Hi Reinette,
-----Original Message----- From: Chatre, Reinette reinette.chatre@intel.com Sent: Tuesday, August 16, 2022 9:35 PM To: Dhanraj, Vijay vijay.dhanraj@intel.com; Jarkko Sakkinen jarkko@kernel.org Cc: Dave Hansen dave.hansen@linux.intel.com; linux- sgx@vger.kernel.org; Shuah Khan shuah@kernel.org; open list:KERNEL SELFTEST FRAMEWORK linux-kselftest@vger.kernel.org; open list <linux- kernel@vger.kernel.org> Subject: Re: [PATCH 2/2] selftests/sgx: Add SGX selftest augment_via_eaccept_long
Hi Vijay,
On 8/16/2022 6:27 PM, Dhanraj, Vijay wrote:
Hi Jarkko, Reinette,
-----Original Message----- From: Jarkko Sakkinen jarkko@kernel.org Sent: Tuesday, August 16, 2022 4:34 PM To: Chatre, Reinette reinette.chatre@intel.com Cc: Dave Hansen dave.hansen@linux.intel.com; linux- sgx@vger.kernel.org; Dhanraj, Vijay vijay.dhanraj@intel.com; Shuah Khan shuah@kernel.org; open list:KERNEL SELFTEST FRAMEWORK
<linux-
kselftest@vger.kernel.org>; open list linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] selftests/sgx: Add SGX selftest augment_via_eaccept_long
On Tue, Aug 16, 2022 at 09:26:40AM -0700, Reinette Chatre wrote:
Hi Vijay,
Thank you very much for digging into this. A few comments below.
On 8/15/2022 4:39 PM, Jarkko Sakkinen wrote:
...
@@ -25,6 +25,8 @@ static const uint64_t MAGIC = 0x1122334455667788ULL; static const uint64_t MAGIC2 = 0x8877665544332211ULL; vdso_sgx_enter_enclave_t vdso_sgx_enter_enclave;
+static const unsigned long edmm_size = 8589934592; //8G
Could you please elaborate how this constant was chosen? I understand that this test helped to uncover a bug and it is useful to add to the kernel. When doing so this test will be run on systems with a variety of SGX memory sizes, could you please elaborate (and add a snippet) how 8GB is the right value for all systems?
It is the only constant I know for sure that some people (Vijay and Haitao) have been able to reproduce the bug.
Unless someone can show that the same bug reproduces with a smaller constant, changing it would make the whole test irrelevant.
I tried with 2GB and it always succeed and with 4GB was able to repro
sporadically. But with 8GB failure was consistent. One thing to note is even with 8GB Haitao couldn't reproduce this every time. So not sure if it good for all the systems but on my ICX system, I was able to consistently repro with this value.
Could all of this information be placed in a description of this constant? At this time it appears to be arbitrary.
Yes it makes sense to record the reason for this constant.
- if (!sgx2_supported())
SKIP(return, "SGX2 not supported");- ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self-
encl,
+_metadata));
- memset(&self->run, 0, sizeof(self->run));
- self->run.tcs = self->encl.encl_base;
- for (i = 0; i < self->encl.nr_segments; i++) {
struct encl_segment *seg = &self->encl.segment_tbl[i];total_size += seg->size;TH_LOG("test enclave: total_size = %ld, seg->size = %ld",total_size, seg->size);
- }
- /*
* Actual enclave size is expected to be larger than the loaded* test enclave since enclave size must be a power of 2 in bytes while* test_encl does not consume it all.*/- EXPECT_LT(total_size + edmm_size, self->encl.encl_size);
Will this test ever fail?
With a *quick* look: no.
Vijay, what was the point of this check?
Yes we can remove this check. I tried to copy from `augment_via_eaccept`
and just changed the request size.
In augment_via_eaccept the check is required since augment_via_eaccept assumes that there is enough address space in the existing enclave for dynamic memory addition without needing to change the enclave size. If anybody later changes the test enclave to break this assumption then that check will pick it up.
Got it, thanks. Yes this check is can be removed.
In this new test the enclave size is set to accommodate the planned dynamic memory addition and thus adding a test to check if the enclave has enough space for the dynamic memory is not needed.
- TH_LOG("Entering enclave to run EACCEPT for each page of %zd
bytes may take a while ...",
edmm_size);- eaccept_op.flags = SGX_SECINFO_R | SGX_SECINFO_W |
SGX_SECINFO_REG | SGX_SECINFO_PENDING;
- eaccept_op.ret = 0;
- eaccept_op.header.type = ENCL_OP_EACCEPT;
- for (i = 0; i < edmm_size; i += 4096) {
eaccept_op.epc_addr = (uint64_t)(addr + i);EXPECT_EQ(ENCL_CALL(&eaccept_op, &self->run, true), 0);if (self->run.exception_vector == 14 &&self->run.exception_error_code == 4 &&self->run.exception_addr == self->encl.encl_base) {munmap(addr, edmm_size);SKIP(return, "Kernel does not support adding pagesto initialized enclave");
}EXPECT_EQ(self->run.exception_vector, 0);EXPECT_EQ(self->run.exception_error_code, 0);EXPECT_EQ(self->run.exception_addr, 0);ASSERT_EQ(eaccept_op.ret, 0);ASSERT_EQ(self->run.function, EEXIT);- }
- /*
* New page should be accessible from within enclave - attempt to* write to it.*/This portion below was also copied from previous test and by only testing a write to the first page of the range the purpose is not clear. Could you please elaborate if the intention is to only test accessibility of the first page and why that is sufficient?
It is sufficient because the test reproduces the bug. It would have to be rather elaborated why you would possibly want to do more than
that.
That is fair. An accurate comment (currently an inaccurate copy&paste) would help to explain this part of the test.
- put_addr_op.value = MAGIC;
- put_addr_op.addr = (unsigned long)addr;
- put_addr_op.header.type = ENCL_OP_PUT_TO_ADDRESS;
- EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0);
- EXPECT_EEXIT(&self->run);
- EXPECT_EQ(self->run.exception_vector, 0);
- EXPECT_EQ(self->run.exception_error_code, 0);
- EXPECT_EQ(self->run.exception_addr, 0);
- /*
* Read memory from newly added page that was just written to,* confirming that data previously written (MAGIC) is present.*/- get_addr_op.value = 0;
- get_addr_op.addr = (unsigned long)addr;
- get_addr_op.header.type = ENCL_OP_GET_FROM_ADDRESS;
- EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0);
- EXPECT_EQ(get_addr_op.value, MAGIC);
- EXPECT_EEXIT(&self->run);
- EXPECT_EQ(self->run.exception_vector, 0);
- EXPECT_EQ(self->run.exception_error_code, 0);
- EXPECT_EQ(self->run.exception_addr, 0);
- munmap(addr, edmm_size);
+}
/*
- SGX2 page type modification test in two phases:
- Phase 1:
diff --git a/tools/testing/selftests/sgx/main.h b/tools/testing/selftests/sgx/main.h index fc585be97e2f..fe5d39ac0e1e 100644 --- a/tools/testing/selftests/sgx/main.h +++ b/tools/testing/selftests/sgx/main.h @@ -35,7 +35,8 @@ extern unsigned char sign_key[]; extern unsigned char sign_key_end[];
void encl_delete(struct encl *ctx); -bool encl_load(const char *path, struct encl *encl, unsigned long heap_size); +bool encl_load(const char *path, struct encl *encl, unsigned long
heap_size,
unsigned long edmm_size);bool encl_measure(struct encl *encl); bool encl_build(struct encl *encl); uint64_t encl_get_entry(struct encl *encl, const char *symbol); diff --git a/tools/testing/selftests/sgx/sigstruct.c b/tools/testing/selftests/sgx/sigstruct.c index 50c5ab1aa6fa..6000cf0e4975 100644 --- a/tools/testing/selftests/sgx/sigstruct.c +++ b/tools/testing/selftests/sgx/sigstruct.c @@ -343,7 +343,7 @@ bool encl_measure(struct encl *encl) if (!ctx) goto err;
- if (!mrenclave_ecreate(ctx, encl->src_size))
if (!mrenclave_ecreate(ctx, encl->encl_size)) goto err;
for (i = 0; i < encl->nr_segments; i++) {
Looking at mrenclave_ecreate() the above snippet seems separate from this test and incomplete since it now obtains encl->encl_size but continues to compute it again internally. Should this be a separate fix?
I would remove this part completely but this also needs comment from
Vijay.
If we restrict the large enclave size just for this test, then the above change
can be reverted. Calling ` mrenclave_ecreate` with src_size esults in EINIT failure and I think the reason is because of incorrect MRenclave.
From what I understand this change is needed since the enclave size is no longer just the size of all the segments at enclave creation. I think it is incomplete though since it still recomputes the enclave size even though it is now provided as parameter. This change does not need to be part of this test addition.
I see your point and this change can be removed from the test.
Reinette
Regards, Vijay