* linux-next: manual merge of the selinux tree
@ 2008-07-07 12:51 Stephen Rothwell
2008-07-07 14:43 ` James Morris
0 siblings, 1 reply; 5+ messages in thread
From: Stephen Rothwell @ 2008-07-07 12:51 UTC (permalink / raw)
To: James Morris, Eric Paris, Stephen Smalley, Paul Moore
Cc: linux-next, Andrew Morton
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Hi all,
Today's linux-next merge of the selinux tree got a conflict in
fs/proc/task_mmu.c between commit
5d7e0d2bd98ef4f5a16ac9da1987ae655368dd6a ("Fix pagemap_read() use of
struct mm_walk") from Linus' tree and commit
ca9b1a1413bac6ea5e5c8cb81044a39bdb3b4bc8 ("Security: split proc ptrace
checking into read vs. attach") from the selinux tree.
The former removed some of the code that the latter changed. It is
probably worth a check on the code in pagemap_read to make sure I got it
right.
--
Cheers,
Stephen Rothwell sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: linux-next: manual merge of the selinux tree
2008-07-07 12:51 linux-next: manual merge of the selinux tree Stephen Rothwell
@ 2008-07-07 14:43 ` James Morris
2008-07-07 14:47 ` Stephen Smalley
0 siblings, 1 reply; 5+ messages in thread
From: James Morris @ 2008-07-07 14:43 UTC (permalink / raw)
To: Stephen Rothwell
Cc: Eric Paris, Stephen Smalley, Paul Moore, linux-next, Andrew Morton
On Mon, 7 Jul 2008, Stephen Rothwell wrote:
> Hi all,
>
> Today's linux-next merge of the selinux tree got a conflict in
> fs/proc/task_mmu.c between commit
> 5d7e0d2bd98ef4f5a16ac9da1987ae655368dd6a ("Fix pagemap_read() use of
> struct mm_walk") from Linus' tree and commit
> ca9b1a1413bac6ea5e5c8cb81044a39bdb3b4bc8 ("Security: split proc ptrace
> checking into read vs. attach") from the selinux tree.
>
> The former removed some of the code that the latter changed. It is
> probably worth a check on the code in pagemap_read to make sure I got it
> right.
I couldn't locate your updated version, but have resolved it in my own
tree (which is being rebased).
One thing we need to understand is why there were two separate
ptrace_may_attach() calls in the earlier version of pagemap_read().
- James
--
James Morris
<jmorris@namei.org>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: linux-next: manual merge of the selinux tree
2008-07-07 14:43 ` James Morris
@ 2008-07-07 14:47 ` Stephen Smalley
2008-07-08 8:49 ` Andrew Morton
0 siblings, 1 reply; 5+ messages in thread
From: Stephen Smalley @ 2008-07-07 14:47 UTC (permalink / raw)
To: James Morris
Cc: Stephen Rothwell, Eric Paris, Paul Moore, linux-next, Andrew Morton
On Tue, 2008-07-08 at 00:43 +1000, James Morris wrote:
> On Mon, 7 Jul 2008, Stephen Rothwell wrote:
>
> > Hi all,
> >
> > Today's linux-next merge of the selinux tree got a conflict in
> > fs/proc/task_mmu.c between commit
> > 5d7e0d2bd98ef4f5a16ac9da1987ae655368dd6a ("Fix pagemap_read() use of
> > struct mm_walk") from Linus' tree and commit
> > ca9b1a1413bac6ea5e5c8cb81044a39bdb3b4bc8 ("Security: split proc ptrace
> > checking into read vs. attach") from the selinux tree.
> >
> > The former removed some of the code that the latter changed. It is
> > probably worth a check on the code in pagemap_read to make sure I got it
> > right.
>
> I couldn't locate your updated version, but have resolved it in my own
> tree (which is being rebased).
>
> One thing we need to understand is why there were two separate
> ptrace_may_attach() calls in the earlier version of pagemap_read().
It could sleep in between the two calls.
--
Stephen Smalley
National Security Agency
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: linux-next: manual merge of the selinux tree
2008-07-07 14:47 ` Stephen Smalley
@ 2008-07-08 8:49 ` Andrew Morton
2008-07-08 12:19 ` Stephen Smalley
0 siblings, 1 reply; 5+ messages in thread
From: Andrew Morton @ 2008-07-08 8:49 UTC (permalink / raw)
To: Stephen Smalley
Cc: James Morris, Stephen Rothwell, Eric Paris, Paul Moore, linux-next
On Mon, 07 Jul 2008 10:47:34 -0400 Stephen Smalley <sds@tycho.nsa.gov> wrote:
>
> On Tue, 2008-07-08 at 00:43 +1000, James Morris wrote:
> > On Mon, 7 Jul 2008, Stephen Rothwell wrote:
> >
> > > Hi all,
> > >
> > > Today's linux-next merge of the selinux tree got a conflict in
> > > fs/proc/task_mmu.c between commit
> > > 5d7e0d2bd98ef4f5a16ac9da1987ae655368dd6a ("Fix pagemap_read() use of
> > > struct mm_walk") from Linus' tree and commit
> > > ca9b1a1413bac6ea5e5c8cb81044a39bdb3b4bc8 ("Security: split proc ptrace
> > > checking into read vs. attach") from the selinux tree.
> > >
> > > The former removed some of the code that the latter changed. It is
> > > probably worth a check on the code in pagemap_read to make sure I got it
> > > right.
> >
> > I couldn't locate your updated version, but have resolved it in my own
> > tree (which is being rebased).
> >
> > One thing we need to understand is why there were two separate
> > ptrace_may_attach() calls in the earlier version of pagemap_read().
>
> It could sleep in between the two calls.
>
This is basically meaningless? Other threads could be running, accessing
this mm_struct. Other processes can be doing stuff. Preemption can
happen.
Are we missing some locking here?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: linux-next: manual merge of the selinux tree
2008-07-08 8:49 ` Andrew Morton
@ 2008-07-08 12:19 ` Stephen Smalley
0 siblings, 0 replies; 5+ messages in thread
From: Stephen Smalley @ 2008-07-08 12:19 UTC (permalink / raw)
To: Andrew Morton
Cc: James Morris, Stephen Rothwell, Eric Paris, Paul Moore, linux-next
On Tue, 2008-07-08 at 01:49 -0700, Andrew Morton wrote:
> On Mon, 07 Jul 2008 10:47:34 -0400 Stephen Smalley <sds@tycho.nsa.gov> wrote:
>
> >
> > On Tue, 2008-07-08 at 00:43 +1000, James Morris wrote:
> > > On Mon, 7 Jul 2008, Stephen Rothwell wrote:
> > >
> > > > Hi all,
> > > >
> > > > Today's linux-next merge of the selinux tree got a conflict in
> > > > fs/proc/task_mmu.c between commit
> > > > 5d7e0d2bd98ef4f5a16ac9da1987ae655368dd6a ("Fix pagemap_read() use of
> > > > struct mm_walk") from Linus' tree and commit
> > > > ca9b1a1413bac6ea5e5c8cb81044a39bdb3b4bc8 ("Security: split proc ptrace
> > > > checking into read vs. attach") from the selinux tree.
> > > >
> > > > The former removed some of the code that the latter changed. It is
> > > > probably worth a check on the code in pagemap_read to make sure I got it
> > > > right.
> > >
> > > I couldn't locate your updated version, but have resolved it in my own
> > > tree (which is being rebased).
> > >
> > > One thing we need to understand is why there were two separate
> > > ptrace_may_attach() calls in the earlier version of pagemap_read().
> >
> > It could sleep in between the two calls.
> >
>
> This is basically meaningless? Other threads could be running, accessing
> this mm_struct. Other processes can be doing stuff. Preemption can
> happen.
>
> Are we missing some locking here?
I think so. mm_for_maps() seems like the way to go - holds task lock
across both mm extraction/validation and __ptrace_may_attach check.
I'm guessing that the writer of pagemap_read took his cue from mem_read,
which likewise does two checks (via check_mem_permission), seemingly
with the same problem.
environ_read() only checks ptrace_may_attach on entry independent of mm
extraction. Seemingly unsafe unless I'm missing something.
--
Stephen Smalley
National Security Agency
^ permalink raw reply [flat|nested] 5+ messages in thread
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2008-07-07 12:51 linux-next: manual merge of the selinux tree Stephen Rothwell
2008-07-07 14:43 ` James Morris
2008-07-07 14:47 ` Stephen Smalley
2008-07-08 8:49 ` Andrew Morton
2008-07-08 12:19 ` Stephen Smalley
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