linux/security/selinux
Jonathan Lebon 3e3e24b420 selinux: allow labeling before policy is loaded
Currently, the SELinux LSM prevents one from setting the
`security.selinux` xattr on an inode without a policy first being
loaded. However, this restriction is problematic: it makes it impossible
to have newly created files with the correct label before actually
loading the policy.

This is relevant in distributions like Fedora, where the policy is
loaded by systemd shortly after pivoting out of the initrd. In such
instances, all files created prior to pivoting will be unlabeled. One
then has to relabel them after pivoting, an operation which inherently
races with other processes trying to access those same files.

Going further, there are use cases for creating the entire root
filesystem on first boot from the initrd (e.g. Container Linux supports
this today[1], and we'd like to support it in Fedora CoreOS as well[2]).
One can imagine doing this in two ways: at the block device level (e.g.
laying down a disk image), or at the filesystem level. In the former,
labeling can simply be part of the image. But even in the latter
scenario, one still really wants to be able to set the right labels when
populating the new filesystem.

This patch enables this by changing behaviour in the following two ways:
1. allow `setxattr` if we're not initialized
2. don't try to set the in-core inode SID if we're not initialized;
   instead leave it as `LABEL_INVALID` so that revalidation may be
   attempted at a later time

Note the first hunk of this patch is mostly the same as a previously
discussed one[3], though it was part of a larger series which wasn't
accepted.

[1] https://coreos.com/os/docs/latest/root-filesystem-placement.html
[2] https://github.com/coreos/fedora-coreos-tracker/issues/94
[3] https://www.spinics.net/lists/linux-initramfs/msg04593.html

Co-developed-by: Victor Kamensky <kamensky@cisco.com>
Signed-off-by: Victor Kamensky <kamensky@cisco.com>
Signed-off-by: Jonathan Lebon <jlebon@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-10-01 09:45:35 -04:00
..
include selinux/stable-5.4 PR 20190917 2019-09-23 11:21:04 -07:00
ss selinux/stable-5.4 PR 20190917 2019-09-23 11:21:04 -07:00
.gitignore SELinux: add .gitignore files for dynamic classes 2009-10-24 09:42:27 +08:00
avc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
hooks.c selinux: allow labeling before policy is loaded 2019-10-01 09:45:35 -04:00
ibpkey.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295 2019-06-05 17:36:38 +02:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile SELinux: Remove unused selinux_is_enabled 2019-01-08 13:18:44 -08:00
netif.c selinux/stable-5.4 PR 20190917 2019-09-23 11:21:04 -07:00
netlabel.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 2019-05-21 11:28:45 +02:00
netlink.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
netnode.c selinux/stable-5.4 PR 20190917 2019-09-23 11:21:04 -07:00
netport.c selinux/stable-5.4 PR 20190917 2019-09-23 11:21:04 -07:00
nlmsgtab.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-22 08:59:24 -04:00
selinuxfs.c selinux: remove load size limit 2019-10-01 09:29:04 -04:00
xfrm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00