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