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Date: Tue, 5 Apr 2022 18:16:41 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-sgx@...r.kernel.rog
Cc: Dave Hansen <dave.hansen@...ux.intel.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Nathaniel McCallum <nathaniel@...fian.com>,
Jarkko Sakkinen <jarkko@...nel.org>,
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-sgx@...r.kernel.org (open list:INTEL SGX),
linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
64-BIT))
Subject: [PATCH RFC] x86/sgx: Simplify struct sgx_enclave_restrict_permissions
The reasoning to change SECINFO to simply flags is stated in this inline
comment:
/*
* Return valid permission fields from a secinfo structure provided by
* user space. The secinfo structure is required to only have bits in
* the permission fields set.
*/
It is better to simply change the parameter type than require to use
a malformed version of a data structure.
Link: https://lore.kernel.org/linux-sgx/26ab773de8842d03b40caf8645ca86884b195901.camel@kernel.org/T/#u
Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
---
Only compile-tested.
arch/x86/include/uapi/asm/sgx.h | 5 ++-
arch/x86/kernel/cpu/sgx/ioctl.c | 57 ++++++---------------------------
2 files changed, 12 insertions(+), 50 deletions(-)
diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
index feda7f85b2ce..627136798f2a 100644
--- a/arch/x86/include/uapi/asm/sgx.h
+++ b/arch/x86/include/uapi/asm/sgx.h
@@ -88,15 +88,14 @@ struct sgx_enclave_provision {
* @offset: starting page offset (page aligned relative to enclave base
* address defined in SECS)
* @length: length of memory (multiple of the page size)
- * @secinfo: address for the SECINFO data containing the new permission bits
- * for pages in range described by @offset and @length
+ * @flags: flags field of the SECINFO data
* @result: (output) SGX result code of ENCLS[EMODPR] function
* @count: (output) bytes successfully changed (multiple of page size)
*/
struct sgx_enclave_restrict_permissions {
__u64 offset;
__u64 length;
- __u64 secinfo;
+ __u64 flags;
__u64 result;
__u64 count;
};
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index f88bc1236276..3c334e0bd4d9 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -676,41 +676,6 @@ static int sgx_ioc_sgx2_ready(struct sgx_encl *encl)
return 0;
}
-/*
- * Return valid permission fields from a secinfo structure provided by
- * user space. The secinfo structure is required to only have bits in
- * the permission fields set.
- */
-static int sgx_perm_from_user_secinfo(void __user *_secinfo, u64 *secinfo_perm)
-{
- struct sgx_secinfo secinfo;
- u64 perm;
-
- if (copy_from_user(&secinfo, (void __user *)_secinfo,
- sizeof(secinfo)))
- return -EFAULT;
-
- if (secinfo.flags & ~SGX_SECINFO_PERMISSION_MASK)
- return -EINVAL;
-
- if (memchr_inv(secinfo.reserved, 0, sizeof(secinfo.reserved)))
- return -EINVAL;
-
- perm = secinfo.flags & SGX_SECINFO_PERMISSION_MASK;
-
- /*
- * 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 (!(perm & SGX_SECINFO_R))
- return -EINVAL;
-
- *secinfo_perm = perm;
-
- return 0;
-}
-
/*
* Some SGX functions require that no cached linear-to-physical address
* mappings are present before they can succeed. Collaborate with
@@ -753,7 +718,6 @@ static int sgx_enclave_etrack(struct sgx_encl *encl)
* sgx_enclave_restrict_permissions() - Restrict EPCM permissions
* @encl: Enclave to which the pages belong.
* @modp: Checked parameters from user on which pages need modifying.
- * @secinfo_perm: New (validated) permission bits.
*
* Return:
* - 0: Success.
@@ -761,8 +725,7 @@ static int sgx_enclave_etrack(struct sgx_encl *encl)
*/
static long
sgx_enclave_restrict_permissions(struct sgx_encl *encl,
- struct sgx_enclave_restrict_permissions *modp,
- u64 secinfo_perm)
+ struct sgx_enclave_restrict_permissions *modp)
{
struct sgx_encl_page *entry;
struct sgx_secinfo secinfo;
@@ -772,7 +735,7 @@ sgx_enclave_restrict_permissions(struct sgx_encl *encl,
int ret;
memset(&secinfo, 0, sizeof(secinfo));
- secinfo.flags = secinfo_perm;
+ secinfo.flags = modp->flags;
for (c = 0 ; c < modp->length; c += PAGE_SIZE) {
addr = encl->base + modp->offset + c;
@@ -871,7 +834,6 @@ static long sgx_ioc_enclave_restrict_permissions(struct sgx_encl *encl,
void __user *arg)
{
struct sgx_enclave_restrict_permissions params;
- u64 secinfo_perm;
long ret;
ret = sgx_ioc_sgx2_ready(encl);
@@ -884,15 +846,16 @@ static long sgx_ioc_enclave_restrict_permissions(struct sgx_encl *encl,
if (sgx_validate_offset_length(encl, params.offset, params.length))
return -EINVAL;
- ret = sgx_perm_from_user_secinfo((void __user *)params.secinfo,
- &secinfo_perm);
- if (ret)
- return ret;
-
- if (params.result || params.count)
+ /*
+ * 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.flags & ~SGX_SECINFO_PERMISSION_MASK || !(params.flags & SGX_SECINFO_R) ||
+ params.result || params.count)
return -EINVAL;
- ret = sgx_enclave_restrict_permissions(encl, ¶ms, secinfo_perm);
+ ret = sgx_enclave_restrict_permissions(encl, ¶ms);
if (copy_to_user(arg, ¶ms, sizeof(params)))
return -EFAULT;
--
2.35.1
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