linux-kernel - [PATCH] x86/sgx: Allow RW for TCS pages

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Message-Id: <20220319163010.101686-1-jarkko@kernel.org>
Date:   Sat, 19 Mar 2022 18:30:10 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     linux-sgx@...r.kernel.org
Cc:     Jarkko Sakkinen <jarkko@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        "H. Peter Anvin" <hpa@...or.com>,
        linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
        64-BIT))
Subject: [PATCH] x86/sgx: Allow RW for TCS pages

Not allowing to set RW for added TCS pages leads only to a special case
to be handled in the user space run-time. Thus, allow permissions to be
set RW. Originally, it would have probably made more sense to check up
that the permissions are RW.

Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
---
 arch/x86/kernel/cpu/sgx/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 83df20e3e633..f79761ad0400 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -215,7 +215,7 @@ static int sgx_validate_secinfo(struct sgx_secinfo *secinfo)
 	 * CPU will silently overwrite the permissions as zero, which means
 	 * that we need to validate it ourselves.
 	 */
-	if (pt == SGX_SECINFO_TCS && perm)
+	if (pt == SGX_SECINFO_TCS && (perm != 0 || perm != (PROT_READ | PROT_WRITE)))
 		return -EINVAL;
 
 	if (secinfo->flags & SGX_SECINFO_RESERVED_MASK)
-- 
2.35.1