Messages in this thread | | | Subject | Re: [PATCH 00/26] Fixing wait, exit, ptrace, exec, and CLONE_THREAD | From | Aleksa Sarai <> | Date | Wed, 7 Jun 2017 05:40:21 +1000 |
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> Another easy entry point is to see that a multi-threaded setuid won't > change the credentials on a zombie thread group leader. Which can allow > sending signals to a process that the credential change should forbid. > This is in violation of posix and the semantics we attempt to enforce in > linux.
I might be completely wrong on this point (and I haven't looked at the patches), but I was under the impression that multi-threaded set[ug]id was implemented in userspace (by glibc's nptl(7) library that uses RT signals internally to get each thread to update their credentials). And given that, I wouldn't be surprised (as a user) that zombie threads will have stale credentials (glibc isn't running in those threads anymore).
Am I mistaken in that belief?
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-- Aleksa Sarai Software Engineer (Containers) SUSE Linux GmbH https://www.cyphar.com/
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