linux-kernel - Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces

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] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 26 Jul 2016 12:11:02 -0700
From:	Andrew Vagin <avagin@...tuozzo.com>
To:	"W. Trevor King" <wking@...mily.us>
CC:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	Andrey Vagin <avagin@...nvz.org>,
	Linux API <linux-api@...r.kernel.org>,
	Linux Containers <containers@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"criu@...nvz.org" <criu@...nvz.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	"James Bottomley" <James.Bottomley@...senpartnership.com>,
	Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 0/5 RFC] Add an interface to discover relationships
 between namespaces

On Tue, Jul 26, 2016 at 11:32:25AM -0700, W. Trevor King wrote:
> On Tue, Jul 26, 2016 at 11:25:24AM -0700, Andrew Vagin wrote:
> > Sure. If a process wants to compare two namespaces, it needs to get file
> > descriptors for them (open /proc/PID/ns/XXX, use new ioctl-s, find a
> > process which has them),
> > and then it calls kcmp(pid1, pid2, KCMP_NSFD, ns_fd1, ns_fd2)
> 
> If you use the new ioctl-s to get ns_fd2, do you walk your local /proc
> to find pid2?

If you use the new ioctl-s to get nf_fd2, you will have it in the
current process, so pid2 will be getpid().

pidX identifies a process where to find fdX.

man 2 kcmp:
 The kcmp() system call can be used to check whether the  two processes
 identified  by  pid1  and  pid2 share a kernel resource such as virtual
 memory, file descriptors, and so on.

> 
> Cheers,
> Trevor
> 
> -- 
> This email may be signed or encrypted with GnuPG (http://www.gnupg.org).
> For more information, see http://en.wikipedia.org/wiki/Pretty_Good_Privacy