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author | Guido van Rossum <guido@python.org> | 2002-08-08 19:46:52 +0000 |
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committer | Guido van Rossum <guido@python.org> | 2002-08-08 19:46:52 +0000 |
commit | 4272a02c05aa0c74dbf33c8359a476dc6c87ebf9 (patch) | |
tree | d0d8d8e0eb0370ef96c22feffe61942bdbd4d44a | |
parent | 354d0cb20141eced5ba4b9510be2aef104536018 (diff) | |
download | cpython-4272a02c05aa0c74dbf33c8359a476dc6c87ebf9.tar.gz |
Backport of SF patch 590294: os._execvpe security fix (Zack Weinberg).
1) Do not attempt to exec a file which does not exist
just to find out what error the operating system
returns. This is an exploitable race on all platforms
that support symbolic links.
2) Immediately re-raise the exception if we get an
error other than errno.ENOENT or errno.ENOTDIR. This
may need to be adapted for other platforms.
-rw-r--r-- | Lib/os.py | 27 |
1 files changed, 6 insertions, 21 deletions
@@ -301,8 +301,9 @@ def execvpe(file, args, env): __all__.extend(["execl","execle","execlp","execlpe","execvp","execvpe"]) -_notfound = None def _execvpe(file, args, env=None): + from errno import ENOENT, ENOTDIR + if env is not None: func = execve argrest = (args, env) @@ -310,7 +311,7 @@ def _execvpe(file, args, env=None): func = execv argrest = (args,) env = environ - global _notfound + head, tail = path.split(file) if head: apply(func, (file,) + argrest) @@ -320,30 +321,14 @@ def _execvpe(file, args, env=None): else: envpath = defpath PATH = envpath.split(pathsep) - if not _notfound: - if sys.platform[:4] == 'beos': - # Process handling (fork, wait) under BeOS (up to 5.0) - # doesn't interoperate reliably with the thread interlocking - # that happens during an import. The actual error we need - # is the same on BeOS for posix.open() et al., ENOENT. - try: unlink('/_#.# ## #.#') - except error, _notfound: pass - else: - import tempfile - t = tempfile.mktemp() - # Exec a file that is guaranteed not to exist - try: execv(t, ('blah',)) - except error, _notfound: pass - exc, arg = error, _notfound for dir in PATH: fullname = path.join(dir, file) try: apply(func, (fullname,) + argrest) except error, (errno, msg): - if errno != arg[0]: - exc, arg = error, (errno, msg) - raise exc, arg - + if errno != ENOENT and errno != ENOTDIR: + raise + raise error, (errno, msg) # Change environ to automatically call putenv() if it exists try: |