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Reset inherited crash handlers before setting up the PAM helper so a module crash cannot relaunch the shell. Request a parent-death signal on Linux and FreeBSD, but treat setup as best effort: an unsupported or blocked call must not prevent password or fingerprint authentication. Check the parent PID after the request, in case the parent exited before the signal was configured.
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Crash/restart intentionally does not change PPID. Better approaches might be to
Then just unset the signal handlers from the parent process to get rid of crash handling in the subprocess. |
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PAM helpers can outlive the shell and keep the fingerprint reader busy until PAM times out. They also inherit the shell’s crash handler, so a PAM module crash can launch another shell.
Reset the helper’s crash handlers and request SIGKILL when its parent dies, with a PID check to cover the setup race. The signal request is best effort so a blocked or unsupported call won’t prevent authentication.
Both Linux reproductions fail on master and pass with this change: killing the shell stops the helper, and crashing the helper no longer relaunches the shell. Authentication also succeeds when the signal request returns EPERM. FreeBSD is untested.
Fixes #1249