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modules: mbedtls: Expose MBEDTLS_PLATFORM_NO_STD_FUNCTIONS

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The commit adds Kconfig options that allows users to select
 - MBEDTLS_PLATFORM_NO_STD_FUNCTIONS
 - MBEDTLS_PLATFORM_SNPRINTF_ALT
allowing Mbed TLS to use alternative definitions of STD functions.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
This commit is contained in:
Dominik Ermel 2025-03-14 17:39:41 +00:00 • committed by Benjamin Cabé
commit 350a223321
2 changed files with 30 additions and 0 deletions
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22
modules/mbedtls/Kconfig.mbedtls
View file

@ -378,6 +378,28 @@ config MBEDTLS_GENPRIME_ENABLED
config MBEDTLS_ASN1_PARSE_C
bool "Support for ASN1 parser functions"
config MBEDTLS_PLATFORM_NO_STD_FUNCTIONS
bool "Remove usage of standard libc functions"
help
This prevents Mbed TLS from linking against the following standard functions
from libc: `snprintf`, `vsnprintf`, `printf`, `fprintf`, `calloc`, `free`, `setbuf`, `exit`
and `time`. By default Mbed TLS will use stub functions for all these functions.
These stubs are just meant to return successfully, but they don't implement
the required functionality.
Users can individually override each of these stubs by calling
`mbedtls_platform_set_xxx()` to set the their implementation of `xxx()` function
at runtime.
if MBEDTLS_PLATFORM_NO_STD_FUNCTIONS
config MBEDTLS_PLATFORM_SNPRINTF_ALT
bool "Allow setting custom snprintf at run-time"
help
Allow setting a custom `snprintf()` function with `mbedtls_platform_set_snprintf()`.
Include `mbedtls/platform.h` for the prototype of this function.
endif # MBEDTLS_PLATFORM_NO_STD_FUNCTIONS
config MBEDTLS_PEM_CERTIFICATE_FORMAT
bool "Support for PEM certificate format"
help

8
modules/mbedtls/configs/config-mbedtls.h
View file

@ -23,6 +23,14 @@
#define MBEDTLS_PLATFORM_ZEROIZE_ALT
#endif
#if defined(CONFIG_MBEDTLS_PLATFORM_NO_STD_FUNCTIONS)
#define MBEDTLS_PLATFORM_NO_STD_FUNCTIONS
#endif /* defined(MBEDTLS_PLATFORM_NO_STD_FUNCTIONS) */
#if defined(CONFIG_MBEDTLS_PLATFORM_SNPRINTF_ALT)
#define MBEDTLS_PLATFORM_SNPRINTF_ALT
#endif /* defined(MBEDTLS_PLATFORM_SNPRINTF_ALT) */
#if defined(CONFIG_MBEDTLS_ENTROPY_POLL_ZEPHYR)
#define MBEDTLS_ENTROPY_HARDWARE_ALT
#else