From: Joe Perches <joe@perches.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
"Tobin C. Harding" <me@tobin.cc>,
Kees Cook <keescook@chromium.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: [GIT PULL] hash addresses printed with %p
Date: Wed, 29 Nov 2017 12:54:00 -0800 [thread overview]
Message-ID: <1511988840.19952.76.camel@perches.com> (raw)
In-Reply-To: <CA+55aFzzo=+qnHg174s_qmaGQ6uHWmGwQb2oO77RX3BcjDfwEw@mail.gmail.com>
On Wed, 2017-11-29 at 11:39 -0800, Linus Torvalds wrote:
> On Wed, Nov 29, 2017 at 11:22 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > What I didn't realize until after pulling this and testing, is that it
> > completely breaks '%pK'.
> >
> > We've marked various sensitive pointers with %pK, but that is now
> > _less_ secure than %p is, since it doesn't do the hashing because of
> > how you refactored the %pK code out of 'pointer()' into its own
> > function.
> >
> > So now %pK ends up using the plain "number()" function. Reading
> > through the series I hadn't noticed that the refactoring ended up
> > messing with that.
> >
> > I'll fix it up somehow.
>
> I ended up just doing this:
>
> case 'K':
> + if (!kptr_restrict)
> + break;
> return restricted_pointer(buf, end, ptr, spec);
>
> which basically says that "if kptr_restrict isn't set, %pK is the same as %p".
>
> Now, I feel that we should probably get rid of 'restricted_pointer()'
> entirely, since now the regular '%p' is arguably safer than '%pK' is,
> but I also didn't want to mess with the case that I have never used
> and that most distros don't seem to set.
>
> Alternatively, we might make the 'K' behavior of clearing the pointer
> be in addition to the other flags, so that you could do '%pxK' and get
> the old %pK behavior. But since I am not a huge fan of %pK to begin
> with, I can't find it in myself to care too much.
>
> So I'll leave that for Kees & co to decide on. Comments?
I'd prefer a global sed of '%pK' to '%pxK' and remove '%pK' altogether
next prev parent reply other threads:[~2017-11-29 20:54 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-29 4:59 [GIT PULL] hash addresses printed with %p Tobin C. Harding
2017-11-29 19:22 ` Linus Torvalds
2017-11-29 19:39 ` Linus Torvalds
2017-11-29 20:54 ` Joe Perches [this message]
2017-11-29 21:05 ` Linus Torvalds
2017-11-29 21:31 ` Kees Cook
2017-11-29 21:08 ` Tobin C. Harding
2017-11-29 21:14 ` Linus Torvalds
2017-11-29 21:28 ` Tobin C. Harding
2017-11-29 21:36 ` Linus Torvalds
2017-11-30 16:32 ` Greg Kroah-Hartman
2017-11-30 17:10 ` Greg Kroah-Hartman
2017-11-30 17:18 ` Ard Biesheuvel
2017-12-01 9:48 ` Greg Kroah-Hartman
2017-12-01 9:54 ` Ard Biesheuvel
2017-12-01 15:34 ` Greg Kroah-Hartman
2017-12-01 16:33 ` Kees Cook
2017-12-02 8:51 ` Ard Biesheuvel
2017-12-02 22:22 ` Matt Fleming
2017-12-03 1:15 ` Dave Young
2017-12-04 2:02 ` Dave Young
2017-12-04 2:33 ` Joe Perches
2017-12-04 2:39 ` Dave Young
2017-12-04 7:36 ` Greg Kroah-Hartman
2017-12-04 9:29 ` Dave Young
2017-12-04 9:34 ` Greg Kroah-Hartman
2017-12-04 9:48 ` Ard Biesheuvel
2017-12-04 9:59 ` Greg Kroah-Hartman
2017-12-04 10:03 ` Ard Biesheuvel
2017-12-04 10:11 ` Greg Kroah-Hartman
2017-12-04 12:51 ` David Laight
2017-12-04 14:00 ` Greg Kroah-Hartman
2017-12-05 5:14 ` Dave Young
2017-12-05 8:09 ` Greg Kroah-Hartman
2017-12-05 8:45 ` Dave Young
2017-12-05 8:52 ` Greg Kroah-Hartman
2017-12-05 9:25 ` Ard Biesheuvel
2017-12-05 10:15 ` Greg Kroah-Hartman
2017-12-05 9:32 ` Dave Young
2017-12-05 9:24 ` Dave Young
2017-12-05 10:14 ` Greg Kroah-Hartman
2017-11-30 23:17 ` Linus Torvalds
2017-12-01 9:47 ` Greg Kroah-Hartman
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