ktls: support aes256

[lrstewart]

Description of changes:

Adds support for AES256 GCM, as well as refactors how ciphers are supported to make future ciphers easier to add.

After this change, support for new ciphers can be added by appending the new crypto_info to the union in s2n_ktls_crypto_info and implementing the cipher set_ktls_info function. Theoretically the new union member in s2n_ktls_crypto_info is optional: we could allocate the memory for the crypto_info on the heap instead, but the union is an easy way to avoid that.

Call-outs:

To avoid the conditional compilation leaking into more files in /crypto, I made versions of the symbols that ktls needs for crypto_info available even without ktls support.

Testing:

Rewrote the unit tests to use the new cipher method, + added tests of each cipher to the self-talk test.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[camshaft]

great idea!

[justinr1234]

@lrstewart Any help with this would be greatly appreciated!

Starting with this commit I can't build anymore in a clean docker env on linux (arm64 and amd64 both):

[  0%] Building C object CMakeFiles/s2n.dir/crypto/s2n_aead_cipher_aes_gcm.c.o
In file included from /opt/s2n-tls/crypto/s2n_cipher.h:26,
                 from /opt/s2n-tls/crypto/s2n_aead_cipher_aes_gcm.c:19:
/opt/s2n-tls/crypto/s2n_ktls_crypto.h:55:48: error: field 'aes_gcm_256' has incomplete type
         s2n_ktls_crypto_info_tls12_aes_gcm_256 aes_gcm_256;
                                                ^~~~~~~~~~~
/opt/s2n-tls/crypto/s2n_aead_cipher_aes_gcm.c: In function 's2n_aead_cipher_aes256_gcm_set_ktls_info':
/opt/s2n-tls/crypto/s2n_aead_cipher_aes_gcm.c:421:16: error: dereferencing pointer to incomplete type 's2n_ktls_crypto_info_tls12_aes_gcm_256' {aka 'struct tls12_crypto_info_aes_gcm_256'}
     crypto_info->info.version = TLS_1_2_VERSION;
                ^~
/opt/s2n-tls/crypto/s2n_aead_cipher_aes_gcm.c:422:37: error: 'TLS_CIPHER_AES_GCM_256' undeclared (first use in this function); did you mean 'TLS_CIPHER_AES_GCM_128'?
     crypto_info->info.cipher_type = TLS_CIPHER_AES_GCM_256;
                                     ^~~~~~~~~~~~~~~~~~~~~~
                                     TLS_CIPHER_AES_GCM_128
/opt/s2n-tls/crypto/s2n_aead_cipher_aes_gcm.c:422:37: note: each undeclared identifier is reported only once for each function it appears in
In file included from /opt/s2n-tls/error/s2n_errno.h:23,
                 from /opt/s2n-tls/utils/s2n_safety.h:23,
                 from /opt/s2n-tls/crypto/s2n_ecc_evp.h:24,
                 from /opt/s2n-tls/crypto/s2n_ecdsa.h:22,
                 from /opt/s2n-tls/crypto/s2n_pkey.h:20,
                 from /opt/s2n-tls/crypto/s2n_certificate.h:22,
                 from /opt/s2n-tls/tls/s2n_crypto.h:18,
                 from /opt/s2n-tls/crypto/s2n_aead_cipher_aes_gcm.c:21:
/opt/s2n-tls/crypto/s2n_aead_cipher_aes_gcm.c:444:20: error: invalid application of 'sizeof' to incomplete type 's2n_ktls_crypto_info_tls12_aes_gcm_256' {aka 'struct tls12_crypto_info_aes_gcm_256'}
             sizeof(s2n_ktls_crypto_info_tls12_aes_gcm_256)));
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/s2n-tls/utils/s2n_ensure.h:35:15: note: in definition of macro '__S2N_ENSURE'
         if (!(cond)) {             \
               ^~~~
/opt/s2n-tls/crypto/s2n_aead_cipher_aes_gcm.c:443:5: note: in expansion of macro 'RESULT_GUARD_POSIX'
     RESULT_GUARD_POSIX(s2n_blob_init(&out->value, (uint8_t *) (void *) crypto_info,
     ^~~~~~~~~~~~~~~~~~
make[2]: *** [CMakeFiles/s2n.dir/build.make:63: CMakeFiles/s2n.dir/crypto/s2n_aead_cipher_aes_gcm.c.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:8665: CMakeFiles/s2n.dir/all] Error 2
make: *** [Makefile:141: all] Error 2
The command '/bin/sh -c S2N_DONT_MLOCK=1 make' returned a non-zero code: 2

[lrstewart]

Try this patch: https://gist.github.com/lrstewart/42e91a507cfed98263b646520930dfb3 Let me know if that works and I'll put out a PR

[camshaft]

this should be addressed in #4295