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Ring3: Enabled SMAP and SMEP.

This commit is contained in:
Mikhail Krichanov 2024-01-09 14:20:48 +03:00
parent 8c069a27e5
commit db69014ad8
4 changed files with 72 additions and 0 deletions
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20
MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
View File

@ -701,6 +701,10 @@ CreateIdentityMappingPageTables (
PAGE_TABLE_1G_ENTRY *PageDirectory1GEntry;
UINT64 AddressEncMask;
IA32_CR4 Cr4;
IA32_EFLAGS32 Eflags;
UINT32 Ebx;
Ebx = 0;
//
// Set PageMapLevel5Entry to suppress incorrect compiler/analyzer warnings
@ -970,5 +974,21 @@ CreateIdentityMappingPageTables (
EnableExecuteDisableBit ();
}
//
// Forbid supervisor-mode accesses to any user-mode pages.
// SMEP and SMAP must be supported.
//
AsmCpuidEx (0x07, 0x0, NULL, &Ebx, NULL, NULL);
if (((Ebx & BIT20) != 0) && ((Ebx & BIT7) != 0)) {
Cr4.UintN = AsmReadCr4 ();
Cr4.Bits.SMAP = 1;
Cr4.Bits.SMEP = 1;
AsmWriteCr4 (Cr4.UintN);
Eflags.UintN = AsmReadEflags ();
Eflags.Bits.AC = 0;
AsmWriteEflags (Eflags.UintN);
}
return (UINTN)PageMap;
}

18
MdePkg/Include/Library/BaseLib.h
View File

@ -6502,6 +6502,24 @@ AsmReadCr4 (
VOID
);
/**
Writes a value to the EFLAGS register.
Writes and returns a new value to the EFLAGS register. This function is
only available on IA-32 and x64. This writes a 32-bit value on IA-32 and
a 64-bit value on x64.
@param EFLAGS The value to write to EFLAGS.
@return The value written to EFLAGS.
**/
UINTN
EFIAPI
AsmWriteEflags (
UINTN Eflags
);
/**
Writes a value to Control Register 0 (CR0).

1
MdePkg/Library/BaseLib/BaseLib.inf
View File

@ -294,6 +294,7 @@
X64/ReadCr2.nasm| MSFT
X64/ReadCr0.nasm| MSFT
X64/ReadEflags.nasm| MSFT
X64/WriteEflags.nasm
X64/TdCall.nasm
X64/TdVmcall.nasm

33
MdePkg/Library/BaseLib/X64/WriteEflags.nasm Normal file
View File

@ -0,0 +1,33 @@
;------------------------------------------------------------------------------
;
; Copyright (c) 2024, Mikhail Krichanov. All rights reserved.
; SPDX-License-Identifier: BSD-3-Clause
;
; Module Name:
;
; WriteEflags.Asm
;
; Abstract:
;
; AsmWriteEflags function
;
; Notes:
;
;------------------------------------------------------------------------------
DEFAULT REL
SECTION .text
;------------------------------------------------------------------------------
; UINTN
; EFIAPI
; AsmWriteEflags (
; UINTN Eflags
; );
;------------------------------------------------------------------------------
global ASM_PFX(AsmWriteEflags)
ASM_PFX(AsmWriteEflags):
push rcx
popfq
mov rax, rcx
ret