Messages in this thread | | | Date | Tue, 28 Jun 2011 11:50:27 +0400 | From | Vasiliy Kulikov <> | Subject | Re: [PATCH 1/2] proc: restrict access to /proc/PID/io |
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On Tue, Jun 28, 2011 at 06:43 +0530, Balbir Singh wrote: > On Fri, Jun 24, 2011 at 5:38 PM, Vasiliy Kulikov <segoon@openwall.com> 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,
Just register taskstats listener and wait for "vsftpd" process. read_characters = strlen("USER username\r\n") + strlen("PASSWD pass\r\n") + 1.
> won't they be enough randomness around > rchar/wchar by the time the attacker reads it?
No, if you set "UsePrivilegeSeparation yes" in /etc/sshd/sshd_config or similar setting in vsftpd config (set by default), one process will have very small io activity, which is 100% related to the io in question.
http://www.openwall.com/lists/oss-security/2011/06/24/6
So, the total io = io with the network + io with privileged parent.
Thanks,
-- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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