linux-kernel - Re: sysfs: tagged directories not merged completely yet

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]

Message-ID: <20081007225424.GA9430@us.ibm.com>
Date:	Tue, 7 Oct 2008 17:54:24 -0500
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	Greg KH <greg@...ah.com>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Al Viro <viro@...IV.linux.org.uk>,
	Benjamin Thery <benjamin.thery@...l.net>,
	linux-kernel@...r.kernel.org, Al Viro <viro@....linux.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>
Subject: Re: sysfs: tagged directories not merged completely yet

Quoting Greg KH (greg@...ah.com):
> On Tue, Oct 07, 2008 at 01:27:17AM -0700, Eric W. Biederman wrote:
> > Unless someone will give an example of how having multiple superblocks
> > sharing inodes is a problem in practice for sysfs and call it good
> > for 2.6.28.  Certainly it shouldn't be an issue if the network namespace
> > code is compiled out.  And it should greatly improve testing of the
> > network namespace to at least have access to sysfs.
> 
> But if the network namespace code is in?  THen we have problems, right?
> And that's the whole point here.
> 
> The fact that you are trying to limit userspace view of in-kernel data
> structures, based on that specific user, is, in my opinion, crazy.
> 
> Why not just keep all users from seeing sysfs, and then have a user
> daemon doing something on top of FUSE if you really want to see this
> kind of stuff.

Well the blocker is really that when you create a new network namespace,
it wants to create a new loopback interface, but
/sys/devices/virtual/net/lo already exists.  That's the same issue with
user namespace when the fair scheduler is enabled, which tries to
re-create /sys/kernel/uids/0.

Otherwise yeah at least for my own uses, containers wouldn't need to
look at /sys at all.

Heck you wouldn't even need FUSE, just mount -t tmpfs /sys/class/net
and manually link the right devices from /sys/devices/virtual/net.

-serge
--
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/