oss-security - Re: CVE Request: Linux: IB/security: Restrict use of the write() interface'

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1462823339.4268.54.camel@opteya.com>
Date: Mon, 09 May 2016 21:48:59 +0200
From: Yann Droneaud <ydroneaud@...eya.com>
To: oss-security@...ts.openwall.com
Cc: Doug Ledford <dledford@...hat.com>, Red Hat Security Response Team
	 <secalert@...hat.com>, Ben Hutchings <benh@...ian.org>, 
	linux-rdma@...r.kernel.org
Subject: Re: CVE Request: Linux: IB/security: Restrict use of
 the write() interface'

Hi,

Le samedi 07 mai 2016 à 06:22 +0200, Salvatore Bonaccorso a écrit :
> 
> Jann Horn reported an issue in the infiniband stack. It has been
> fixed
> in v4.6-rc6 with commit e6bd18f57aad1a2d1ef40e646d03ed0f2515c9e3:
> 
> https://git.kernel.org/linus/e6bd18f57aad1a2d1ef40e646d03ed0f2515c9e3
> 
> > 
> > IB/security: Restrict use of the write() interface
> > The drivers/infiniband stack uses write() as a replacement for
> > bi-directional ioctl().  This is not safe. There are ways to
> > trigger write calls that result in the return structure that
> > is normally written to user space being shunted off to user
> > specified kernel memory instead.
> > 
> > For the immediate repair, detect and deny suspicious accesses to
> > the write API.
> > 
> > For long term, update the user space libraries and the kernel API
> > to something that doesn't present the same security vulnerabilities
> > (likely a structured ioctl() interface).
> > 
> > The impacted uAPI interfaces are generally only available if
> > hardware from drivers/infiniband is installed in the system.

As a workaround, I would suggest that systems which do not require
(userspace) RDMA/Infiniband to blacklist/remove the following modules:

  rdma_ucm
  ib_uverbs
  ib_ucm
  ib_umad

For example, adds the following in /etc/modprobe.d/blacklist.conf

  blacklist rdma_ucm
  blacklist ib_uverbs
  blacklist ib_ucm
  blacklist ib_umad

Those building their own kernel might want to disable, if not already,

  CONFIG_INFINIBAND_USER_ACCESS, 
  CONFIG_INFINIBAND_USER_MAD,
  CONFIG_INFINIBAND_ADDR_TRANS

(Unfortunately the last one will also disable those features:
  iSCSI Extensions for RDMA (iSER)
  iSCSI Extensions for RDMA (iSER) target support
  RDS over Infiniband and iWARP
  9P RDMA Transport (Experimental)
  RPC-over-RDMA transport
    (which actually disable NFSoRDMA))

Regards.

-- 
Yann Droneaud
OPTEYA

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.