Fix Secure Session serialization format #658
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secure_session_save() saves short serialized Secure Session state. That is, it writes "is_client" as 4-byte value while its size in SESSION_CTX_SERIZALIZED_SIZE is computed as sizeof(bool) which is 1 byte on most platforms. This causes 3 least significant bytes of "in_seq" being missing from the serialized data. Correct size of Secure Session state is 60 bytes, we report only 57. This issue is not detected by unit tests of JavaThemis -- the only high-level wrapper supporting this interface -- which works only because the allocated memory for the output array is slightly bigger than requested 57 bytes, extra 3 bytes written past-the-end remain there in RAM and the unit test generally works, if the data stays where it is. However, sometimes garbage collection occurs at the right moment and the issue manifests itself as a failing Secure Session test. Now the output size is reported correctly and all Secure Session data is written within the allocated bounds.
ilammy
added
bug
core
4 tasks
While we're here and touching this code anyway, let's correct the name of the constant too.
vixentael
approved these changes
Jun 16, 2020
| (sizeof((ctx)->session_id) + sizeof((ctx)->is_client) + sizeof((ctx)->session_master_key) \ | ||
| + sizeof((ctx)->out_seq) + sizeof((ctx)->in_seq)) | ||
| /* | ||
| * Data layout of serialized Secure Session state looks like this: |
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woa, that looks amazing!
| */ | ||
|
|
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| #define SESSION_CTX_SERIALIZED_SIZE \ | ||
| (2 * sizeof(uint32_t) + SESSION_MASTER_KEY_LENGTH + 2 * sizeof(uint32_t)) |
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secure_session_save() saves short serialized Secure Session state.
That is, it writes
is_clientas 4-byte value while its size in SESSION_CTX_SERIZALIZED_SIZE is computed assizeof(bool)which is 1 byte on most platforms. This causes 3 least significant bytes ofin_seqbeing missing from the serialized data.Correct size of Secure Session state is 60 bytes, we report only 57.
This issue is not detected by unit tests of JavaThemis—the only high-level wrapper supporting this interface—which works only because the allocated memory for the output array is slightly bigger than requested 57 bytes, extra 3 bytes written past-the-end remain there in RAM and the unit test generally works, if the data stays where it is. However, sometimes garbage collection occurs at the right moment and the issue manifests itself as a failing Secure Session test.
Now the output size is reported correctly and all Secure Session data is written within the allocated bounds.
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