selinux.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Daniel Walsh <dwalsh@redhat.com>
To: Miloslav Trmac <mitr@redhat.com>, selinux@vger.kernel.org
Subject: New Container vulnerability could potentially use an SELinux fix.
Date: Fri, 7 Jun 2019 11:42:50 -0400	[thread overview]
Message-ID: <7ca438c7-4a41-4daa-fc3f-a46a2e0af945@redhat.com> (raw)

We have periodic vulnerablities around bad container images having
symbolic link attacks against the host.

One came out last week about doing a `podman cp`

Which would copy content from the host into the container.  The issue
was that if the container was running, it could trick the processes
copying content into it to follow a symbolic link to external of the
container image.

The question came up, is there a way to use SELinux to prevent this. And
sadly the answer right now is no, because we have no way to know what
the label of the process attempting to update the container file system
is running as.  Usually it will be running as unconfined_t.

One idea would be to add a rule to policy that control the following of
symbolic links to only those specified in policy.


Something like

SPECIALRESTRICTED TYPE container_file_t

allow container_file_t container_file_t:symlink follow;

Then if a process attempted to copy content onto a symbolic link from
container_file_t to a non container_file_t type, the kernel would deny
access.

Thoughts?





             reply	other threads:[~2019-06-07 15:58 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-07 15:42 Daniel Walsh [this message]
2019-06-07 16:44 ` New Container vulnerability could potentially use an SELinux fix Stephen Smalley
2019-06-07 21:06   ` Daniel Walsh
2019-06-07 21:26     ` Stephen Smalley
2019-06-08 14:08       ` Daniel Walsh
2019-06-10 14:08         ` Stephen Smalley
2019-06-10 14:37           ` Daniel Walsh
2019-06-10 15:00             ` Stephen Smalley
2019-06-10 16:58               ` Daniel Walsh
2019-06-10 17:01               ` Daniel Walsh

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=7ca438c7-4a41-4daa-fc3f-a46a2e0af945@redhat.com \
    --to=dwalsh@redhat.com \
    --cc=mitr@redhat.com \
    --cc=selinux@vger.kernel.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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).