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@@ -0,0 +1,117 @@
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+ From c3caa02fe5e48e02a2ff2c0f409317022b05d34f Mon Sep 17 00:00:00 2001
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+ From: Petr Viktorin <encukou@gmail.com>
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+ Date: Fri, 3 Jun 2022 11:43:35 +0200
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+ Subject: [PATCH] 00382: CVE-2015-20107
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+
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+ Make mailcap refuse to match unsafe filenames/types/params (GH-91993)
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+
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+ Upstream: https://github.com/python/cpython/issues/68966
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+
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+ Tracker bug: https://bugzilla.redhat.com/show_bug.cgi?id=2075390
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+ ---
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+ lib-python/3/mailcap.py | 26 ++++++++++++++++++++++++--
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+ lib-python/3/test/test_mailcap.py | 8 ++++++--
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+ 2 files changed, 30 insertions(+), 4 deletions(-)
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+
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+ diff --git a/lib-python/3/mailcap.py b/lib-python/3/mailcap.py
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+ index ae416a8..444c640 100644
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+ --- a/lib-python/3/mailcap.py
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+ +++ b/lib-python/3/mailcap.py
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+ @@ -2,6 +2,7 @@
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+
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+ import os
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+ import warnings
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+ +import re
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+
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+ __all__ = ["getcaps","findmatch"]
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+
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+ @@ -13,6 +14,11 @@ def lineno_sort_key(entry):
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+ else:
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+ return 1, 0
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+
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+ +_find_unsafe = re.compile(r'[^\xa1-\U0010FFFF\w@+=:,./-]').search
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+ +
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+ +class UnsafeMailcapInput(Warning):
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+ + """Warning raised when refusing unsafe input"""
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+ +
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+
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+ # Part 1: top-level interface.
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+
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+ @@ -165,15 +171,22 @@ def findmatch(caps, MIMEtype, key='view', filename="/dev/null", plist=[]):
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+ entry to use.
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+
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+ """
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+ + if _find_unsafe(filename):
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+ + msg = "Refusing to use mailcap with filename %r. Use a safe temporary filename." % (filename,)
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+ + warnings.warn(msg, UnsafeMailcapInput)
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+ + return None, None
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+ entries = lookup(caps, MIMEtype, key)
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+ # XXX This code should somehow check for the needsterminal flag.
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+ for e in entries:
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+ if 'test' in e:
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+ test = subst(e['test'], filename, plist)
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+ + if test is None:
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+ + continue
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+ if test and os.system(test) != 0:
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+ continue
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+ command = subst(e[key], MIMEtype, filename, plist)
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+ - return command, e
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+ + if command is not None:
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+ + return command, e
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+ return None, None
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+
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+ def lookup(caps, MIMEtype, key=None):
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+ @@ -206,6 +219,10 @@ def subst(field, MIMEtype, filename, plist=[]):
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+ elif c == 's':
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+ res = res + filename
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+ elif c == 't':
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+ + if _find_unsafe(MIMEtype):
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+ + msg = "Refusing to substitute MIME type %r into a shell command." % (MIMEtype,)
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+ + warnings.warn(msg, UnsafeMailcapInput)
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+ + return None
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+ res = res + MIMEtype
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+ elif c == '{':
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+ start = i
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+ @@ -213,7 +230,12 @@ def subst(field, MIMEtype, filename, plist=[]):
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+ i = i+1
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+ name = field[start:i]
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+ i = i+1
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+ - res = res + findparam(name, plist)
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+ + param = findparam(name, plist)
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+ + if _find_unsafe(param):
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+ + msg = "Refusing to substitute parameter %r (%s) into a shell command" % (param, name)
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+ + warnings.warn(msg, UnsafeMailcapInput)
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+ + return None
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+ + res = res + param
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+ # XXX To do:
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+ # %n == number of parts if type is multipart/*
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+ # %F == list of alternating type and filename for parts
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+ diff --git a/lib-python/3/test/test_mailcap.py b/lib-python/3/test/test_mailcap.py
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+ index c08423c..920283d 100644
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+ --- a/lib-python/3/test/test_mailcap.py
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+ +++ b/lib-python/3/test/test_mailcap.py
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+ @@ -121,7 +121,8 @@ class HelperFunctionTest(unittest.TestCase):
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+ (["", "audio/*", "foo.txt"], ""),
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+ (["echo foo", "audio/*", "foo.txt"], "echo foo"),
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+ (["echo %s", "audio/*", "foo.txt"], "echo foo.txt"),
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+ - (["echo %t", "audio/*", "foo.txt"], "echo audio/*"),
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+ + (["echo %t", "audio/*", "foo.txt"], None),
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+ + (["echo %t", "audio/wav", "foo.txt"], "echo audio/wav"),
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+ (["echo \\%t", "audio/*", "foo.txt"], "echo %t"),
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+ (["echo foo", "audio/*", "foo.txt", plist], "echo foo"),
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+ (["echo %{total}", "audio/*", "foo.txt", plist], "echo 3")
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+ @@ -205,7 +206,10 @@ class FindmatchTest(unittest.TestCase):
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+ ('"An audio fragment"', audio_basic_entry)),
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+ ([c, "audio/*"],
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+ {"filename": fname},
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+ - ("/usr/local/bin/showaudio audio/*", audio_entry)),
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+ + (None, None)),
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+ + ([c, "audio/wav"],
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+ + {"filename": fname},
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+ + ("/usr/local/bin/showaudio audio/wav", audio_entry)),
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+ ([c, "message/external-body"],
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+ {"plist": plist},
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+ ("showexternal /dev/null default john python.org /tmp foo bar", message_entry))
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+ --
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+ 2.35.3
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+
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cstratak
commented 2 years ago
Fixes: rhbz#2075390