Re: [GIT PULL] kdbus for 4.1-rc1
From: Greg KH
Date: Thu Apr 23 2015 - 15:34:07 EST
On Thu, Apr 23, 2015 at 12:22:10PM -0700, Andy Lutomirski wrote:
> On Apr 23, 2015 11:56 AM, "Greg Kroah-Hartman"
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > On Thu, Apr 23, 2015 at 11:04:36AM -0700, Linus Torvalds wrote:
> > > On Thu, Apr 23, 2015 at 10:57 AM, Linus Torvalds
> > > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> > > >
> > > > If somebody is printing something, it shouldn't matter if it's "lpr"
> > > > or "firefox http://horses.and.trannyporn.my.little.pony.com/" that
> > > > does the printing.
> > >
> > > And btw, it's not just "this is information that shouldn't be logged".
> > >
> > > It's literally "information that should not *ever* be used". I can
> > > easily see some phone manufacturer deciding to do "value add" by
> > > adding a special case where a special vendor system manager program
> > > gets a back door to some service, because it needs to access the
> > > camera for user identification at login time, so there's some magic
> > >
> > > if (!strcmp(client->pid_comm, "vendor-login-pr"))
> > > return ACCESS_OK;
> > >
> > > because "it was the simplest way to do this", and the programmer knew
> > > it was a hack, but he needed to get it working because he had a
> > > deadline yesterday.
> > >
> > > And then somebody figures this out, and makes an app that takes
> > > pictures on your phone surreptitiously.
> > >
> > > No, we can't protect against vendors doing stupid things, but we very
> > > much also shouldn't make the kernel have interfaces that basically
> > > encourage people to do stupid things because they make irrelevant and
> > > wrongheaded data available.
> > Doing access control based on comm and cmdline is horrid, I totally
> > agree. But right now, any process in the system can read any other
> > process's comm and cmdline value out of /proc today. So removing it
> > from the metadata is fine for kdbus, I can live with that, but it really
> > isn't "preventing" anything that's not already visible to everyone, so
> > if someone wanting to be "bad" could always still log it or do anything
> > else they wanted with it.
> I feel like a broken record. This isn't true in general.
Works on my box :)
> Selinux can and, I believe, often does prevent this.
Ok, then the LSM patches for kdbus should be able to also mediate this
as well if needed. I haven't looked at the LSM kdbus patches in a long
time, so I don't remember exactly what they were looking at.
Again, I don't object to dropping this in kdbus, just confused as this
seemed to me to be something that is always available to all processes
anyway, we weren't adding something previously "hidden".
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