From: Paul Moore <paul@paul-moore.com>
To: Mark Salyzyn <salyzyn@android.com>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
Miklos Szeredi <miklos@szeredi.hu>,
Jonathan Corbet <corbet@lwn.net>, Vivek Goyal <vgoyal@redhat.com>,
"Eric W . Biederman" <ebiederm@xmission.com>,
Amir Goldstein <amir73il@gmail.com>,
Randy Dunlap <rdunlap@infradead.org>,
Stephen Smalley <sds@tycho.nsa.gov>,
John Stultz <john.stultz@linaro.org>,
linux-doc@vger.kernel.org, linux-security-module@vger.kernel.org,
selinux@vger.kernel.org
Subject: Re: [PATCH v17 0/4] overlayfs override_creds=off & nested get xattr fix
Date: Tue, 20 Oct 2020 19:10:53 -0400 [thread overview]
Message-ID: <CAHC9VhRMj-y2RsJ6HnbVYJV9j_snEqnmoNc6-wFacLG9wyqJpQ@mail.gmail.com> (raw)
In-Reply-To: <20201020191732.4049987-1-salyzyn@android.com>
On Tue, Oct 20, 2020 at 3:17 PM Mark Salyzyn <salyzyn@android.com> wrote:
>
> Mark Salyzyn (3):
> Add flags option to get xattr method paired to __vfs_getxattr
> overlayfs: handle XATTR_NOSECURITY flag for get xattr method
> overlayfs: override_creds=off option bypass creator_cred
>
> Mark Salyzyn + John Stultz (1):
> overlayfs: inode_owner_or_capable called during execv
>
> The first three patches address fundamental security issues that should
> be solved regardless of the override_creds=off feature.
>
> The fourth adds the feature depends on these other fixes.
>
> By default, all access to the upper, lower and work directories is the
> recorded mounter's MAC and DAC credentials. The incoming accesses are
> checked against the caller's credentials.
>
> If the principles of least privilege are applied for sepolicy, the
> mounter's credentials might not overlap the credentials of the caller's
> when accessing the overlayfs filesystem. For example, a file that a
> lower DAC privileged caller can execute, is MAC denied to the
> generally higher DAC privileged mounter, to prevent an attack vector.
>
> We add the option to turn off override_creds in the mount options; all
> subsequent operations after mount on the filesystem will be only the
> caller's credentials. The module boolean parameter and mount option
> override_creds is also added as a presence check for this "feature",
> existence of /sys/module/overlay/parameters/overlay_creds
>
> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> Cc: Miklos Szeredi <miklos@szeredi.hu>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Vivek Goyal <vgoyal@redhat.com>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> Cc: Amir Goldstein <amir73il@gmail.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Stephen Smalley <sds@tycho.nsa.gov>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: linux-doc@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> To: linux-fsdevel@vger.kernel.org
> To: linux-unionfs@vger.kernel.org
> Cc: linux-security-module@vger.kernel.org
> Cc: kernel-team@android.com
The SELinux list should also be CC'd on these patches. For those who
may just be seeing this, the lore link is below:
https://lore.kernel.org/linux-security-module/20201020191732.4049987-1-salyzyn@android.com/T/#t
--
paul moore
www.paul-moore.com
prev parent reply other threads:[~2020-10-20 23:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 19:17 [PATCH v17 0/4] overlayfs override_creds=off & nested get xattr fix Mark Salyzyn
2020-10-20 19:17 ` [PATCH v17 1/4] Add flags option to get xattr method paired to __vfs_getxattr Mark Salyzyn
2020-10-21 1:17 ` Paul Moore
2020-10-21 12:07 ` Mark Salyzyn
2020-10-23 0:46 ` Paul Moore
2020-10-20 19:17 ` [PATCH v17 2/4] overlayfs: handle XATTR_NOSECURITY flag for get xattr method Mark Salyzyn
2020-10-20 22:38 ` kernel test robot
2020-10-21 12:12 ` Mark Salyzyn
2020-10-20 19:17 ` [PATCH v17 3/4] overlayfs: override_creds=off option bypass creator_cred Mark Salyzyn
2020-10-20 19:17 ` [PATCH v17 4/4] overlayfs: inode_owner_or_capable called during execv Mark Salyzyn
2020-10-20 23:10 ` Paul Moore [this message]
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