CHROMIUM: fuse: virtiofs: Run security hooks on new inodes

Temporary fix to allow user builds to work. Remove after
https://chromium-review.googlesource.com/c/crosvm/crosvm/+/4979355

 is
merged.

This replaces the FROMLIST patches that were providing the same
behavior.  Since those patches are basically being ignored by the
maintainer and they change the protocol, we can't really maintain them
long term. Upstream has already landed another change that uses the same
feature bit for a different feature.

This patch implements the same behavior without changing the public
interface by using security_inode_init_security instead of
security_dentry_init_security.  One downside of this change is that
security xattrs are not applied atomically on creation on the host.
However they are still atomic from the perspective of the guest. This
isn't a big issue for arcvm because it always runs restorecon on boot
anyway so even in the case of power loss, the xattrs will be set
appropriately the next time arcvm boots.

This behavior is always enabled for virtiofs and always disabled for
regular fuse filesystems, again so that we don't need to make changes to
the public protocol.

BUG=b:304606864
TEST=arc.Boot.vm works with user builds

[5.4-arcvm: picked from 5.4]
Signed-off-by: Chirantan Ekbote <chirantan@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2581172
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2604783


Commit-Queue: Lepton Wu <lepton@chromium.org>
Reviewed-by: Lepton Wu <lepton@chromium.org>

[5.10-arcvm: context conflict resolved]
Change-Id: I82d857e13fbd68a69eda80a70d2d38c08beb1921
Signed-off-by: Hikaru Nishida <hikalium@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2992595


Reviewed-by: Suleiman Souhlal <suleiman@chromium.org>

[arcvm-5.15-gki-base: context conflict resolved]
Change-Id: Ice3990240dacb256cff2a96d343a0b14d0237028
Signed-off-by: Richard Fung <richardfung@google.com>