if the
     pathLenConstraint basic constraint value is equal to INT_MAX.
     The actual effect with almost every compiler is the intended
     behavior, so this is unlikely to be exploitable anywhere. #3192
   * Fix issue with a detected HW accelerated record error not being exposed
     due to shadowed variable. Contributed by Sander Visser in #3310.
   * Avoid NULL pointer dereferencing if mbedtls_ssl_free() is called with a
     NULL pointer argument. Contributed by Sander Visser in #3312.
   * Fix potential linker errors on dual world platforms by inlining
     mbedtls_gcc_group_to_psa(). This allows the pk.c module to link separately
     from psa_crypto.c. Fixes #3300.
   * Remove dead code in X.509 certificate parsing. Contributed by irwir in
     #2855.
   * Include asn1.h in error.c. Fixes #3328 reported by David Hu.
   * Fix potential memory leaks in ecp_randomize_jac() and ecp_randomize_mxz()
     when PRNG function fails. Contributed by Jonas Lejeune in #3318.
   * Remove unused macros from MSVC projects. Reported in #3297 and fix
     submitted in #3333 by irwir.
   * Add additional bounds checks in ssl_write_client_hello() preventing
     output buffer overflow if the configuration declared a buffer that was
     too small.
   * Set _POSIX_C_SOURCE to at least 200112L in C99 code. Reported in #3420 and
     fix submitted in #3421 by Nia Alarie.
   * Fix building library/net_sockets.c and the ssl_mail_client program on
     NetBSD. Contributed by Nia Alarie in #3422.
   * Fix false positive uninitialised variable reported by cpp-check.
     Contributed by Sander Visser in #3311.
   * Update iv and len context pointers manually when reallocating buffers
     using the MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH feature. This caused issues
     when receiving a connection with CID, when these fields were shifted
     in ssl_parse_record_header().

Changes
   * Fix warnings about signedness issues in format strings. The build is now
     clean of -Wformat-signedness warnings. Contributed by Kenneth Soerensen
     in #3153.
   * Fix minor performance issue in operations on Curve25519 caused by using a
     suboptimal modular reduction in one place. Found and fix contributed by
     Aurelien Jarno in #3209.
   * Combine identical cases in switch statements in md.c. Contributed
     by irwir in #3208.
   * Simplify a bounds check in ssl_write_certificate_request(). Contributed
     by irwir in #3150.
   * Unify the example programs termination to call mbedtls_exit() instead of
     using a return command. This has been done to enable customization of the
     behavior in bare metal environments.
   * Fix mbedtls_x509_dn_gets to escape non-ASCII characters as "?".
     Contributed by Koh M. Nakagawa in #3326.
   * Use FindPython3 when cmake version >= 3.15.0
   * Abort the ClientHello writing function as soon as some extension doesn't
     fit into the record buffer. Previously, such extensions were silently
     dropped. As a consequence, the TLS handshake now fails when the output
     buffer is not large enough to hold the ClientHello.
   * The unit tests now rely on header files in tests/include/test and source
     files in tests/src. When building with make or cmake, the files in
     tests/src are compiled and the resulting object linked into each test
     executable.
   * The ECP module, enabled by `MBEDTLS_ECP_C`, now depends on
     `MBEDTLS_CTR_DRBG_C` or `MBEDTLS_HMAC_DRBG_C` for some side-channel
     coutermeasures. If side channels are not a concern, this dependency can
     be avoided by enabling the new option `MBEDTLS_ECP_NO_INTERNAL_RNG`.
   * Align MSVC error flag with GCC and Clang. Contributed by Carlos Gomes
     Martinho. #3147
   * Remove superfluous assignment in mbedtls_ssl_parse_certificate(). Reported
     in #3182 and fix submitted by irwir. #3217
   * Fix typo in XTS tests. Reported and fix submitted by Kxuan. #3319