Re: New Security Features, Please Comment

From: David Newall
Date: Wed Dec 03 2008 - 01:54:42 EST

Geoffrey McRae wrote:
> Right now the only forseeable problem is that if a process holds a fd
> open when the parent app changes its uid/gid, which still, the worst
> that it can do is read/write another user's file.

Well, no, there are more problems than open file descriptors; and the
worst is much worse than reading or writing another user's file.
Suppose you're changing the ids of the Perl, Python or PHP interpreter:
the first user could install a SIGCLD handler and fork and exec sleep.
When sleep dies, the handler gets executed as another user - hopefully a
user with access to credit card details, or other financially valuable
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