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100 lines
4.6 KiB
Markdown
100 lines
4.6 KiB
Markdown
Testing strategy for `MBEDTLS_USE_PSA_CRYPTO`
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=============================================
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This document records the testing strategy used so far in implementing
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`MBEDTLS_USE_PSA_CRYPTO`.
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General considerations
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----------------------
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There needs to be at least one build in `all.sh` that enables
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`MBEDTLS_USE_PSA_CRYPTO` and runs the full battery of tests; currently that's
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ensured by the fact that `scripts/config.py full` enables
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`MBEDTLS_USE_PSA_CRYPTO`. There needs to be at least one build with
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`MBEDTLS_USE_PSA_CRYPTO` disabled (as long as it's optional); currently that's
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ensured by the fact that it's disabled in the default config.
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Generally, code review is enough to ensure that PSA APIs are indeed used where
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they should be when `MBEDTLS_USE_PSA_CRYPTO` is enabled.
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However, when it comes to TLS, we also have the option of using debug messages
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to confirm which code path is taken. This is generally unnecessary, except when
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a decision is made at run-time about whether to use the PSA or legacy code
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path. (For example, for record protection, previously (until 3.1), some ciphers were supported
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via PSA while some others weren't, with a run-time fallback. In this case, it's
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good to have a debug message checked by the test case to confirm that the
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right decision was made at run-time, i. e. that we didn't use the fallback for
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ciphers that are supposed to be supported.)
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New APIs meant for application use
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----------------------------------
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For example, `mbedtls_pk_setup_opaque()` is meant to be used by applications
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in order to create PK contexts that can then be passed to existing TLS and
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X.509 APIs (which remain unchanged).
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In that case, we want:
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- unit testing of the new API and directly-related APIs - for example:
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- in `test_suite_pk` we have a new test function `pk_psa_utils` that exercises
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`mbedtls_pk_setup_opaque()` and checks that various utility functions
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(`mbedtls_pk_get_type()` etc.) work and the functions that are expected to
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fail (`mbedtls_pk_verify()` etc) return the expected error.
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- in `test_suite_pk` we modified the existing `pk_psa_sign` test function to
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check that signature generation works as expected
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- in `test_suite_pkwrite` we should have a new test function checking that
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exporting (writing out) the public part of the key works as expected and
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that exporting the private key fails as expected.
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- integration testing of the new API with each existing API which should
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accepts a context created this way - for example:
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- in `programs/ssl/ssl_client2` a new option `key_opaque` that causes the
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new API to be used, and one or more tests in `ssl-opt.sh` using that.
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(We should have the same server-side.)
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- in `test_suite_x509write` we have a new test function
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`x509_csr_check_opaque()` checking integration of the new API with the
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existing `mbedtls_x509write_csr_set_key()`. (And also
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`mbedtls_x509write_crt_set_issuer_key()` since #5710.)
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For some APIs, for example with `mbedtls_ssl_conf_psk_opaque()`, testing in
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`test_suite_ssl` was historically not possible, so we only have testing in
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`ssl-opt.sh`.
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New APIs meant for internal use
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-------------------------------
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For example, `mbedtls_cipher_setup_psa()` (no longer used, soon to be
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deprecated - #5261) was meant to be used by the TLS layer, but probably not
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directly by applications.
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In that case, we want:
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- unit testing of the new API and directly-related APIs - for example:
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- in `test_suite_cipher`, the existing test functions `auth_crypt_tv` and
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`test_vec_crypt` gained a new parameter `use_psa` and corresponding test
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cases
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- integration testing:
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- usually already covered by existing tests for higher-level modules:
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- for example simple use of `mbedtls_cipher_setup_psa()` in TLS is already
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covered by running the existing TLS tests in a build with
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`MBEDTLS_USA_PSA_CRYPTO` enabled
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- however if use of the new API in higher layers involves more logic that
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use of the old API, specific integrations test may be required
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- for example, the logic to fall back from `mbedtls_cipher_setup_psa()` to
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`mbedtls_cipher_setup()` in TLS is tested by `run_test_psa` in
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`ssl-opt.sh`.
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Internal changes
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----------------
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For example, use of PSA to compute the TLS 1.2 PRF.
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Changes in this category rarely require specific testing, as everything should
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be already be covered by running the existing tests in a build with
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`MBEDTLS_USE_PSA_CRYPTO` enabled; however we need to make sure the existing
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test have sufficient coverage, and improve them if necessary.
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However, if additional logic is involved, or there are run-time decisions about
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whether to use the PSA or legacy code paths, specific tests might be in order.
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