MSVSphere Packaging Team
2 months ago
parent
0fb1c2c93b
commit
b27911f530
GPG Key ID:
B2B0B9F29E528FE8
@ -0,0 +1,245 @@
|
||||
From 4eaf4891c12589e3c7bdad5f5b076e4c8392dd06 Mon Sep 17 00:00:00 2001
|
||||
From: "Miss Islington (bot)"
|
||||
<31488909+miss-islington@users.noreply.github.com>
|
||||
Date: Sun, 1 Sep 2024 00:35:24 +0200
|
||||
Subject: [PATCH] [3.12] gh-121285: Remove backtracking when parsing tarfile
|
||||
headers (GH-121286) (GH-123543)
|
||||
|
||||
gh-121285: Remove backtracking when parsing tarfile headers (GH-121286)
|
||||
|
||||
* Remove backtracking when parsing tarfile headers
|
||||
* Rewrite PAX header parsing to be stricter
|
||||
* Optimize parsing of GNU extended sparse headers v0.0
|
||||
|
||||
(cherry picked from commit 34ddb64d088dd7ccc321f6103d23153256caa5d4)
|
||||
|
||||
Co-authored-by: Seth Michael Larson <seth@python.org>
|
||||
Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>
|
||||
Co-authored-by: Gregory P. Smith <greg@krypto.org>
|
||||
---
|
||||
Lib/tarfile.py | 103 ++++++++++++------
|
||||
Lib/test/test_tarfile.py | 42 +++++++
|
||||
...-07-02-13-39-20.gh-issue-121285.hrl-yI.rst | 2 +
|
||||
3 files changed, 112 insertions(+), 35 deletions(-)
|
||||
create mode 100644 Misc/NEWS.d/next/Security/2024-07-02-13-39-20.gh-issue-121285.hrl-yI.rst
|
||||
|
||||
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
|
||||
index e1487e3864d44b..0a0f31eca06c04 100755
|
||||
--- a/Lib/tarfile.py
|
||||
+++ b/Lib/tarfile.py
|
||||
@@ -843,6 +843,9 @@ def data_filter(member, dest_path):
|
||||
# Sentinel for replace() defaults, meaning "don't change the attribute"
|
||||
_KEEP = object()
|
||||
|
||||
+# Header length is digits followed by a space.
|
||||
+_header_length_prefix_re = re.compile(br"([0-9]{1,20}) ")
|
||||
+
|
||||
class TarInfo(object):
|
||||
"""Informational class which holds the details about an
|
||||
archive member given by a tar header block.
|
||||
@@ -1412,37 +1415,59 @@ def _proc_pax(self, tarfile):
|
||||
else:
|
||||
pax_headers = tarfile.pax_headers.copy()
|
||||
|
||||
- # Check if the pax header contains a hdrcharset field. This tells us
|
||||
- # the encoding of the path, linkpath, uname and gname fields. Normally,
|
||||
- # these fields are UTF-8 encoded but since POSIX.1-2008 tar
|
||||
- # implementations are allowed to store them as raw binary strings if
|
||||
- # the translation to UTF-8 fails.
|
||||
- match = re.search(br"\d+ hdrcharset=([^\n]+)\n", buf)
|
||||
- if match is not None:
|
||||
- pax_headers["hdrcharset"] = match.group(1).decode("utf-8")
|
||||
-
|
||||
- # For the time being, we don't care about anything other than "BINARY".
|
||||
- # The only other value that is currently allowed by the standard is
|
||||
- # "ISO-IR 10646 2000 UTF-8" in other words UTF-8.
|
||||
- hdrcharset = pax_headers.get("hdrcharset")
|
||||
- if hdrcharset == "BINARY":
|
||||
- encoding = tarfile.encoding
|
||||
- else:
|
||||
- encoding = "utf-8"
|
||||
-
|
||||
# Parse pax header information. A record looks like that:
|
||||
# "%d %s=%s\n" % (length, keyword, value). length is the size
|
||||
# of the complete record including the length field itself and
|
||||
- # the newline. keyword and value are both UTF-8 encoded strings.
|
||||
- regex = re.compile(br"(\d+) ([^=]+)=")
|
||||
+ # the newline.
|
||||
pos = 0
|
||||
- while match := regex.match(buf, pos):
|
||||
- length, keyword = match.groups()
|
||||
- length = int(length)
|
||||
- if length == 0:
|
||||
+ encoding = None
|
||||
+ raw_headers = []
|
||||
+ while len(buf) > pos and buf[pos] != 0x00:
|
||||
+ if not (match := _header_length_prefix_re.match(buf, pos)):
|
||||
+ raise InvalidHeaderError("invalid header")
|
||||
+ try:
|
||||
+ length = int(match.group(1))
|
||||
+ except ValueError:
|
||||
+ raise InvalidHeaderError("invalid header")
|
||||
+ # Headers must be at least 5 bytes, shortest being '5 x=\n'.
|
||||
+ # Value is allowed to be empty.
|
||||
+ if length < 5:
|
||||
+ raise InvalidHeaderError("invalid header")
|
||||
+ if pos + length > len(buf):
|
||||
+ raise InvalidHeaderError("invalid header")
|
||||
+
|
||||
+ header_value_end_offset = match.start(1) + length - 1 # Last byte of the header
|
||||
+ keyword_and_value = buf[match.end(1) + 1:header_value_end_offset]
|
||||
+ raw_keyword, equals, raw_value = keyword_and_value.partition(b"=")
|
||||
+
|
||||
+ # Check the framing of the header. The last character must be '\n' (0x0A)
|
||||
+ if not raw_keyword or equals != b"=" or buf[header_value_end_offset] != 0x0A:
|
||||
raise InvalidHeaderError("invalid header")
|
||||
- value = buf[match.end(2) + 1:match.start(1) + length - 1]
|
||||
+ raw_headers.append((length, raw_keyword, raw_value))
|
||||
+
|
||||
+ # Check if the pax header contains a hdrcharset field. This tells us
|
||||
+ # the encoding of the path, linkpath, uname and gname fields. Normally,
|
||||
+ # these fields are UTF-8 encoded but since POSIX.1-2008 tar
|
||||
+ # implementations are allowed to store them as raw binary strings if
|
||||
+ # the translation to UTF-8 fails. For the time being, we don't care about
|
||||
+ # anything other than "BINARY". The only other value that is currently
|
||||
+ # allowed by the standard is "ISO-IR 10646 2000 UTF-8" in other words UTF-8.
|
||||
+ # Note that we only follow the initial 'hdrcharset' setting to preserve
|
||||
+ # the initial behavior of the 'tarfile' module.
|
||||
+ if raw_keyword == b"hdrcharset" and encoding is None:
|
||||
+ if raw_value == b"BINARY":
|
||||
+ encoding = tarfile.encoding
|
||||
+ else: # This branch ensures only the first 'hdrcharset' header is used.
|
||||
+ encoding = "utf-8"
|
||||
|
||||
+ pos += length
|
||||
+
|
||||
+ # If no explicit hdrcharset is set, we use UTF-8 as a default.
|
||||
+ if encoding is None:
|
||||
+ encoding = "utf-8"
|
||||
+
|
||||
+ # After parsing the raw headers we can decode them to text.
|
||||
+ for length, raw_keyword, raw_value in raw_headers:
|
||||
# Normally, we could just use "utf-8" as the encoding and "strict"
|
||||
# as the error handler, but we better not take the risk. For
|
||||
# example, GNU tar <= 1.23 is known to store filenames it cannot
|
||||
@@ -1450,17 +1475,16 @@ def _proc_pax(self, tarfile):
|
||||
# hdrcharset=BINARY header).
|
||||
# We first try the strict standard encoding, and if that fails we
|
||||
# fall back on the user's encoding and error handler.
|
||||
- keyword = self._decode_pax_field(keyword, "utf-8", "utf-8",
|
||||
+ keyword = self._decode_pax_field(raw_keyword, "utf-8", "utf-8",
|
||||
tarfile.errors)
|
||||
if keyword in PAX_NAME_FIELDS:
|
||||
- value = self._decode_pax_field(value, encoding, tarfile.encoding,
|
||||
+ value = self._decode_pax_field(raw_value, encoding, tarfile.encoding,
|
||||
tarfile.errors)
|
||||
else:
|
||||
- value = self._decode_pax_field(value, "utf-8", "utf-8",
|
||||
+ value = self._decode_pax_field(raw_value, "utf-8", "utf-8",
|
||||
tarfile.errors)
|
||||
|
||||
pax_headers[keyword] = value
|
||||
- pos += length
|
||||
|
||||
# Fetch the next header.
|
||||
try:
|
||||
@@ -1475,7 +1499,7 @@ def _proc_pax(self, tarfile):
|
||||
|
||||
elif "GNU.sparse.size" in pax_headers:
|
||||
# GNU extended sparse format version 0.0.
|
||||
- self._proc_gnusparse_00(next, pax_headers, buf)
|
||||
+ self._proc_gnusparse_00(next, raw_headers)
|
||||
|
||||
elif pax_headers.get("GNU.sparse.major") == "1" and pax_headers.get("GNU.sparse.minor") == "0":
|
||||
# GNU extended sparse format version 1.0.
|
||||
@@ -1497,15 +1521,24 @@ def _proc_pax(self, tarfile):
|
||||
|
||||
return next
|
||||
|
||||
- def _proc_gnusparse_00(self, next, pax_headers, buf):
|
||||
+ def _proc_gnusparse_00(self, next, raw_headers):
|
||||
"""Process a GNU tar extended sparse header, version 0.0.
|
||||
"""
|
||||
offsets = []
|
||||
- for match in re.finditer(br"\d+ GNU.sparse.offset=(\d+)\n", buf):
|
||||
- offsets.append(int(match.group(1)))
|
||||
numbytes = []
|
||||
- for match in re.finditer(br"\d+ GNU.sparse.numbytes=(\d+)\n", buf):
|
||||
- numbytes.append(int(match.group(1)))
|
||||
+ for _, keyword, value in raw_headers:
|
||||
+ if keyword == b"GNU.sparse.offset":
|
||||
+ try:
|
||||
+ offsets.append(int(value.decode()))
|
||||
+ except ValueError:
|
||||
+ raise InvalidHeaderError("invalid header")
|
||||
+
|
||||
+ elif keyword == b"GNU.sparse.numbytes":
|
||||
+ try:
|
||||
+ numbytes.append(int(value.decode()))
|
||||
+ except ValueError:
|
||||
+ raise InvalidHeaderError("invalid header")
|
||||
+
|
||||
next.sparse = list(zip(offsets, numbytes))
|
||||
|
||||
def _proc_gnusparse_01(self, next, pax_headers):
|
||||
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
|
||||
index 3fbd25e742b181..e28d0311826e2b 100644
|
||||
--- a/Lib/test/test_tarfile.py
|
||||
+++ b/Lib/test/test_tarfile.py
|
||||
@@ -1237,6 +1237,48 @@ def test_pax_number_fields(self):
|
||||
finally:
|
||||
tar.close()
|
||||
|
||||
+ def test_pax_header_bad_formats(self):
|
||||
+ # The fields from the pax header have priority over the
|
||||
+ # TarInfo.
|
||||
+ pax_header_replacements = (
|
||||
+ b" foo=bar\n",
|
||||
+ b"0 \n",
|
||||
+ b"1 \n",
|
||||
+ b"2 \n",
|
||||
+ b"3 =\n",
|
||||
+ b"4 =a\n",
|
||||
+ b"1000000 foo=bar\n",
|
||||
+ b"0 foo=bar\n",
|
||||
+ b"-12 foo=bar\n",
|
||||
+ b"000000000000000000000000036 foo=bar\n",
|
||||
+ )
|
||||
+ pax_headers = {"foo": "bar"}
|
||||
+
|
||||
+ for replacement in pax_header_replacements:
|
||||
+ with self.subTest(header=replacement):
|
||||
+ tar = tarfile.open(tmpname, "w", format=tarfile.PAX_FORMAT,
|
||||
+ encoding="iso8859-1")
|
||||
+ try:
|
||||
+ t = tarfile.TarInfo()
|
||||
+ t.name = "pax" # non-ASCII
|
||||
+ t.uid = 1
|
||||
+ t.pax_headers = pax_headers
|
||||
+ tar.addfile(t)
|
||||
+ finally:
|
||||
+ tar.close()
|
||||
+
|
||||
+ with open(tmpname, "rb") as f:
|
||||
+ data = f.read()
|
||||
+ self.assertIn(b"11 foo=bar\n", data)
|
||||
+ data = data.replace(b"11 foo=bar\n", replacement)
|
||||
+
|
||||
+ with open(tmpname, "wb") as f:
|
||||
+ f.truncate()
|
||||
+ f.write(data)
|
||||
+
|
||||
+ with self.assertRaisesRegex(tarfile.ReadError, r"method tar: ReadError\('invalid header'\)"):
|
||||
+ tarfile.open(tmpname, encoding="iso8859-1")
|
||||
+
|
||||
|
||||
class WriteTestBase(TarTest):
|
||||
# Put all write tests in here that are supposed to be tested
|
||||
diff --git a/Misc/NEWS.d/next/Security/2024-07-02-13-39-20.gh-issue-121285.hrl-yI.rst b/Misc/NEWS.d/next/Security/2024-07-02-13-39-20.gh-issue-121285.hrl-yI.rst
|
||||
new file mode 100644
|
||||
index 00000000000000..81f918bfe2b255
|
||||
--- /dev/null
|
||||
+++ b/Misc/NEWS.d/next/Security/2024-07-02-13-39-20.gh-issue-121285.hrl-yI.rst
|
||||
@@ -0,0 +1,2 @@
|
||||
+Remove backtracking from tarfile header parsing for ``hdrcharset``, PAX, and
|
||||
+GNU sparse headers.
|
||||
Loading…
Reference in new issue