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Tue, 23 May 2023 23:15:13 -0700 (PDT) Date: Wed, 24 May 2023 15:15:26 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: David Rientjes Cc: Kees Cook , David Hildenbrand , Lorenzo Stoakes , Vlastimil Babka , Christoph Lameter , Pekka Enberg , Joonsoo Kim , Roman Gushchin , linux-mm@kvack.org, linux-hardening@vger.kernel.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/slab: remove HAVE_HARDENED_USERCOPY_ALLOCATOR Message-ID: References: <20230523073136.4900-1-vbabka@suse.cz> <310077ed-6f3f-41fe-afcf-36500a9408ec@lucifer.local> <623a87c6-c0d2-799a-c39e-0d14dcdfa6df@suse.cz> <202305231001.08BC6058@keescook> <7a16b351-c7f6-b6a3-869b-5163c0d0793f@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7a16b351-c7f6-b6a3-869b-5163c0d0793f@google.com> X-Rspamd-Queue-Id: 9E40018000D X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: gzo37t13qd9pg7k7bo4qq3wtzp3psitc X-HE-Tag: 1684908915-793328 X-HE-Meta: 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 YXhpatBx 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, May 23, 2023 at 05:31:47PM -0700, David Rientjes wrote: > On Tue, 23 May 2023, Kees Cook wrote: > > > On Tue, May 23, 2023 at 10:14:24AM +0200, David Hildenbrand wrote: > > > On 23.05.23 09:56, Lorenzo Stoakes wrote: > > > > On Tue, May 23, 2023 at 09:46:46AM +0200, Vlastimil Babka wrote: > > > > > On 5/23/23 09:42, Lorenzo Stoakes wrote: > > > > > > On Tue, May 23, 2023 at 09:31:36AM +0200, Vlastimil Babka wrote: > > > > > > > With SLOB removed, both remaining allocators support hardened usercopy, > > > > > > > so remove the config and associated #ifdef. > > > > > > > > > > > > > > Signed-off-by: Vlastimil Babka > > > > > > > --- > > > > > > > mm/Kconfig | 2 -- > > > > > > > mm/slab.h | 9 --------- > > > > > > > security/Kconfig | 8 -------- > > > > > > > 3 files changed, 19 deletions(-) > > > > > > > > > > > > > > diff --git a/mm/Kconfig b/mm/Kconfig > > > > > > > index 7672a22647b4..041f0da42f2b 100644 > > > > > > > --- a/mm/Kconfig > > > > > > > +++ b/mm/Kconfig > > > > > > > @@ -221,7 +221,6 @@ choice > > > > > > > config SLAB > > > > > > > bool "SLAB" > > > > > > > depends on !PREEMPT_RT > > > > > > > - select HAVE_HARDENED_USERCOPY_ALLOCATOR > > > > > > > help > > > > > > > The regular slab allocator that is established and known to work > > > > > > > well in all environments. It organizes cache hot objects in > > > > > > > @@ -229,7 +228,6 @@ config SLAB > > > > > > > > > > > > > > config SLUB > > > > > > > bool "SLUB (Unqueued Allocator)" > > > > > > > - select HAVE_HARDENED_USERCOPY_ALLOCATOR > > > > > > > help > > > > > > > SLUB is a slab allocator that minimizes cache line usage > > > > > > > instead of managing queues of cached objects (SLAB approach). > > > > > > > diff --git a/mm/slab.h b/mm/slab.h > > > > > > > index f01ac256a8f5..695ef96b4b5b 100644 > > > > > > > --- a/mm/slab.h > > > > > > > +++ b/mm/slab.h > > > > > > > @@ -832,17 +832,8 @@ struct kmem_obj_info { > > > > > > > void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab); > > > > > > > #endif > > > > > > > > > > > > > > -#ifdef CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR > > > > > > > void __check_heap_object(const void *ptr, unsigned long n, > > > > > > > const struct slab *slab, bool to_user); > > > > > > > -#else > > > > > > > -static inline > > > > > > > -void __check_heap_object(const void *ptr, unsigned long n, > > > > > > > - const struct slab *slab, bool to_user) > > > > > > > -{ > > > > > > > -} > > > > > > > -#endif > > > > > > > > > > > > Hm, this is still defined in slab.c/slub.c and invoked in usercopy.c, do we > > > > > > not want the prototype? > > > > > > > > > > Well I didn't delete the prototype, just the ifdef/else around, so now it's > > > > > there unconditionally. > > > > > > > > > > > Perhaps replacing with #ifdef > > > > > > CONFIG_HARDENED_USERCOPY instead? I may be missing something here :) > > > > > > > > > > Putting it under that #ifdef would work and match that the implementations > > > > > of that function are under that same ifdef, but maybe it's unnecessary noise > > > > > in the header? > > > > > > > > > > > > > Yeah my brain inserted extra '-'s there, sorry! > > > > > > > > Given we only define __check_heap_object() in sl[au]b.c if > > > > CONFIG_HARDENED_USERCOPY wouldn't we need to keep the empty version around > > > > if !CONFIG_HARDENED_USERCOPY since check_heap_object() appears to be called > > > > unconditionally? > > > > > > > > > > The file is only compiled with CONFIG_HARDENED_USERCOPY: > > > > > > mm/Makefile:obj-$(CONFIG_HARDENED_USERCOPY) += usercopy.o > > > > Right. > > > > > Reviewed-by: David Hildenbrand > > > > Thanks! > > > > Reviewed-by: Kees Cook > > > > Acked-by: David Rientjes looks fine to me, Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> -- Hyeonggon Yoo Doing kernel stuff as a hobby Undergraduate | Chungnam National University Dept. Computer Science & Engineering