On Thu, Oct 06, 2016 at 01:47:47PM +0000, Roberts, William C wrote: > > -----Original Message----- > > From: Christoph Hellwig [mailto:h...@infradead.org] > > Sent: Thursday, October 6, 2016 9:32 AM > > To: Roberts, William C <william.c.robe...@intel.com> > > Cc: kernel-harden...@lists.openwall.com; cor...@lwn.net; linux- > > d...@vger.kernel.org; linux-ker...@vger.kernel.org > > Subject: Re: [PATCH] printk: introduce kptr_restrict level 3 > > > > On Wed, Oct 05, 2016 at 02:04:46PM -0400, william.c.robe...@intel.com wrote: > > > From: William Roberts <william.c.robe...@intel.com> > > > > > > Some out-of-tree modules do not use %pK and just use %p, as it's the > > > common C paradigm for printing pointers. Because of this, > > > kptr_restrict has no affect on the output and thus, no way to contain > > > the kernel address leak. > > > > So what? We a) don't care about out of tree modules and b) you could just > > triviall > > fix them up if you care. > > Out of tree modules still affect core kernel security. I would also bet > money, that somewhere > In-tree someone has put a %p when they wanted a %pK. So this method is just > quite error > prone. We currently have a blacklist approach versus whitelist.
grep says you have a point:
$ grep -IR 'seq_printf.*%p[^FfSsBRrhbMmIiEUVKNadCDgG].*&'
drivers/dma/qcom/hidma_dbg.c: seq_printf(s, "dev_trca=%p\n",
&dmadev->dev_trca);
drivers/dma/qcom/hidma_dbg.c: seq_printf(s, "dev_evca=%p\n",
&dmadev->dev_evca);
$ grep -IR 'pr_info.*%p[^FfSsBRrhbMmIiEUVKNadCDgG].*&'
drivers/misc/lkdtm_heap.c: pr_info("Allocated memory %p-%p\n", base,
&base[offset * 2]);
$ grep -IR 'pr_err.*%p[^FfSsBRrhbMmIiEUVKNadCDgG].*&'
drivers/net/ethernet/qlogic/qlge/qlge_dbg.c: pr_err("rx_ring->cqicb = %p\n",
&rx_ring->cqicb);
And these are just trivially greppable, low-hanging-fruit ones.
With somewhat broader greps, there seem to be lots more, but they'd
require manual review.
And in total, there are 13578 matches for %p[^FfSsBRrhbMmIiEUVKNadCDgG]
throughout the kernel. Reviewing all of those manually would suck.
signature.asc
Description: Digital signature
