From: Tycho Andersen <tycho@tycho.ws>
To: "Tobin C. Harding" <me@tobin.cc>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>,
LKML <linux-kernel@vger.kernel.org>,
Alexander Kapshuk <alexander.kapshuk@gmail.com>
Subject: Re: [PATCH 1/3] leaking_addresses: skip all /proc/PID except /proc/1
Date: Thu, 1 Mar 2018 15:46:23 -0700 [thread overview]
Message-ID: <20180301224623.ehujx7gj26nu54ql@cisco> (raw)
In-Reply-To: <20180301210623.GA15198@eros>
On Fri, Mar 02, 2018 at 08:06:23AM +1100, Tobin C. Harding wrote:
> On Tue, Feb 27, 2018 at 03:45:09PM +1100, Tobin C. Harding wrote:
> > When the system is idle it is likely that most files under /proc/PID
> > will be identical for various processes. Scanning _all_ the PIDs under
> > /proc is unnecessary and implies that we are thoroughly scanning /proc.
> > This is _not_ the case because there may be ways userspace can trigger
> > creation of /proc files that leak addresses but were not present during
> > a scan. For these two reasons we should exclude all PID directories
> > under /proc except '1/'
> >
> > Exclude all /proc/PID except /proc/1.
> >
> > Signed-off-by: Tobin C. Harding <me@tobin.cc>
> > ---
> > scripts/leaking_addresses.pl | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl
> > index 6e5bc57caeaa..fb40e2828f43 100755
> > --- a/scripts/leaking_addresses.pl
> > +++ b/scripts/leaking_addresses.pl
> > @@ -10,6 +10,14 @@
> > # Use --debug to output path before parsing, this is useful to find files that
> > # cause the script to choke.
> >
> > +#
> > +# When the system is idle it is likely that most files under /proc/PID will be
> > +# identical for various processes. Scanning _all_ the PIDs under /proc is
> > +# unnecessary and implies that we are thoroughly scanning /proc. This is _not_
> > +# the case because there may be ways userspace can trigger creation of /proc
> > +# files that leak addresses but were not present during a scan. For these two
> > +# reasons we exclude all PID directories under /proc except '1/'
> > +
> > use warnings;
> > use strict;
> > use POSIX;
> > @@ -472,6 +480,9 @@ sub walk
> > my $path = "$pwd/$file";
> > next if (-l $path);
> >
> > + # skip /proc/PID except /proc/1
> > + next if ($path =~ /\/proc\/(?:[2-9][0-9]*|1[0-9]+)/);
>
> Perhaps the intent of this is clearer?
>
> next if (($path =~ /^\/proc\/[0-9]+$/) &&
> ($path !~ /^\/proc\/1$/));
+1, works for me.
Cheers,
Tycho
next prev parent reply other threads:[~2018-03-01 22:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-27 4:45 [PATCH 0/3] leaking_addresses: limit scan to PID==1 Tobin C. Harding
2018-02-27 4:45 ` [PATCH 1/3] leaking_addresses: skip all /proc/PID except /proc/1 Tobin C. Harding
2018-02-27 5:09 ` Tycho Andersen
2018-02-27 6:29 ` Tobin C. Harding
2018-02-27 7:15 ` Alexander Kapshuk
2018-02-27 21:06 ` Tobin C. Harding
2018-03-01 21:06 ` Tobin C. Harding
2018-03-01 22:46 ` Tycho Andersen [this message]
2018-03-03 9:44 ` Alexander Kapshuk
2018-02-27 4:45 ` [PATCH 2/3] leaking_addresses: skip '/proc/1/syscall' Tobin C. Harding
2018-02-27 4:45 ` [PATCH 3/3] leaking_addresses: remove version number Tobin C. Harding
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