Date: Fri, 12 Dec 2014 00:04:53 +0100
From: "Marcel J.E. Mol" <marcel@mesa.nl>
To: Djalal Harouni <tixxdz@opendz.org>
Cc: akpm@linux-foundation.org, adobriyan@gmail.com, ebiederm@xmission.com,
        oleg@redhat.com, luto@amacapital.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Make /proc/<pid>/io world readable
Message-ID: <20141211230453.GB30907@joshua.mesa.nl>
References: <20141211162228.GA10717@rim.emol.mesa.nl> <20141211192911.GA3080@dztty>
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On Thu, Dec 11, 2014 at 08:29:11PM +0100, Djalal Harouni wrote:
> Hi,
> 
> On Thu, Dec 11, 2014 at 05:22:28PM +0100, Marcel Mol wrote:
> > /proc/<pid>/io is only readable by the pid owner, while files
> > like stat, statm and status are world readable.
> > I see no reason why io statistics should be hidden.
> > This patch makes io also world readable so process io counts
> > can be analysed without root permissions.
> As Andy noted this should be the other way around! so unless you have
> a real usecase, this will revert previous patch by Vasiliy that closed
> some info leaks...
> https://lkml.org/lkml/2011/7/27/459
> 
> Thanks!

Hi Djalal, thanks for pointing this out. I did look for info like this,
but did not look that far back. I can see the issues Vasiliy points out.

I do not have a real important usecase, but it is just convenience.
On my home (personal) workstation I trust noone is looking for my
password length in ssh or ftp, but I sometimes do like to see what
process is keeping my disk busy. And I want to limit switching to
root...

So I guess I'm more interested in the read_byte, write_bytes and
cancelled_write_bytes fields (Per physical disk or filesystem
preferably.)
Would that give away any sensitive information? 
If not maybe a separate /proc/PID/dio can be created to show only
these fields.

Thanks.
-Marcel

> 
> > Signed-off-by: Marcel Mol <marcel@mesa.nl>
> > ---
> >  fs/proc/base.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/proc/base.c b/fs/proc/base.c
> > index 772efa4..7bd8dbe 100644
> > --- a/fs/proc/base.c
> > +++ b/fs/proc/base.c
> > @@ -2563,7 +2563,7 @@ static const struct pid_entry tgid_base_stuff[] = {
> >  	REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
> >  #endif
> >  #ifdef CONFIG_TASK_IO_ACCOUNTING
> > -	ONE("io",	S_IRUSR, proc_tgid_io_accounting),
> > +	ONE("io",	S_IRUGO, proc_tgid_io_accounting),
> >  #endif
> >  #ifdef CONFIG_HARDWALL
> >  	ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
> > @@ -2904,7 +2904,7 @@ static const struct pid_entry tid_base_stuff[] = {
> >  	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
> >  #endif
> >  #ifdef CONFIG_TASK_IO_ACCOUNTING
> > -	ONE("io",	S_IRUSR, proc_tid_io_accounting),
> > +	ONE("io",	S_IRUGO, proc_tid_io_accounting),
> >  #endif
> >  #ifdef CONFIG_HARDWALL
> >  	ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
> > -- 
> > 1.9.3
> > 
> > 
> 
> -- 
> Djalal Harouni
> http://opendz.org
> --
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