linux-kernel - [PATCH] mm/slab: remove HAVE_HARDENED_USERCOPY

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Message-Id: <20230523073136.4900-1-vbabka@suse.cz>
Date:   Tue, 23 May 2023 09:31:36 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:     Roman Gushchin <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>,
        Kees Cook <keescook@...omium.org>, linux-mm@...ck.org,
        linux-hardening@...r.kernel.org, patches@...ts.linux.dev,
        linux-kernel@...r.kernel.org, Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH] mm/slab: remove HAVE_HARDENED_USERCOPY_ALLOCATOR

With SLOB removed, both remaining allocators support hardened usercopy,
so remove the config and associated #ifdef.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 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
-
 #ifdef CONFIG_SLUB_DEBUG
 void skip_orig_size_check(struct kmem_cache *s, const void *object);
 #endif
diff --git a/security/Kconfig b/security/Kconfig
index 97abeb9b9a19..52c9af08ad35 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -127,16 +127,8 @@ config LSM_MMAP_MIN_ADDR
 	  this low address space will need the permission specific to the
 	  systems running LSM.
 
-config HAVE_HARDENED_USERCOPY_ALLOCATOR
-	bool
-	help
-	  The heap allocator implements __check_heap_object() for
-	  validating memory ranges against heap object sizes in
-	  support of CONFIG_HARDENED_USERCOPY.
-
 config HARDENED_USERCOPY
 	bool "Harden memory copies between kernel and userspace"
-	depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
 	imply STRICT_DEVMEM
 	help
 	  This option checks for obviously wrong memory regions when
-- 
2.40.1