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pwndbg/tests/qemu-tests/tests/system/test_commands_kernel.py

210 lines
8.0 KiB
Python

from __future__ import annotations
import random
import re
import gdb
import pytest
import pwndbg.aglib.kernel
import pwndbg.aglib.kernel.slab
import pwndbg.dbg
def test_command_kchecksec():
res = gdb.execute("kchecksec", to_string=True)
assert res != "" # for F841 warning
# TODO: do something with res
def test_command_kcmdline():
res = gdb.execute("kcmdline", to_string=True)
assert res != "" # for F841 warning
# TODO: do something with res
def test_command_kconfig():
res = gdb.execute("kconfig", to_string=True)
assert "CONFIG_IKCONFIG = y" in res
res = gdb.execute("kconfig IKCONFIG", to_string=True)
assert "CONFIG_IKCONFIG = y" in res
def test_command_kversion():
res = gdb.execute("kversion", to_string=True)
assert "Linux version" in res
def test_command_slab_list():
if not pwndbg.aglib.kernel.has_debug_syms():
res = gdb.execute("slab list", to_string=True)
assert "may only be run when debugging a Linux kernel with debug" in res
return
res = gdb.execute("slab list", to_string=True)
assert "kmalloc" in res
def test_command_slab_info():
if not pwndbg.aglib.kernel.has_debug_syms():
res = gdb.execute("slab info kmalloc-512", to_string=True)
assert "may only be run when debugging a Linux kernel with debug" in res
return
for cache in pwndbg.aglib.kernel.slab.caches():
cache_name = cache.name
res = gdb.execute(f"slab info -v {cache_name}", to_string=True)
assert cache_name in res
assert "Freelist" in res
for cpu in range(pwndbg.aglib.kernel.nproc()):
assert f"[CPU {cpu}]" in res
res = gdb.execute("slab info -v does_not_exit", to_string=True)
assert "not found" in res
def test_command_slab_contains():
if not pwndbg.aglib.kernel.has_debug_syms():
res = gdb.execute("slab contains 0x123", to_string=True)
assert "may only be run when debugging a Linux kernel with debug" in res
return
# retrieve a valid slab object address (first address from freelist)
addr, slab_cache = get_slab_object_address()
res = gdb.execute(f"slab contains {addr}", to_string=True)
assert f"{addr} @ {slab_cache}" in res
@pytest.mark.skipif(
pwndbg.aglib.arch.name not in ["i386", "x86-64"],
reason="function page_offset is only implemented for x86",
)
def test_x64_extra_registers_under_kernel_mode():
res = gdb.execute("context", to_string=True)
for reg in ["cr0", "cr3", "cr4", "fs_base", "gs_base", "efer", "ss", "cs"]:
assert reg.upper() in res
# those are the most important ones, and their presence should indicate it's working as intended
for flag in ["smep", "smap", "wp"]:
assert flag in res or flag.upper() in res
def get_slab_object_address():
"""helper function to get the address of some kmalloc slab object
and the associated slab cache name"""
caches = pwndbg.aglib.kernel.slab.caches()
for cache in caches:
cache_name = cache.name
info = gdb.execute(f"slab info -v {cache_name}", to_string=True)
ansi_escape = re.compile(r"\x1b\[[0-9;]*m")
info = ansi_escape.sub("", info)
matches = re.findall(r"- \[0x[0-9a-fA-F\-]{2}\] (0x[0-9a-fA-F]+)", info)
if len(matches) > 0:
return (matches[0], cache_name)
raise ValueError("Could not find any slab objects")
@pytest.mark.skipif(
pwndbg.aglib.arch.name not in ["i386", "x86-64"],
reason="Unsupported architecture: msr tests only work on x86 and x86-64",
)
def test_command_msr_read():
msr_lstar_literal = int(gdb.execute("msr MSR_LSTAR", to_string=True).split(":\t")[1], 16)
msr_lstar = int(gdb.execute("msr 0xc0000082", to_string=True).split(":\t")[1], 16)
assert msr_lstar == msr_lstar_literal
@pytest.mark.skipif(
pwndbg.aglib.arch.name not in ["i386", "x86-64"],
reason="Unsupported architecture: msr tests only work on x86 and x86-64",
)
def test_command_msr_write():
prev_msr_lstar = int(gdb.execute("msr MSR_LSTAR", to_string=True).split(":\t")[1], 16)
new_val = 0x4141414142424242
gdb.execute(f"msr MSR_LSTAR -w {new_val}")
new_msr_lstar = int(gdb.execute("msr 0xc0000082", to_string=True).split(":\t")[1], 16)
assert new_msr_lstar == new_val
gdb.execute(f"msr MSR_LSTAR -w {prev_msr_lstar}")
@pytest.mark.skipif(not pwndbg.aglib.kernel.has_debug_syms(), reason="test requires debug symbols")
@pytest.mark.skipif(
pwndbg.aglib.arch.name not in ["i386", "x86-64"],
reason="function page_offset is only implemented for x86",
)
def test_command_buddydump():
res = gdb.execute("buddydump", to_string=True)
NOFREEPAGE = "No free pages with specified filters found.\n"
if res == "WARNING: Symbol 'node_data' not found\n" or NOFREEPAGE == res:
return
# this indicates the buddy allocator contains at least one entry
assert "Order" in res and "Zone" in res and ("per_cpu_pageset" in res or "free_area" in res)
ansi_escape = re.compile(r"\x1b\[[0-9;]*m")
res = ansi_escape.sub("", res)
# find the starting addresses of all entries within the freelists
matches = re.findall(r"\[0x[0-9a-fA-F\-]{2}\] (0x[0-9a-fA-F]{16})", res)
for i in range(0, len(matches), 20):
# check every 20 elements so tests do not take too long
match = int(matches[i], 16)
res = gdb.execute(f"bud -f {hex(match + random.randint(0, 0x1000 - 1))}", to_string=True)
res = ansi_escape.sub("", res)
_matches = re.findall(r"\[0x[0-9a-fA-F\-]{2}\] (0x[0-9a-fA-F]{16})", res)
# asserting `bud -f` behaviour -- should be able to find the corresponding entry to an address
# even if the address is not aligned
assert len(_matches) == 1 and int(_matches[0], 16) == match
# nonexistent node index should not contain any entries
no_output = gdb.execute("buddydump -n 10", to_string=True)
assert NOFREEPAGE == no_output
# below checks are for filters
# for example, if a zone name is specified, other zones should not be present
filter_res = gdb.execute("bud -z DMA", to_string=True)
for name in ["DMA32", "Normal", "HighMem", "Movable", "Device"]:
assert f"Zone {name}" not in filter_res
filter_res = gdb.execute("bud -m Unmovable", to_string=True)
for name in ["Movable", "Reclaimable", "HighAtomic", "CMA", "Isolate"]:
assert f"- {name}" not in filter_res
filter_res = gdb.execute("bud -o 1", to_string=True)
for i in range(11):
if i == 1:
continue
assert f"Order {i}" not in filter_res
filter_res = gdb.execute("bud -p", to_string=True)
assert "free_area" not in filter_res
@pytest.mark.skipif(
pwndbg.aglib.arch.name not in ["i386", "x86-64"],
reason="pagewalk is only fully implemented for x86 (partially relies on cr3)",
)
def test_command_pagewalk():
address = pwndbg.aglib.kernel.kbase()
if address is None:
# no kbase? fine
pages = pwndbg.aglib.vmmap.get()
address = pages[0].start
if not pwndbg.aglib.kernel.has_debug_syms():
# even if no debug symbols, still gracefully handle it
res = gdb.execute(f"pagewalk {hex(address)}")
# now let's guess the phymap base and should work as intended
res = gdb.execute("set guess-physmap on")
res = gdb.execute(f"pagewalk {hex(address)}", to_string=True)
assert "PMD" in res # Page Size is only set for PMDe or PTe
res = res.splitlines()[-1]
match = re.findall(r"0x[0-9a-fA-F]{16}", res)[0]
physmap_addr = int(match, 16)
# compare the first 0x100 bytes of the page (e.g. first kernel image page) with its physmap conterpart
expected = pwndbg.aglib.memory.read(address, 0x100)
actual = pwndbg.aglib.memory.read(physmap_addr, 0x100)
assert all(expected[i] == actual[i] for i in range(0x100))
# make sure that when using cr3 for pgd, it still works
res2 = gdb.execute(f"pagewalk {hex(address)} --pgd $cr3", to_string=True).splitlines()[-1]
assert res == res2
# test non nonexistent address
res = gdb.execute("pagewalk 0", to_string=True)
assert res.splitlines()[-1] == "address is not mapped"