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Groups > linux.kernel > #1722014

[PATCH v2 18/30] net: Define usercopy region in struct proto slab cache

From Kees Cook <keescook@chromium.org>
Newsgroups linux.kernel
Subject [PATCH v2 18/30] net: Define usercopy region in struct proto slab cache
Date 2017-08-29 00:00 +0200
Message-ID <ujAeB-2oT-9@gated-at.bofh.it> (permalink)
References <ujzVf-2ie-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: David Windsor <dave@nullcore.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@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: Kees Cook <keescook@chromium.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 7c0632c7e870..170d5b2dbcb6 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 ac2a404c73eb..02dab98ca3e3 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3109,8 +3109,12 @@ 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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[PATCH v2 00/30] Hardened usercopy whitelisting Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 07/30] ext4: Define usercopy region in ext4_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 09/30] jfs: Define usercopy region in jfs_ip slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 06/30] vfs: Copy struct mount.mnt_id to userspace using put_user() Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 05/30] vfs: Define usercopy region in names_cache slab caches Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 08/30] ext2: Define usercopy region in ext2_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
    Re: [PATCH v2 08/30] ext2: Define usercopy region in  ext2_inode_cache slab cache Jan Kara <jack@suse.cz> - 2017-08-30 13:30 +0200
  [PATCH v2 13/30] ufs: Define usercopy region in ufs_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 16/30] cifs: Define usercopy region in cifs_request slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 02/30] usercopy: Enforce slab cache usercopy region boundaries Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 20/30] caif: Define usercopy region in caif proto slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 01/30] usercopy: Prepare for usercopy whitelisting Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 11/30] exofs: Define usercopy region in exofs_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 04/30] dcache: Define usercopy region in dentry_cache slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
  [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
    Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab cache Kees Cook <keescook@chromium.org> - 2017-08-29 00:00 +0200
      Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-29 06:50 +0200
        Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab cache Kees Cook <keescook@chromium.org> - 2017-08-29 20:50 +0200
          Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-29 21:10 +0200
          Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache Dave Chinner <david@fromorbit.com> - 2017-08-30 00:20 +0200
            Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab cache Kees Cook <keescook@chromium.org> - 2017-08-30 00:30 +0200
    Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-29 00:00 +0200
    Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache Christoph Hellwig <hch@infradead.org> - 2017-08-29 10:20 +0200
      Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache Dave Chinner <david@fromorbit.com> - 2017-08-29 14:40 +0200
        Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache Christoph Hellwig <hch@infradead.org> - 2017-08-29 14:50 +0200
          Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache Dave Chinner <david@fromorbit.com> - 2017-08-30 00:00 +0200
            Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache Christoph Hellwig <hch@infradead.org> - 2017-08-30 09:20 +0200
              Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache Dave Chinner <david@fromorbit.com> - 2017-08-30 10:10 +0200
                Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab  cache Christoph Hellwig <hch@infradead.org> - 2017-08-30 10:40 +0200
      Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab cache Kees Cook <keescook@chromium.org> - 2017-08-29 21:00 +0200
  [PATCH v2 10/30] befs: Define usercopy region in befs_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:40 +0200
    Re: [PATCH v2 10/30] befs: Define usercopy region in befs_inode_cache  slab cache Luis de Bethencourt <luisbg@kernel.org> - 2017-08-29 12:20 +0200
      Re: [PATCH v2 10/30] befs: Define usercopy region in befs_inode_cache  slab cache Kees Cook <keescook@chromium.org> - 2017-08-29 17:40 +0200
        Re: [PATCH v2 10/30] befs: Define usercopy region in befs_inode_cache  slab cache Luis de Bethencourt <luisbg@kernel.org> - 2017-08-29 19:20 +0200
  [PATCH v2 25/30] fork: Define usercopy region in thread_stack slab caches Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
    Re: [kernel-hardening] [PATCH v2 25/30] fork: Define usercopy  region in thread_stack slab caches Rik van Riel <riel@redhat.com> - 2017-08-30 21:00 +0200
  [PATCH v2 21/30] sctp: Define usercopy region in SCTP proto slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
  [PATCH v2 19/30] ip: Define usercopy region in IP proto slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
  [PATCH v2 22/30] sctp: Copy struct sctp_sock.autoclose to userspace using put_user() Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
  [PATCH v2 29/30] arm: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
  [PATCH v2 30/30] usercopy: Restrict non-usercopy caches to size 0 Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
  [PATCH v2 14/30] vxfs: Define usercopy region in vxfs_inode slab cache Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
  [PATCH v2 24/30] fork: Define usercopy region in mm_struct slab caches Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
    Re: [kernel-hardening] [PATCH v2 24/30] fork: Define usercopy  region in mm_struct slab caches Rik van Riel <riel@redhat.com> - 2017-08-30 21:30 +0200
  [PATCH v2 23/30] net: Restrict unwhitelisted proto caches to size 0 Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
  [PATCH v2 26/30] fork: Provide usercopy whitelisting for task_struct Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
    Re: [kernel-hardening] [PATCH v2 26/30] fork: Provide usercopy  whitelisting for task_struct Rik van Riel <riel@redhat.com> - 2017-08-30 21:00 +0200
  [PATCH v2 28/30] arm64: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-08-28 23:50 +0200
  [PATCH v2 27/30] x86: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-08-29 00:00 +0200
    Re: [kernel-hardening] [PATCH v2 27/30] x86: Implement  thread_struct whitelist for hardened usercopy Rik van Riel <riel@redhat.com> - 2017-08-30 21:00 +0200
  [PATCH v2 18/30] net: Define usercopy region in struct proto slab cache Kees Cook <keescook@chromium.org> - 2017-08-29 00:00 +0200

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