Fix insecure default temp file path in session dump/load#750
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eddieran wants to merge 1 commit intouqfoundation:masterfrom
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Fix insecure default temp file path in session dump/load#750eddieran wants to merge 1 commit intouqfoundation:masterfrom
eddieran wants to merge 1 commit intouqfoundation:masterfrom
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The default /tmp/session.pkl path is shared and world-writable, making it vulnerable to symlink attacks. This commit: - Adds _check_symlink() to reject symlinks before reading files - Adds _safe_open_for_writing() using O_CREAT|O_EXCL for race-free file creation with 0o600 permissions - Emits SecurityWarning when using the default shared temp path - Adds tests for symlink rejection and the security warning Closes #749 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
Fixes #749 — the default
/tmp/session.pklpath used bydump_module(),load_module(), andload_module_asdict()is insecure because/tmpis world-writable and shared, making it vulnerable to symlink attacks and race conditions.Changes
_check_symlink()that usesos.lstat()to reject symlinks before reading or writing session files._safe_open_for_writing()that usesos.open()withO_CREAT | O_EXCL | O_WRONLYand mode0o600for race-free exclusive file creation. If the file already exists, it verifies it is not a symlink before opening.SecurityWarningwhen the default shared/tmp/session.pklpath is used, advising users to pass an explicit filename.test_symlink_rejected()andtest_default_path_warning()totest_session.py.Files changed
dill/session.py— security helpers and warning indump_module,load_module,load_module_asdictdill/tests/test_session.py— new security testsTest plan
test_session.pytests passtest_symlink_rejectedverifies symlinks are rejected by all three functionstest_default_path_warningverifies SecurityWarning is emitted for the default path