diff options
| author | Oliver Smith-Denny <osde@microsoft.com> | 2025-01-29 11:05:03 -0800 |
|---|---|---|
| committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2025-02-07 02:23:11 +0000 |
| commit | e6b6aa90d490c298da140bc118d73ceff510f563 (patch) | |
| tree | e20b3795b7d5bab5c7280396aafbfb61e9b1b577 /MdePkg/Library/DynamicStackCookieEntryPointLib/X64/DynamicCookieMsvc.nasm | |
| parent | efbf5ed08c48478b51bb6b6da5670b1312755854 (diff) | |
| download | edk2-e6b6aa90d490c298da140bc118d73ceff510f563.tar.gz | |
MdePkg: Add Dynamic Stack Cookie Support
Adds dynamic stack cookies in the form of copies of the entry
point libraries that use shared logic to update stack cookies
at runtime.
This relies on RDRAND on IA32/X64 and RNDR on AARCH64 to get a
random number to apply to the stack cookie on module entry point.
This simplifies the logic a platform must do to include stack
check functionality.
Signed-off-by: Oliver Smith-Denny <osde@microsoft.com>
Diffstat (limited to 'MdePkg/Library/DynamicStackCookieEntryPointLib/X64/DynamicCookieMsvc.nasm')
| -rw-r--r-- | MdePkg/Library/DynamicStackCookieEntryPointLib/X64/DynamicCookieMsvc.nasm | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/MdePkg/Library/DynamicStackCookieEntryPointLib/X64/DynamicCookieMsvc.nasm b/MdePkg/Library/DynamicStackCookieEntryPointLib/X64/DynamicCookieMsvc.nasm new file mode 100644 index 0000000000..23c34e7289 --- /dev/null +++ b/MdePkg/Library/DynamicStackCookieEntryPointLib/X64/DynamicCookieMsvc.nasm @@ -0,0 +1,63 @@ +;------------------------------------------------------------------------------
+;
+; Copyright (c) Microsoft Corporation.
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+; DynamicCookie.nasm
+;
+; Abstract:
+;
+; Generates random number through CPU RdRand instruction on 64-bit platform
+; to store a random value in the GCC __stack_check_guard stack cookie.
+; The first byte is 0'd to prevent string copy functions from clobbering
+; the stack cookie.
+;
+; Notes:
+;
+; If RdRand fails, the build time static stack cookie value will be used instead.
+;
+;------------------------------------------------------------------------------
+
+DEFAULT REL
+SECTION .text
+
+extern ASM_PFX(__security_cookie)
+extern ASM_PFX(_CModuleEntryPoint)
+
+;------------------------------------------------------------------------------
+; VOID
+; EFIAPI
+; _ModuleEntryPoint (
+; Parameters are passed through. TODO: Make sure there are only two args on X64
+; );
+;------------------------------------------------------------------------------
+global ASM_PFX(_ModuleEntryPoint)
+ASM_PFX(_ModuleEntryPoint):
+ push rbx
+ push rcx
+ push rdx
+
+ mov eax, 1 ; Set eax to 1 to get feature information
+ cpuid ; Call cpuid
+ test ecx, 0x40000000 ; Test the rdrand bit (bit 30) in ecx
+ jz c_entry ; If rdrand is not supported, jump to c_entry
+
+ rdrand rax ; Call rdrand functionality here, getting a 64 bit value as on
+ ; X64, __stack_chk_guard is a 64 bit value.
+ ; CF=1 if RN generated ok, otherwise CF=0
+ jnc c_entry ; If the cmd fails, don't, update __stack_chk_guard, we'll have to move forward
+ ; with the static value provided at build time.
+
+ lea rbx, [rel ASM_PFX(__security_cookie)] ; load the address of __stack_check_guard into rbx
+
+ xor ah, ah ; Zero a byte of the __stack_chk_guard value to protect against string functions
+ ; (such as strcpy like functions) clobbering past the canary
+ mov [rbx], rax ; Store our random value, with 0'd first byte to __stack_chk_guard
+
+c_entry:
+ pop rdx
+ pop rcx
+ pop rbx
+ jmp ASM_PFX(_CModuleEntryPoint)
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