ptrace allows you to read -r files

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Hello everyone,

While playing around I noticed that if I fork()ed, then did ptrace(PTRACE_TRACEME,...) then exec'd a non-readable binary, the ptrace interface would let me read the binary.

This was tested on 2.4.17ctx-5 (the security context patch), however I have been told it works on vanilla kernels, also I tested it on 2.4.2-pax on an old machine. (pentium 75...)

For those who want some demo code, you can find it at http://203.39.161.186/readbin.tgz.

For testing it, I used /usr/bin/ssh which was rws--x--x.

Since I'm not subscribed to this list, could any replies be cc'd to me? Thanks.

Sincerely,
Andrew Griffiths

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www.tasmail.com

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