Remove logic to fake /system in overlayfs
It is better to guarantee that a /system or / entry will be present in
first stage mount than it is to maintain the code to fake an entry if
its not present in the input fstab.
Test: adb-remount-test.sh on blueline
Change-Id: I8aa3e704903b8abf06b1c63be071913a9de58eb3
diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
index b508b56..df1e326 100644
--- a/fs_mgr/fs_mgr_overlayfs.cpp
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -565,26 +565,6 @@
if (!duplicate_or_more_specific) mounts.emplace_back(new_mount_point);
}
- // if not itemized /system or /, system as root, fake one up?
-
- // do we want or need to?
- if (mount_point && ("/system"s != mount_point)) return mounts;
- if (std::find(mounts.begin(), mounts.end(), "/system") != mounts.end()) return mounts;
-
- // fs_mgr_overlayfs_verity_enabled_list says not to?
- if (std::find(verity.begin(), verity.end(), "system") != verity.end()) return mounts;
-
- // confirm that fstab is missing system
- if (GetEntryForMountPoint(fstab, "/") != nullptr ||
- GetEntryForMountPoint(fstab, "/system") != nullptr) {
- return mounts;
- }
-
- // We have a stunted fstab (w/o system or / ) passed in by the caller,
- // verity claims are assumed accurate because they are collected internally
- // from fs_mgr_fstab_default() from within fs_mgr_update_verity_state(),
- // Can (re)evaluate /system with impunity since we know it is ever-present.
- mounts.emplace_back("/system");
return mounts;
}
diff --git a/init/first_stage_mount.cpp b/init/first_stage_mount.cpp
index 7d5bf57..1b077bc 100644
--- a/init/first_stage_mount.cpp
+++ b/init/first_stage_mount.cpp
@@ -157,6 +157,37 @@
return fstab;
}
+static bool GetRootEntry(FstabEntry* root_entry) {
+ Fstab proc_mounts;
+ if (!ReadFstabFromFile("/proc/mounts", &proc_mounts)) {
+ LOG(ERROR) << "Could not read /proc/mounts and /system not in fstab, /system will not be "
+ "available for overlayfs";
+ return false;
+ }
+
+ auto entry = std::find_if(proc_mounts.begin(), proc_mounts.end(), [](const auto& entry) {
+ return entry.mount_point == "/" && entry.fs_type != "rootfs";
+ });
+
+ if (entry == proc_mounts.end()) {
+ LOG(ERROR) << "Could not get mount point for '/' in /proc/mounts, /system will not be "
+ "available for overlayfs";
+ return false;
+ }
+
+ *root_entry = std::move(*entry);
+
+ // We don't know if we're avb or not, so we query device mapper as if we are avb. If we get a
+ // success, then mark as avb, otherwise default to verify.
+ auto& dm = android::dm::DeviceMapper::Instance();
+ if (dm.GetState("vroot") != android::dm::DmDeviceState::INVALID) {
+ root_entry->fs_mgr_flags.avb = true;
+ } else {
+ root_entry->fs_mgr_flags.verify = true;
+ }
+ return true;
+}
+
// Class Definitions
// -----------------
FirstStageMount::FirstStageMount(Fstab fstab)
@@ -443,7 +474,7 @@
if (system_partition == fstab_.end()) return true;
- if (MountPartition(system_partition, true /* erase_used_fstab_entry */)) {
+ if (MountPartition(system_partition, false)) {
SwitchRoot("/system");
} else {
PLOG(ERROR) << "Failed to mount /system";
@@ -487,6 +518,12 @@
if (!TrySkipMountingPartitions()) return false;
for (auto current = fstab_.begin(); current != fstab_.end();) {
+ // We've already mounted /system above.
+ if (current->mount_point == "/system") {
+ ++current;
+ continue;
+ }
+
Fstab::iterator end;
if (!MountPartition(current, false, &end)) {
if (current->fs_mgr_flags.no_fail) {
@@ -503,6 +540,15 @@
current = end;
}
+ // If we don't see /system or / in the fstab, then we need to create an root entry for
+ // overlayfs.
+ if (!GetEntryForMountPoint(&fstab_, "/system") && !GetEntryForMountPoint(&fstab_, "/")) {
+ FstabEntry root_entry;
+ if (GetRootEntry(&root_entry)) {
+ fstab_.emplace_back(std::move(root_entry));
+ }
+ }
+
// heads up for instantiating required device(s) for overlayfs logic
const auto devices = fs_mgr_overlayfs_required_devices(&fstab_);
for (auto const& device : devices) {