Max Isbey
ec63c200fc
Bundled low-severity hardening:
- Lower DEFAULT_MAX_TEMPLATE_LENGTH from 1MB to 8KB. Real templates
are under 200 bytes; the old limit allowed 0.75s parse times.
- Replace max_expressions with max_variables (default 256). A single
{v0,v1,...,vN} expression packed arbitrarily many variables under
one expression count, bypassing the limit.
- Store UriTemplate internals as tuples. The dataclass is frozen but
list fields were mutable via t._parts.append(), violating the
immutability contract.
- Coerce ResourceSecurity.exempt_params to frozenset in __post_init__
so hash() works even when callers pass a regular set.
- Check drive letters against ASCII only. str.isalpha() is
Unicode-aware, so is_absolute_path("Ω:foo") falsely returned True.
156 lines
4.4 KiB
Python
156 lines
4.4 KiB
Python
"""Tests for filesystem path safety primitives."""
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from pathlib import Path
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import pytest
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from mcp.shared.path_security import (
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PathEscapeError,
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contains_path_traversal,
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is_absolute_path,
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safe_join,
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)
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@pytest.mark.parametrize(
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("value", "expected"),
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[
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# Safe: no traversal
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("a/b/c", False),
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("readme.txt", False),
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("", False),
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(".", False),
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("./a/b", False),
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# Safe: .. balanced by prior descent
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("a/../b", False),
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("a/b/../c", False),
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("a/b/../../c", False),
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# Unsafe: net escape
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("..", True),
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("../etc", True),
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("../../etc/passwd", True),
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("a/../../b", True),
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("./../../etc", True),
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# .. as substring, not component — safe
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("1.0..2.0", False),
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("foo..bar", False),
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("..foo", False),
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("foo..", False),
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# Backslash separator
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("..\\etc", True),
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("a\\..\\..\\b", True),
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("a\\b\\c", False),
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# Mixed separators
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("a/..\\..\\b", True),
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],
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)
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def test_contains_path_traversal(value: str, expected: bool):
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assert contains_path_traversal(value) is expected
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@pytest.mark.parametrize(
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("value", "expected"),
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[
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# Relative
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("relative/path", False),
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("file.txt", False),
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("", False),
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(".", False),
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("..", False),
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# POSIX absolute
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("/", True),
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("/etc/passwd", True),
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("/a", True),
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# Windows drive
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("C:", True),
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("C:\\Windows", True),
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("c:/foo", True),
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("Z:\\", True),
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# Windows UNC / backslash-absolute
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("\\\\server\\share", True),
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("\\foo", True),
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# Not a drive: digit before colon
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("1:foo", False),
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# Colon not in position 1
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("ab:c", False),
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# Non-ASCII letter is not a drive letter
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("Ω:namespace", False),
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("é:foo", False),
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],
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)
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def test_is_absolute_path(value: str, expected: bool):
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assert is_absolute_path(value) is expected
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def test_safe_join_simple(tmp_path: Path):
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result = safe_join(tmp_path, "docs", "readme.txt")
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assert result == tmp_path / "docs" / "readme.txt"
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def test_safe_join_resolves_relative_base(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
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monkeypatch.chdir(tmp_path)
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result = safe_join(".", "file.txt")
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assert result == tmp_path / "file.txt"
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def test_safe_join_rejects_dotdot_escape(tmp_path: Path):
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with pytest.raises(PathEscapeError, match="escapes base"):
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safe_join(tmp_path, "../../../etc/passwd")
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def test_safe_join_rejects_balanced_then_escape(tmp_path: Path):
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with pytest.raises(PathEscapeError, match="escapes base"):
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safe_join(tmp_path, "a/../../etc")
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def test_safe_join_allows_balanced_dotdot(tmp_path: Path):
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result = safe_join(tmp_path, "a/../b")
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assert result == tmp_path / "b"
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def test_safe_join_rejects_absolute_part(tmp_path: Path):
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with pytest.raises(PathEscapeError, match="is absolute"):
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safe_join(tmp_path, "/etc/passwd")
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def test_safe_join_rejects_absolute_in_later_part(tmp_path: Path):
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with pytest.raises(PathEscapeError, match="is absolute"):
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safe_join(tmp_path, "docs", "/etc/passwd")
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def test_safe_join_rejects_windows_drive(tmp_path: Path):
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with pytest.raises(PathEscapeError, match="is absolute"):
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safe_join(tmp_path, "C:\\Windows\\System32")
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def test_safe_join_rejects_null_byte(tmp_path: Path):
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with pytest.raises(PathEscapeError, match="null byte"):
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safe_join(tmp_path, "file\0.txt")
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def test_safe_join_rejects_null_byte_in_later_part(tmp_path: Path):
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with pytest.raises(PathEscapeError, match="null byte"):
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safe_join(tmp_path, "docs", "file\0.txt")
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def test_safe_join_rejects_symlink_escape(tmp_path: Path):
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outside = tmp_path / "outside"
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outside.mkdir()
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sandbox = tmp_path / "sandbox"
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sandbox.mkdir()
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(sandbox / "escape").symlink_to(outside)
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with pytest.raises(PathEscapeError, match="escapes base"):
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safe_join(sandbox, "escape", "secret.txt")
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def test_safe_join_base_equals_target(tmp_path: Path):
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# Joining nothing (or ".") should return the base itself
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assert safe_join(tmp_path) == tmp_path
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assert safe_join(tmp_path, ".") == tmp_path
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def test_path_escape_error_is_value_error():
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with pytest.raises(ValueError):
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safe_join("/tmp", "/etc")
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