linux-kernel - Re: [RFC 3/3] procfs: add documentation for procfs mount options

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<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 ***
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/