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Add support for dumping Go swissmaps (#3127)

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pull/3128/head
Jason An 6 months ago committed by GitHub
parent b2638a0986
commit a6cf06b8cf
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GPG Key ID: B5690EEEBB952194
2 changed files with 242 additions and 44 deletions
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283
pwndbg/aglib/godbg.py
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@ -40,7 +40,9 @@ indent_amount = pwndbg.config.add_param(
)
debug_color = theme.add_color_param(
"go-dump-debug", "blue", "color for 'go-dump' command's debug info when --debug is specified"
"go-dump-debug",
"blue",
"color for 'go-dump' command's debug info when --debug is specified",
)
@ -51,9 +53,15 @@ def word_size() -> int:
Values taken from https://github.com/golang/go/blob/20b79fd5775c39061d949569743912ad5e58b0e7/src/go/types/sizes.go#L233-L252
"""
return {"i386": 4, "x86-64": 8, "aarch64": 8, "arm": 4, "rv64": 8, "powerpc": 8, "sparc": 8}[
pwndbg.aglib.arch.name
]
return {
"i386": 4,
"x86-64": 8,
"aarch64": 8,
"arm": 4,
"rv64": 8,
"powerpc": 8,
"sparc": 8,
}[pwndbg.aglib.arch.name]
def _align(offset: int, n: int) -> int:
@ -91,6 +99,7 @@ def compute_named_offsets(fields: Iterable[Tuple[str, int, int]]) -> Dict[str, i
"""
offsets = compute_offsets([f[1:] for f in fields])
ret = dict(zip([f[0] for f in fields] + ["$size"], offsets))
ret["$align"] = max(f[2] for f in fields)
return ret
@ -165,6 +174,15 @@ class Type(ABC):
"""
pass
@abstractmethod
def align(self) -> int:
"""
Returns the alignment of a type in bytes.
Used for computing array and struct layouts.
"""
pass
@abstractmethod
def get_typename(self) -> str:
"""
@ -269,7 +287,8 @@ def get_go_version() -> Tuple[int, ...] | None:
if elf is None:
return None
buildinfo = next(
(cast(int, s["sh_addr"]) for s in elf.sections if s["x_name"] == ".go.buildinfo"), None
(cast(int, s["sh_addr"]) for s in elf.sections if s["x_name"] == ".go.buildinfo"),
None,
)
# again, could do linear search
if buildinfo is None:
@ -324,7 +343,8 @@ def _guess_moduledata_types() -> int | None:
elf = get_elf()
if elf is not None:
addr = next(
(cast(int, x["sh_addr"]) for x in elf.sections if x["x_name"] == ".rodata"), None
(cast(int, x["sh_addr"]) for x in elf.sections if x["x_name"] == ".rodata"),
None,
)
return addr
return None
@ -459,6 +479,11 @@ class BackrefType(Type):
f"Cannot get size of placeholder type {type(self).__name__}. Perhaps the type is ill-formed? (e.g. struct that contains itself without indirection)"
)
def align(self) -> int:
raise NotImplementedError(
f"Cannot get alignment of placeholder type {type(self).__name__}. Perhaps the type is ill-formed? (e.g. struct that contains itself without indirection)"
)
def get_typename(self) -> str:
if self.meta:
return f"runtime({self.meta.size}){self.meta.addr:#x}"
@ -566,7 +591,12 @@ def _inner_decode_runtime_type(
size = load(offsets["Size_"], word)
align = load(offsets["Align_"], 1)
meta = GoTypeMeta(
name, kind, addr, size=size, align=align, direct_iface=(kind_raw & (1 << 5)) != 0
name,
kind,
addr,
size=size,
align=align,
direct_iface=(kind_raw & (1 << 5)) != 0,
)
cache[addr] = (meta, BackrefType(meta, addr))
simple_name = kind.get_simple_name()
@ -602,7 +632,10 @@ def _inner_decode_runtime_type(
info.append(f"Argument {i}{suffix}:")
else:
info.append(f"Return value {i - in_count}:")
info += [f" Type name: {ty_meta.name}", f" Type addr: {ty_ptr:#x}"]
info += [
f" Type name: {ty_meta.name}",
f" Type addr: {ty_ptr:#x}",
]
return (meta, BasicType(meta, "funcptr", info))
elif kind == GoTypeKind.ARRAY:
elem_ty_ptr = load(offsets["$size"], word)
@ -616,7 +649,10 @@ def _inner_decode_runtime_type(
if methods_count == 0:
return (meta, BasicType(meta, "any"))
elif type_start is None:
return (meta, BasicType(meta, "interface", [f"Method count: {methods_count}"]))
return (
meta,
BasicType(meta, "interface", [f"Method count: {methods_count}"]),
)
else:
info = []
methods_ptr = load(offsets["$size"] + word, word)
@ -687,10 +723,9 @@ def _inner_decode_runtime_type(
field_ty = field_meta.name
fields.append((field_name, field_ty, field_off))
fields.sort(key=lambda f: f[2])
sz = load(offsets["Size_"], word)
return (
meta,
StructType(meta, fields, sz, None if name.startswith("struct ") else name),
StructType(meta, fields, size, align, None if name.startswith("struct ") else name),
)
else:
# currently channels and functions are unsupported
@ -718,6 +753,7 @@ class BasicType(Type):
name: str
sz: int = dataclasses.field(init=False)
algn: int = dataclasses.field(init=False)
extra_meta: List[str] = dataclasses.field(default_factory=list)
def dump(self, addr: int, fmt: FormatOpts = FormatOpts()) -> str:
@ -791,6 +827,9 @@ class BasicType(Type):
def size(self) -> int:
return self.sz
def align(self) -> int:
return self.algn
def get_typename(self) -> str:
return self.name
@ -801,20 +840,28 @@ class BasicType(Type):
ty = self.name
if ty in ("int8", "uint8", "bool", "byte"):
self.sz = 1
self.algn = 1
elif ty in ("int16", "uint16"):
self.sz = 2
self.algn = 2
elif ty in ("int32", "uint32", "float32", "rune"):
self.sz = 4
self.algn = 4
elif ty in ("int64", "uint64", "float64", "complex64"):
self.sz = 8
self.algn = 8
elif ty == "complex128":
self.sz = 16
self.algn = 8
elif ty in ("int", "uint", "uintptr", "funcptr"):
self.sz = word_size()
self.algn = word_size()
elif ty == "string":
self.sz = word_size() * 2
self.algn = word_size()
elif ty in ("any", "interface"):
self.sz = word_size() * 2
self.algn = word_size()
else:
raise ValueError(
f"Type {ty} is unknown. Use type hexdump[n] for an unknown type of size n."
@ -849,6 +896,9 @@ class SliceType(Type):
def size(self) -> int:
return word_size() * 3
def align(self) -> int:
return word_size()
def get_typename(self) -> str:
return f"[]{self.inner}"
@ -881,6 +931,9 @@ class PointerType(Type):
def size(self) -> int:
return word_size()
def align(self) -> int:
return word_size()
def get_typename(self) -> str:
return f"*{self.inner}"
@ -920,6 +973,9 @@ class ArrayType(Type):
def size(self) -> int:
return self.inner.size() * self.count
def align(self) -> int:
return self.inner.align()
def get_typename(self) -> str:
return f"[{self.count}]{self.inner}"
@ -941,29 +997,34 @@ class MapType(Type):
Note that maps in Go are actually pointers to the inner map,
but the map type printer here directly prints the inner map.
Maps don't have a simple layout, and may reasonably change,
but the last change was in 2017, so it probably won't.
The layout assumed is as follows (taken from src/runtime/map.go commit 1b4f1dc):
type hmap struct {
count int
flags uint8
B uint8
noverflow uint16
hash0 uint32
buckets unsafe.Pointer
oldbuckets unsafe.Pointer
nevacuate uintptr
extra *mapextra
}
Maps don't have a simple layout, and may reasonably change.
"""
key: Type
val: Type
@staticmethod
def field_offsets() -> Dict[str, int]:
def is_swiss() -> bool:
vers = get_go_version()
return vers is None or vers >= (1, 24)
@staticmethod
def field_offsets_noswiss() -> Dict[str, int]:
"""
The layout for pre-1.24 maps is as follows (taken from src/runtime/map.go commit 1b4f1dc):
type hmap struct {
count int
flags uint8
B uint8
noverflow uint16
hash0 uint32
buckets unsafe.Pointer
oldbuckets unsafe.Pointer
nevacuate uintptr
extra *mapextra
}
"""
word = word_size()
offsets = compute_named_offsets(
[
@ -980,10 +1041,92 @@ class MapType(Type):
)
return offsets
def dump(self, addr: int, fmt: FormatOpts = FormatOpts()) -> str:
@staticmethod
def field_offsets_swiss() -> Dict[str, int]:
"""
The layout for post-1.24 maps is as follows (taken from src/internal/runtime/map.go commit 4e63ae4):
type Map struct {
used uint64
seed uintptr
dirPtr unsafe.Pointer
dirLen int
globalDepth uint8
globalShift uint8
writing uint8
tombstonePossible bool
clearSeq uint64
}
"""
word = word_size()
offsets = compute_named_offsets(
[
("used", 8, 8), # uint64
("seed", word, word), # uintptr
("dirPtr", word, word), # unsafe.Pointer
("dirLen", word, word), # int
("globalDepth", 1, 1), # uint8
("globalShift", 1, 1), # uint8
("writing", 1, 1), # uint8
("tombstonePossible", 1, 1), # bool
("clearSeq", 8, 8), # uint64
]
)
return offsets
@staticmethod
def field_offsets_swiss_inner() -> Dict[str, int]:
"""
The layout for the inner swissmap is as follows (taken from src/internal/runtime/maps/table.go commit 4e63ae4):
type table struct {
used uint16
capacity uint16
growthLeft uint16
localDepth uint8
index int
groups groupsReference
}
"""
word = word_size()
offsets = compute_named_offsets(
[
("used", 2, 2), # uint16
("capacity", 2, 2), # uint16
("growthLeft", 2, 2), # uint16
("localDepth", 1, 1), # uint8
("index", word, word), # uint8
("groups", 16, 8), # groupsReference
]
)
return offsets
@classmethod
def field_offsets(cls) -> Dict[str, int]:
if cls.is_swiss():
return cls.field_offsets_swiss()
else:
return cls.field_offsets_noswiss()
@staticmethod
def format_entries(
entries: List[Tuple[int, int, str, str]], fmt: FormatOpts = FormatOpts()
) -> str:
# sort map by key, using integer comparison if possible
try:
entries.sort(key=lambda t: int(t[2], 0))
except ValueError:
entries.sort(key=lambda t: t[2])
formatted = []
for kp, vp, k, v in entries:
prefix = fmt.fmt_debug(f"(key @ {kp:#x}, val @ {vp:#x}) ")
formatted.append(f"{prefix}{k}: {v}")
return f"{{{fmt.fmt_elems(formatted)}}}"
def dump_noswiss(self, addr: int, fmt: FormatOpts = FormatOpts()) -> str:
bucket_count = 8 # taken from src/internal/abi/map.go commit 1b4f1dc
word = word_size()
offsets = self.field_offsets()
offsets = self.field_offsets_noswiss()
val = pwndbg.aglib.memory.read(addr, offsets["$size"])
load = lambda off, sz: load_uint(val[off : off + sz])
num_buckets = 1 << load(offsets["B"], 1)
@ -1020,20 +1163,61 @@ class MapType(Type):
v = self.val.dump(val_ptr, fmt)
ret.append((key_ptr, val_ptr, k, v))
bucket_ptr = load_uint(bucket[overflow_start : overflow_start + word])
# sort map by key, using integer comparison if possible
try:
ret.sort(key=lambda t: int(t[2], 0))
except ValueError:
ret.sort(key=lambda t: t[2])
formatted = []
for kp, vp, k, v in ret:
prefix = fmt.fmt_debug(f"(key @ {kp:#x}, val @ {vp:#x}) ")
formatted.append(f"{prefix}{k}: {v}")
return f"{{{fmt.fmt_elems(formatted)}}}"
return self.format_entries(ret, fmt)
def dump_swiss(self, addr: int, fmt: FormatOpts = FormatOpts()) -> str:
word = word_size()
offsets = self.field_offsets_swiss()
dir_ptr = load_uint(pwndbg.aglib.memory.read(addr + offsets["dirPtr"], word))
dir_len = load_uint(pwndbg.aglib.memory.read(addr + offsets["dirLen"], word))
slot_offsets = compute_named_offsets(
[
("key", self.key.size(), self.key.align()),
("elem", self.val.size(), self.val.align()),
]
)
group_offsets = compute_named_offsets(
[("ctrls", 8, 8), ("slots", slot_offsets["$size"] * 8, slot_offsets["$align"])]
)
if dir_len == 0:
groups = [dir_ptr]
else:
table_ptrs = pwndbg.aglib.memory.read(dir_ptr, word * dir_len)
tables = [load_uint(table_ptrs[i * word : i * word + word]) for i in range(dir_len)]
table_offsets = self.field_offsets_swiss_inner()
groups = []
for table in tables:
groups_ref = pwndbg.aglib.memory.read(table + table_offsets["groups"], 16)
group_base = load_uint(groups_ref[:word])
group_count = load_uint(groups_ref[8:]) + 1
for _ in range(group_count):
groups.append(group_base)
group_base += group_offsets["$size"]
ret = []
for group_base in groups:
group = pwndbg.aglib.memory.read(group_base, group_offsets["$size"])
for i in range(8):
if group[i] & 0x80 == 0:
off = 8 + slot_offsets["$size"] * i
key_ptr = group_base + off + slot_offsets["key"]
val_ptr = group_base + off + slot_offsets["elem"]
k = self.key.dump(key_ptr, fmt)
v = self.val.dump(val_ptr, fmt)
ret.append((key_ptr, val_ptr, k, v))
return self.format_entries(ret, fmt)
def dump(self, addr: int, fmt: FormatOpts = FormatOpts()) -> str:
if self.is_swiss():
return self.dump_swiss(addr, fmt)
else:
return self.dump_noswiss(addr, fmt)
def size(self) -> int:
return self.field_offsets()["$size"]
def align(self) -> int:
return 8
def get_typename(self) -> str:
return f"map[{self.key}]{self.val}"
@ -1062,6 +1246,7 @@ class StructType(Type):
fields: List[Tuple[str, Type | str, int]]
sz: int
algn: int | None = None
name: str | None = None
def dump(self, addr: int, fmt: FormatOpts = FormatOpts()) -> str:
@ -1079,6 +1264,11 @@ class StructType(Type):
def size(self) -> int:
return self.sz
def align(self) -> int:
if self.algn is None:
return max(ty.align() for (_, ty, _) in self.fields if isinstance(ty, Type))
return self.algn
def get_typename(self) -> str:
body = ";".join(
f"{off}:{name}:{ty}" for (name, ty, off) in self.fields if not isinstance(ty, str)
@ -1089,7 +1279,11 @@ class StructType(Type):
ret = []
for name, ty, off in self.fields:
if isinstance(ty, str) or not ty.meta:
ret += [f"Field {name}:", f" Offset: {off} ({off:#x})", f" Type: {ty}"]
ret += [
f"Field {name}:",
f" Offset: {off} ({off:#x})",
f" Type: {ty}",
]
else:
ret += [
f"Field {name}:",
@ -1112,6 +1306,7 @@ class RuntimeType(Type):
sz: int
addr: int
algn: int | None = dataclasses.field(init=False, default=None)
def dump(self, addr: int, fmt: FormatOpts = FormatOpts()) -> str:
(meta, ty) = decode_runtime_type(self.addr)
@ -1123,6 +1318,12 @@ class RuntimeType(Type):
def size(self) -> int:
return self.sz
def align(self) -> int:
if self.algn is None:
(meta, _ty) = decode_runtime_type(self.addr)
self.algn = meta.align
return self.algn
def get_typename(self) -> str:
return f"runtime({self.sz}){self.addr:#x}"

3
tests/library/gdb/tests/test_go.py
Unescape View File

@ -1,7 +1,6 @@
from __future__ import annotations
import gdb
import pytest
import tests
@ -49,11 +48,9 @@ def helper_test_dump(start_binary, filename):
assert third.strip() == """([3]complex64) [(1.1 + 2.2i), (-2.5 - 5.0i), (4.2 - 2.1i)]"""
@pytest.mark.skip(reason="TODO/FIXME: Needs fix for Go 1.24")
def test_go_dumping_x64(start_binary):
helper_test_dump(start_binary, GOSAMPLE_X64)
@pytest.mark.skip(reason="TODO/FIXME: Needs fix for Go 1.24")
def test_go_dumping_x86(start_binary):
helper_test_dump(start_binary, GOSAMPLE_X86)

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