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gh-128605: Add branch protections for x86_64 in asm_trampoline.S (#128606)

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Apply Intel Control-flow Technology for x86-64 on asm_trampoline.S.

Required for mitigation against return-oriented programming (ROP)
and Call or Jump Oriented Programming (COP/JOP) attacks.

Manual application is required for the assembly files.

See also: https://sourceware.org/annobin/annobin.html/Test-cf-protection.html
This commit is contained in:
stratakis 2025-06-03 09:09:43 +02:00 • committed by GitHub
parent 6e80f11eb5
commit 485b499610
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GPG key ID: B5690EEEBB952194
2 changed files with 26 additions and 0 deletions
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22
Python/asm_trampoline.S
View file

@ -9,6 +9,9 @@
# } # }
_Py_trampoline_func_start: _Py_trampoline_func_start:
#ifdef __x86_64__ #ifdef __x86_64__
#if defined(__CET__) && (__CET__ & 1)
endbr64
#endif
sub $8, %rsp sub $8, %rsp
call *%rcx call *%rcx
add $8, %rsp add $8, %rsp
@ -34,3 +37,22 @@ _Py_trampoline_func_start:
.globl _Py_trampoline_func_end .globl _Py_trampoline_func_end
_Py_trampoline_func_end: _Py_trampoline_func_end:
.section .note.GNU-stack,"",@progbits .section .note.GNU-stack,"",@progbits
# Note for indicating the assembly code supports CET
#if defined(__x86_64__) && defined(__CET__) && (__CET__ & 1)
.section .note.gnu.property,"a"
.align 8
.long 1f - 0f
.long 4f - 1f
.long 5
0:
.string "GNU"
1:
.align 8
.long 0xc0000002
.long 3f - 2f
2:
.long 0x3
3:
.align 8
4:
#endif // __x86_64__

4
Python/perf_jit_trampoline.c
View file

@ -869,7 +869,11 @@ static void elf_init_ehframe(ELFObjectContext* ctx) {
*/ */
#ifdef __x86_64__ #ifdef __x86_64__
/* x86_64 calling convention unwinding rules */ /* x86_64 calling convention unwinding rules */
# if defined(__CET__) && (__CET__ & 1)
DWRF_U8(DWRF_CFA_advance_loc | 8); // Advance location by 8 bytes when CET protection is enabled
# else
DWRF_U8(DWRF_CFA_advance_loc | 4); // Advance location by 4 bytes DWRF_U8(DWRF_CFA_advance_loc | 4); // Advance location by 4 bytes
# endif
DWRF_U8(DWRF_CFA_def_cfa_offset); // Redefine CFA offset DWRF_U8(DWRF_CFA_def_cfa_offset); // Redefine CFA offset
DWRF_UV(16); // New offset: SP + 16 DWRF_UV(16); // New offset: SP + 16
DWRF_U8(DWRF_CFA_advance_loc | 6); // Advance location by 6 bytes DWRF_U8(DWRF_CFA_advance_loc | 6); // Advance location by 6 bytes