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 HAVE_ARCH_HARDENED_USERCOPY
+ bool
+ help
+ The architecture supports CONFIG_HARDENED_USERCOPY by
+ calling check_object_size() just before performing the
+ userspace copies in the low level implementation of
+ copy_to_user() and copy_from_user().
+
+config HARDENED_USERCOPY
+ bool "Harden memory copies between kernel and userspace"
+ depends on HAVE_ARCH_HARDENED_USERCOPY
+ depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
+ select BUG
+ help
+ This option checks for obviously wrong memory regions when
+ copying memory to/from the kernel (via copy_to_user() and
+ copy_from_user() functions) by rejecting memory ranges that
+ are larger than the specified heap object, span multiple
+ separately allocates pages, are not on the process stack,
+ or are part of the kernel text. This kills entire classes
+ of heap overflow exploits and similar kernel memory exposures.
+
+config HARDENED_USERCOPY_PAGESPAN
+ bool "Refuse to copy allocations that span multiple pages"
+ depends on HARDENED_USERCOPY
+ depends on EXPERT
+ help
+ When a multi-page allocation is done without __GFP_COMP,
+ hardened usercopy will reject attempts to copy it. There are,
+ however, several cases of this in the kernel that have not all
+ been removed. This config is intended to be used only while
+ trying to find such users.
+
source security/selinux/Kconfig
source security/smack/Kconfig
source security/tomoyo/Kconfig