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Date: Wed, 20 Sep 2017 13:45:24 -0700
From: Kees Cook <keescook@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
David Windsor <dave@...lcore.net>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Paolo Abeni <pabeni@...hat.com>,
David Howells <dhowells@...hat.com>,
netdev@...r.kernel.org,
linux-fsdevel@...r.kernel.org,
linux-mm@...ck.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH v3 18/31] net: Define usercopy region in struct proto slab cache
From: David Windsor <dave@...lcore.net>
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 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: David Windsor <dave@...lcore.net>
[kees: adjust commit log, split off per-proto patches]
[kees: add logic for by-default full-whitelist]
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Paolo Abeni <pabeni@...hat.com>
Cc: David Howells <dhowells@...hat.com>
Cc: netdev@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
include/net/sock.h | 2 ++
net/core/sock.c | 6 +++++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index 03a362568357..13c2d1b48c86 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1106,6 +1106,8 @@ struct proto {
struct kmem_cache *slab;
unsigned int obj_size;
int slab_flags;
+ size_t useroffset; /* Usercopy region offset */
+ size_t usersize; /* Usercopy region size */
struct percpu_counter *orphan_count;
diff --git a/net/core/sock.c b/net/core/sock.c
index 9b7b6bbb2a23..832dfb03102e 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3165,8 +3165,12 @@ 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) {
--
2.7.4
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