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From: Matthew Wilcox <willy@infradead.org>
To: Jann Horn <jannh@google.com>
Cc: Kees Cook <keescook@chromium.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Christoph Hellwig <hch@infradead.org>,
	Christopher Lameter <cl@linux.com>, Jiri Slaby <jslaby@suse.cz>,
	Julian Wiedmann <jwi@linux.ibm.com>,
	Ursula Braun <ubraun@linux.ibm.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	kernel list <linux-kernel@vger.kernel.org>,
	David Windsor <dave@nullcore.net>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux-MM <linux-mm@kvack.org>,
	linux-xfs@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Laura Abbott <labbott@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Dave Kleikamp <dave.kleikamp@oracle.com>, Jan Kara <jack@suse.cz>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Matthew Garrett <mjg59@google.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Michal Kubecek <mkubecek@suse.cz>
Subject: Re: [kernel-hardening] [PATCH 09/38] usercopy: Mark kmalloc caches as usercopy caches
Date: Sun, 2 Feb 2020 23:46:44 -0800	[thread overview]
Message-ID: <20200203074644.GD8731@bombadil.infradead.org> (raw)
In-Reply-To: <CAG48ez2ms+TDEXQdDONuQ1GG0K20E69nV1r_yjKxxYjYKv1VCg@mail.gmail.com>

On Sat, Feb 01, 2020 at 08:27:49PM +0100, Jann Horn wrote:
> FWIW, as far as I understand, usercopy doesn't actually have any
> effect on drivers that use the modern, proper APIs, since those don't
> use the slab allocator at all - as I pointed out in my last mail, the
> dma-kmalloc* slabs are used very rarely. (Which is good, because
> putting objects from less-than-page-size slabs into iommu entries is a
> terrible idea from a security and reliability perspective because it
> gives the hardware access to completely unrelated memory.) Instead,
> they get pages from the page allocator, and these pages may e.g. be
> allocated from the DMA, DMA32 or NORMAL zones depending on the
> restrictions imposed by hardware. So I think the usercopy restriction
> only affects a few oddball drivers (like this s390 stuff), which is
> why you're not seeing more bug reports caused by this.

Getting pages from the page allocator is true for dma_alloc_coherent()
and friends.  But it's not true for streaming DMA mappings (dma_map_*)
for which the memory usually comes from kmalloc().  If this is something
we want to fix (and I have an awful feeling we're going to regret it
if we say "no, we trust the hardware"), we're going to have to come up
with a new memory allocation API for these cases.  Or bounce bugger the
memory for devices we don't trust.

The problem with the dma_map_* API is that memory might end up being
allocated once and then used multiple times by different drivers.  eg if
I allocate an NFS packet, it might get sent first to eth0, then (when the
route fails) sent to eth1.  Similarly in storage, a RAID-5 driver might
map the same memory several times to send to different disk controllers.

  reply	other threads:[~2020-02-03  7:47 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-11  2:02 [kernel-hardening] [PATCH v5 00/38] Hardened usercopy whitelisting Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 01/38] usercopy: Remove pointer from overflow report Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 02/38] usercopy: Enhance and rename report_usercopy() Kees Cook
2018-01-11 17:06   ` [kernel-hardening] " Christopher Lameter
2018-01-14 20:57     ` Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 03/38] usercopy: Include offset in hardened usercopy report Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 04/38] lkdtm/usercopy: Adjust test to include an offset to check reporting Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 05/38] stddef.h: Introduce sizeof_field() Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 06/38] usercopy: Prepare for usercopy whitelisting Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 07/38] usercopy: WARN() on slab cache usercopy region violations Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 08/38] usercopy: Allow strict enforcement of whitelists Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 09/38] usercopy: Mark kmalloc caches as usercopy caches Kees Cook
2019-11-12  7:17   ` Jiri Slaby
2019-11-12 21:21     ` Kees Cook
2019-11-14 21:27       ` Kees Cook
2020-01-23  8:14         ` Jiri Slaby
2020-01-27 23:19           ` Kees Cook
2020-01-28  7:58             ` Christian Borntraeger
2020-01-28 23:01               ` Kees Cook
2020-01-29  9:26                 ` Ursula Braun
2020-01-29 16:43                 ` Christopher Lameter
2020-01-29 17:07                   ` Christian Borntraeger
2020-01-29 17:09                     ` Christoph Hellwig
2020-01-29 17:19                       ` Christian Borntraeger
2020-01-30 19:23                         ` Kees Cook
2020-01-31 12:03                           ` Jann Horn
2020-02-01 17:56                             ` Kees Cook
2020-02-01 19:27                               ` Jann Horn
2020-02-03  7:46                                 ` Matthew Wilcox [this message]
2020-02-03 17:41                                   ` Christoph Hellwig
2020-02-03 17:20                               ` Christopher Lameter
2020-04-07  8:00                             ` Vlastimil Babka
2020-04-07 11:05                               ` Christian Borntraeger
2020-04-20  7:53                               ` Jiri Slaby
2020-04-20 17:43                                 ` Kees Cook
2020-02-03 17:38                           ` Christoph Hellwig
2020-02-03 17:36                         ` Christoph Hellwig
2018-01-11  2:02 ` [kernel-hardening] [PATCH 10/38] dcache: Define usercopy region in dentry_cache slab cache Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 11/38] vfs: Define usercopy region in names_cache slab caches Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 12/38] vfs: Copy struct mount.mnt_id to userspace using put_user() Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 13/38] ext4: Define usercopy region in ext4_inode_cache slab cache Kees Cook
2018-01-11 17:01   ` [kernel-hardening] " Theodore Ts'o
2018-01-11 23:05     ` Kees Cook
2018-01-14 22:34       ` Matthew Wilcox
2018-01-11  2:02 ` [kernel-hardening] [PATCH 14/38] ext2: Define usercopy region in ext2_inode_cache " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 15/38] jfs: Define usercopy region in jfs_ip " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 16/38] befs: Define usercopy region in befs_inode_cache " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 17/38] exofs: Define usercopy region in exofs_inode_cache " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 18/38] orangefs: Define usercopy region in orangefs_inode_cache " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 19/38] ufs: Define usercopy region in ufs_inode_cache " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 20/38] vxfs: Define usercopy region in vxfs_inode " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 21/38] cifs: Define usercopy region in cifs_request " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 22/38] scsi: Define usercopy region in scsi_sense_cache " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 23/38] net: Define usercopy region in struct proto " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 24/38] ip: Define usercopy region in IP " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 25/38] caif: Define usercopy region in caif " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 26/38] sctp: Define usercopy region in SCTP " Kees Cook
2018-01-11  2:02 ` [kernel-hardening] [PATCH 27/38] sctp: Copy struct sctp_sock.autoclose to userspace using put_user() Kees Cook
2018-01-18 21:31   ` [kernel-hardening] " Laura Abbott
2018-01-18 21:36     ` Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 28/38] net: Restrict unwhitelisted proto caches to size 0 Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 29/38] fork: Define usercopy region in mm_struct slab caches Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 30/38] fork: Define usercopy region in thread_stack " Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 31/38] fork: Provide usercopy whitelisting for task_struct Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 32/38] x86: Implement thread_struct whitelist for hardened usercopy Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 33/38] arm64: " Kees Cook
2018-01-15 12:24   ` [kernel-hardening] " Dave P Martin
2018-01-15 20:06     ` Kees Cook
2018-01-16 12:33       ` Dave Martin
2018-03-26 16:22       ` Dave Martin
2018-03-26 17:41         ` Kees Cook
2018-03-27 12:32           ` Dave Martin
2018-01-11  2:03 ` [kernel-hardening] [PATCH 34/38] arm: " Kees Cook
2018-01-11 10:24   ` [kernel-hardening] " Russell King - ARM Linux
2018-01-11 23:21     ` Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 35/38] kvm: whitelist struct kvm_vcpu_arch Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 36/38] kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 37/38] usercopy: Restrict non-usercopy caches to size 0 Kees Cook
2018-01-11  2:03 ` [kernel-hardening] [PATCH 38/38] lkdtm: Update usercopy tests for whitelisting Kees Cook
2018-02-19 16:55 ` [PATCH] signals: Move put_compat_sigset to compat.h to silence hardened usercopy Matt Redfearn
2018-02-19 23:55   ` Kees Cook
2018-03-02 21:40     ` James Hogan

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