linux-kernel - [patch] Staging: tidspbridge: make mmap root-only so it is not a security problem

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Message-ID: <20131130204237.GA17912@amd.pavel.ucw.cz>
Date:	Sat, 30 Nov 2013 21:42:37 +0100
From:	Pavel Machek <pavel@....cz>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	Ivajlo Dimitrov <ivo.g.dimitrov.75@...il.com>,
	gregkh@...uxfoundation.org,
	Ивайло Димитров 
	<freemangordon@....bg>, pali.rohar@...il.com, sre@...g0.de,
	omar.ramirez@...itl.com, tony@...mide.com,
	felipe.contreras@...il.com, s-anna@...com, nm@...com,
	ohad@...ery.com, stable@...r.kernel.org,
	linux-kernel@...r.kernel.org, nico@...lde.de
Subject: [patch] Staging: tidspbridge: make mmap root-only so it is not a
 security problem


mmap in tidspbridge is missing range-checks. For now, make this
interface root-only, so that it does not cause security problems.

Signed-off-by: Pavel Machek <pavel@....cz>
Reported-by: Nico Golde <nico@...lde.de>
Reported-by: Fabian Yamaguchi <fabs@...sec.de>

---

On Sat 2013-11-30 22:49:35, Dan Carpenter wrote:
> On Sat, Nov 30, 2013 at 08:19:32PM +0100, Pavel Machek wrote:
> > so perhaps Nico Golde or Dan Carpenter can elaborate? I Cc-ed them
> > now.
> > 
> > Or is it some kind of super-secret issue and still under embargo for
> > 10 days?
> 
> Nope,  it's not secret.  Here is the original report from Nico and
> Fabian.  Please give them credit when you fix the bug.

Thanks!

> Felipe Contreras says we could just remove mmap() support and the driver
> would still work, but no one has submitted a patch to do that.  Really
> this driver needs an actual maintainer who will respond to security bugs
> and also start to move the driver out of staging.

There starts to be real traction around Nokia N900, so I believe it is
going to be fixed. (And with Nemo/Mer getting popularity due to Jolla,
it should get even better).

But no, I did not figure out how to run Nemo in qemu, yet...
									Pavel 

diff --git a/drivers/staging/tidspbridge/rmgr/drv_interface.c b/drivers/staging/tidspbridge/rmgr/drv_interface.c
index 1aa4a3f..8533e67 100644
--- a/drivers/staging/tidspbridge/rmgr/drv_interface.c
+++ b/drivers/staging/tidspbridge/rmgr/drv_interface.c
@@ -258,7 +258,10 @@ err:
 /* This function maps kernel space memory to user space memory. */
 static int bridge_mmap(struct file *filp, struct vm_area_struct *vma)
 {
-	u32 status;
+	int status;
+
+	if (!capable(CAP_SYS_RAWIO))
+		return -EPERM;
 
 	/* VM_IO | VM_DONTEXPAND | VM_DONTDUMP are set by remap_pfn_range() */
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
@@ -271,10 +274,10 @@ static int bridge_mmap(struct file *filp, struct vm_area_struct *vma)
 	status = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
 				 vma->vm_end - vma->vm_start,
 				 vma->vm_page_prot);
-	if (status != 0)
-		status = -EAGAIN;
+	if (status)
+		return -EAGAIN;
 
-	return status;
+	return 0;
 }
 
 static const struct file_operations bridge_fops = {

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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