Messages in this thread | | | From | Paul Moore <> | Date | Tue, 20 Oct 2020 19:10:53 -0400 | Subject | Re: [PATCH v17 0/4] overlayfs override_creds=off & nested get xattr fix |
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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
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