| #!/usr/bin/env python3 |
| # SPDX-License-Identifier: GPL-2.0 |
| # |
| # Copyright (c) 2025 Intel Corporation |
| # |
| # Test for indirect target selection (ITS) mitigation. |
| # |
| # Test if indirect CALL/JMP are correctly patched by evaluating |
| # the vmlinux .retpoline_sites in /proc/kcore. |
| |
| # Install dependencies |
| # add-apt-repository ppa:michel-slm/kernel-utils |
| # apt update |
| # apt install -y python3-drgn python3-pyelftools python3-capstone |
| # |
| # Best to copy the vmlinux at a standard location: |
| # mkdir -p /usr/lib/debug/lib/modules/$(uname -r) |
| # cp $VMLINUX /usr/lib/debug/lib/modules/$(uname -r)/vmlinux |
| # |
| # Usage: ./its_indirect_alignment.py [vmlinux] |
| |
| import os, sys, argparse |
| from pathlib import Path |
| |
| this_dir = os.path.dirname(os.path.realpath(__file__)) |
| sys.path.insert(0, this_dir + '/../../kselftest') |
| import ksft |
| import common as c |
| |
| bug = "indirect_target_selection" |
| |
| mitigation = c.get_sysfs(bug) |
| if not mitigation or "Aligned branch/return thunks" not in mitigation: |
| ksft.test_result_skip("Skipping its_indirect_alignment.py: Aligned branch/return thunks not enabled") |
| ksft.finished() |
| |
| if c.sysfs_has("spectre_v2", "Retpolines"): |
| ksft.test_result_skip("Skipping its_indirect_alignment.py: Retpolines deployed") |
| ksft.finished() |
| |
| c.check_dependencies_or_skip(['drgn', 'elftools', 'capstone'], script_name="its_indirect_alignment.py") |
| |
| from elftools.elf.elffile import ELFFile |
| from drgn.helpers.common.memory import identify_address |
| |
| cap = c.init_capstone() |
| |
| if len(os.sys.argv) > 1: |
| arg_vmlinux = os.sys.argv[1] |
| if not os.path.exists(arg_vmlinux): |
| ksft.test_result_fail(f"its_indirect_alignment.py: vmlinux not found at argument path: {arg_vmlinux}") |
| ksft.exit_fail() |
| os.makedirs(f"/usr/lib/debug/lib/modules/{os.uname().release}", exist_ok=True) |
| os.system(f'cp {arg_vmlinux} /usr/lib/debug/lib/modules/$(uname -r)/vmlinux') |
| |
| vmlinux = f"/usr/lib/debug/lib/modules/{os.uname().release}/vmlinux" |
| if not os.path.exists(vmlinux): |
| ksft.test_result_fail(f"its_indirect_alignment.py: vmlinux not found at {vmlinux}") |
| ksft.exit_fail() |
| |
| ksft.print_msg(f"Using vmlinux: {vmlinux}") |
| |
| retpolines_start_vmlinux, retpolines_sec_offset, size = c.get_section_info(vmlinux, '.retpoline_sites') |
| ksft.print_msg(f"vmlinux: Section .retpoline_sites (0x{retpolines_start_vmlinux:x}) found at 0x{retpolines_sec_offset:x} with size 0x{size:x}") |
| |
| sites_offset = c.get_patch_sites(vmlinux, retpolines_sec_offset, size) |
| total_retpoline_tests = len(sites_offset) |
| ksft.print_msg(f"Found {total_retpoline_tests} retpoline sites") |
| |
| prog = c.get_runtime_kernel() |
| retpolines_start_kcore = prog.symbol('__retpoline_sites').address |
| ksft.print_msg(f'kcore: __retpoline_sites: 0x{retpolines_start_kcore:x}') |
| |
| x86_indirect_its_thunk_r15 = prog.symbol('__x86_indirect_its_thunk_r15').address |
| ksft.print_msg(f'kcore: __x86_indirect_its_thunk_r15: 0x{x86_indirect_its_thunk_r15:x}') |
| |
| tests_passed = 0 |
| tests_failed = 0 |
| tests_unknown = 0 |
| |
| with open(vmlinux, 'rb') as f: |
| elffile = ELFFile(f) |
| text_section = elffile.get_section_by_name('.text') |
| |
| for i in range(0, len(sites_offset)): |
| site = retpolines_start_kcore + sites_offset[i] |
| vmlinux_site = retpolines_start_vmlinux + sites_offset[i] |
| passed = unknown = failed = False |
| try: |
| vmlinux_insn = c.get_instruction_from_vmlinux(elffile, text_section, text_section['sh_addr'], vmlinux_site) |
| kcore_insn = list(cap.disasm(prog.read(site, 16), site))[0] |
| operand = kcore_insn.op_str |
| insn_end = site + kcore_insn.size - 1 # TODO handle Jcc.32 __x86_indirect_thunk_\reg |
| safe_site = insn_end & 0x20 |
| site_status = "" if safe_site else "(unsafe)" |
| |
| ksft.print_msg(f"\nSite {i}: {identify_address(prog, site)} <0x{site:x}> {site_status}") |
| ksft.print_msg(f"\tvmlinux: 0x{vmlinux_insn.address:x}:\t{vmlinux_insn.mnemonic}\t{vmlinux_insn.op_str}") |
| ksft.print_msg(f"\tkcore: 0x{kcore_insn.address:x}:\t{kcore_insn.mnemonic}\t{kcore_insn.op_str}") |
| |
| if (site & 0x20) ^ (insn_end & 0x20): |
| ksft.print_msg(f"\tSite at safe/unsafe boundary: {str(kcore_insn.bytes)} {kcore_insn.mnemonic} {operand}") |
| if safe_site: |
| tests_passed += 1 |
| passed = True |
| ksft.print_msg(f"\tPASSED: At safe address") |
| continue |
| |
| if operand.startswith('0xffffffff'): |
| thunk = int(operand, 16) |
| if thunk > x86_indirect_its_thunk_r15: |
| insn_at_thunk = list(cap.disasm(prog.read(thunk, 16), thunk))[0] |
| operand += ' -> ' + insn_at_thunk.mnemonic + ' ' + insn_at_thunk.op_str + ' <dynamic-thunk?>' |
| if 'jmp' in insn_at_thunk.mnemonic and thunk & 0x20: |
| ksft.print_msg(f"\tPASSED: Found {operand} at safe address") |
| passed = True |
| if not passed: |
| if kcore_insn.operands[0].type == capstone.CS_OP_IMM: |
| operand += ' <' + prog.symbol(int(operand, 16)) + '>' |
| if '__x86_indirect_its_thunk_' in operand: |
| ksft.print_msg(f"\tPASSED: Found {operand}") |
| else: |
| ksft.print_msg(f"\tPASSED: Found direct branch: {kcore_insn}, ITS thunk not required.") |
| passed = True |
| else: |
| unknown = True |
| if passed: |
| tests_passed += 1 |
| elif unknown: |
| ksft.print_msg(f"UNKNOWN: unexpected operand: {kcore_insn}") |
| tests_unknown += 1 |
| else: |
| ksft.print_msg(f'\t************* FAILED *************') |
| ksft.print_msg(f"\tFound {kcore_insn.bytes} {kcore_insn.mnemonic} {operand}") |
| ksft.print_msg(f'\t**********************************') |
| tests_failed += 1 |
| except Exception as e: |
| ksft.print_msg(f"UNKNOWN: An unexpected error occurred: {e}") |
| tests_unknown += 1 |
| |
| ksft.print_msg(f"\n\nSummary:") |
| ksft.print_msg(f"PASS: \t{tests_passed} \t/ {total_retpoline_tests}") |
| ksft.print_msg(f"FAIL: \t{tests_failed} \t/ {total_retpoline_tests}") |
| ksft.print_msg(f"UNKNOWN: \t{tests_unknown} \t/ {total_retpoline_tests}") |
| |
| if tests_failed == 0: |
| ksft.test_result_pass("All ITS return thunk sites passed") |
| else: |
| ksft.test_result_fail(f"{tests_failed} ITS return thunk sites failed") |
| ksft.finished() |
