Allow TLS configuration when no TRGN or NV seed

[c1728p9]

Description

Remove the code which forces the no entropy configuration when
MBEDTLS_ENTROPY_HARDWARE_ALT is not defined. This makes it possible for
users to turn on null entropy from the configuration system.

Related PRs

#2843

Related issues

#2914
ARMmbed/mbed-os-example-client#83
ARMmbed/mbed-os-example-client#84

Todos

• Tests

[c1728p9]

/morph test

[bridadan]

/morph test

[mbed-bot]

Result: FAILURE

Your command has finished executing! Here's what you wrote!

/morph test

Output

mbed Build Number: 1050

Test Prep failed!

[bridadan]

/morph test

[mbed-bot]

Result: SUCCESS

Your command has finished executing! Here's what you wrote!

/morph test

Output

mbed Build Number: 1055

All builds and test passed!

[sg-]

This has a problem linking mbed-client-testapp

Link: mbed-client-testapp
./BUILD/k64f/gcc_arm/mbed-os/features/mbedtls/src/pk.o: In function `mbedtls_pk_verify_ext':
pk.c:(.text.mbedtls_pk_verify_ext+0x68): undefined reference to `mbedtls_rsa_rsassa_pss_verify_ext'
./BUILD/k64f/gcc_arm/mbed-os/features/mbedtls/src/pk_wrap.o: In function `rsa_free_wrap':
pk_wrap.c:(.text.rsa_free_wrap+0x4): undefined reference to `mbedtls_rsa_free'
./BUILD/k64f/gcc_arm/mbed-os/features/mbedtls/src/pk_wrap.o: In function `rsa_alloc_wrap':
pk_wrap.c:(.text.rsa_alloc_wrap+0x12): undefined reference to `mbedtls_rsa_init'
./BUILD/k64f/gcc_arm/mbed-os/features/mbedtls/src/pk_wrap.o: In function `rsa_check_pair_wrap':
pk_wrap.c:(.text.rsa_check_pair_wrap+0x0): undefined reference to `mbedtls_rsa_check_pub_priv'
./BUILD/k64f/gcc_arm/mbed-os/features/mbedtls/src/pk_wrap.o: In function `rsa_encrypt_wrap':
pk_wrap.c:(.text.rsa_encrypt_wrap+0x22): undefined reference to `mbedtls_rsa_pkcs1_encrypt'
./BUILD/k64f/gcc_arm/mbed-os/features/mbedtls/src/pk_wrap.o: In function `rsa_decrypt_wrap':
pk_wrap.c:(.text.rsa_decrypt_wrap+0x22): undefined reference to `mbedtls_rsa_pkcs1_decrypt'
...

[0xc0170]

I think this bug should be fixed via #2926 ? @andresag01 can you provide details please

[simonbutcher]

The bug is better fixed by #2926, which fixes the issue properly.

Otherwise there are several issues with this PR:

• This pull request changes an imported file, so will be overwritten on the next import of mbed TLS. Fixes to mbed TLS MUST be done upstream.
• This change will break mbed TLS on all platforms that don't have an entropy source, which in turn will break the mbed test suite.

Please close this PR and evaluate #2926 instead.