Remove support for OOT (out-of-tree) SGX driver

[woju]

Description of the changes

See commit message.

How to test this PR?

CI.

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This change is 

[mkow]

Reviewed 49 of 49 files at r1, all commit messages.
Reviewable status: all files reviewed, 3 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (1 more required, approved so far: ITL) (waiting on @woju)

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debian/control line 13 at r1 (raw file):

 libprotobuf-c-dev,
 libsgx-dcap-quote-verify-dev,
 linux-libc-dev (>= 5.11) | linux-headers-amd64 (>= 5.11),

Don't we need linux-headers for sgx.h? Where does sgx.h come from?

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pal/src/host/linux-sgx/host_framework.c line 551 at r1 (raw file):

int init_enclave(sgx_arch_secs_t* secs, sgx_sigstruct_t* sigstruct, sgx_arch_token_t* token) {
#ifndef CONFIG_SGX_DRIVER_OOT
    __UNUSED(token);

Now we can just remove this argument.

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pal/src/host/linux-sgx/host_main.c line 224 at r1 (raw file):

    log_debug("Token file: %s", token_path);

    ret = read_enclave_token(token_fd, enclave_token);

read_enclave_token() is unused now

[efu39]

Reviewed 49 of 49 files at r1, all commit messages.
Reviewable status: all files reviewed, 6 unresolved discussions, not enough approvals from maintainers (2 more required), not enough approvals from different teams (1 more required, approved so far: ITL) (waiting on @woju)

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pal/src/host/linux-sgx/host_main.c line 204 at r1 (raw file):

static int get_enclave_token(sgx_arch_token_t* enclave_token, sgx_sigstruct_t* enclave_sigstruct) {
    return create_dummy_enclave_token(enclave_sigstruct, enclave_token);
}

Since the get_enclave_token function is only creating a dummy token, wondering if the function and the code related to the generated dummy token can all be removed.

Code quote:

static int get_enclave_token(sgx_arch_token_t* enclave_token, sgx_sigstruct_t* enclave_sigstruct) {
    return create_dummy_enclave_token(enclave_sigstruct, enclave_token);
}

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pal/src/host/linux-sgx/host_main.c line 274 at r1 (raw file):

        log_error("Reading enclave token failed: %s", unix_strerror(ret));
        goto out;
    }

The error message should be updated (or removed?), the function is no longer reading token file. Also create_dummy_enclave_token() never returns ret < 0

Code quote:

    ret = get_enclave_token(&enclave_token, &enclave_sigstruct);
    if (ret < 0) {
        log_error("Reading enclave token failed: %s", unix_strerror(ret));
        goto out;
    }

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pal/src/host/linux-sgx/host_main.c line 278 at r1 (raw file):

#ifdef DEBUG
    if (enclave->profile_enable) {
        if (!(enclave_token.body.attributes.flags & SGX_FLAGS_DEBUG)) {

Maybe consider checkingenclave_sigstruct.body instead since the dummy token value was derived from it?