[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <4EC2D568.4040001@xenotime.net>
Date: Tue, 15 Nov 2011 13:11:04 -0800
From: Randy Dunlap <rdunlap@...otime.net>
To: Vasiliy Kulikov <segoon@...nwall.com>
CC: kernel-hardening@...ts.openwall.com,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, Alexey Dobriyan <adobriyan@...il.com>,
Al Viro <viro@...iv.linux.org.uk>,
"H. Peter Anvin" <hpa@...or.com>, Greg KH <greg@...ah.com>,
Theodore Tso <tytso@....EDU>,
Alan Cox <alan@...rguk.ukuu.org.uk>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [RFC 3/3] procfs: add documentation for procfs mount options
On 11/15/2011 03:22 AM, Vasiliy Kulikov wrote:
> Signed-off-by: Vasiliy Kulikov <seooon@...nwall.com>
> --
> Documentation/filesystems/proc.txt | 39 ++++++++++++++++++++++++++++++++++++
> 1 files changed, 39 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
> index 0ec91f0..518987e 100644
> --- a/Documentation/filesystems/proc.txt
> +++ b/Documentation/filesystems/proc.txt
> @@ -1542,3 +1544,40 @@ a task to set its own or one of its thread siblings comm value. The comm value
> is limited in size compared to the cmdline value, so writing anything longer
> then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
> comm value.
> +
> +
> +------------------------------------------------------------------------------
> +Configuring procfs
> +------------------------------------------------------------------------------
> +
> +4.1 Mount options
> +---------------------
> +
> +The following mount options are supported:
> +
> + hidepid= Set /proc/<pid>/ access mode.
> + gid= Set the group authorized to learn processes information.
> +
> +hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
> +(default).
> +
> +hidepid=1 means users may not access any /proc/<pid>/ directories, but their
directories but their
(drop comma)
> +own. Sensitive files like cmdline, sched*, status are now protected against
> +other users. This makes impossible to learn whether any user runs
This makes it impossible
> +specific program (given the program doesn't reveal itself by its behaviour).
> +As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users,
> +poorly written programs passing sensitive information via program arguments are
> +now protected against local eavesdroppers.
> +
> +hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other
> +users. It doesn't mean that it hides a fact whether a process with a specific
> +pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"),
> +but it hides process' uid and gid, which may be learned by stat()'ing
> +/proc/<pid>/ otherwise. It greatly complicates intruder's task of gathering info
complicates an intruder's task of gathering information
(or data) [+ fix line length]
> +about running processes, whether some daemon runs with elevated privileges,
> +whether other user runs some sensitive program, whether other users run any
> +program at all, etc.
> +
> +gid= defines a group authorized to learn processes information otherwise
> +prohibited by hidepid=. If you use some daemon like identd which have to learn
which has to learn
or which must learn
or which needs to learn
> +information about processes information, just add identd to this group.
> --
--
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
