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SubjectRe: [PATCH V4 00/31] x86/sgx and selftests/sgx: Support SGX2
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Hi Vijay and Mark,

On 4/21/2022 4:46 PM, Dhanraj, Vijay wrote:
> Hi All,
>
> I evaluated V4 patch changes with Gramine and ran into an issue when trying to set EPC page permission to PROT_NONE. It looks like with V3 patch series a change was introduced which requires kernel to have at least R permission when calling RESTRICT IOCTL. This change was done under the assumption that EPCM requires at least R permission for EMODPE/EACCEPT to succeed. But when testing with V2 version, EACCEPT worked fine with page permission set to PROT_NONE.
>
> Thanks to @Shanahan, Mark for confirming that EPCM does not need to have R value to allow EACCEPT or EMODPE. Given this, can we please revert this change?
>

Thank you very much for pointing this out. I can revert the change
to what was done in V2 where the only check is to ensure that W requires R.
This is a requirement of EMODPR. Could you please check if this snippet
results in things working for you again?

---8<---
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 83674d054c13..7c7c8a61196e 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -855,12 +855,8 @@ static long sgx_ioc_enclave_restrict_permissions(struct sgx_encl *encl,
if (params.permissions & ~SGX_SECINFO_PERMISSION_MASK)
return -EINVAL;

- /*
- * Read access is required for the enclave to be able to use the page.
- * SGX instructions like ENCLU[EMODPE] and ENCLU[EACCEPT] require
- * read access.
- */
- if (!(params.permissions & SGX_SECINFO_R))
+ if ((params.permissions & SGX_SECINFO_W) &&
+ !(params.permissions & SGX_SECINFO_R))
return -EINVAL;

if (params.result || params.count)
--

Thank you very much

Reinette

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