init.rc: Remount / with MS_REMOUNT|MS_BIND
Since we only want to change the ro flag on / (and leave all other mount
flags alone), this can also be achieved by passing MS_REMOUNT|MS_BIND,
even if the mount is not a bind-mount.
This aims to make running Android within a user namespace easier, since
remounts without the MS_BIND flag are forbidden.
Bug: 73255020
Test: aosp_sailfish still boots
Test: rootfs on / type rootfs (rw,seclabel)
/dev/root on / type ext4 (ro,seclabel,relatime,data=ordered)
Change-Id: I2f89a8badfc467db47304c9355648e8fd8ad1272
diff --git a/rootdir/init.rc b/rootdir/init.rc
index f008c17..da3f824 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -318,8 +318,9 @@
start hwservicemanager
start vndservicemanager
- # once everything is setup, no need to modify /
- mount rootfs rootfs / ro remount
+ # Once everything is setup, no need to modify /.
+ # The bind+ro combination avoids modifying any other mount flags.
+ mount rootfs rootfs / remount bind ro
# Mount shared so changes propagate into child namespaces
mount rootfs rootfs / shared rec
# Mount default storage into root namespace