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[3.14] gh-135034: Normalize link targets in tarfile, add os.path.realpath(strict='allow_missing') (gh-135037) (gh-135065)

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Addresses CVEs 2024-12718, 2025-4138, 2025-4330, and 2025-4517.

(cherry picked from commit 3612d8f517)

Signed-off-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: Seth Michael Larson <seth@python.org>
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
This commit is contained in:
Łukasz Langa 2025-06-03 14:05:00 +02:00 • committed by GitHub
parent 78fd7ce3d2
commit 9e0ac76d96
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GPG key ID: B5690EEEBB952194
11 changed files with 970 additions and 173 deletions
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57
Lib/posixpath.py
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@ -36,7 +36,7 @@ __all__ = ["normcase","isabs","join","splitdrive","splitroot","split","splitext"
"samefile","sameopenfile","samestat",
"curdir","pardir","sep","pathsep","defpath","altsep","extsep",
"devnull","realpath","supports_unicode_filenames","relpath",
"commonpath", "isjunction","isdevdrive"]
"commonpath", "isjunction","isdevdrive","ALLOW_MISSING"]
def _get_sep(path):
@ -402,10 +402,18 @@ symbolic links encountered in the path."""
curdir = '.'
pardir = '..'
getcwd = os.getcwd
return _realpath(filename, strict, sep, curdir, pardir, getcwd)
if strict is ALLOW_MISSING:
ignored_error = FileNotFoundError
strict = True
elif strict:
ignored_error = ()
else:
ignored_error = OSError
lstat = os.lstat
readlink = os.readlink
maxlinks = None
def _realpath(filename, strict=False, sep=sep, curdir=curdir, pardir=pardir,
getcwd=os.getcwd, lstat=os.lstat, readlink=os.readlink, maxlinks=None):
# The stack of unresolved path parts. When popped, a special value of None
# indicates that a symlink target has been resolved, and that the original
# symlink path can be retrieved by popping again. The [::-1] slice is a
@ -477,27 +485,28 @@ def _realpath(filename, strict=False, sep=sep, curdir=curdir, pardir=pardir,
path = newpath
continue
target = readlink(newpath)
except OSError:
if strict:
raise
path = newpath
except ignored_error:
pass
else:
# Resolve the symbolic link
if target.startswith(sep):
# Symlink target is absolute; reset resolved path.
path = sep
if maxlinks is None:
# Mark this symlink as seen but not fully resolved.
seen[newpath] = None
# Push the symlink path onto the stack, and signal its specialness
# by also pushing None. When these entries are popped, we'll
# record the fully-resolved symlink target in the 'seen' mapping.
rest.append(newpath)
rest.append(None)
# Push the unresolved symlink target parts onto the stack.
target_parts = target.split(sep)[::-1]
rest.extend(target_parts)
part_count += len(target_parts)
continue
# Resolve the symbolic link
if target.startswith(sep):
# Symlink target is absolute; reset resolved path.
path = sep
if maxlinks is None:
# Mark this symlink as seen but not fully resolved.
seen[newpath] = None
# Push the symlink path onto the stack, and signal its specialness
# by also pushing None. When these entries are popped, we'll
# record the fully-resolved symlink target in the 'seen' mapping.
rest.append(newpath)
rest.append(None)
# Push the unresolved symlink target parts onto the stack.
target_parts = target.split(sep)[::-1]
rest.extend(target_parts)
part_count += len(target_parts)
# An error occurred and was ignored.
path = newpath
return path