From: Alexander Kapshuk <alexander.kapshuk@gmail.com>
To: "Tobin C. Harding" <me@tobin.cc>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>,
Tycho Andersen <tycho@tycho.ws>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] leaking_addresses: skip all /proc/PID except /proc/1
Date: Sat, 3 Mar 2018 11:44:26 +0200 [thread overview]
Message-ID: <CAJ1xhMWzxX=uuf4S6=augqSgSoh7ATUd=OMotgq3RgMHd13o_A@mail.gmail.com> (raw)
In-Reply-To: <20180301210623.GA15198@eros>
On Thu, Mar 1, 2018 at 11:06 PM, Tobin C. Harding <me@tobin.cc> 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 (($path =~ /^\/proc\/[0-9]+$/) &&
> ($path !~ /^\/proc\/1$/));
>
>
> thanks,
> Tobin.
Hi Tobin,
The intent is crystal clear now. Thanks.
Here's something that generates the same output as the code above:
next if ($path !~ "^/proc/(1|[^0-9]+)\$");
I'm not insisting this be given any preference whatsoever.
Thanks.
next prev parent reply other threads:[~2018-03-03 9:44 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
2018-03-03 9:44 ` Alexander Kapshuk [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAJ1xhMWzxX=uuf4S6=augqSgSoh7ATUd=OMotgq3RgMHd13o_A@mail.gmail.com' \
--to=alexander.kapshuk@gmail.com \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-kernel@vger.kernel.org \
--cc=me@tobin.cc \
--cc=tycho@tycho.ws \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).