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Commit 30c2c9f1 authored by David Windsor's avatar David Windsor Committed by Kees Cook
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net: Define usercopy region in struct proto slab cache 



In support of usercopy hardening, this patch defines a region in the
struct proto slab cache in which userspace copy operations are allowed.
Some protocols need to copy objects to/from userspace, and they can
declare the region via their proto structure with the new usersize and
useroffset fields. Initially, if no region is specified (usersize ==
0), the entire field is marked as whitelisted. This allows protocols
to be whitelisted in subsequent patches. Once all protocols have been
annotated, the full-whitelist default can be removed.

This region is known as the slab cache's usercopy region. Slab caches
can now check that each dynamically sized copy operation involving
cache-managed memory falls entirely within the slab's usercopy region.

This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code are
mine and don't reflect the original grsecurity/PaX code.

Signed-off-by: default avatarDavid Windsor <dave@nullcore.net>
[kees: adjust commit log, split off per-proto patches]
[kees: add logic for by-default full-whitelist]
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 0afe76e8

include/net/sock.h

+2 −0
Original line number Diff line number Diff line
@@ -1112,6 +1112,8 @@ struct proto { 
	struct kmem_cache	*slab;

	unsigned int		obj_size;

	slab_flags_t		slab_flags;

	size_t			useroffset;	/* Usercopy region offset */

	size_t			usersize;	/* Usercopy region size */



	struct percpu_counter	*orphan_count;

net/core/sock.c

+5 −1
Original line number Diff line number Diff line
@@ -3151,8 +3151,12 @@ static int req_prot_init(const struct proto *prot) 
int proto_register(struct proto *prot, int alloc_slab)

{

	if (alloc_slab) {

		prot->slab = kmem_cache_create(prot->name, prot->obj_size, 0,

		prot->slab = kmem_cache_create_usercopy(prot->name,

					prot->obj_size, 0,

					SLAB_HWCACHE_ALIGN | prot->slab_flags,

					prot->usersize ? prot->useroffset : 0,

					prot->usersize ? prot->usersize

						       : prot->obj_size,

					NULL);



		if (prot->slab == NULL) {