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Fix boolean options in the wrong section

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Boolean options that modify the behavior of a module are supposed to be in
the "feature support" section, not in the "configuration options" support:
that section is documented to contain commented-out definitions with a
value, for which the comment contains the default version. In particular,
merely uncommenting a definition in the "configuration options" section is
not supposed to change anything.

Move the offending boolean options to the proper section.

This causes those options to be enabled by `config.py full` unless
explicitly excluded. For the moved options:

* Everest is already explicitly excluded.
* The ALT options need to link against a custom function, so exclude them.
* `MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE` is ok for testing, and is
  currently never tested in `all.sh`. With this commit, we will now test the
  library with it enabled in configurations based on `full`.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine
2023-09-07 17:40:16 +02:00
parent 06c466d869
commit 937b91eb6f
2 changed files with 70 additions and 66 deletions
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130
include/mbedtls/config.h
View File

@@ -265,6 +265,45 @@
//#define MBEDTLS_PLATFORM_NV_SEED_ALT
//#define MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT
/**
* Uncomment the macro to let Mbed TLS use your alternate implementation of
* mbedtls_platform_gmtime_r(). This replaces the default implementation in
* platform_util.c.
*
* gmtime() is not a thread-safe function as defined in the C standard. The
* library will try to use safer implementations of this function, such as
* gmtime_r() when available. However, if Mbed TLS cannot identify the target
* system, the implementation of mbedtls_platform_gmtime_r() will default to
* using the standard gmtime(). In this case, calls from the library to
* gmtime() will be guarded by the global mutex mbedtls_threading_gmtime_mutex
* if MBEDTLS_THREADING_C is enabled. We recommend that calls from outside the
* library are also guarded with this mutex to avoid race conditions. However,
* if the macro MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, Mbed TLS will
* unconditionally use the implementation for mbedtls_platform_gmtime_r()
* supplied at compile time.
*/
//#define MBEDTLS_PLATFORM_GMTIME_R_ALT
/**
* Uncomment the macro to let mbed TLS use your alternate implementation of
* mbedtls_platform_zeroize(). This replaces the default implementation in
* platform_util.c.
*
* mbedtls_platform_zeroize() is a widely used function across the library to
* zero a block of memory. The implementation is expected to be secure in the
* sense that it has been written to prevent the compiler from removing calls
* to mbedtls_platform_zeroize() as part of redundant code elimination
* optimizations. However, it is difficult to guarantee that calls to
* mbedtls_platform_zeroize() will not be optimized by the compiler as older
* versions of the C language standards do not provide a secure implementation
* of memset(). Therefore, MBEDTLS_PLATFORM_ZEROIZE_ALT enables users to
* configure their own implementation of mbedtls_platform_zeroize(), for
* example by using directives specific to their compiler, features from newer
* C standards (e.g using memset_s() in C11) or calling a secure memset() from
* their system (e.g explicit_bzero() in BSD).
*/
//#define MBEDTLS_PLATFORM_ZEROIZE_ALT
/**
* \def MBEDTLS_DEPRECATED_WARNING
*
@@ -818,6 +857,15 @@
*/
#define MBEDTLS_REMOVE_3DES_CIPHERSUITES
/**
* Enable the verified implementations of ECDH primitives from Project Everest
* (currently only Curve25519). This feature changes the layout of ECDH
* contexts and therefore is a compatibility break for applications that access
* fields of a mbedtls_ecdh_context structure directly. See also
* MBEDTLS_ECDH_LEGACY_CONTEXT in include/mbedtls/ecdh.h.
*/
//#define MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED
/**
* \def MBEDTLS_ECP_DP_SECP192R1_ENABLED
*
@@ -2117,6 +2165,23 @@
*/
//#define MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH
/**
* Allow SHA-1 in the default TLS configuration for TLS 1.2 handshake
* signature and ciphersuite selection. Without this build-time option, SHA-1
* support must be activated explicitly through mbedtls_ssl_conf_sig_hashes.
* The use of SHA-1 in TLS <= 1.1 and in HMAC-SHA-1 is always allowed by
* default. At the time of writing, there is no practical attack on the use
* of SHA-1 in handshake signatures, hence this option is turned on by default
* to preserve compatibility with existing peers, but the general
* warning applies nonetheless:
*
* \warning SHA-1 is considered a weak message digest and its use constitutes
* a security risk. If possible, we recommend avoiding dependencies
* on it, and considering stronger message digests instead.
*
*/
//#define MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE
/**
* \def MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN
*
@@ -4141,71 +4206,6 @@
//#define MBEDTLS_X509_MAX_INTERMEDIATE_CA 8 /**< Maximum number of intermediate CAs in a verification chain. */
//#define MBEDTLS_X509_MAX_FILE_PATH_LEN 512 /**< Maximum length of a path/filename string in bytes including the null terminator character ('\0'). */
/**
* Allow SHA-1 in the default TLS configuration for TLS 1.2 handshake
* signature and ciphersuite selection. Without this build-time option, SHA-1
* support must be activated explicitly through mbedtls_ssl_conf_sig_hashes.
* The use of SHA-1 in TLS <= 1.1 and in HMAC-SHA-1 is always allowed by
* default. At the time of writing, there is no practical attack on the use
* of SHA-1 in handshake signatures, hence this option is turned on by default
* to preserve compatibility with existing peers, but the general
* warning applies nonetheless:
*
* \warning SHA-1 is considered a weak message digest and its use constitutes
* a security risk. If possible, we recommend avoiding dependencies
* on it, and considering stronger message digests instead.
*
*/
//#define MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE
/**
* Uncomment the macro to let mbed TLS use your alternate implementation of
* mbedtls_platform_zeroize(). This replaces the default implementation in
* platform_util.c.
*
* mbedtls_platform_zeroize() is a widely used function across the library to
* zero a block of memory. The implementation is expected to be secure in the
* sense that it has been written to prevent the compiler from removing calls
* to mbedtls_platform_zeroize() as part of redundant code elimination
* optimizations. However, it is difficult to guarantee that calls to
* mbedtls_platform_zeroize() will not be optimized by the compiler as older
* versions of the C language standards do not provide a secure implementation
* of memset(). Therefore, MBEDTLS_PLATFORM_ZEROIZE_ALT enables users to
* configure their own implementation of mbedtls_platform_zeroize(), for
* example by using directives specific to their compiler, features from newer
* C standards (e.g using memset_s() in C11) or calling a secure memset() from
* their system (e.g explicit_bzero() in BSD).
*/
//#define MBEDTLS_PLATFORM_ZEROIZE_ALT
/**
* Uncomment the macro to let Mbed TLS use your alternate implementation of
* mbedtls_platform_gmtime_r(). This replaces the default implementation in
* platform_util.c.
*
* gmtime() is not a thread-safe function as defined in the C standard. The
* library will try to use safer implementations of this function, such as
* gmtime_r() when available. However, if Mbed TLS cannot identify the target
* system, the implementation of mbedtls_platform_gmtime_r() will default to
* using the standard gmtime(). In this case, calls from the library to
* gmtime() will be guarded by the global mutex mbedtls_threading_gmtime_mutex
* if MBEDTLS_THREADING_C is enabled. We recommend that calls from outside the
* library are also guarded with this mutex to avoid race conditions. However,
* if the macro MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, Mbed TLS will
* unconditionally use the implementation for mbedtls_platform_gmtime_r()
* supplied at compile time.
*/
//#define MBEDTLS_PLATFORM_GMTIME_R_ALT
/**
* Enable the verified implementations of ECDH primitives from Project Everest
* (currently only Curve25519). This feature changes the layout of ECDH
* contexts and therefore is a compatibility break for applications that access
* fields of a mbedtls_ecdh_context structure directly. See also
* MBEDTLS_ECDH_LEGACY_CONTEXT in include/mbedtls/ecdh.h.
*/
//#define MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED
/** \} name SECTION: Module configuration options */
/* Target and application specific configurations

6
scripts/config.py
View File

@@ -225,7 +225,11 @@ def is_seamless_alt(name):
Exclude alternative implementations of library functions since they require
an implementation of the relevant functions and an xxx_alt.h header.
"""
if name == 'MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT':
if name in (
'MBEDTLS_PLATFORM_GMTIME_R_ALT',
'MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT',
'MBEDTLS_PLATFORM_ZEROIZE_ALT',
):
# Similar to non-platform xxx_ALT, requires platform_alt.h
return False
return name.startswith('MBEDTLS_PLATFORM_')