Re: New Security Features, Please Comment

[David Newall <davidn@davidnewall.com>]

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
information.