Re: [PATCH 1/2] proc: restrict access to /proc/PID/io

[Balbir Singh]

On Fri, Jun 24, 2011 at 5:38 PM, Vasiliy Kulikov <segoon@xxxxxxxxxxxx> wrote:
> /proc/PID/io may be used for gathering private information.  E.g. for
> openssh and vsftpd daemons wchars/rchars may be used to learn the
> precise password length.  Restrict it to processes being able to ptrace
> the target process.
>

Hmm.. How do I reproduce this, won't they be enough randomness around
rchar/wchar by the time the attacker reads it?

> ptrace_may_access() is needed to prevent keeping open file descriptor of
> "io" file, executing setuid binary and gathering io information of the
> setuid'ed process.

Balbir Singh
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