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author | Thomas Kluyver <takowl@gmail.com> | 2014-01-23 15:09:51 -0800 |
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committer | Thomas Kluyver <takowl@gmail.com> | 2014-01-23 15:09:51 -0800 |
commit | bd999c1c3fe7ee5f30ede2cf704cf03e400347b4 (patch) | |
tree | 3716ae20aa80f1942cd34e48a7e8ef220fedd0f6 | |
parent | fc61714c67981945a9cd5632288558d229dabbef (diff) |
Improve security of get_runtime_dir(strict=False)
Fixes fd.o bug #73878.
-rw-r--r-- | xdg/BaseDirectory.py | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/xdg/BaseDirectory.py b/xdg/BaseDirectory.py index cececa3..a7c31b1 100644 --- a/xdg/BaseDirectory.py +++ b/xdg/BaseDirectory.py @@ -25,7 +25,7 @@ Typical usage: Note: see the rox.Options module for a higher-level API for managing options. """ -import os +import os, stat _home = os.path.expanduser('~') xdg_data_home = os.environ.get('XDG_DATA_HOME') or \ @@ -131,15 +131,30 @@ def get_runtime_dir(strict=True): import getpass fallback = '/tmp/pyxdg-runtime-dir-fallback-' + getpass.getuser() + create = False + try: - os.mkdir(fallback, 0o700) + # This must be a real directory, not a symlink, so attackers can't + # point it elsewhere. So we use lstat to check it. + st = os.lstat(fallback) except OSError as e: import errno - if e.errno == errno.EEXIST: - # Already exists - set 700 permissions again. - import stat - os.chmod(fallback, stat.S_IRUSR|stat.S_IWUSR|stat.S_IXUSR) - else: # pragma: no cover + if e.errno == errno.ENOENT: + create = True + else: raise - + else: + # The fallback must be a directory + if not stat.S_ISDIR(st.st_mode): + os.unlink(fallback) + create = True + # Must be owned by the user and not accessible by anyone else + elif (st.st_uid != os.getuid()) \ + or (st.st_mode & (stat.S_IRWXG | stat.S_IRWXO)): + os.rmdir(fallback) + create = True + + if create: + os.mkdir(fallback, 0o700) + return fallback |