Add a limit to how many VMs one app can own
Running `atest MicrodroidTests` creates ~260 VMs, so choose a bigger
limit.
Bug: 294177871
Test: virtualizationservice_test
Change-Id: Idb1b7a54d1ff8fb79f7024d325221b3912560b0a
diff --git a/virtualizationservice/src/maintenance.rs b/virtualizationservice/src/maintenance.rs
index f950db9..8efc58d 100644
--- a/virtualizationservice/src/maintenance.rs
+++ b/virtualizationservice/src/maintenance.rs
@@ -40,6 +40,9 @@
/// parcel fits within max AIDL message size.
const DELETE_MAX_BATCH_SIZE: usize = 100;
+/// Maximum number of VM IDs that a single app can have.
+const MAX_VM_IDS_PER_APP: usize = 400;
+
/// State related to VM secrets.
pub struct State {
sk: binder::Strong<dyn ISecretkeeper>,
@@ -101,6 +104,24 @@
pub fn add_id(&mut self, vm_id: &VmId, user_id: u32, app_id: u32) -> Result<()> {
let user_id: i32 = user_id.try_into().context(format!("user_id {user_id} out of range"))?;
let app_id: i32 = app_id.try_into().context(format!("app_id {app_id} out of range"))?;
+
+ // To prevent unbounded growth of VM IDs (and the associated state) for an app, limit the
+ // number of VM IDs per app.
+ let count = self
+ .vm_id_db
+ .count_vm_ids_for_app(user_id, app_id)
+ .context("failed to determine VM count")?;
+ if count >= MAX_VM_IDS_PER_APP {
+ // The owner has too many VM IDs, so delete the oldest IDs so that the new VM ID
+ // creation can progress/succeed.
+ let purge = 1 + count - MAX_VM_IDS_PER_APP;
+ let old_vm_ids = self
+ .vm_id_db
+ .oldest_vm_ids_for_app(user_id, app_id, purge)
+ .context("failed to find oldest VM IDs")?;
+ error!("Deleting {purge} of {count} VM IDs for user_id={user_id}, app_id={app_id}");
+ self.delete_ids(&old_vm_ids);
+ }
self.vm_id_db.add_vm_id(vm_id, user_id, app_id)
}
@@ -396,6 +417,39 @@
assert_eq!(vec![VM_ID5], sk_state.vm_id_db.vm_ids_for_user(USER3).unwrap());
}
+ #[test]
+ fn test_sk_state_too_many_vms() {
+ let history = Arc::new(Mutex::new(Vec::new()));
+ let mut sk_state = new_test_state(history.clone(), 20);
+
+ // Every VM ID added up to the limit is kept.
+ for idx in 0..MAX_VM_IDS_PER_APP {
+ let mut vm_id = [0u8; 64];
+ vm_id[0..8].copy_from_slice(&(idx as u64).to_be_bytes());
+ sk_state.add_id(&vm_id, USER1 as u32, APP_A as u32).unwrap();
+ assert_eq!(idx + 1, sk_state.vm_id_db.count_vm_ids_for_app(USER1, APP_A).unwrap());
+ }
+ assert_eq!(
+ MAX_VM_IDS_PER_APP,
+ sk_state.vm_id_db.count_vm_ids_for_app(USER1, APP_A).unwrap()
+ );
+
+ // Beyond the limit it's one in, one out.
+ for idx in MAX_VM_IDS_PER_APP..MAX_VM_IDS_PER_APP + 10 {
+ let mut vm_id = [0u8; 64];
+ vm_id[0..8].copy_from_slice(&(idx as u64).to_be_bytes());
+ sk_state.add_id(&vm_id, USER1 as u32, APP_A as u32).unwrap();
+ assert_eq!(
+ MAX_VM_IDS_PER_APP,
+ sk_state.vm_id_db.count_vm_ids_for_app(USER1, APP_A).unwrap()
+ );
+ }
+ assert_eq!(
+ MAX_VM_IDS_PER_APP,
+ sk_state.vm_id_db.count_vm_ids_for_app(USER1, APP_A).unwrap()
+ );
+ }
+
struct Irreconcilable;
impl IVirtualizationReconciliationCallback for Irreconcilable {
diff --git a/virtualizationservice/src/maintenance/vmdb.rs b/virtualizationservice/src/maintenance/vmdb.rs
index 47704bc..273f340 100644
--- a/virtualizationservice/src/maintenance/vmdb.rs
+++ b/virtualizationservice/src/maintenance/vmdb.rs
@@ -272,6 +272,34 @@
Ok(vm_ids)
}
+ /// Determine the number of VM IDs associated with `(user_id, app_id)`.
+ pub fn count_vm_ids_for_app(&mut self, user_id: i32, app_id: i32) -> Result<usize> {
+ let mut stmt = self
+ .conn
+ .prepare("SELECT COUNT(vm_id) FROM main.vmids WHERE user_id = ? AND app_id = ?;")
+ .context("failed to prepare SELECT stmt")?;
+ stmt.query_row(params![user_id, app_id], |row| row.get(0)).context("query failed")
+ }
+
+ /// Return the `count` oldest VM IDs associated with `(user_id, app_id)`.
+ pub fn oldest_vm_ids_for_app(
+ &mut self,
+ user_id: i32,
+ app_id: i32,
+ count: usize,
+ ) -> Result<Vec<VmId>> {
+ // SQLite considers NULL columns to be smaller than values, so rows left over from a v0
+ // database will be listed first.
+ let mut stmt = self
+ .conn
+ .prepare(
+ "SELECT vm_id FROM main.vmids WHERE user_id = ? AND app_id = ? ORDER BY created LIMIT ?;",
+ )
+ .context("failed to prepare SELECT stmt")?;
+ let rows = stmt.query(params![user_id, app_id, count]).context("query failed")?;
+ Self::vm_ids_from_rows(rows)
+ }
+
/// Return all of the `(user_id, app_id)` pairs present in the database.
pub fn get_all_owners(&mut self) -> Result<Vec<(i32, i32)>> {
let mut stmt = self
@@ -344,6 +372,19 @@
fn show_contents(db: &VmIdDb) {
let mut stmt = db.conn.prepare("SELECT * FROM main.vmids;").unwrap();
let mut rows = stmt.query(()).unwrap();
+ println!("DB contents:");
+ while let Some(row) = rows.next().unwrap() {
+ println!(" {row:?}");
+ }
+ }
+
+ fn show_contents_for_app(db: &VmIdDb, user_id: i32, app_id: i32, count: usize) {
+ let mut stmt = db
+ .conn
+ .prepare("SELECT vm_id, created FROM main.vmids WHERE user_id = ? AND app_id = ? ORDER BY created LIMIT ?;")
+ .unwrap();
+ let mut rows = stmt.query(params![user_id, app_id, count]).unwrap();
+ println!("First (by created) {count} rows for app_id={app_id}");
while let Some(row) = rows.next().unwrap() {
println!(" {row:?}");
}
@@ -457,31 +498,39 @@
assert_eq!(vec![VM_ID1, VM_ID2, VM_ID3], db.vm_ids_for_user(USER1).unwrap());
assert_eq!(vec![VM_ID1, VM_ID2, VM_ID3], db.vm_ids_for_app(USER1, APP_A).unwrap());
+ assert_eq!(3, db.count_vm_ids_for_app(USER1, APP_A).unwrap());
assert_eq!(vec![VM_ID4], db.vm_ids_for_app(USER2, APP_B).unwrap());
+ assert_eq!(1, db.count_vm_ids_for_app(USER2, APP_B).unwrap());
assert_eq!(vec![VM_ID5], db.vm_ids_for_user(USER3).unwrap());
assert_eq!(empty, db.vm_ids_for_user(USER_UNKNOWN).unwrap());
assert_eq!(empty, db.vm_ids_for_app(USER1, APP_UNKNOWN).unwrap());
+ assert_eq!(0, db.count_vm_ids_for_app(USER1, APP_UNKNOWN).unwrap());
db.delete_vm_ids(&[VM_ID2, VM_ID3]).unwrap();
assert_eq!(vec![VM_ID1], db.vm_ids_for_user(USER1).unwrap());
assert_eq!(vec![VM_ID1], db.vm_ids_for_app(USER1, APP_A).unwrap());
+ assert_eq!(1, db.count_vm_ids_for_app(USER1, APP_A).unwrap());
// OK to delete things that don't exist.
db.delete_vm_ids(&[VM_ID2, VM_ID3]).unwrap();
assert_eq!(vec![VM_ID1], db.vm_ids_for_user(USER1).unwrap());
assert_eq!(vec![VM_ID1], db.vm_ids_for_app(USER1, APP_A).unwrap());
+ assert_eq!(1, db.count_vm_ids_for_app(USER1, APP_A).unwrap());
db.add_vm_id(&VM_ID2, USER1, APP_A).unwrap();
db.add_vm_id(&VM_ID3, USER1, APP_A).unwrap();
assert_eq!(vec![VM_ID1, VM_ID2, VM_ID3], db.vm_ids_for_user(USER1).unwrap());
assert_eq!(vec![VM_ID1, VM_ID2, VM_ID3], db.vm_ids_for_app(USER1, APP_A).unwrap());
+ assert_eq!(3, db.count_vm_ids_for_app(USER1, APP_A).unwrap());
assert_eq!(vec![VM_ID4], db.vm_ids_for_app(USER2, APP_B).unwrap());
+ assert_eq!(1, db.count_vm_ids_for_app(USER2, APP_B).unwrap());
assert_eq!(vec![VM_ID5], db.vm_ids_for_user(USER3).unwrap());
assert_eq!(empty, db.vm_ids_for_user(USER_UNKNOWN).unwrap());
assert_eq!(empty, db.vm_ids_for_app(USER1, APP_UNKNOWN).unwrap());
+ assert_eq!(0, db.count_vm_ids_for_app(USER1, APP_UNKNOWN).unwrap());
assert_eq!(
vec![(USER1, APP_A), (USER2, APP_B), (USER3, APP_C)],
@@ -513,4 +562,47 @@
assert_eq!(vec![VM_ID1, VM_ID2, VM_ID3], db.vm_ids_for_user(USER1).unwrap());
show_contents(&db);
}
+
+ #[test]
+ fn test_remove_oldest_with_upgrade() {
+ let mut db = new_test_db_version(0);
+ let version = db.schema_version().unwrap();
+ assert_eq!(0, version);
+
+ let remove_count = 10;
+ let mut want = vec![];
+
+ // Manually insert rows before upgrade.
+ const V0_COUNT: usize = 5;
+ for idx in 0..V0_COUNT {
+ let mut vm_id = [0u8; 64];
+ vm_id[0..8].copy_from_slice(&(idx as u64).to_be_bytes());
+ if want.len() < remove_count {
+ want.push(vm_id);
+ }
+ db.conn
+ .execute(
+ "REPLACE INTO main.vmids (vm_id, user_id, app_id) VALUES (?1, ?2, ?3);",
+ params![&vm_id, &USER1, APP_A],
+ )
+ .unwrap();
+ }
+
+ // Now move to v1.
+ db.upgrade_tables_v0_v1().unwrap();
+ let version = db.schema_version().unwrap();
+ assert_eq!(1, version);
+
+ for idx in V0_COUNT..40 {
+ let mut vm_id = [0u8; 64];
+ vm_id[0..8].copy_from_slice(&(idx as u64).to_be_bytes());
+ if want.len() < remove_count {
+ want.push(vm_id);
+ }
+ db.add_vm_id(&vm_id, USER1, APP_A).unwrap();
+ }
+ show_contents_for_app(&db, USER1, APP_A, 10);
+ let got = db.oldest_vm_ids_for_app(USER1, APP_A, 10).unwrap();
+ assert_eq!(got, want);
+ }
}