Linux-Bluetooth Archive on lore.kernel.org
 help / color / Atom feed
From: David Laight <David.Laight@ACULAB.COM>
To: 'David Miller' <davem@davemloft.net>, "hch@lst.de" <hch@lst.de>
Cc: "kuba@kernel.org" <kuba@kernel.org>,
	"ast@kernel.org" <ast@kernel.org>,
	"daniel@iogearbox.net" <daniel@iogearbox.net>,
	"kuznet@ms2.inr.ac.ru" <kuznet@ms2.inr.ac.ru>,
	"yoshfuji@linux-ipv6.org" <yoshfuji@linux-ipv6.org>,
	"edumazet@google.com" <edumazet@google.com>,
	"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"netfilter-devel@vger.kernel.org"
	<netfilter-devel@vger.kernel.org>,
	"coreteam@netfilter.org" <coreteam@netfilter.org>,
	"linux-sctp@vger.kernel.org" <linux-sctp@vger.kernel.org>,
	"linux-hams@vger.kernel.org" <linux-hams@vger.kernel.org>,
	"linux-bluetooth@vger.kernel.org"
	<linux-bluetooth@vger.kernel.org>,
	"bridge@lists.linux-foundation.org" 
	<bridge@lists.linux-foundation.org>,
	"linux-can@vger.kernel.org" <linux-can@vger.kernel.org>,
	"dccp@vger.kernel.org" <dccp@vger.kernel.org>,
	"linux-decnet-user@lists.sourceforge.net" 
	<linux-decnet-user@lists.sourceforge.net>,
	"linux-wpan@vger.kernel.org" <linux-wpan@vger.kernel.org>,
	"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
	"mptcp@lists.01.org" <mptcp@lists.01.org>,
	"lvs-devel@vger.kernel.org" <lvs-devel@vger.kernel.org>,
	"rds-devel@oss.oracle.com" <rds-devel@oss.oracle.com>,
	"linux-afs@lists.infradead.org" <linux-afs@lists.infradead.org>,
	"tipc-discussion@lists.sourceforge.net" 
	<tipc-discussion@lists.sourceforge.net>,
	"linux-x25@vger.kernel.org" <linux-x25@vger.kernel.org>
Subject: RE: get rid of the address_space override in setsockopt v2
Date: Mon, 27 Jul 2020 09:51:45 +0000
Message-ID: <8ae792c27f144d4bb5cbea0c1cce4eed@AcuMS.aculab.com> (raw)
In-Reply-To: <20200724.154342.1433271593505001306.davem@davemloft.net>

From: David Miller
> Sent: 24 July 2020 23:44
> 
> From: Christoph Hellwig <hch@lst.de>
> Date: Thu, 23 Jul 2020 08:08:42 +0200
> 
> > setsockopt is the last place in architecture-independ code that still
> > uses set_fs to force the uaccess routines to operate on kernel pointers.
> >
> > This series adds a new sockptr_t type that can contained either a kernel
> > or user pointer, and which has accessors that do the right thing, and
> > then uses it for setsockopt, starting by refactoring some low-level
> > helpers and moving them over to it before finally doing the main
> > setsockopt method.
> >
> > Note that apparently the eBPF selftests do not even cover this path, so
> > the series has been tested with a testing patch that always copies the
> > data first and passes a kernel pointer.  This is something that works for
> > most common sockopts (and is something that the ePBF support relies on),
> > but unfortunately in various corner cases we either don't use the passed
> > in length, or in one case actually copy data back from setsockopt, or in
> > case of bpfilter straight out do not work with kernel pointers at all.
> >
> > Against net-next/master.
> >
> > Changes since v1:
> >  - check that users don't pass in kernel addresses
> >  - more bpfilter cleanups
> >  - cosmetic mptcp tweak
> 
> Series applied to net-next, I'm build testing and will push this out when
> that is done.

Hmmm... this code does:

int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
		int optlen)
{
	sockptr_t optval;
	char *kernel_optval = NULL;
	int err, fput_needed;
	struct socket *sock;

	if (optlen < 0)
		return -EINVAL;

	err = init_user_sockptr(&optval, user_optval);
	if (err)
		return err;

And the called code does:
	if (copy_from_sockptr(&opt, optbuf, sizeof(opt)))
		return -EFAULT;


Which means that only the base of the user's buffer is checked
for being in userspace.

I'm sure there is code that processes options in chunks.
This probably means it is possible to put a chunk boundary
at the end of userspace and continue processing the very start
of kernel memory.

At best this faults on the kernel copy code and crashes the system.

Maybe there wasn't any code that actually incremented the user address.
But it is hardly robust.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  parent reply index

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-23  6:08 Christoph Hellwig
2020-07-23  6:08 ` [PATCH 01/26] bpfilter: fix up a sparse annotation Christoph Hellwig
2020-07-23 11:14   ` Luc Van Oostenryck
2020-07-23  6:08 ` [PATCH 02/26] net/bpfilter: split __bpfilter_process_sockopt Christoph Hellwig
2020-07-23  6:08 ` [PATCH 03/26] bpfilter: reject kernel addresses Christoph Hellwig
2020-07-23 14:42   ` David Laight
2020-07-23 14:44     ` 'Christoph Hellwig'
2020-07-23 14:56       ` David Laight
2020-07-23  6:08 ` [PATCH 04/26] net: add a new sockptr_t type Christoph Hellwig
2020-07-23 15:40   ` Jan Engelhardt
2020-07-23 16:40   ` Eric Dumazet
2020-07-23 16:44     ` Christoph Hellwig
2020-07-23  6:08 ` [PATCH 05/26] net: switch copy_bpf_fprog_from_user to sockptr_t Christoph Hellwig
2020-07-23  6:08 ` [PATCH 06/26] net: switch sock_setbindtodevice " Christoph Hellwig
2020-07-23  6:08 ` [PATCH 07/26] net: switch sock_set_timeout " Christoph Hellwig
2020-07-23  6:08 ` [PATCH 08/26] " Christoph Hellwig
2020-07-23  8:39   ` [MPTCP] " Matthieu Baerts
2020-07-23  6:08 ` [PATCH 09/26] net/xfrm: switch xfrm_user_policy " Christoph Hellwig
2020-07-23  6:08 ` [PATCH 10/26] netfilter: remove the unused user argument to do_update_counters Christoph Hellwig
2020-07-23  6:08 ` [PATCH 11/26] netfilter: switch xt_copy_counters to sockptr_t Christoph Hellwig
2020-07-23  6:08 ` [PATCH 12/26] netfilter: switch nf_setsockopt " Christoph Hellwig
2020-07-27 15:03   ` Jason A. Donenfeld
2020-07-27 15:06     ` Christoph Hellwig
2020-07-27 16:16       ` Jason A. Donenfeld
2020-07-27 16:23         ` Christoph Hellwig
2020-07-28  8:07           ` David Laight
2020-07-28  8:17             ` Jason A. Donenfeld
2020-07-27 16:16     ` Christoph Hellwig
2020-07-27 16:21       ` Jason A. Donenfeld
2020-07-23  6:08 ` [PATCH 13/26] bpfilter: switch bpfilter_ip_set_sockopt " Christoph Hellwig
2020-07-23 11:16   ` David Laight
2020-07-23 11:44     ` 'Christoph Hellwig'
2020-07-23  6:08 ` [PATCH 14/26] net/ipv4: switch ip_mroute_setsockopt " Christoph Hellwig
2020-07-23  6:08 ` [PATCH 15/26] net/ipv4: merge ip_options_get and ip_options_get_from_user Christoph Hellwig
2020-07-23  6:08 ` [PATCH 16/26] net/ipv4: switch do_ip_setsockopt to sockptr_t Christoph Hellwig
2020-07-23  6:08 ` [PATCH 17/26] net/ipv6: switch ip6_mroute_setsockopt " Christoph Hellwig
2020-07-23  6:09 ` [PATCH 18/26] net/ipv6: split up ipv6_flowlabel_opt Christoph Hellwig
2020-07-23  6:09 ` [PATCH 19/26] net/ipv6: switch ipv6_flowlabel_opt to sockptr_t Christoph Hellwig
2020-07-27 12:15   ` Ido Schimmel
2020-07-27 13:00     ` Christoph Hellwig
2020-07-27 13:33       ` Ido Schimmel
2020-07-27 16:15         ` Christoph Hellwig
2020-07-27 18:22           ` Ido Schimmel
2020-07-27 13:24     ` David Laight
2020-07-23  6:09 ` [PATCH 20/26] net/ipv6: factor out a ipv6_set_opt_hdr helper Christoph Hellwig
2020-07-23  6:09 ` [PATCH 21/26] net/ipv6: switch do_ipv6_setsockopt to sockptr_t Christoph Hellwig
2020-07-23  6:09 ` [PATCH 22/26] net/udp: switch udp_lib_setsockopt " Christoph Hellwig
2020-07-23  6:09 ` [PATCH 23/26] net/tcp: switch ->md5_parse " Christoph Hellwig
2020-07-23  6:09 ` [PATCH 24/26] net/tcp: switch do_tcp_setsockopt " Christoph Hellwig
2020-07-23  6:09 ` [PATCH 25/26] net: pass a sockptr_t into ->setsockopt Christoph Hellwig
2020-07-23  8:39   ` [MPTCP] " Matthieu Baerts
2020-08-06 22:21   ` Eric Dumazet
2020-08-07  7:21     ` Christoph Hellwig
2020-08-07  9:18     ` David Laight
2020-08-07 18:29       ` Eric Dumazet
2020-08-08 13:54         ` David Laight
2020-07-23  6:09 ` [PATCH 26/26] net: optimize the sockptr_t for unified kernel/user address spaces Christoph Hellwig
2020-07-24 22:43 ` get rid of the address_space override in setsockopt v2 David Miller
2020-07-26  7:03   ` Christoph Hellwig
2020-07-26  7:08     ` Andreas Schwab
2020-07-26  7:46     ` David Miller
2020-07-27  9:51   ` David Laight [this message]
2020-07-27 13:48     ` Al Viro
2020-07-27 14:09       ` David Laight

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=8ae792c27f144d4bb5cbea0c1cce4eed@AcuMS.aculab.com \
    --to=david.laight@aculab.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=bridge@lists.linux-foundation.org \
    --cc=coreteam@netfilter.org \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=dccp@vger.kernel.org \
    --cc=edumazet@google.com \
    --cc=hch@lst.de \
    --cc=kuba@kernel.org \
    --cc=kuznet@ms2.inr.ac.ru \
    --cc=linux-afs@lists.infradead.org \
    --cc=linux-bluetooth@vger.kernel.org \
    --cc=linux-can@vger.kernel.org \
    --cc=linux-crypto@vger.kernel.org \
    --cc=linux-decnet-user@lists.sourceforge.net \
    --cc=linux-hams@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=linux-sctp@vger.kernel.org \
    --cc=linux-wpan@vger.kernel.org \
    --cc=linux-x25@vger.kernel.org \
    --cc=lvs-devel@vger.kernel.org \
    --cc=mptcp@lists.01.org \
    --cc=netdev@vger.kernel.org \
    --cc=netfilter-devel@vger.kernel.org \
    --cc=rds-devel@oss.oracle.com \
    --cc=tipc-discussion@lists.sourceforge.net \
    --cc=yoshfuji@linux-ipv6.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Bluetooth Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-bluetooth/0 linux-bluetooth/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-bluetooth linux-bluetooth/ https://lore.kernel.org/linux-bluetooth \
		linux-bluetooth@vger.kernel.org
	public-inbox-index linux-bluetooth

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-bluetooth


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git